Report on Fukushima Daiichi NPP precursor events

International Nuclear Information System (INIS)

2014-01-01

The main questions to be answered by this report were: The Fukushima Daiichi NPP accident, could it have been prevented? If there is a next severe accident, may it be prevented? To answer the first question, the report addressed several aspects. First, the report investigated whether precursors to the Fukushima Daiichi NPP accident existed in the operating experience; second, the reasons why these precursors did not evolve into a severe accident. Third, whether lessons learned from these precursor events were adequately considered by member countries; and finally, if the operating experience feedback system needs to be improved, based on the previous analysis. To address the second question which is much more challenging, the report considered precursor events identified through a search and analysis of the IRS database and also precursors events based on risk significance. Both methods can point out areas where further work may be needed, even if it depends heavily on design and site-specific factors. From the operating experience side, more efforts are needed to ensure timely and full implementation of lessons learnt from precursor events. Concerning risk considerations, a combined use of risk precursors and operating experience may drive to effective changes to plants to reduce risk. The report also contains a short description and evaluation of selected precursors that are related to the course of the Fukushima Daiichi NPP accident. The report addresses the question whether operating experience feedback can be effectively used to identify plant vulnerabilities and minimize potential for severe core damage accidents. Based on several of the precursor events national or international in-depth evaluations were started. The vulnerability of NPPs due to external and internal flooding has clearly been addressed. In addition to the IRS based investigation, the WGRISK was asked to identify important precursor events based on risk significance. These precursors have

Unsolved issues related to thermal-hydraulics in the suppression chamber during Fukushima Daiichi accident progressions

International Nuclear Information System (INIS)

Mizokami, Shinya; Yamada, Daichi; Honda, Takeshi; Yamauchi, Daisuke; Yamanaka, Yasunori

2016-01-01

On 11 March 2011, the Great East Japan Earthquake and Tsunami hit the Fukushima Daiichi Nuclear Power Station. The Fukushima Daiichi Units 1-3 lost all DC and AC power supplies, which set in motion a chain of events that led to releases of radioactivity to the environment. Since then, TEPCO has made many efforts to investigate the accident progressions and the status of the reactors and containment vessels. However, there still exist several tens of unsolved issues to be investigated for the fully understanding of the accident. In this paper, we introduce the unsolved issues related to thermal-hydraulics in the suppression chamber during the Fukushima Daiichi accident progressions. Especially, in Units 2 and 3, there are possibilities that thermal stratification inside their suppression chambers played an important role. It is important that these phenomena are addressed following both theoretical and experimental approaches as support to severe accident simulations. (author)

Applicability of health physics lessons learned from the Three Mile Island Unit 2 accident to the Fukushima Daiichi accident.

Science.gov (United States)

Bevelacqua, J J

2012-02-01

The TMI-2 and Fukushima Daiichi accidents appear to be dissimilar because they involve different reactor types. However, the health physics related lessons learned from TMI-2 are applicable, and can enhance the Fukushima Daiichi recovery effort. Copyright © 2011 Elsevier Ltd. All rights reserved.

Decontamination and concrete core sampling by teleoperated robot at Fukushima Daiichi reactor buildings

International Nuclear Information System (INIS)

Watanabe, Masaru; Onitsuka, Hironori; Shimonabe, Noriaki; Fujita, Jun; Matsumura, Takumi; Okumura, Atsushi

2015-01-01

For decommissioning of Fukushima daiichi nuclear power station, reduction of the dose equivalent rates inside the reactor buildings is an important issue. Concrete core sampling from the buildings to investigate the contamination is necessary for study about effective decontamination. However, dose rate inside the reactor buildings is very high. For example, dose rate of 1st floor on the Unit 1 is 1.2 - 1820 [mSv / h], the Unit 2 is 2.5 - 220 [mSv / h] and Unit 3 is 2.2 - 4780 [mSv / h]. So it is difficult for workers to work long hours. Therefore, a teleoperated robot, named 'MHI-MEISTeR (Mitsubishi Heavy Industries - Maintenance Equipment Integrated System of Telecontrol Robot)', has been developed to conduct operations like concrete core samples from the reactor buildings. Actually, some concrete core samples from Fukushima daiichi were taken by MHI-MEISTeR. In addition, MHI-MEISTeR is designed as a versatile robot, and so it can conduct suction / blast decontamination works as well as concrete core sampling. The above operations were performed by MHI-MEISTeR in Fukushima daiichi nuclear power station. (author)

Activities for the remediation of TEPCO's Fukushima Daiichi nuclear power plant

Energy Technology Data Exchange (ETDEWEB)

Kinoshita, Hirofumi; Kometani, Yutaka; Asano, Takashi; Ishiwata, Masayuki; Fukasawa, Tetsuo [Hitachi-GE Nuclear Energy, Ltd., 2-2, Omika-cho, 5-chome, Hitachi-shi Ibaraki-ken, 319-1221 (Japan); Tadokoro, Takahiro; Nagumo, Yasushi; Kani, Yuko; Matsui, Tetsuya [Hitachi Research Laboratory, Hitachi, Ltd. 2-2, Omika-cho, 5-chome, Hitachi-shi Ibaraki-ken, 319-1221 (Japan)

2013-07-01

With the aim of fulfilling recovery work for the Fukushima Daiichi NPP, technological efforts have been made for the development of a survey robot system, adequate communication infrastructure technologies, high radiation environment compatible gamma cameras, heavy machinery-type robots (ASTACO-SoRa), remote decontamination devices (AROUNDER), and contaminated waste water treatment system. We have developed a new type of absorbents which remove cesium (Cs) and strontium (Sr) simultaneously at a high removal rate of 99 % or more. We will provide valuable solutions and rational systems for waste water treatment using this developed adsorbent as well as other various adsorbents for the recovery of Fukushima Daiichi NPP.

Technological Lessons from the Fukushima Dai-Ichi Accident

Science.gov (United States)

2016-06-01

a devastating earth - quake and tsunami. One of the many secondary effects of these disas- ters was a loss of control of the Fukushima Dai-Ichi nuclear...plant needed to be continually cooled, vast quantities of contaminated water was (and is) created, particularly at the plant. Certain radioisotopes ...terminated, although it could be revived at some future date . The political difficulties of developing a similar storage site in densely populated

Severe accident management: radiation dose control, Fukushima Daiichi and TMI-2 nuclear plant accidents

International Nuclear Information System (INIS)

Shaw, Roger

2014-01-01

This presentation presents valuable dose information related to the Fukushima Daiichi and Three Mile Island Unit 2 (TMI-2) Nuclear Plant accidents. Dose information is provided for what is well known for TMI-2, and what is available for Fukushima Daiichi. Particular emphasis is placed on the difference between the type of reactors involved, overarching plant damage issues, and radiation worker dose outcomes. For TMI-2, more in depth dose data is available for the accident and the subsequent recovery efforts. The comparisons demonstrate the need to understand the wide variation in potential dose management measures and outcomes for severe reactor accidents. (author)

The third update of the Fukushima Daiichi Nuclear Station accident. September 1 through November 30, 2011

International Nuclear Information System (INIS)

Shibutani, Yu

2011-01-01

This article provides the third update of the Fukushima Daiichi accident that occurred on March 11, 2011. In the report of the first update of the Fukushima Daiichi accident on March 11 through May 31, the situation was reported on both on-site and off-site of the Fukushima Daiichi, including; failed cooldown of decay heat and meltdown of stricken reactors; emergency evacuation of local residents, radioactive contamination, spread of biased rumors by the information closure by government, regional cooperation with China, Taiwan and Korea, and visit of IAEA investigation team to Japan. The report of the second update on June 1 through August 31 reported the issues of, harsh public criticism against government and electric power companies, results of the public opinion poll, a sort of gentlemen's agreements between nuclear power companies and local governments which would be peculiar tradition in Japan, the first revision of the road map to cold shutdown of stricken reactors, and submission of report on Fukushima Daiichi accident to International Atomic Energy Agency (IAEA). This article provides the third update from September 1 through November 30, particularly on the issues of the second revision of the road map where the “cold shutdown” state should be reached before the end of 2011, the overview of governmental organization on the overall energy and nuclear policy, and the establishment of the nuclear disaster response headquarters (HQ) in the Prime Minister's Office. The HQ in collaboration with Tokyo Electric Power Company (TEPCO) decided the framework of road map plans, provision of various assistance and compensation for the residents affected by the nuclear incident, redefinition by the Nuclear Safety Commission for evacuation areas, recovery process of radioactive decontaminated areas, investigation and verification of the Fukushima Daiichi accident, reorganization of TEPCO management and financial system, establishment of damage compensation scheme

The NEA benchmark study of the accident at the Fukushima Daiichi NPP

International Nuclear Information System (INIS)

Koganeya, Toshiyuki

2015-01-01

In November 2012, the NEA, under the aegis of the Committee on the Safety of Nuclear Installations (CSNI), initiated a joint research project called the Benchmark Study of the Accident at the Fukushima Daiichi Nuclear Power Station (BSAF). Objectives of this project include supporting Fukushima Daiichi decommissioning by analysing accident progression and the current status of the reactors, such as fuel debris distribution in the reactor pressure vessels and primary containment vessels in preparation for fuel debris removal. A second objective of the project is to improve SA (severe analysis) codes through comparisons with data from the Fukushima reactors. So as to enhance communication between analysts and those involved in decommissioning activities, participants in the project have been discussing the remaining uncertainties in relation to understanding the accident and the data needs from the viewpoint of the analysts. Since the accident sequences at the Fukushima Daiichi site include a wide range of phenomena, a phased approach is being applied in this benchmark exercise while awaiting more detailed information on debris examination and other factors. This article provides an overview of the project (scope, input data and boundary conditions, participants (from eight countries), analytical approach - common case and best estimate case) as well as an outline of the project's next phase (BASF phase 2) that begins in June 2015

Study on disaster waste around Fukushima Daiichi NPS

Energy Technology Data Exchange (ETDEWEB)

NONE

2012-08-15

Extreme difficulties exists in Fukushima Prefecture in disposing of waste generated from the tsunami disaster (hereinafter referred to as disaster waste) and contaminated with radioactive material released from the crippled Fukushima Daiichi Nuclear Power Station. Although the waste should be treated according to the level of radioactivity, there were only air dose rates and radionuclide analyses of soil due to monitoring around the Fukushima Daiichi Nuclear Power Station and there had been no information on the radioactivity concentration of the disaster waste. The radioactivity concentration of the disaster waste was investigated by sampling measurement and in-situ Ge measurement at 20 temporary disaster waste storages in Fukushima Prefecture excluding the evacuation zone and 'deliberate evacuation zone.' JNES carried out tins investigation upon a request from die Nuclear and Industrial Safety Agency. The investigation revealed that the measured radioactivity concentrations of the disaster waste lumps were enveloped within the soil monitoring readings in Fukushima Prefecture and also within a correlated curve between the air dose rates obtained from air dose rate readings around the disaster waste and the radioactivity concentrations of it. Based on the results of this study, JNES compiled a manual on measurement technique for contaminated disaster waste. (author)

Study on disaster waste around Fukushima Daiichi NPS

International Nuclear Information System (INIS)

2012-01-01

Extreme difficulties exists in Fukushima Prefecture in disposing of waste generated from the tsunami disaster (hereinafter referred to as disaster waste) and contaminated with radioactive material released from the crippled Fukushima Daiichi Nuclear Power Station. Although the waste should be treated according to the level of radioactivity, there were only air dose rates and radionuclide analyses of soil due to monitoring around the Fukushima Daiichi Nuclear Power Station and there had been no information on the radioactivity concentration of the disaster waste. The radioactivity concentration of the disaster waste was investigated by sampling measurement and in-situ Ge measurement at 20 temporary disaster waste storages in Fukushima Prefecture excluding the evacuation zone and 'deliberate evacuation zone.' JNES carried out tins investigation upon a request from die Nuclear and Industrial Safety Agency. The investigation revealed that the measured radioactivity concentrations of the disaster waste lumps were enveloped within the soil monitoring readings in Fukushima Prefecture and also within a correlated curve between the air dose rates obtained from air dose rate readings around the disaster waste and the radioactivity concentrations of it. Based on the results of this study, JNES compiled a manual on measurement technique for contaminated disaster waste. (author)

Addenda to the second update of the Fukushima Daiichi Nuclear Power Station accident. June 1 to August 31, 2011

International Nuclear Information System (INIS)

2011-01-01

These addenda provide the figures and tables for helping readers to understand the article titled 'the second update of the Fukushima Daiichi Nuclear Power Station (NPS) accident' by SHIBUTANI Yu. These figures and tables are mainly referred from 'Additional Report of the Japanese Government to the IAEA - The Accident at the Tokyo Electric Power Company Inc. (TEPCO) Fukushima Daiichi NPS - September 2011, Nuclear Emergency Response Headquarters Government of Japan' and the website of Prime Minster of Japan and His Cabinet, Nuclear and Industrial Safety Agency (NISA), Ministry of Education, Culture, Sports, Science and Technology (MEXT), TEPCO and Japan Atomic Industrial Forum Inc. (JAIF). The contents of this addenda cover (1) summary of 28 learned lessons, (2) status of each unit of Fukushima Daiichi NPS, (3) alternative core cooling system, (4) spent fuel pool alternative cooling system, (5) outline of waste water storage and treatment system, (6) prevention of environmental release of radioactive materials and monitoring, (7) environmental effect caused by the accident, and (8) influence of Fukushima Daiichi accident on electricity supply in Japan. (author)

Fukushima Daiichi - delivery of contaminated water into the Pacific ocean and possible consequences for the marine ecosystem; Fukushima Daiichi. Ableitungen und deren moegliche Auswirkungen in der Meeresumwelt

Energy Technology Data Exchange (ETDEWEB)

Nies, Hartmut [Bundesamt fuer Seeschifffahrt und Hydrographie (BSH), Hamburg (Germany). Abt. Meereskunde

2015-06-01

The nuclear power plant Fukushima Daiichi is sited at the coast of the Japanese island Honshu. Most of the cooling water for the three destroyed reactors units 1-3 and the nuclear fuel in the spent fuel pool of unit-4 were uncontrolled delivered into the groundwater and the Pacific Ocean. As a consequence high concentrations of I-131, Cs-134 and Cs-137 in the coastal waters have to be assumed. The contribution analyzed the possible consequences for the marine ecosystem. A drift time of 5 to 7 years toward the coast of North America is expected. The planning of the marine monitoring program MEXT is described. Radiation measurements in the coastal water up to 200 km distance from Daiichi were performed. The highest radionuclide concentrations of Cs-137 and Cs-134 were found in the fine grained sediments. No increased radioactivity in seafood is expected.

Light Water Reactor Sustainability Program, U.S. Efforts in Support of Examinations at Fukushima Daiichi-2017 Evaluations

Energy Technology Data Exchange (ETDEWEB)

Farmer, Mitchell T. [Argonne National Lab. (ANL), Argonne, IL (United States)

2017-08-01

Although the accident signatures from each unit at the Fukushima Daiichi Nuclear Power Station (NPS) [Daiichi] differ, much is not known about the end-state of core materials within these units. Some of this uncertainty can be attributed to a lack of information related to cooling system operation and cooling water injection. There is also uncertainty in our understanding of phenomena affecting: a) in-vessel core damage progression during severe accidents in boiling water reactors (BWRs), and b) accident progression after vessel failure (ex-vessel progression) for BWRs and Pressurized Water Reactors (PWRs). These uncertainties arise due to limited full scale prototypic data. Similar to what occurred after the accident at Three Mile Island Unit 2, these Daiichi units offer the international community a means to reduce such uncertainties by obtaining prototypic data from multiple full-scale BWR severe accidents. Information obtained from Daiichi is required to inform Decontamination and Decommissioning activities, improving the ability of the Tokyo Electric Power Company Holdings, Incorporated (TEPCO Holdings) to characterize potential hazards and to ensure the safety of workers involved with cleanup activities. This document, which has been updated to include FY2017 information, summarizes results from U.S. efforts to use information obtained by TEPCO Holdings to enhance the safety of existing and future nuclear power plant designs. This effort, which was initiated in 2014 by the Reactor Safety Technologies Pathway of the Department of Energy Office of Nuclear Energy Light Water Reactor (LWR) Sustainability Program, consists of a group of U.S. experts in LWR safety and plant operations that have identified examination needs and are evaluating TEPCO Holdings information from Daiichi that address these needs. Each year, annual reports include examples demonstrating that significant safety insights are being obtained in the areas of component performance, fission

JANSI’s Activities for Reflecting Lessons Learned from Fukushima Daiichi Accident

International Nuclear Information System (INIS)

Kugo, Akihide

2014-01-01

Conclusion: JANSI will continue to lay the groundwork for preventing an accident like the Fukushima Daiichi from ever happening again. JANSI will develop the system to provide an opportunity of “awareness” for operators to enhance nuclear safety and to follow-up their efforts continuously

The Fukushima Daiichi Accident. Technical Volume 4/5. Radiological Consequences

International Nuclear Information System (INIS)

2015-08-01

This technical volume describes the consequences associated with radioactivity and radiation from the accident at the Fukushima Daiichi nuclear power plant (NPP) for people and the environment. A number of international organizations have already issued reports on the potential health and environmental consequences of the accident, notably the World Health Organization (WHO) and the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The intention of the assessments presented in this volume is to build on their work, using more recent data where available. Quantitative information arising from both personal and environmental monitoring has been provided by the Government of Japan. Section 4.1 provides the best estimates of the magnitude and form of radioactive releases during the accident to the atmosphere and directly into the surrounding sea. It also explains the movement of the discharged radionuclides through air and water and the eventual deposition of the atmospheric activity on land in Japan and other countries worldwide, as well as on the open oceans. The goal is to provide a consolidated repository of information on releases to, and levels of radionuclides in, the environment. Some of this information is used in the analyses in subsequent sections of this volume. Section 4.2 gives an overview of exposures to the main groups of emergency workers at the Fukushima Daiichi NPP, to groups of off-site workers and to members of the public. Where sufficient data are available, average effective dose and thyroid equivalent doses derived from personal measurements are compared with the results of previous assessments for specific locations, population groups and time periods. Section 4.3 summarizes relevant aspects of the system of radiation protection in place at the time of the accident. It includes an overview of the legislation and guidance used to implement the radiation protection framework in Japan. This section also provides a

Impacts of the Fukushima Daiichi Accident on Nuclear Development Policies

International Nuclear Information System (INIS)

Vance, Robert; Henderson, David; ); Moore, Laurie

2017-01-01

The Fukushima Daiichi nuclear power plant accident has had an impact on the development of nuclear power around the world. While the accident was followed by thorough technical assessments of the safety of all operating nuclear power plants, and a general increase in safety requirements has been observed worldwide, national policy responses have been more varied. These responses have ranged from countries phasing out or accelerating decisions to phase out nuclear energy to countries reducing their reliance on nuclear power or on the contrary continuing to pursue or expand their nuclear power programs. This study examines changes to policies, and plans and attempts to distinguish the impact of the Fukushima Daiichi accident from other factors that have affected policy-making in relation to nuclear energy, in particular electricity market economics, financing challenges and competition from other sources (gas, coal and renewables). It also examines changes over time to long-term, quantitative country projections, which reveal interesting trends on the possible role of nuclear energy in future energy systems. (authors)

Research and development towards decommissioning of Fukushima Daiichi Nuclear Power Plants

International Nuclear Information System (INIS)

Minato, Kazuo

2013-01-01

Towards the decommissioning of Fukushima Daiichi Nuclear Power Plants, science-based research and development is important and useful, as well as technology and engineering development. Research and development activities based on radiation chemistry, radiochemistry, thermodynamics, etc., have contributed to safe and efficient decommissioning of the plants. (author)

Station black out of Fukushima Daiichi Nuclear Power Station Unit 1 was not caused by tsunamis

International Nuclear Information System (INIS)

Ito, Yoshinori

2013-01-01

Station black out (SBO) of Fukushima Daiichi Nuclear Power Station Unit 1 would be concluded to be caused before 15:37 on March 11, 2011 because losses of emergency ac power A system was in 15:36 and ac losses of B system in 15:37 according to the data published by Tokyo Electric Power Co. (TEPCO) in May 10, 2013. Tsunami attacked the site of Fukushima Daiichi Nuclear Power Station passed through the position of wave amplitude meter installed at 1.5 km off the coast after 15:35 and it was also recognized tsunami arrived at the coast of Unit 4 sea side area around in 15:37 judging from a series of photographs taken from the south side of the site and general knowledge of wave propagation. From a series of photographs and witness testimony, tsunami didn't attack Fukushima Daiichi Nuclear Power Station uniformly and tsunami's arrival time at the site of Unit 1 would be far later than arrival time at the coast of Unit 4 sea side area, which suggested it would be around in 15:39. TEPCO insisted tsunami passed through 1.5 km off the coast around in 15:33 and clock of wave amplitude meter was incorrect, which might be wrong. Thus SBO of Fukushima Daiichi Nuclear Power Station Unit 1 occurred before tsunami's arrival at the site of Unit 1 and was not caused by tsunami. (T. Tanaka)

NEA support to Fukushima Daiichi decommissioning strategy planning

International Nuclear Information System (INIS)

Weber, Inge; Otsuka, Ichiro; ); Sandberg, Nils; ); Funaki, Kentaro

2017-01-01

Six years after the Fukushima Daiichi nuclear power plant accident, the Japanese government and Tokyo Electric Power Holdings, Inc. (TEPCO) are shifting their focus to strategy planning for long-term challenges related to the decommissioning of the damaged reactors. The international community has been helping to address the unprecedented challenges of managing the accident facilities. The NEA is playing a key supporting and coordinating role in the international community, in particular in the area of radioactive waste management and the evaluation of the conditions and location of fuel debris. In the first half of 2017, a series of visual investigations using remotely controlled equipment and robots were performed to identify the condition of vessels inside, as well as the distribution of fuel debris in all three units. In the summer of 2017, as stated in the government road-map, policies for fuel debris retrieval from each unit would be presented, and would result in a discussion on which unit should be the first to undergo fuel debris retrieval in 2018. In addition, the basic policy for the processing and disposal of radioactive material arising from the accident would be conceptualised in the year 2017. This article highlights ongoing international joint activities within the NEA framework, corresponding to the challenges that have been identified in the Fukushima Daiichi decommissioning strategy planning

Evaluation of re-criticality potential in Fukushima Dai-ichi reactors following core damage accidents

Energy Technology Data Exchange (ETDEWEB)

NONE

2013-08-15

The re-criticality potential of the debris-bed, formed of the degraded core materials, cannot be ruled out during the cooling-down procedure of the Fukushima Dai-ichi NPPs. In this study the re-criticality potential has systematically investigated based on the core disruption phase analysis using a IMPACT-SAMPSON code prepared by The Institute of Applied Energy (IAE). The results obtained for the re-criticality potential, characterized by the eigen-values k-eff dependent on the debris composition formed at the core, RPV bottom, and PCV pedestal, are reflected to the arguments on the re-criticality prevention measures, such as timing and concentration of boron-compounds, during the cooling-down process of the Fukushima Dai-ichi NPPs. (author)

MDEP Design-Specific Common Position CP-EPRWG-02. Common position addressing Fukushima Daiichi-related issues

International Nuclear Information System (INIS)

2015-10-01

A severe accident involving several units took place in Japan at Fukushima Daiichi nuclear power plant (NPP) in March 2011. The immediate cause of the accident was an earthquake followed by a tsunami coupled with inadequate provisions against the consequences of such events in the design. Opportunities to improve protection against a realistic design basis tsunami were not taken. As a consequence of the tsunami, safety equipment and the related safety functions were lost at the plant, leading to core damage in three units and subsequently to large radioactive releases (INES 7). Several studies have already been performed to better understand the accident progression and detailed technical studies are still in progress in Japan and elsewhere. In the meantime, on-going studies on the behaviour of NPPs in very severe situations, similar to Fukushima Daiichi, seek to identify potential vulnerabilities in plant design and operation; to suggest reasonably practicable upgrades; or to recommend enhanced regulatory requirements and guidance to address such situations. Likewise, agencies around the world that are responsible for regulating the design, construction and operation of EPR plants are engaged in similar activities. The MDEP EPR Working Group (EPRWG) members consist of members from the United States, the United Kingdom, France, Finland, China, India and Sweden. Because not all of these countries have completed the regulatory review of their EPR applications yet, this paper identifies common preliminary approaches to address potential safety improvements for EPR plants, as well as common general expectations for new nuclear power plants, as related to lessons learned from the Fukushima Daiichi accident or Fukushima Daiichi-related issues. After the safety reviews of the EPR design applications that are currently in review are completed, the regulators will update this paper to reflect their safety conclusions regarding the EPR design and how the design could be

Outline of the Fukushima Daiichi Accident. Lessons Learned and Safety Enhancements

Directory of Open Access Journals (Sweden)

Hirano Masashi

2017-01-01

This paper briefly presents the outline of the Fukushima Daiichi accident and summarizes the major lessons learned having been drawn and safety enhancements having been done in Japan for the purpose of giving inputs to the discussions to be taken place in the Special Invited Session “Fukushima, 5 years after”.

Feature article. Fukushima Daiichi NPP accident

International Nuclear Information System (INIS)

Ekarinai, Masashi; Ake, Yutaka; Narabayashi, Tadashi

2011-01-01

This special feature article consisted of five reports and the minutes of emergency discussion meeting on Fukushima Daiichi Nuclear Power Plant (NPP) accident. Effects of the accident on future electricity supply of electric utilities and also on business development of nuclear industries were discussed. Activities of senior network team of atomic energy society of Japan (AESJ) to conduct severe accident analysis and early restoration from the accident were introduced. Circulating injection reactor cooling system and zeolite decontamination system of accumulated contaminated water was proposed. Effects of the accident on overseas reaction on nuclear development were also reported as well as personal experience of the professor in the US west coast on communications. (T. Tanaka)

A comparison of responses to the Fukushima Daiichi Nuclear Plant

International Nuclear Information System (INIS)

Oshima, Teruo

2011-01-01

Many Institutions abroad have expressed their views on the Fukushima Daiichi Nuclear Power Plant accident. When more emphasis on risk and precaution, they differ markedly from that in Japan. One of the main causes of the accident lies in disregard for prior warnings about possible tsunami risks. This paper will discuss lessons we can learn from the accident and future problems. (author)

Influence on UK Nuclear Regulation from the Fukushima Daiichi Accident

International Nuclear Information System (INIS)

Savage, R.

2016-01-01

This paper provides an overview of the UKs response to the Fukushima Daiichi Accident and highlights the influence that this has had on UK nuclear regulation since March 2011. ONR’s Incident Suite was staffed from the first day of the accident and remained active on a 24 hours basis for over two weeks. The purpose was to provide advice to the UK government specifically prompt assurance of why this accident couldn’t take place in the UK and practical advice in relation to the 17,000 UK nationals in Japan at that time. In the early phase of the accident ONR took part in international cooperation with the US, Canadian and French regulators in order to determine the actual technical status of the Fukushima Daiichi power plant units. The UK Secretary of State requested that the ONR Chief Inspector identify any lessons to be learnt by the UK nuclear industry and in doing so cooperate and coordinate with international colleagues. The Interim report was produced (May 2011) this focused on civil NPP’s, provided background to radiation, technology and regulations. This report compared the Japan situation with the UK and identified 11 conclusions and 26 recommendations.

Preliminary Assessment of the Possible BWR Core/Vessel Damage States for Fukushima Daiichi Station Blackout Scenarios Using RELAP/SCDAPSIM

Directory of Open Access Journals (Sweden)

C. M. Allison

2012-01-01

Full Text Available Immediately after the accident at Fukushima Daiichi, Innovative Systems Software and other members of the international SCDAP Development and Training Program started an assessment of the possible core/vessel damage states of the Fukushima Daiichi Units 1–3. The assessment included a brief review of relevant severe accident experiments and a series of detailed calculations using RELAP/SCDAPSIM. The calculations used a detailed RELAP/SCDAPSIM model of the Laguna Verde BWR vessel and related reactor cooling systems. The Laguna Verde models were provided by the Comision Nacional de Seguridad Nuclear y Salvaguardias, the Mexican nuclear regulatory authority. The initial assessment was originally presented to the International Atomic Energy Agency on March 21 to support their emergency response team and later to our Japanese members to support their Fukushima Daiichi specific analysis and model development.

The Fukushima Daiichi Accident. Report by the Director General [Chinese Version

International Nuclear Information System (INIS)

2015-08-01

This report presents an assessment of the causes and consequences of the accident at the Fukushima Daiichi nuclear power plant in Japan, which began on 11 March 2011. Caused by a huge tsunami that followed a massive earthquake, it was the worst accident at a nuclear power plant since the Chernobyl disaster in 1986. The report considers human, organizational and technical factors, and aims to provide an understanding of what happened, and why, so that the necessary lessons learned can be acted upon by governments, regulators and nuclear power plant operators throughout the world. Measures taken in response to the accident, both in Japan and internationally, are also examined. The Fukushima Daiichi Accident consists of a Report by the IAEA Director General and five technical volumes. It is the result of an extensive international collaborative effort involving five working groups with about 180 experts from 42 Member States with and without nuclear power programmes and several international bodies. It provides a description of the accident and its causes, evolution and consequences, based on the evaluation of data and information from a large number of sources available at the time of writing. The Fukushima Daiichi Accident will be of use to national authorities, international organizations, nuclear regulatory bodies, nuclear power plant operating organizations, designers of nuclear facilities and other experts in matters relating to nuclear power, as well as the wider public. The set contains six printed parts and five supplementary CD-ROMs. Contents: Report by the Director General; Technical Volume 1/5, Description and Context of the Accident; Technical Volume 2/5, Safety Assessment; Technical Volume 3/5, Emergency Preparedness and Response; Technical Volume 4/5, Radiological Consequences; Technical Volume 5/5, Post-accident Recovery; Annexes. The Report by the Director General is also available separately in Arabic, Chinese, English, French, Russian, Spanish and

The Fukushima Daiichi Accident. Report by the Director General [Japanese Version

International Nuclear Information System (INIS)

2015-08-01

This report presents an assessment of the causes and consequences of the accident at the Fukushima Daiichi nuclear power plant in Japan, which began on 11 March 2011. Caused by a huge tsunami that followed a massive earthquake, it was the worst accident at a nuclear power plant since the Chernobyl disaster in 1986. The report considers human, organizational and technical factors, and aims to provide an understanding of what happened, and why, so that the necessary lessons learned can be acted upon by governments, regulators and nuclear power plant operators throughout the world. Measures taken in response to the accident, both in Japan and internationally, are also examined. The Fukushima Daiichi Accident consists of a Report by the IAEA Director General and five technical volumes. It is the result of an extensive international collaborative effort involving five working groups with about 180 experts from 42 Member States with and without nuclear power programmes and several international bodies. It provides a description of the accident and its causes, evolution and consequences, based on the evaluation of data and information from a large number of sources available at the time of writing. The Fukushima Daiichi Accident will be of use to national authorities, international organizations, nuclear regulatory bodies, nuclear power plant operating organizations, designers of nuclear facilities and other experts in matters relating to nuclear power, as well as the wider public. The set contains six printed parts and five supplementary CD-ROMs. Contents: Report by the Director General; Technical Volume 1/5, Description and Context of the Accident; Technical Volume 2/5, Safety Assessment; Technical Volume 3/5, Emergency Preparedness and Response; Technical Volume 4/5, Radiological Consequences; Technical Volume 5/5, Post-accident Recovery; Annexes. The Report by the Director General is also available separately in Arabic, Chinese, English, French, Russian, Spanish and

The Fukushima Daiichi Accident. Report by the Director General [Spanish Version

International Nuclear Information System (INIS)

2015-08-01

This report presents an assessment of the causes and consequences of the accident at the Fukushima Daiichi nuclear power plant in Japan, which began on 11 March 2011. Caused by a huge tsunami that followed a massive earthquake, it was the worst accident at a nuclear power plant since the Chernobyl disaster in 1986. The report considers human, organizational and technical factors, and aims to provide an understanding of what happened, and why, so that the necessary lessons learned can be acted upon by governments, regulators and nuclear power plant operators throughout the world. Measures taken in response to the accident, both in Japan and internationally, are also examined. The Fukushima Daiichi Accident consists of a Report by the IAEA Director General and five technical volumes. It is the result of an extensive international collaborative effort involving five working groups with about 180 experts from 42 Member States with and without nuclear power programmes and several international bodies. It provides a description of the accident and its causes, evolution and consequences, based on the evaluation of data and information from a large number of sources available at the time of writing. The Fukushima Daiichi Accident will be of use to national authorities, international organizations, nuclear regulatory bodies, nuclear power plant operating organizations, designers of nuclear facilities and other experts in matters relating to nuclear power, as well as the wider public. The set contains six printed parts and five supplementary CD-ROMs. Contents: Report by the Director General; Technical Volume 1/5, Description and Context of the Accident; Technical Volume 2/5, Safety Assessment; Technical Volume 3/5, Emergency Preparedness and Response; Technical Volume 4/5, Radiological Consequences; Technical Volume 5/5, Post-accident Recovery; Annexes. The Report by the Director General is also available separately in Arabic, Chinese, English, French, Russian, Spanish and

The Fukushima Daiichi Accident. Report by the Director General [Russian Version

International Nuclear Information System (INIS)

2015-08-01

This report presents an assessment of the causes and consequences of the accident at the Fukushima Daiichi nuclear power plant in Japan, which began on 11 March 2011. Caused by a huge tsunami that followed a massive earthquake, it was the worst accident at a nuclear power plant since the Chernobyl disaster in 1986. The report considers human, organizational and technical factors, and aims to provide an understanding of what happened, and why, so that the necessary lessons learned can be acted upon by governments, regulators and nuclear power plant operators throughout the world. Measures taken in response to the accident, both in Japan and internationally, are also examined. The Fukushima Daiichi Accident consists of a Report by the IAEA Director General and five technical volumes. It is the result of an extensive international collaborative effort involving five working groups with about 180 experts from 42 Member States with and without nuclear power programmes and several international bodies. It provides a description of the accident and its causes, evolution and consequences, based on the evaluation of data and information from a large number of sources available at the time of writing. The Fukushima Daiichi Accident will be of use to national authorities, international organizations, nuclear regulatory bodies, nuclear power plant operating organizations, designers of nuclear facilities and other experts in matters relating to nuclear power, as well as the wider public. The set contains six printed parts and five supplementary CD-ROMs. Contents: Report by the Director General; Technical Volume 1/5, Description and Context of the Accident; Technical Volume 2/5, Safety Assessment; Technical Volume 3/5, Emergency Preparedness and Response; Technical Volume 4/5, Radiological Consequences; Technical Volume 5/5, Post-accident Recovery; Annexes. The Report by the Director General is also available separately in Arabic, Chinese, English, French, Russian, Spanish and

Response to the accident at TEPCO's Fukushima Daiichi Nuclear Power Plants

International Nuclear Information System (INIS)

Nei, Hisanori

2012-01-01

This article was reading from the author's plenary lecture at the thermal and nuclear power generation convention 2011, which was summary of the author edited report of Japanese government to IAEA ministerial conference on nuclear safety. The article consisted of (1) outlines of occurrence and development of the accident at TEPCO's Fukushima Daiichi Nuclear Power Plants (NPPs), (2) comparison of Fukushima Daiichi NPPs with other NPPs (Fukushima Daini, Onagawa and Tokai Daini NPPs), (3) major countermeasures to settle the situation regarding the accident, (4) comprehensive safety evaluation of other NPPs as response to the accident and (5) lessons learned from the accident so far. It was highly important to ensure power supplies and robust cooling functions of reactors, pressure containment vessels and spent fuel pools. 28 lessons were categorized into five groups such as (1) strengthen preventive measures against a severe accident, (2) enhancement of response measures against severe accidents, (3) enhancement of nuclear emergency responses, (4) reinforcement of safety infrastructure and (5) thoroughness of safety culture. (T. Tanaka)

Analysis of accident progression in the TEPCO Fukushima Daiichi Nuclear Power Station

Energy Technology Data Exchange (ETDEWEB)

NONE

2013-08-15

One of the objectives of this study is to investigate the early stage of the TEPCO Fukushima Daiichi accident and to check the validity of the countermeasures against the accident. Last year the early stage of the accident was analyzed with use of RELAP5 code, and the longer term analysis was done by MELCOR code. This year, the simulation of reactor water level instrumentation behavior by MELCOR code was performed. Another objective of this study is to analyze of the long term cooling after the Fukushima Daiichi accident by TRACE5 code. In order to simulate the cooling conditions in Fukushima plants after the accident, the parametric calculations were done on the assumption of the existence of steam/liquid leak in Reactor Pressure Vessel (RPV) and Pressure Containment Vessel (PCV) and the variety of debris distribution in RPV and PCV. As a result, the debris distribution in RPV and PCV was estimated by referring plant parameter such as reactor pressure and temperature. (author)

Japan Catastrophic Earthquake and Tsunami in Fukushima Daiichi NPP; Is it Beyond Design Basis Accident or a Design Deficiency and Operator Unawareness?

International Nuclear Information System (INIS)

Gaafar, M.A.; Refeat, R.M.; EL-Kady, A.A.

2012-01-01

On March 11, 2011 a catastrophic earthquake and tsunami struck the north east coast of Japan. This catastrophe damaged fully or partially the six units of the Fukushima Daiichi Nuclear Power Plant.Questions were raised following the aftermath, whether it is beyond design basis accident caused by severe natural event or a failure by the Japanese authorities to plan to deal with such accident. There are many indications that the Utility of Fukushima Daiichi NPP, Tokyo Electric Power Company (TEPCO), did not pay enough attention to numerous facts about the incompatibility of the site and several design defects in the plant units. In fact there are three other NPP sites nearby Fukushima Daiichi Plant (about 30 to 60 Km far from Fukushima Daiichi NPP), with different site characteristics, which survived the same catastrophic earthquake and tsunami, but they were automatically turned into a safe shutdown state. These plants sites are Fukushima Daini Plant (4 units), Onagawa Plant (3 units) and Tokai Daini (II) Plant (one unit). In this paper, the aftermath Fukushima Daiichi plant integrity is pointed out. Some facts about the site and design concerns which could have implications on the accident are discussed. The response of Japan Authority is outlined and some remarks about their actions are underlined. The impacts of this disaster on the Nuclear Power Program worldwide are also discussed.

Study on public awareness of utilizing nuclear power in China. Changes in public awareness after the accident of Fukushima Daiichi Nuclear Power Plants

International Nuclear Information System (INIS)

Xu, Ting; Wakabayashi, Toshio

2012-01-01

The purpose of this study is to clarify public awareness of utilizing nuclear power in China and to determine the effects of the accident of Fukushima Daiichi nuclear power plants. Web online surveys were carried out before and after the accident of Fukushima Daiichi nuclear power plants. The online survey before the accident of Fukushima Daiichi nuclear power plants had 4,255 adult respondents consisting of 1,851 males and 2,404 females. The online survey after the accident had 721 respondents consisting of 406 males and 315 females. The two online surveys about the attitude toward nuclear power plants consisted of 37 items, such as the necessity of nuclear power plants, the reliability of safety, and government confidence. As a result, respondents of the online surveys in China consider that nuclear energy is more important than the anxiety of accident. On the other hand, women have sensation of fear for the accident of Fukushima Daiichi nuclear power plants and radiation. (author)

Fukushima Daiichi: implications for carbon-free energy, nuclear nonproliferation, and community resilience.

Science.gov (United States)

Hall, Howard L

2011-07-01

Implications of the nuclear power plant accidents at Fukushima Daiichi are explored in this commentary. In addition to questions of nuclear reactor regulatory standards, broader implications on noncarbon-emitting energy production, nuclear nonproliferation objectives, and community resilience and emergency response against catastrophic events are explored. Copyright © 2011 SETAC.

Analysis of Fukushima Daiichi Nuclear Power Station severe accident using MAAP4.05

International Nuclear Information System (INIS)

Yoo, Jae S.; Suh, Kune Y.; Kim, Dong M.

2011-01-01

Rather extensive reactor core meltdown and partial melt-through that took place at the Fukushima Daiichi nuclear power plants (NPPs) on March 11, 2011 had been caused by a massive earthquake followed by tsunami rarely seen in history. The happening had turned into an unprecedented serious accident since the Chernobyl Unit 4 in 1986 that extended over multiple reactors simultaneously. A previous documentary survey, NUREG-1150 report provides significant insights into how a severe accident might develop at a boiling water reactor (BWR) and the range of consequences. NUREG-1150 did identify the importance of loss of power accidents for a BWR. This paper describes recent analyses of the Fukushima Daiichi NPPs severe accident. Calculations were performed with the MAAP4.05 code by modifying the parameter file for the Peach Bottom Unit 2, a BWR 4 type in the Mark-I containment. Generally this is the same type of reactor as Fukushima Daiichi Units 2 and 3. This resulted in good understanding of the response of this type of early BWRs to prolonged loss of diesel generators and batteries. There is clearly vulnerability with this early type of BWRs which would be less onerous than later existing plant and new build designs. This analysis, however, was based on rather limited amount of information obtained at the time of preparing this report and adopted various estimates and assumptions for conditions necessary to run the analysis. Hence there persists considerable uncertainty in the results. MAAP4.05 was run pursuant to the observed data and chronology of Fukushima Daiichi Units 1 through 3 reported by the Tokyo Electric Power Company (TEPCO) as well as the Japanese Government. Severe accident scenarios have not only gone far beyond the design basis, but also exceeded the extent of multiple breakdowns assumed in the preparation for such accident management measures as the malfunction or loss of all the emergency core cooling system (ECCS) combined with the extended loss of

The Fukushima Daiichi Accident. Technical Volume 4/5. Radiological Consequences. Annexes

International Nuclear Information System (INIS)

2015-08-01

The Fukushima Daiichi Accident consists of a Report by the IAEA Director General and five technical volumes. It is the result of an extensive international collaborative effort involving five working groups with about 180 experts from 42 Member States with and without nuclear power programmes and several international bodies. It provides a description of the accident and its causes, evolution and consequences, based on the evaluation of data and information from a large number of sources available at the time of writing. The Fukushima Daiichi Accident will be of use to national authorities, international organizations, nuclear regulatory bodies, nuclear power plant operating organizations, designers of nuclear facilities and other experts in matters relating to nuclear power, as well as the wider public. The set contains six printed parts and five supplementary CD-ROMs. Contents: Report by the Director General; Technical Volume 1/5, Description and Context of the Accident; Technical Volume 2/5, Safety Assessment; Technical Volume 3/5, Emergency Preparedness and Response; Technical Volume 4/5, Radiological Consequences; Technical Volume 5/5, Post-accident Recovery; Annexes. The Report by the Director General is available separately in Arabic, Chinese, English, French, Russian, Spanish and Japanese

Thermal stratification in a scaled-down suppression pool of the Fukushima Daiichi nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Jo, Byeongnam, E-mail: jo@vis.t.u-tokyo.ac.jp [Nuclear Professional School, The University of Tokyo, 2-22 Shirakata, Tokai-mura, Ibaraki 319-1188 (Japan); Erkan, Nejdet [Nuclear Professional School, The University of Tokyo, 2-22 Shirakata, Tokai-mura, Ibaraki 319-1188 (Japan); Takahashi, Shinji [Department of Nuclear Engineering and Management, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Song, Daehun [Nuclear Professional School, The University of Tokyo, 2-22 Shirakata, Tokai-mura, Ibaraki 319-1188 (Japan); Hyundai and Kia Corporate R& D Division, Hyundai Motors, 772-1, Jangduk-dong, Hwaseong-Si, Gyeonggi-Do 445-706 (Korea, Republic of); Sagawa, Wataru; Okamoto, Koji [Nuclear Professional School, The University of Tokyo, 2-22 Shirakata, Tokai-mura, Ibaraki 319-1188 (Japan)

2016-08-15

Highlights: • Thermal stratification was reproduced in a scaled-down suppression pool of the Fukushima Daiichi nuclear power plants. • Horizontal temperature profiles were uniform in the toroidal suppression pool. • Subcooling-steam flow rate map of thermal stratification was obtained. • Steam bubble-induced flow model in suppression pool was suggested. • Bubble frequency strongly depends on the steam flow rate. - Abstract: Thermal stratification in the suppression pool of the Fukushima Daiichi nuclear power plants was experimentally investigated in sub-atmospheric pressure conditions using a 1/20 scale torus shaped setup. The thermal stratification was reproduced in the scaled-down suppression pool and the effect of the steam flow rate on different thermal stratification behaviors was examined for a wide range of steam flow rates. A sparger-type steam injection pipe that emulated Fukushima Daiichi Unit 3 (F1U3) was used. The steam was injected horizontally through 132 holes. The development (formation and disappearance) of thermal stratification was significantly affected by the steam flow rate. Interestingly, the thermal stratification in the suppression pool vanished when subcooling became lower than approximately 5 °C. This occurred because steam bubbles are not well condensed at low subcooling temperatures; therefore, those bubbles generate significant upward momentum, leading to mixing of the water in the suppression pool.

Radioactive pollution from Fukushima Daiichi nuclear power plant in the terrestrial environment.

Science.gov (United States)

Tazoe, H; Hosoda, M; Sorimachi, A; Nakata, A; Yoshida, M A; Tokonami, S; Yamada, M

2012-11-01

Major contaminants from venting and hydrogen explosions at the Fukushima Daiichi nuclear reactors between 12 and 15 March 2011 were transported northwestward and deposited on soil and plants via precipitation. Surface soils and plant leaves were sampled at 64 sites in the Fukushima Prefecture. The highest concentrations of (134)Cs (84.4 kBq kg(-1)) and (137)Cs (82.0 kBq kg(-1)) in surface soils were observed at Nagadoro in Iidate village located 32 km northwest from the Fukushima Daiichi nuclear power plant. Furthermore, (131)I, (129)Te, (129 m)Te, (110 m)Ag and (140)La were detected in the same samples. Outer surface of plant leaves, such as bamboo, cabbage and grasses were highly contaminated at the high-dose rate areas of Tsushima and Minami-Tsushima in Namie town. Mugwort leaves that grew after the pollution event had extremely low concentration of radionuclides; however, the plant/soil radiocaesium ratio was 0.023 ± 0.006. It is anticipated that decomposition of fallen leaves will promote recycling of radionuclides in the environment.

What happened at Fukushima Daiichi Nuclear Power Plants. Verification of effects of earthquake and resulting tsunami

International Nuclear Information System (INIS)

Yamazaki, Tatsuhiro

2012-01-01

At 14:46 on March 11, 2011, the Tohoku District-off the Pacific Ocean Earthquake occurred. The magnitude of this earthquake was 9.0, the largest in Japan's recorded history, and afterwards enormous tsunami struck the Pacific coast of Tohoku District. This great earthquake and resulting tsunami struck the Fukushima Daiichi Nuclear Power Plants (NPPs) of Tokyo Electric Power Co. (TEPCO), whose cooling function was lost and suffered a severe nuclear accident. This article described the mechanism and safety measure of BWR type NPPs and verified how the great earthquake and resulting tsunami affected NPPs. Progression of the accident at Fukushima Daiichi NPPs was outlined. Damage by the earthquake could not be fully inspected but might not be significant to safety systems. However, the earthquake of longer duration time as much as about 250 sec caused failure of breaker or lightening arrester and also damage on electric facility such as transmission line insulator. Tsunami or inundation height was as high as O.P. (Onahama Pile) +11.5-15.5 m for Unit 1-4 reactor area while designed as O.P. +5.7 m, which caused blackout (power outage) and a reactor core meltdown at Fukushima Daiichi NPPs. (T. Tanaka)

Emergency operating procedures improvement based on the lesson learned from the Fukushima Daiichi accident

Energy Technology Data Exchange (ETDEWEB)

Wu, Wen-Hsiung, E-mail: whwu1127@aec.gov.tw [Atomic Energy Council, 2F., No. 80, Sec.1, Chenggong Rd., Yonghe Dist., New Taipei City 234, Taiwan (China); Institute of Nuclear Engineering and Science, National Tsing Hua University, No. 101, Sec. 2, Guangfu Rd., Hsinchu City 300, Taiwan (China); Liao, Lih-Yih, E-mail: lyliao@iner.gov.tw [Institute of Nuclear Energy Research, Atomic Energy Council, No. 1000, Wenhua Rd., Jiaan Village, Longtan Township, Taoyuan County 325, Taiwan (China)

2016-12-01

Highlights: • Discuss the problem of EOPs at the time of Fukushima accident to deal with the prolonged SBO. • Elaborate the potential risk accompanied with the emergency depressurization in the SBO. • Describe a special guideline to cope with Fukushima-like accidents and provide its technical basis. • Point out that Fukushima accident might have been prevented if improved EOPs had been used. • Propose key points and suggestions for improving the EOPs. - Abstract: One of the lessons learned from the Fukushima Daiichi accident is the emergency operating procedures (EOPs) have to be improved. The BWR Owners’ Group revised the emergency procedure guidelines and addressed the lesson learned from the Fukushima Daiichi accident in revision 3 in order to avoid loss of turbine-driven makeup water systems during reactor depressurization. However, the improvement deserves much more attention. The existing EOPs at the time of the accident may not be adequate enough for the prolonged station blackout condition, because resources required for performing the EOPs are vastly unavailable or gradually exhausted. The improved EOPs must not only permit early reactor pressure vessel depressurization, but also address the risk accompanied with the emergency depressurization. For this reason, Taiwan Power Company proposed the Ultimate Response Guideline (URG) to cope with Fukushima-like accidents. The main content of the URG is a two-stage depressurization strategy, namely the controlled depressurization and the emergency depressurization. The technical basis of the two-stage depressurization strategy was discussed in this paper. The effectiveness of the URG was verified by using TRAC/RELAP Advanced Computational Engine (TRACE). Besides, the emergency responses performed by Fukushima Daini nuclear power plant (Fukushima Daini NPP) were found to be very similar to the URG. The consequences of Fukushima Daini NPP somehow demonstrate that the URG is effective for Fukushima

Emergency operating procedures improvement based on the lesson learned from the Fukushima Daiichi accident

International Nuclear Information System (INIS)

Wu, Wen-Hsiung; Liao, Lih-Yih

2016-01-01

Highlights: • Discuss the problem of EOPs at the time of Fukushima accident to deal with the prolonged SBO. • Elaborate the potential risk accompanied with the emergency depressurization in the SBO. • Describe a special guideline to cope with Fukushima-like accidents and provide its technical basis. • Point out that Fukushima accident might have been prevented if improved EOPs had been used. • Propose key points and suggestions for improving the EOPs. - Abstract: One of the lessons learned from the Fukushima Daiichi accident is the emergency operating procedures (EOPs) have to be improved. The BWR Owners’ Group revised the emergency procedure guidelines and addressed the lesson learned from the Fukushima Daiichi accident in revision 3 in order to avoid loss of turbine-driven makeup water systems during reactor depressurization. However, the improvement deserves much more attention. The existing EOPs at the time of the accident may not be adequate enough for the prolonged station blackout condition, because resources required for performing the EOPs are vastly unavailable or gradually exhausted. The improved EOPs must not only permit early reactor pressure vessel depressurization, but also address the risk accompanied with the emergency depressurization. For this reason, Taiwan Power Company proposed the Ultimate Response Guideline (URG) to cope with Fukushima-like accidents. The main content of the URG is a two-stage depressurization strategy, namely the controlled depressurization and the emergency depressurization. The technical basis of the two-stage depressurization strategy was discussed in this paper. The effectiveness of the URG was verified by using TRAC/RELAP Advanced Computational Engine (TRACE). Besides, the emergency responses performed by Fukushima Daini nuclear power plant (Fukushima Daini NPP) were found to be very similar to the URG. The consequences of Fukushima Daini NPP somehow demonstrate that the URG is effective for Fukushima

Construction of Daiichi Tamagawa bridge; Daiichi Tamagawa kyoryo no seko

Energy Technology Data Exchange (ETDEWEB)

Watanabe, O.; Tsuyoshi, T. [East Japan Railway Company, Tokyo (Japan); Ota, T.; Sato, S. [Tekken Corp., Tokyo (Japan)

1997-05-30

This paper describes the construction of Daiichi Tamagawa Bridge for JR Tazawako Line, which was reconstructed with the Akita Shinkansen Project apart from the existing line. This bridge is a three-span continuous PC cable stayed bridge. To avoid operation accidents due to snow and ice, independent two-column type with a height of 11 m without beam was employed for the main tower. For the construction of upper part, overhang election construction method was adopted, which can be applied all the year round. The main girder has a single box cross section, and a width of 5.5 m and a beam height of 2.3 m. This was also constructed by the overhang construction method. To reduce the construction period, the main tower was constructed by the precast block construction method. The whole bridge was divided into six blocks by considering the hoist performance of cranes. Reinforcement against bearing pressure and cleavage due to the cable tensile force was conducted by adopting saddle structure for the main tower. Oblique members were jointed with the main girder using lateral beams projected from lateral side of girder. Totally seven PC cables were used for each oblique member. Measurements and management during the overhang construction were also described. The construction was over without problems in August, 1996. This bridge is under test operation using test run vehicles. 2 refs., 20 figs., 7 tabs.

Current status and future planning of Fukushima Daiichi Nuclear Power Station after Great East Japan earthquake

International Nuclear Information System (INIS)

Inouer, Y.

2012-01-01

Fukushima Daiichi Nuclear Power Station (NPS) clean-up and decommissioning activities require a lot of R and D and careful project management due to its severity of damage. Inability of access inside the reactor and turbine buildings due to harsh environment results in large uncertainties which make the project planning difficult R and R activities will be conducted in parallel with on-site clean-up and maintenance activities. In order to cope with this unprecedented challenge, the government, laboratories, academicians, vendors, manufacturers, and other partners have joined together to support tokyo electric Power Company, Inc (TEPCO). This paper will summarize the current status and mid-and long-term plan for the clean-up and decommissioning of Units 1 to 4 of Fukushima Daiichi NPS as of March, 2012. (Author) 15 refs.

The Fukushima Daiichi nuclear disaster: a brief report

International Nuclear Information System (INIS)

Yadav, Roopaksh; Joshi, Pankaj Kumar

2012-01-01

Fukushima Daiichi is a series of equipment failures, nuclear meltdown and release of radioactive materials at the Fukushima -1 nuclear power plant, following the Tohoku earthquake and tsunami. The plant comprises six separate boiling water reactors originally designed by general electric and maintained by the Tokyo Electric Power Company (TEPCO). The Fukushima disaster is the building may be causing isolated, uncontrolled nuclear chain reaction. TEPCO confirmed its concern about the accuracy of high iodine and chlorine report by formally retracting the report which eliminated both the exceptionally high iodine-134 and chlorine-38 levels as proof of criticality. Reports of 13 observation of neutron beams 1.5 km. 'southwest of the plant's no. 1 and 2 reactors' from 13 to 16 March raised the possibility the nuclear fission could have occurred after the initial scraming of the reactors at Fukushima Daiichi. 16 March reports that fuel rods in the spent fuel pool at unit 4 could have been exposed to air appeared to indicate the fission may have occurred in that fuel pool. Later reports of exceptionally high iodine-134 levels appeared to confirm this theory because very high levels of iodine-134 would be indicative of fission reactions. The same report also showed high measurements of chlorine-38, which some nuclear experts used to calculate that fission must be occurring in unit 1. Despite TEPCO suggesting the iodine-134 report was inaccurate, the IAEA appeared to accept the chlorine-based analysis as a valid theory suggesting fission when it stated at a press conference that Melted fuel in the no. 1 reactor as of September 2011, there were no deaths or serious injuries due to direct radiation. Cancer deaths due to accumulated radiation exposure cannot be ruled out and according to one expert, might be in the order of 100 cases. (author)

Insights Gained from Forensic Analysis with MELCOR of the Fukushima-Daiichi Accidents.

Energy Technology Data Exchange (ETDEWEB)

Andrews, Nathan C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gauntt, Randall O. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-10-01

Since the accidents at Fukushima-Daiichi, Sandia National Laboratories has been modeling these accident scenarios using the severe accident analysis code, MELCOR. MELCOR is a widely used computer code developed at Sandia National Laboratories since ~1982 for the U.S. Nuclear Regulatory Commission. Insights from the modeling of these accidents is being used to better inform future code development and potentially improved accident management. To date, our necessity to better capture in-vessel thermal-hydraulic and ex-vessel melt coolability and concrete interactions has led to the implementation of new models. The most recent analyses, presented in this paper, have been in support of the of the Organization for Economic Cooperation and Development Nuclear Energy Agency’s (OECD/NEA) Benchmark Study of the Accident at the Fukushima Daiichi Nuclear Power Station (BSAF) Project. The goal of this project is to accurately capture the source term from all three releases and then model the atmospheric dispersion. In order to do this, a forensic approach is being used in which available plant data and release timings is being used to inform the modeled MELCOR accident scenario. For example, containment failures, core slumping events and lower head failure timings are all enforced parameters in these analyses. This approach is fundamentally different from a blind code assessment analysis often used in standard problem exercises. The timings of these events are informed by representative spikes or decreases in plant data. The combination of improvements to the MELCOR source code resulting from analysis previous accident analysis and this forensic approach has allowed Sandia to generate representative and plausible source terms for all three accidents at Fukushima Daiichi out to three weeks after the accident to capture both early and late releases. In particular, using the source terms developed by MELCOR, the MACCS software code, which models atmospheric dispersion and

Corium Configuration and Penetration Tube Failure for Fukushima Daiichi Nuclear Power Plant

International Nuclear Information System (INIS)

An, Sang Mo; Lee, Jae Bong; Kim, Hwan Yeol; Song, Jin Ho

2016-01-01

For the LWRs (light water reactors), the penetration tubes at the reactor vessel lower head are regarded as the most vulnerable structures along with a global vessel failure during a severe accident because they can be seriously damaged by a corium melt or debris relocated into the lower plenum of the vessel. The research on the penetration tube failure is of higher importance in the BWRs, as it could lead to melt discharge into the containment and subsequent release of radioactive materials to the environment due to the containment failure. There are more than one hundred of penetration tubes in the Fukushima Daiichi NPPs (nuclear power plants), such as ICM-GTs (in-core monitoring guide tubes), CRGTs (control rod guide tubes) and drain tubes. The ICM-GTs include SRMs (source range monitors), IRMs (intermediate range monitors), LPRMs (local power range monitors) and TIPs (traversing in-core probes), which are much thinner than other tubes. The experimental researches to investigate the corium configuration and the penetration tube failure for the Fukushima Daiichi NPPs were introduced and some meaningful results were summarized. It was shown that the corium ingot was separated into two layers, of which the upper layer was metal-rich while the lower one was oxide-rich. It seemed that B 4 C would contribute to reducing the density of the metallic melt. The two-layered configuration will provide useful information to understand the core melt progression and post-recovery actions for the Fukushima Daiichi NPPs. In addition, we performed a large scale penetration tube failure experiment for the SRM/IRM guide tube, and showed high possibilities of large amount of corium discharge out of the reactor vessel lower head, which followed by the tube melting in a very short time. We are planning to perform the penetration tube failure experiments for another dry tube of ICM-GT (LPRM guide tube), and later for the wet tube (CRGT)

Corium Configuration and Penetration Tube Failure for Fukushima Daiichi Nuclear Power Plant

Energy Technology Data Exchange (ETDEWEB)

An, Sang Mo; Lee, Jae Bong; Kim, Hwan Yeol; Song, Jin Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

For the LWRs (light water reactors), the penetration tubes at the reactor vessel lower head are regarded as the most vulnerable structures along with a global vessel failure during a severe accident because they can be seriously damaged by a corium melt or debris relocated into the lower plenum of the vessel. The research on the penetration tube failure is of higher importance in the BWRs, as it could lead to melt discharge into the containment and subsequent release of radioactive materials to the environment due to the containment failure. There are more than one hundred of penetration tubes in the Fukushima Daiichi NPPs (nuclear power plants), such as ICM-GTs (in-core monitoring guide tubes), CRGTs (control rod guide tubes) and drain tubes. The ICM-GTs include SRMs (source range monitors), IRMs (intermediate range monitors), LPRMs (local power range monitors) and TIPs (traversing in-core probes), which are much thinner than other tubes. The experimental researches to investigate the corium configuration and the penetration tube failure for the Fukushima Daiichi NPPs were introduced and some meaningful results were summarized. It was shown that the corium ingot was separated into two layers, of which the upper layer was metal-rich while the lower one was oxide-rich. It seemed that B{sub 4}C would contribute to reducing the density of the metallic melt. The two-layered configuration will provide useful information to understand the core melt progression and post-recovery actions for the Fukushima Daiichi NPPs. In addition, we performed a large scale penetration tube failure experiment for the SRM/IRM guide tube, and showed high possibilities of large amount of corium discharge out of the reactor vessel lower head, which followed by the tube melting in a very short time. We are planning to perform the penetration tube failure experiments for another dry tube of ICM-GT (LPRM guide tube), and later for the wet tube (CRGT)

Assistance to the Fukushima Daiichi NPP accident

International Nuclear Information System (INIS)

Sakuma, Minoru

2012-01-01

Immediately after the reactor accident of Fukushima Daiichi Nuclear Power Plant occurring on March 11, 2011, JAEA started and continues to work with its every possible effort for remediation and has established the head quarter for countermeasure in Fukushima prefecture. The present paper includes main activities of assisting Fukushima area such as environmental monitoring and decontamination, technical advises to Japanese and local government, and others. Some are in cooperation with universities and others with Tokyo Electric Power Company. Towards closing the reactor accident, JAEA is joining the integrated activities for cooling the damaged reactor core and management of storing and disposal of radioactive wastes produced and large amount of remaining contaminated water to find out an adequate method for decontamination and preparing the manual for it. (S. Ohno)

Analysis of comparative English media reports about the aftermath of the Fukushima Daiichi Nuclear Power Plant disaster

International Nuclear Information System (INIS)

Sakai, Makoto

2015-01-01

I performed a comparative analysis of media reports that related to the aftermath of the Fukushima Daiichi nuclear power plant disaster. I researched advanced countries' media reports on the nuclear power technology field, and especially those from the United States, the United Kingdom, Germany, and France. For this research, I gathered news texts on the aftermath of the Fukushima Daiichi nuclear power plant disaster from newspapers and websites. Then I categorized them into four groups, to analyze what the media in the above four counties have reported about Fukushima: 'same context' (typical context), 'a different context from other countries' media', 'a changing context from before', and 'proposals for the decommissioning and reconstruction process in Japan'. (author)

Fukushima Daiichi nuclear acccident. Damaged facilities of the site - Situation as on March 2018

International Nuclear Information System (INIS)

2018-03-01

After a recall of the events that led to the Fukushima Daiichi accident, this note presents the situation in March 2018 of the actions of control of the damaged facilities and of their effluents. The last part presents the three steps of the facility control recovery plan retained by TEPCO

Hydrogen combustion in a flat semi-confined layer with respect to the Fukushima Daiichi accident

International Nuclear Information System (INIS)

Kuznetsov, M.; Yanez, J.; Grune, J.; Friedrich, A.; Jordan, T.

2012-01-01

The hydrogen accumulation at the top of containment or reactor building may occur due to an interaction of molten corium and water followed by a severe accident of a nuclear reactor (TMI, Chernobyl, Fukushima Daiichi). The hydrogen, released from the reactor, accumulates usually as a stratified semi-confined layer of hydrogen-air mixture. A series of large scale experiments on hydrogen combustion and explosion in a semi-confined layer of uniform and non-uniform hydrogen-air mixtures in presence of obstructions or without them was performed at the Karlsruhe Inst. of Technology (KIT). Different flame propagation regimes from slow subsonic to relative fast sonic flames and then to the detonations were experimentally investigated in different geometries and then simulated with COMSD code with respect to evaluate amount of burnt hydrogen taken place during the Fukushima Daiichi Accident (FDA). The experiments were performed in a horizontal semi-confined layer with dimensions of 9x3x0.6 m with/without obstacles opened from below. The hydrogen concentration in the mixtures with air was varied in the range of 0-34 vol. % without or with a gradient of 0-60 vol. %H 2 /m. Effects of hydrogen concentration gradient, thickness of the layer, geometry of the obstructions, average and maximum hydrogen concentration on flame propagation regimes were investigated with respect to evaluate the maximum pressure loads of internal structures. Blast wave strength and dynamics of propagation after explosion of the layer of hydrogen-air mixture was numerically simulated to reproduce the hydrogen explosion process during the Fukushima Daiichi Accident. (authors)

Precept from the management for the accident of Fukushima daiichi

International Nuclear Information System (INIS)

Miyaushiro, Norihiro

2013-01-01

At 17 hours after the accident of Fukushima Daiichi Nuclear Power Plant due to the Great East Japan Earthquake, National Institute of Radiological Sciences sent the first REMAT (Radiation Emergency Medical Assistance Team) in the 20 km range from the Plant. The team members were confronted by two issues: (1) Medical activities under the infrastructures destructed by a multiple disaster caused by earthquake, tsunami and nuclear accident, which was not presumed. (2) Radiation protection management for dispatched staff. Measures for this situation worked out by activities on the site are presented. (K.Y.)

The Fukushima Daiichi Accident. Technical Volume 3/5. Emergency Preparedness and Response. Annexes

International Nuclear Information System (INIS)

2015-08-01

The Fukushima Daiichi Accident consists of a Report by the IAEA Director General and five technical volumes. It is the result of an extensive international collaborative effort involving five working groups with about 180 experts from 42 Member States with and without nuclear power programmes and several international bodies. It provides a description of the accident and its causes, evolution and consequences, based on the evaluation of data and information from a large number of sources available at the time of writing. The Fukushima Daiichi Accident will be of use to national authorities, international organizations, nuclear regulatory bodies, nuclear power plant operating organizations, designers of nuclear facilities and other experts in matters relating to nuclear power, as well as the wider public. The set contains six printed parts and five supplementary CD-ROMs. Contents: Report by the Director General; Technical Volume 1/5, Description and Context of the Accident; Technical Volume 2/5, Safety Assessment; Technical Volume 3/5, Emergency Preparedness and Response; Technical Volume 4/5, Radiological Consequences; Technical Volume 5/5, Post-accident Recovery; Annexes. The Report by the Director General is available separately in Arabic, Chinese, English, French, Russian, Spanish and Japanese

Peace Education, Domestic Tranquility, and Democracy: The Fukushima Daiichi Nuclear Disaster as Domestic Violence

Science.gov (United States)

Ide, Kanako

2014-01-01

This article is an attempt to develop a theory of peace education through an examination of the Fukushima Daiichi nuclear disaster. It examines why Japan did not avoid this terrible nuclear disaster. This is an educational issue, because one of the major impacts of Fukushima's catastrophe is that it indicates the failure of peace education. In…

IAEA Coordinates International Mission on Remediation of Areas Off-site Fukushima Daiichi NPP

International Nuclear Information System (INIS)

2011-01-01

Full text: The International Atomic Energy Agency (IAEA) will dispatch an international expert mission to Japan to assist the country in its planning to remediate the areas off-site from the Fukushima Daiichi Nuclear Power Plant. Following a request by the Government of Japan, the mission, comprising 12 international and IAEA experts from several countries, will visit Japan between 7 and 15 October 2011 under the leadership of Mr. Juan Carlos Lentijo, General Director for Radiation Protection at Spain's nuclear regulatory authority. The team will go to several locations in the Fukushima Prefecture and conduct meetings in Tokyo with Japanese officials to: Provide assistance to Japan in its plans to manage remediation efforts; Review the country's remediation strategies, plans and work; and Share its findings with the international community. The IAEA mission will provide an opportunity for the international experts to exchange views with the Japanese authorities involved in the decontamination effort and other interested parties. It will also provide an opportunity for the IAEA to take stock of lessons learned from this important decontamination initiative. At the end of the mission a preliminary summary report will be provided to the Government of Japan and be made publically available. The team is also planning to hold a press briefing at the end of the mission. The final report of the mission will be presented to the Government in the month following the conclusion of the mission. Background The accident at Fukushima Daiichi Nuclear Power Plant has led to the radiological contamination of large areas. The Government of Japan has been formulating a strategy and plans to implement countermeasures to remediate these areas. The IAEA organized an International Fact Finding Expert Mission Of The Fukushima Daiichi Nuclear Power Plant Accident Following The Great East Japan Earthquake And Tsunami, which was held between 24 May and 2 June 2011. The current mission is a

Development of prediction models for radioactive caesium distribution within the 80-km radius of the Fukushima Daiichi nuclear power plant

International Nuclear Information System (INIS)

Kinase, Sakae; Sato, Satoshi; Saito, Kimiaki; Takahashi, Tomoyuki; Sakamoto, Ryuichi

2014-01-01

Preliminary prediction models have been studied for the radioactive caesium distribution within the 80-km radius of the Fukushima Daiichi nuclear power plant. The models were represented by exponential functions using ecological half-life of radioactive caesium in the environment. The ecological half-lives were derived from the changes in ambient dose equivalent rates through vehicle-borne surveys. It was found that the ecological half-lives of radioactive caesium were not constant within the 80-km radius of the Fukushima Daiichi nuclear power plant. The ecological half-life of radioactive caesium in forest areas was found to be much larger than that in urban and water areas. (authors)

MDEP Common Position CP-STC-02. Common Position Addressing Fukushima Daiichi Nuclear Power Accident

International Nuclear Information System (INIS)

2016-09-01

Following the nuclear accident in Japan as a consequence of the earthquake and tsunami, the MDEP Members provide the following information, based on initial information available, to ensure adequate safety of new reactor design activities being undertaken pursuant to the MDEP program of work. Due to the extensive nature of the magnitude and duration of the Fukushima Daiichi NPP accident, it is important to consider lessons learnt at an early stage of the design. In this context, the extensive work done by the IAEA, the International Atomic Energy Agency, is also acknowledged. Vendors, licensees and applicants involved in New Design activities should examine the implications of the Fukushima Daiichi NPP accident and identify relevant issues to be taken into account to strengthen defense in depth. Those lessons learnt should include, but not be limited to, plans to assess the following: - Provisions taken in the design basis concerning flooding, earthquake, other extreme natural phenomena and combinations of external event hazards appropriate to each country, - The robustness of the plant to maintain its safety functions beyond the design basis hazards, - The capability of the plant to withstand extended loss of all electrical power supplies as well as prolonged loss of ultimate heat sink and other essential supplies, and - The capability of the plant to cope with such extreme situations, including provisions to manage severe accidents (such as combustible gas management). In assessing these areas, the effect of multiple units and nuclear fuel storages should be considered. The MDEP regulators will strive to harmonize approaches to incorporate lessons learnt in their ongoing national safety reviews of new reactors. Based on the design-specific common positions, this paper identifies the approaches to address potential safety improvements for several designs as related to lessons learned from the Fukushima Daiichi NPP accident or related issues. Designs being

MDEP AP1000WG Design-Specific Common Position CP-AP1000WG-02. Common position addressing Fukushima Daiichi NPP accident-related issues

International Nuclear Information System (INIS)

2016-09-01

A severe accident involving several units took place in Japan at Fukushima Daiichi nuclear power plant (NPP) in March 2011. The immediate cause of the accident was an earthquake followed by a tsunami coupled with inadequate provisions against the consequences of such events in the design. Opportunities to improve protection against a realistic design basis tsunami had not been taken. As a consequence of the tsunami, safety equipment and the related safety functions were lost at the plant, leading to core damage in three units and subsequently to large radioactive release. Several studies have already been performed to better understand the accident progression and detailed technical studies are still in progress in Japan and elsewhere. In the meantime, on-going studies on the behaviour of nuclear power plants in very severe situations, similar to Fukushima Daiichi, seek to identify potential vulnerabilities in plant design and operation; to suggest reasonably practicable upgrades; or to recommend enhanced regulatory requirements and guidance to address such situations. Likewise, agencies around the world that are responsible for regulating the design, construction and operation of AP1000 R plants are engaged in similar activities. The MDEP AP1000 R Working Group (AP1000 WG) members consist of members from Canada, China, the United Kingdom and the United States. Since the regulatory review of their AP1000 R applications have not been completed by all of these Countries yet, this paper identifies common preliminary approaches to address potential safety improvements for AP1000 R plants as related to lessons learned from the Fukushima Daiichi accident or Fukushima Daiichi-related issues. In seeking common position, regulators will provide input to this paper to reflect their safety conclusions regarding the AP1000 R design and how the design could be enhanced to address Fukushima Daiichi issues. The common preliminary approaches are organized into five sections

Decommissioning and environmental remediation scenario development for Fukushima Daiichi

Energy Technology Data Exchange (ETDEWEB)

Kawamura, Hideki [mcm japan, Tokyo (Japan); Yashio, Shoko [Obayashi Corporation, Tokyo (Japan); McKinley, Ian G. [McKinley Consulting, Frick (Switzerland)

2017-07-15

Although the general approach to reactor decommissioning is well established, there is no direct precedent for managing the 6 units of the Fukushima Daiichi nuclear power plant. Apart from damaged reactors, challenges include extensive contamination of the entire reactor site and a huge tank farm currently storing contaminated cooling water. In order to move forward with planning decommissioning, it is important to decide on the desired end state of the site and understand the impact on such a decision on the costs, hazards and environmental impact of the project. A decommissioning roadmap and reference dismantling concept provide a basis for short-term planning, but the potential for technological optimisation should be carefully considered.

Distribution of dose rates due to fallout from the Fukushima Daiichi reactor accident

International Nuclear Information System (INIS)

Minato, Susumu

2011-01-01

A number of dose rate data taken after the Fukushima Daiichi reactor accident occurred have been collected through official websites of prefectural governments. Subtracting natural background dose rates from these data, contributions due to fallout alone were evaluated. A train-borne survey was carried out to verify the accuracy of the contour map. The dose rate variation pattern obtained by the survey coincided fairly well with that of the map. (author)

Investigation and evaluation for environmental impact at Fukushima Daiichi NPP accident

International Nuclear Information System (INIS)

2012-01-01

In 2012, JNES investigated the weather data and the environmental monitoring data and constructed the method to specify contribution of the environmental impact from each plant based on the dose analysis result at Unit 1-3 of Fukushima Daiichi NPP accident. JNES calculated the dose rate in an accident early stage based on analysis of a monitoring data. Moreover, JNES evaluated the dose by additional release of the radioactive material in case of assuming the loss of coolant injection to a nuclear reactor by the request of NISA. (author)

A Remote-operated System to Map Radiation Dose in the Fukushima Daiichi Primary Containment Vessel

Science.gov (United States)

Nancekievill, M.; Jones, A. R.; Joyce, M. J.; Lennox, B.; Watson, S.; Katakura, J.; Okumura, K.; Kamada, S.; Katoh, M.; Nishimura, K.

2018-01-01

This paper describes the development of a submersible system based on a remote-operated vehicle coupled with radiation detectors to map the interior of the reactors at the Fukushima Daiichi nuclear power station. It has the aim oflocating fuel debris. The AVEXIS submersible vehicle used in this study has been designed as a low-cost, potentially disposable, inspection platform that is the smallest of its class and is capable of being deployed through a 150 mm diameter access pipe. To map the gamma-ray environment, a cerium bromide scintillator detector with a small form factor has been incorporated into the AVEXIS to identify radioactive isotopes via gamma-ray spectroscopy. This provides the combined system with the potential to map gamma-ray spectra and particle locations throughout submerged, contaminated facilities, such as Units 1, 2 and 3 of the Fukushima Daiichi nuclear power plant. The hypothesis of this research is to determine the sensitivity of the combined system in a submerged environment that replicates the combination of gamma radiation and water submersion but at lower dose rates.

FUKUSHIMA DAI-ICHI ACCIDENT: LESSONS LEARNED AND FUTURE ACTIONS FROM THE RISK PERSPECTIVES

Directory of Open Access Journals (Sweden)

JOON-EON YANG

2014-02-01

Full Text Available The Fukushima Dai-Ichi accident in 2011 has affected various aspects of the nuclear society worldwide. The accident revealed some problems in the conventional approaches used to ensure the safety of nuclear installations. To prevent such disastrous accidents in the future, we have to learn from them and improve the conventional approaches in a more systematic manner. In this paper, we will cover three issues. The first is to identify the key issues that affected the progress of the Fukushima Dai-Ichi accident greatly. We examine the accident from a defense-in-depth point of view to identify such issues. The second is to develop a more systematic approach to enhance the safety of nuclear installations. We reexamine nuclear safety from a risk point of view. We use the concepts of residual and unknown risks in classifying the risk space. All possible accident scenarios types are reviewed to clarify the characteristics of the identified issues. An approach is proposed to improve our conventional approaches used to ensure nuclear safety including the design of safety features and the safety assessments from a risk point of view. Finally, we address some issues to be improved in the conventional risk assessment and management framework and/or practices to enhance nuclear safety.

Fukushima Dai-Ichi accident: Lessons Learned and Future Actions from the Risk Perspectives

Energy Technology Data Exchange (ETDEWEB)

Yang, Jooneon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-02-15

The Fukushima Dai-Ichi accident in 2011 has affected various aspects of the nuclear society worldwide. The accident revealed some problems in the conventional approaches used to ensure the safety of nuclear installations. To prevent such disastrous accidents in the future, we have to learn from them and improve the conventional approaches in a more systematic manner. In this paper, we will cover three issues. The first is to identify the key issues that affected the progress of the Fukushima Dai-Ichi accident greatly. We examine the accident from a defense-in-depth point of view to identify such issues. The second is to develop a more systematic approach to enhance the safety of nuclear installations. We reexamine nuclear safety from a risk point of view. We use the concepts of residual and unknown risks in classifying the risk space. All possible accident scenarios types are reviewed to clarify the characteristics of the identified issues. An approach is proposed to improve our conventional approaches used to ensure nuclear safety including the design of safety features and the safety assessments from a risk point of view. Finally, we address some issues to be improved in the conventional risk assessment and management framework and/or practices to enhance nuclear safety.

Fukushima Daiichi - delivery of contaminated water into the Pacific ocean and possible consequences for the marine ecosystem

International Nuclear Information System (INIS)

Nies, Hartmut

2015-01-01

The nuclear power plant Fukushima Daiichi is sited at the coast of the Japanese island Honshu. Most of the cooling water for the three destroyed reactors units 1-3 and the nuclear fuel in the spent fuel pool of unit-4 were uncontrolled delivered into the groundwater and the Pacific Ocean. As a consequence high concentrations of I-131, Cs-134 and Cs-137 in the coastal waters have to be assumed. The contribution analyzed the possible consequences for the marine ecosystem. A drift time of 5 to 7 years toward the coast of North America is expected. The planning of the marine monitoring program MEXT is described. Radiation measurements in the coastal water up to 200 km distance from Daiichi were performed. The highest radionuclide concentrations of Cs-137 and Cs-134 were found in the fine grained sediments. No increased radioactivity in seafood is expected.

Effect of evacuation on liver function after the Fukushima Daiichi Nuclear Power Plant accident: The Fukushima Health Management Survey.

Science.gov (United States)

Takahashi, Atsushi; Ohira, Tetsuya; Hosoya, Mitsuaki; Yasumura, Seiji; Nagai, Masato; Ohira, Hiromasa; Hashimoto, Shigeatsu; Satoh, Hiroaki; Sakai, Akira; Ohtsuru, Akira; Kawasaki, Yukihiko; Suzuki, Hitoshi; Kobashi, Gen; Ozasa, Kotaro; Yamashita, Shunichi; Kamiya, Kenji; Abe, Masafumi

2017-04-01

The Great East Japan Earthquake and subsequent Fukushima Daiichi Nuclear Power Plant accident caused residents to switch from their normal lives to lives focused on evacuation. We evaluated liver function before and after this disaster to elucidate the effects of evacuation on liver function. This study was a longitudinal survey of 26,006 Japanese men and women living near the Fukushima Daiichi Nuclear Power Plant. This study was undertaken using data from annual health checkups conducted for persons aged 40-90 years between 2008 and 2010. Follow-up examinations were conducted from June 2011 to the end of March 2013, with a mean follow up of 1.6 years. Changes in liver function before and after the disaster were compared among evacuees and non-evacuees. We also assessed groups according to alcohol drinking status. The prevalence of liver dysfunction significantly increased in all participants from 16.4% before to 19.2% after the disaster. The incidence of liver dysfunction was significantly higher in evacuees than in non-evacuees. Multivariate logistic regression analysis showed that evacuation was significantly associated with liver dysfunction among residents. This is the first study to show that evacuation due to the Fukushima Daiichi nuclear power plant disaster was associated with an increase in liver dysfunction. Copyright © 2016 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

Safety insights from forensics evaluations at Daiichi

Directory of Open Access Journals (Sweden)

J. Rempe

2017-01-01

Information obtained from Daiichi is required to inform Decontamination and Decommissioning activities, improving the ability of the Tokyo Electric Power Company (TEPCO to characterize potential hazards and to ensure the safety of workers involved with cleanup activities. This paper reports initial results from the US Forensics Effort to utilize examination information obtained by TEPCO to enhance the safety of existing and future nuclear power plant designs. In this paper, three examples are presented in which examination information, such as visual images, dose surveys, sample evaluations, and muon tomography examinations, along with data from plant instrumentation, are used to obtain significant safety insights in the areas of component performance, fission product release and transport, debris end-state location, and combustible gas generation and transport. In addition to reducing uncertainties related to severe accident modeling progression, these insights confirm actions, such as the importance of water addition and containment venting, that are emphasized in updated guidance for severe accident prevention, mitigation, and emergency planning.

SFR Safety Consideration in Light of Fukushima Dai-ichi Accident

International Nuclear Information System (INIS)

Yamaguchi, Akira

2013-01-01

SFR Considerations: Fukushima Dai-ichi Accident: • Combined LORL and LOHS type initiated from SBO; • High pressure water-steam cooling system: – Depressurization - Not needed; – Ultimate heat sink - Robust (NC to atmosphere); – Continuous injection - Not needed (large sensible heat capacity). • Severe accident management: – RPV failure resulted in depressurization - Elevated temperature; – Heat sink to atmosphere - Freeing risk, sodium fire risk; – Mobile power supply - External resource may not be needed; – Seawater injection with fire engines - Sodium injection not needed; • Containment performance and accessibility: – Containment - Large containment volume and low pressure system; – Explosives - Sodium fire and hydrogen explosion

Partisan amplification of risk: American perceptions of nuclear energy risk in the wake of the Fukushima Daiichi disaster

International Nuclear Information System (INIS)

Yeo, Sara K.; Cacciatore, Michael A.; Brossard, Dominique; Scheufele, Dietram A.; Runge, Kristin; Su, Leona Y.; Kim, Jiyoun; Xenos, Michael; Corley, Elizabeth A.

2014-01-01

Aim: This study examines risk perceptions toward nuclear power before and after the Fukushima Daiichi disaster using nationally representative survey samples of American adults. Scope: On March 11, 2011, a magnitude 8.4 earthquake, the largest in the nation's history, occurred off the coast of Japan. The earthquake produced a devastating tsunami that flooded areas of the Fukushima Daiichi nuclear plant and resulted in a loss of power to the plant's cooling system. In the weeks that followed, the world watched as Japanese and international nuclear power safety experts scrambled to contain the damage and prevent a full meltdown. Although the Fukushima Daiichi disaster was heavily covered in media, there is little empirical research on how this coverage impacted audience risk perceptions. Our analysis goes beyond examining aggregate risk perceptions, instead focusing on how specific sub-populations responded to the disaster. Conclusion: We found that ideological groups responded differently to the events in Japan. In particular, risk perceptions among conservatives decreased following the incident. Moreover, we found that media use exacerbated these effects. We discuss possible explanations for these findings. - Highlights: • We explored American risk perceptions of nuclear energy pre- and post-Fukushima. • Impacts of the disaster endured, likely due to relatively high media coverage. • Conservatives who paid more attention to media perceived less risk post-Fukushima. • Media coverage can serve to polarize opinions instead of mainstreaming them

Atmospheric dispersion modeling: Challenges of the Fukushima Daiichi response

Energy Technology Data Exchange (ETDEWEB)

Sugiyama, Gayle [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nasstrom, John [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pobanz, Brenda [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Foster, Kevin [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Simpson, Matthew [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Vogt, Phil [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Aluzzi, Fernando [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Homann, Steve [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2012-05-01

In this research, the U.S. Department of Energy’s (DOE) National Atmospheric Release Advisory Center (NARAC) provided a wide range of predictions and analyses as part of the response to the Fukushima Daiichi Nuclear Power Plant accident including: daily Japanese weather forecasts and atmospheric transport predictions to inform planning for field monitoring operations and to provide U.S. government agencies with ongoing situational awareness of meteorological conditions; estimates of possible dose in Japan based on hypothetical U.S. Nuclear Regulatory Commission scenarios of potential radionuclide releases to support protective action planning for U.S. citizens; predictions of possible plume arrival times and dose levels at U.S. locations; and source estimation and plume model refinement based on atmospheric dispersion modeling and available monitoring data.

Evaluation of seismic design by students made after Fukushima Dai-ichi accident

International Nuclear Information System (INIS)

Sugiyama, Ken-ichiro

2012-01-01

The sense of anxiety for safety of nuclear power plants among people in Japan has not disappeared after Fukushima Dai-ichi accident because of a typical country with frequent earthquakes. The provision of information for seismic design in nuclear power plants prepared for easier comprehension is always required in any kind of study meetings for the social acceptance of nuclear power plants. In the present paper, the effect of the provision of information made an attempt for students in Hokkaido University is reported. (author)

Monitoring Cs-134 and 137 released by Fukushima Dai-ichi Nuclear Power Plant accident in ground, soil, and stream waters

Science.gov (United States)

Tsujimura, Maki; Onda, Yuichi; Hada, Manami; Ishwar, Pun; Abe, Yutaka

2013-04-01

Due to Fukushima Dai-ichi Nuclear power plant accident occurred in March 2011, large amount of radionuclides was released into the atmosphere and was fallen onto ground by rainfall. Few researches have monitored radioactive cesium dynamics in whole hydrological cycle system such as groundwater, soil water, spring water and stream water. Thus, the purpose of this study is to monitor concentration of radioactive cesium in those waters in time series in the headwaters. We have performed an intensive monitoring at three small mountainous catchments in Yamakiya district, Kawamata town, Fukushima prefecture, locating 35 km northwest from Fukushima Dai-ichi Nuclear Power Plant since June 2011, also we consider the movement of radioactive cesium and its relation with the hydrological cycle.

Demonstration of laser processing technique combined with water jet technique for retrieval of fuel debris at Fukushima Daiichi Nuclear Power Station

International Nuclear Information System (INIS)

Hanari, Toshihide; Takebe, Toshihiko; Yamada, Tomonori; Daido, Hiroyuki; Ishizuka, Ippei; Ohmori, Shinya; Kurosawa, Koichi; Sasaki, Go; Nakada, Masahiro; Sakai, Hideaki

2017-01-01

In decommissioning of Fukushima Daiichi Nuclear Power Station, a retrieval process of fuel debris in the Primary Containment Vessel by a remote operation is one of the key issues. In this process, prevention of spreading radioactive materials is one of the important considerations. Furthermore, an applicable technique to the process requires keeping of reasonable processing-efficiency. We propose to use the combined technique including a laser light and a water jet as a retrieval technique of the fuel debris. The laser processing technique combined with a repetitive pulsed water jet could perform an efficient retrieval processing. Our experimental result encourages us to promote further development of the technique towards a real application at Fukushima Daiichi Nuclear Power Station. (author)

The Fukushima Daiichi Accident. Technical Volume 1/5. Description and Context of the Accident. Annexes

International Nuclear Information System (INIS)

2015-08-01

The Fukushima Daiichi Accident consists of a Report by the IAEA Director General and five technical volumes. It is the result of an extensive international collaborative effort involving five working groups with about 180 experts from 42 Member States with and without nuclear power programmes and several international bodies. It provides a description of the accident and its causes, evolution and consequences, based on the evaluation of data and information from a large number of sources available at the time of writing. The Fukushima Daiichi Accident will be of use to national authorities, international organizations, nuclear regulatory bodies, nuclear power plant operating organizations, designers of nuclear facilities and other experts in matters relating to nuclear power, as well as the wider public. The set contains six printed parts and five supplementary CD-ROMs. Contents: Report by the Director General; Technical Volume 1/5, Description and Context of the Accident; Technical Volume 2/5, Safety Assessment; Technical Volume 3/5, Emergency Preparedness and Response; Technical Volume 4/5, Radiological Consequences; Technical Volume 5/5, Post-accident Recovery; Annexes. The Report by the Director General is available separately in Arabic, Chinese, English, French, Russian, Spanish and Japanese

Removal of Radionuclides from Waste Water at Fukushima Daiichi Nuclear Power Plant: Desalination and Adsorption Methods - 13126

Energy Technology Data Exchange (ETDEWEB)

Kani, Yuko; Kamosida, Mamoru; Watanabe, Daisuke [Hitachi Research Laboratory, Hitachi, Ltd., 7-2-1 Omika-cho, Hitachi, Ibaraki, 319-1221 (Japan); Asano, Takashi; Tamata, Shin [Hitachi Works, Hitachi-GE Nuclear Energy, Ltd. (Japan)

2013-07-01

Waste water containing high levels of radionuclides due to the Fukushima Daiichi Nuclear Power Plant accident, has been treated by the adsorption removal and reverse-osmosis (RO) desalination to allow water re-use for cooling the reactors. Radionuclides in the waste water are collected in the adsorbent medium and the RO concentrate (RO brine) in the water treatment system currently operated at the Fukushima Daiichi site. In this paper, we have studied the behavior of radionuclides in the presently applied RO desalination system and the removal of radionuclides in possible additional adsorption systems for the Fukushima Daiichi waste water treatment. Regarding the RO desalination system, decontamination factors (DFs) of the elements present in the waste water were obtained by lab-scale testing using an RO unit and simulated waste water with non-radioactive elements. The results of the lab-scale testing using representative elements showed that the DF for each element depended on its hydrated ionic radius: the larger the hydrated ionic radius of the element, the higher its DF is. Thus, the DF of each element in the waste water could be estimated based on its hydrated ionic radius. For the adsorption system to remove radionuclides more effectively, we studied adsorption behavior of typical elements, such as radioactive cesium and strontium, by various kinds of adsorbents using batch and column testing. We used batch testing to measure distribution coefficients (K{sub d}s) for cesium and strontium onto adsorbents under different brine concentrations that simulated waste water conditions at the Fukushima Daiichi site. For cesium adsorbents, K{sub d}s with different dependency on the brine concentration were observed based on the mechanism of cesium adsorption. As for strontium, K{sub d}s decreased as the brine concentration increased for any adsorbents which adsorbed strontium by intercalation and by ion exchange. The adsorbent titanium oxide had higher K{sub d}s and it

Removal of Radionuclides from Waste Water at Fukushima Daiichi Nuclear Power Plant: Desalination and Adsorption Methods - 13126

International Nuclear Information System (INIS)

Kani, Yuko; Kamosida, Mamoru; Watanabe, Daisuke; Asano, Takashi; Tamata, Shin

2013-01-01

Waste water containing high levels of radionuclides due to the Fukushima Daiichi Nuclear Power Plant accident, has been treated by the adsorption removal and reverse-osmosis (RO) desalination to allow water re-use for cooling the reactors. Radionuclides in the waste water are collected in the adsorbent medium and the RO concentrate (RO brine) in the water treatment system currently operated at the Fukushima Daiichi site. In this paper, we have studied the behavior of radionuclides in the presently applied RO desalination system and the removal of radionuclides in possible additional adsorption systems for the Fukushima Daiichi waste water treatment. Regarding the RO desalination system, decontamination factors (DFs) of the elements present in the waste water were obtained by lab-scale testing using an RO unit and simulated waste water with non-radioactive elements. The results of the lab-scale testing using representative elements showed that the DF for each element depended on its hydrated ionic radius: the larger the hydrated ionic radius of the element, the higher its DF is. Thus, the DF of each element in the waste water could be estimated based on its hydrated ionic radius. For the adsorption system to remove radionuclides more effectively, we studied adsorption behavior of typical elements, such as radioactive cesium and strontium, by various kinds of adsorbents using batch and column testing. We used batch testing to measure distribution coefficients (K d s) for cesium and strontium onto adsorbents under different brine concentrations that simulated waste water conditions at the Fukushima Daiichi site. For cesium adsorbents, K d s with different dependency on the brine concentration were observed based on the mechanism of cesium adsorption. As for strontium, K d s decreased as the brine concentration increased for any adsorbents which adsorbed strontium by intercalation and by ion exchange. The adsorbent titanium oxide had higher K d s and it was used for

Situation of Fukushima Dai-ichi power plant in Japan - June 1, 2011 status

International Nuclear Information System (INIS)

2011-01-01

This situation note is established according to the information gained on June 1, 2011 by the crisis centre of the French institute of radiation protection and nuclear safety (IRSN). The situation of the cores of reactors 1, 2 and 3 of the Fukushima I site (Dai-ichi) and of the different spent fuel pools is briefly presented as well as the actions in progress for the control of environmental radioactive releases and for the progressive recovery of the facilities control. (J.S.)

Situation of Fukushima Dai-ichi power plant in Japan - May 25, 2011 status

International Nuclear Information System (INIS)

2011-01-01

This situation note is established according to the information gained on May 25, 2011 by the crisis centre of the French institute of radiation protection and nuclear safety (IRSN). The situation of the cores of reactors 1, 2 and 3 of the Fukushima I site (Dai-ichi) and of the different spent fuel pools is briefly presented as well as the actions in progress for the control of environmental radioactive releases and for the progressive recovery of the facilities control. (J.S.)

Situation of Fukushima Dai-ichi power plant in Japan - May 25, 2011 status; Situation de la centrale nucleaire de Fukushima Dai-ichi au Japon - Point de situation du 25 mai 2011

Energy Technology Data Exchange (ETDEWEB)

NONE

2011-07-01

This situation note is established according to the information gained on May 25, 2011 by the crisis centre of the French institute of radiation protection and nuclear safety (IRSN). The situation of the cores of reactors 1, 2 and 3 of the Fukushima I site (Dai-ichi) and of the different spent fuel pools is briefly presented as well as the actions in progress for the control of environmental radioactive releases and for the progressive recovery of the facilities control. (J.S.)

Hydrogen combustion in a flat semi-confined layer with respect to the Fukushima Daiichi accident

Energy Technology Data Exchange (ETDEWEB)

Kuznetsov, Mike, E-mail: kuznetsov@kit.edu [Karlsruhe Institute of Technology, 76131 Karlsruhe (Germany); Yanez, Jorge [Karlsruhe Institute of Technology, 76131 Karlsruhe (Germany); Grune, Joachim; Friedrich, Andreas [Pro-Science GmbH, 76275 Ettlingen (Germany); Jordan, Thomas [Karlsruhe Institute of Technology, 76131 Karlsruhe (Germany)

2015-05-15

Graphical abstract: - Highlights: • Critical conditions for flame propagation regimes in a layer geometry are analyzed. • Numerical simulation of hydrogen explosion reproduces real strength of shock waves. • From 80 to 200 kg of hydrogen were exploded during Fukushima (Unit I) accident. • A sonic deflagration with TNT equivalent of 800 kg was the most probable regime. - Abstract: Hydrogen accumulations at the top of a containment or reactor building may occur due to the interaction of molten corium and water followed by a severe accident of a nuclear reactor (TMI, Chernobyl, Fukushima Daiichi). The hydrogen that is released from the reactor accumulates usually as a stratified semi-confined layer of hydrogen–air mixture. A series of large scale experiments on hydrogen combustion and explosion in a semi-confined layer of uniform and non-uniform hydrogen–air mixtures in the presence of obstructions or without them was performed at the Karlsruhe Institute of Technology (KIT). Different flame propagation regimes from slow subsonic to relatively fast sonic flames and then to detonations were experimentally investigated in different geometries and then simulated with COM3D code with respect to evaluate the amount of hydrogen that was involved in the Fukushima Daiichi Accident (FDA). The experiments were performed in a horizontal semi-confined layer with the dimensions 9 × 3 × 0.6 m with/without obstacles opened from below. The hydrogen concentration in the mixtures with air was varied in the range of 10–34 vol.% without or with a gradient of 20–60 vol.%H{sub 2}/m. Effects of hydrogen concentration gradient, layer thickness, obstruction geometry, average and maximum hydrogen concentration on the flame propagation regimes were investigated with respect to evaluate the maximum pressure loads on internal structures. Blast wave strength and dynamics of propagation after the explosion of the hydrogen–air mixture layer were numerically simulated to reproduce

Abbreviations [Annex to The Fukushima Daiichi Accident, Technical Volume 5/5

International Nuclear Information System (INIS)

2015-01-01

This annex is a list of abbreviations used in the publication The Fukushima Daiichi Accident, Technical Volume 5/5. The list includes the abbreviations for: • General Safety Requirements; • International Commission on Radiological Protection; • Intensive Contamination Survey Area; • International Experts Meeting; • Ministry of Education, Culture, Sports, Science and Technology; • Ministry of the Environment; • Nuclear Damage Compensation and Decommissioning Facilitation Corporation; • Nuclear Emergency Response Headquarters; • nuclear power plant; • Nuclear Safety Commission; • OECD Nuclear Energy Agency; • Special Decontamination Area; • Specific Safety Requirements; • technical cooperation; • Three Mile Island; • United Nations Scientific Committee on the Effects of Atomic Radiation

In-core monitor housing replacement at Fukushima Daiichi Unit No.4

International Nuclear Information System (INIS)

Arai, Tomoyuki

1999-01-01

The in-core monitor (ICM) housing replacement of a Boiling Water Reactor (BWR) has been completed at Fukushima-Daiichi Unit No. 4 (1F4) of the Tokyo Electric Power Company (TEPCO) in Japan. Since cracking of the inside surface of an ICM housing was found in this unit, the ICM housing was replaced with one made of low-carbon stainless steel (SS) to improve Intergranular Stress Corrosion Cracking (IGSCC) resistance. This project is the first application of the replacement procedure for the ICM housing and employs various advanced technologies. The outline of the ICM housing replacement project and applied technologies are discussed in this paper. (author)

Telephone counseling for the public after the Fukushima Daiichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Horiguchi, T.; Kojima, K.; Itoh, T.

2011-01-01

After the Fukushima Daiichi Nuclear Power Plant accident, Kinki University Atomic Energy Research Institute provided telephone counseling services in order to respond the public's growing concerns about radiation and nuclear energy. Three telephone lines were newly installed for the counseling and the number of consultation marked 705 between March 24 and April 2. In this report, by summarizing the contents of the counseling, we will show what the public concerned about shortly after the accident and report how we responded to the concerns. (author)

Additional examination on station blackout caused by tsunami in Fukushima Daiichi NPS

International Nuclear Information System (INIS)

Yamauchi, Daisuke; Date, Kenji; Mizokami, Masato; Honda, Takeshi; Nozaki, Kenichiro; Mizokami, Shinya; Endo, Ryohei

2017-01-01

This study is additional examination to verify in a more reliable way the assessment that the emergency AC power supply was lost due to tsunami at Fukushima Daiichi Nuclear Power Station. It confirmed the relationship between the path length of tsunami intrusion reaching each power supply facility and the function loss time. As a result of examination, it was confirmed that as the path length of the tsunami intrusion reaching each power supply facility was longer, the function loss time tended to be later. So, conventional assessment that the function of each power supply facility was lost due to the run-up and flooding of tsunami has become more probable. For facilities, where the overall trend and the loss time of function were divergent, it was found that there were scenarios that could reasonably be explained. Based on the fact that the Fukushima Daiichi Nuclear Power Station lost power due to the tsunami, Kashiwazaki-Kariwa Nuclear Power Station carries out various safety measures. First of all, as the measures to prevent accidents caused by tsunami, the following have been applied: (1) prevention of the inflow of tsunamis into premises, (2) water prevention of the areas installed with important equipment, (3) securement of seawater at the time of backwashing, (4) storage of portable equipment at high ground, (5) installation of tsunami surveillance cameras. To prepare for the loss of power supply, this station implemented power supply facilities such as generator cars and distribution boards, as well as the placement of power supply cars at high ground. (A.O.)

Monitoring of Radionuclide Contamination in Food Samples in Malaysia due to Daiichi Reactor Accident in Fukushima, Japan

International Nuclear Information System (INIS)

Nurrul Assyikeen Mohd Jaffary; Abdul Kadir Ishak; Wo, Y.M.

2011-01-01

On March 11, 2011, a serious accident occurred in Daiichi nuclear reactor plant, Fukushima, Japan which caused radioactive materials been released into the atmosphere in the form of aerosols and dust particles. Sea water around the plant was also found contaminated with high radioactivity readings. These radioactive materials could be transported by the winds and ocean current across international borders and cannot be controlled by human. Besides a continuous monitoring activity of radionuclide content in the air and sea water that need to be conducted by the authorities, Malaysia should also control the entry of radionuclide through contaminated food ingestion by human. Radionuclide I-131, Cs-134 and Cs-137 were used as a counter-measure of pollution levels and counted with gamma spectrometry using standard analysis method suggested by AOAC International. In this paper, details description of the role of Radiochemical and Environment Group, Nuclear Malaysia who's responsible in analyzing the radioactivity in the food samples due to Fukushima Daiichi, Japan accident was included. Also discussed are the radioactivity limit adopted and analysis results from this monitoring. (author)

Fukushima Daiichi Unit 1 Accident Progression Uncertainty Analysis and Implications for Decommissioning of Fukushima Reactors - Volume I.

Energy Technology Data Exchange (ETDEWEB)

Gauntt, Randall O. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mattie, Patrick D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2016-01-01

Sandia National Laboratories (SNL) has conducted an uncertainty analysis (UA) on the Fukushima Daiichi unit (1F1) accident progression with the MELCOR code. The model used was developed for a previous accident reconstruction investigation jointly sponsored by the US Department of Energy (DOE) and Nuclear Regulatory Commission (NRC). That study focused on reconstructing the accident progressions, as postulated by the limited plant data. This work was focused evaluation of uncertainty in core damage progression behavior and its effect on key figures-of-merit (e.g., hydrogen production, reactor damage state, fraction of intact fuel, vessel lower head failure). The primary intent of this study was to characterize the range of predicted damage states in the 1F1 reactor considering state of knowledge uncertainties associated with MELCOR modeling of core damage progression and to generate information that may be useful in informing the decommissioning activities that will be employed to defuel the damaged reactors at the Fukushima Daiichi Nuclear Power Plant. Additionally, core damage progression variability inherent in MELCOR modeling numerics is investigated.

Accident analysis of Fukushima Daiichi Nuclear Power Station unit 1

International Nuclear Information System (INIS)

Kobayashi, Masahide; Narabayashi, Tadashi; Tsuji, Masashi; Chiba, Go; Nagata, Yasunori; Shimoe, Tomohiro

2015-01-01

As a result of the Great East Japan Earthquake that occurred on 11 March 2011, all AC and DC power at the Fukushima Daiichi NPP units 1 to 3 were lost soon after the tsunami. The core cooling function was lost, and the cores of units 1 to 3 were damaged. The purpose of this work is to clarify the progress of the accident in unit 1, which was damaged the earliest among the 3 units. Therefore, an original severe accident analysis code was developed, and the progress of the accident was evaluated from the analysis results and the actual data. As a result, the leakage path from a pressure vessel was clarified, and some lessons and knowledge were gained. (author)

Fukushima-Daiichi accident. News bulletin no. 2 from April 8

International Nuclear Information System (INIS)

2011-01-01

This news bulletin has been prepared by the French institute of radiation protection and nuclear safety (IRSN) for the information of French residents in Japan. It presents, first, the situation at the date of the bulletin of the reactors at the power plant site, the accident management actions in progress, the radioactive contamination around the site, the evolution of radioactivity in the air of Tokyo since March 15, the meteorological forecasts, and the impact of the April 7 earthquake. Then, it gives some general recommendations to residents concerning food consumption and dwelling hygiene. Finally, some scientific information about radionuclides migration, radioactive pollution and their environmental impact are given. The geographic distribution of radioactive fallouts around the Fukushima-Daiichi site is shown. (J.S.)

Outline of the Fukushima Daiichi Accident. Lessons Learned and Safety Enhancements

Science.gov (United States)

Hirano, Masashi

2017-09-01

Abstract. On March 11, 2011, an earthquake and subsequent tsunamis off the Pacific coastline of Japan's Tohoku region caused widespread devastation in Japan. As of June 10, 2016, it is reported that a total of 15,894 people lost their lives and 2,558 people are still unaccounted for. In Fukushima Prefecture, approximately 100,000 people are still obliged to live away from their homes due to the earthquake and tsunami as well as the Fukushima Daiichi accident. On the day, the earthquake and tsunami caused severe damages to the Tokyo Electric Power Company (TEPCO)'s Fukushima Daiichi Nuclear Power Station (NPS). All the units in operation, namely Units 1 to 3, were automatically shut down on seismic reactor protection system trips but the earthquake led to the loss of all off-site electrical power supplies to that site. The subsequent tsunami inundated the site up to 4 to 5 m above its ground level and caused, in the end, the loss of core cooling function in Units 1 to 3, resulting in severe core damages and containment vessel failures in these three units. Hydrogen was released from the containment vessels, leading to explosions in the reactor buildings of Units 1, 3 and 4. Radioactive materials were released to the atmosphere and were deposited on the land and in the ocean. One of the most important lessons learned is an importance to prevent such large scale common cause failures due to extreme natural events. This leads to a conclusion that application of the defense-in-depth philosophy be enhanced because the defense-in-depth philosophy has been and continues to be an effective way to account for uncertainties associated with risks. From the human and organizational viewpoints, the final report from the Investigation Committee of the Government pointed out so-called "safety myth" that existed among nuclear operators including TEPCO as well as the government, that serious severe accidents could never occur in nuclear power plants in Japan. After the accident, the

Situation of Fukushima Dai-ichi power plant in Japan - June 1, 2011 status; Situation de la centrale nucleaire de Fukushima Dai-ichi au Japon - Point de situation du 1er juin 2011

Energy Technology Data Exchange (ETDEWEB)

NONE

2011-07-01

This situation note is established according to the information gained on June 1, 2011 by the crisis centre of the French institute of radiation protection and nuclear safety (IRSN). The situation of the cores of reactors 1, 2 and 3 of the Fukushima I site (Dai-ichi) and of the different spent fuel pools is briefly presented as well as the actions in progress for the control of environmental radioactive releases and for the progressive recovery of the facilities control. (J.S.)

WHO's public health agenda in response to the Fukushima Daiichi nuclear accident

International Nuclear Information System (INIS)

Van Deventer, Emilie; Del Rosario Perez, Maria; Carr, Zhanat; Tritscher, Angelika; Fukushima, Kazuko

2012-01-01

The World Health Organization (WHO) has responded to the 2011 East-Japan earthquake and tsunami through the three levels of its decentralised structure. It has provided public health advice regarding a number of issues relating to protective measures, potassium iodide use, as well as safety of food and drinking water, mental health, travel, tourism, and trade. WHO is currently developing an initial health risk assessment linked to a preliminary evaluation of radiation exposure around the world from the Fukushima Daiichi nuclear accident. Lessons learned from this disaster are likely to help future emergency response to multi-faceted disasters. (note)

Cooperation in the Implementation of Safeguards at Fukushima Dai-ichi Site

International Nuclear Information System (INIS)

Kumekawa, H.; Usui, A.; Sano, K.; Ishii, T.; Ninagawa, J.; Namekawa, M.; Iso, S.; Nakamura, N.; Hirato, Y.; Murajiri, M.; Hori, K.; Oyama, K.; Takagi, A.; Hirabayashi, N.

2015-01-01

The accident at Fukushima Dai-ichi Nuclear Power Station caused by the Great East Japan Earthquake and tsunami in March 2011 had a major impact on the safeguards situation at the site. JSGO, NMCC, TEPCO and JAEA are tackling the challenges posed by the accident jointly with the IAEA and in cooperation with the US Department of Energy (DOE). From the day of the earthquake, JSGO and the IAEA have shared information on decommissioning activities and discussed how to deal with this difficult issue. In May 2012, the Fukushima Task Force was established. Its objective is to develop a holistic approach to safeguards implementation measures for the site, to monitor the re-establishment of safeguards, to facilitate discussion of relevant issues, and to consider possible approaches to longer-term safeguards challenges. All the fuels in spent fuel ponds in Units 5 and 6 and Common Spent Fuel Storage have been successfully re-verified. Re-verification of fuels kept in spent fuel pond in Unit 4 is underway. A special arrangement called SNOS (Short Notice Operational Support Activities) has been introduced to confirm non-diversion of declared material at Fukushima Dai-ichi site. Based on extensive information exchange, proactive discussions on safeguards approaches are being held for near-term issues. The damaged core material in Units 1-3 will pose extreme difficulties in longer-term. A special sub-group has been established under the task force to address the issues. Although lessons learned from past nuclear accidents resulting in damage of core material have some relevance, none of them can be directly applicable for Fukushima. Thus a foresighted and creative approach is needed. Close coordination with the IAEA and support from technically competent institutions in Japan and from abroad, such as DOE, are also essential to tackle the issues. (author)

Fukushima Daiichi Nuclear Power Plant accident: facts, environmental contamination, possible biological effects, and countermeasures

OpenAIRE

Anzai, Kazunori; Ban, Nobuhiko; Ozawa, Toshihiko; Tokonami, Shinji

2011-01-01

On March 11, 2011, an earthquake led to major problems at the Fukushima Daiichi Nuclear Power Plant. A 14-m high tsunami triggered by the earthquake disabled all AC power to Units 1, 2, and 3 of the Power Plant, and carried off fuel tanks for emergency diesel generators. Despite many efforts, cooling systems did not work and hydrogen explosions damaged the facilities, releasing a large amount of radioactive material into the environment. In this review, we describe the environmental impact of...

Accident at the Fukushima Dai-ichi Nuclear Power Stations of TEPCO —Outline & lessons learned—

OpenAIRE

TANAKA, Shun-ichi

2012-01-01

The severe accident that broke out at Fukushima Dai-ichi nuclear power stations on March 11, 2011, caused seemingly infinite damage to the daily life of residents. Serious and wide-spread contamination of the environment occurred due to radioactive materials discharged from nuclear power stations (NPSs). At the same time, many issues were highlighted concerning countermeasures to severe nuclear accidents. The accident is outlined, and lessons learned are extracted with respect to the safety o...

Remediation activities wrestling with environmental pollution and radwaste generated by the Fukushima Daiichi NPP accident due to the Tohoku district-off the pacific ocean

International Nuclear Information System (INIS)

Kawanishi, Motoi; Fujitsuka, Tetsuro; Yoshihara, Koichi; Katsumi, Takeshi; Tochiyama, Osamu

2013-01-01

Based on the lectures and panel discussions 'Radioactive waste countermeasures and the role of civil engineering technology' on the occasion of 3rd year of the Great East Japan Earthquake, March 11, 2011, hosted by the Japan Society of Civil Engineers, the paper summarizes remediation activities reported during the seminar. Radioactive materials contaminated area due to the Fukushima Daiichi Nuclear Power Plant accident from the Department of Environment, endeavors for setting-up of temporary storage facilities for the decontaminated soils and solid wastes, present status of roadmap toward the decommissioning of the Fukushima Daiichi Plants from the Japanese Government and Tokyo Electric Power Co. were presented followed by expectations of civil engineers cooperation. (S. Ohno)

No mixed feelings : The post-Lisbon Common Commercial Policy in Daiichi Sankyo and Commission v. Council (Conditional Access Convention)

NARCIS (Netherlands)

Larik, J.E.

2015-01-01

Double case note on the scope of the EU's Common Commercial Policy and the future of "mixed agreements" based on the two ECJ Grand Chamber Judgements Case C-414/11, Daiichi Sankyo Co. Ltd and Sanofi-Aventis Deutschland GmbH v. DEMO Anonimos Viomichaniki kai Emporiki Etairia Farmakon, Judgment of the

Monitoring of Radionuclide Contamination in Food Samples in Malaysia due to Daiichi Reactor Accident in Fukushima, Japan

International Nuclear Information System (INIS)

Nurrul Assyikeen Mohd Jaffary; Wo, Y.M.; Abdul Kadir Ishak

2015-01-01

On March 11, 2011, a serious accident occurred in Daiichi nuclear reactor plant, Fukushima, Japan which caused radioactive materials been released into the atmosphere in the form of aerosols and dust particles. Sea water around the plant was also found contaminated with high radioactivity readings. These radioactive materials could be transported by the winds and ocean current across international borders and cannot be controlled by human. Thus, a continuous monitoring activity of radionuclide content in the air and sea water needs to be conducted by the authorities. In addition to radioactivity monitoring, Malaysia should also control the entry of contaminated food in order to prevent radionuclide ingestion by human. The radionuclide 131 I, 134 Cs and 137 Cs were used as a measure of pollution levels and counted with gamma spectrometry using standard analysis method suggested by AOAC International. In this paper, details description of the role of Radiochemical and Environment Group, Nuclear Malaysia who is responsible in analyzing the radioactivity in the food samples due to Fukushima Daiichi, Japan accident was included. The radioactivity limit adopted and analysis results from this monitoring were discussed. (author)

Damage of reactor buildings occurred at the Fukushima Daiichi accident. Focusing on sequence leading to hydrogen explosions

International Nuclear Information System (INIS)

Naito, Masanori

2011-01-01

Fukushima Daiichi accident discharged enormous radioactive materials confined inside into the environment due to hydrogen explosions occurred at reactor buildings and forced many people to live the refugee life. This article described overview of Great East Japan Earthquake, specifications of Fukushima Daiichi nuclear power plants, sequence of plant status after earthquake occurrence and computerized simulation of plant behavior of Unit 1 leading to core melt and hydrogen explosion. Simulation results with estimated and assumed conditions showed water level decreased to bottom of reactor core after 4 hrs and 15 minutes passed, core melt started after 6 hrs and 49 minutes passed, failure of core support plate after 7 hrs and 18 minutes passed and through failure of penetration at bottom of pressure vessel after 7 hrs and 25 minutes passed. Hydrogen concentration at operating floor of reactor building of Unit 1 would be 15% accumulated and the pressure would amount to about 5 bars after hydrogen explosion if reactor building did not rupture with leak-tight structure. Since reactor building was not pressure-proof structure, walls of operating floor would rupture before 5 bars attained. (T. Tanaka)

Dose estimation from food intake due to the Fukushima Daiichi nuclear power plant accident

International Nuclear Information System (INIS)

Yamaguchi, Ichiro; Terada, Hiroshi; Kunugita, Naoki; Takahashi, Kunihiko

2013-01-01

Since the Fukushima Daiichi nuclear power plant accident, concerns have arisen about the radiation safety of food raised at home and abroad. Therefore, many measures have been taken to address this. To evaluate the effectiveness of these measures, dose estimation due to food consumption has been attempted by various methods. In this paper, we show the results of dose estimation based on the monitoring data of radioactive materials in food published by the Ministry of Health, Labour and Welfare. The Radioactive Material Response Working Group in the Food Sanitation Subcommittee of the Pharmaceutical Affairs and Food Sanitation Council reported such dose estimation results on October 31, 2011 using monitoring data from immediately after the accident through September, 2011. Our results presented in this paper were the effective dose and thyroid equivalent dose integrated up to December 2012 from immediately after the accident. The estimated results of committed effective dose by age group derived from the radioiodine and radiocesium in food after the Fukushima Daiichi nuclear power plant accident showed the highest median value (0.19 mSv) in children 13-18 years of age. The highest 95% tile value, 0.33 mSv, was shown in the 1-6 years age range. These dose estimations from food can be useful for evaluation of radiation risk for individuals or populations and for radiation protection measures. It would also be helpful for the study of risk management of food in the future. (author)

Radiological protection and the Fukushima Daiichi accident. Responses of the key international organisations

Energy Technology Data Exchange (ETDEWEB)

Clement, Christopher

2017-10-01

The Fukushima Daiichi nuclear power plant accident in March 2011 shook the radiological protection world. All major organisations in the radiological protection field turned their eyes to Japan. Their actions, driven by their mandates, are reflected in their respective landmark reports on the accident. Reports of the International Commission on Radiological Protection, World Health Organisation, United Nations Scientific Committee on the Effects of Atomic Radiation, and International Atomic Energy Agency are summarised. Collaboration between key international organisations is strong, based in part on informal interactions which need to be backed up with formal relations to ensure solid long-term collaboration.

Research on vitrification technology to immobilize radioactive sludge generated from Fukushima Daiichi power plant. Enhanced glass medium

International Nuclear Information System (INIS)

Amamoto, Ippei; Kobayashi, Hidekazu; Kitamura, Naoto; Takebe, Hiromichi; Mitamura, Naoki; Tsuzuki, Tatsuya; Fukayama, Daigen; Nagano, Yuichi; Jantzen, Tatjana; Hack, Klaus

2016-01-01

The search for an enhanced glass medium to immobilize the sludge at the Fukushima Daiichi Nuclear Power Plant is our main purpose. The iron phosphate glass (IPG) is a potential candidate as we set about assessing it by means of theoretical and experimental investigation. Based on the results of this study, the IPG showed favorable characteristics as a vitrification medium for the sludge. (author)

The Scope of the Common Commercial Policy after Lisbon: The Daiichi Sankyo and Conditional Access Services Grand Chamber Judgments

NARCIS (Netherlands)

Ankersmit, L.J.

2014-01-01

This case note discusses two important recent judgments rendered by the ECJ on the scope of the Common Commercial Policy. In Daiichi Sankyo (Case C-414/11), the Court overturned its previous case law on TRIPs in light of the entry into force of the Lisbon Treaty. In Conditional Access Services (Case

Dose rate evaluation of workers on the operation floor in Fukushima-Daiichi Unit 3

Science.gov (United States)

Matsushita, Kaoru; Kurosawa, Masahiko; Shirai, Keisuke; Matsuoka, Ippei; Mukaida, Naoki

2017-09-01

At Fukushima Daiichi Nuclear Power Plant Unit 3, installation of a fuel handling machine is planned to support the removal of spent fuel. The dose rates at the workplace were calculated based on the source distribution measured using a collimator in order to confirm that the dose rates on the operation floor were within a manageable range. It was confirmed that the accuracy of the source distribution was C/M = 1.0-2.4. These dose rates were then used to plan the work on the operation floor.

Accident on the TEPCO reactors of Fukushima-Daiichi. A focus on the situation in January 2013

International Nuclear Information System (INIS)

2013-01-01

After a brief recall of the accident of the Fukushima-Daiichi nuclear power station and a brief description of the general condition of the installations after the accident, this report proposes an overview of actions performed by TEPCO to control the installations, the actions performed to control effluents and releases. It presents the action plan for the control's recovery of installations, and briefly evokes the situation for other electronuclear reactors in Japan

The Fukushima Daiichi Nuclear Power Plant accident and school bullying of affected children and adolescents: the need for continuous radiation education.

Science.gov (United States)

Sawano, Toyoaki; Nishikawa, Yoshitaka; Ozaki, Akihiko; Leppold, Claire; Tsubokura, Masaharu

2018-04-09

The health threats of radiation-release incidents are diverse and long term. In addition to direct radiation effects, it is imperative to manage the indirect effects of radiation such as stigma, prejudice and broader mental health impacts. Six years after the Fukushima Daiichi Nuclear Power Plant accident of March 2011, bullying caused by stigma and prejudice toward evacuees, including children, has become a social problem in Japan. This phenomenon may be associated with the fact that knowledge about radiation has still not reached the general public, and to a potential lack of motivation among Japanese citizens to learn about radiation and bullying. Continuous and sustained education regarding radiation is warranted in order to enhance the general knowledge level about the effects of radiation in Japan after the Fukushima Daiichi Nuclear Power Plant accident, and this education will become an important reference for education after future nuclear disasters.

Development of source term PIRT of Fukushima Daiichi NPPs accident

International Nuclear Information System (INIS)

Suehiro, S.; Okamoto, K.

2017-01-01

The severe accident evaluation committee of AESJ (Atomic Energy Society of Japan) developed the thermal hydraulic PIRT (Phenomena Identification and Ranking Table) and the source term PIRT based on findings during the Fukushima Daiichi NPPs accident. These PIRTs aimed to explore the debris distribution and the current condition in the NPPs with high accuracy and to extract higher priority from the aspect of the sophistication of the analytical technology to predict the severe accident phenomena by the code. The source term PIRT was divided into 3 phases for the time domain and 9 categories for the spatial domain. The 68 phenomena were extracted and the importance from viewpoint of the source term was ranked through brainstorming and discussion. This paper describes the developed source term PIRT list and summarized the high ranked phenomena in each phase. (author)

Multi-Phased, Post-Accident Support of the Fukushima Dai-Ichi Nuclear Power Plant - 12246

Energy Technology Data Exchange (ETDEWEB)

Gay, Arnaud; Gillet, Philippe; Ytournel, Bertrand; Varet, Thierry; David, Laurent; Prevost, Thierry; Redonnet, Carol; Piot, Gregoire; Jouaville, Stephane; Pagis, Georges [AREVA NC (France)

2012-07-01

In the wake of the March 11 earthquake and tsunami and the subsequent flooding of several of the Fukushima Dai-Ichi reactors, Japan and the Japanese utility TEPCO faced a crisis situation with incredible challenges: substantial amounts of radioactive mixed seawater and freshwater accumulated in the basements of four reactor and other buildings on the site. This water held varying levels of contamination due to the fact that it had been in contact with damaged fuel elements in the cores and with other contaminated components. The overall water inventory was estimated at around 110,000 tons of water with contamination levels up to the order of 1 Ci/l. Time was of the essence to avoid overflow of this accumulated water into the ocean. AREVA proposed, designed and implemented a water treatment solution using a proven chemical coprecipitation process with ppFeNi reagent, which is currently in use for effluent treatment on several nuclear sites including AREVA sites. In addition to the extremely short schedule the other challenge was to adapt the chemical treatment process to the expected composition of the Fukushima water and, in particular, to evaluate the impact of salinity on process performance. It was also necessary to define operating conditions for the VEOLIA equipment that had been selected for implementation of the process in the future facility. The operation phase began on June 17, and by the end of July more than 30,000 tons of highly radioactive saltwater had been decontaminated - the Decontamination Factor (DF) for Cesium was ∼10{sup 4}. It allowed recycling the contaminated water to cool the reactors while protecting workers and the environment. This paper focuses on the Actiflo{sup TM}-Rad water treatment unit project that was part of the TEPCO general water treatment scheme. It presents a detailed look at the principles of the Actiflo{sup TM}-Rad, related on-the-fly R and D, an explanation of system implementation challenges, and a brief summary of

Re-suspension of Cesium-134/137 into the Canadian Environment and the Contribution Stemming from the Fukushima-Daiichi Nuclear Incident

Science.gov (United States)

Mercier, Jean-Francois; Zhang, Weihua; Loignon-Houle, Francis; Cooke, Michael W.; Ungar, Kurt R.; Pellerin, Eric R.

2013-04-01

Cesium-137 (t1/2 = 30 yr) and cesium-134 (t1/2 = 2yr) constitute major fission by-products observed as the result of a nuclear incident. Such radioisotopes become integrated into the soil and biomass, and can therefore undergo re-suspension into the environment via activities such as forest fires. The Canadian Radiological Monitoring Network (CRMN), which consists of 26 environmental monitoring stations spread across the country, commonly observes cesium-137 in air filters due to re-suspension of material originating from long-past weapons testing. Cesium-134 is not observed owing to its relatively short half-life. The Fukushima-Daiichi nuclear power plant incident of March 2011 caused a major release of radioactive materials into the environment. In Canada, small quantities of both cesium-137 and cesium-134 fallout were detected with great frequency in the weeks which followed, falling off rapidly beginning in July 2011. Since September 2011, the CRMN has detected both cesium-137 and cesium-134 from air filters collected at Yellowknife, Resolute, and Quebec City locations. Using the known initial cesium-134/cesium-137 ratio stemming from this incident, along with a statistical assessment of the normality of the data distribution, we herein present evidence that strongly suggests that these activity spikes are due to re-suspended hot particles originating from the Fukushima-Daiichi nuclear power plant incident. Moreover, we have evidence to suggest that this re-suspension is localized in nature. This study provided empirical insight into the transport and uptake of radionuclides over vast distances, and it demonstrates that the CRMN was able to detect evidence of a re-suspension of Fukushima-Daiichi related isotopes.

Safety technical investigation activities for shipment of damaged spent fuels from Fukushima Daiichi Nuclear Power Station

Energy Technology Data Exchange (ETDEWEB)

NONE

2013-08-15

Japan Nuclear Energy Safety Organization(JNES) carries out the investigation for damaged fuel transportation from Fukushima Daiichi Nuclear Power Station(1F) under safety condition to support Nuclear Regulation Authority (NRA). In 2012 fiscal year, JNES carried out the investigation of spent fuel condition in unit 4 of 1F and actual result of leak fuel transport in domestic /other countries. From this result, Package containing damaged fuel from unit 4 in 1F were considered. (author)

Fukushima Daiichi Unit 1 power plant containment analysis using GOTHIC

International Nuclear Information System (INIS)

Ozdemir, Ozkan Emre; George, Thomas L.; Marshall, Mervin D.

2015-01-01

Highlights: • The inclusion of vent heat transfer had a significant impact on the overall containment response. • The vent heat transfer and condensation results in lower containment pressure. • The reduced gas transfer to the wetwell via the vents results in higher hydrogen concentration in the drywell. - Abstract: This paper is a part of Fukushima Technical Evaluation Project (EPRI, 2013a, 2014a, 2015) which investigates various aspects of the Fukushima Daiichi event using the GOTHIC code. The analysis takes advantage of the capability of GOTHIC to model certain aspects of the system geometry and behavior in more detail than typically considered in containment performance analysis. GOTHIC is a general purpose thermal hydraulics code that is used extensively in the nuclear industry for system design support, licensing support and safety analysis. It has the capability to model 3-dimensional flow behavior including the effects of turbulence, diffusion and buoyancy (EPRI, 2014b). This allows GOTHIC to be used in cases where mixing effects and stratification are important. The analysis presented here considers the events at Fukushima Daiichi Unit 1 (1F1) following the tsunami and leading up to the time of the hydrogen detonation in the 1F1 Reactor Building. The 1F1 MAAP5 Baseline Scenario (EPRI, 2013b) is used to define the steam, hydrogen and carbon-monoxide source terms from the primary system and the core concrete interaction. The model incorporates three dimensional modeling of the drywell, wetwell and connecting vent system that can predict the 3-dimensional flow patterns and the temperature and gas distributions. The model also includes leakage to the surrounding reactor building and the wetwell vent to the stack. The 3D containment model includes models for the heat transfer from the steam and gas in the drywell vent system to the torus room, wetwell gas space and pool. Inclusion of vent heat transfer had a significant impact on the overall containment

Estimation of marine source-term following Fukushima Dai-ichi accident

International Nuclear Information System (INIS)

Bailly du Bois, P.; Laguionie, P.; Boust, D.; Korsakissok, I.; Didier, D.; Fiévet, B.

2012-01-01

Contamination of the marine environment following the accident in the Fukushima Dai-ichi nuclear power plant represented the most important artificial radioactive release flux into the sea ever known. The radioactive marine pollution came from atmospheric fallout onto the ocean, direct release of contaminated water from the plant and transport of radioactive pollution from leaching through contaminated soil. In the immediate vicinity of the plant (less than 500 m), the seawater concentrations reached 68 000 Bq.L −1 for 134 Cs and 137 Cs, and exceeded 100 000 Bq.L −1 for 131 I in early April. Due to the accidental context of the releases, it is difficult to estimate the total amount of radionuclides introduced into seawater from data obtained in the plant. An evaluation is proposed here, based on measurements performed in seawater for monitoring purposes. Quantities of 137 Cs in seawater in a 50-km area around the plant were calculated from interpolation of seawater measurements. The environmental halftime of seawater in this area is deduced from the time-evolution of these quantities. This halftime appeared constant at about 7 days for 137 Cs. These data allowed estimation of the amount of principal marine inputs and their evolution in time: a total of 27 PBq (12 PBq–41 PBq) of 137 Cs was estimated up to July 18. Even though this main release may be followed by residual inputs from the plant, river runoff and leakage from deposited sediments, it represents the principal source-term that must be accounted for future studies of the consequences of the accident on marine systems. The 137 Cs from Fukushima will remain detectable for several years throughout the North Pacific, and 137 Cs/ 134 Cs ratio will be a tracer for future studies. Highlights: ► Fukushima Dai-ichi accident is the most important artificial radioactive release flux into the sea. ► Quantities of 137 Cs in seawater are deduced from individual measurements. ► Local concentrations in

A digest of the Nuclear Safety Division report on the Fukushima Dai-ichi accident seminar (4). Issues identified by the accident

International Nuclear Information System (INIS)

Moriyama, Kumiaki; Abe, Kiyoharu

2013-01-01

AESJ Nuclear Safety Division published 'Report on the Fukushima Dai-ichi Accident Seminar - what was wrong and what should been down in future-' which would be published as five special articles of the AESJ journal. The Fukushima Dai-ichi accident identified issues of several activities directly related with nuclear safety in the areas of safety design, severe accident management and safety regulations. PRA, operational experiences and safety research could not always contribute safety assurance of nuclear power plant so much. This article (4) summarized technical issues based on related facts of the accident as much as possible and discussed' what was wrong and what should be down in future'. Important issues were identified from defense-in-depth philosophy and lessons learned on safety design were obtained from accident progression analysis. Activities against external events and continuous improvements of safety standards based on latest knowledge were most indispensable. Strong cooperation among experts in different areas was also needed. (T. Tanaka)

Experimental investigation on molten pool representing corium composition at Fukushima Daiichi nuclear power plant

Energy Technology Data Exchange (ETDEWEB)

An, Sang Mo, E-mail: sangmoan@kaeri.re.kr [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yueong-gu, Daejeon, 305-353 (Korea, Republic of); Song, Jin Ho [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yueong-gu, Daejeon, 305-353 (Korea, Republic of); Kim, Jong-Yun [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yueong-gu, Daejeon, 305-353 (Korea, Republic of); Radiochemistry & Nuclear Nonproliferation, University of Science & Technology, Gajeong-ro 217, Yuseong-gu, Daejeon, 34113 (Korea, Republic of); Kim, HwanYeol [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yueong-gu, Daejeon, 305-353 (Korea, Republic of); Naitoh, Masanori [The Institute of Applied Energy, 1-14-2 Nishi-shimbashi, 1-Chome, Minato-ku, Tokyo, 105-0003 (Japan)

2016-09-15

A configuration of molten core in the Fukushima Daiichi NPP (nuclear power plant) was investigated by a melting and solidification experiment. About 5 kg of a mixture, whose composition in terms of weight is UO{sub 2} (60%), Zr + ZrO{sub 2} (25%), stainless steel (14%), B{sub 4}C (1%), was melted in a cold crucible using an induction heating technique. It was shown that the solidified melt consists of upper crust and lower solidified ingot. The solidified ingot was separated into two layers. A physical and chemical analysis was performed for the samples taken from the solidified melt to investigate the morphology and chemical characteristics. It was found that the solidified ingot consists of a metal-rich layer on the top and an oxide-rich layer at the bottom. In addition, the oxide layer at the bottom has composition close to the initial charge composition and surrounded by a thin crust layer. It turned out that B{sub 4}C was more concentrated in the upper metal-rich layer. These findings provide important insights for understanding the core melt progression and taking proper post-accident recovery actions for the Fukushima Daiichi NPP. - Highlights: • A configuration of molten core in the Fukushima Daiich NPP unit 1 is investigated. • Corium ingot consists of metallic layer on the top and oxidic layer at the bottom. • Boron carbide was more concentrated in the upper metallic layer. • Two layered configuration would contribute to the post-accident recovery actions.

AESJ 5 years activities and issues to be solved for the TEPCO's Fukushima Daiichi accident

International Nuclear Information System (INIS)

Uetsuka, Hiroshi; Yamamoto, Akio; Saso, Michitaka

2016-01-01

This paper summarizes the measures taken by the Atomic Energy Society of Japan (AESJ) against the Fukushima Daiichi Accident, and its challenges to the task to be addressed in the future. As recommendations by AESJ, the following five items were pointed out in its final report on the survey on the accident: (1) basic matters on nuclear safety, (2) matters on direct causes of accident, (3) organizational matters among background factors, (4) collective matters, and (5) future matters related to environmental remediation. As the commitment to the Fukushima reconstruction, AESJ performed the introduction of decontamination technologies, hosting of interactive forum and symposium session in Fukushima Prefecture, decontamination test of paddy fields, and preparation of an air dose rate map in Fukushima Prefecture. As for the decommissioning of the Fukushima Daiichi Nuclear Power Station, AESJ prepared guidelines by applying probabilistic risk assessment (PRA) to tsunami, and revised seismic PRA standards. Since there was a lack in the implementation of multiple protections as one of the background causes of the Fukushima Accident, it summarized 'concept of the implementation of multiple protections.' In addition, it surveyed and examined the accident from the viewpoint of human factors, discussed the importance of accident investigation from the viewpoint of a party in charge, and issued a report. (A.O.)

The reactor accident in Fukushima Daiichi. The consequence of design deficiencies and inadequate safety engineering; Der Reaktorunfall in Fukushima Daiichi. Folge fehlerhafter Auslegung und unzureichender Sicherheitstechnik

Energy Technology Data Exchange (ETDEWEB)

NONE

2015-03-15

The reactor accident in Fukushima Daiichi is discussed in the frame of design deficiencies and inadequate safety engineering. The progress of the accident as consequence of the earthquake and the tsunami is described. The radiological situation for the public is supposed to be blow the dose limit of 20 mSv/year. The WHO and UNSCEAR (United Nations Scientific Committee on the Effects of Atomic radiation) did not observe acute radiation injuries. The Japanese authorities have classified the accident to 7 of the INES scale. The German Atomforum e.V. considers the safety engineering of German NPPs to be superior to the Japanese situation due to higher emergency energy supply, extensive measures to reduce the hydrogen accumulation and mitigating measures for the accident management. German NPPS are considered highly robust as the EU stress tests have shown.

Enhancement of organizational resilience in light of the Fukushima Dai-ichi Nuclear Power Plant accident (1). Analysis of responding structure

International Nuclear Information System (INIS)

Yoshizawa, Atsufumi; Furuhama, Yutaka; Mutou, Keiko; Oba, Kyoko; Kitamura, Masaharu

2014-01-01

Through the critical situations experienced at the Fukushima Daiichi Nuclear Power Plant accident, it became evident that plant personnel are the essential driving force toward resilience for mitigating the severe nuclear accident. In such situation, the key factors are skill and attitude of human operators who struggled sincerely against the accident. It is also evident that future nuclear safety needs to aim at Safety- which is a newly introduced notion of safety proposed in conjunction with resilience engineering. Safety-I was defined as a condition where as little as possible went wrong;. Safety-II is defined as a condition where as much as possible goes wright. Among the four core capabilities (i.e. Learning, Responding, Monitoring, Anticipating) proposed in the framework of resilience engineering, the constituents of 'Responding' is mainly studied in this paper. Four constituents such as Skill Attitude, Health and Environment have been identified through in-depth reviewing of accident reports and reflection of one of the authors who served as a unit director of Fukushima Daiichi Nuclear Power Plant. (author)

Radioactivity around Fukushima Daiichi Nuclear Power Plant 9 months after the disaster

International Nuclear Information System (INIS)

Shozugawa, Katsumi

2012-01-01

We have measured radioactivities around Fukushima Daiichi Nuclear Power Plant in December, 2011, 9 months after the disaster, to compare with measurements in April, 2011. The radioactivity originated by radioactive iodine should have disappeared before December due to its comparatively short lifetime. At the point 1.5km apart from the Plant, the dose rate 1m above the earth was 78 μ Sv/h in April whereas it was 56 μ Sv/h in December, which was higher than anticipation. The measured radioactivities of the soil of fields and forests around the Plant in December were even four times higher than those in April. These phenomena may be resulted with the movement of soil particles attached with radioactive cesium by rainwater or wind. (author)

Research of the improvement of the process, organization, etc. related to the emergency correspondence of JNES based on the cause analysis about emergency correspondence of JNES in case of the Fukushima Dai-ichi nuclear power plant accident

Energy Technology Data Exchange (ETDEWEB)

NONE

2013-08-15

At the time of the occurrence of the Fukushima Dai-ichi nuclear power plant accident, JNES implemented various emergency correspondences. On the other hand, various organizations published the report about the Fukushima Dai-ichi nuclear power plant accident. In them, the problems about the regulatory body's regulatory process, regulatory organization, etc. are also pointed out. JNES is a designated public institution. JNES is required to improve process, organization, etc. related to emergency correspondence continuously based on the lessons learned obtained from the emergency corresponding experience about the Fukushima Dai-ichi nuclear power plant accident. Specifically, the following activities will be implemented in the 2014 and 2015 fiscal year. 1. Collect systematically and comprehensively the information about emergency correspondence of JNES in case of the Fukushima Dai-ichi nuclear power plant accident, and create the timeline of the event. 2. Specify problems and analyze human factors and organizational factors. 3. Specify the requirements for establishing a designated public institution's emergency correspondence based on the viewpoint of a human and an organization. 4. Publish the report which indicates collected information, the contents of analysis, proposals of improvement, etc. (author)

Implementation of Defence in Depth at Nuclear Power Plants. Lessons Learnt from the Fukushima Daiichi Accident

International Nuclear Information System (INIS)

Lachaume, Jean-Luc; Miller, Douglass; Rzentkowski, Greg; Lahtinen, Nina; Valtonen, Keijo; Foucher, Laurent; Harikumar, Shri S.; Yamada, Tomoho; Sharafutdinov, Rashet; Kuznetsov, Mark; Carlsson, Lennart; Hanberg, Jan; Theiss, Klaus; Holahan, Gary; Williams, Donna; Nuenighoff, Kay; Wattelle, Emmanuel; Lazo, Edward; White, Andrew; Reig, Javier; Salgado, Nancy; Weightman, Mike

2016-01-01

Defence in depth (DiD) is a concept that has been used for many years alongside tools to optimise nuclear safety in reactor design, assessment and regulation. The 2011 Fukushima Daiichi nuclear power plant accident raised many questions and gave unique insight into nuclear safety issues, including DiD. In June 2013, the NEA held a Joint Workshop on Challenges and Enhancements to DiD in Light of the Fukushima Daiichi Accident (NEA, 2014), organised by the NEA Committee on the Safety of Nuclear Installations (CSNI) and the NEA Committee on Nuclear Regulatory Activities (CNRA). It was noted at the time that further work would be beneficial to enhance nuclear safety worldwide, especially with regard to the implementation of DiD. Accordingly, a senior-level task group (STG) was set up to produce a regulatory guidance booklet that would assist member countries in the use of DiD, taking into account lessons learnt from the 2011 accident. This regulatory guidance booklet builds on the work of this NEA workshop, of the International Atomic Energy Agency (IAEA), the Western European Nuclear Regulators Association (WENRA) and of other members of the STG. It uses as its basis the International Nuclear Safety Advisory Group's Defence in Depth in Nuclear Safety study (INSAG-10) (IAEA, 1996). The booklet provides insights into the implementation of DiD by regulators and emergency management authorities after the Fukushima Daiichi accident, aiming to enhance global harmonisation by providing guidance on: - the background to the DiD concept; - the need for independent effectiveness among the safety provisions for the various DiD levels, to the extent practicable; - the need for greater attention to reinforce prevention and mitigation at the various levels; - the vital importance of ensuring that common cause and common mode failures, especially external events acting in combination, do not lead to breaches of safety provisions at several DiD levels, taking note of the

Fukushima Daiichi-Derived Radionuclides in the Ocean: Transport, Fate, and Impacts.

Science.gov (United States)

Buesseler, Ken; Dai, Minhan; Aoyama, Michio; Benitez-Nelson, Claudia; Charmasson, Sabine; Higley, Kathryn; Maderich, Vladimir; Masqué, Pere; Morris, Paul J; Oughton, Deborah; Smith, John N

2017-01-03

The events that followed the Tohoku earthquake and tsunami on March 11, 2011, included the loss of power and overheating at the Fukushima Daiichi nuclear power plants, which led to extensive releases of radioactive gases, volatiles, and liquids, particularly to the coastal ocean. The fate of these radionuclides depends in large part on their oceanic geochemistry, physical processes, and biological uptake. Whereas radioactivity on land can be resampled and its distribution mapped, releases to the marine environment are harder to characterize owing to variability in ocean currents and the general challenges of sampling at sea. Five years later, it is appropriate to review what happened in terms of the sources, transport, and fate of these radionuclides in the ocean. In addition to the oceanic behavior of these contaminants, this review considers the potential health effects and societal impacts.

Fukushima Daiichi Unit 1 Ex-Vessel Prediction: Core Concrete Interaction

International Nuclear Information System (INIS)

Robb, Kevin R; Farmer, Mitchell; Francis, Matthew W

2015-01-01

Lower head failure and corium concrete interaction were predicted to occur at Fukushima Daiichi Unit 1 (1F1) by several different system-level code analyses, including MELCOR v2.1 and MAAP5. Although these codes capture a wide range of accident phenomena, they do not contain detailed models for ex-vessel core melt behavior. However, specialized codes exist for analysis of ex-vessel melt spreading (e.g., MELTSPREAD) and long-term debris coolability (e.g., CORQUENCH). On this basis, an analysis was carried out to further evaluate ex-vessel behavior for 1F1 using MELTSPREAD and CORQUENCH. Best-estimate melt pour conditions predicted by MELCOR v2.1 and MAAP5 were used as input. MELTSPREAD was then used to predict the spatially dependent melt conditions and extent of spreading during relocation from the vessel. The results of the MELTSPREAD analysis are reported in a companion paper. This information was used as input for the long-term debris coolability analysis with CORQUENCH.

[Measures against Radiation Exposure Due to Large-Scale Nuclear Accident in Distant Place--Radioactive Materials in Nagasaki from Fukushima Daiichi Nuclear Power Plant].

Science.gov (United States)

Yuan, Jun; Sera, Koichiro; Takatsuji, Toshihiro

2015-01-01

To investigate human health effects of radiation exposure due to possible future nuclear accidents in distant places and other various findings of analysis of the radioactive materials contaminating the atmosphere of Nagasaki due to the Fukushima Daiichi Nuclear Power Plant accident. The concentrations of radioactive materials in aerosols in the atmosphere of Nagasaki were measured using a germanium semiconductor detector from March 2011 to March 2013. Internal exposure dose was calculated in accordance with ICRP Publ. 72. Air trajectories were analyzed using NOAA and METEX web-based systems. (134)Cs and (137)Cs were repeatedly detected. The air trajectory analysis showed that (134)Cs and (137)Cs flew directly from the Fukushima Daiichi Nuclear Power Plant from March to April 2011. However, the direct air trajectories were rarely detected after this period even when (134)Cs and (137)Cs were detected after this period. The activity ratios ((134)Cs/(137)Cs) of almost all the samples converted to those in March 2011 were about unity. This strongly suggests that the (134)Cs and (137)Cs detected mainly originated from the Fukushima Daiichi Nuclear Power Plant accident in March 2011. Although the (134)Cs and (137)Cs concentrations per air volume were very low and the human health effects of internal exposure via inhalation is expected to be negligible, the specific activities (concentrations per aerosol mass) were relatively high. It was found that possible future nuclear accidents may cause severe radioactive contaminations, which may require radiation exposure control of farm goods to more than 1000 km from places of nuclear accidents.

Review of Cytogenetic analysis of restoration workers for Fukushima Daiichi nuclear power station accident

International Nuclear Information System (INIS)

Suto, Yumiko

2016-01-01

Japan faced with the nuclear accident of the Fukushima Daiichi Nuclear Power Station (NPS) caused by the combined disaster of the Great East Japan Earthquake and the subsequent tsunamis on 11 March 2011. National Institute of Radiological Sciences received all nuclear workers who were engaged in emergency response tasks at the NPS and suspected of being overexposed to acute radiation. Biological dosimetry by dicentric chromosome assay was helpful for medical triage and management of the workers. When an unplanned radiation exposure occurs, biological dosimetry based on cytogenetic assays has been used to estimate the absorbed dose in the exposed individual to get useful information for the medical management of radiological casualties with suspected acute radiation syndrome (ARS). Nowadays, more cytogenetic assays to measure chromosomal aberrations, such as micronuclei in bi-nucleated cells, prematurely condensed chromosomes (PCCs) and inter-chromosomal exchanges detected by fluorescence in situ hybridization (FISH) techniques, are available. However, the dicentric chromosome assay (DCA) using peripheral blood lymphocytes is still considered to be the 'gold standard' of biological dosimetry for the radiation emergency medicine. Experimental protocols of DCA has been standardized and shared among laboratories all over the world. In fact, DCA was useful in previous radiation accidents, e.g. the Chernobyl accident in 1986, the Goiania accident in 1987, the JCO criticality accident in 1999 and the Tokyo electric power company (TEPCO) Fukushima Daiichi Nuclear Power Station (NPS) accident in 2011. The recent development of microscopic image analysis system with automatic metaphase finding and capturing functions was helpful for rapid detection of dicentric chromosomes to perform DCA for the Fukushima NPS restoration workers. (author)

Fungal levels in houses in the Fukushima Daiichi Nuclear Power Plant evacuation zone after the Great East Japan Earthquake.

Science.gov (United States)

Shinohara, Naohide; Tokumura, Masahiro; Hashimoto, Kazuhiro; Asano, Katsuyoshi; Kawakami, Yuji

2017-10-01

Residences located within 20 km of the damaged Fukushima Daiichi Nuclear Power Plant were evacuated shortly after the Great East Japan Earthquake. The levels of airborne and surface fungi were measured in six houses in the evacuation zone in August 2012 and February 2013. Airborne fungal levels in all of the houses in the summer were higher than the environmental standard levels for residential houses published in Architectural Institute of Japan (>1000 colony-forming units [CFU]/m 3 ). In two houses whose residents rarely returned to visit, fungal levels were extremely high (>52,000 CFU/m 3 ). Although fungal levels in the winter were much lower than those in the summer, they were still higher than environmental standard levels in several houses. Indoor fungal levels were significantly inversely related to the frequency with which residents returned, but they were not correlated with the air exchange rates, temperature, humidity, or radiation levels. Cladosporium spp. and Penicillium spp. were detected in every house. Aspergillus section Circumdati (Aspergillus ochraceus group) was also detected in several houses. These fungi produced ochratoxin A and ochratoxin B, which have nephrotoxic and carcinogenic potential. The present study suggests that further monitoring of fungal levels is necessary in houses in the Fukushima Daiichi Nuclear Power Plant evacuation zone, and that some houses may require fungal disinfection. The results suggest that residents' health could be at risk owing to the high levels of airborne fungi and toxic fungi Aspergillus section Circumdati. Therefore, monitoring and decontamination/disinfection of fungi are strongly recommended before residents are allowed to return permanently to their homes. In addition, returning to home with a certain frequency and adequate ventilation are necessary during similar situations, e.g., when residents cannot stay in their homes for a long period, because fungal levels in houses in the Fukushima Daiichi

Status of the spent fuel in the reactor buildings of Fukushima Daiichi 1–4

Energy Technology Data Exchange (ETDEWEB)

Jäckel, Bernd S., E-mail: bernd.jaeckel@psi.ch

2015-03-15

The ratios of the radionuclides Cs-134g and Cs-137 deduced from measurements of liquid samples from the spent fuel pools in Fukushima Daiichi 1–4 are used to interpret the status of the spent fuel assemblies in the pools of the damaged reactor buildings. The different natures of the production of Cs-134g (neutron capture product of Cs-133) and Cs-137 (cumulative fission product from mass chain 137) and the different half-lives (2.06 years and 30.17 years respectively) require a complicated calculation of the mass and activity of the two nuclides. These masses are depending on the local burn up of the fuel, the burn up history and the radioactive decay. Calculation of the neutron capture product Cs-134g is particularly complicated, because the production of Cs-133 (stable cumulative fission product from mass chain 133) has to be taken into account. The neutron capture cross section for Cs-133 for thermal neutrons is well known, but the energy spectrum of the neutrons in a reactor includes higher energies according to the degree of moderation. Therefore the cross section was fitted from a gamma scan of spent fuel rods in a hot cell. The method of the calculation of the nuclide activities and the interpretation of the gamma measurements of the spent fuel pool samples from Fukushima Daiichi 1–4 are described in detail. It could be shown that at most only very minor mechanical damage of some spent fuel elements occurred during the accident and the later phase of the clearing work.

Lessons Learned from the Fukushima Daiichi Accident, Actions Taken and Challenges Ahead

International Nuclear Information System (INIS)

Shimizu, Y.

2016-01-01

On 19 September, 2012, the Nuclear Regulation Authority (NRA) was established in light of lessons learned from the Fukushima Daiichi accident of 11 March 2011, to ensure that such accidents never happen again, to restore public trust in regulator both in Japan and abroad and to rebuild and foster a genuine safety culture by placing the highest priority on public safety. The NRA, an independent administrative commission of the Ministry of the Environment, is organized to separate the regulatory functions from the promotional functions of the use of nuclear energy within the government, and to independently implement its duties from the perspectives of neutrality and fairness based on its expertise. Having learned the lessons from the Fukushima Daiichi accident and with reference to IAEA safety standards, since its establishment, the NRA has endeavored to strengthen the regulatory requirements, in particular, for hazards such as tsunamis and earthquakes which may lead to common cause failures, and countermeasures against severe accidents. Under the new regulatory scheme, a back-fitting system was introduced. Emergency preparedness and response measures for nuclear facilities were also enhanced. As of end of March 2016, five reactors received NRA’s permission for changing their reactor installations based on the new regulatory requirements, and two nuclear power reactors have restarted their operations. In January 2016, at the request of Japan, the IAEA sent the IRRS mission team to Japan to assess the regulatory framework for nuclear and radiation safety. Through the self-assessment prior to the mission, the NRA has developed 22 action plans, including a) improvement of regulatory inspection, b) capacity building, and c) strengthening of safety research capability. The mission team has found that Japan’s nuclear regulator has demonstrated independence and transparency since it was set up in 2012. The team also noted that the NRA needs to improve the inspection

Fukushima Daiichi Nuclear Power Plant accident: facts, environmental contamination, possible biological effects, and countermeasures.

Science.gov (United States)

Anzai, Kazunori; Ban, Nobuhiko; Ozawa, Toshihiko; Tokonami, Shinji

2012-01-01

On March 11, 2011, an earthquake led to major problems at the Fukushima Daiichi Nuclear Power Plant. A 14-m high tsunami triggered by the earthquake disabled all AC power to Units 1, 2, and 3 of the Power Plant, and carried off fuel tanks for emergency diesel generators. Despite many efforts, cooling systems did not work and hydrogen explosions damaged the facilities, releasing a large amount of radioactive material into the environment. In this review, we describe the environmental impact of the nuclear accident, and the fundamental biological effects, acute and late, of the radiation. Possible medical countermeasures to radiation exposure are also discussed.

Dispersion and fate of {sup 90}Sr in the Northwestern Pacific and adjacent seas: Global fallout and the Fukushima Dai-ichi accident

Energy Technology Data Exchange (ETDEWEB)

Maderich, V., E-mail: vladmad@gmail.com [Institute of Mathematical Machine and System Problems, Glushkov av., 42, Kiev 03187 (Ukraine); Jung, K.T., E-mail: ktjung@kiost.ac [Korea Institute of Ocean Science and Technology, 787, Haean-ro, Ansan 426-744 (Korea, Republic of); Bezhenar, R., E-mail: romanbezhenar@gmail.com [Ukrainian Center of Water and Environmental Projects, Glushkov av., 42, Kiev 03187 (Ukraine); With, G. de, E-mail: g.dewith@nrg.eu [NRG, Utrechtseweg 310, 6800 ES Arnhem (Netherlands); Qiao, F., E-mail: qiaofl@fio.org.cn [First Institute of Oceanography, 6 Xianxialing Road, Qingdao 266061 (China); Casacuberta, N., E-mail: ncasacuberta@phys.ethz.ch [Laboratory of Ion Beam Physics, ETH-Zurich, Schafmattstrasse 20, 8093 Zurich (Switzerland); Masque, P., E-mail: pere.masque@uab.cat [Institut de Ciència i Tecnologia Ambientals and Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra (Spain); Kim, Y.H., E-mail: yhkimstar@gmail.com [Korea Institute of Ocean Science and Technology, 787, Haean-ro, Ansan 426-744 (Korea, Republic of)

2014-10-01

The 3D compartment model POSEIDON-R was applied to the Northwestern Pacific and adjacent seas to simulate the transport and fate of {sup 90}Sr in the period 1945–2010 and to perform a radiological assessment on the releases of {sup 90}Sr due to the Fukushima Dai-ichi nuclear accident for the period 2011–2040. The contamination due to runoff of {sup 90}Sr from terrestrial surfaces was taken into account using a generic predictive model. A dynamical food-chain model describes the transfer of {sup 90}Sr to phytoplankton, zooplankton, molluscs, crustaceans, piscivorous and non-piscivorous fishes. Results of the simulations were compared with observation data on {sup 90}Sr for the period 1955–2010 and the budget of {sup 90}Sr activity was estimated. It was found that in the East China Sea and Yellow Sea the riverine influx was 1.5% of the ocean influx and it was important only locally. Calculated concentrations of {sup 90}Sr in water, bottom sediment and marine organisms before and after the Fukushima Dai-ichi accident are in good agreement with available experimental measurements. The concentration of {sup 90}Sr in seawater would return to the background levels within one year after leakages were stopped. The model predicts that the concentration of {sup 90}Sr in fish after the Fukushima Dai-ichi accident shall return to the background concentrations only 2 years later due to the delay of the transfer throughout the food web and specific accumulation of {sup 90}Sr. The contribution of {sup 90}Sr to the maximal dose rate due to the FDNPP accident was three orders of magnitude less than that due to {sup 137}Cs, and thus well below the maximum effective dose limits for the public. - Highlights: • A box model with a dynamical food-chain model for the NW Pacific was applied. • The transport and fate of {sup 90}Sr in sea were simulated for the period 1945–2040. • Marine exposure pathways for {sup 90}Sr were assessed for the Fukushima Dai-ichi accident. �

Analytics of Radioactive Materials Released in the Fukushima Daiichi Nuclear Accident

Energy Technology Data Exchange (ETDEWEB)

Egarievwe, Stephen U. [Nuclear Engineering and Radiological Science Center, Alabama A and M University, Huntsville, AL (United States); Nuclear Engineering Department, University of Tennessee, Knoxville, TN (United States); Coble, Jamie B.; Miller, Laurence F. [Nuclear Engineering Department, University of Tennessee, Knoxville, TN (United States)

2015-07-01

The 2011 Fukushima Daiichi nuclear accident in Japan resulted in the release of radioactive materials into the atmosphere, the nearby sea, and the surrounding land. Following the accident, several meteorological models were used to predict the transport of the radioactive materials to other continents such as North America and Europe. Also of high importance is the dispersion of radioactive materials locally and within Japan. Based on the International Atomic Energy Agency (IAEA) Convention on Early Notification of a nuclear accident, several radiological data sets were collected on the accident by the Japanese authorities. Among the radioactive materials monitored, are I-131 and Cs-137 which form the major contributions to the contamination of drinking water. The radiation dose in the atmosphere was also measured. It is impractical to measure contamination and radiation dose in every place of interest. Therefore, modeling helps to predict contamination and radiation dose. Some modeling studies that have been reported in the literature include the simulation of transport and deposition of I-131 and Cs-137 from the accident, Cs-137 deposition and contamination of Japanese soils, and preliminary estimates of I-131 and Cs-137 discharged from the plant into the atmosphere. In this paper, we present statistical analytics of I-131 and Cs-137 with the goal of predicting gamma dose from the Fukushima Daiichi nuclear accident. The data sets used in our study were collected from the IAEA Fukushima Monitoring Database. As part of this study, we investigated several regression models to find the best algorithm for modeling the gamma dose. The modeling techniques used in our study include linear regression, principal component regression (PCR), partial least square (PLS) regression, and ridge regression. Our preliminary results on the first set of data showed that the linear regression model with one variable was the best with a root mean square error of 0.0133 μSv/h, compared

Analytics of Radioactive Materials Released in the Fukushima Daiichi Nuclear Accident

International Nuclear Information System (INIS)

Egarievwe, Stephen U.; Coble, Jamie B.; Miller, Laurence F.

2015-01-01

The 2011 Fukushima Daiichi nuclear accident in Japan resulted in the release of radioactive materials into the atmosphere, the nearby sea, and the surrounding land. Following the accident, several meteorological models were used to predict the transport of the radioactive materials to other continents such as North America and Europe. Also of high importance is the dispersion of radioactive materials locally and within Japan. Based on the International Atomic Energy Agency (IAEA) Convention on Early Notification of a nuclear accident, several radiological data sets were collected on the accident by the Japanese authorities. Among the radioactive materials monitored, are I-131 and Cs-137 which form the major contributions to the contamination of drinking water. The radiation dose in the atmosphere was also measured. It is impractical to measure contamination and radiation dose in every place of interest. Therefore, modeling helps to predict contamination and radiation dose. Some modeling studies that have been reported in the literature include the simulation of transport and deposition of I-131 and Cs-137 from the accident, Cs-137 deposition and contamination of Japanese soils, and preliminary estimates of I-131 and Cs-137 discharged from the plant into the atmosphere. In this paper, we present statistical analytics of I-131 and Cs-137 with the goal of predicting gamma dose from the Fukushima Daiichi nuclear accident. The data sets used in our study were collected from the IAEA Fukushima Monitoring Database. As part of this study, we investigated several regression models to find the best algorithm for modeling the gamma dose. The modeling techniques used in our study include linear regression, principal component regression (PCR), partial least square (PLS) regression, and ridge regression. Our preliminary results on the first set of data showed that the linear regression model with one variable was the best with a root mean square error of 0.0133 μSv/h, compared

Radiation protection management in Fukushima Daiichi NPS and post-accident measures

International Nuclear Information System (INIS)

Takahira, Shiro

2014-01-01

Fukushima Daiichi Nuclear Power Station was hit by the big earthquake and tsunami, which caused the station black out and subsequent loss of cooling functions for reactor and spent fuel pools (SFPs). Consequently the fuels were damaged, hydrogen explosion blew off top of the reactor buildings and radioactive materials were released to the atmosphere and the ocean. Tsunami and power loss caused many difficulties of monitoring, dose management, and radiation protection of workers. For example, the radiation management system was down and about 5,000 Alarm Pocket Dosimeters (APDs) and their battery chargers could not be used. Due to the insufficient number of APDs, one representative of each working team had a dosimeter under the limited conditions. Through the accident, we got following lessons learned; (1) Reinforcing monitoring posts, (2) Preparing more radiation protection equipment, (3) Establishing emergency access control centre, and (4) Education and training in radiation protection. (author)

Consumer Perceptions of Seafood Industries in the Wake of the Deepwater Horizon Oil Spill and Fukushima Daiichi Nuclear Disaster

OpenAIRE

McKendree, Melissa G.S.; Ortega, David L.; Widmar, Nicole Olynk; Wang, H. Holly

2013-01-01

The impact of environmental disasters on consumers’ perceptions and preferences for specific food items has seldom been studied in the applied economics literature. Recent aquatic disasters, namely the Deepwater Horizon Oil Spill and Fukushima Daiichi Nuclear Disaster, have had profound impacts on fisheries serving US consumers and on agribusinesses within the aquaculture industry. This study explores consumer preferences using a nation-wide representative sample, and finds that twenty-nine p...

The cross-section of returns, benchmark model parameters, and idiosyncratic volatility of nuclear energy firms after Fukushima Daiichi

International Nuclear Information System (INIS)

Lopatta, Kerstin; Kaspereit, Thomas

2014-01-01

This study analyzes how the stock market returns, the factor loadings from the Carhart (1997) 4-factor model, and the idiosyncratic volatility of shares in energy firms have been affected by the Fukushima nuclear accident. Unlike existing studies, which provide evidence of a wealth transfer from nuclear to renewable energy firms for specific countries, we use an international sample and investigate whether changes in the regulatory environment and the firm-specific commitment to nuclear and renewable energies correlate with the capital market's reactions to the Fukushima Daiichi accident. Our findings suggest that the more a firm relies on nuclear power, the more its share price declined after the accident. A commitment to renewable energies does not prevent declines in share prices but significantly helps to reduce the increase in market beta that is associated with this event. Nuclear energy firms domiciled in countries with a higher number of regulatory interventions that were triggered by the catastrophe have lower abnormal returns than those that are domiciled elsewhere. However, as a cross-sectional analysis reveals, a stronger commitment to nuclear power is the main driver for negative stock market returns. Furthermore, nuclear energy firms domiciled in countries with stronger regulatory shifts away from nuclear energy experience significant increases in market beta and the book-to-market equity factor loading according to the Carhart (1997) 4-factor model. We conclude that capital market participants are able to differentiate between the affectedness of firms with respect to their product portfolio. Energy firms could prevent increases in market beta due to catastrophes such as the Fukushima Daiichi accident by shifting some of their energy production from nuclear to renewable or other sources. - Highlights: • Abnormal stock returns of nuclear energy firms around Fukushima Daiichi depend on the mix of their energy portfolio. • Higher commitment to

NARAC Modeling During the Response to the Fukushima Dai-ichi Nuclear Power Plant Emergency

Energy Technology Data Exchange (ETDEWEB)

Sugiyama, G; Nasstrom, J S; Probanz, B; Foster, K T; Simpson, M; Vogt, P; Aluzzi, F; Dillon, M; Homann, S

2012-02-14

This paper summarizes the activities of the National Atmospheric Release Advisory Center (NARAC) during the Fukushima Dai-ichi nuclear power plant crisis. NARAC provided a wide range of products and analyses as part of its support including: (1) Daily Japanese weather forecasts and hypothetical release (generic source term) dispersion predictions to provide situational awareness and inform planning for U.S. measurement data collection and field operations; (2) Estimates of potential dose in Japan for hypothetical scenarios developed by the Nuclear Regulatory Commission (NRC) to inform federal government considerations of possible actions that might be needed to protect U.S. citizens in Japan; (3) Estimates of possible plume arrival times and dose for U.S. locations; and (4) Plume model refinement and source estimation based on meteorological analyses and available field data. The Department of Energy/National Nuclear Security Administration (DOE/NNSA) deployed personnel to Japan and stood up 'home team' assets across the DOE complex to aid in assessing the consequences of the releases from the Fukushima Dai-ichi Nuclear Power Plant. The DOE Nuclear Incident Team (NIT) coordinated response activities, while DOE personnel provided predictive modeling, air and ground monitoring, sample collection, laboratory analysis, and data assessment and interpretation. DOE deployed the Aerial Measuring System (AMS), Radiological Assistance Program (RAP) personnel, and the Consequence Management Response Team (CMRT) to Japan. DOE/NNSA home team assets included the Consequence Management Home Team (CMHT); National Atmospheric Release Advisory Center (NARAC); Radiation Emergency Assistance Center/Training Site (REAC/TS); and Radiological Triage. NARAC was activated by the DOE/NNSA on March 11, shortly after the Tohoku earthquake and tsunami occurred. The center remained on active operations through late May when DOE ended its deployment to Japan. Over 32 NARAC staff

NARAC Modeling During the Response to the Fukushima Dai-ichi Nuclear Power Plant Emergency

International Nuclear Information System (INIS)

Sugiyama, G.; Nasstrom, J.S.; Probanz, B.; Foster, K.T.; Simpson, M.; Vogt, P.; Aluzzi, F.; Dillon, M.; Homann, S.

2012-01-01

This paper summarizes the activities of the National Atmospheric Release Advisory Center (NARAC) during the Fukushima Dai-ichi nuclear power plant crisis. NARAC provided a wide range of products and analyses as part of its support including: (1) Daily Japanese weather forecasts and hypothetical release (generic source term) dispersion predictions to provide situational awareness and inform planning for U.S. measurement data collection and field operations; (2) Estimates of potential dose in Japan for hypothetical scenarios developed by the Nuclear Regulatory Commission (NRC) to inform federal government considerations of possible actions that might be needed to protect U.S. citizens in Japan; (3) Estimates of possible plume arrival times and dose for U.S. locations; and (4) Plume model refinement and source estimation based on meteorological analyses and available field data. The Department of Energy/National Nuclear Security Administration (DOE/NNSA) deployed personnel to Japan and stood up 'home team' assets across the DOE complex to aid in assessing the consequences of the releases from the Fukushima Dai-ichi Nuclear Power Plant. The DOE Nuclear Incident Team (NIT) coordinated response activities, while DOE personnel provided predictive modeling, air and ground monitoring, sample collection, laboratory analysis, and data assessment and interpretation. DOE deployed the Aerial Measuring System (AMS), Radiological Assistance Program (RAP) personnel, and the Consequence Management Response Team (CMRT) to Japan. DOE/NNSA home team assets included the Consequence Management Home Team (CMHT); National Atmospheric Release Advisory Center (NARAC); Radiation Emergency Assistance Center/Training Site (REAC/TS); and Radiological Triage. NARAC was activated by the DOE/NNSA on March 11, shortly after the Tohoku earthquake and tsunami occurred. The center remained on active operations through late May when DOE ended its deployment to Japan. Over 32 NARAC staff members

Estimation of average burnup of damaged fuels loaded in Fukushima Dai-ichi reactors by using the 134Cs/137Cs ratio method

International Nuclear Information System (INIS)

Endo, T.; Sato, S.; Yamamoto, A.

2012-01-01

Average burnup of damaged fuels loaded in Fukushima Dai-ichi reactors is estimated, using the 134 Cs/ 137 Cs ratio method for measured radioactivities of 134 Cs and 137 Cs in contaminated soils within the range of 100 km from the Fukushima Dai-ichi nuclear power plants. As a result, the measured 134 Cs/ 137 Cs ratio from the contaminated soil is 0.996±0.07 as of March 11, 2011. Based on the 134 Cs/ 137 Cs ratio method, the estimated burnup of damaged fuels is approximately 17.2±1.5 [GWd/tHM]. It is noted that the numerical results of various calculation codes (SRAC2006/PIJ, SCALE6.0/TRITON, and MVP-BURN) are almost the same evaluation values of 134 Cs/ 137 Cs ratio with same evaluated nuclear data library (ENDF-B/VII.0). The void fraction effect in depletion calculation has a major impact on 134 Cs/ 137 Cs ratio compared with the differences between JENDL-4.0 and ENDF-B/VII.0. (authors)

Emergency feature. Great east Japan earthquake disaster Fukushima Daiichi accident

International Nuclear Information System (INIS)

Kawata, Tomio; Tsujikura, Yonezo; Kitamura, Toshiro

2011-01-01

The Tohoku Pacific Ocean earthquake occurred in March 11, 2011. The disastrous tsunami attacked Fukushima Daiichi nuclear power plants after automatically shutdown by the earthquake and all motor operated pumps became inoperable due to station black out. Despite the strenuous efforts of operators, if caused serious accident such as loss of cooling function, hydrogen explosion and release of large amount of radioactive materials into the environment, leading to nuclear power emergency that ordered resident to evacuate or remain indoors. This emergency feature consisted of four articles. The first was the interview with the president of JAIF (Japan Atomic Industrial Forum) on how to identify the cause of the accident completely, intensify safety assurance measures and promote discussions on a role of nuclear power in the nation's entire energy policy toward the reconstruction. Others were reactor states and events sequence after the accident with trend data of radiation in the reactor site, statement of president of AESJ (Atomic Energy Society of Japan) on nuclear crisis following Tohoku Pacific Ocean earthquake our response and my experience in evacuation life. (T. Tanaka)

IAEA report on the Fukushima-Daiichi accident and safety standards

International Nuclear Information System (INIS)

Mizumachi, Wataru

2011-01-01

On March 11th, 2011, 4th largest earthquake attacked Fukushima Nuclear Power Plant and around one hour later, the enormous Tsunami attacked it also. After the large earthquake attacked, the automatic shutdown was performed and the emergency diesel generators automatically started and Isolation condenser cooled down the core for unit 1 and RCIC cooled down the cores for unit 2 and 3. However, the large Tsunami damaged all emergency diesel generators and all ECCS pumps. The core melted and the hydrogen gas were generated by the steam and the zircaloy reaction. The hydrogen leaked into the reactor building and then the reactor building blasted by the hydrogen. IAEA has organized the Great East Japan Earthquake Expert Mission on Fukushima-daiichi accident and they reported to the formal meeting in the headquater in Viena. They made 15 conclusions and 16 lessons and learned. IAEA chairman officially summarized 28 recommendations from them. USNRC published 'Recommendations for Enhanuing Reactor Safety in the 21st Century 'where they summarized 12 Recommendations on Fukushima Accident. Here is the summary of these recommendations. (author)

Effects of the Fukushima Daiichi nuclear accident on goshawk reproduction

Science.gov (United States)

Murase, Kaori; Murase, Joe; Horie, Reiko; Endo, Koichi

2015-01-01

Although the influence of nuclear accidents on the reproduction of top predators has not been investigated, it is important that we identify the effects of such accidents because humans are also top predators. We conducted field observation for 22 years and analysed the reproductive performance of the goshawk (Accipiter gentilis fujiyamae), a top avian predator in the North Kanto area of Japan, before and after the accidents at the Fukushima Daiichi nuclear power plant that occurred in 2011. The reproductive performance declined markedly compared with the pre-accident years and progressively decreased for the three post-accident study years. Moreover, it was suggested that these declines were primarily caused by an increase in the air dose rate of radio-active contaminants measured under the nests caused by the nuclear accidents, rather than by other factors. We consider the trends in the changes of the reproductive success rates and suggest that internal exposure may play an important role in the reproductive performance of the goshawk, as well as external exposure. PMID:25802117

Analysis on Isolation Condenser Operation by Fukushima Daiichi Unit 1 Operators

International Nuclear Information System (INIS)

Kim, Man Cheol

2014-01-01

Fukushima Daiichi nuclear accident resulted in the core damage in three reactors and the release of considerable amount of radioactive material to the environment, not to mention significant social impact and anti-nuclear atmosphere all around the world. This paper provides a review of the findings related to shift operators' operation of the isolation condenser in Unit 1 to examine shift operators' response to the situation. Based on the review of the findings, a situation assessment model was developed to analyze shift operators' understanding on whether core cooling was successfully performed in Unit 1 through the operation of isolation condenser. It was found that lack of information could be one of the main causes for the failure in core cooling by the IC in Unit 1. It is also recommended that the differences in the mathematical model for the situation assessment and that of the real operator need to be further investigated

Analysis on Isolation Condenser Operation by Fukushima Daiichi Unit 1 Operators

Energy Technology Data Exchange (ETDEWEB)

Kim, Man Cheol [Chungang University, Seoul (Korea, Republic of)

2014-08-15

Fukushima Daiichi nuclear accident resulted in the core damage in three reactors and the release of considerable amount of radioactive material to the environment, not to mention significant social impact and anti-nuclear atmosphere all around the world. This paper provides a review of the findings related to shift operators' operation of the isolation condenser in Unit 1 to examine shift operators' response to the situation. Based on the review of the findings, a situation assessment model was developed to analyze shift operators' understanding on whether core cooling was successfully performed in Unit 1 through the operation of isolation condenser. It was found that lack of information could be one of the main causes for the failure in core cooling by the IC in Unit 1. It is also recommended that the differences in the mathematical model for the situation assessment and that of the real operator need to be further investigated.

Abbreviations [Annex to The Fukushima Daiichi Accident, Technical Volume 2/5

International Nuclear Information System (INIS)

2015-01-01

This annex is a list of abbreviations used in the publication The Fukushima Daiichi Accident, Technical Volume 2/5. The list includes the abbreviations for: • Agency for Natural Resources and Energy; • essential service water; • International Nuclear and Radiological Event Scale;• Integrated Regulatory Review Service; • Japan Atomic Energy Agency; • Japan Atomic Energy Commission; • Japan Power Engineering and Inspection Corp; • Japan Nuclear Energy Safety Organization; • low head safety injection; • low level radioactive waste; • Madras Atomic Power Station; • main control room; • Ministry of Economy, Trade and Industry; • Ministry of Education, Culture, Sports, Science and Technology; • Ministry of International Trade and Industry; • Ministry of Foreign Affairs; • Nuclear and Industrial Safety Agency; • Nuclear Power Corporation of India Limited; • nuclear power plant; • Nuclear Safety Commission; • Nuclear Power Engineering Corporation; • Nuclear Safety Technology Centre; • Onahama Port; • pressurized water reactor; • Science and Technology Agency; • Tokyo Electric Power Company

Electrical systems design applications on Japanese PWR plants in light of the Fukushima Daiichi Accident

International Nuclear Information System (INIS)

Nomoto, Tsutomu

2015-01-01

After the Fukushima Daiichi nuclear power plant (1F-NPP) accident (i.e. Station Blackout), several design enhancements have been incorporated or are under considering to Mitsubishi PWR plants' design of not only operational plants' design but also new plants' design. Especially, there are several important enhancements in the area of the electrical system design. In this presentation, design enhancements related to following electrical systems/equipment are introduced; - Offsite Power System; - Emergency Power Source; - Safety-related Battery; - Alternative AC Power Supply Systems. In addition, relevant design requirements/conditions which are or will be considered in Mitsubishi PWR plants are introduced. (authors)

Mobility of radioactive cesium in soil originated from the Fukushima Daiichi nuclear disaster. Application of extraction experiments

International Nuclear Information System (INIS)

Yoshikazu Kikawada; Takao Oi; Katsumi Hirose; Masaaki Hirose; Atsushi Tsukamoto; Ko Nakamachi; Teruyuki Honda; Hiroaki Takahashi

2015-01-01

Extraction experiments on soil radioactively contaminated by the Fukushima Daiichi Nuclear Power Plant accident were conducted by using a variety of extractants to acquire knowledge on the mobility of radioactive cesium in soil. The experimental results revealed that cesium is tightly bound with soil particles and that radioactive cesium newly deposited on soil due to the accident had apparently a higher mobility than stable cesium commonly existing in soil. The results suggested that radioactive cesium deposited on soil hardly migrates via aqueous processes, although chemical and mineralogical conditions of soil affect their mobility. (author)

Measurement of Iodine-129 in surface soil collected near the Fukushima Daiichi nuclear power plant accident site

International Nuclear Information System (INIS)

Miyake, Yasuto; Matsuzaki, Hiroyuki; Fujiwara, Takeshi; Saito, Takumi; Yamagata, Takeyasu; Honda, Maki

2013-01-01

Iodine-129 in soil around Fukushima Daiichi nuclear power plant were measured by Accelerator Mass Spectrometry and isotopic ratio of radioiodine was estimated. Surface deposition amount of Iodine-129 resulted in 6.7 to 5500 mBq/m"2. The mean isotopic ratio between Iodine-129 and Iodine-131 at the accident was estimated that "1"2"9"I"/"1"3"1I = 26±6 as of March 11 2011. This result was compared to the calculation result of ORIGEN2 code to test the validity of this estimation. (author)

Study on filling materials suitable for seawater piping trench closure work at Fukushima Daiichi Nuclear Power Plant

International Nuclear Information System (INIS)

Yanai, Shuji; Hibi, Yasuki; Nishikori, Kazumasa; Sato, Keita

2016-01-01

Highly contaminated water leaking from the reactor buildings and turbine buildings damaged by the 2011 Great East Japan Earthquake has accumulated in the seawater piping trenches of Fukushima Daiichi Nuclear Power Station Units 2, 3, and 4. In November 2014, work commenced to replace and remove this contaminated water by filling the trenches with filling materials, and this work was completed in December 2015. This paper summarizes the contents of this study on various filling materials, including special fillers with long-distance underwater flowability applied to the horizontal tunnel parts of the trenches. (author)

The second update of the Fukushima Daiichi Nuclear Station accident. June 1 through August 31, 2011

International Nuclear Information System (INIS)

Shibutani, Yu

2011-01-01

The Fukushima Daiichi accident occurred on March 11, 2011. The Japanese government and Tokyo Electric Power Company (TEPCO) encountered great deal of difficulties to stabilize the nuclear power reactor. Although the maximum radiation level has decreased, it still accounts for one-fifth of the level detected as of end of August 2011. There are currently growing concerns regarding the complexities of nuclear energy that are faced by the society of Japan. Owing to the occurrence of the Fukushima Daiichi accident, the firm belief on absolute safety of Japan's nuclear power plants has suddenly collapsed. Over the past decades, people tended to trust the government and electric power companies, which assured the safety and ensured about the necessity of nuclear power. However the recent disaster that took place in Fukushima has triggered public anger and distrusts that lead to negative campaigns against nuclear energy, in addition to oppositions against the government and nuclear power companies. The harsh public criticism has forced the government to separate the Nuclear and Industrial Safety Agency (NISA) from affiliation with the Ministry of Economy, Trade and Industry (METI). This action was taken since NISA had expressed contradictions with METI, which is the promoting agency for nuclear energy, The nation-wide opinion poll and surveys undertaken by Asahi Shimbun, a leading Japanese daily newspaper, has announced that 74% of respondents supported the policy to phase-out all nuclear power plants with the final goal to completely end the operation of nuclear plants. A mere 14% of the respondents disagree. There are approximately 100,000 or more residents that evacuated from the dangerous Fukushima Daiichi zone and were suffering from immediate threats such as radiation exposure, health problems, sanitary contamination, products shipment ban, business slump, groundless rumors, etc. These conditions have severely weakened their capability to completely recover and

Philosophy of safety assurance after the Fukushima Daiichi accident. From views of experts

International Nuclear Information System (INIS)

Hisada, Tsukasa

2014-01-01

Knowledge incorporating meetings were held to exchange views of experts in order to learn respective safety concept and philosophy of safety assurance except nuclear area, how should be prepared for beyond expectation and what was needed to build social credibility, and how to upgrade safety measures of nuclear power station after the Fukushima Daiichi accident. Meeting had been held twice a year since FY2012 and two lecturers were invited at each meeting to give a lecture on the specified theme such as safety assurance in aviation area and chemical plants, and 'safety target of engineering system'. Common or different views on safety assurance between nuclear and other areas were identified, and risk concept and sincere attitude of explaining engineer were mentioned quite important for preparation for beyond expectation and building social credibility. (T. Tanaka)

Research investigation report on Fukushima Daiichi nuclear accident

International Nuclear Information System (INIS)

2012-03-01

This report was issued in February 2012 by Rebuild Japan Initiative Foundation's Independent Investigation Commission on the Fukushima Daiichi Nuclear Accident, which consisted of six members from the private sector in independent positions and with no direct interest in the business of promoting nuclear power. Commission aimed to determine the truth behind the accident by clarifying the various problems and reveal systematic problems behind these issues so as to create a new starting point by identifying clear lessons learned. Report composed of four chapters; (1) progression of Fukushima accident and resulting damage (accident management after Fukushima accident, and effects and countermeasure of radioactive materials discharged into the environment), (2) response against Fukushima accident (emergency response of cabinet office against nuclear disaster, risk communication and on-site response against nuclear disaster), (3) analysis of historical and structural factors (technical philosophy of nuclear safety, problems of nuclear safety regulation of Fukushima accident, safety regulatory governance and social background of 'Safety Myth'), (4) Global Context (implication in nuclear security, Japan in nuclear safety regime, U.S.-Japan relations for response against Fukushima accident, lessons learned from Fukushima accident - aiming at creation of resilience). Report could identify causes of Fukushima accident and factors related to resulting damages, show the realities behind failure to prevent the spread of damage, and analyze the overall structural and historical background behind the accidents. (T. Tanaka)

Study of treatment scenarios for fuel debris removed from Fukushima Daiichi NPS

International Nuclear Information System (INIS)

Washiya, Tadahiro; Yano, Kimihiko; Kaji, Naoya; Yamada, Seiya; Kamiya, Masayoshi

2015-01-01

On March 11, 2011, a severe nuclear accident occurred at Tokyo Electric Power Company (TEPCO)’s Fukushima Daiichi Nuclear Power Plant (hereinafter called as F1). After the accident, the Council for the Decommissioning was established, mainly by the government and TEPCO, and a road map for the F1 decommissioning was drawn up. In the road map, the fuel debris removal from the reactors is scheduled to launch around 2020. In this study, the characteristics and technological issues of each potential treatment scenario were extracted, and the scenarios were prioritized in advance of formal evaluations in the future. The preliminary evaluation results show that long term storage and direct disposal have more positive aspects in terms of economic efficiency and radioactive waste generation. On the other hand, stabilizing processing, aqueous processing, and pyrochemical processing have been estimated to have more disadvantages in such aspects. (author)

Birth Outcomes after the Fukushima Daiichi Nuclear Power Plant Disaster: A Long-Term Retrospective Study.

Science.gov (United States)

Leppold, Claire; Nomura, Shuhei; Sawano, Toyoaki; Ozaki, Akihiko; Tsubokura, Masaharu; Hill, Sarah; Kanazawa, Yukio; Anbe, Hiroshi

2017-05-19

Changes in population birth outcomes, including increases in low birthweight or preterm births, have been documented after natural and manmade disasters. However, information is limited following the 2011 Fukushima Daiichi Nuclear Power Plant Disaster. In this study, we assessed whether there were long-term changes in birth outcomes post-disaster, compared to pre-disaster data, and whether residential area and food purchasing patterns, as proxy measurements of evacuation and radiation-related anxiety, were associated with post-disaster birth outcomes. Maternal and perinatal data were retrospectively collected for all live singleton births at a public hospital, located 23 km from the power plant, from 2008 to 2015. Proportions of low birthweight (effects on maternal and perinatal health.

Accident at the Fukushima Dai-ichi Nuclear Power Stations of TEPCO —Outline & lessons learned—

Science.gov (United States)

TANAKA, Shun-ichi

2012-01-01

The severe accident that broke out at Fukushima Dai-ichi nuclear power stations on March 11, 2011, caused seemingly infinite damage to the daily life of residents. Serious and wide-spread contamination of the environment occurred due to radioactive materials discharged from nuclear power stations (NPSs). At the same time, many issues were highlighted concerning countermeasures to severe nuclear accidents. The accident is outlined, and lessons learned are extracted with respect to the safety of NPSs, as well as radiation protection of residents under the emergency involving the accident. The materials of the current paper are those released by governmental agencies, academic societies, interim reports of committees under the government, and others. PMID:23138450

Accident at the Fukushima Dai-ichi nuclear power stations of TEPCO. Outline and lessons learned

International Nuclear Information System (INIS)

Tanaka, Shun-ichi

2012-01-01

The severe accident that broke out at Fukushima Dai-ichi nuclear power stations on March 11, 2011, caused seemingly infinite damage to the daily life of residents. Serious and wide-spread contamination of the environment occurred due to radioactive materials discharged from nuclear power stations (NPSs). At the same time, many issues were highlighted concerning countermeasures to severe nuclear accidents. The accident is outlined, and lessons learned are extracted with respect to the safety of NPSs, as well as radiation protection of residents under the emergency involving the accident. The materials of the current paper are those released by governmental agencies, academic societies, interim reports of committees under the government, and others. (author)

Regional long-term model of radioactivity dispersion and fate in the Northwestern Pacific and adjacent seas: application to the Fukushima Dai-ichi accident

International Nuclear Information System (INIS)

Maderich, V.; Bezhenar, R.; Heling, R.; With, G. de; Jung, K.T.; Myoung, J.G.; Cho, Y.-K.; Qiao, F.; Robertson, L.

2014-01-01

The compartment model POSEIDON-R was modified and applied to the Northwestern Pacific and adjacent seas to simulate the transport and fate of radioactivity in the period 1945–2010, and to perform a radiological assessment on the releases of radioactivity due to the Fukushima Dai-ichi accident for the period 2011–2040. The model predicts the dispersion of radioactivity in the water column and in sediments, the transfer of radionuclides throughout the marine food web, and subsequent doses to humans due to the consumption of marine products. A generic predictive dynamic food-chain model is used instead of the biological concentration factor (BCF) approach. The radionuclide uptake model for fish has as a central feature the accumulation of radionuclides in the target tissue. The three layer structure of the water column makes it possible to describe the vertical structure of radioactivity in deep waters. In total 175 compartments cover the Northwestern Pacific, the East China and Yellow Seas and the East/Japan Sea. The model was validated from 137 Cs data for the period 1945–2010. Calculated concentrations of 137 Cs in water, bottom sediments and marine organisms in the coastal compartment, before and after the accident, are in close agreement with measurements from the Japanese agencies. The agreement for water is achieved when an additional continuous flux of 3.6 TBq y −1 is used for underground leakage of contaminated water from the Fukushima Dai-ichi NPP, during the three years following the accident. The dynamic food web model predicts that due to the delay of the transfer throughout the food web, the concentration of 137 Cs for piscivorous fishes returns to background level only in 2016. For the year 2011, the calculated individual dose rate for Fukushima Prefecture due to consumption of fishery products is 3.6 μSv y −1 . Following the Fukushima Dai-ichi accident the collective dose due to ingestion of marine products for Japan increased in 2011 by a

New maintenance strategy of Tokyo Electric Power Company and Fukushima Dai-ichi Nuclear Power Plant for effective ageing management and safe long-term operation

International Nuclear Information System (INIS)

Inagaki, Takeyuki; Yamashita, Norimichi

2009-01-01

Fukushima Dai-ichi Nuclear Power Plant is the oldest among three nuclear power plants owned and operated by Tokyo Electric Power Company, which consists of six boiling water reactor units. The commercial operation of Unit 1 was commenced in 1971 (37 years old) and Unit 6 in 1978 (29 years old). Currently ageing degradations of systems, structures and components are managed through maintenance programs, component replacement/refurbishment programs and long-term maintenance plans. The long-term maintenance plans are established through ageing management component replacement/refurbishment programs reviews performed before the 30th year of operation and they are for safe and reliable operation after 30 years (long-term operation). However the past maintenance actions and past component replacement/refurbishment programs were not always proactive and past operational experience and maintenance practices suggest that effective/proactive ageing management programs be introduced in earlier stage of the plant operation. In this circumstance, Tokyo Electric Power Company and Fukushima Dai-ichi Nuclear Power Plant are setting up a new maintenance strategy that includes 1) improving the normal maintenance programs by using ageing degradation data, 2) effective use of information on internal/external operational experience and maintenance practices related to ageing, and 3) proactive component/equipment refurbishment programs during a refreshment outage for safe and reliable long-term operation. To accomplish the goal of this strategy, strengthening engineering capability of plant staff members is a crucial required for the plant. The objective of this paper is to briefly explain main results ageing management reviews, past and current significant ageing issues and management programs against them, and the new maintenance strategy established by Tokyo Electric Power Company and Fukushima Dai-ichi Nuclear Power Plant. (author)

Industrial Safety and Utopia: Insights from the Fukushima Daiichi Accident.

Science.gov (United States)

Travadel, Sébastien; Guarnieri, Franck; Portelli, Aurélien

2018-01-01

Feedback from industrial accidents is provided by various state or even international, institutions, and lessons learned can be controversial. However, there has been little research into organizational learning at the international level. This article helps to fill the gap through an in-depth review of official reports of the Fukushima Daiichi accident published shortly after the event. We present a new method to analyze the arguments contained in these voluminous documents. Taking an intertextual perspective, the method focuses on the accident narratives, their rationale, and links between "facts," "causes," and "recommendations." The aim is to evaluate how the findings of the various reports are consistent with (or contradict) "institutionalized knowledge," and identify the social representations that underpin them. We find that although the scientific controversy surrounding the results of the various inquiries reflects different ethical perspectives, they are integrated into the same utopian ideal. The involvement of multiple actors in this controversy raises questions about the public construction of epistemic authority, and we highlight the special status given to the International Atomic Energy Agency in this regard. © 2017 The Authors Risk Analysis published by Wiley Periodicals, Inc. on behalf of Society for Risk Analysis.

Analysis of the accident at Fukushima Daiichi nuclear power plant in an A BWR reactor; Analisis del accidente de la planta nucleoelectrica de Fukushima Daiichi en un reactor tipo ABWR

Energy Technology Data Exchange (ETDEWEB)

Escorcia O, D. [UNAM, Facultad de Ingenieria, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Salazar S, E., E-mail: daniel.escorcia.ortiz@gmail.com [UNAM, Facultad de Ingenieria, Laboratorio de Analisis en Ingenieria de Reactores Nucleares, 62250 Jiutepec, Morelos (Mexico)

2016-09-15

The present work aims to recreate the accident occurred at the Fukushima Daiichi nuclear power plant in Japan on March 11, 2011, making use of an academic simulator of forced circulation of the A BWR reactor provided by the IAEA to know the scope of this simulator. The simulator was developed and distributed by the IAEA for academic purposes and contains the characteristics and general elements of this reactor to be able to simulate transients and failures of different types, allowing also to observe the general behavior of the reactor, as well as several phenomena and present systems in the same. Is an educational tool of great value, but it does not have a scope that allows the training of plant operators. To recreate the conditions of the Fukushima accident in the simulator, we first have to know what events led to this accident, as well as the actions taken by operators and managers to reduce the consequences of this accident; and the sequence of events that occurred during the course of the accident. Differences in the nuclear power plant behavior are observed and interpreted throughout the simulation, since the Fukushima plant technology and the simulator technology are not the same, although they have several elements in common. The Fukushima plant had an event that by far exceeded the design basis, which triggered in an accident that occurred in the first place by a total loss of power supply, followed by the loss of cooling systems, causing a level too high in temperature, melting the core and damaging the containment accordingly, allowing the escape of hydrogen and radioactive material. As a result of the simulation, was determined that the scope of the IAEA academic simulator reaches the entrance of the emergency equipment, so is able to simulate almost all the events occurred at the time of the earthquake and the arrival of the tsunami in the nuclear power plant of Fukushima Daiichi. However, due to its characteristics, is not able to simulate later

Crystal Structure of a Monomeric Form of Severe Acute Respiratory Syndrome Coronavirus Endonuclease Nsp15 Suggests a Role for Hexamerization As An Allosteric Switch

Energy Technology Data Exchange (ETDEWEB)

Joseph, J.S.; Saikatendu, K.S.; Subramanian, V.; Neuman, B.W.; Buchmeier, M.J.; Stevens, R.C.; Kuhn, P.; /Scripps Res. Inst.

2007-07-09

Mature nonstructural protein-15 (nsp15) from the severe acute respiratory syndrome coronavirus (SARS-CoV) contains a novel uridylate-specific Mn{sup 2+}-dependent endoribonuclease (NendoU). Structure studies of the full-length form of the obligate hexameric enzyme from two CoVs, SARS-CoV and murine hepatitis virus, and its monomeric homologue, XendoU from Xenopus laevis, combined with mutagenesis studies have implicated several residues in enzymatic activity and the N-terminal domain as the major determinant of hexamerization. However, the tight link between hexamerization and enzyme activity in NendoUs has remained an enigma. Here, we report the structure of a trimmed, monomeric form of SARS-CoV nsp15 (residues 28 to 335) determined to a resolution of 2.9 Angstroms. The catalytic loop (residues 234 to 249) with its two reactive histidines (His 234 and His 249) is dramatically flipped by {approx}120 degrees into the active site cleft. Furthermore, the catalytic nucleophile Lys 289 points in a diametrically opposite direction, a consequence of an outward displacement of the supporting loop (residues 276 to 295). In the full-length hexameric forms, these two loops are packed against each other and are stabilized by intimate intersubunit interactions. Our results support the hypothesis that absence of an adjacent monomer due to deletion of the hexamerization domain is the most likely cause for disruption of the active site, offering a structural basis for why only the hexameric form of this enzyme is active.

Evacuation after the Fukushima Daiichi Nuclear Power Plant Accident Is a Cause of Diabetes: Results from the Fukushima Health Management Survey

Directory of Open Access Journals (Sweden)

Hiroaki Satoh

2015-01-01

Full Text Available The Great East Japan Earthquake and Fukushima Daiichi nuclear disaster in 2011 forced the evacuation of a large number of residents and created changes in the lifestyle of the evacuees. These changes may have affected the evacuees’ glucose metabolism, thereby leading to an increase in the incidence of diabetes. This study included Japanese men and women who were living near the Fukushima Daiichi Nuclear Power Plant in Fukushima prefecture before the disaster. Subjects subsequently underwent annual health checkups with a focus on metabolic syndromes, which were conducted under the Health Care Insurers. Using the Comprehensive Health Check survey, we analyzed changes in the glucose metabolism before and after the disaster. A total of 27,486 subjects underwent follow-up examinations after the disaster, with a mean follow-up period of 1.6 years. After the disaster, the prevalence of diabetes increased significantly, and we observed that the incidence of diabetes was significantly greater among evacuees than among nonevacuees. Furthermore, multivariate logistic regression analysis revealed that evacuation was significantly associated with the incidence of diabetes. In conclusion, this is the first study to demonstrate that evacuation is associated with the incidence of diabetes. This information may be used to guide follow-up recommendations for evacuees.

Evaluation of averted doses to members of the Public by tap water restrictions after the Fukushima Daiichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Kinase, Sakae; Kimura, Masanori; Hato, Shinji

2014-01-01

The effectiveness of urgent protective measures such as tap water restrictions and bottled water supplies in the early stage of an emergency exposure situation was studied after the Fukushima Daiichi nuclear power plant accident. Temporal changes in the concentration of an important radionuclide –iodine 131– in tap water were analyzed using published data in Fukushima, Ibaraki and Tokyo. Averted doses to members of the public due to chronic intakes of iodine 131 through tap water restrictions were also evaluated using an internal dose calculation code, DSYS-chronic code. In addition, the costs of bottled water supplies were calculated approximately. Consequently, it was found that the apparent half-life of iodine 131 in tap water was 2.8±1.2 days. The averted equivalent doses to the thyroid of members of the public –1-year-old children– were found to have a maximum value of 8.2 mSv in a local area of Fukushima. In comparison with Fukushima, the bottled water supplies might be a large sum of money regardless of the low doses in Tokyo. In conclusion, apart from the bottled water supplies, the tap water restrictions implemented by the authorities would be effective after the Fukushima Daiichi nuclear power plant accident. (author)

Analysis of core melt accident in Fukushima Daiichi-Unit 1 nuclear reactor

International Nuclear Information System (INIS)

Tanabe, Fumiya

2011-01-01

In order to obtain a profound understanding of the serious situation in Unit 1 and Unit 2/3 reactors of Fukushima Daiichi Nuclear Power Station (hereafter abbreviated as 1F1 and 1F2/3, respectively), which was directly caused by tsunami due to a huge earthquake on 11 March 2011, analyses of severe core damage are performed. In the present report, the analysis method and 1F1 analysis are described. The analysis is essentially based on the total energy balance in the core. In the analysis, the total energy vs. temperature curve is developed for each reactor, which is based on the estimated core materials inventory and material property data. Temperature and melt fraction are estimated by comparing the total energy curve with the total stored energy in the core material. The heat source is the decay heat of fission products and actinides together with reaction heat from the zirconium steam reaction. (author)

The Fukushima Dai-ichi Accident and its implications for the safety of nuclear power

Science.gov (United States)

Barletta, William

2016-05-01

Five years ago the dramatic events in Fukushima that followed the massive earthquake and subsequent tsunami that struck Japan on March 11, 2011 sharpened the focus of scientists, engineers and general public on the broad range of technical, environmental and societal issues involved in assuring the safety of the world's nuclear power complex. They also called into question the potential of nuclear power to provide a growing, sustainable resource of CO2-free energy. The issues raised by Fukushima Dai-ichi have provoked urgent concern, not only because of the potential harm that could result from severe accidents or from intentional damage to nuclear reactors or to facilities involved in the nuclear fuel cycle, but also because of the extensive economic impact of those accidents and of the measures taken to avoid them.

Spatial distribution of Iodine-129 in surface soil around the Fukushima Daiichi Nuclear Power Plant

International Nuclear Information System (INIS)

Miyake, Yasuto; Tagi, Kazuhiro; Matsuzaki, Hiroyuki; Fujiwara, Takeshi; Saito, Takumi; Yamagata, Takeyasu; Tsuchiya, Yoko; Nakano, Chuichiro; Honda, Maki

2011-01-01

Due to the accident at the Fukushima Daiichi nuclear power plant, which was caused by the Great East Japan Earthquake, a lot of radioactive materials were released into the environment. Among them, Iodine-131, which has a short half-life of 8 days, is thought to be hardly detected after the accident is concluded. It is very important to research how leaked out Iodine-131 was diffused in order to estimate the health impact of radiation at the time of the accident. On the other hand, Iodine-129, which was leaked out and was thought to act chemically-identically as Iodine-131, has an extremely long half-life of 15.7 million years and we are able to measure it equally after the accident. By following the trail of Iodine-129, it is considered to estimate the distribution of Iodine-131. To do this, at first, it is essential to measure simultaneously Iodine-131 and Iodine-129 in the same sample picked from near-the Fukushima Daiichi nuclear power plant and examine the relation between them (for example, the isotopic ratio of Iodine derived from the nuclear power plant (I-129/I-131)). At this study, we measured Iodine-129 in surface soil within 60 kilometers of the Fukushima Daiichi nuclear power plant, which was picked by research team of Nuclear Engineering Research Laboratory, Faculty of Engineering, the University of Tokyo. We discuss Iodine-129 derived from the nuclear power plant by considering the concentration range, the relation of a distance or a direction from the nuclear power plant, and the relation between I-129 and other radioactive nuclides (Cs-134, Cs-137, I-131). Since Iodine-129, which had been leaked out from the nuclear fuel reprocessing plant in Europe, was already transferred to Japan by way of the atmospheric transportation before the accident, it is important to distinguish between Iodine-129 from this accident and from the reprocessing plant. Then, we want to obtain the I-129/I-131 ratio originating in the accident precisely and discuss the

Review of health issues of workers engaged in operations related to the accident at the Fukushima Daiichi Nuclear Power Plant.

Science.gov (United States)

Hiraoka, Koh; Tateishi, Seiichiro; Mori, Koji

2015-01-01

The aim of this review was to summarize the lessons learned from the experience in protecting the health of workers engaged in operations following the accident at the Fukushima Daiichi Nuclear Power Plant (NPP). We reviewed all types of scientific papers examining workers' health found in Medline and Web of Sciences as well as some official reports published by the Ministry of Health, Labour and Welfare of Japan and other governmental institutes. The papers and reports were classified into those investigating workers at the Fukushima Daiichi and Daini NPPs, workers engaged in decontamination operations in designated areas, and other workers. Regarding workers at the NPPs, many efforts were made to establish an emergency-care and occupational health system. Risk management efforts were undertaken for radiation exposure, heat stress, psychological stress, outbreak of infectious diseases, and fitness for work. Only a few reports dealt with decontamination workers and others; however, the health management of these workers was clearly weaker than that for workers at the NPPs. Many lessons can be learned from what occurred. That knowledge can be applied to ongoing decommissioning work and to future disasters. In addition, it is necessary to study the long-term health effects of radiation exposure and to accumulate data about the health of workers engaged in decontamination work and other areas.

MDEP Design-Specific Common Position CP-ABWRWG-01. Common position addressing issues related to the Fukushima Daiichi nuclear power plant accident

International Nuclear Information System (INIS)

2016-01-01

On 11 March 2011 Japan suffered its worst recorded earthquake. The epicentre was 110 miles (180 km) east north east from TEPCO's Fukushima Daiichi NPP which had 6 operating Boiling Water Reactors (BWR). Reactor Units 1, 2 and 3 on this site were operating at power before the event and on detection of the earthquake shut down safely. Reactor Unit 4 was not loaded with any fuel assemblies due to maintenance, including replacement of the core shroud. Reactor Units 5 and 6 were shut down for maintenance. Initially, on-site back-up diesel generators were used to provide the alternating current (AC) electrical supplies to power essential post-trip cooling systems. Within an hour a massive tsunami from the earthquake inundated the site; all AC electrical power to the cooling systems for the reactor and reactor fuel pools was lost, including that from all but one (in Unit 6) back-up diesel generators, as well as a significant amount of direct current (DC) supplies and essential instrumentation. Over the next few hours, and days, the fuel in Reactor Units 1, 2 and 3 heated up and degraded. There were hydrogen explosions which caused considerable damage to the reactor buildings in Units 1, 3 and 4. For over a week the site struggled to put cooling water into the reactors and the reactor fuel pools, by using means untried before and/or unplanned. Electrical supplies were gradually reconnected to the reactor buildings and a degree of control returned. Heavily contaminated water, used to cool the reactors and spent fuel pools, collected in un-contained areas of the site and leaked out to sea. There were also significant releases of radioactivity to the air. However, to date, the indications are that the public health effects from radiation exposure are not significant. This was a serious nuclear accident, with an International Nuclear and Radiological Event Scale (INES) rating of Level 7 (the highest level). Tens of thousands of people were evacuated from a zone extending

Mental health problems after the 2011 Fukushima Dai-ichi nuclear power plant accident

International Nuclear Information System (INIS)

Niwa, Shin-ichi

2012-01-01

The name of Fukushima has now become well-known worldwide after Hiroshima and Nagasaki as the third place exposed to radiation in Japan. This radiation pollution has severely damaged the chief industries of Fukushima Prefecture, namely agriculture, fishery, and tourist industry. It has also stimulated strong anxious feelings among parents with young children. The accident has caused a critical situation in the psychiatric and mental health services in Fukushima as well. Five hospitals with psychiatric beds within 30 km from the Fukushima Dai-ichi Nuclear Power Plant were ordered to transfer their inpatients to other hospitals outside the designated 30 km-areas and to close down the hospitals immediately after the nuclear plant accident. In total, more than 800 psychiatric beds disappeared in an instant, and 1,228 persons including psychiatric inpatients and residents of elderly people nursing homes were transferred to other facilities far away. Rational explanation that low-level radiation in Fukushima will not do harm to people did not necessarily relieve existing anxiety among people. The terms 'safety' and 'relief' are usually used in combination; however, 'relief' was separated from 'safety' this time in Fukushima. People gradually began to feel 'relieved', when they themselves got involved in the cleaning work of radiation although its effect remained ambiguous. Now we have the following mental health problems after the 2011 Fukushima Dai-ichi nuclear power plant accident; recovery and maintenance of treatment systems for psychiatric patients in the affected areas, efforts for early detection and intervention of depression, severe stress disorder, adaptation disorder, and alcohol abuse which are expected to occur due to the earthquake and radiation pollution, prevention of suicides, relief from anxiety resulting from radiation pollution, adequate treatment of mental problems among children with long-term evacuation, prevention of fall in physical and mental

The Fukushima Daiichi nuclear site. Airborne releases during works on unit 3 in August 2013

International Nuclear Information System (INIS)

2014-07-01

After having briefly recalled the consequences of the earthquake and tsunami on the Fukushima-Daiichi nuclear power station, this document briefly describes what happened to the building of the reactor number 3, and works to be done to dismantle this installation: removal of damaged structures, of debris in the pool, and then removal of fuel from this pool, removal of the core degraded fuel. The removal of structures and debris has been achieved in October 2013, but leaded to radioactive airborne releases. Simulations of atmospheric dispersion have been performed by the IRSN. Radioactive measurements have been also performed, and the evolution of crop contamination between 2011 and 2013 is discussed, notably in the case of rice. Lessons learned can be useful for the dismantling of other units

Time changes in radiocesium wash-off from various land uses after the Fukushima Daiichi NPP accident

Science.gov (United States)

Onda, Yuichi; Kato, Hiroaki; Yoshimura, Kazuya; Tsujimura, Maki; Wakiyama, Yoshifumi; Taniguchi, Keisuke; Sakaguchi, Aya; Yamamoto, Masayoshi

2014-05-01

A number of studies have been conducted to monitor and model the time series change of radiocesium transfer through aquatic systems after significant fallout, especially from the Chernobyl disaster. However, no data is available for the temporal changes of radiocesium concentration in environmental materials such as soil and water after the Fukushima Daiichi nuclear power plant accident. Our research team has been monitoring the environmental consequences of radioactive contamination just after the Fukushima Daiichi NPP accident in Yamakiya-district, Kawamata town, Fukushima prefecture. Research items are listed below. 1. Radiocesium wash-off from the runoff-erosion plot under different land use. 2. Measurement of radiocesium transfer in forest environment, in association with hydrological pathways such as throughfall and overlandflow on hillslope. 3. Monitoring on radiocesium concentration in soil water, ground water, and spring water. 4. Monitoring of dissolved and particulate radiocesium concentration in river water, and stream water from the forested catchment. 5.Measurement of radiocesium content in drain water and suspended sediment from paddy field. Our monitoring result demonstrated that the Cs-137 concentration in eroded sediment from the runoff-erosion plot has been almost constant for the past 3 years, however the Cs-137 concentration of suspended sediment from the forested catchment showed slight decrease through time. On the other hand, the suspended sediment from paddy field and those in river water from large catchments exhibited rapid decrease in Cs-137 concentration with time. The decreasing trend of Cs-137 concentration were fitted by the two-component exponential model, differences in decreasing rate of the model were compared and discussed among various land uses and catchment scales. Such analysis can provide important insights into the future prediction of the radiocesium wash-off from catchments with different land uses.

Sociological aspects of 3.11 Fukushima Daiichi Accident aftermath and the Genshiryoku-mura (nuclear village, or pro-nuclear concession sector)

Energy Technology Data Exchange (ETDEWEB)

Sawada, T., E-mail: tetsuo@nr.titech.ac.jp [Tokyo Inst. of Technology, Research Laboratory for Nuclear Reactors, Meguro-ku, Tokyo (Japan)

2014-07-01

In the 3.11 Fukushima Daiichi Accident aftermath, information contamination induced societal confusion that led to unnecessarily grave fear among the public. The origins and development of the information contamination, and the labeling of Goyo-gakusha and Genshiryoku-mura were phenomenologically analyzed. The historical background to, and reasons for emergence of Goyo-gakusha's were examined by using an axiological approach. The analyses and examination have clarified a typical case of the origins to formation of Genshiryoku-mura. (author)

Five Years after the Fukushima Daiichi Accident: Nuclear Safety Improvements and Lessons Learnt

International Nuclear Information System (INIS)

Magwood, William D. IV; Niel, Jean-Christophe; Fuketa, Toyoshi; Sheron, Brian; Boyd, Michael; McGarry, Ann; Dussart-Desart, Roland; Reig, Javier; Hah, Yeonhee; Nieh, Ho; Vasquez-Maignan, Ximena; Salgado, Nancy; White, Andrew; Lazo, Edward; Creswell, Len; Leeds, Eric; Gannon-Picot, Cynthia; Griffiths, Janice

2016-01-01

Countries around the world continue to implement safety improvements and corrective actions based on lessons learnt from the 11 March 2011 accident at the Fukushima Daiichi nuclear power plant. This report provides a high-level summary and update on these activities, and outlines further lessons learnt and challenges identified for future consideration. It focuses on actions taken by NEA committees and NEA member countries, and as such is complementary to reports produced by other international organisations. It is in a spirit of openness and transparency that NEA member countries share this information to illustrate that appropriate actions are being taken to maintain and enhance the level of safety at their nuclear facilities. Nuclear power plants are safer today because of these actions. High-priority follow-on items identified by NEA committees are provided to assist countries in continuously benchmarking and improving their nuclear safety practices. (authors)

Provisional English Translation by the IAEA of Notification Faxes Sent by the Fukushima Daiichi NPP Site Superintendent to Off-Site Officials on 11 March 2011. Annex I of Technical Volume 3

International Nuclear Information System (INIS)

2015-01-01

This annex contains a provisional English translation of the faxes sent by the Fukushima Daiichi NPP Site Superintendent to METI, the Governor of Fukushima Prefecture and the Mayors of Okuma and Futaba on 11 March 2011

Environmental remediation following the Fukushima-Daiichi accident

Energy Technology Data Exchange (ETDEWEB)

Tagawa, A.; Miyahara, K.; Nakayama, S. [Japan Atomic Energy Agency - JAEA, 4-49 Muramatsu, Tokai-mura, Naka-gun, Ibaraki 319-1184 (Japan)

2013-07-01

A wide area of Fukushima Prefecture was contaminated with radioactivity released by the Fukushima Daiichi nuclear accident. The decontamination pilot projects conducted by JAEA aimed at demonstrating the applicability of different techniques to rehabilitate affected areas. As most radioactive cesium is concentrated at the top of the soil column and strongly bound to mineral surfaces, there are 3 options left to decrease the gamma dose rate (usually measured 1 m above the ground surface): the stripping of the contaminated topsoil (i.e. direct removal of cesium), the dilution by mixing and the soil profile inversion. The last two options do not generate waste. As the half-distance of {sup 137}Cs gammas in soil is in the order of 5-6 cm (depending on density and water content), the shielding by 50 cm of uncontaminated deep soil would theoretically reduce gamma doses by about 3 orders of magnitude. Which option is employed depends basically on the Cesium concentration in the topsoil, averaged over a 15-cm thickness. The JAEA's decontamination pilot projects focus on soil profile inversion and topsoil stripping. Two different techniques have been tested for the soil profile inversion: one is the reversal tillage by which surface soil of thickness of several tens of cm is reversed by using a tractor plough and the other is the complete interchanging of contaminated topsoil with uncontaminated subsoil by using a back-hoe. Reversal tillage with a tractor plough cost about 30 yen/m{sup 2}, which is an order of magnitude lower than that of topsoil-subsoil interchange (about 300 yen/m{sup 2}). Topsoil stripping is significantly more costly (between 550 yen/m{sup 2} and 690 yen/m{sup 2} according to the equipment used)

Public opinion on Fukushima Daiichi nuclear disaster

International Nuclear Information System (INIS)

Hirose, Hirotada

2013-01-01

This article showed trend of public opinion on nuclear power after Fukushima Daiichi nuclear disaster, for which the survey had been done five times under the same method and inquiries. Most unreliable source of information at disaster was government ministries and offices, whose unreliability sharply increased from 20% to about 50% after 3 months later and one year later after March 11 and reliability after 2 year and 5 months later (August 2013) was not high and almost comparable with unreliability of 27%. Nuclear disaster was most serious cause of Great East Japan earthquake disaster (60%) and not entirely ended due to such increase of contaminated water. Public opinion survey in August 2013 showed nuclear power stoppage totaled about 80% with immediate of about 30% and phaseout of about 50%, and possibility of occurrence of another nuclear accident comparable with Fukushima disaster was almost 80% with a belief not only earthquakes, tsunamis, terrorism but also human errors might initiate nuclear disaster if nuclear power restarted. Future most serious disaster would be earthquake (50%) and nuclear disaster (35%). Nuclear accident preparedness of government and local government was not enough (58% and 24%) and nothing (33% and 24%). Residents within UPZ (Urgent Protection action Planning Zone) of 30 km radius could not evacuate safely (57%) and entirely (22%). If government and local government encouraged damaged residents to come home with declaration of safety for evacuation area of nuclear accident, damaged residents might not return almost (46%) and entirely (9%). Notwithstanding people's strong feeling against nuclear power, LDP (Liberal Democratic Party) promoting nuclear power won an overwhelming victory at the election of House of Councilors in July 2013. Public opinion survey in August 2013 showed most important issue of voters was party's image (25%), economic measures (20%) and candidate's personality (13%), and nuclear power policy was only 5%. (T

Examination of a measuring method for judging the influence of fallout released by the accident of the Fukushima Dai-ichi NPS

Energy Technology Data Exchange (ETDEWEB)

Onishi, Yuko; Yoshii, Taiki; Kawasaki, Satoru [Japan Nuclear Energy Safety Organization, Nulcear Fuel Cycle and Radioactive Waste Management Safety Dept., Tokyo (Japan)

2012-07-15

Radioactive nuclides were released in the atmosphere by the accident of TEPCO's Fukushima Dai-ichi Nuclear Power Station in March, 2011, and they are detected on the materials that had no artificial radioactive nuclides before the accident. Confronted with this situation, NISA issued a guideline titled 'A guideline regarding treatment of materials in nuclear facilities considering the influence of fallout released from the accident of TEPCO's Fukushima Dai-ichi Nuclear Power Station' on March 30, 2012. The guideline shows that after judging whether there is the influence of fallout or not, the conventional clearance and NR systems can be used when there is no influence of fallout. On the other hand, the special treatment is required when it is judged that there is the influence. This report describes that a specific example of measuring method of the surface contamination of the materials for the judgment of the influence of fallout. 'The precautionary measurement' defined in NR system is useful for the judgment of the influence of fallout. The criterion of the judgment is the theoretical detection limit. Sampling points for the measurement should be selected depending on expected contamination status of the survey target, considering the site area, the states of facilities or equipments and airflow from outside of the facilities. Sampling number for the fallout should be greater than equal to 10. (author)

Examination of a measuring method for judging the influence of fallout released by the accident of the Fukushima Dai-ichi NPS

International Nuclear Information System (INIS)

Onishi, Yuko; Yoshii, Taiki; Kawasaki, Satoru

2012-07-01

Radioactive nuclides were released in the atmosphere by the accident of TEPCO's Fukushima Dai-ichi Nuclear Power Station in March, 2011, and they are detected on the materials that had no artificial radioactive nuclides before the accident. Confronted with this situation, NISA issued a guideline titled 'A guideline regarding treatment of materials in nuclear facilities considering the influence of fallout released from the accident of TEPCO's Fukushima Dai-ichi Nuclear Power Station' on March 30, 2012. The guideline shows that after judging whether there is the influence of fallout or not, the conventional clearance and NR systems can be used when there is no influence of fallout. On the other hand, the special treatment is required when it is judged that there is the influence. This report describes that a specific example of measuring method of the surface contamination of the materials for the judgment of the influence of fallout. 'The precautionary measurement' defined in NR system is useful for the judgment of the influence of fallout. The criterion of the judgment is the theoretical detection limit. Sampling points for the measurement should be selected depending on expected contamination status of the survey target, considering the site area, the states of facilities or equipments and airflow from outside of the facilities. Sampling number for the fallout should be greater than equal to 10. (author)

Update on the SDTP Sponsored Fukushima Daiichi Related Assesment Activities

International Nuclear Information System (INIS)

Allison, Chris

2014-01-01

Following the accident at Fukushima Daiichi, Innovative Systems Software and several other members of an international software development and training group (SDTP) started an assessment of the possible core/vessel damage states of Units 1-3. This assessment, using a reference RELAP/SCDAPSIM Laguna Verde BWR model developed by CNSNS, the Mexican nuclear regulatory body, was presented initially to the IAEA emergency response team for Fukushima in March of 2011. Our assessment for the IAEA indicated that significant fuel melting, fuel slumping, and lower head failure was likely for Units 1 and 3. The results for Unit 2 were inconclusive because of the complex thermal hydraulic conditions at the time of likely fuel melting. Since that time the SDTP related assessment activities have continued on three main fronts: (a) continued analysis using our representative Laguna Verde model to determine the likely failure modes leading to an un-intentional depressurization of the vessel during a SBO in a BWR, (b) development of improved RELAP/SCDAPSIM models to treat the likely mode of lower core support structure melting and failure, and (c) design studies for proposed fuel melting and relocation experiments in Japan to support model development and cleanup related activities, The presentation gives a brief summary and discussion of these activities.

Nuclear accidents at the Fukushima Dai-ichi power plant. History, events and consequences

International Nuclear Information System (INIS)

Berniolles, Jean Marc

2011-01-01

Written few weeks after the accident, this article first recalls the circumstances (earthquake and tsunami), and then describes the accidental process within the primary vessels of the Fukushima Dai-ichi number 1, 2 and 3 reactors. The author then describes the interventions which aimed at cooling these three reactors, the problem faced for the storage of used fuels, and then the sequence of accidents: loss of cooling means leading to an explosion, problems faced in the different storage pools. He describes the various steps of recovery (primary cooling, electricity supply), discusses the consequences in terms of radioactivity releases in the plant environment with a comparison with Chernobyl, and also in terms of nature and quantity of radioactive elements. He comments radioactivity controls and measurements, evacuation measures, measurements performed by the IAEA, measurements of sea radioactivity, and the establishment of maps of ground radioactivity around the plant. He discusses the perspectives associated with these measurements for the surroundings of the Fukushima site

Tritium in Japanese precipitation following the March 2011 Fukushima Daiichi Nuclear Plant accident.

Science.gov (United States)

Matsumoto, Takuya; Maruoka, Teruyuki; Shimoda, Gen; Obata, Hajime; Kagi, Hiroyuki; Suzuki, Katsuhiko; Yamamoto, Koshi; Mitsuguchi, Takehiro; Hagino, Kyoko; Tomioka, Naotaka; Sambandam, Chinmaya; Brummer, Daniela; Klaus, Philipp Martin; Aggarwal, Pradeep

2013-02-15

Tritium concentrations in Japanese precipitation samples collected after the March 2011 accident at the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) were measured. Values exceeding the pre-accident background were detected at three out of seven localities (Tsukuba, Kashiwa and Hongo) southwest of the FNPP1 at distances varying between 170 and 220 km from the source. The highest tritium content was found in the first rainfall in Tsukuba after the accident; however concentrations were 500 times less than the regulatory limit for tritium in drinking water. Tritium concentrations decreased steadily and rapidly with time, becoming indistinguishable from the pre-accident values within five weeks. The atmospheric tritium activities in the vicinity of the FNPP1 during the earliest stage of the accident was estimated to be 1.5×10(3) Bq/m(3), which is potentially capable of producing rainwater exceeding the regulatory limit, but only in the immediate vicinity of the source. Copyright © 2012 Elsevier B.V. All rights reserved.

Fukushima Daiichi Unit 1 Uncertainty Analysis-Exploration of Core Melt Progression Uncertain Parameters-Volume II.

Energy Technology Data Exchange (ETDEWEB)

Denman, Matthew R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brooks, Dusty Marie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-08-01

Sandia National Laboratories (SNL) has conducted an uncertainty analysi s (UA) on the Fukushima Daiichi unit (1F1) accident progression wit h the MELCOR code. Volume I of the 1F1 UA discusses the physical modeling details and time history results of the UA. Volume II of the 1F1 UA discusses the statistical viewpoint. The model used was developed for a previous accident reconstruction investigation jointly sponsored by the US Department of Energy (DOE) and Nuclear Regulatory Commission (NRC). The goal of this work was to perform a focused evaluation of uncertainty in core damage progression behavior and its effect on key figures - of - merit (e.g., hydrogen production, fraction of intact fuel, vessel lower head failure) and in doing so assess the applicability of traditional sensitivity analysis techniques .

The effects of the nuclear disaster at Fukushima Daiichi Nuclear Power Station on local governments

International Nuclear Information System (INIS)

Nakamura, Makoto; Dake, Kinji

2012-01-01

All Japan council of local governments with atomic power stations consisted of 24 reactor site and 6 neighboring local governments to solve reactor site related problems. Nuclear disaster at Fukushima Daiichi Nuclear Power Station affected member local governments to be forced in severe conditions such as 'removal of administrative function' or 'refuge over a wide district beyond local government area', not imagined before. The council set up working group for thirteen local governments themselves to investigate this disaster and find safety and prevention of disaster measures to be deployed in nuclear administration, which published report in March 2012. This article described outline of investigation and derived problems and direction of their solution. Main items were related with communication, resident evacuation, prevention of disaster system, and management of refuge site. (T. Tanaka)

Research and Activities of OECD/NEA Benchmark Study of the Accident at the Fukushima Daiichi Nuclear Power Station (BSAF) Project

Energy Technology Data Exchange (ETDEWEB)

Kim, Sung Il; Ha, Kwang Soon; Song, JinHo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

The severe accident codes were used to analysis the Fukushima Daiichi accident and give valuable information. In addition, the insufficient part of the code could be revised by comparing the calculation result with the measured data. In this circumstance, working plans have been set up to conduct a Benchmark Study of the Accident progression for the Fukushima Daiichi nuclear power plant(BSAF) units 1-3 with the members of the OECD/NEA. The BSAF project was launched in November 2012 with the fifteen organizations of eight countries (France, Germany, Korea, Russia, Spain, Switzerland, the United States, and Japan). The objectives of the project are: - to analyze the Fukushima accident progression. - to raise the understanding of severe accident(SA) phenomena. - to contribute the improvement of methods and models of SA code. - to contribute the status of debris distribution to a future debris removal plan. BSAF phase 2 also has been implemented from April, 2015 and it will be continued to March, 2018. It is more focused on the fission product behavior and source term estimation in phase 2. The phase 2 project implementation period is 3 years from April 2015 to March 2018. The main topic of the BSAF 2 is the fission product behavior in the Fukushima nuclear power plant. In the process of calculation, it is important to know the insufficient models in the code. Furthermore, the model would be applied to the KAERI's severe accident code after making up for the insufficient part.

Questions concerning safety and risk after the nuclear accidents in Japan. Deepened accident analysis for the Fukushima Daiichi power plant; Sicherheits- und Risikofragen im Nachgang zu den nuklearen Stoer- und Unfaellen in Japan. Vertiefte Ereignisanalyse zur Anlage Fukushima-Daini

Energy Technology Data Exchange (ETDEWEB)

Pistner, Christoph; Englert, Matthias [Oeko-Institut e.V. - Institut fuer Angewandte Oekologie, Darmstadt (Germany)

2015-02-25

The study questions concerning safety and risk in Japanese power plants following the disastrous nuclear accident covers the following issues: the nuclear facility Fukushima Daiichi, site characterization, important technical equipment, important electro-technical equipment, personal; description of the accident progression in the Fukushima nuclear power plant: impact of the earthquake, impact of the tsunami, short-term measures of the operating personnel, pressure and temperature situation in the containments, restoration of the after-heat cooling system in the units 1/2 and 4, fuel element storage pool, summarized parameters during the accident progress; comparative analysis of the accident progression at the Fukushima Daiichi site.

Risk Assessment Strategy for Decommissioning of Fukushima Daiichi Nuclear Power Station

Directory of Open Access Journals (Sweden)

Akira Yamaguchi

2017-03-01

Full Text Available Risk management of the Fukushima Daiichi Nuclear Power Station decommissioning is a great challenge. In the present study, a risk management framework has been developed for the decommissioning work. It is applied to fuel assembly retrieval from Unit 3 spent fuel pool. Whole retrieval work is divided into three phases: preparation, retrieval, and transportation and storage. First of all, the end point has been established and the success path has been developed. Then, possible threats, which are internal/external and technical/societal/management, are identified and selected. “What can go wrong?” is a question about the failure scenario. The likelihoods and consequences for each scenario are roughly estimated. The whole decommissioning project will continue for several decades, i.e., long-term perspective is important. What should be emphasized is that we do not always have enough knowledge and experience of this kind. It is expected that the decommissioning can make steady and good progress in support of the proposed risk management framework. Thus, risk assessment and management are required, and the process needs to be updated in accordance with the most recent information and knowledge on the decommissioning works.

Risk assessment strategy for decommissioning of Fukushima Daiichi Nuclear Power Station

Energy Technology Data Exchange (ETDEWEB)

Yamaguchi, Akira; Jang, Sung Hoon [The University of Tokyo, Tokyo (Japan); Hida, Kazuki [Nuclear Damage Compensation and Decommissioning Facilitation Corporation, Tokyo (Japan); Yamanaka, Yasunori [Tokyo Electric Power Company Holdings, Tokyo (Japan); Narumiya, Yoshiyuki [The Kansai Electric Power Co., Inc., Osaka (Japan)

2017-03-15

Risk management of the Fukushima Daiichi Nuclear Power Station decommissioning is a great challenge. In the present study, a risk management framework has been developed for the decommissioning work. It is applied to fuel assembly retrieval from Unit 3 spent fuel pool. Whole retrieval work is divided into three phases: preparation, retrieval, and transportation and storage. First of all, the end point has been established and the success path has been developed. Then, possible threats, which are internal/external and technical/societal/management, are identified and selected. “What can go wrong?” is a question about the failure scenario. The likelihoods and consequences for each scenario are roughly estimated. The whole decommissioning project will continue for several decades, i.e., long-term perspective is important. What should be emphasized is that we do not always have enough knowledge and experience of this kind. It is expected that the decommissioning can make steady and good progress in support of the proposed risk management framework. Thus, risk assessment and management are required, and the process needs to be updated in accordance with the most recent information and knowledge on the decommissioning works.

Mobilizing Mothers: The Fukushima Daiichi Nuclear Catastrophe and Environmental Activism in Japan

Directory of Open Access Journals (Sweden)

Nicole Freiner

2014-02-01

Full Text Available The citizens’ and environmental movements of the 1960s and 70s hadgreat political success in Japan, culminating in the Special Session of the Diet in1970 that enacted 14 anti-pollution laws. These activist groups fought denials ofresponsibility on the part of industry and unresponsiveness on the part of localgovernments. Women were at the forefront of this type of activism during the 1960sand 70s, and led many of the citizens’ environmental movements during this time.More recently, during the environmental catastrophe caused by the meltdown of theFukushima Daiichi nuclear plant, women and mothers have been vocal protesters.Environmental movements have particular political salience because of the successwomen have achieved in this area both in policy change and also roles in formalpolitics. Women have consistently achieved these successes at the same time as theyperformed their roles as mothers and home managers; these roles have been usedstrategically to mobilize women with great effect, and also were central to the valueswith which the citizens’ movements defined themselves politically.

Plutonium release from Fukushima Daiichi fosters the need for more detailed investigations

Science.gov (United States)

Schneider, Stephanie; Walther, Clemens; Bister, Stefan; Schauer, Viktoria; Christl, Marcus; Synal, Hans-Arno; Shozugawa, Katsumi; Steinhauser, Georg

2013-10-01

The contamination of Japan after the Fukushima accident has been investigated mainly for volatile fission products, but only sparsely for actinides such as plutonium. Only small releases of actinides were estimated in Fukushima. Plutonium is still omnipresent in the environment from previous atmospheric nuclear weapons tests. We investigated soil and plants sampled at different hot spots in Japan, searching for reactor-borne plutonium using its isotopic ratio 240Pu/239Pu. By using accelerator mass spectrometry, we clearly demonstrated the release of Pu from the Fukushima Daiichi power plant: While most samples contained only the radionuclide signature of fallout plutonium, there is at least one vegetation sample whose isotope ratio (0.381 +/- 0.046) evidences that the Pu originates from a nuclear reactor (239+240Pu activity concentration 0.49 Bq/kg). Plutonium content and isotope ratios differ considerably even for very close sampling locations, e.g. the soil and the plants growing on it. This strong localization indicates a particulate Pu release, which is of high radiological risk if incorporated.

Achievement report for fiscal 1998 on joint research business (2/2). Photovoltaic power generation field test for public facilities; 1998 nendo kokyo shisetsu nadoyo taiyoko hatsuden field test jigyo (2/2). Kyodo kenkyu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-07-01

Photovoltaic power generation systems are experimentally installed at public facilities at various locations, and subjected to field tests in which they experience long-term operation under real loads. Mie Prefectural Iidaka Senior/Junior High School has a 10kW solar cell system installed on the south-side roof of the school house. The system is linked to an in-house transformation station and the power generated by the system is supplied to the lighting and air-conditioning facilities in the building, and surplus if any is transmitted to the Chubu Electric Power Co., Inc., system. A field test is being conducted to determine if there are usability and safety in the 10kW system. A number of like systems are undergoing field tests, installed at a comprehensive technological training center of Kyushu Electric Power Safety Association, Kongo Gakuen Senior High School, Sakata Nursery School, Taiyo Daiichi Nursery School, Minami Kindergarten, Neyagawa Ishizu Old People's Home, Co-Op Living Konan, Factory Hishimeki, Tochigi Fuji Industries, Gamo-cho Hirabayashi Public Hall, Fukuoka Prefectural Culture Complex, Yatsusugi Forest Schooling Center, Osaka Prefectural Murano Water Purification Plant, Yamanashi Institute of Environmental Sciences, Utatsu-cho Town Office, Ginga Gakuen Junior High School, etc. (NEDO)

Achievement report for fiscal 1998 on joint research business (2/2). Photovoltaic power generation field test for public facilities; 1998 nendo kokyo shisetsu nadoyo taiyoko hatsuden field test jigyo (2/2). Kyodo kenkyu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-07-01

Photovoltaic power generation systems are experimentally installed at public facilities at various locations, and subjected to field tests in which they experience long-term operation under real loads. Mie Prefectural Iidaka Senior/Junior High School has a 10kW solar cell system installed on the south-side roof of the school house. The system is linked to an in-house transformation station and the power generated by the system is supplied to the lighting and air-conditioning facilities in the building, and surplus if any is transmitted to the Chubu Electric Power Co., Inc., system. A field test is being conducted to determine if there are usability and safety in the 10kW system. A number of like systems are undergoing field tests, installed at a comprehensive technological training center of Kyushu Electric Power Safety Association, Kongo Gakuen Senior High School, Sakata Nursery School, Taiyo Daiichi Nursery School, Minami Kindergarten, Neyagawa Ishizu Old People's Home, Co-Op Living Konan, Factory Hishimeki, Tochigi Fuji Industries, Gamo-cho Hirabayashi Public Hall, Fukuoka Prefectural Culture Complex, Yatsusugi Forest Schooling Center, Osaka Prefectural Murano Water Purification Plant, Yamanashi Institute of Environmental Sciences, Utatsu-cho Town Office, Ginga Gakuen Junior High School, etc. (NEDO)

Qualification of Daiichi Units 1, 2, and 3 Data for Severe Accident Evaluations - Process and Illustrative Examples from Prior TMI-2 Evaluations

Energy Technology Data Exchange (ETDEWEB)

Rempe, Joy Lynn [Idaho National Lab. (INL), Idaho Falls, ID (United States); Knudson, Darrell Lee [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2014-09-01

The accidents at the Three Mile Island Unit 2 (TMI-2) Pressurized Water Reactor (PWR) and the Daiichi Units 1, 2, and 3 Boiling Water Reactors (BWRs) provide unique opportunities to evaluate instrumentation exposed to severe accident conditions. Conditions associated with the release of coolant and the hydrogen burn that occurred during the TMI-2 accident exposed instrumentation to harsh conditions, including direct radiation, radioactive contamination, and high humidity with elevated temperatures and pressures. As part of a program initiated in 2012 by the Department of Energy Office of Nuclear Energy (DOE-NE), a review was completed to gain insights from prior TMI-2 sensor survivability and data qualification efforts. This initial review focused on the set of sensors deemed most important by post-TMI-2 instrumentation evaluation programs. Instrumentation evaluation programs focused on data required by TMI-2 operators to assess the condition of the reactor and containment and the effect of mitigating actions taken by these operators. In addition, prior efforts focused on sensors providing data required for subsequent forensic evaluations and accident simulations. To encourage the potential for similar activities to be completed for qualifying data from Daiichi Units 1, 2, and 3, this report provides additional details related to the formal process used to develop a qualified TMI-2 data base and presents data qualification details for three parameters: primary system pressure; containment building temperature; and containment pressure. As described within this report, sensor evaluations and data qualification required implementation of various processes, including comparisons with data from other sensors, analytical calculations, laboratory testing, and comparisons with sensors subjected to similar conditions in large-scale integral tests and with sensors that were similar in design to instruments easily removed from the TMI-2 plant for evaluations. As documented

IAEA International Peer Review Mission on Mid-and-Long-Term Roadmap Towards the Decommissioning of TEPCO's Fukushima Daiichi Nuclear Power Station Units 1-4, Tokyo and Fukushima Prefecture, Japan, 15-22 April 2013. Mission Report

International Nuclear Information System (INIS)

2013-01-01

Following the accident at TEPCO's Fukushima Daiichi Nuclear Power Station (NPS) on 11 March 2011, the ''Mid-and-Long-Term Roadmap towards the Decommissioning of TEPCO's Fukushima Daiichi Nuclear Power Station Units 1-4'' was adopted by the Government of Japan and TEPCO Council on Mid-to-Long-Term Response for Decommissioning in December 2011 and revised in July 2012. The Roadmap, which is scheduled for an additional update in June 2013, describes the main steps and activities to be implemented for the decommissioning of the Fukushima Daiichi NPS through the combined efforts of the Government of Japan and TEPCO. Within the framework of the IAEA Action Plan on Nuclear Safety, the Government of Japan invited the IAEA to conduct an independent peer review of the Roadmap with two main objectives: - To improve the decommissioning planning and the implementation of pre-decommissioning activities at TEPCO's Fukushima Daiichi NPS; and - To share with the international community the good practices and lessons learned by the review. The review has been organized in two steps, and the IAEA conducted the first part in Japan from 15 to 22 April 2013. The objective of the first mission was to undertake an initial review of the Roadmap, including assessments of decommissioning strategy, planning and timing of decommissioning phases and a review of several specific short-term issues and recent challenges. Specifically, it covered the assessment of current reactor conditions, assessment of management of radioactive releases and associated doses, control of radioactive exposure of employees and decontamination within the site for improvement of working environment, structural integrity of reactor buildings and other constructions. The incidents recently experienced at the site, related with failures of the power supply and leakages of water from the underground reservoirs, were also included in the review of the specific short-term issues. The Government of Japan and TEPCO have

Lessons Learned in Protection of the Public for the Accident at the Fukushima Daiichi Nuclear Power Plant.

Science.gov (United States)

Callen, Jessica; Homma, Toshimitsu

2017-06-01

What insights can the accident at the Fukushima Daiichi nuclear power plant provide in the reality of decision making on actions to protect the public during a severe reactor and spent fuel pool emergency? In order to answer this question, and with the goal of limiting the consequences of any future emergencies at a nuclear power plant due to severe conditions, this paper presents the main actions taken in response to the emergency in the form of a timeline. The focus of this paper is those insights concerning the progression of an accident due to severe conditions at a light water reactor nuclear power plant that must be understood in order to protect the public.

Lesson and learn from 'Fukushima Daiichi' 180 day's tweets. Inevitable NPP renaissance of the culture and technology

Energy Technology Data Exchange (ETDEWEB)

Tamaki, Masayoshi B., E-mail: a40507a@cc.nagoya-u.ac.jp [TAMAKI Memorial Inst., Komaki, Aichi (Japan)

2011-07-01

Tweeting for severe reactor accident of Toden-EPCO Fukushima Daiichi due to the Eastern Japan M9 earthquake brought me 'Nuclear Renaissance'. Along to the twitter-time-line of the accident consequences, the spent fuel pool, containment, hydrogen explosion, destroyed core, and contamination have been discussed as Inferno. 'Hairo' and back fitting of existing NPPs have been discussed as Purgatorio. NPP Renaissance through nuclear energy synergetics has been discussed as Paradiso. Through these discussions, the East Asia Rim Community takes the role of the 'KOU(one of the keywords in traditional East Asian game 'GO') for realizing 'Nuclear Renaissance' by the 22 Century, resulting in becoming the keystone of the development to the 'All Asia Community'. (author)

Lesson and learn from 'Fukushima Daiichi' 180 day's tweets. Inevitable NPP renaissance of the culture and technology

International Nuclear Information System (INIS)

Tamaki, Masayoshi B.

2011-01-01

Tweeting for severe reactor accident of Toden-EPCO Fukushima Daiichi due to the Eastern Japan M9 earthquake brought me 'Nuclear Renaissance'. Along to the twitter-time-line of the accident consequences, the spent fuel pool, containment, hydrogen explosion, destroyed core, and contamination have been discussed as Inferno. 'Hairo' and back fitting of existing NPPs have been discussed as Purgatorio. NPP Renaissance through nuclear energy synergetics has been discussed as Paradiso. Through these discussions, the East Asia Rim Community takes the role of the 'KOU(one of the keywords in traditional East Asian game 'GO') for realizing 'Nuclear Renaissance' by the 22 Century, resulting in becoming the keystone of the development to the 'All Asia Community'. (author)

Analyzing different HPCI operation modes simulated with ATHLET-CD regarding possible core degradation phenomena in Fukushima-Daiichi unit 3

Energy Technology Data Exchange (ETDEWEB)

Bratfisch, Christoph; Koch, Marco K. [Ruhr-Univ. Bochum (Germany). Reactor Simulation and Safety Group

2017-02-15

For extented application and analyses of the severe accident code ATHLET-CD, the course of the invessel accident in Unit 3 of Fukushima-Daiichi is simulated in the frame of the research project SUBA as a part of the BMBF sponsored collaborative project WASA-BOSS (Weiterentwicklung und Anwendung von Severe Accident Codes - Bewertung und Optimierung von Stoerfallmassnahmen). Investigations, carried out by TEPCO, had shown that the High-Pressure Coolant Injection system (HPCI) might have stopped earlier than expected. A parameter variation was performed to analyze the impact of the tripped HPCI injection regarding the thermohydraulic behaviour as well as the core degradation phenomena.

Local variance of atmospheric 14C concentrations around Fukushima Dai-ichi Nuclear Power Plant from 2010 to 2012

DEFF Research Database (Denmark)

Chen, Biying; Xu, Sheng; Cook, Gordon T.

2017-01-01

Radiocarbon (14C) has been measured in single tree ring samples collected from the southwest of the Fukushima Dai-ichi Nuclear Power Plant. Our data indicate south-westwards dispersion of radiocarbon and the highest 14C activity observed so far in the local environment during the 2011 accident....... The abnormally high 14C activity in the late wood of 2011 ring may imply an unknown source of radiocarbon nearby after the accident. The influence of 14C shrank from 30 km during normal reactor operation to 14 km for the accident in the northwest of FDNPP, but remains unclear in the southwest....

An update on radioactive release and exposures after the Fukushima Dai-ichi nuclear disaster.

LENUS (Irish Health Repository)

McLaughlin, P D

2012-09-01

On 11 March 2011, the Richter scale 0.9-magnitude Tokohu earthquake and tsunami struck the northeast coast of Japan, resulting in widespread injury and loss of life. Compounding this tragic loss of life, a series of equipment and structural failures at the Fukushima Dai-ichi nuclear power plant (FDNP) resulted in the release of many volatile radioisotopes into the atmosphere. In this update, we detail currently available evidence about the nature of immediate radioactive exposure to FDNP workers and the general population. We contrast the nature of the radioactive exposure at FDNP with that which occurred at the Chernobyl power plant 25 years previously. Prediction of the exact health effects related to the FDNP release is difficult at present and this disaster provides the scientific community with a challenge to help those involved and to continue research that will improve our understanding of the potential complications of radionuclide fallout.

Japan Reports New Water Leak at Fukushima Daiichi; IAEA Sees No Danger to Public

International Nuclear Information System (INIS)

2014-01-01

Full text: Japanese authorities have informed the IAEA that a leak from an overflowing water storage tank at TEPCO's Fukushima Daiichi Nuclear Power Station was detected in the late evening of 19 February 2014. About 100 cubic metres of radioactive water leaked to the ground adjacent to the tank storage area before the leak was stopped about six hours later. Based on the information provided, IAEA experts consider that the leak poses no danger to the public. IAEA experts also consider actions taken by Japan's Nuclear Regulatory Authority (NRA) following the leak to be appropriate. These include an NRA recommendation that TEPCO remove soil contaminated by the leaked water, which will reduce the risk that contaminated water will be spread further through rain and groundwater. Japan has not asked the IAEA for any assistance in connection with the leak from the tank. The IAEA will continue monitoring developments. (IAEA)

Results of stress tests of European nuclear power plants after the Fukushima-Daiichi accident

International Nuclear Information System (INIS)

Kovacs, Zoltan; Novakova, Helena

2012-01-01

In response to the Fukushima-Daiichi accident, the European Council laid down the requirement that a transparent and comprehensive risk assessment exercise ('stress tests') be carried out at each European nuclear power plant. The stress tests concentrated on the nuclear power plants' safety margins in the light of the lessons learned from the accident. The reviews focused on natural external events including earthquake, tsunami and extreme weather, loss of safety functions, and severe accident management. The stress test procedure comprised 3 steps: (i) The nuclear facility operators performed the stress tests and prepared proposals for safety improvements. (ii) The national regulators performed independent reviews of the stress tests and prepared national reports. (iii) The reports submitted by the national regulators were subjected to review at a European level. The article describes the scope of the stress tests and their results, verified at the European level. (orig.)

Fukushima Daiichi unit 1 uncertainty analysis--Preliminary selection of uncertain parameters and analysis methodology

Energy Technology Data Exchange (ETDEWEB)

Cardoni, Jeffrey N.; Kalinich, Donald A.

2014-02-01

Sandia National Laboratories (SNL) plans to conduct uncertainty analyses (UA) on the Fukushima Daiichi unit (1F1) plant with the MELCOR code. The model to be used was developed for a previous accident reconstruction investigation jointly sponsored by the US Department of Energy (DOE) and Nuclear Regulatory Commission (NRC). However, that study only examined a handful of various model inputs and boundary conditions, and the predictions yielded only fair agreement with plant data and current release estimates. The goal of this uncertainty study is to perform a focused evaluation of uncertainty in core melt progression behavior and its effect on key figures-of-merit (e.g., hydrogen production, vessel lower head failure, etc.). In preparation for the SNL Fukushima UA work, a scoping study has been completed to identify important core melt progression parameters for the uncertainty analysis. The study also lays out a preliminary UA methodology.

Rapid analysis of U isotopes in vegetables using ICP-MS. Application to the emergency U monitoring after the nuclear accident at TEPCO's Fukushima Dai-ichi power station

International Nuclear Information System (INIS)

Jian Zheng; Keiko Tagami; Shigeo Uchida

2012-01-01

After the nuclear accident at TEPCO's Fukushima Dai-ichi power station in March, hydrogen explosions and reactor building explosion resulted in releases of radionuclides in the environment. Severe radioactive cesium and iodine contaminations have been observed in fallout deposition samples and soils in the East Japan. Radioactive cesium, iodine, uranium, and transuranic radionuclides were set as the monitoring targets in food safety tests. However, so far, only radioactive cesium and iodine were daily measured and reported by the Ministry of Health, Labour, and Welfare. The tedious and time consuming conventional alpha spectrometric method hampered the emergency monitoring U contamination in foods. In this work, we propose a simple and rapid analytical method for 238 U and 235 U/ 238 U isotope ratio analysis in fresh vegetables. This method was applied to the emergency monitoring of radioactive contamination after the nuclear accident at TEPCO's Fukushima Dai-ichi power station. The results showed no U contamination in fresh vegetables collected in Chiba and Ibaraki prefectures in April and May, 2011. (author)

ABWR1. A Generation III.7 reactor after the Fukushima Daiichi accident

International Nuclear Information System (INIS)

Sato, Takashi; Matsumoto, Keiji; Kurosaki, Toshikazu; Taguchi, Keisuke

2015-01-01

iB1350 stands for an innovative, intelligent and inexpensive BWR 1350. It is the first Generation III.7 reactor after the Fukushima Daiichi accident. It has incorporated lessons learned from the Fukushima Daiichi accident and WENRA safety objectives. It has innovative safety to cope with devastating natural disasters including a giant earthquake, a large tsunami and a monster hurricane. The iB1350 can survive passively such devastation and a very prolonged SBO without any support from the outside of a site up to 7 days even preventing core melt. It, however, is based on the well-established proven ABWR design. The NSSS is exactly the same as that of the current ABWR. As for safety design it has a double cylinder RCCV (Mark W containment) and an in-depth hybrid safety system (IDHS). The Mark W containment has double FP confinement barriers and the in-containment filtered venting system (IFVS) that enable passively no emergency evacuation outside the immediate vicinity of the plant for a SA. It has a large volume to hold hydrogen, a core catcher, a passive flooding system and an innovative passive containment cooling system (iPCCS) establishing passively practical elimination of containment failure even in a long term. The IDHS consists of 4 division active safety systems for a DBA, 2 division active safety systems for a SA and built-in passive safety systems (BiPSS) consisting of an isolation condenser (IC) and the iPCCS for a SA. The IC/PCCS pools have enough capacity for 7 day grace period. The IC/PCCS heat exchangers, core and spent fuel pool are enclosed inside the CV building and protected against a large airplane crash. The iB1350 can survive a large airplane crash only by the CV building and the built-in passive safety systems therein. The dome of the CV building consists of a single wall made of steel and concrete composite. This single dome structure facilitates a short-term construction period and cost saving. The CV diameter is smaller than that of most

Japan's compensation system for nuclear damage - As related to the TEPCO Fukushima Daiichi nuclear accidents

International Nuclear Information System (INIS)

Nomura, Toyohiro; Matsuura, Shigekazu; Takahashi, Yasufumi; Takenaka, Chihiro; Hokugo, Taro; Kamada, Toshihiko; Kamai, Hiroyuki

2012-01-01

Following the TEPCO Fukushima Daiichi nuclear power plant accident, extraordinary efforts were undertaken in Japan to implement a compensation scheme for the proper and efficient indemnification of the affected victims. This publication provides English translations of key Japanese legislative and administrative texts and other implementing guidance, as well as several commentaries by Japanese experts in the field of third party nuclear liability. The OECD Nuclear Energy Agency (NEA) has prepared this publication in co-operation with the government of Japan to share Japan's recent experience in implementing its nuclear liability and compensation regime. The material presented in the publication should provide valuable insights for those wishing to better understand the regime applied to compensate the victims of the accident and for those working on potential improvements in national regimes and the international framework for third party nuclear liability

Aerial radiation monitoring around the Fukushima Dai-ichi Nuclear Power Plant using an unmanned helicopter.

Science.gov (United States)

Sanada, Yukihisa; Torii, Tatsuo

2015-01-01

The Great East Japan Earthquake on March 11, 2011 generated a series of large tsunami that seriously damaged the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), which resulted in the release of radioactive materials into the environment. To provide further details regarding the distribution of air dose rate and the distribution of radioactive cesium ((134)Cs and (137)Cs) deposition on the ground within a radius of approximately 5 km from the nuclear power plant, we carried out measurements using an unmanned helicopter equipped with a radiation detection system. The distribution of the air dose rate at a height of 1 m above the ground and the radioactive cesium deposition on the ground was calculated. Accordingly, the footprint of radioactive plumes that extended from the FDNPP was illustrated. Copyright © 2014 Elsevier Ltd. All rights reserved.

Regional long-term model of radioactivity dispersion and fate in the Northwestern Pacific and adjacent seas: application to the Fukushima Dai-ichi accident.

Science.gov (United States)

Maderich, V; Bezhenar, R; Heling, R; de With, G; Jung, K T; Myoung, J G; Cho, Y-K; Qiao, F; Robertson, L

2014-05-01

The compartment model POSEIDON-R was modified and applied to the Northwestern Pacific and adjacent seas to simulate the transport and fate of radioactivity in the period 1945-2010, and to perform a radiological assessment on the releases of radioactivity due to the Fukushima Dai-ichi accident for the period 2011-2040. The model predicts the dispersion of radioactivity in the water column and in sediments, the transfer of radionuclides throughout the marine food web, and subsequent doses to humans due to the consumption of marine products. A generic predictive dynamic food-chain model is used instead of the biological concentration factor (BCF) approach. The radionuclide uptake model for fish has as a central feature the accumulation of radionuclides in the target tissue. The three layer structure of the water column makes it possible to describe the vertical structure of radioactivity in deep waters. In total 175 compartments cover the Northwestern Pacific, the East China and Yellow Seas and the East/Japan Sea. The model was validated from (137)Cs data for the period 1945-2010. Calculated concentrations of (137)Cs in water, bottom sediments and marine organisms in the coastal compartment, before and after the accident, are in close agreement with measurements from the Japanese agencies. The agreement for water is achieved when an additional continuous flux of 3.6 TBq y(-1) is used for underground leakage of contaminated water from the Fukushima Dai-ichi NPP, during the three years following the accident. The dynamic food web model predicts that due to the delay of the transfer throughout the food web, the concentration of (137)Cs for piscivorous fishes returns to background level only in 2016. For the year 2011, the calculated individual dose rate for Fukushima Prefecture due to consumption of fishery products is 3.6 μSv y(-1). Following the Fukushima Dai-ichi accident the collective dose due to ingestion of marine products for Japan increased in 2011 by a

Changing information needs of social impact of nuclear power plant siting. Through a comparison before and after the Fukushima Daiichi nuclear power plant accident

International Nuclear Information System (INIS)

Kashiwa, Takako; Kawamoto, Yoshimi

2013-01-01

In the light of the Fukushima Daiichi nuclear power plant accident, we need to consider a symbiosis method based on the diminution of the nuclear power industry. To find a region that does not excessively depend on the nuclear power industry, it is necessary to examine and discuss the social impact of nuclear-related industries. In this study, we compared people's changing information needs of social impact before and after the Fukushima Daiichi nuclear power plant accident. It was found that the need for information increased after the accident. In particular, there were three research areas where the need for information increased: the consideration of building nuclear power plants, the influence of harmful rumors on the region, and influence on the nuclear power industry. Next, attempts were made to understand whether there is a difference between information needs of social impact by attributes, such as age, sex and knowledge of nuclear power. The information needs of the following categories of people increased after the accident: people aged between 10 and 50 years, women, people who do not have a clear opinion about the use of a nuclear power plant, and people who do not have any knowledge of nuclear power. (author)

The Human Aspect of the Fukushima Daiichi Accident

International Nuclear Information System (INIS)

Anegawa, T.; Kawano, A.

2016-01-01

Recognizing itself as the main party involved in the nuclear accident triggered by the Tohoku-Chihou-Taiheiyo-Oki Earthquake on March 11, 2011, Tokyo Electric Power Company (TEPCO) has performed accident investigation from various aspects. Results of the investigation are reported mainly in two reports; (1) Fukushima Nuclear Accident Analysis Report (June 20, 2012), which identified the timeline and the proximate causes of the accident, and (2) Summary of Fukushima Nuclear Accident and Nuclear Safety Reform Plan (March 29, 2013) to set forth the results of the investigation and provide an analysis of the background factors surrounding the accident and countermeasures taken. This presentation will first provide overview of the accident response at Fukushima Daiichi and Daini Nuclear Power Stations. Voices from the first responders at the sites will be introduced in order to share thoughts of individuals involved in the emergency response. Summary of retrospective study of the accident by one of the shift supervisors at the time of the accident will be presented in order to share the facts that happened at main control rooms. The shift supervisor and his crew had to manage the situation for extended period of time that exceeded the scenarios that they had been trained, in a situation with no lightning and high radiation condition. During the accident response, shift supervisors had to decide to dispatch some of his crew members to the field to open valves, check the status of equipment etc., in the situation where the high radiation exposure is foreseen. The presentation will include conflict of shift supervisors and crew focusing on the human aspects. In addition, actions being taken at the Emergency Response Centers (ERC) set up at the seismic-isolated building on-site and the Headquarters in Tokyo will be shared focusing on the human aspects related to the accident progress. This includes difficult decisions to dispatch first responders to the field, in the

Morphological abnormalities in gall-forming aphids in a radiation-contaminated area near Fukushima Daiichi: selective impact of fallout?

Science.gov (United States)

Akimoto, Shin-ichi

2014-01-01

To evaluate the impact of fallout from the Fukushima Daiichi Nuclear Power Plant accident on organisms, this study compared the morphology and viability of gall-forming aphids between the Fukushima population and control populations from noncontaminated areas. This study, in particular, focused on the morphology of first-instar gall formers derived from the first sexual reproduction after the accident. Of 164 first instars from Tetraneura sorini galls collected 32 km from Fukushima Daiichi in spring 2012, 13.2% exhibited morphological abnormalities, including four conspicuously malformed individuals (2.4%). In contrast, in seven control areas, first instars with abnormal morphology accounted for 0.0–5.1% (on average, 3.8%). The proportions of abnormalities and mortality were significantly higher in Fukushima than in the control areas. Similarly, of 134 first instars from T. nigriabdominalis galls, 5.9% exhibited morphological abnormalities, with one highly malformed individual. However, of 543 second-generation larvae produced in T. sorini galls, only 0.37% had abnormalities, suggesting that abnormalities found in the first generation were not inherited by the next generation. Although investigation is limited to one study site, this result suggests that radioactive contamination had deleterious effects on embryogenesis in eggs deposited on the bark surface, but a negligible influence on the second generation produced in closed galls. Furthermore, analysis of both species samples collected in spring 2013 indicated that the viability and healthiness of the aphids were significantly improved compared to those in the 2012 samples. Thus, the results of this study suggest the possibility that a reduced level of radiation and/or selection for radiation tolerance may have led to the improved viability and healthiness of the Fukushima population. PMID:24634721

A Study on Pyrochemical Process for Treating Fuel Debris from the Fukushima-Daiichi Reactors

International Nuclear Information System (INIS)

Sakamura, Y.; Iizuka, M.; Koyama, T.; Kitawaki, S.; Nakayoshi, A.; Kofuji, H.

2015-01-01

After the severe accident at Fukushima-daiichi nuclear power plants, CRIEPI and JAEA started a feasibility study on the pyrochemical treatment of the corium that mainly consists of UO 2 -ZrO 2 solid solution. In this study, reduction behaviours of zirconium oxide compounds were investigated in LiCl-Li 2 O salt bath at 923 K. It was experimentally verified that uranium in the simulated corium could be reduced to the metallic form and a part of zirconium was converted to Li 2 ZrO 3 . At higher Li 2 O concentrations in LiCl, Li 2 ZrO 3 was converted to Li 6 Zr 2 O 7 and Li 8 ZrO 6 . In the subsequent electrorefining, Li 2 ZrO 3 reacts with UCl 3 dissolved in the electrolyte salt to give UO 2 precipitate. Therefore, how to remove the Li 2 ZrO 3 from the reduction product is a key point for the pyrochemical treatment of the corium. (authors)

Advances in safety countermeasures at the Tomari NPP of Hokkaido Electric Power on the basis of Fukushima Daiichi NPP accident. Fire protection and other advances

International Nuclear Information System (INIS)

Shibata, Taku; Dasai, Katsumi

2014-01-01

Fire protections for the nuclear power plants have been based on the fire laws and the conventional guide. After Fukushima Daiichi NPP accident, many safety countermeasures - also about Fire Protection - have been discussed in the Japanese authorities. This paper shows our present activities in the Tomari NPP about the fire protections from the view points of Fire Prevention, Fire Detection/Suppression Systems and Fire Protection, and other advances. (author)

A numerical study on oceanic dispersion and sedimentation of radioactive cesium-137 from Fukushima Daiichi Nuclear Power Plant

International Nuclear Information System (INIS)

Higashi, Hironori; Morino, Yu; Ohara, Toshimasa

2014-01-01

We discussed a numerical model for oceanic dispersion and sedimentation of radioactive cesium-137 (Cs-137) in shallow water regions to clarify migration behavior of Cs-137 from Fukushima Daiichi Nuclear Power Plant. Our model considered oceanic transport by three dimensional ocean current, adsorption with large particulate matter (LPM), sedimentation and resuspension. The simulation well reproduced the spatial characteristics of sea surface concentration and sediment surface concentration of Cs-137 off Miyagi, Fukushima, and Ibaraki Prefectures during May-December 2011. The simulated results indicated that the adsorption-sedimentation of Cs-137 significantly occurred during strong wind events because the large amount of LPM was transported to upward layer by resuspension and vertical mixing. (author)

Groundwater flow modeling focused on the Fukushima Daiichi Nuclear Power Plant Site

International Nuclear Information System (INIS)

Saegusa, Hiromitsu; Onoe, Hironori; Kohashi, Akio; Watanabe, Masahisa

2015-01-01

Fukushima Daiichi nuclear power plant of Tokyo Electric Power Company is facing contaminated water issues in the aftermath of the Great East Japan Earthquake on March 11, 2011. The amount of contaminated water is continuously increasing due to groundwater leakage into the underground part of reactor and turbine buildings. Therefore, it is important to understand the groundwater flow conditions at the site and to predict the impact of countermeasures taken for isolating groundwater from the source of the contamination, i.e. the reactor buildings. Installations, such as of land-side and sea-side impermeable walls have been planned as countermeasures. In this study, groundwater flow modeling has been performed to estimate the response of groundwater flow conditions to the countermeasures. From the modeling, groundwater recharge and discharge areas, major groundwater flow direction, inflow rate into underground part of the buildings, and changes in response to implementation of the countermeasures could be reasonably estimated. The results indicate that the countermeasures will decrease the volume of inflow into the underground part of the buildings. This means that the countermeasures will be effective in reducing the discharge volume of contaminated groundwater to ocean. (author)

Problems of probabilistic safety assessment after Fukushima Daiichi nuclear power plant accident

International Nuclear Information System (INIS)

Sugiyama, Naoki

2011-01-01

Probabilistic safety assessment (PSA) methodology to assure nuclear safety is had great expectations of lessons learned from Fukushima Daiichi nuclear power plant (NPP) accident and on the other hand this accident made actualized technical problems of PSA. Effectiveness of current PSA methodology for risk assessment was confirmed by comparing the accident development with accident scenario of PSA and equipment failure rate. From a viewpoint of nuclear safety objective and defense in depth approach of IAEA, technical problems of PSA were (1) extension of PSA for spent fuel pool and waste disposal system as well as level 3PSA for broader environmental contamination and (2) overlapping of accident scenario of plural unit site, balance of high quality plant management and preceding negation, treatment of uncertainty of external events, severe accident measure and human reliability analysis and reflection of disaster prevention capability to level 3PSA. In order to upgrade PSA technology, six proposals were described for nuclear safety and defense in depth, comprehensive evaluation scope and catch-up of latest technology, necessity of strategic preparation of PSA standard, human resources fostering and risk communication. (T. Tanaka)

Analysis of the accident at Fukushima Daiichi nuclear power plant in an A BWR reactor

International Nuclear Information System (INIS)

Escorcia O, D.; Salazar S, E.

2016-09-01

The present work aims to recreate the accident occurred at the Fukushima Daiichi nuclear power plant in Japan on March 11, 2011, making use of an academic simulator of forced circulation of the A BWR reactor provided by the IAEA to know the scope of this simulator. The simulator was developed and distributed by the IAEA for academic purposes and contains the characteristics and general elements of this reactor to be able to simulate transients and failures of different types, allowing also to observe the general behavior of the reactor, as well as several phenomena and present systems in the same. Is an educational tool of great value, but it does not have a scope that allows the training of plant operators. To recreate the conditions of the Fukushima accident in the simulator, we first have to know what events led to this accident, as well as the actions taken by operators and managers to reduce the consequences of this accident; and the sequence of events that occurred during the course of the accident. Differences in the nuclear power plant behavior are observed and interpreted throughout the simulation, since the Fukushima plant technology and the simulator technology are not the same, although they have several elements in common. The Fukushima plant had an event that by far exceeded the design basis, which triggered in an accident that occurred in the first place by a total loss of power supply, followed by the loss of cooling systems, causing a level too high in temperature, melting the core and damaging the containment accordingly, allowing the escape of hydrogen and radioactive material. As a result of the simulation, was determined that the scope of the IAEA academic simulator reaches the entrance of the emergency equipment, so is able to simulate almost all the events occurred at the time of the earthquake and the arrival of the tsunami in the nuclear power plant of Fukushima Daiichi. However, due to its characteristics, is not able to simulate later

NIRS external dose estimation system for Fukushima residents after the Fukushima Dai-ichi NPP accident

Science.gov (United States)

Akahane, Keiichi; Yonai, Shunsuke; Fukuda, Shigekazu; Miyahara, Nobuyuki; Yasuda, Hiroshi; Iwaoka, Kazuki; Matsumoto, Masaki; Fukumura, Akifumi; Akashi, Makoto

2013-04-01

The great east Japan earthquake and subsequent tsunamis caused Fukushima Dai-ichi Nuclear Power Plant (NPP) accident. National Institute of Radiological Sciences (NIRS) developed the external dose estimation system for Fukushima residents. The system is being used in the Fukushima health management survey. The doses can be obtained by superimposing the behavior data of the residents on the dose rate maps. For grasping the doses, 18 evacuation patterns of the residents were assumed by considering the actual evacuation information before using the survey data. The doses of the residents from the deliberate evacuation area were relatively higher than those from the area within 20 km radius. The estimated doses varied from around 1 to 6 mSv for the residents evacuated from the representative places in the deliberate evacuation area. The maximum dose in 18 evacuation patterns was estimated to be 19 mSv.

Radiological surveillance in Mexico, derived of the accident of the Fukushima Daiichi nuclear power plant; Vigilancia radiologica en Mexico, derivado del accidente en la central nuclear de Fukushima Daiichi

Energy Technology Data Exchange (ETDEWEB)

Aguirre G, J.; Nohpal J, X., E-mail: jaguirre@cnsns.gob.mx [Comision Nacional de Seguridad Nuclear y Salvaguardias, Departamento de Vigilancia Radiologica, Dr. Barragan No. 779, Col. Narvarte, 03020 Mexico D. F. (Mexico)

2012-10-15

March 11, 2011 an earthquake of 9.0 grades in the Richter scale, originated in the coast of Tohoku, Japan, in the Pacific Ocean gave origin to a tsunami that caused an accident in the Fukushima Daiichi nuclear power plant. Due to this accident, derived of the loss of the reactor cooling system, as well as of the prolonged absence of alternating and direct current, radiological protection actions were realized without being able to avoid the liberation of radioactive material to the atmosphere and ocean. The radiological impact of these liberations, not only in Japan but around the world, mainly in the north hemisphere of the Earth, was analyzed by means of environmental dose measurements and radionuclide concentrations in soil and water, among others. In the Mexico case, air samples data were obtained, as well as environmental dose celerity and full-length counts of the people coming from Japan near the disaster area. The present work contains the obtained results of the realized measurements in Mexico, same that have been used to make a summary and analysis of the dispersion in the environment in several countries of the world. (Author)

Proceedings of the international symposium on environmental monitoring and dose estimation of residents after accident of TEPCO's Fukushima Daiichi Nuclear Power Stations

International Nuclear Information System (INIS)

Takahashi, Sentaro; Yamana, Hajimu; Takahashi, Tomoyuki; Takamiya, Koichi; Fukutani, Satoshi; Sato, Nobuhiro; Nakatani, Maki

2013-02-01

In March 2011, a massive earthquake and the resulting tsunami struck the Tohoku area in Japan, causing serious damages to TEPCO's Fukushima Daiichi nuclear plant and the release of a significant quantity of radionuclides into the surrounding environment. This accident underlined the necessity of establishing new and comprehensive scientific research for promoting safety in nuclear technology. With this aim, the Kyoto University Research Reactor Institute (KURRI) developed a new research program called the “KUR Research Program for Scientific Basis of Nuclear Safety” from this year. In this program, we are planning to hold an annual series of international symposiums along with many other research activities. The first in this series of symposiums, entitled “The International Symposium on Environmental Monitoring and Dose Estimation of Residents after Accident of TEPCO's Fukushima Daiichi Nuclear Power Station,” deals with the radiological effect of the March 2011 accident in Fukushima Daiichi NPP on the public. The purpose of this symposium is to collate data on environmental radioactivity anadiation dose in residents, discuss and verify these data, and clarify the actual situation of environmental contamination anesultant radiation exposed to the residents. We believe that an accurate estimation of the radiation dose is quite essential for planning for the healthy life and mental contentment of the residents, and we hope that many researchers who are studying the radiological effects of the accident will join us for these purposes. The environmental monitoring data are important for the dose assessment for residents. However, the monitoring data in the early stage are not sufficient for dose assessment, particularly near the NPP site, because of the confusion and blackout caused by the earthquake. However, many researchers and organizations in Japan and other countries have independently carried out radiation monitoring. We believe that the publication and

Examination of a measuring method for fallout radioactivity released by the accident of the Fukushima Dai-ichi NPS. Surface contamination measurement

International Nuclear Information System (INIS)

Yoshii, Taiki; Kawasaki, Satoru

2013-08-01

Radioactive nuclides were released in the atmosphere by the accident of TEPCO's Fukushima Dai-ichi Nuclear Power Station in March, 2011, and they are detected on the materials that had no artificial radioactive nuclides before the accident. Confronted with this situation, NISA issued a guideline titled 'A guideline regarding treatment of materials in nuclear facilities considering the influence of fallout released from the accident of TEPCO's Fukushima Dai-ichi Nuclear Power Station' on March 30, 2012. Nuclear Regulatory Authority refers to applying the existing bylaw until the time to make decision of the updated bylaw. The guideline shows that after judging whether there is the influence of fallout or not, the conventional clearance and NR systems can be used when there is no influence of fallout. On the other hand, the special treatment is required when it is judged that there is the influence. This report describes a specific example of measuring method to evaluate the influence of fallout, in case of surface contamination. This report focused surface contamination of flat object as target. Preliminary investigation shows that the distribution of surface contamination due to fallout is near to lognormal distribution. Therefore, the sampling measurement can be adopted. The average surface contamination of target is decided from sampling data by using 90% upper confidence limit of Chebyshev inequality. Also, the minimum sampling number is decided. The evaluation of the influence of fallout is judged from the result of surface contamination measurement, weight of target and surface area of target. (author)

The Fukushima Daiichi Accident. Technical Volume 3/5. Emergency Preparedness and Response

International Nuclear Information System (INIS)

2015-08-01

This volume describes the key events and response actions from the onset of the accident at the Fukushima Daiichi nuclear power plant (NPP), operated by the Tokyo Electric Power Company (TEPCO), on 11 March 2011. It also describes the national emergency preparedness and response (EPR) system in place in Japan and the international EPR framework prior to the accident. It is divided into five sections. Section 3.1 describes the initial actions taken by Japan in response to the accident, involving: identification of the accident, notification of off-site authorities and activation of the response; mitigatory actions taken on-site; and initial off-site response. Section 3.2 describes the protective measures taken for personnel in response to the natural disaster, protection of emergency workers, medical management of emergency workers and the voluntary involvement of members of the public in the emergency response. Section 3.3 describes the protective actions and other response actions taken by Japan to protect the public. It addresses urgent and early protective actions; the use of a dose projection model, the System for Prediction of Environmental Emergency Dose Information (SPEEDI), as a basis for decisions on protective actions during the accident; environmental monitoring; provision of information to the public and international community; and issues related to international trade and waste management. Section 3.4 describes the transition from the emergency phase to the recovery phase. It also addresses the national analysis of the accident and the emergency response. Section 3.5 describes the response by the IAEA, other international organizations within the Inter- Agency Committee on Radiological and Nuclear Emergencies (IACRNE), the actions of IAEA Member States with regard to protective actions recommended to their nationals in Japan and the provision of international assistance. A summary, observations and lessons conclude each section. There are three

People's awareness toward power generation choices. Two and a half years after the Fukushima Daiichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Kitada, Atsuko

2014-01-01

INSS has conducted continuous opinion polls about nuclear power generation (NPG) sixteen times from 1993 to October 2013. The latest survey is the fourth one since the Fukushima Daiichi Nuclear Power Plant accident and comes two-and-a-half years after the accident. In this study those survey data were analyzed, and the results were as follows. (1) The percent of persons considering the use of NPG as inevitable has dropped a little, but 53% affirm NPG is necessary. (2) It was suggested that the problems such as the leakage of radioactive water at Fukushima Daiichi had a negative impact on the opinion toward use of NPG. (3) Because of the reduction of supply capacity due to long-term suspension of nuclear power plant operations, electric power was insufficient in summer and winter, but people were able to overcome the supply shortage by continuing their power-saving activities. The percentage of people who thought the electric power was insufficient did not increase in particular. The percent who thought a reduction of the NPG should cause the power supply to be unstable, has decreased gradually. (4) Even though five months before the survey was taken there was a nearly 10% electric rate hike to cover increased fuel costs due to having thermal power replace NPG, a lot of people did not think their own electric bill had increased from last year. This suggested that people do not pay much attention to their own electric bills after a rate hike. (5) Negative effects of long-term suspension of NPG have not been recognized and the presence of NPG has declined, and people's support for the policy target of 'zero nuclear power by the 2030s,' has not been reduced, even though the government has changed its goal. (author)

Key regulatory and safety issues emerging NEA activities. Lessons Learned from Fukushima Dai-ichi NPS Accident - Key Regulatory and Safety Issues

International Nuclear Information System (INIS)

Nakoski, John

2013-01-01

A presentation was provided on the key safety and regulatory issues and an update of activities undertaken by the NEA and its members in response to the accident at the Fukushima Daiichi nuclear power stations (NPS) on 11 March 2011. An overview of the accident sequence and the consequences was provided that identified the safety functions that were lost (electrical power, core cooling, and primary containment) that lead to units 1, 2, and 3 being in severe accident conditions with large off-site releases. Key areas identified for which activities of the NEA and member countries are in progress include accident management; defence-in-depth; crisis communication; initiating events; operating experience; deterministic and probabilistic assessments; regulatory infrastructure; radiological protection and public health; and decontamination and recovery. For each of these areas, a brief description of the on-going and planned NEA activities was provided within the three standing technical committees of the NEA with safety and regulatory mandates (the Committee on Nuclear Regulatory Activities - CNRA, the Committee on the Safety of Nuclear Installations - CSNI, and the Committee on Radiation Protection and Public Health - CRPPH). On-going activities of CNRA include a review of enhancement being made to the regulatory aspects for the oversight of on-site accident management strategies and processes in light of the lessons learned from the accident; providing guidance to regulators on crisis communication; and supporting the peer review of the safety assessments of risk-significant research reactor facilities in light of the accident. Within the scope of the CSNI mandate, activities are being undertaken to better understand accident progression; characteristics of new fuel designs; and a benchmarking study of fast-running software for estimating source term under severe accident conditions to support protective measure recommendations. CSNI also has ongoing work in human

Translocation of radiocesium released by the Fukushima Daiichi nuclear power plant accident in Japanese chestnut and chestnut weevil larvae

International Nuclear Information System (INIS)

Sasaki, Yoshito; Ishii, Yasuo; Abe, Hironobu; Mitachi, Katsuaki; Watanabe, Takayoshi; Niizato, Tadafumi

2016-01-01

To examine the translocation of radiocesium scattered by the Fukushima Daiichi nuclear power plant accident that occurred in March 2011 to the Japanese chestnut, we investigated the autoradiography and radiocesium concentration in each part of Japanese chestnuts. The Japanese chestnut fruit has a thin skin between the kernel (cotyledons) and shell; the kernel of the fruit is edible. The 137 Cs concentration in each part of the fruit was found to be almost the same at about 1.0 × 10 4 Bq·kg -1 DW, as well as leaves. The radiocesium concentration in chestnut weevil larvae found on the fruit was approximately one-seventh of that in the kernel. (author)

Visualization of information spreading among 'influencers' on Twitter after Fukushima Daiichi nuclear disaster

International Nuclear Information System (INIS)

Kobayashi, Saori; Onoue, Yosuke; Koyamada, Koji; Tsubokura, Masaharu; Torii, Hiroyuki A.; Uno, Kazuko

2017-01-01

In the aftermath of the Fukushima Daiichi nuclear disaster, there was confusion due to a flood of contradictory opinions about the effects of radiation. In this report data was collected of tweets relating to radiation in 2011. Our aim is to prevent such confusion in the future by considering improvements that should be made in communicating relevant information during times of large-scale disasters. Influencers, the individuals who had an impact on the spread of relevant information, are categorized in three groups based on the contents of their tweets. Our analysis showed that the influencers whose tweets were retweeted the most changed as time passed. We speculated that it was partially caused by the higher number of mutual mentions among the influencers in the group, and verified the hypothesis using network analysis. Results indicated that the density of connection among the influencers is relevant to the ease with which information spreads. (author)

Tracking of Airborne Radionuclides from the Damaged Fukushima Dai-Ichi Nuclear Reactors by European Networks

DEFF Research Database (Denmark)

Masson, O.; Baeza, A.; Bieringer, J.

2011-01-01

Radioactive emissions into the atmosphere from the damaged reactors of the Fukushima Dai-ichi nuclear power plant (NPP) started on March 12th, 2011. Among the various radionuclides released, iodine-131 (131I) and cesium isotopes (137Cs and 134Cs) were transported across the Pacific toward the North...... period and spatial variations across more than 150 sampling locations in Europe made it possible to characterize the contaminated air masses. After the Chernobyl accident, only a few measurements of the gaseous 131I fraction were conducted compared to the number of measurements for the particulate...... reactors have provided a significant amount of new data on the ratio of the gaseous 131I fraction to total 131I, both on a spatial scale and its temporal variation. It can be pointed out that during the Fukushima event, the 134Cs to 137Cs ratio proved to be different from that observed after the Chernobyl...

The Fukushima Daiichi Accident. Technical Volume 2/5. Safety Assessment

International Nuclear Information System (INIS)

2015-08-01

Technical Volume 1 of this report has described what happened during the accident at the Fukushima Daiichi nuclear power plant (NPP). This volume begins (Section 2.1) with a review of how the design basis of the site for external events was assessed initially and then reassessed over the life of the NPP. The section also describes the physical changes that were made to the units as a result. The remainder of the volume describes the treatment of beyond design basis events in the safety assessment of the site, the accident management provisions, the effectiveness of regulatory programmes, human and organizational factors and the safety culture, and the role of operating experience. Further background information is contained in three annexes included on the CD-ROM of this Technical Volume which describe analytical investigations of the accident along with information on topics such as system performance, defence in depth and severe accident phenomena. Section 2.2 provides an assessment of the systems that failed, resulting in a failure to maintain the fundamental safety functions in Units 1–3, which were in operation at the time of the tsunami and in which the reactor pressure vessels (RPV) and containment vessels failed. The section also describes Units 4-6, which were shut down at the time of the tsunami, and the site’s central spent fuel storage facility. Section 2.3 discusses the probabilistic and deterministic safety assessments of beyond design basis accidents (BDBAs) that had been performed for the plant and the insights from these assessments that had led to changes in the plant’s design. The section pays particular attention to the assessment of extreme natural hazards, such as the one which led to the total loss of AC power supply on the site. The additional loss of DC power supply in Units 1 and 2 played a key role in the progression of the accident because it impeded the diagnosis of plant conditions and made the operators unaware of the status of

Agricultural approaches of remediation in the outside of the Fukushima Daiichi nuclear power plant

Energy Technology Data Exchange (ETDEWEB)

Sato, Nobuaki [Tohoku University, 2-1-1 Katahira Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Saso, Michitaka [Toshiba Corporation Power Systems Company: 2-1 Ukishima-cho, Kawasaki-ku, Kawasaki, Kanagawa 210-0862 (Japan); Umeda, Miki [Japan Atomic Energy Agency, 4-29 Muramatsu, Tokai, Ibaraki 319-1184 (Japan); Fujii, Yasuhiko [Tokyo Institute of Technology:2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Amemiya, Kiyoshi [Hazama Corporation: 2-2-5 Toranomon, Minato-ku, Tokyo 105-8479 (Japan)

2013-07-01

This paper outlines agricultural approaches of remediation activity done in contaminated areas around the Fukushima Daiichi Nuclear Power Plant. About the decontamination examination of contaminated areas, we have tried the land scale test of a rice field before and after planting by the use of currently recommended methods. Since farmers would carry out the land preparation by themselves, generation of secondary radioactive waste should be as low as possible through the decontamination works. For the radioactive nuclide migration control of rice by wet rice production, several types of decontamination methods such as zeolite addition and potassium fertilization in the soil have been examined. The results are summarized in the 4 following points. 1) Plowing and water discharge are effective for removing radioactive cesium from rice field. 2) Additional potassium fertilization is effective for reducing cesium radioactivity in the product. 3) No significant difference is observed with or without the zeolite addition. 4) Very low transfer factor of cesium from soil to brown rice has been obtained compared with literature values.

Atmospheric radionuclides from Fukushima Dai-ichi nuclear accident detected in Lanzhou, China

Institute of Scientific and Technical Information of China (English)

邬家龙王赟; 孙卫; 罗伟立; 王延俊; 张飙

2015-01-01

After the Fukushima Dai-ichi nuclear power plant accident on March 11, 2011, the radioactivity released from the accident was transported around the globe by atmospheric processes. The radioactivity monitoring program on atmospheric particulate in Lanzhou, China was activated by GSCDC to detect the input radionu-clides through atmospheric transport. Several artificial radionuclides were detected and measured in aerosol samples from March 26 to May 2, 2011. The peaked activity concentrations (in mBq/m3) were: 1.194 (131I), 0.231 (137Cs), 0.173 (134Cs) and 0.008 (136Cs), detected on April 6, 2011. The average activity ratio of 131I/137Cs and 134Cs/137Cs in air were 13.5 and 0.78. The significant increase of 137Cs activity concentration, one order of magnitude higher than pre-Fukushima accident levels, in ground level aerosol was observed in 2013, as its re-suspension from soil. The back-trajectory analysis simulated by NOAA-ARL HYSPLIT shows a direct transfer of the air masses released from Fukushima to Lanzhou across the Pacific Ocean, North America and Europe at the height close to 9000 m AGL. The value of effective dose for inhalation is close to one millionth of the annual limit for the general public.

Restoration of water environment contaminated by radioactive cesium released from Fukushima Daiichi NPP

Energy Technology Data Exchange (ETDEWEB)

Takeshita, K.; Takahashi, H. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 157-8550 (Japan); Jinbo, Y. [CDM Cosulting Co.Ltd., 1-13-13 Tsukiji Chuo-ku Tokyo 104-0045 (Japan); Ishido, A. [Radwaste and Decommissioning Center, 1-7-6 Toranomon, Minato-ku, Tokyo 105-0001 (Japan)

2013-07-01

In the Fukushima Daiichi NPP Accident, large amounts of volatile radioactive nuclides, such as {sup 131}I, {sup 134}Cs and {sup 137}Cs, were released to the atmosphere and huge areas surrounding the nuclear site were contaminated by the radioactive fallout. In this study, a combined process with a hydrothermal process and a coagulation settling process was proposed for the separation of radioactive Cs from contaminated soil and sewage sludge. The coagulation settling operation uses Prussian Blue (Ferric ferrocyanide) and an inorganic coagulant. The recovery of Cs from sewage sludge sampled at Fukushima city (100.000 Bq/kg) and soil at a nearby village (55.000 Bq/kg), was tested. About 96% of Cs in the sewage sludge was removed successfully by combining simple hydrothermal decomposition and coagulation settling. However, Cs in the soil was not removed sufficiently by the combined process (Cs removal is only 56%). The hydrothermal decomposition with blasting was carried out. The Cs removal from the soil was increased to 85%. When these operations were repeated twice, the Cs recovery was over 90%. The combined process with hydrothermal blasting and coagulation settling is applicable to the removal of Cs from highly contaminated soil.

Time series changes in radiocaesium distribution in tea plants (Camellia sinensis (L.)) after the Fukushima Dai-ichi Nuclear Power Plant accident.

Science.gov (United States)

Hirono, Yuhei; Nonaka, Kunihiko

2016-02-01

Radiocaesium ((134)Cs and (137)Cs) release following the accident at the Fukushima Dai-ichi Nuclear Power Plant, belonging to the Tokyo Electric Power Company caused severe contamination of new tea plant (Camellia sinensis (L.)) shoots by radiocaesium in many prefectures in eastern Japan. Because tea plants are perennial crops, there is the fear that the contamination might last for a long time. The objectives of this study were to reveal time series changes in the distribution of radiocaesium in tea plants after radioactive fallout and to evaluate the effect of pruning on reduction of radiocaesium concentrations in new shoots growing next year. The experimental tea field was located in Shizuoka, Japan, approximately 400 km away from the Fukushima Dai-ichi Nuclear Power Plant in a southwest direction. Time series changes in radiocaesium concentrations in unrefined tea, a tea product primarily produced for making Japanese green tea, from May 2011 to June 2013 and distribution of radiocaesium in tea plants from May 2011 to May 2012 were monitored. The radiocaesium concentrations in unrefined tea exponentially decreased; the effective half-lives for (134)Cs and (137)Cs were 0.30 and 0.36 y during the first 2 y after the accident, respectively. With time, the highest concentrations of (137)Cs moved from the upper to the lower parts of plants. Medium pruning 2-3 months after the accident reduced the concentration of (137)Cs in new shoots harvested in the first crop season of the following year by 56% compared with unpruned tea plants; thus, pruning is an effective measure for reducing radiocaesium concentration in tea. Copyright © 2015 Elsevier Ltd. All rights reserved.

Report on results 1998. Research and development on fusion area. Part 1 (next generation optical substrate technology); 1998 nendo seika hokokusho. Yugo ryoiki kenkyu kaihatsu daiichi bunsatsu (jisedai hikari kiban gijutsu)

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-03-01

Emphasis was placed on the research on a planar apertured near-field head and a super-RENS (super-resolution near-field structure) method, as a near-field application element for replacing protruding probes, which has a number of difficult points in developing near-field recording into a practical system, and as a recording and reproducing method. The super-RENS method, as a result of the examination, has become capable of recording/detecting a mark of the minimum 60nm diameter, by the near-field, under conditions such as the most advanced optical disk size and the number of revolution of the disk. This means that a high density recording is possible which is at least 40 times as dense as a DVD (digital versatile disk). It was confirmed by an experiment that the high density was possible in the track pitch direction by the super-RENS method. As a result of the examination on the behavior of the near-field in the super-RENS disk, it revealed that signal detection by the transmitted light which had not been tried before was effective for the improvement of the performance. The smallest detectable mark size was 80nm, in which case CNR (carrier to noise ratio) was 6.4dB. These values are approximately the same level as in the signal detection by reflected light, and are insufficient to verify the superiority. (NEDO)

Nuclear Crisis Communications: The Plan Worked. A Critique of NRC Communications in the Fukushima Daiichi Reactor Crisis - 12073

Energy Technology Data Exchange (ETDEWEB)

Brenner, Eliot; Harrington, Holly; Schmidt, Rebecca [U.S. Nuclear Regulatory Commission, Rockville, MD 20852 (United States)

2012-07-01

'Call the AV-Photo folks and get someone in here to shoot b-roll. We'll never be able to accommodate the network cameras and the only way I can get this to the media is to produce it ourselves'. Eliot Brenner, Director NRC Office of Public Affairs, March 12, 2011. For the past four years we have been speaking to audiences at Waste Management about communications issues. Last year, though we were kept from attending because of the federal budget crisis, our surrogates described to you the lessons the nuclear industry should draw from the BP Gulf oil spill crisis. Those remarks were delivered 11 days before the Fukushima Daiichi tragedy became the nuclear landmark of a generation - an industry changing event with worldwide ramifications, both in science and regulation and in communications. Eliot Brenner cut his teeth on crisis communication in the aviation industry where tragedy unfolds rapidly. He has been a speech-writer to three cabinet secretaries, spokesman for the Federal Aviation Administration and now spokesman for the Nuclear Regulatory Commission since 2004. Holly Harrington manages the NRC crisis response program and has 26 years federal public affairs experience, including eight years at the Federal Emergency Management Agency. Her crisis experience includes the 1989 Loma Prieta earthquake, numerous hurricanes and floods, Sept 11, and, now Fukushima Daiichi. Rebecca Schmidt is a veteran government relations professional whose decades in Washington include service with the House Armed Services Committee, the House Budget Committee and the Secretary of Defense. Collectively, the Offices of Public Affairs and Congressional Affairs conducted the largest outreach for the agency since Three Mile Island. We worked with the basic rule, described to Waste Management last year just 11 days before Fukushima - communicate early, often and clearly. The response - while not without its problems and lessons - went as smoothly as a chaotic event like

Fukushima Daiichi Nuclear Accident; based on the Final Report of Atomic Energy Society of Japan

Science.gov (United States)

Sekimura, Naoto

2014-09-01

The Atomic Energy Society of Japan (AESJ) published the Final Report of the AESJ Investigation Committee on Fukushima Daiichi NPS Accident in March 2014. The AESJ is responsible to identify the underlying root causes of the accident through technical surveys and analyses, and to offer solutions for nuclear safety. At the Fukushima Daiichi, Units 1 to 3, which were under operation, were automatically shut down at 14:46 on March 11, 2011 by the Tohoku District-off the Pacific Ocean Earthquake. About 50 minutes later, the tsunami flooded and destroyed the emergency diesel generators, the seawater cooling pumps, the electric wiring system and the DC power for Units 1, 2 and 4, resulting in loss of all power except for an air-cooled emergency diesel generator at Unit 6. Unit 3 lost all AC power, and later lost DC before dawn of March 13. Cooling the reactors and monitoring the results were heavily dependent on electricity for high-pressure water injection, depressurizing the reactor, low pressure water injection, and following continuous cooling. In Unit 3, for example, recent re-evaluation in August 2014 by TEPCO shows that no cooling water was injected into the reactor core region after 8 PM on March 12, leading to the fuel melting from 5:30 AM on March 13. Even though seawater was injected from fire engines afterwards, the rupture of pressure vessel was caused and the majority of melted fuel dropped into the containment vessel of Unit 3. The estimation of amount of radioactive materials such as Xe-133, I-131, Cs-137 and Cs-134, emitted to the environment from Units 1 to 3 is discussed in the presentation. Direct causes of the accident identified in the AESJ Report were, 1) inadequate tsunami measures, 2) inadequate severe accident management measures and 3) inadequate emergency response, post-accident management/mitigation, and recovery measures. These were caused by the following underlying factors, i.e., a) lack of awareness on the roles and responsibilities by

The Fukushima Daiichi Nuclear Power Plant Accident: OECD/NEA Nuclear Safety Response and Lessons Learnt

International Nuclear Information System (INIS)

2013-01-01

Following the March 2011 accident at the Fukushima Daiichi nuclear power plant, all NEA member countries took early action to ensure and confirm the continued safety of their nuclear power plants and the protection of the public. After these preliminary safety reviews, all countries with nuclear facilities carried out comprehensive safety reviews, often referred to as 'stress tests', which reassessed safety margins of nuclear facilities with a primary focus on challenges related to conditions experienced at the Fukushima Daiichi nuclear power plant, for example extreme external events and the loss of safety functions, or capabilities to cope with severe accidents. As appropriate, improvements are being made to safety and emergency response systems to ensure that nuclear power plants are capable of withstanding events that lead to loss of electrical power and/or cooling capability. In the weeks following the accident, the NEA immediately began establishing expert groups in the nuclear safety and radiological protection areas, as well as contributing to information exchange with the Japanese authorities and other international organisations. It promptly provided a forum for high-level decision makers and regulators within the G8-G20 frameworks. The NEA actions taken at the international level in response to the accident have been carried out primarily by the three NEA standing technical committees concerned with nuclear and radiation safety issues - the Committee on Nuclear Regulatory Activities (CNRA), the Committee on the Safety of Nuclear Installations (CSNI) and the Committee on Radiation Protection and Public Health (CRPPH) - under the leadership of the CNRA. More than two years following the accident, the NEA continues to assist the Japanese authorities in dealing with their nuclear safety and recovery efforts as well as to facilitate international co-operation on nuclear safety and radiological protection matters. It is strongly supporting the establishment of

Heat and fluid flow in accident of Fukushima Daiichi Nuclear Power Plant, Unit 2. Accident scenario based on thermodynamic model

International Nuclear Information System (INIS)

Maruyama, Shigenao

2012-01-01

An accident scenario of Fukushima Daiichi Nuclear Power Plant, Unit 2 is analyzed from the data open to the public. Phase equilibrium process model was introduced that the vapor and water are at saturation point in the vessels. Proposed accident scenario agrees very well with the data of the plant parameters obtained just after the accident. The estimation describes that the rupture time of the reactor pressure vessel (RPV) was at 22:50 14/3/2011. The estimation shows that the rupture time of the pressure containment vessel (RCP) was at 7:40 15/3/2011. These estimations are different from the ones by TEPCO, however; many measured evidences show good accordance with the present scenario. (author)

Evaluation of short- and long-term fission product sources at the Fukushima Daiichi NPP

International Nuclear Information System (INIS)

Uchida, Shunsuke; Naitoh, Masanori; Suzuki, Hiroaki; Okada, Hidetoshi; Pellegrini, Marco; Achilli, Andrea; Hanamoto, Yukio; Sasaki, Hiroaki

2014-01-01

Research on fission product (FP) behaviors used to be one of the most important subjects in water chemistry but it is not done nowadays as a consequence of the increased integrity of nuclear fuels and the minimization of FP release into the environment. Evaluation of FP release into the environment is still one of the key issues for severe accident analysis, though. Although there have been a long quiet period in nuclear safety research, how to detect initiation of severe accidents, how to prevent them and how to mitigate them are still important subjects for nuclear engineering, and how to control the severe accidents after their occurrence, especially how to control FP release into the environment, has seldom been discussed in the water chemistry group recently. The paper is intended to address the issue of fewer activities for FP studies. FP sources are divided into two categories, short- and long-term FP sources. Short-term FP source can be evaluated based on the measured data obtained from monitoring posts (MPs), which give us clear evidence on the importance of radioactive iodine and cesium releases into the environment. It used to be considered that during primary containment vessel (PCV) venting, release of each element, e.g., iodine and cesium, was determined by the suppression pool scrubbing efficiency and most of the cesium would likely be removed in the pool due to its large scrubbing efficiency. But as a result of analyzing the MP data at early stage of the Fukushima Daiichi nuclear power plant (NPP) accident, it was confirmed that the releases of both elements were in proportion to their inventories in the reactors and their scrubbing efficiencies were almost the same. The scrubbing efficiency which increased with the pool water temperature became almost the same for iodine and cesium around the pool water boiling temperature. As a result of the mass balance analysis for FPs in the contaminated water accumulated in the Fukushima Daiichi plant site, it

Introduction of new terms and lessons for radiological protection after Fukushima Dai-Ichi accident

International Nuclear Information System (INIS)

Singh, Vishwanath P.; Managanvi, S.S.; Bhat, H.R.

2012-01-01

The nuclear accidents in the world are very few among various types of operating facilities. However when an accident happened, we have learnt a lot to improve the philosophy, term, definitions, document preparation, equipment's requirement, supporting systems, awareness program and restriction etc. After Fukushima Dai-ichi we have learnt a lot, in this view this paper has been prepared to discuss for radiological protection aspects. Discussion: The probability of nuclear accidents is negligible but when happens, it opens new doors of lessons for radiological protection practices for occupational workers, emergency workers for damage control to prevent catastrophic situation/rescue to life saving actions and the member of the public. The Chernobyl and Three Mile Island accidents have provided a lot experiences for management of emergency situations, documentation, radiation emergency preparedness, emergency equipment's, concept of defense-in-depth, emergency planning zone (EPZ), accidental dose limits, estimation of source term and public dose, intervention levels, decision supporting system, remedial actions in public domain; decontamination of person, houses/building and land and etc. Recent Fukushima Dai-ichi accident in Japan was managed in appreciable manner but still new definitions and lessons for radiological protection have been emerged out. The present paper discusses difficulties w. r. t. the radiological aspects observed/faced by Japanese during nuclear crises. The accident introduced new terms as Natural Dose Rate Unit (NDRU), voluntary evacuation, deliberate evacuation area, restricted area and difference between evacuation zone and EPZ. The Fukushima accident has enforced worldwide regulators and operators to review the individual dose limit and amendment for raise in the dose limit during accident, availability of efficient/adequate quantities of personal dosimeter in public domain, collection arrangement of bulk amount of radioactive wastes

Accumulation of radioactive cesium released from Fukushima Daiichi Nuclear Power Plant in terrestrial cyanobacteria Nostoc commune.

Science.gov (United States)

Sasaki, Hideaki; Shirato, Susumu; Tahara, Tomoya; Sato, Kenji; Takenaka, Hiroyuki

2013-01-01

The Fukushima Daiichi Nuclear Power Plant accident released large amounts of radioactive substances into the environment and contaminated the soil of Tohoku and Kanto districts in Japan. Removal of radioactive material from the environment is an urgent problem, and soil purification using plants is being considered. In this study, we investigated the ability of 12 seed plant species and a cyanobacterium to accumulate radioactive material. The plants did not accumulate radioactive material at high levels, but high accumulation was observed in the terrestrial cyanobacterium Nostoc commune. In Nihonmatsu City, Fukushima Prefecture, N. commune accumulated 415,000 Bq/kg dry weight (134)Cs and 607,000 Bq kg(-1) dry weight (137)Cs. The concentration of cesium in N. commune tended to be high in areas where soil radioactivity was high. A cultivation experiment confirmed that N. commune absorbed radioactive cesium from polluted soil. These data demonstrated that radiological absorption using N. commune might be suitable for decontaminating polluted soil.

A knowledge on environmental radiation monitoring about the influence from Fukushima Dai-ichi Nuclear Power accident

International Nuclear Information System (INIS)

Yoshioka, Mitsuo; Terakawa, Kazuyoshi; Kasai, Toshihiro

2012-01-01

A large amount of radioactive substances were released in the atmosphere and contaminated a large area across Japan due to the accident at Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company triggered by Great East Japan Earthquake and tsunami on May 11th 2011. At Fukui University of Technology, monitoring of air radiation (gamma ray) and radiation in environmental samples in Fukui prefecture and some areas of Fukushima prefecture were conducted in order to study the influence of radiation and radioactivity on the citizens as well as the perception of this study results by the citizens. Also, in order to study the dependency of the radiation influence on the distance from the accident location, radiation monitoring of fallouts (air-borne dust, rainwater, sediment mud, and so on) was conducted. In this article, the knowledge obtained on environmental radiation monitoring was summarized and reported. Especially, slightly modified dose-level evaluation for internal exposure was reported. (S.K.)

Probability of major depression diagnostic classification using semi-structured versus fully structured diagnostic interviews.

Science.gov (United States)

Levis, Brooke; Benedetti, Andrea; Riehm, Kira E; Saadat, Nazanin; Levis, Alexander W; Azar, Marleine; Rice, Danielle B; Chiovitti, Matthew J; Sanchez, Tatiana A; Cuijpers, Pim; Gilbody, Simon; Ioannidis, John P A; Kloda, Lorie A; McMillan, Dean; Patten, Scott B; Shrier, Ian; Steele, Russell J; Ziegelstein, Roy C; Akena, Dickens H; Arroll, Bruce; Ayalon, Liat; Baradaran, Hamid R; Baron, Murray; Beraldi, Anna; Bombardier, Charles H; Butterworth, Peter; Carter, Gregory; Chagas, Marcos H; Chan, Juliana C N; Cholera, Rushina; Chowdhary, Neerja; Clover, Kerrie; Conwell, Yeates; de Man-van Ginkel, Janneke M; Delgadillo, Jaime; Fann, Jesse R; Fischer, Felix H; Fischler, Benjamin; Fung, Daniel; Gelaye, Bizu; Goodyear-Smith, Felicity; Greeno, Catherine G; Hall, Brian J; Hambridge, John; Harrison, Patricia A; Hegerl, Ulrich; Hides, Leanne; Hobfoll, Stevan E; Hudson, Marie; Hyphantis, Thomas; Inagaki, Masatoshi; Ismail, Khalida; Jetté, Nathalie; Khamseh, Mohammad E; Kiely, Kim M; Lamers, Femke; Liu, Shen-Ing; Lotrakul, Manote; Loureiro, Sonia R; Löwe, Bernd; Marsh, Laura; McGuire, Anthony; Mohd Sidik, Sherina; Munhoz, Tiago N; Muramatsu, Kumiko; Osório, Flávia L; Patel, Vikram; Pence, Brian W; Persoons, Philippe; Picardi, Angelo; Rooney, Alasdair G; Santos, Iná S; Shaaban, Juwita; Sidebottom, Abbey; Simning, Adam; Stafford, Lesley; Sung, Sharon; Tan, Pei Lin Lynnette; Turner, Alyna; van der Feltz-Cornelis, Christina M; van Weert, Henk C; Vöhringer, Paul A; White, Jennifer; Whooley, Mary A; Winkley, Kirsty; Yamada, Mitsuhiko; Zhang, Yuying; Thombs, Brett D

2018-06-01

original sponsor of the development of the PHQ-9, which is now in the public domain. Dr Chan is a steering committee member or consultant of Astra Zeneca, Bayer, Lilly, MSD and Pfizer. She has received sponsorships and honorarium for giving lectures and providing consultancy and her affiliated institution has received research grants from these companies. Dr Hegerl declares that within the past 3 years, he was an advisory board member for Lundbeck, Servier and Otsuka Pharma; a consultant for Bayer Pharma; and a speaker for Medice Arzneimittel, Novartis, and Roche Pharma, all outside the submitted work. Dr Inagaki declares that he has received grants from Novartis Pharma, lecture fees from Pfizer, Mochida, Shionogi, Sumitomo Dainippon Pharma, Daiichi-Sankyo, Meiji Seika and Takeda, and royalties from Nippon Hyoron Sha, Nanzando, Seiwa Shoten, Igaku-shoin and Technomics, all outside of the submitted work. Dr Yamada reports personal fees from Meiji Seika Pharma Co., Ltd., MSD K.K., Asahi Kasei Pharma Corporation, Seishin Shobo, Seiwa Shoten Co., Ltd., Igaku-shoin Ltd., Chugai Igakusha and Sentan Igakusha, all outside the submitted work. All other authors declare no competing interests. No funder had any role in the design and conduct of the study; collection, management, analysis and interpretation of the data; preparation, review or approval of the manuscript; and decision to submit the manuscript for publication.

Development of remote decontamination technologies improving internal environment of reactor buildings at Fukushima Daiichi Nuclear Power Station

International Nuclear Information System (INIS)

Hotta, Koji; Hayashi, Hirotada; Sakai, Hitoshi

2016-01-01

The reactor buildings at the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc., which was seriously damaged by the Great East Japan Earthquake of March 11, 2011, have been highly contaminated by radioactive materials. To safely and efficiently advance the processes related to the forthcoming decommissioning of the reactors, it is necessary to improve the hazardous environment inside the reactor buildings. During the more than four years that have elapsed since the Great East Japan Earthquake, Toshiba has been implementing various measures to reduce the ambient dose rates inside the reactor buildings through decontamination work and participation in a national project for the development of remote decontamination technologies for reactor buildings. A variety of vehicles and technologies to support decontamination work have been developed through these activities, and are significantly contributing to improvement of the environment inside the reactor buildings. (author)

Risk communication with Fukushima residents affected by the Fukushima Daiichi accident at whole-body counting

Energy Technology Data Exchange (ETDEWEB)

Gunji, I.; Furuno, A.; Yonezawa, R.; Sugiyama, K. [Risk Communication Study Office, Japan Atomic Energy Agency 4-33 Muramatsu, Tokai-mura, Ibaraki, 319-1194 (Japan)

2013-07-01

After the Tokyo Electric Power Company (TEPCO) Fukushima Daiichi nuclear power plant accident, the Tokai Research and Development Center of the Japan Atomic Energy Agency (JAEA) have had direct dialogue as risk communication with Fukushima residents who underwent whole-body counting examination (WBC). The purpose of the risk communication was to exchange information and opinions about radiation in order to mitigate Fukushima residents' anxiety and stress. Two kinds of opinion surveys were performed: one survey evaluated residents' views of the nuclear accident itself and the second survey evaluated the management of WBC examination as well as the quality of JAEA's communication skills on risks. It appears that most Fukushima residents seem to have reduced their anxiety level after the direct dialogue. The results of the surveys show that Fukushima residents have the deepest anxiety and concern about their long-term health issues and that they harbor anger toward the government and TEPCO. On the other hand, many WBC patients and patients' relatives have expressed gratitude for help in reducing their feelings of anxiety.

Direction on characterization of fuel debris for defueling process in Fukushima Daiichi Nuclear Power Station

International Nuclear Information System (INIS)

Yano, Kimihiko; Kitagaki, Toru; Ikeuchi, Hirotomo; Wakui, Ryohei; Higuchi, Hidetoshi; Kaji, Naoya; Koizumi, Kenji; Washiya, Tadahiro

2013-01-01

For the decommissioning of Fukushima Daiichi Nuclear Power Station (1F), defueling of the fuel debris in the reactor core of Units 1-3 is planned to start within 10 years. Preferential items in the characterization of the fuel debris were identified for this work, in which the procedure and handling tools were assumed on the basis of information on 1F and experience after the Three Mile Island Unit 2 (TMI-2) accident. The candidates for defueling tools for 1F were selected from among the TMI- 2 defueling tools. It was found that they could be categorized into six groups according to their operating principles. The important properties of the fuel debris for defueling were selected considering the effect of the target materials on the tool performance. The selected properties are shape, size, density, thermal conductivity, heat capacity, melting point, hardness, elastic modulus, and fracture toughness. Of these properties, the mechanical properties (hardness, elastic modulus, fracture toughness) were identified as preferential items, because too few data on these characteristics of fuel debris are available in past severe accident studies. (authors)

Screening survey on thyroid exposure for children after the Fukushima Daiichi Nuclear Power Station accident

Energy Technology Data Exchange (ETDEWEB)

Kim, Eunjoo; Kurihara, Osamu; Suzuki, Toshikazu; Matsumoto, Masaki; Fukutsu, Kumiko; Yamada, Yuji; Sugiura, Nobuyuki; Akashi, Makoto [National Institute of Radiological Sciences, Research Center for Radiation Emergency Medicine, Chiba, Chiba (Japan)

2012-11-15

In response to a serious accident at the Fukushima Daiichi Nuclear Power Station, National Institute of Radiological Sciences (NIRS) established a protocol for a screening survey of thyroid exposure for children living in areas where thyroid doses were predicted to be high. The aim of the screening survey was to implement measurements for a large number of subjects with conventional NaI(Tl) scintillation survey meters. This protocol was applied to the screening survey of 1,149 children at five locations in three municipalities (Kawamata Town, Iitate Village and Iwaki City). Among 1,080 children (excluding 69 subjects from evaluation), there were no subjects who exceeded a screening level (0.2 {mu}Sv h{sup -1}) corresponding to a thyroid equivalent dose of 100 mSv (for the age group of 1-y-old as of March 24). No significant signals were detected in 55.4% of these subjects and the maximum dose was found to be 43 mSv. This paper presents details on the protocol as well as results of the screening survey. (author)

Risk communication with Fukushima residents affected by the Fukushima Daiichi accident at whole-body counting

International Nuclear Information System (INIS)

Gunji, I.; Furuno, A.; Yonezawa, R.; Sugiyama, K.

2013-01-01

After the Tokyo Electric Power Company (TEPCO) Fukushima Daiichi nuclear power plant accident, the Tokai Research and Development Center of the Japan Atomic Energy Agency (JAEA) have had direct dialogue as risk communication with Fukushima residents who underwent whole-body counting examination (WBC). The purpose of the risk communication was to exchange information and opinions about radiation in order to mitigate Fukushima residents' anxiety and stress. Two kinds of opinion surveys were performed: one survey evaluated residents' views of the nuclear accident itself and the second survey evaluated the management of WBC examination as well as the quality of JAEA's communication skills on risks. It appears that most Fukushima residents seem to have reduced their anxiety level after the direct dialogue. The results of the surveys show that Fukushima residents have the deepest anxiety and concern about their long-term health issues and that they harbor anger toward the government and TEPCO. On the other hand, many WBC patients and patients' relatives have expressed gratitude for help in reducing their feelings of anxiety

Case study of medical evacuation before and after the Fukushima Daiichi nuclear power plant accident in the great east Japan earthquake.

Science.gov (United States)

Okumura, Tetsu; Tokuno, Shinichi

2015-01-01

In Japan, participants in the disaster-specific medical transportation system have received ongoing training since 2002, incorporating lessons learned from the Great Hanshin Earthquake. The Great East Japan Earthquake occurred on March 11, 2011, and the very first disaster-specific medical transport was performed. This article reviews in detail the central government's control and coordination of the disaster medical transportation process following the Great East Japan Earthquake and the Fukushima Daiichi Nuclear Power Plant Accident. In total, 124 patients were air transported under the coordination of the C5 team in the emergency response headquarter of the Japanese Government. C5 includes experts from the Cabinet Office, Cabinet Secretariat, Fire Defense Agency, Ministry of Health, Labour and Welfare, and Ministry of Defense. In the 20-30 km evacuation zone around the Fukushima Daiichi nuclear power plant, 509 bedridden patients were successfully evacuated without any fatalities during transportation. Many lessons have been learned in disaster-specific medical transportation. The national government, local government, police, and fire agencies have made significant progress in their mutual communication and collaboration. Fortunately, hospital evacuation from the 20-30 km area was successfully performed with the aid of local emergency physicians and Disaster Medical Assistance Teams (DMATs) who have vast experience in patient transport in the course of day-to-day activities. The emergency procedures that are required during crises are an extension of basic daily procedures that are performed by emergency medical staff and first responders, such as fire fighters, emergency medical technicians, or police officers. Medical facilities including nursing homes should have a plan for long-distance (over 100 km) evacuation, and the plan should be routinely reevaluated with full-scale exercises. In addition, hospital evacuation in disaster settings should be

Supportive measures toward safety assurance of post-disaster Fukushima Daiichi Nuclear Power Plant

International Nuclear Information System (INIS)

Hatazawa, Mamoru

2012-01-01

Toshiba group had taken supportive measures toward safety assurance of post-disaster Fukushima Daiichi Nuclear Power Plant, such as active water treatment, upgrade core cooling capability with additional water injection rout of core spray spargers, alternative cooling system of spent fuel pool with air cooler and nitrogen injection into reactor containment vessel from portable air separation system for nitrogen generation. As for a water treatment system for handling the radioactive water that had built up in the basement of the turbine building from injected water for cooling fuel debris, it was implemented at first by water treatment equipment from Areva and Kurion and now by Simplified Active Water Retrieve and Recovery System (SARRY) which Toshiba had newly developed as redundant system. Purified water could be reused for circulating injected water for reactor cooling. Strenuous efforts would be made for installation of cover building for fuel removal from spent fuel pool of unit 3 reactor and technology development for fuel debris removal using remote control robots. Portable gamma camera had been developed for decontamination works of radiation 'hot spot'. With loading SARRY on truck, mobile contaminated water treatment and contaminated soil purification system using oxalic acid solution for cesium extraction had been developed to contribute environmental remedial action in surrounding areas. (T. Tanaka)

Atmospheric radionuclides from the Fukushima Dai-ichi nuclear reactor accident observed in Vietnam

International Nuclear Information System (INIS)

Long, N.Q.; Giap, T.V.; Phan, N.T.; Truong, Y.; Binh, N.T; Sieu, L.N.; Hien, P.D.

2012-01-01

Radionuclides from the reactor accident at the Fukushima Dai-ichi Nuclear Power Plant were observed in the surface air at stations in Hanoi, Dalat and Ho Chi Minh City (HCMC) in Vietnam, about 4500 km southwest of Japan, during the period from March 27 to April 22, 2011. The maximum activity concentrations in the air measured at those three sites were 193, 33 and 37 μBq m -3 for 131 I, 134 Cs and 137 Cs, respectively. Peaks of radionuclide concentrations in the air corresponded to arrival of the air mass from Fukushima to Vietnam after traveling for 8 days over the Pacific Ocean. Cesium-134 was detected with the 134 Cs/ 137 Cs activity ratio of about 0.85 in line with observations made elsewhere. The 131 I/ 137 Cs activity ratio was observed to decrease exponentially with time as expected from radioactive decay. The ratio at Dalat, where is 1500 m high, was higher than those at Hanoi and HCMC in low lands, indicating the relative enrichment of the iodine in comparison to cesium at high altitudes. The time-integrated surface air concentrations of the Fukushima-derived radionuclides in the Southeast Asia showed exponential decrease with distance from Fukushima. (author)

¹²⁹I and ¹³⁷Cs in groundwater in the vicinity of Fukushima Dai-ichi nuclear power plant

DEFF Research Database (Denmark)

Xu, Sheng; Zhang, Luyuan; Freeman, Stewart P.H.T.

2016-01-01

. The minimal 129I/137Cs activity ratios in the groundwater are more than 2–500 times higher than the FDNPP source ratio. These data can be explained by rainwater infiltrating through the surface soils, with the more water-soluble 129I preferentially extracted into the aqueous phase and the 137Cs preferentially......This paper reports iodine (127I and 129I) and cesium (137Cs) isotope concentrations in groundwater of confined and unconfined aquifers in the vicinity of the Fukushima Dai-ichi nuclear power plant (FDNPP). 127I and 129I concentrations range from 2–13 μg/L and 5 × 107–8 × 1010 atom/L respectively...... retained in the soil....

Framing the Fukushima Daiichi nuclear accident: An international, comparative study of news frames in Der Spiegel, the Japan Times and the Los Angeles Times

International Nuclear Information System (INIS)

Giannakopoulos, Thanos

2013-01-01

This study investigated into the news frames employed in reporting on the Fukushima Daiichi nuclear accident, explored the maintenance of the radiation reporting standard, and assessed the overall tone for the local government, the Japanese Government, and the IAEA. Based on content from Der Spiegel, the Japan Times and the Los Angeles Times (n=60), it was found that media evoked 'conflict', 'responsibility attribution', and 'human interest' frames, radiation reporting standard was marginally maintained, and the overall tone was neutral (local government, IAEA) or negative (Japanese Government). Variances across countries were observed, but results coincided with the country's nuclear energy policy. (author)

The Follow-up IAEA International Mission on Remediation of Large Contaminated Areas Off-Site the Fukushima Daiichi Nuclear Power Plant, Tokyo and Fukushima Prefecture, Japan, 14-21 October 2013. Final Report

International Nuclear Information System (INIS)

2014-01-01

In October 2011, the IAEA conducted an International Mission to Japan to support the remediation of large contaminated areas off-site TEPCO's Fukushima Daiichi Nuclear Power Plant (NPP). In response to the request made by the Government of Japan, in October 2013, the IAEA organized a follow-up International Mission on remediation of large contaminated areas off-site TEPCO's Fukushima Daiichi NPP (hereinafter referred to as the 'Follow-up Mission' or the 'Mission') with the main purpose of evaluating the progress of the on-going remediation works achieved since the previous mission in October 2011. The Follow-up Mission Team involved 13 international experts. Additionally, 3 experts of the Working Group 5 (Subgroup 5.2, Remediation) in charge of preparing the IAEA Report on TEPCO Fukushima Daiichi Accident accompanied the Mission as observers to obtain first-hand information for the report. The Follow-up Mission had the following three objectives: 1. To provide assistance to Japan in assessing the progress made with the remediation of the Special Decontamination Area (not included in the previous mission of 2011) and the Intensive Contamination Survey Areas; 2. To review remediation strategies, plans and works, in view of the advice provided by the previous mission on remediation of large contaminated off-site areas; and 3. To share its findings with the international community as lessons learned. The Mission was conducted through the assessment of information provided to the Team and by means of professional and open discussions with the relevant institutions in Japan, including national, prefectural and local institutions. The Japanese authorities provided comprehensive information on their remediation programme. The Mission Team visited the affected areas, including several sites where activities on remediation were conducted. The Team also visited some temporary storage sites for radioactive waste and soil generated in the remediation activities, as well as a

Thyroid equivalent doses due to radioiodine-131 intake for evacuees from Fukushima Daiichi Nuclear Power Plant accident

Energy Technology Data Exchange (ETDEWEB)

Tokonami, Shinji; Sorimachi, Atsuyuki; Kashiwakura, Ikuo [Hirosaki University, Institute of Radiation Emergency Medicine, Hirosaki, Aomori (Japan); Hosoda, Masahiro [Hirosaki University, Graduate School of Health Sciences, Hirosaki, Aomori (Japan); Akiba, Suminori [Kagoshima University, Graduate School of Medical and Dental Sciences, Kagoshima (Japan); Balonov, Mikhail [Protection Laboratory, Institute of Radiation Hygiene, Petersburg (Russian Federation)

2012-11-15

A primary health concern among residents and evacuees in affected areas immediately after a nuclear accident is the internal exposure of the thyroid to radioiodine, particularly I-131, and subsequent thyroid cancer risk. In Japan, the natural disasters of the earthquake and tsunami in March 2011 destroyed an important function of the Fukushima Daiichi Nuclear Power Plant (F1-NPP) and a large amount of radioactive material was released to the environment. Here we report for the first time extensive measurements of the exposure to I-131 revealing I-131 activity in the thyroid of 46 out of the 62 residents and evacuees measured. The median thyroid equivalent dose was estimated to be 4.2 mSv and 3.5 mSv for children and adults, respectively, much smaller than the mean thyroid dose in the Chernobyl accident (490 mSv in evacuees). Maximum thyroid doses for children and adults were 23 mSv and 33 mSv, respectively. (author)

Perceived Workplace Interpersonal Support Among Workers of the Fukushima Daiichi Nuclear Power Plants Following the 2011 Accident: The Fukushima Nuclear Energy Workers' Support (NEWS) Project Study.

Science.gov (United States)

Takahashi, Sho; Shigemura, Jun; Takahashi, Yoshitomo; Nomura, Soichiro; Yoshino, Aihide; Tanigawa, Takeshi

2017-10-10

The 2011 Fukushima Daiichi nuclear accident was the worst nuclear disaster since Chernobyl. The Daiichi workers faced multiple stressors (workplace trauma, victim experiences, and public criticism deriving from their company's post-disaster management). Literatures suggest the importance of workplace interpersonal support (WIS) in enhancing psychological health among disaster workers. We sought to elucidate the role of their demographics, disaster-related experiences, and post-traumatic stress symptoms on perceived WIS. We analyzed self-report questionnaires of 885 workers 2-3 months post-disaster. We used sociodemographic and disaster exposure-related variables and post-traumatic stress symptoms (measured by the Impact of Event Scale-Revised) as independent variables. We asked whether WIS from colleagues, supervisors, or subordinates was perceived as helpful, and used yes or no responses as a dependent variable. Logistic regression analyses were performed to assess correlates of WIS. Of the participants, one-third (34.7%) reported WIS. WIS was associated with younger age (20-28 years [vs 49-], adjusted odds ratio [aOR]: 3.25, 95% CI: 1.99-5.32), supervisory work status (aOR: 2.30, 95% CI: 1.35-3.92), and discrimination or slur experience (aOR: 1.65, 95% CI: 1.08-2.53). Educational programs focusing on WIS might be beneficial to promote psychological well-being among nuclear disaster workers, especially younger workers, supervisors, and workers with discrimination experiences. (Disaster Med Public Health Preparedness. 2017; page 1 of 4).

Current understanding of the sequence of events. Overview of current understanding of accident progression at Fukushima Dai-ichi

International Nuclear Information System (INIS)

Gulliford, Jim

2013-01-01

An overview of the main sequence of events, particularly the evolution of the cores in Units 1-3 was given. The presentation is based on information provided by Dr Okajima of JAEA to the June 2012 Nuclear Science Committee meeting. During the accident, conditions at the plant were such that operators were initially unable to obtain instruments readouts from the control panel and hence could not know what condition the reactors were in. (Reactor Power, Pressure, Temperature, Water height and flow rate, etc.). Subsequently, as electrical power supplies were gradually restored more data became available. In addition to the reactor data, other information from off-site measurements and from measuring stations inside the site boundary is now available, particularly for radiation dose rates in air. These types of information, combined with detailed knowledge of the plant design and operations history up to the time of the accident are being used to construct detailed computer models which simulate the behaviour of the reactor core, pressure vessel and containment during the accident sequence. This combination of detailed design/operating data, limited measured data during the accident and computer modelling allows us to construct a fairly clear picture of the accident progression. The main sequence of events (common to Units 1, 2 and 3) is summarised. The OECD/NEA is currently coordinating an international benchmark study of the accident at Fukushima Daiichi known as the BSAF Project. The objectives of this activity are to analyse and evaluate the accident progression and improve severe accident (SA) analysis methods and models. The project provides valuable additional (and corrected) data from plant measurements as well as an improved understanding of the role played by the fuel and cladding design. Based on (limited) plant data and extensive modelling analysis, we have a detailed qualitative description of the Fukushima-Daiichi accident. Further analyses of the type

Life as an evacuee after the Fukushima Daiichi nuclear power plant accident is a cause of polycythemia: the Fukushima Health Management Survey.

Science.gov (United States)

Sakai, Akira; Ohira, Tetsuya; Hosoya, Mitsuaki; Ohtsuru, Akira; Satoh, Hiroaki; Kawasaki, Yukihiko; Suzuki, Hitoshi; Takahashi, Atsushi; Kobashi, Gen; Ozasa, Kotaro; Yasumura, Seiji; Yamashita, Shunichi; Kamiya, Kenji; Abe, Masafumi

2014-12-23

The Great East Japan Earthquake and the Fukushima Daiichi nuclear disaster forced people to evacuate their hometowns. Many evacuees from the government-designated evacuation zone were forced to change their lifestyle, diet, exercise, and other personal habits. The Comprehensive Health Check (CHC), 1 of 4 detailed surveys of The Fukushima Health Management Survey (FHMS), was implemented to support the prevention of lifestyle-related disease. The aim of this study was to analyze changes in red blood cell count (RBC), hemoglobin (Hb) levels, and hematocrit (Ht) levels by comparing data from the medical health checkup before and after the disaster in individuals who were 40 years old or older. Subjects in this study were Japanese men and women living in the vicinity of the Fukushima Daiichi Nuclear Power Plant in Fukushima prefecture. Annual health checkups with a focus on metabolic syndrome for insured persons/dependents aged 40 or older by Health Care Insurers have been conducted since 2008. All analyses in this study were limited to men and women aged 40-90 years. Changes in RBC, Hb levels, Ht levels, and prevalence of polycythemia before and after the disaster were compared. First, RBC, Hb, and Ht significantly increased in both men and women evacuees. The evacuation was significantly associated with increased Hb levels after adjustment for age, gender, smoking status, excess ethanol intake, BMI, and baseline Hb level (β = 0.16, p < 0.001). Furthermore, the prevalence of polycythemia stratified by smoking status or obesity also increased in the evacuee group. To our knowledge, this is the first report revealing that the evacuation was associated with the risk of polycythemia. This information could be very important for periodic health checkup and lifestyle recommendations for evacuees in the future.

NEA and its Role in Enhancing the Implementation of Defence in Depth (DiD) in Light of the Fukushima Dai-ichi Accident

Energy Technology Data Exchange (ETDEWEB)

Shimomura, K., E-mail: Kazuo.SHIMOMURA@oecd.org [OECD Nuclear Energy Agency (NEA), Issy-Les-Moulineaux (France)

2014-10-15

Full text: This keynote speech will give an overview of NEA Activities to Enhance Global Nuclear Safety both those core to its work and those that have been initiated after the Fukushima Accident. In particular it will highlight the outcomes of the recently published “NEA report on the Fukushima Daiichi Nuclear Power Plant Accident”. The speech will specifically point out those lessons learnt related to Defence in Depth, and how those were fed into the NEA’s one day workshop on “Challenges and Enhancements to DiD in light of the Fukushima Dai-ichi Accident”, that took place on 5th June 2013. A workshop that brought together the member countries represented on the NEA’s three major standing committees for safety to not only discuss the lessons learnt from the accident but also what the NEA members considered could be done to enhance the understanding and implementation of defence in depth within nuclear safety. Members of these three standing committees, the Committee for Nuclear Regulatory Activities (CNRA), The Committee for Safety of Nuclear Installations (CSNI) and the Committee on Radiation Protection and Public Health (CRPPH) represent a considerable body of knowledge on the application of DiD within the countries using nuclear energy. The outcome of the workshop was the identification of a number of key tasks that NEA would take forward to assist in harmonising and enhancing globally the implementation of the DiD philosophy. The speech will in addition detail how the discussions ranged across the whole of the nuclear safety framework, what conclusions were derived and the process the NEA followed to incorporate those tasks within its future programme of work either by enhancing current activities or creating new ones. (author)

Isotopic ratio and vertical distribution of radionuclides in soil affected by the accident of Fukushima Dai-ichi nuclear power plants

International Nuclear Information System (INIS)

Fujiwara, Takeshi; Saito, Takumi; Muroya, Yusa; Sawahata, Hiroyuki; Yamashita, Yuji; Nagasaki, Shinya; Okamoto, Koji; Takahashi, Hiroyuki; Uesaka, Mitsuru; Katsumura, Yosuke; Tanaka, Satoru

2012-01-01

The results of γ analyses of soil samples obtained from 50 locations in Fukushima prefecture on April 20, 2011, revealed the presence of a spectrum of radionuclides resulted from the accident of the Fukushima Dai-ichi nuclear power plant (FDNPP). The sum γ radioactivity concentration ranged in more than 3 orders of magnitude, depending on the sampling locations. The contamination of soils in the northwest of the FDNPP was considerable. The 131 I/ 137 Cs activity ratios of the soil samples plotted as a function of the distance from the F1 NPPs exhibited three distinctive patterns. Such patterns would reflect not only the different deposition behaviors of these radionuclides, but also on the conditions of associated release events such as temperature and compositions and physicochemical forms of released radionuclides. The 136 Cs/ 137 Cs activity ratio, on the other hand, was considered to only reflect the difference in isotopic compositions of source materials. Two locations close to the NPP in the northwest direction were found to be depleted in short-lived 136 Cs. This likely suggested the presence of distinct sources with different 136 Cs/ 137 Cs isotopic ratios, although their details were unknown at present. Vertical γ activity profiles of 131 I and 137 Cs were also investigated, using 20–30 cm soil cores in several locations. About 70% or more of the radionuclides were present in the uppermost 2-cm regions. It was found that the profiles of 131 I/ 137 Cs activity ratios showed maxima in the 2–4 cm regions, suggesting slightly larger migration of the former nuclide. - Highlights: ► We report the results of γ analyses of soil samples around Fukushima Dai-ichi NPPs. ► The contamination of soils in the northwest of the power plant was considerable. ► The 131 I/ 137 Cs activity ratios exhibited three distinctive patterns. ► Most of 131 I and 137 Cs were present in the uppermost 2-cm regions of soil.

14C levels in the vicinity of the Fukushima Dai-ichi Nuclear Power Plant prior to the 2011 accident

DEFF Research Database (Denmark)

Xu, Sheng; Cook, Gordon T.; Cresswell, Alan J.

2016-01-01

A 50-year-old Japanese cedar (Cryptomeria japonica) from Okuma, ∼1 km southwest of the Fukushima Dai-ichi Nuclear Power Plant, was cored and each annual ring was analysed for 14C. The 14C specific activity values varied from 330.4 Bq kg−1 C in the tree ring formed in 1971 to 231.2 Bq kg−1 C...... discharges from the reactors during their normal operations. In addition, the specific activities are positively correlated with the annual electricity generation values. The excess 14C specific activities were effective dose of ... ingestion pathway in the study location. The primary wind direction is east-southeast/southeast with a frequency of ∼30%, in comparison to ∼20% frequency for the direction of the site under study (north-northeast/northeast). This would tend to indicate a similar magnitude of additional effective dose...

Local area distribution of fallout radionuclides from Fukushima Daiichi Nuclear Power Plant determined by autoradiography analysis

International Nuclear Information System (INIS)

Sakamoto, Fuminori; Ohnuki, Toshihiko; Kozai, Naofumi; Igarashi, Shosuke; Yamasaki, Shinya; Yoshida, Zenko; Tanaka, Shunichi

2012-01-01

The environmental behavior of radioactive Cs in the fallout from the accident of the Fukushima Daiichi Nuclear Power Plant has been studied by measuring its spatial distribution on/in trees, plants, and surface soil beneath the plants using autoradiography analysis. The results of autoradiography analysis showed that radioactive Cs was distributed on the branches and leaves of trees that were present during the accident and that only a small fraction of radioactive Cs was transported to new branches and leaves grown after the accident. Radioactive Cs was present on the grass and rice stubble on the soils, but not in the soils beneath the grass and rice stubble, indicating that the radioactive Cs was deposited on the grass and the rice plant. In addition, the ratio of the radioactive Cs that penetrated into the soil layer by weathering was very small two months after the accident. These results indicate that trees and other plants are the reservoir of the fallout Cs and function to retard the fallout Cs migration with rain water. (author)

National radiological emergency response to the Fukushima Daiichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Dela Rosa, Alumanda M.

2011-01-01

The Fukushima nuclear power plant accident occurred on March 11, 2011, when two natural disasters of unprecedented strengths, an earthquake with magnitude 9 followed one hour later by a powerful tsunami struck northeastern Japan and felled the external power supply and the emergency diesel generators of the Fukushima Daiichi nuclear power station, resulting in a loss of coolant accident. There were core meltdowns in three nuclear reactors with the release of radioactivity estimated to be 1/10 of what was released to the environment during the Chernobyl nuclear power plant accident in April 1986. The Fukushima nuclear accident tested the capability of the Philippine Nuclear Research Institute (PNRI) and the National Disaster Risk Reduction and Management Council (NDRRMC) in responding to such radiological emergency as a nuclear power plant accident. The PNRI and NDRRMC activated the RADPLAN for possible radiological emergency. The emergency response was calibrated to the status of the nuclear reactors on site and the environmental monitoring undertaken around the site and off-site, including the marine environment. This orchestrated effort enabled the PNRI and the national agencies concerned to reassure the public that the nuclear accident does not have a significant impact on the Philippines, both on the health and safety of the people and on the safety of the environment. National actions taken during the accident will be presented. The role played by the International Atomic Energy Agency as the central UN agency for nuclear matters will be discussed. (author)

Performance of Panasonic ZP-1460 Electronic Personal Dosemeter under Exposure Conditions Likely to be Found at Fukushima Daiichi Nuclear Power Plant

Science.gov (United States)

Tsujimura, Norio; Yoshida, Tadayoshi; Hoshi, Katsuya; Momose, Takumaro

A study on the performance of the Panasonic ZP-1460 electronic personal dosemeter, the model used in the aftermath of the Fukushima Daiichi nuclear power plant accident in March 2011, was conducted under actual exposure situations likely encountered in the plant. The tests pertained to (1) the dose rate response over dose rates >100 mSv/h and (2) the angular response on an anthropomorphic phantom exposed to the rotational and isotropic irradiation geometries. The test results confirmed that the dosemeter provides Hp(10) as a reasonably close estimate of the effective dose for any exposure geometries. The dosemeter response data evaluated in this study can be utilized for converting dosemeter readings to the absorbed dose to any organs and tissues for epidemiologic purposes.

Remediation of radiocesium-contaminated liquid waste, soil, and ash: a mini review since the Fukushima Daiichi Nuclear Power Plant accident.

Science.gov (United States)

Ding, Dahu; Zhang, Zhenya; Lei, Zhongfang; Yang, Yingnan; Cai, Tianming

2016-02-01

The radiation contamination after the Fukushima Daiichi Nuclear Power Plant accident attracts considerable concern all over the world. Many countries, areas, and oceans are greatly affected by the emergency situation other than Japan. An effective remediation strategy is in a highly urgent demand. Though plenty of works have been carried out, progressive achievements have not yet been well summarized. Here, we review the recent advances on the remediation of radiocesium-contaminated liquid waste, soil, and ash. The overview of the radiation contamination is firstly given. Afterwards, the current remediation strategies are critically reviewed in terms of the environmental medium. Special attentions are paid on the adsorption/ion exchange and electrically switched ion exchange methods. Finally, the present review outlines the possible works to do for the large-scale application of the novel remediation strategies.

Analysis of gamma ray intensity on the S/C vent pipes area in the unit 2 reactor building of the Fukushima Daiichi Nuclear Power Plant

Energy Technology Data Exchange (ETDEWEB)

Cho, Jai Wan; Choi, Young Soo; Jeong, Kyung Min [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

The robot is equipped with cameras, a dosimeter, and 2 DOF (degree of freedom) manipulation arms. It loads a small vehicle equipped with a camera that can access and inspect narrow areas. TEPCO is using the four-legged walking robot to inspect the suppression chamber (S/C) area of the unit 2 reactor building basement in the Fukushima Daiichi Nuclear Power Plant. The robot carried out 6 missions for about four months, from 11 December, 2012 to 15 March, 2013, where it examined an evidence of a leakage of radioactivity contaminated water in the S/C area of unit 2 reactor building. When a camera's signal processing unit, which is consist of ASIC and FPGA devices manufactured by a CMOS fabrication process, is exposed to a higher dose rate gamma ray, the speckle distribution in the camera image increase more. From the inspection videos, released by TEPCO, of the underground 8 vent pipes in the unit 2 reactor building, we analyzed the speckle distribution from the high dose-rate gamma rays. Based on the distribution of the speckle, we attempted to characterize the vent pipe with much radioactivity contaminated materials among the eight vent pipes connected to the PCV. The numbers of speckles viewed in the image of a CCD (or CMOS) camera are related to an intensity of the gamma ray energy emitted by a nuclear fission reaction from radioactivity materials. The numbers of speckles generated by gamma ray irradiation in the camera image are calculated by an image processing technique. Therefore, calculating the speckles counts, we can determine the vent pipe with relatively most radioactivity-contaminated materials among the other vent pipes. From the comparison of speckles counts calculated in the inspection image of the vent pipe with the speckles counts extracted by gamma ray irradiation experiment of the same small vehicle camera model loaded with the four-legged walking robot, we can qualitatively estimate the gamma ray dose-rate in the S/C vent pipe area of the

Linear free energy correlations for fission product release from the Fukushima-Daiichi nuclear accident.

Science.gov (United States)

Abrecht, David G; Schwantes, Jon M

2015-03-03

This paper extends the preliminary linear free energy correlations for radionuclide release performed by Schwantes et al., following the Fukushima-Daiichi Nuclear Power Plant accident. Through evaluations of the molar fractionations of radionuclides deposited in the soil relative to modeled radionuclide inventories, we confirm the initial source of the radionuclides to the environment to be from active reactors rather than the spent fuel pool. Linear correlations of the form In χ = −α ((ΔGrxn°(TC))/(RTC)) + β were obtained between the deposited concentrations, and the reduction potentials of the fission product oxide species using multiple reduction schemes to calculate ΔG°rxn (TC). These models allowed an estimate of the upper bound for the reactor temperatures of TC between 2015 and 2060 K, providing insight into the limiting factors to vaporization and release of fission products during the reactor accident. Estimates of the release of medium-lived fission products 90Sr, 121mSn, 147Pm, 144Ce, 152Eu, 154Eu, 155Eu, and 151Sm through atmospheric venting during the first month following the accident were obtained, indicating that large quantities of 90Sr and radioactive lanthanides were likely to remain in the damaged reactor cores.

Teaching of severe accident of Fukushima Daiichi Nuclear Power Plants of Tokyo Electric Power

International Nuclear Information System (INIS)

Saito, Shinzo

2011-01-01

The Great East Japan Earthquake and accompanied tsunami brought about the severe accident at Fukushima Daiichi Nuclear Power Plants of Tokyo Electric Power Co., Inc. For 'No more Fukushima', twelve teaching of the accident was pointed out as follows: 1) natural disasters and external events shall be taken into consideration, 2) severe accident shall be included into safety regulation, 3) all possibility of hydrogen explosion shall be excluded, 4) diversity of safety important component and equipment shall be added with sufficient period of outage, 5) siting of multiple units at the same site shall be avoided at quake-prone country like Japan, 6) accident response environment for operators shall be improved, 7) accident convergence termination system shall be established so as to concentrate technical experience and knowledge, 8) off-site center shall be improved, 9) resident evacuation, consumption limit of food, radiation exposure and soil contamination limit shall be decided openly, 10) nuclear regulation and prevention of disaster shall be conducted by unitary organization to gain public trust, 11) fostering of safety culture among relevant enterprises shall be more encouraged and 12) nuclear industry shall develop reactor such as with no core meltdown or no evacuation and environmental contamination even if reactor core would be meltdown. (T. Tanaka)

Investigating plutonium contamination in marine sediments off Fukushima coast following the Fukushima Dai-ichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Bu Wenting; Guo Qiuju; Zheng, Jian; Aono, Tatsuo; Tagami, Keiko; Uchida, Shigeo; Zhang, Jing; Yamada, Masatoshi

2013-01-01

The Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident has caused large amounts of anthropogenic radionuclides to be released into the atmosphere as well as directly discharged into the sea. To obtain the vertical distribution of Pu isotopes in marine sediments and to better assess the possible contamination from the FDNPP accident in the marine environment, activities of "2"3"9"+"2"4"0Pu and "2"4"1Pu, as well as the atom ratios of "2"4"0Pu/"2"3"9Pu and "2"4"1Pu/"2"3"9Pu, were investigated in a sediment core collected from the western North Pacific in July 2011. The observed vertical profile of "2"3"9"+"2"4"0Pu activities and "2"4"0Pu/"2"3"9Pu atom ratios showed no extra injection of Pu from the accident, indicating no immediate Pu contamination from the FDNPP accident in the marine sediments in the region investigated. (author)

Impact on the marine environment of radioactive releases resulting from the Fukushima-Daiichi nuclear accident. April 4, 2011

International Nuclear Information System (INIS)

2011-01-01

After having outlined that measurements taken over several days in the sea water in the vicinity of the power station have revealed severe contamination of the marine environment by various radionuclides released as a result of the accident at the Fukushima-Daiichi nuclear power station, this report describes the origins of the contamination of the marine environment (release of liquid effluents directly into the sea in the vicinity of the damaged reactors, atmospheric fallout onto the surface of the sea, conveyance of radioactive pollution by rainout of contaminated ground). Then, while proposing several maps, the authors analyse and comment the dispersion in the sea of radioactive pollutants by addressing the following issues: topography of the sea bed and sea currents off the Japanese coast, immediate or short term dispersion (a few days), mid-term dispersion (weeks and months), long term and large scale future of the radioactive pollutants. Finally, the report briefly discusses the impact of radioactive pollution on living species

A concept of countermeasure against radioactive wastewater generated in disastrous nuclear accident such as Fukushima Daiichi site case

Energy Technology Data Exchange (ETDEWEB)

Kim, Kwang-Wook; Lee, Keun-Young; Lee, Eil-Hee; Baek, Yeji; So, Ji-Yang; Chung, Dong-Young; Moon, Jei-Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-10-15

Before the operation of initial wastewater treatment systems supplied by AREVA and Kurion companies, which were installed about 6 months after the accident, the contaminated water was accumulated in reactor and turbine buildings, then was moved and stored in many hurriedly-prepared storage tanks including even mega float barge. The wastewater treatment systems using Cs-adsorption columns and desalination equipment was not properly operated and there were several small and big leakages of contaminated water from the wastewater treatment system and storage tanks, so that tremendous wastewater had been accumulated during those periods. That thereafter led to many secondary problems in management and treatment of the wastewater. Since the disastrous accident at Fukushima, several measures to more enhance safety of nuclear power plants located on coastal area have been asked. As one of them, a countermeasure against generation of tremendous radioactive wastewater in disastrous nuclear accident like the Fukushima Daiichi station was asked to be prepared.

Long-term outcomes of patients evacuated from hospitals near the Fukushima Daiichi nuclear power plant after the Great East Japan Earthquake.

Science.gov (United States)

Igarashi, Yutaka; Tagami, Takashi; Hagiwara, Jun; Kanaya, Takahiro; Kido, Norihiro; Omura, Mariko; Tosa, Ryoichi; Yokota, Hiroyuki

2018-01-01

After the accident of the Fukushima Daiichi nuclear power plant due to the Great East Japan Earthquake in March 2011, the Japanese government issued a mandatory evacuation order for people living within a 20 km radius of the nuclear power plant. The aim of the current study was to investigate long-term outcomes of these patients and identify factors related to mortality. Patients who were evacuated from hospitals near the Fukushima Daiichi nuclear power plant to the Aizu Chuo Hospital from 15 to 26 March, 2011 were included in this study. The following data were collected from medical records: age, sex, activities of daily life, hospital they were admitted in at the time of earthquake, distance between the facility and the nuclear power plant, reasons of evacuation and number of transfers. The patient outcomes were collected from medical records and/or investigated on the telephone in January 2012. A total of 97 patients (28 men and 69 women) were transferred from 10 hospitals via ambulances or buses. No patients died or experienced exacerbation during transfer. Median age of the patients was 86 years. Of the total, 36 patients were not able to obey commands, 44 were bed-ridden and 61 were unable to sustain themselves via oral intake of food. Among 86 patients who were followed-up, 41 (48%) died at the end of 2011. Multiple-regression analysis showed that non-oral intake [Hazard Ratio (HR): 6.07, 95% Confidence interval (CI): 1.94-19.0] and male sex [HR: 8.35, 95% CI: 2.14-32.5] had significant impact on mortality. This study found that 48% of the evacuated patients died 9 months after the earthquake and they had significantly higher mortality rate than the nursing home residents. Non-oral intake and male sex had significant impact on mortality. These patients should be considered as especially vulnerable in case of hospital evacuation.

Gene expression analyses of the small intestine of pigs in the ex-evacuation zone of the Fukushima Daiichi Nuclear Power Plant.

Science.gov (United States)

Morimoto, Motoko; Kato, Ayaka; Kobayashi, Jin; Okuda, Kei; Kuwahara, Yoshikazu; Kino, Yasushi; Abe, Yasuyuki; Sekine, Tsutomu; Fukuda, Tomokazu; Isogai, Emiko; Fukumoto, Manabu

2017-11-15

After the accident at the Fukushima Daiichi Nuclear Power Plant, radioactive contaminants were released over a widespread area. Monitoring the biological effects of radiation exposure in animals in the ex-evacuation zone should be continued to understand the health effects of radiation exposure in humans. The present study aimed to clarify the effects of radiation by investigating whether there is any alteration in the morphology and gene expressions of immune molecules in the intestine of pigs and inobuta (wild boar and domestic pig hybrid) in the ex-evacuation zone in 2012. Gene expression analysis was performed in small intestine samples from pigs, which were collected from January to February 2012, in the ex-evacuation zone. Pigs lived freely in this zone, and their small intestine was considered to be affected by the dietary intake of radioactive contaminants. Several genes were selected by microarray analysis for further investigation using real-time polymerase chain reaction. IFN-γ, which is an important inflammatory cytokine, and TLR3, which is a pattern recognize receptor for innate immune system genes, were highly elevated in these pigs. The expressions of the genes of these proteins were associated with the radiation level in the muscles. We also examined the alteration of gene expressions in wild boars 5 years after the disaster. The expression of IFN-γ and TLR3 remained high, and that of Cyclin G1, which is important in the cell cycle, was elevated. We demonstrated that some changes in gene expression occurred in the small intestine of animals in the ex-evacuation zone after radiation. It is difficult to conclude that these alterations are caused by only artificial radionuclides from the Fukushima Daiichi Nuclear Power Plant. However, the animals in the ex-evacuation zone might have experienced some changes owing to radioactive materials, including contaminated soil, small animals, and insects. We need to continue monitoring the effects of long

Spatiotemporal distribution of radioactive cesium released from Fukushima Daiichi Nuclear Power Station in the sediment of Tokyo Bay, Japan

International Nuclear Information System (INIS)

Nakagawa, Ryota; Ishida, Masanobu; Baba, Daisuke; Tanimoto, Satomi; Okamoto, Yuichi; Yamazaki, Hideo

2013-01-01

The spatial and temporal distribution of "1"3"4Cs and "1"3"7Cs released from Fukushima Daiichi Nuclear Power Station in the Tokyo Bay sediments were investigated. The total radioactivity of "1"3"4Cs and "1"3"7Cs detected in the Tokyo Bay sediment ranged from 240 to 870 Bq/kg-dry in the estuary of Arakawa River, but the activities detected in other sites were about 90 Bq/kg-dry or less. These results suggested that radioactive cesium, which precipitated to the ground, was carried to the river along with clay particles by rainfall and transported to the estuary. The vertical distribution of radioactive cesium showed that it invaded deeper than estimated based on the accumulation rate of the sediment. It was described that the vertical distribution of radioactive cesium was affected by physical mixing of sediments by tidal current, flood, and bioturbation of benthos. (author)

Relationship between particle size and radiocesium in fluvial suspended sediment related to the Fukushima Daiichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Kazuya Tanaka

2014-01-01

We collected fluvial suspended sediments in Fukushima after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident and analyzed the 137 Cs concentration in bulk and size-fractioned samples to investigate the particle-size-dependent distribution of radiocesium. The 137 Cs concentration in bulk suspended sediments decreased from August to December 2011, possibly reflecting a decrease of radiocesium concentration in its source materials. Smaller particles had higher radiocesium concentrations, reflecting larger specific surface areas. Silt- and sand-size fractions occupied more than 95 % of the total 137 Cs in the suspended sediments. The contribution of clay-size fractions, which had the highest 137 Cs concentration, was quite small because of their low frequency. A line of the data showed that the particle size distribution of radiocesium was essential to evaluate the migration and distribution of radiocesium in river systems where radiocesium is mainly present as particulate form after the FDNPP accident. (author)

Safety goals for seismic and tsunami risks: Lessons learned from the Fukushima Daiichi disaster

Energy Technology Data Exchange (ETDEWEB)

Saji, Genn, E-mail: sajig@bd5.so-net.ne.jp

2014-12-15

Highlights: • Reviewed why the Fukushima disaster was not anticipated among seismologists. • Reviewed Fukushima Daiichi's preparedness against the earthquake and tsunami. • There was a large “cliff edge” in radiological consequences from the design basis tsunami. • By including earthquakes as an “external event” resulted in insufficient “defense in depths”. • Proposes a new probabilistic seismic and tsunami safety goal be developed. - Abstract: This paper first reviews why the potential occurrence of the Tohoku-oki earthquake with momentum magnitude M{sub w} of 9.0 earthquake was not anticipated by Japanese seismologists, and to clarify our limitations in predicting rare but severe earthquakes at our current knowledge in the field of geosciences. Although there was a large volume of historical records related to earthquakes and tsunamis, generally this data infer high plate coupling in regions where earthquakes were known to have already occurred, with only partial or even no coupling from the Japan Trench to a point approximately midway between the trench and the coastline—precisely the region where the 2011 Tohoku-Oki earthquake occurred. This phenomenon has been explained as a “silent earthquake” or a fault creep as observed at the San Andreas Faults in the US. Considering the large uncertainties in seismic events, nuclear power plants should be conservatively designed with adequate safety margins. TEPCO's preparedness against seismic and tsunami hazards were reviewed in order to clarify why the established safety margin was not sufficient during the Fukushima Daiichi. It was found that the plant incorporated the necessary safety margins against seismic oscillation however, there was a large “cliff edge” in which the radiological consequences surged by several orders of magnitude from the design basis tsunami. Since the tsunami's height was greater than the ground level of the turbine hall, a large amount of the

Safety goals for seismic and tsunami risks: Lessons learned from the Fukushima Daiichi disaster

International Nuclear Information System (INIS)

Saji, Genn

2014-01-01

Highlights: • Reviewed why the Fukushima disaster was not anticipated among seismologists. • Reviewed Fukushima Daiichi's preparedness against the earthquake and tsunami. • There was a large “cliff edge” in radiological consequences from the design basis tsunami. • By including earthquakes as an “external event” resulted in insufficient “defense in depths”. • Proposes a new probabilistic seismic and tsunami safety goal be developed. - Abstract: This paper first reviews why the potential occurrence of the Tohoku-oki earthquake with momentum magnitude M w of 9.0 earthquake was not anticipated by Japanese seismologists, and to clarify our limitations in predicting rare but severe earthquakes at our current knowledge in the field of geosciences. Although there was a large volume of historical records related to earthquakes and tsunamis, generally this data infer high plate coupling in regions where earthquakes were known to have already occurred, with only partial or even no coupling from the Japan Trench to a point approximately midway between the trench and the coastline—precisely the region where the 2011 Tohoku-Oki earthquake occurred. This phenomenon has been explained as a “silent earthquake” or a fault creep as observed at the San Andreas Faults in the US. Considering the large uncertainties in seismic events, nuclear power plants should be conservatively designed with adequate safety margins. TEPCO's preparedness against seismic and tsunami hazards were reviewed in order to clarify why the established safety margin was not sufficient during the Fukushima Daiichi. It was found that the plant incorporated the necessary safety margins against seismic oscillation however, there was a large “cliff edge” in which the radiological consequences surged by several orders of magnitude from the design basis tsunami. Since the tsunami's height was greater than the ground level of the turbine hall, a large amount of the tsunami

Decontamination work in the area surrounding Fukushima Dai-ichi Nuclear Power Plant: another occupational health challenge of the nuclear disaster.

Science.gov (United States)

Wada, Koji; Yoshikawa, Toru; Murata, Masaru

2012-01-01

This article describes occupational health measures for workers involved in decontamination of radioactive material discharged around Fukushima Dai-ichi Nuclear Power Plant after the explosions in 2011. Decontamination is performed by removing radioactive particles (mainly cesium) from surfaces of soil, grass and trees, and buildings. Measurement of radiation doses is necessary to reduce exposure, and to determine whether workers can work below dose limits. Protective equipment for decontamination is determined based on the concentration of radiation in contaminated soil and the exposure to dust. Health examinations by physicians are mandated for decontamination workers upon hiring and every 6 months. While there is no possibility of acute radiation injury from decontamination, workers may be anxious about the unclear effects of chronic low level radiation exposure on health. Measures to protect the decontamination workers are the top priority.

Beef contamination by Cs-134 and Cs-137 in Japan, from the Fukushima Dai-ichi NPP accident

Energy Technology Data Exchange (ETDEWEB)

Kelecom, Alphonse; Cruz, Camila Oliveira da; Paulo Filho, Guilherme de Souza, E-mail: lararapls@hotmail.com, E-mail: camilabiouff@gmail.com, E-mail: akelecom@id.uff.br [Universidade Federal Fluminense (LARARA-PLS/UFF), Niteroi, RJ (Brazil). Lab. de Radiobiologia e Radiometria Pedro Lopes dos Santos; Pereira, Wagner de S., E-mail: pereiraws@gmail.com [Industrias Nucleares do Brasil (UNB), Pocos de Caldas, MG (Brazil). Servico de Radioprotecao. Grupo Multidisciplinar de Radioprotecao

2013-07-01

The most serious earthquake ever registered in Japan occurred on March 11, 2011; it was followed by a tsunami that flowed over the Prefectures of Miyagi and Fukushima destroying roads, cities and rice fields, but also knocking several nuclear power plants. The Dai-ichi plant was seriously damaged and considerable amounts of radioactivity were release contaminating atmosphere, soil, ocean and associated fauna and flora. A major environmental monitoring program started covering the Japanese territory and the sea along the coasts of Miyagi, Fukushima and Ibaraki. Thousands of measurements were released every day by Japanese authorities, the plant operator and Universities principally looking for the presence of I-131, C{sub s}-134 and C{sub s}-137. Drinking water and aliments were seriously contaminated. We here analyze data released during one year on I-131 and C{sub s}-134,137 radioactive concentrations in cattle meat. Along this period I-131, when observed, was present only in trace amounts, but the contamination by cesium isotopes exceeded legal Japanese limit in several Japanese prefectures, and became an acute national and international economic problem. (author)

Probabilistic risk assessment (PRA) update in light of the accident at Fukushima Daiichi Nuclear Power Station - 15461

International Nuclear Information System (INIS)

Maeda, K.; Abe, H.; Hirokawa, N.; Satou, C.

2015-01-01

We have performed internal and external event probabilistic risk assessments (PRA) for boiling water reactor power nuclear plants to identify the important accident sequence groups and to evaluate the effectiveness of the additional severe accident measures, regarding to the new regulatory requirements implemented after the accident at Fukushima Daiichi Nuclear Power Station in Japan in 2011. In addition, we will further update our PRA by extracting problems and improvements from the current PRA, by catching up the state-of-the-art knowledge, modern PRA methodologies in order to contribute voluntarily to safety improvement as well as to comply with regulations. In this document, prior to the extensive PRA updates, we would describe technical contents and qualitative results about PRA updates that have been performed preliminary so far, especially about the external event (seismic) PRA and how to model the additionally deployed severe accident measures (e.g. power supply car, fire engine) so that they can be function external hazards, such as component failure rate of equipment, human reliability 'out of control room', and mission time extension. (authors)

Continuing 137 Cs release to the sea from the Fukushima Dai-ichi Nuclear Power Plant through 2012

Directory of Open Access Journals (Sweden)

J. Kanda

2013-09-01

Full Text Available The rate of cesium-137 (137Cs release to the sea from the Fukushima Dai-ichi Nuclear Power Plant for the period until September 2012 was estimated. Publicly released data on 137Cs radioactivity in seawater near the power plant by Tokyo Electric Power Company strongly suggest a continuing release of radionuclides to the sea. The plant has an artificial harbour facility, and the exchange rate of harbour water with surrounding seawater was estimated by the decrease in radioactivity immediately after an intense radioactive water release. The estimated exchange rate of water in the harbour was 0.44 d−1 during the period from 6 to 19 April. The 137Cs radioactivity in the harbour water was substantially higher than that of seawater outside and remained relatively stable after June 2011. A quasi-steady state was assumed with continuous water exchange, and the average release rate of 137Cs was estimated to be 93 GBq d−1 in summer 2011 and 8.1 GBq d−1 in summer 2012.

Beef contamination by Cs-134 and Cs-137 in Japan, from the Fukushima Dai-ichi NPP accident

International Nuclear Information System (INIS)

Kelecom, Alphonse; Cruz, Camila Oliveira da; Paulo Filho, Guilherme de Souza; Pereira, Wagner de S.

2013-01-01

The most serious earthquake ever registered in Japan occurred on March 11, 2011; it was followed by a tsunami that flowed over the Prefectures of Miyagi and Fukushima destroying roads, cities and rice fields, but also knocking several nuclear power plants. The Dai-ichi plant was seriously damaged and considerable amounts of radioactivity were release contaminating atmosphere, soil, ocean and associated fauna and flora. A major environmental monitoring program started covering the Japanese territory and the sea along the coasts of Miyagi, Fukushima and Ibaraki. Thousands of measurements were released every day by Japanese authorities, the plant operator and Universities principally looking for the presence of I-131, C s -134 and C s -137. Drinking water and aliments were seriously contaminated. We here analyze data released during one year on I-131 and C s -134,137 radioactive concentrations in cattle meat. Along this period I-131, when observed, was present only in trace amounts, but the contamination by cesium isotopes exceeded legal Japanese limit in several Japanese prefectures, and became an acute national and international economic problem. (author)

Internal radiation dose of KURRI volunteers working at evacuation shelters after TEPCO's Fukushima Daiichi nuclear power plant accident

International Nuclear Information System (INIS)

Kurihara, Kouta; Kinashi, Yuko; Okamoto, Kenichi

2013-01-01

We report the radiation doses encountered by 59 Kyoto University Research Reactor Institute (KURRI) staff members who had been dispatched to screen refugees for radiation at emergency evacuation sites 45-80 km from the Tokyo Electric Power Co.'s (TEPCO's) Fukushima Daiichi nuclear power plant. From March 20 to April 30, 2011, 42 members in teams consisting of 2-4 staff members were dispatched 15 times to 7 emergency evacuation sites located 45-80 km from the power plant to examine the radioactive contamination affecting refugees. Continuously, from May 10 to May 23, 2011, 17 members in teams consisting of 2-5 staff members were dispatched 6 times to Fukushima Prefecture to establish the Kyoto University Radiation Mapping (KURAMA) system. Internal burdens of radioactive nuclides were estimated using a whole-body counter consisting of an iron room, NaI (Tl) scintillation detectors, and a digital multichannel analyzer (MCA7600; Seiko EG and G). The calibration of the whole-body counter and the conversion of the measured body burden to the committed effective dose by internal exposure were carried out in accordance with the Nuclear Safety Research Association (NSRA) technical manual. The external radiation dose to each staff member was measured using a personal dosimeter. The first dispatched team showed 1300-1929 Bq of internal radiation activity from cesium (including "1"3"7Cs and "1"3"4Cs) and 48-118 Bq of "1"3"1I. The internal doses of four members of the first team were estimated to be 24-39 μSv. The doses from internal exposure were almost similar to the cumulative external doses for the dispatch period (March 20-22, 2011) when the radiation plumes following the explosions of Units 1 and 3 in TEPCO's Fukushima Daiichi nuclear plant had diffused around Fukushima City. The external radiation doses of members dispatched after the second team had decreased from one-third to less than one-tenth of the external doses of the first dispatched team. The internal

Internal radiation dose of KURRI volunteers working at evacuation shelters after TEPCO's Fukushima Daiichi nuclear power plant accident

International Nuclear Information System (INIS)

Kurihara, Kouta; Kinashi, Yuko; Okamoto, Kenichi

2012-01-01

We report the radiation doses encountered by 59 Kyoto University Research Reactor Institute (KURRI) staff members who had been dispatched to screen refugees for radiation at emergency evacuation sites 45–80 km from the Tokyo Electric Power Co.’s (TEPCO’s) Fukushima Daiichi nuclear power plant. From March 20 to April 30, 2011, 42 members in teams consisting of 2–4 staff members were dispatched 15 times to 7 emergency evacuation sites located 45–80 km from the power plant to examine the radioactive contamination affecting refugees. Continuously, from May 10 to May 23, 2011, 17 members in teams consisting of 2–5 staff members were dispatched 6 times to Fukushima Prefecture to establish the Kyoto University Radiation Mapping (KURAMA) system. Internal burdens of radioactive nuclides were estimated using a whole-body counter consisting of an iron room, NaI (Tl) scintillation detectors, and a digital multichannel analyzer (MCA7600; Seiko EG and G). The calibration of the whole-body counter and the conversion of the measured body burden to the committed effective dose by internal exposure were carried out in accordance with the Nuclear Safety Research Association (NSRA) technical manual. The external radiation dose to each staff member was measured using a personal dosimeter. The first dispatched team showed 1300–1929 Bq of internal radiation activity from cesium (including "1"3"7Cs and "1"3"4Cs) and 48–118 Bq of "1"3"1I. The internal doses of four members of the first team were estimated to be 24–39 μSv. The doses from internal exposure were almost similar to the cumulative external doses for the dispatch period (March 20–22, 2011) when the radiation plumes following the explosions of Units 1 and 3 in TEPCO’s Fukushima Daiichi nuclear plant had diffused around Fukushima City. The external radiation doses of members dispatched after the second team had decreased from one-third to less than one-tenth of the external doses of the first dispatched team

Simultaneous sampling of indoor and outdoor airborne radioactivity after the Fukushima Daiichi nuclear power plant accident.

Science.gov (United States)

Ishikawa, Tetsuo; Sorimachi, Atsuyuki; Arae, Hideki; Sahoo, Sarata Kumar; Janik, Miroslaw; Hosoda, Masahiro; Tokonami, Shinji

2014-02-18

Several studies have estimated inhalation doses for the public because of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. Most of them were based on measurement of radioactivity in outdoor air and included the assumption that people stayed outdoors all day. Although this assumption gives a conservative estimate, it is not realistic. The "air decontamination factor" (ratio of indoor to outdoor air radionuclide concentrations) was estimated from simultaneous sampling of radioactivity in both inside and outside air of one building. The building was a workplace and located at the National Institute of Radiological Sciences (NIRS) in Chiba Prefecture, Japan. Aerosol-associated radioactive materials in air were collected onto filters, and the filters were analyzed by γ spectrometry at NIRS. The filter sampling was started on March 15, 2011 and was continued for more than 1 year. Several radionuclides, such as (131)I, (134)Cs, and (137)Cs were found by measuring the filters with a germanium detector. The air decontamination factor was around 0.64 for particulate (131)I and 0.58 for (137)Cs. These values could give implications for the ratio of indoor to outdoor radionuclide concentrations after the FDNPP accident for a similar type of building.

Comparison of direct deposition and root uptake results after the Fukushima Daiichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Tagami, Keiko; Uchida, Shigeo

2012-01-01

Field horsetail(Equisetum arvense) is a kind of fern, and the fertile shoots are eaten as vegetables in Japan in the spring. Since fern species tend to concentrate radiocaesium from soil, concentrations and distribution patterns of radiocaesium in the fertile shoots are of interest. In this study, distribution and food processing results were compared using samples collected in 2011(n=1) and 2012(n=3); the sample collected in 2011 received direct deposition from the Fukushima Daiichi Nuclear Power Plant accident while those collected in 2012 included radiocaesium mainly taken up from soil. About 200-300 shoots were collected at each sampling time. The 137 Cs concentration in samples collected in 2012 decreased by 100-200 times compared to that in 2011. The radiocaesium distribution patterns in strobili, leaves and stems of 2012 samples were almost the same as those of 2011; however, the patterns were different from those of potassium. The radiocaesium removal percentage by food processing (washing + boiling for 2.5min) was 70% in 2011, while that for 2012 samples was 32-72%; the effect of direct deposition and root uptake was not clear. (author)

Birth Outcomes after the Fukushima Daiichi Nuclear Power Plant Disaster: A Long-Term Retrospective Study

Science.gov (United States)

Leppold, Claire; Nomura, Shuhei; Sawano, Toyoaki; Ozaki, Akihiko; Tsubokura, Masaharu; Hill, Sarah; Kanazawa, Yukio; Anbe, Hiroshi

2017-01-01

Changes in population birth outcomes, including increases in low birthweight or preterm births, have been documented after natural and manmade disasters. However, information is limited following the 2011 Fukushima Daiichi Nuclear Power Plant Disaster. In this study, we assessed whether there were long-term changes in birth outcomes post-disaster, compared to pre-disaster data, and whether residential area and food purchasing patterns, as proxy measurements of evacuation and radiation-related anxiety, were associated with post-disaster birth outcomes. Maternal and perinatal data were retrospectively collected for all live singleton births at a public hospital, located 23 km from the power plant, from 2008 to 2015. Proportions of low birthweight (increased proportions of low birthweight or preterm births in any year after the disaster (merged post-disaster risk ratio of low birthweight birth: 0.98, 95% confidence interval (CI): 0.64–1.51; and preterm birth: 0.68, 95% CI: 0.38–1.21). No significant associations between birth outcomes and residential area or food purchasing patterns were identified, after adjustment for covariates. In conclusion, no changes in birth outcomes were found in this institution-based investigation after the Fukushima disaster. Further research is needed on the pathways that may exacerbate or reduce disaster effects on maternal and perinatal health. PMID:28534840

Variation of radiocesium concentrations in cedar pollen in the Okutama area since the Fukushima Daiichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Tsuruoka, H.; Inoue, K.; Sakano, Y.; Hamada, M.; Shimizu, H.; Fukushi, M.

2015-01-01

Due to releases of radionuclides in the Fukushima Daiichi Nuclear Power Plant accident, radiocesium ( 134 Cs and 137 Cs) has been incorporated into large varieties of plant species and soil types. There is a possibility that radiocesium taken into plants is being diffused by pollen. Radiocesium concentrations in cedar pollen have been measured in Ome City, located in the Okutama area of metropolitan Tokyo, for the past 3 y. In this research, the variation of radiocesium concentrations was analysed by comparing data from 2011 to 2014. Air dose rates at 1 m above the ground surface in Ome City from 2011 to 2014 showed no significant difference. Concentration of 137 Cs contained in the cedar pollen in 2012 was about half that in 2011. Between 2012 and 2014, the concentration decreased by approximately one-fifth, which was similar to the result of a press release distributed by the Japanese Ministry of Agriculture, Forestry and Fisheries. (authors)

CANDU heat sinks improvements as a follow up to Fukushima Daiichi accident ''the regulator perspective''

Energy Technology Data Exchange (ETDEWEB)

Mesmous, Noreddine; Harwood, Chris [Canadian Nuclear Safety Commission, Ottawa, ON (Canada)

2015-06-15

The purpose of this paper is to provide a summary of the Canadian Nuclear Safety Commission (CNSC) recommendations related to improving the heat sink strategy as a follow up to the Fukushima Daiichi Accident (FDA). As a follow up to FDA, CNSC staff tasked the Nuclear Power Plant (NPP) licensees to review the lessons learned from the FDA and re-examine the NPP safety cases. The reviews have examined the CANDU defence-in-depth strategy and considered events more severe than those that have historically been regarded as credible, and evaluated their impact on the NPPs safety. Availability of emergency equipment was shown to be crucial during the FDA and its availability could have arrested the accident progression early enough to minimize any radioactive release to the environment. As a result, licensees presented appropriate evaluations of the means to provide coolant make-up to the primary Heat Transport System (HTS), boilers, moderator, calandria vault, and irradiated fuel pools.

Fusion of aerial gamma-ray survey and remote sensing data for a deeper understanding of radionuclide fate after radiological incidents. Examples from the Fukushima Dai-Ichi response

International Nuclear Information System (INIS)

Czaja, Wojciech; Manning, Benjamin; Murphy, J.M.

2016-01-01

We consider fusion of heterogeneous data, consisting of multispectral imagery collected from the WorldView-2 satellite and aerial gamma-ray spectra collected during the NNSA Aerial Measuring System response to the Fukushima Dai-ichi Nuclear Power Plant crisis. These data are analyzed using the non-linear dimension reduction technique of diffusion maps. The data is then used for classification of regions in the scene. A strong spatial coherence is observed in the gamma-ray data that is closely coupled to the underlying terrain classification obtained from the multispectral data, indicating correlation between these a priori uncorrelated measurements. (author)

An assessment of radiation doses at an educational institution 57.8 km away from the Fukushima Daiichi nuclear power plant 1 month after the nuclear accident.

Science.gov (United States)

Tsuji, Masayoshi; Kanda, Hideyuki; Kakamu, Takeyasu; Kobayashi, Daisuke; Miyake, Masao; Hayakawa, Takehito; Mori, Yayoi; Okochi, Toshiyasu; Hazama, Akihiro; Fukushima, Tetsuhito

2012-03-01

On 11 March 2011, the Great East Japan Earthquake occurred. Due to this earthquake and subsequent tsunami, malfunctions occurred at the Fukushima Daiichi nuclear power plant. Radioactive material even reached the investigated educational institution despite being 57.8 km away from the power station. With the goal of ensuring the safety of our students, we decided to carry out a risk assessment of the premises of this educational institution by measuring radiation doses at certain locations, making it possible to calculate estimated radiation accumulation. Systematic sampling was carried out at measurement points spaced at regular intervals for a total of 24 indoor and outdoor areas, with 137 measurements at heights of 1 cm and 100 cm above the ground surface. Radiation survey meters were used to measure environmental radiation doses. Radiation dose rates and count rates were higher outdoors than indoors, and higher 1 cm above the ground surface than at 100 cm. Radiation doses 1 cm above the ground surface were higher on grass and moss than on asphalt and soil. The estimated radiation exposure for a student spending an average of 11 h on site at this educational institution was 9.80 μSv. Environmental radiation doses at our educational institution 57.8 km away from the Fukushima Daiichi nuclear power plant 1 month after the accident were lower than the national regulation dose for schools (3.8 μSv/h) at most points. Differences in radiation doses depending on outdoor surface properties are important to note for risk reduction.

Atmospheric behavior, deposition, and budget of radioactive materials from the Fukushima Daiichi nuclear power plant in March 2011

Science.gov (United States)

Morino, Y.; Ohara, T.; Nishizawa, M.

2011-12-01

To understand the atmospheric behavior of radioactive materials emitted from the Fukushima Daiichi nuclear power plant after the nuclear accident that accompanied the great Tohoku earthquake and tsunami on 11 March 2011, we simulated the transport and deposition of iodine-131 and cesium-137 using a chemical transport model. The model roughly reproduced the observed temporal and spatial variations of deposition rates over 15 Japanese prefectures (60-400 km from the plant), including Tokyo, although there were some discrepancies between the simulated and observed rates. These discrepancies were likely due to uncertainties in the simulation of emission, transport, and deposition processes in the model. A budget analysis indicated that approximately 13% of iodine-131 and 22% of cesium-137 were deposited over land in Japan, and the rest was deposited over the ocean or transported out of the model domain (700 × 700 km2). Radioactivity budgets are sensitive to temporal emission patterns. Accurate estimation of emissions to the air is important for estimation of the atmospheric behavior of radionuclides and their subsequent behavior in land water, soil, vegetation, and the ocean.

Continuing {sup 137}Cs release to the sea from the Fukushima Dai-ichi nuclear power plant through 2012

Energy Technology Data Exchange (ETDEWEB)

Kanda, J. [Tokyo Univ. of Marine Science and Technology (Japan). Dept. of Ocean Sciences

2013-07-01

The rate of cesium-137 ({sup 137}Cs) release to the sea from the Fukushima Dai-ichi Nuclear Power Plant for the period until September 2012 was estimated. Publicly released data on {sup 137}Cs radioactivity in seawater near the power plant by Tokyo Electric Power Company strongly suggest a continuing release of radionuclides to the sea. The plant has an artificial harbour facility, and the exchange rate of harbour water with surrounding seawater was estimated by the decrease in radioactivity immediately after an intense radioactive water release. The estimated exchange rate of water in the harbour was 0.44 d{sup -1} during the period from 6 to 19 April. The {sup 137}Cs radioactivity in the harbour water was substantially higher than that of seawater outside and remained relatively stable after June 2011. A quasi-steady state was assumed with continuous water exchange, and the average release rate of {sup 137}Cs was estimated to be 93 GBq d{sup -1} in summer 2011 and 8.1 GBq d{sup -1} in summer 2012.

Post-processing activities after Chernobyl accident in Ukraine and lesson learned to the response Fukushima Dai-ichi accident

International Nuclear Information System (INIS)

Fujii, Yuzo

2012-01-01

After the accident of Chernobyl NPP no.4 1986, various activities including the construction of the shelter, prevention of the release of radioactive dust and liquid from the shelter, monitoring the condition of the damaged core, and disposal of radioactive waste have been implemented in the Chernobyl site for mitigating the nuclear and radioactive risks of damaged nuclear facilities, and the reducing radiation dose of working personnel. The construction of new shelter started for the decommissioning of the damaged unit no.4. facility. For reducing the radiation dose to the inhabitants from the contaminated land and feedstuff, the countermeasures including the set of the exclusive zone and permissible level of radionuclide in the foodstuff have been conducted for the countrywide. These activities include many valuable information about how to recover the condition of the site and maintain the social activities after the severe accident of NPP, and it would be important to learn the above activities in conducting the post-processing activities on the Fukushima-Daiichi accident successfully. (author)

Tritium in Japanese precipitation following the March 2011 Fukushima Daiichi Nuclear Plant accident

Energy Technology Data Exchange (ETDEWEB)

Matsumoto, Takuya, E-mail: t.matsumoto@iaea.org [Isotope Hydrology Section, Division of Physical and Chemical Sciences, International Atomic Energy Agency, Vienna International Centre, 1400 Vienna (Austria); Maruoka, Teruyuki [Division of Integrative Environmental Sciences Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba City, Ibaraki 305-8572 (Japan); Shimoda, Gen [Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba City, Ibaraki 305-8561 (Japan); Obata, Hajime [Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa-shi, Chiba 277-8564 (Japan); Kagi, Hiroyuki [Geochemical Research Center, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Suzuki, Katsuhiko [Japan Agency for Marin-Earth Science and Technology, 2-15, Natsushima, Yokosuka, Kanagawa 237-0061 (Japan); Yamamoto, Koshi [Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan); Mitsuguchi, Takehiro [215 Ooma Akadoji-cho Konan, 483-8226 (Japan); Usa Marine Biological Institute, Kochi University, 194 Inoshiri, Usa, Tosa, Kochi 781-1164 (Japan); Hagino, Kyoko; Tomioka, Naotaka [Institute for Study of the Earth' s Interior, Okayama University at Misasa, 827 Yamada, Misasa, Tottori 682-0193 (Japan); Sambandam, Chinmaya; Brummer, Daniela; Klaus, Philipp Martin; Aggarwal, Pradeep [Isotope Hydrology Section, Division of Physical and Chemical Sciences, International Atomic Energy Agency, Vienna International Centre, 1400 Vienna (Austria)

2013-02-15

Tritium concentrations in Japanese precipitation samples collected after the March 2011 accident at the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) were measured. Values exceeding the pre-accident background were detected at three out of seven localities (Tsukuba, Kashiwa and Hongo) southwest of the FNPP1 at distances varying between 170 and 220 km from the source. The highest tritium content was found in the first rainfall in Tsukuba after the accident; however concentrations were 500 times less than the regulatory limit for tritium in drinking water. Tritium concentrations decreased steadily and rapidly with time, becoming indistinguishable from the pre-accident values within five weeks. The atmospheric tritium activities in the vicinity of the FNPP1 during the earliest stage of the accident was estimated to be 1.5 × 10{sup 3} Bq/m{sup 3}, which is potentially capable of producing rainwater exceeding the regulatory limit, but only in the immediate vicinity of the source. - Highlights: ► We measured the {sup 3}H contents of Japanese rain collected after the Fukushima accident. ► {sup 3}H level became 30 times higher than pre-accident level in the first rain at Tsukuba. ► Some locality within 220 km from the source showed elevated {sup 3}H levels. ► These high {sup 3}H signals disappear in a few weeks. ► Atmospheric {sup 3}H level at the source during the earliest stage was estimated to be 1500 Bq/m{sup 3}.

Suppositional analysis for the nuclear accidents at the Fukushima Daiichi Nuclear Power Station

International Nuclear Information System (INIS)

Yoshida, Yoshitaka

2012-01-01

The Great East Japan Earthquake which occurred on March 11, 2011 set off a series of events that have led to a serious nuclear disaster. The Fukushima Daiichi Nuclear Power Station suffered damage due to the huge tsunami waves triggered by the earthquake, which lead to release of large amounts of radioactive materials into the environment. Using the limited information presented by the government and others within several days after the accident, this study examined the amount of radioactive materials released into the atmosphere predicted using the incident progress prediction system (IPPS) and the radioactive release, radiation dose and radiological protection area prediction system (R-Cubic) each developed by INSS, and compared those findings with the amount of radioactive materials evaluated by the government and the Tokyo Electric Power Company. The following points were seen (1) The step-by-step public protection measures taken by the government were consistent with the amount of released radioactive materials by R-Cubic. (2) The IPPS underestimated the amount of released radioactive materials when the irradiation levels in the nuclear reactors were analyzed according to the observed nuclear reactor water levels, although these were well in agreement with the observed parameters. (3) The amounts of released radioactive materials predicted by R-Cubic agreed well with those of the Nuclear Safety Commission and the Nuclear and Industrial Safety Agency. (4) The 0.5MeV equivalent value of noble gases in the amount of radioactive materials released into the atmosphere shown by TEPCO on May 2012 was considered to be an underestimate. (author)

The Recent Situation of Fukushima Daiichi Plants and the Related Water Chemistry Problems

International Nuclear Information System (INIS)

Makihira, Atsutoshi; GOTO, Akira; Ishikawa, Keiji

2012-09-01

Fukushima Daiichi Nuclear Power Station was hit by the big earthquake and tsunami, which caused the station black out and subsequent loss of cooling functions for reactors and spent fuel pools (SFPs). Consequently the fuels were damaged, hydrogen explosion blew off top of the reactor buildings and radioactive materials were released to the atmosphere and the ocean. In the accident, one of the most important mission is to cool the reactors and SFPs stably with removing radionuclides and impurities in the water. The water injected into the reactors has been leaked off and accumulated in the basement of the reactor and turbine buildings. Hence the water was highly contaminated, we had to purify it and reused for cooling by 'circulating water cooling system'. The system is mainly composed of removal of radioactive materials and desalination. With improving the equipment reliability, sufficient quantity of cooling water is being able to supply for the reactors. We have achieved the inside reactor temperatures of units 1,2,3 approximately below 100 degrees C as of December 2011. The SFPs were firstly cooled by spraying water from the outside at rooftop areas, or seawater was injected through a piping of Fuel Pool Cooling System (FPC). Afterwards, alternative circulating cooling systems were installed that allowed SFPs of unit 1 to 4 for cooling. The water purification system was also introduced for preventing corrosion of SFP lining. By using the system, SFP water quality has been improved and each temperature is stable at approximately 30 degree C as of June 2012. (authors)

Estimation of in-plant source term release behaviors from Fukushima daiichi reactor cores by forward method and comparison with reverse method

Energy Technology Data Exchange (ETDEWEB)

Kim, Tae Won; Rhee, Bo Wook; Song, Jin Ho; Kim, Sung Il; Ha, Kwang Soon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2017-06-15

The purpose of this paper is to confirm the event timings and the magnitude of fission product aerosol release from the Fukushima accident. Over a few hundreds of technical papers have been published on the environmental impact of Fukushima Daiichi accident since the accident occurred on March 11, 2011. However, most of the research used reverse or inverse method based on the monitoring of activities in the remote places and only few papers attempted to estimate the release of fission products from individual reactor core or from individual spent fuel pool. Severe accident analysis code can be used to estimate the radioactive release from which reactor core and from which radionuclide the peaks in monitoring points can be generated. The basic material used for this study are the initial core inventory obtained from the report JAEA-Data/Code 2012–018 and the given accident scenarios provided by Japanese Government or Tokyo Electric Power Company (TEPCO) in official reports. In this research a forward method using severe accident progression code is used as it might be useful for justifying the results of reverse or inverse method or vice versa. The release timing and amounts to the environment are estimated for volatile radioactive fission products such as noble gases, cesium, iodine, and tellurium up to 184 hours (about 7.7 days) after earthquake occurs. The in-plant fission product behaviors and release characteristics to environment are estimated using the severe accident progression analysis code, MELCOR, for Fukushima Daiichi accident. These results are compared with other research results which are summarized in UNSCEAR 2013 Report and other technical papers. Also it may provide the physically based arguments for justifying or suspecting the rationale for the scenarios provided in open literature. The estimated results by MELCOR code simulation of this study indicate that the release amount of volatile fission products to environment from Units 1, 2, and 3

Time series changes in radiocaesium distribution in tea plants (Camellia sinensis (L.)) after the Fukushima Dai-ichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Hirono, Yuhei; Nonaka, Kunihiko

2016-01-01

Radiocaesium ( 134 Cs and 137 Cs) release following the accident at the Fukushima Dai-ichi Nuclear Power Plant, belonging to the Tokyo Electric Power Company caused severe contamination of new tea plant (Camellia sinensis (L.)) shoots by radiocaesium in many prefectures in eastern Japan. Because tea plants are perennial crops, there is the fear that the contamination might last for a long time. The objectives of this study were to reveal time series changes in the distribution of radiocaesium in tea plants after radioactive fallout and to evaluate the effect of pruning on reduction of radiocaesium concentrations in new shoots growing next year. The experimental tea field was located in Shizuoka, Japan, approximately 400 km away from the Fukushima Dai-ichi Nuclear Power Plant in a southwest direction. Time series changes in radiocaesium concentrations in unrefined tea, a tea product primarily produced for making Japanese green tea, from May 2011 to June 2013 and distribution of radiocaesium in tea plants from May 2011 to May 2012 were monitored. The radiocaesium concentrations in unrefined tea exponentially decreased; the effective half-lives for 134 Cs and 137 Cs were 0.30 and 0.36 y during the first 2 y after the accident, respectively. With time, the highest concentrations of 137 Cs moved from the upper to the lower parts of plants. Medium pruning 2–3 months after the accident reduced the concentration of 137 Cs in new shoots harvested in the first crop season of the following year by 56% compared with unpruned tea plants; thus, pruning is an effective measure for reducing radiocaesium concentration in tea. - Highlights: • Effective half-life of 137 Cs for first 2 y in new shoots of tea plants is 0.36 y. • Effective half-life of 134 Cs for first 2 y in new shoots of tea plants is 0.30 y. • 81% of radiocaesium existed in foliar layer and branches in 3 months after fallout. • High radiocaesium activity moved from upper to lower parts of tea plants

Development of radioactive wastewater treatment systems at Fukushima Daiichi Nuclear Power Station and Toshiba's efforts

International Nuclear Information System (INIS)

Arima, Yuki; Takeuchi, Tsutomu; Yoshino, Akira

2012-01-01

In keeping the condition of the Fukushima Daiichi Nuclear Power Station (NPS) of The Tokyo Electric Power Company, Inc. under control, following the serious damage to the NPS as a result of the Great East Japan Earthquake and subsequent tsunami on March 11, 2011, both stable cooling of the reactors and spent fuel pools and control of the radioactive wastewater to prevent release have been crucial issues. The reactor cooling has depended on the injection of water from outside, with seawater used first for approximately one month, after which the supply was changed to filtered water. In both cases, however, the water flowed into the reactor buildings and turbine buildings. Toshiba contributed to the realization of circulating water injection cooling at the NPS by supplying a radioactive wastewater transferral system and the first purification system in the initial three months, followed by a second purification system, called SARRY TM , which provided stable treatment capability. These systems make it possible to reuse injected water by purification for further injection, eliminating the need for additional water from the outside. These systems also decrease wastewater generation in the NPS and minimize the risk of spills into the environment. (author)

Enhancement of organizational resilience in light of the Fukushima Dai-ichi Nuclear Power Plant accident (2). Promoting of attitude-building measures

International Nuclear Information System (INIS)

Oba, Kyoko; Yoshizawa, Atsufumi; Kitamura, Masaharu

2014-01-01

The disaster of Fukushima-Daiichi Nuclear Power Plant was indeed an unprecedented accident. However, the consequence could have been worse without tremendous struggles of the personnel on the site. In order to identify the key factors that enabled such tremendous and self-sacrificing struggles, documents including narrative statements of the personnel have been reviewed. The ultimate purpose of this paper is to enhance operational resilience of nuclear power plants. Out of the four key capabilities proposed in the framework of resilience engineering, the capability to respond has been mainly studied. Particular attention has been paid to attitude of operators which definitely contributed to the outstanding behaviors. Through extensive reviewing activities, number of factors such as the sense of vocation, consciousness for one's own plants, sprit of operator, leadership, followership, comradeship, regional loyalty, connection with family, etc. have been identified as the important driving forces that contributed to the honorable attitude. (author)

Radioactive caesium contamination due to Fukushima Daiichi Nuclear Power Plants accident in Osaka city. Evaluation of accumulation and decontamination of radioactive materials via reverse logistics function of a city

International Nuclear Information System (INIS)

Nishio, Takayuki; Kitano, Masaaki; Sakai, Mamoru; Takakura, Akito; Katahira, Kenshi; Nishitani, Takashi

2015-01-01

We surveyed background level of radioactive contamination in city area of Osaka before combusting the wide area disposal of disastrous debris at a municipal waste incineration plant of Osaka city. The debris was caused by Tohoku district great earthquake disaster and suspected to be contaminated with radionuclides released from the Fukushima Daiichi Nuclear Power Plants. We also investigated radioactivity in incineration ash of municipal waste incineration plants and of sewage treatment plants, as well as in water clarifier sludge of potable water treatment plants, and evaluated the accumulation and cleansing of radioactive materials via the reverse logistic function of the city. Radioactive caesium deposited in Osaka city area was estimated to be approximately 4.3 GBq from the concentrations observed in the monthly fallout, whereas that collected as municipal wastes and sewage was estimated to be approximately 0.9 GBq a year in 2011. Even two years after the accident, "1"3"4Cs, which is the evidence of the Fukushima Daiichi Nuclear Power Plant accident, had been detected in the municipal wastes at a level comparable to the activities found just after the accident, however, the radioactive caesium concentration in fallout measured in the Osaka city area had decreased below a detection limit after May 2012. Introduction of materials contaminated with radioactive caesium from outside the city area was suspected because the observed contamination level was inexplicable by that of observed in the environmental wastes such as pruned branches which are contaminated by with the fallout in city area of Osaka. (author)

Accident of the Fukushima-Daiichi nuclear power station. Situation two years after the event - IRSN file

International Nuclear Information System (INIS)

2013-03-01

Two years after the Fukushima accident, this report proposes a review of the situation in Japan, and of the European and international actions aimed at preventing the occurrence of another nuclear accident and its radiological consequences. It is based on information available at the end of January or February 2013. After a recall of the situation in Japan and Europe in 2011 (recall of the accident, of the different simulation, calculation and information actions undertaken by the IRSN, launching of a program of additional safety assessments and of European stress tests), the report addresses the situation in Japan two years after the accident: evolution of the nuclear risk management governance, status of the Fukushima-Daiichi power station, health and environmental impact and management of the post-accidental phase, actions undertaken by the IRSN (dose assessment, cooperation in the field of severe accidents, participation to the Fukushima Dialogue). The next part details the contribution of the IRSN to the strengthening of safety and radiation protection at the international level (in relationship with international organizations: IAEA, UNSCEAR and WHO). Additional technical information is provided in appendix, as well as a report on the environmental impact of the accident, and a report on the post-accidental management of the accident

Report of “the 2013 international forum on peaceful use of nuclear energy, nuclear non-proliferation and nuclear security. Ensuring nuclear non-proliferation and nuclear security of nuclear fuel cycle options in consideration of the accident at TEPCO's Fukushima Daiichi Nuclear Power Station”

International Nuclear Information System (INIS)

Yamamura, Tsukasa; Suda, Kazunori; Tomikawa, Hirofumi; Suzuki, Mitsutoshi; Kuno, Yusuke; Mochiji, Toshiro

2014-03-01

The Japan Atomic Energy Agency (JAEA) held “International Forum on Peaceful Use of Nuclear Energy, Nuclear Non-proliferation and Nuclear Security – Ensuring Nuclear Non-Proliferation and Nuclear Security of Nuclear Fuel Cycle Options in consideration of the Accident at TEPCO's Fukushima Daiichi Nuclear Power Station –” on 3 and 4 December 2013, with the Japan Institute of International Affairs (JIIA) and School of Engineering, The University of Tokyo, as co-hosts. In the Forum, officials from Japan, the United States, France and International Atomic Energy Agency (IAEA) explained their efforts regarding peaceful use of nuclear energy and nuclear non-proliferation. Discussion was made in two panels, entitled “Nuclear non-proliferation and nuclear security measures of nuclear fuel cycle options in consideration of the Accident at TEPCO's Fukushima Daiichi Nuclear Power Station” and “Roles of safeguards and technical measures for ensuring nuclear non-proliferation for nuclear fuel cycle options”. In the first panel based on the implications of the Accident at TEPCO's Fukushima Daiichi Nuclear Power Station on the domestic and global nuclear energy use and increased interest in the back end of nuclear fuel cycle, discussion was made on nuclear non-proliferation and nuclear security challenges on both fuel cycle options from the policy and institutional viewpoints whereas in the second panel the roles of safeguards and proliferation resistant nuclear technology including plutonium burning technology in ensuring nuclear non-proliferation and nuclear security in the back end of nuclear fuel cycle were discussed. Officials and experts from Japan, IAEA, the United States, France and Republic of Korea participated in the panel and made contributions to active discussion. This report includes abstracts of keynote speeches, summaries of two panel discussions and materials of the presentations in the forum. The editors take full responsibility for the wording

Radiocesium concentrations in wild mushrooms collected in Kawauchi Village after the accident at the Fukushima Daiichi Nuclear Power Plant

Directory of Open Access Journals (Sweden)

Kanami Nakashima

2015-11-01

Full Text Available It is well known from the experience after the 1986 accident at the Chernobyl Nuclear Power Plant that radiocesium tends to concentrate in wild mushrooms. In this study, we collected wild mushrooms from the Kawauchi Village of Fukushima Prefecture, located within 30 km of the Fukushima Daiichi Nuclear Power Plant, and evaluated their radiocesium concentrations to estimate the risk of internal radiation exposure in local residents. We found that radioactive cesium exceeding 100 Bq/kg was detected in 125 of 154 mushrooms (81.2%. We calculated committed effective doses based on 6,278 g per year (age > 20 years, 17.2 g/day, the average intake of Japanese citizens, ranging from doses of 0.11–1.60 mSv, respectively. Although committed effective doses are limited even if residents eat contaminated foods several times, we believe that comprehensive risk-communication based on the results of the radiocesium measurements of food, water, and soil is necessary for the recovery of Fukushima after this nuclear disaster.

Pu distribution in seawater in the near coastal area off Fukushima after the Fukushima Daiichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Bu, W.T.; Zheng, J.; Aono, T.; Wu, J.W.; Tagami, K.; Uchida, S.; Guo, Q.J.; Yamada, M.

2015-01-01

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released large amount of radionuclides into the marine environment. Compared with the fission products, data on the distributions of Pu in the marine environment of the western North Pacific after the accident is limited. To better understand the Pu contamination in the marine environment after the accident, for the first time, we determined Pu isotope ratio ( 240 Pu/ 239 Pu) in addition to 239+240 Pu activity in seawater collected in the near coastal area (mostly within the 30 km zone) off the FDNPP site. The 239+240P u activities were 4.16-5.52 mBq/m 3 and the 240 Pu/ 239 Pu atom ratios varied from 0.221 to 0.295. These values were compared with the baseline data for Pu distribution in the near coast seawaters before the FDNPP accident (2008-2010). The results suggested that there is no significant Pu contamination in seawater in the near coastal area off the FDNPP site from the accident two years after the accident. (author)

iB1350 no.1. A generation III.7 reactor after the Fukushima Daiichi accident

International Nuclear Information System (INIS)

Sato, Takashi; Matsumoto, Keiji; Hosomi, Kenji; Kojima, Yoshihiro; Taguchi, Keisuke

2017-01-01

iB1350 stands for an innovative, intelligent and inexpensive BWR 1350. It is the first generation III.7 reactor after the Fukushima Daiichi accident. It has incorporated lessons learned from the Fukushima Daiichi accident and WENRA safety objectives. It has innovative safety to cope with devastating natural disasters including a giant earthquake, a large tsunami and a monster hurricane. The iB1350 can survive passively such devastation and a very prolonged SBO without any support from the outside of a site up to 7 days even preventing core melt. It, however, is based on the well-established proven ABWR design. The NSSS is exactly the same as that of the current ABWR. As for safety design, it has a double cylinder RCCV (Mark W containment) and in-depth hybrid safety systems (IDHS). The Mark W containment has double FP confinement barriers and the in-containment filtered venting system (IFVS) that enable passively no emergency evacuation outside the immediate vicinity of the plant for a SA. It has a large volume to hold hydrogen, an innovative core catcher (iCC), a passive flooding system and an innovative passive containment cooling system (iPCCS) establishing passively practical elimination of containment failure even in a long term. The IDHS consists of 4 division active safety systems for a DBA, 2 division active safety systems for a SA and built-in passive safety systems (BiPSS) consisting of an isolation condenser (IC) and the iPCCS for a SA. While the conventional PCCS can never cool the S/P, the iPCCS can automatically cool the S/P directly even in a DBA LOCA. That makes it possible for the iB1350 to optimize the active safety systems for a DBA. Sato came up with several optimized configurations of the IDHS that are expected to achieve further cost reduction and enhance its reliability resulting from passive feature of the iPCCS. The IC/iPCCS pool has enough capacity for 7 day grace period. The IC/iPCCS heat exchangers, the core and the spent fuel pool are

Recent condition of Fukushima-Daiichi nuclear plant accident in Japan

Science.gov (United States)

Ohnishi, Takeo

2012-07-01

Japanese government pronounced that the second step had been succeeded in the cooling down of the reactors on the middle of Dec 2011 at Fukushima-Daiichi nuclear power plant. In future, government aims to take out fuels from 4 reactors and shields their units. The nuclear power plants in Japan are gradually decreasing, because the checking for them has been performed and the permission of the re-start of them are difficult to be gained. On January 1st 2012, only 7 units are operating in Japan, though the about 54 units were set before the accident. At the end of December 2011, most radiations are emitted from cesium. The radioactivity in air and land around the plant was daily reported in newspaper. Government often gave the information about some RI-contamination in foods. They were taken off from the markets. At now stage, the most important project is the decontamination of radioactive materials from houses, schools, public facilities and industries. Government will newly classify three evacuation areas from April 2012. At the end of March, evacuees under 20 mSv/year possibly can go back their homes (evacuation-free area). The environmental doses will be depressed by decontamination under 10 mSv/year. At the range of 20-50 mSv, people will be controlled to live these area, they can go back their houses temporally (evacuation area). Over 50 mSv/year, however, people can go back house until 5 years at least (prohibited area). In new radiation limitation for a risk of human health, government made 100 mSv and 20 mSv for life span for one year, respectively. The aim of decontamination was set up to 10 mSv for 1 year and 5 mSv for next stage. A target at school is under1 mSv for children. Government accepted a new severe limitation per1 Kg at four groups; milk of baby (100 Bq) and milk (100 Bq), drinking water (10 Bq) and food (100 Bq). Tokyo electric Power Company and government should pay the sufficient compensation to evacuees. In future, they should keep health

Synthesis of the available information about the radioactive contamination of the Japanese terrestrial environment caused by the Fukushima Dai-ichi accident - May 25, 2011

International Nuclear Information System (INIS)

2011-01-01

The French institute of radiation protection and nuclear safety (IRSN) collects and analyses regularly the published data concerning the contamination of the Japanese terrestrial environment caused by the Fukushima Dai-ichi power plant accident. This synthesis presents a status of the data recently obtained since the previous similar note of April 12. The note presents a mapping of 137 Cs and 134 Cs cumulated deposits in a 80 km area around the damaged power plant, an estimation of the cumulated atmospheric precipitations during March 15-16 night, the evolution of the gamma dose rates in the ambient air of several towns of the Fukushima district, the evolution of the 134 Cs+ 137 Cs and 131 I contamination of agriculture food products and of surface and drinking waters. (J.S.)

The groundwater problems and countermeasures of Fukushima Daiichi Nuclear Power Plant in 2014. In order to take off the protective clothing

International Nuclear Information System (INIS)

Marui, Atsunao

2014-01-01

Since the accident of Fukushima Daiichi Nuclear Power Station in March 2011, groundwater problem and its countermeasures have been reported in a variety of ways. Its information is hardly intended to accurately convey the purpose or circumstances, which generated a lot of misunderstanding. This paper rechecked the on-site geology and groundwater conditions. Based on the long-term plans of the government and Tokyo Electric Power Company toward the decommissioning, it mentions what the problem is and what kind of measures are being taken, and discusses the future challenges. It clarifies the features of the hydrogeology of the power plant region, while showing its pictures and geological cross-section view. Next, it describes the site where the contaminated water is stored and stored structure, the accumulated amount and leakage of the contaminated water, and explains the impact of groundwater problems on the decommissioning schedule. It also introduces groundwater measures, such as seaside impervious wall, land side impervious wall, fading, groundwater bypass, etc. (A.O.)

Trend of nuclear power development in main countries and perspective of nuclear industry after the Fukushima Daiichi accident

International Nuclear Information System (INIS)

Murakami, Tomoko

2011-01-01

Fukushima Daiichi Accident occurred in March 11, 2011 was of highest interest in the world and had been reported worldwide from relevant Japanese organizations almost in real time just after happened. This article overviewed five month's response of government and energy related organization of each country and international agency and summarized effects of the accident on nuclear power in energy policy of each country as well as perspective of nuclear industry responded to change of market trend. After the accident, basic policy to regard nuclear power as important was maintained with enhancing reactor safety against extreme events in countries choosing nuclear power as important and requisite energy and there appeared such a trend of nuclear power phase-out in countries promoting nuclear power prudently. Choice of nuclear power would be decided on energy state of each country and was not affected before and after the accident. Trend of nuclear business was closely related with that of market and no fundamental change was observed although some industries with revenue from business in nuclear power phase-out country or cancelled project after the accident were obliged to be affected. (T. Tanaka)

The economics of nuclear decontamination: assessing policy options for the management of land around Fukushima dai-ichi

International Nuclear Information System (INIS)

Munro, Alistair

2013-01-01

Highlights: • Assesses land management options after the Fukushima accident. • Builds a model for exploring intervention and decontaminations options in areas affected by radioactive contamination. • Findings suggest delaying decontamination efforts by 3–10 years is optimal with a central figure of 8.75 years. • Results are sensitive to estimates of the benefits of resettlement. • Poor state of knowledge about some variables that are key for policy actions, such as psychological benefits and costs of resettlement. -- Abstract: In the light of the Japanese government's intensive efforts to decontaminate areas affected by radioactive Caesium from Fukushima dai-ichi nuclear power plant, I create a framework for assessing the merits of management options. In particular I consider delayed intervention as a possible policy. Delay can be optimal because allowing the natural decay of radiation can lower significantly the costs of achieving targets for exposure. Using some benchmark data for Japan I estimate that optimal delay is positive for most reasonable parameter values. Optimal delay generally lies in the range of 3–10 years with a central figure of 8.8 years. There is however considerable uncertainty over some of the key parameter values, particularly with regard to the behaviour of currently evacuated inhabitants

Determination of radiostrontium released from Fukushima Daiichi Nuclear Power Plant through extraction chromatography and liquid scintillation counting

International Nuclear Information System (INIS)

Maekawa, Akihiro; Momoshima, Noriyuki; Sugihara, Shinji; Tamari, Toshiya

2013-01-01

Two soil samples were collected on April 18-20, 2011 at Namie town and Tomioka town, which are located 26 km northwest and 11 km south of the Fukushima Daiichi Nuclear Power Plant, respectively. A 0-1 cm soil layer was used for analysis to determine the presence of radiostrontium. The soil was ashed, acid-digested, and strontium was separated from interference with use of an extraction chromatography resin (Sr resin, Eichrom Technologies). The isolation and purification of strontium from matrix components can be completed in 12 h. After 2 weeks for ingrowth of "9"0Y, measurements of a beta-ray of "9"0Y and "8"9"+"9"0Sr were conducted with a low-background liquid-scintillation counter for 1200 min. The concentration of "9"0Sr was determined to be 57.4 ± 1.0 and 10.1 ± 0.4 Bq kg"-"1 for Namie town and Tomioka town, respectively. "8"9Sr was not detected in either sample. The extraction chromatography method was successfully applied to determine the level of radiostrontium in the contaminated soil. When 2 g of soil is used, the detection limit of "9"0Sr is evaluated to be 2.7 Bq kg"-"1 under a chemical yield of strontium of 70%. (author)

Design Safety Considerations for Water Cooled Small Modular Reactors Incorporating Lessons Learned from the Fukushima Daiichi Accident

International Nuclear Information System (INIS)

2016-03-01

The global future deployment of advanced nuclear reactors for electricity generation depends primarily on the ability of nuclear industries, utilities and regulatory authorities to further enhance their reliability and economic competitiveness while satisfying stringent safety requirements. The IAEA has a project to help coordinate Member States efforts in the development and deployment of small and medium sized or small modular reactor (SMR) technology. This project aims simultaneously to facilitate SMR technology developers and potential SMR uses, particularly States embarking on a nuclear power programme, in identifying key enabling technologies and enhancing capacity building by resolving issues relevant to deployment, including nuclear reactor safety. The objective of this publication is to explore common practices for Member States, which will be an essential resource for future development and deployment of SMR technology. The accident at the Fukushima Daiichi nuclear power plant was caused by an unprecedented combination of natural events: a strong earthquake, beyond the design basis, followed by a series of tsunamis of heights exceeding the design basis tsunami considered in the flood analysis for the site. Consequently, all the operating nuclear power plants and advanced reactors under development, including SMRs, have been incorporating lessons learned from the accident to assure and enhance the performance of the engineered safety features in coping with such external events

Investigation of radionuclide distribution using aircraft for surrounding environmental survey from Fukushima Dai-ichi Nuclear Power Plant

International Nuclear Information System (INIS)

Torii, Tatsuo; Sanada, Yukihisa; Shikaze, Yoshiaki; Takahashi, Masaki; Ishida, Mutsushi; Nishizawa, Yukiyasu; Urabe, Yoshimi; Sugita, Takeshi; Kondo, Atsuya

2012-12-01

We carried out aerial radiation monitoring (ARM) of all Japan area in order to investigate the influence of the radio cesium which was emitted into the atmosphere by disaster of the Fukushima Dai-ichi nuclear power plant of Tokyo Electric Power Co., Inc. AMS can measure a gamma ray quickly by flight from 300 m height above the ground. Moreover, ARM has an advantage which can grasp self-possessed quantity distribution of an air dose rate and radioactive cesium in f ield , and is visually intelligible. Although there were apparatus and the technique of ARM in our country, sufficient preparations for wide area monitoring were not made. Therefore, it fixed based on the method of the U.S. Department of Energy (DOE) about the method of the conversion to all radiation dose, and the conversion method to radiocesium deposition and the method of mapping. It is possible to discriminate from a background (cosmic-ray, self-contamination and natural nuclides) at the time of western-part-of-Japan measurement by improving of the method in parallel to data acquisition. By this monitoring, it was able to check about the distribution situation of the air dose rate of the Japanese whole region, or the radioactive cesium deposition. Here, the measurement technique and a result are described. (author)

Iodine-129 depth profiles in soil within 30 km from Fukushima Daiichi Nuclear Power Plant

International Nuclear Information System (INIS)

Honda, M.; Matsuzaki, H.; Tsuchiya, Y.S.; Nakano, C.; Yamagata, T.; Nagai, H.; Matsushi, Y.; Maejima, Y.

2013-01-01

Iodine-129 depth profiles of 13 soil cores were analyzed by AMS to evaluate the distribution and the mobility in soil. The cores were sampled from various fields around the Fukushima Daiichi Nuclear Power Plant (FDNPP). Four cores out of the 13 were collected from almost the same position in Kawauchi village crop field 20 km apart from FDNPP at different times between April 2011 and June 2012 to observe the temporal variation of depth profile of "1"2"9I in soil. On the all of 13 soil cores, clear enhancement of the accident origin "1"2"9I was observed. From the crop field soil cores in Kawauchi village, "1"2"9I inventory was estimated as 43.4±2.7 mBq m"-"2 (3.10x10"1"3 atoms m"-"2). There is positive relationship between relaxation length and the elapsed time since the FDNPP accident. The increase rate of the relaxation length is about 1 cm yr"-"1 which should reflect the downward transfer rate of the Fukushima-derived "1"2"9I. Other 9 cores were collected from various fields including crop fields and man-made soils within 30 km from FDNPP on June 2012. Cumulative "1"2"9I inventory fraction [%] from the surface was calculated. The inventory fraction within top 5 cm varied widely, 65-100% with median 82%. Similarly the inventory fraction within top 10 cm varied 82 to 100% with the median 95%. (author)

Aftermath of the Fukushima Daiichi nuclear accident in March 2011 - Situation review in March 2016

International Nuclear Information System (INIS)

2016-03-01

The first part of this detailed report addresses the consequences of the accident regarding nuclear safety. It proposes a situation review of site damaged installations, of radioactive water management, and of underground water management. It presents and comments lessons learned from this accident for French nuclear installations, gives an overview of researches performed by the IRSN in the field of nuclear safety. The second part addresses health consequences of the accident. It discusses an assessment of epidemiologic studies performed on inhabitants of the Fukushima Prefecture, and comments the situation of workers involved in operations performed in the Fukushima Daiichi nuclear power plant. The third part addresses environmental consequences. It discusses values of radionuclide concentrations in Japanese air five years after the accident, measurements of caesium activities, assessments of contamination of Japanese food products, decontamination actions and waste management, the status of marine contamination in 2015, the evolution of evacuation areas between 2011 and 2016, the first returns and wills to return of evacuated populations, the update of knowledge related to the dispersion and depositions of atmospheric releases of the accident, and the modelling of atmospheric transport and fallouts of releases emitted during the accident. The last part proposes a comparison between the Chernobyl accident and the Fukushima accident in terms of distribution of radioactive depositions within river basins, of knowledge drawn from ecologic studies on fauna and flora performed on the long term in contaminated areas, and of management of forest environments after a nuclear accident

Condensate demineralizer system for Fukushima Daiichi Nuclear Power Station, the Tokyo Electric Power Co., Inc

International Nuclear Information System (INIS)

Ariyoshi, Shigeki; Ikeda, Yukio; Kuramoto, Kenji; Omori, Yoshi; Yamamoto, Hiroyoshi

1975-01-01

This paper describes the condensate demineralizing equipment recently supplied to the second, third, and fifth power units of the Fukushima Daiichi Nuclear Power Station of the Tokyo Electric Power Company, Inc. The output of this equipment is rated as 4,900 m 3 /h each, which is currently the largest capacity for this type of equipment in Japan. The purpose of this equipment is to remove any ion components and suspended solids contained in condensate to improve its water purity. By doing so, decreasing the corrosion rate of materials used in the plant and, at the same time, decreasing the radioactivity of the condensate, thus easing the whole plant operation can be achieved. The same kind of equipment is also employed at the conventional thermal power stations, but the required functioning and operating mode are quite different. In the case of the nuclear power plant, extremely severe requirements specific with nuclear technology must be met which arise solely from dealing with radioactive substances. Not only the water treatment method, but also layout and arrangement, operation and liquid waste processing methods differ from those for the conventional power plants. The equipment for the sixth unit at Fukushima is now under designing and that for the Tokai No.2 unit of the Japan Atomic Power Company is already under shop fabrication. Both have the rated capacity of 7,300 m 3 /h each, which exceeds far up the capacity of the previously mentioned equipment. (auth.)

Advances in global development and deployment of small modular reactors and incorporating lessons learned from the Fukushima Daiichi accident into the designs of engineered safety features of advanced reactors

International Nuclear Information System (INIS)

Hadid Subki, M.; )

2014-01-01

The IAEA has been facilitating the Member States in incorporating the lessons-learned from the Fukushima Dai-ichi Accident into the designs of engineered safety features of advanced reactors, including small modular reactors. An extended assessment is required to address challenges for advancing reactor safety in the new evolving generation of SMR plants to preserve the historic lessons in safety, through: assuring the diversity in emergency core cooling systems following loss of onsite AC power; ensuring diversity in reactor depressurization following a transient or accident; confirming independence in reactor trip and safety systems for sensors, power supplies and actuation systems, and finally diversity in maintaining containment integrity following a severe accident

Research with radiation and radioisotopes to better understand plant physiology and agricultural consequences of radioactive contamination from the Fukushima Daiichi nuclear accident.

Science.gov (United States)

Nakanishi, Tomoko M

2017-01-01

Research carried out by me and my group over the last almost four decades are summarized here. The main emphasis of my work was and continues to be on plant physiology using radiation and radioisotopes. Plants live on water and inorganic elements. In the case of water, we developed neutron imaging methods and produced 15 O-labeled water (half-life 2 min) and applied them to understand water circulation pattern in the plant. In the case of elements, we developed neutron activation analysis methods to analyze a large number of plant tissues to follow element specific distribution. Then, we developed real-time imaging system using conventional radioisotopes for the macroscopic and microscopic observation of element movement. After the accident in Fukushima Daiichi nuclear power plant, we, the academic staff of Graduate School, have been studying agricultural effects of radioactive fallout; the main results are summarized in two books published by Springer.

Research with radiation and radioisotopes to better understand plant physiology and agricultural consequences of radioactive contamination from the Fukushima Daiichi nuclear accident

International Nuclear Information System (INIS)

Nakanishi, T.M.

2017-01-01

Research carried out by me and my group over the last almost four decades are summarized here. The main emphasis of my work was and continues to be on plant physiology using radiation and radioisotopes. Plants live on water and inorganic elements. In the case of water, we developed neutron imaging methods and produced 15 O-labeled water (half-life 2 min) and applied them to understand water circulation pattern in the plant. In the case of elements, we developed neutron activation analysis methods to analyze a large number of plant tissues to follow element specific distribution. Then, we developed real-time imaging system using conventional radioisotopes for the macroscopic and microscopic observation of element movement. After the accident in Fukushima Daiichi nuclear power plant, we, the academic staff of Graduate School, have been studying agricultural effects of radioactive fallout; the main results are summarized in two books published by Springer. (author)

A science writer' view about the information the public looked for after the Fukushima Daiichi nuclear power plant accident

International Nuclear Information System (INIS)

Matsunaga, Waki

2012-01-01

The public was confused at a lot of information after the Fukushima Daiichi nuclear power plant accident. Especially, they were perplexed about effects of low-dose radiation exposure, because expert opinions varied with regard to safety and danger. Politicians and mass media insisted that irrational behaviors of the public caused unnecessary damages. But they were unable to understand the radiation health risk, so it was natural that the feelings of uncertainty intensified affective reactions and invited chaos. They worried about food and water contamination in spite of the low levels of monitoring data. That's why the government set very low regulation values for radioactivity in foods and drink without consideration of the principle of optimization that the International Commission on Radiological Protection had recommended. Although the concept of optimization is very important for understanding and management of the risks after this disaster, the government and many scientists did not explain about it. I think the provision of various kinds of information on both risks and socio-economic effects of various activities in society could enhance the interest of the public in the radiation risk and its management strategy, and contribute to the understanding the concept of optimization. (author)

Considering lessons learned about safety culture and their reflection to activity. After Fukushima Daiichi Nuclear Power Plant accident experience

International Nuclear Information System (INIS)

Obu, Etsuji; Hamada, Jun; Fukano, Takuya

2011-01-01

Fukushima Daiichi Nuclear Power Plant accident forced neighboring residents to evacuate for a long time and gave Public anxieties greatly and significant effects to social activities in Japan. Public trust of nuclear power was lost by not preventing the accident and future of nuclear power became reconsidered, which nuclear industry people regretted deeply. Japan Nuclear Technology Institute (JANTI) had conducted activities enhancing safety culture in nuclear industry. It would be necessary to consider improvements of accident prevention and mitigation measures after evaluating the accident in a viewpoint of 'safety culture'. Based on published information and knowledge accumulated by activities of JANTI, the accident was examined taking account of greatness of nuclear accident and its effects from the side of safety culture. Lessons learned about safety culture were pointed out as; (1) reconfirmation of specialty of nuclear technology. (2) reinforcement of questioning and learning attitudes and (3) improvement of evaluation capability of nuclear safety and safety assurance against external event. These were reflected in activities such as; (1) reconsideration of safety culture assessment, (2) strengthening further support to improve safety culture consciousness and (3) improvement of peer review activity. (T. Tanaka)

Fukushima Daiichi. Post accident countermeasures and mid-and-long-term action plan

International Nuclear Information System (INIS)

Yamashita, Kazuhiko

2012-01-01

Since accident at Fukushima Daiichi nuclear power station, TEPCO had made strenuous efforts to maintain stable cooling of reactors and suppress discharge of radioactive materials under the cooperation of the government and others concerned. Various activities towards settlement of the accident had been done according to the roadmap proposed on April 17, 2011. This article described outlines of post accident countermeasures and current activities toward decommissioning based on mid-and-long-term action plan. Step 2 completion in roadmap towards settlement of the accident was confirmed on Dec. 16, 2011; (1) reactors: attainment of a condition equivalent to 'cold shutdown' with temperature of RPV bottom below 100degC, release of radioactive materials from PCV under control and public radiation exposure by additional release being significantly held down (evaluated as maximum 0.2 mSv/y at the site boundary), and mid-term safety of circulating water injection cooling system, (2) spent fuel pools: more stable cooling with circulating cooling system by installation of heat exchanger, (3) radioactive contaminated water: reduction of total amount with full-fledged processing facilities, desalination processing (reuse), storage and mitigation of contamination in the ocean, (4) commence construction of water shielding wall to prevent contamination of the ocean via the underground water, (5) installation of reactor building cover of unit 1 to restrain release of radioactive materials, and others. According to mid-to-long-term roadmap towards the decommissioning of Fukushima Nuclear Power Units 1-4, current activities were to (1) maintain stable reactor cooling and accumulated water processing and improve their credibility, (2) reduce the radiation impact due to additional emissions from the whole site and radioactive waste generated after the accident, (3) commence removal of fuel from the spent fuel pools (unit 4 within 2 years), (4) commence R and D and decontamination the

Environmental behavior of the radionuclides released from the Fukushima Daiichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Yamazaki, Hideo

2014-01-01

The environmental behavior of radioactive nuclides released from the Fukushima Daiichi Nuclear Power Station (FDNPS) accident in eastern Japan was investigated. The radioactive pollution of environmental samples, including airborne dust, soil, sediment, fish, and other organisms was described. It was evaluated for environmental behavior and fate of the radioactive material from the spatial and temporal distribution of the radioactive nuclides. In Higashiosaka City about 600 km away from FDNPS, it begins to detect the radioactive nuclides in the airborne dust from 25th March 2011. Radioactive fission products 95 Zr- 95 Nb was detected on 18th April. The concentrations of 131 I, 134 Cs, and 137 Cs in the soil collected from Fukushima City were 126000, 14000, and 14200 Bq/kg on 19th March 2011 and 12800, 13200, and 13700 Bq/kg on 26th March 2011, respectively. The concentrations of 131 I, 134 Cs, and 137 Cs in the soil samples collected from March-June 2011 from study sites in metropolitan area and Kanto region ranged from nd to 91900, 59 to 16100, and 69 to 17600 Bq/kg, respectively. (Concentrations of 131 I were done decay correction to the value of 16th March) Radioactivities in fish samples collected from off FDNPS, Tokyo Bay, and Kejonuma Pond were measured. The radioactive contamination of forest ecosystem was also investigated. Two processes are involved in the radioactive contamination of the environment from the FDNPS accident. One is contamination by radioactive nuclides released from the hydrogen explosion. Leakage of contaminated cooling water to the ocean is in other important environmental pollution. We must continue carefully monitoring of radioactive nuclides in the environment. (author)

Synthesis of the available information about the radioactive contamination of the Japanese terrestrial environment caused by the Fukushima Dai-ichi accident - September 27, 2011; Synthese des informations disponibles sur la contamination radioactive de l'environnement terrestre japonais provoquee par l'accident de Fukushima Dai-ichi. 27 septembre 2011

Energy Technology Data Exchange (ETDEWEB)

NONE

2011-09-27

The French institute of radiation protection and nuclear safety (IRSN) collects and analyses regularly the published data concerning the contamination of the Japanese terrestrial environment caused by the Fukushima Dai-ichi power plant accident. This synthesis presents a status of the data recently obtained since the previous similar notes of April 12, May 25 and July 13. The note presents the detailed activity analysis of several surface soil samples, a mapping of {sup 137}Cs, {sup 134}Cs and {sup 131}I activities with the spatial distribution of samplings in the 20, 30, 80 and 100 km areas around the damaged power plant, the contamination of agriculture food products and a focus on some vegetable products showing a significant contamination, like tea leaves, 'yuzu' fruits, figs and rice. Some other products, like meat, fungi and some milk products show cesium contamination levels above the Japanese standards while cesium and iodine are no longer detected in drinking water. (J.S.)

Strengthening safety of nuclear power by learning lessons from the accident at TEPCO's Fukushima-Daiichi Nuclear Power Plant

International Nuclear Information System (INIS)

Omoto, Akira

2011-01-01

The paper first discusses ongoing onsite stabilization activities at Fukushima-Daiichi NPP and a plan for onsite and offsite remedial actions including decontamination and defueling. Four key lessons learned (LL) are raised; safety regulation and safety culture, workable/executable severe accident management procedure, crisis management and design. Global actions for strengthening safety in post-Fukushima era would be built around the IAEA action plan, under recognition of national responsibility. For specific country and plant, a combination of the following may help; a) overall assessment of safety and reflection of Fukushima LL in the light of principles in INSAG-12, b) specific plant assessment of risks from internal, external and security-related events for identifying vulnerabilities and continuous safety improvement, and c) international peer review for comprehensiveness, objectivity and confidence building. In this context, the followings could be worth receiving attention; a) to revisit defense-in-depth, while utilizing risk information, for its completeness and effectiveness (especially, strengthened defense against environmental contamination by effective combination of provisions and management as well as attentiveness and careful attitude towards uncertainties across all layers of defense-in-depth), b) to restore public confidence, c) to cooperate for safety infrastructure in newcomers, d) to build internationally harmonized and cooperative scheme for liability. (author)

Effects of radionuclide contamination on forest trees in the exclusion zone around the Fukushima Daiichi Nuclear Power Plant

International Nuclear Information System (INIS)

Watanabe, Yoshito; Kubota, Yoshihisa; Fuma, Shoichi; Yoshida, Satoshi; Ichikawa, San'ei; Kubota, Masahide; Takano, Toshiyuki; Mizoguchi, Masahiko

2012-01-01

A preliminary survey was performed for forest areas within the exclusion zone around the Fukushima Daiichi Nuclear Power Plant, for radionuclide contamination levels and radiation effects on trees during the first year after the March 2011 accident. Even in the most contaminated forest, approximately 3 km west of the power plant, no externally visible symptoms of radiation damage—including yellowing, malformation, and early withering of leaves—were observed in trees, indicating that massive radiation damage did not occur in the surrounding forests after the accident. Radiosensitive coniferous plants were, however, heavily contaminated by the deposition of radionuclides in reproductive organs such as cones, which could cause the exposure of developing seeds. The level of radionuclides in the cones of Japanese cedar trees changed, depending on the contamination level of the forest, which was approximately given by an ambient dose rate. The dose rate of internal exposure in the cones of the most contaminated forest, which was calculated to include exposure from the radionuclides deposited in the organs, was found to be within the criteria dose rate of 4-40 μGy/h selected for pine trees by the ICRP in Publication 108. This raises the necessity of performing more detailed analyses of the cytogenetic and reproductive damage to forest trees in the area. (author)

Effects of radionuclide contamination on forest trees in the exclusion zone around the Fukushima Daiichi Nuclear Power Plant

International Nuclear Information System (INIS)

Watanabe, Yoshito; Kubota, Yoshihisa; Fuma, Shoichi; Yoshida, Satoshi; Ichikawa, San'ei; Kubota, Masahide; Takano, Toshiyuki; Mizoguchi, Masahiko

2013-01-01

A preliminary survey was performed for forest areas within the exclusion zone around the Fukushima Daiichi Nuclear Power Plant, for radionuclide contamination levels and radiation effects on trees during the first year after the March 2011 accident. Even in the most contaminated forest, approximately 3 km west of the power plant, no externally visible symptoms of radiation damage—including yellowing, malformation, and early withering of leaves—were observed in trees, indicating that massive radiation damage did not occur in the surrounding forests after the accident. Radiosensitive coniferous plants were, however, heavily contaminated by the deposition of radionuclides in reproductive organs such as cones, which could cause the exposure of developing seeds. The level of radionuclides in the cones of Japanese cedar trees changed, depending on the contamination level of the forest, which was approximately given by an ambient dose rate. The dose rate of internal exposure in the cones of the most contaminated forest, which was calculated to include exposure from the radionuclides deposited in the organs, was found to be within the criteria dose rate of 4-40 μGy/h selected for pine trees by the ICRP in Publication 108. This raises the necessity of performing more detailed analyses of the cytogenetic and reproductive damage to forest trees in the area. (author)

Assessment of radiation doses to the public in areas contaminated by the Fukushima Daiichi Nuclear Power Station accident

International Nuclear Information System (INIS)

Takahara, Shogo; Iijima, Masashi; Shimada, Kazumasa; Kimura, Masanori; Homma, Toshimitsu

2013-01-01

In the areas contaminated by radioactive materials due to the Fukushima Daiichi Nuclear Power Station accident, many residents are exposed to radiation through various exposure pathways. Dose assessment is important for providing appropriate protection to the people and clarifying the impact of the accident. The aim of this study is to provide preliminary results of the assessment of radiation doses received by the inhabitants of Fukushima Prefecture. To assess the doses realistically and comprehensively, a probabilistic approach was adopted using data that reflected realistic environmental trends and lifestyle habits in Fukushima Prefecture. In the first year after the contamination, the 95th percentile of the annual effective dose received by the inhabitants evacuated from the evacuation areas and the deliberate evacuation areas was mainly in the 1-10 mSv dose band. However, the 95th percentile of the dose received by some outdoor workers and inhabitants evacuated from highly contaminated areas was in the 10-50 mSv dose band. The doses due to external exposure to deposited radionuclides were the dominant exposure pathway, and their contributions were about 90% under prevailing contamination conditions in Fukushima Prefecture. In addition, 20%-30% of the lifetime effective dose was delivered during the first year after the contamination. (author)

Atmospheric discharge and dispersion of radionuclides during the Fukushima Dai-ichi Nuclear Power Plant accident. Part I: Source term estimation and local-scale atmospheric dispersion in early phase of the accident

International Nuclear Information System (INIS)

Katata, Genki; Ota, Masakazu; Terada, Hiroaki; Chino, Masamichi; Nagai, Haruyasu

2012-01-01

The atmospheric release of 131 I and 137 Cs in the early phase of the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) accident from March 12 to 14, 2011 was estimated by combining environmental data with atmospheric dispersion simulations under the assumption of a unit release rate (1 Bq h −1 ). For the simulation, WSPEEDI-II computer-based nuclear emergency response system was used. Major releases of 131 I (>10 15 Bq h −1 ) were estimated when air dose rates increased in FNPP1 during the afternoon on March 12 after the hydrogen explosion of Unit 1 and late at night on March 14. The high-concentration plumes discharged during these periods flowed to the northwest and south–southwest directions of FNPP1, respectively. These plumes caused a large amount of dry deposition on the ground surface along their routes. Overall, the spatial pattern of 137 Cs and the increases in the air dose rates observed at the monitoring posts around FNPP1 were reproduced by WSPEEDI-II using estimated release rates. The simulation indicated that air dose rates significantly increased in the south–southwest region of FNPP1 by dry deposition of the high-concentration plume discharged from the night of March 14 to the morning of March 15. - Highlights: ► Source term during the Fukushima Dai-ichi Nuclear Power Plant accident was estimated. ► Atmospheric dispersion simulation was carried out for estimation. ► Major releases were estimated in the afternoon on March 12 and the night on March 14. ► Air dose rate increased due to dry deposition during the night of March 14.

Dose rate survey inside and outside three public buildings located approximately 40 km northwest of the Fukushima Daiichi Nuclear Power Stations

International Nuclear Information System (INIS)

Yajima, Kazuaki; Iwaoka, Kazuki; Kamada, So

2013-01-01

We surveyed the reduction of the dose rate inside three public buildings compared to the dose rate outside in Kawamata-machi, Fukushima Prefecture. The three buildings—a wooden construction district meeting place, a steel construction public hall, and a reinforced concrete school building—are located approximately 40 km northwest of TEPCO's Fukushima Daiichi Nuclear Power Stations. The dose rate measurement, performed with a NaI(Tl) scintillation survey meter, was carried out on January 19, 2012. We evaluated the reduction of the dose rate inside the building using the reduction factor, which was determined to be the ratio of the dose rate inside the building to that outside the building. The reduction factors 1 m inside from the window were 0.51-0.56 for the wooden building, 0.34-0.51 for the steel construction building, and 0.27-0.31 for the concrete building. The reduction factors at the center of the room were 0.48 for the wooden building, 0.23-0.34 for the steel construction building, and 0.10-0.16 for the concrete building. (author)

Birth Outcomes after the Fukushima Daiichi Nuclear Power Plant Disaster: A Long-Term Retrospective Study

Directory of Open Access Journals (Sweden)

Claire Leppold

2017-05-01

Full Text Available Changes in population birth outcomes, including increases in low birthweight or preterm births, have been documented after natural and manmade disasters. However, information is limited following the 2011 Fukushima Daiichi Nuclear Power Plant Disaster. In this study, we assessed whether there were long-term changes in birth outcomes post-disaster, compared to pre-disaster data, and whether residential area and food purchasing patterns, as proxy measurements of evacuation and radiation-related anxiety, were associated with post-disaster birth outcomes. Maternal and perinatal data were retrospectively collected for all live singleton births at a public hospital, located 23 km from the power plant, from 2008 to 2015. Proportions of low birthweight (<2500 g at birth and preterm births (<37 weeks gestation at birth were compared pre- and post-disaster, and regression models were conducted to assess for associations between these outcomes and evacuation and food avoidance. A total of 1101 live singleton births were included. There were no increased proportions of low birthweight or preterm births in any year after the disaster (merged post-disaster risk ratio of low birthweight birth: 0.98, 95% confidence interval (CI: 0.64–1.51; and preterm birth: 0.68, 95% CI: 0.38–1.21. No significant associations between birth outcomes and residential area or food purchasing patterns were identified, after adjustment for covariates. In conclusion, no changes in birth outcomes were found in this institution-based investigation after the Fukushima disaster. Further research is needed on the pathways that may exacerbate or reduce disaster effects on maternal and perinatal health.

Dose assessment for emergency workers in early phase of Fukushima Daiichi nuclear power plant accident

Energy Technology Data Exchange (ETDEWEB)

Sadeghi, Nahid; Ahangari, Rohollah; Kasesaz, Yaser; Noori-kalkhoran, O. [Nuclear Science and Technology Research Institute (NSTRI), Tehran (Iran, Islamic Republic of). Reactor Research School

2017-11-15

In the case of Fukushima Daiichi nuclear power plant (FNP) accident, the radioactive material was released from reactor units 1-3 and transported to short and long distances due to the atmospheric pathways-motions. Power sources for monitoring posts were lost due to earthquake and tsunami. Based on air dose rates and other data measured by monitoring cars, the amount of radioactive material released to the atmosphere from the power station was obtained. The atmospheric dispersion and the transport model used in the RASCAL code, estimate the radionuclide concentrations downwind, both in the air and on the ground due to deposition. The calculated concentrations are then used to estimate the projected doses for workers in vicinity of the accident area in the first minutes of accident time. For dose modeling, we assumed that each worker was 15 min in vicinity of FNP in accident situation, once without and once with protective clothes or respirator. According to Tokyo Electric Power Company (TEPCO) report six workers had received doses over 250 mSv (309 to 678 mSv) apparently due to inhaling Iodine-131 fume. In this paper the calculated dose results using RASCAL code shows that, if emergency workers who work in early phase of accident had not used protective equipment, for 15 min, inhalation doses from iodine in their thyroid gland up to 12 March afternoon would have been 520 mSv. A comparison between calculation results and TEPCO report shows that dose calculated virtually is nearly equal to TEPCO measurement results.

Estimation of internal exposure dose from food after the Fukushima Daiichi Nuclear Power Station disaster

International Nuclear Information System (INIS)

Takizawa, Mari; Yoshizawa, Nobuaki; Kawai, Masaki; Miyatake, Hirokazu; Hirakawa, Sachiko; Murakami, Kana; Sato, Osamu; Takagi, Shunji; Suzuki, Gen

2016-01-01

In order to estimate the internal exposure dose from food due to the Fukushima Daiichi Nuclear Power Station accident, total diet study (TDS) has been carried out. TDS is a method for estimating how much of certain chemicals people intake in the normal diet. A wide range of food products are chosen as targets, and the increase or decrease of chemicals depending on processing or cooking is taken into account. This paper glanced at the transition of TDS survey results, and with a focus on the survey results of the market basket (MB) system, which is one of the TDS techniques, it examined a decrease in the committed effective dose per year of radioactive cesium. Although the values of internal exposure dose from food in Fukushima Prefecture and surrounding prefectures are even now in a relatively high tendency compared with those in the distant regions, the difference has been narrowing. According to the attenuation prediction of internal exposure dose in each region of Fukushima Prefecture, the values after 5 years from the accident will be lower than the measured value on the food in market that has been investigated during 1989 and 2005. In addition, the internal exposure dose that was the survey results based on MB system in September - October 2014 was 0.0007 to 0.0022 mSv/year. These values are very small at 1% or less of the upper limit dose of 1 mSv/year as the setting basis of current reference value in Japan. (A.O.)

The relationship between media consumption and health-related anxieties after the Fukushima Daiichi nuclear disaster.

Science.gov (United States)

Sugimoto, Amina; Nomura, Shuhei; Tsubokura, Masaharu; Matsumura, Tomoko; Muto, Kaori; Sato, Mikiko; Gilmour, Stuart

2013-01-01

The Fukushima Daiichi nuclear disaster caused a global panic by a release of harmful radionuclides. In a disaster setting, misusage of contemporary media sources available today can lead to disseminated incorrect information and panic. The study aims to build a scale which examines associations between media and individual anxieties, and to propose effective media usages for future disaster management. The University of Tokyo collaborated with the Fukushima local government to conduct a radiation-health-seminar for a total of 1560 residents, at 12 different locations in Fukushima. A 13 item questionnaire collected once before and after a radiation-seminar was used on factor analysis to develop sub-scales for multiple regression models, to determine relationships between the sub-scales and media type consumed. A paired t-test was used to examine any changes in sub-scale of pre- and post-seminar scores. Three sub-scales were revealed and were associated with different media types: was with rumors, while concern for the future was positively associated with regional-newspapers and negatively with national-newspapers. Anxiety about social-disruption was associated with radio. The seminar had a significant effect on anxiety reduction for all the three sub-scales. Different media types were associated with various heightened concerns, and that a radiation seminar was helpful to reduce anxieties in the post-disaster setting. By tailoring post-disaster messages via specific media types, i.e., radio, it may be possible to effectively convey important information, as well as to calm fears about particular elements of post-disaster recovery and to combat rumors.

Evaluation of radioactive decontamination effect for paddy soil contaminated by the Fukushima Daiichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Imaizumi, Masayuki; Yoshimoto, Shuhei; Ishida, Satoshi; Okushima, Shuji; Yuuki, Youichi; Hirata, Ryoji

2016-01-01

The National Institute for Rural Engineering performed decontamination of radioactivity at the experimental sites in Iitate Village where paddy fields were contaminated by the Fukushima Daiichi nuclear power plant accident in March 2011 by means of three methods as follows; (1) topsoil removal using soil hardener, (2) removal of soil after paddling with water draining suspended contaminated soil by pumping without manual assistance, and (3) removal of soil after paddling with water draining suspended contaminated soil by pumping with manual assistance. The three methods were evaluated using decontamination factors (DFs) that were determined by applying a variant of inverse analysis using the calculation system for the estimation of decontamination effects (CDE). Input data were provided by surveys using a low-level balloon and a radio-controlled helicopter. The DF values of the three methods were determined on the basis of the Euclidean distances between the simulated and measured dose rates after decontamination. The resulting DFs were > 60 for topsoil removal using soil hardener, 1.4 for slurry pumping, and 2.2 for manually assisted slurry pumping. The area decontaminated by the soil hardening method may have been fully decontaminated, because the distribution of measured dose rates was consistent with the distribution of dose rates calculated for a fully decontaminated area within 20 m in radius. (author)

Caesium-rich micro-particles: A window into the meltdown events at the Fukushima Daiichi Nuclear Power Plant

Science.gov (United States)

Furuki, Genki; Imoto, Junpei; Ochiai, Asumi; Yamasaki, Shinya; Nanba, Kenji; Ohnuki, Toshihiko; Grambow, Bernd; Ewing, Rodney C.; Utsunomiya, Satoshi

2017-02-01

The nuclear disaster at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011 caused partial meltdowns of three reactors. During the meltdowns, a type of condensed particle, a caesium-rich micro-particle (CsMP), formed inside the reactors via unknown processes. Here we report the chemical and physical processes of CsMP formation inside the reactors during the meltdowns based on atomic-resolution electron microscopy of CsMPs discovered near the FDNPP. All of the CsMPs (with sizes of 2.0-3.4 μm) comprise SiO2 glass matrices and ~10-nm-sized Zn-Fe-oxide nanoparticles associated with a wide range of Cs concentrations (1.1-19 wt% Cs as Cs2O). Trace amounts of U are also associated with the Zn-Fe oxides. The nano-texture in the CsMPs records multiple reaction-process steps during meltdown in the severe FDNPP accident: Melted fuel (molten core)-concrete interactions (MCCIs), incorporating various airborne fission product nanoparticles, including CsOH and CsCl, proceeded via SiO2 condensation over aggregates of Zn-Fe oxide nanoparticles originating from the failure of the reactor pressure vessels. Still, CsMPs provide a mechanism by which volatile and low-volatility radionuclides such as U can reach the environment and should be considered in the migration model of Cs and radionuclides in the current environment surrounding the FDNPP.

Radiocesium contamination of the moss Hypnum plumaeforme caused by the Fukushima Dai-ichi Nuclear Power Plant accident.

Science.gov (United States)

Oguri, Emiko; Deguchi, Hironori

2018-03-07

We investigated 134 Cs and 137 Cs activity concentrations in the common Japanese moss species Hypnum plumaeforme collected from 32 sites within ca. 100 km radius of the Fukushima Dai-ichi Nuclear Power Plant. A total of 32 samples of H. plumaeforme were collected during the field surveys from November 2013 to September 2014. The maximum radiocesium activity concentrations in H. plumaeforme were 60.9 ± 1.8 kBq kg -1 for 134 Cs and 123 ± 2.3 kBq kg -1 for 137 Cs. The mean value for the 134 Cs/ 137 Cs was 1.17 ± 0.05, and the mean T ag value was 0.09 ± 0.13. Positive correlations were obtained between total 134 Cs + 137 Cs activity concentrations in H. plumaeforme and the air dose rate with a correlation coefficient (r) of 0.55 (P = 0.001), and between 137 Cs activity concentration in H. plumaeforme and 137 Cs deposition density on soil with r of 0.55 (P = 0.001). These results suggest that the perennial moss species H. plumaeforme could be more suitable and useful as a qualitative indicator for the radiocesium pollution compared to vascular plants spreading over the lowlands including human habitation in Fukushima Prefecture. Copyright © 2018. Published by Elsevier Ltd.

Radioactivity level of airplane to Guangzhou Baiyun international airport during the Fukushima Daiichi nuclear power plant accident

International Nuclear Information System (INIS)

Song Haiqing; Chen Wentao; Cheng Xiaobo; Liao Tong; Deng Fei; Chen Fuliang; Zhang Yanjin; Li Lingjuan; Liang Guiyuan; Wu Guibiao

2014-01-01

The radioactivity level of airplanes to Guangzhou Baiyun International Airport (GBIAC) during the Fukushima Daiichi nuclear power plant accident was monitored by Guangdong Environmental Radiation Monitoring Center (GERC) on March 15 and 16, 2011. The artificial radionuclide "1"3"1I, "1"3"4Cs, "1"3"7Cs, "l"3"6Cs, "1"3"2I, "1"3"2Te were detected in the wipe samples of the outer surface of airplanes from Japan to GBIAC. The radioactivity ration of "1"3"7Cs/"1"3"4Cs was calculated as (1.12 ± 0.06) in the wipe samples, which similar to the result in the wipe sample of the outer surface of airplanes from Japan to Hangzhou airport obtained by Zhejiang Province Environmental Radiation Monitoring Center (l.lO ± 0.08), but slightly higher than results in the aerosol monitoring at Guangzhou (0.99 ± 0.30) and Shenzhen (0.94 ± 0.30) by GERC, the data (0.83) published by Japan Nuclear and Industrial Safety Agency (NISA) and the result (1.00 ± 0.13) measured by Tokyo Electric Power Company. A slight radioactive contamination was detected on the surface of outer airplanes and internal cabin. The practice suggested that the wipe sample of the outer surface of airplane was a fast , simple and sensitive approach for emergency monitoring of radioactive contamination. (authors)

Geographical distribution of radioactive nuclides released from the Fukushima Daiichi Nuclear Power Station accident in eastern Japan

International Nuclear Information System (INIS)

Ishida, Masanobu; Umetsu, Kohei; Sugimoto, Miyabi; Yamaguchi, Yuta; Yamazaki, Hideo; Nakagawa, Ryota

2013-01-01

The geographical distribution of radioactive nuclides released from the Fukushima Daiichi Nuclear Power Station accident in metropolitan areas located in eastern Japan was investigated. The radioactive contamination of environmental samples, including soil and biological materials, was analyzed. The concentrations of 131 I, 134 Cs, and 137 Cs in the soil samples collected from Fukushima City were 122000, 11500 and 14000 Bq/kg on 19th March 2011 and 129000, 11000 and 13700 Bq/kg on 26th March 2011, for the three nuclides respectively. The concentrations of 131 I, 134 Cs and 137 Cs in the soil samples collected from March-June 2011 from study sites ranged from 240 to 101000, 28 to 26200, and 14 to 33700 Bq/kg, respectively. In Higashiosaka City, it began to detect those radioactive nuclides in the atmospheric airborne dust from 25th March. Radioactive fission products 95 Zr- 95 Nb were detected on 18th April 2011. Biological samples collected from Tokyo Bay were studied. The maximum concentrations of 134 Cs and 137 Cs detected in the biological samples were 12.2 and 19.2 Bq/kg, which were measured in goby. 131 I was not detected in the biological samples however, trace amounts of the short half-life nuclide 110m Ag were found in the shellfish samples. (author)

Radiocesium contamination in house dust within evacuation areas close to the Fukushima Daiichi nuclear power plant.

Science.gov (United States)

Shinohara, Naohide; Yoshida-Ohuchi, Hiroko

2018-05-01

Outdoor decontamination efforts have been ongoing since the Fukushima Daiichi nuclear power plant (FDNPP) accident; however, little is known about indoor contamination. Therefore, house dust was sampled based on particle size in 21 wooden buildings (19 residential houses and 2 community centers) within the evacuation area close to the FDNPP, Fukushima Prefecture, Japan. Activities of radiocesium ( 137 Cs) per gram of house dust increased with decreasing particle size (mean: 6.1 × 10 3 , 2.6 × 10 3 , 1.6 × 10 3 , 7.5 × 10 2 , 5.0 × 10 2 , and 4.6 × 10 2  Bq/g for house dust were inversely related to the square of distance from the FDNPP for house dust. It was found that 19%, 33%, and 48% of 137 Cs in house dust were extracted in water, 1 M HCl, and not extracted, respectively. Considering the bioaccessibility and assuming a 20 mg/day daily intake of house dust, the daily doses would be 7.2 Bq/day (mean) and 18 Bq/day (95th percent quantile). These results provide valuable insight into indoor radioactive Cs contamination in the area around the FDNPP and possible oral exposure to indoor radioactive Cs after returning home. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Communication activity for residents to understand radiation after the accident of Fukushima Daiichi Nuclear Power Station

International Nuclear Information System (INIS)

Itabashi, Kiyoshi; Tagawa, Akihiro; Sugiyama, Kenji; Yamamoto, Tomoyo

2015-01-01

'Question-and-Answer Session on Radiation and Health' ('Kotaeru-kai' in Japanese) has started in July 2011 in Fukushima Prefecture, which was influenced by the accident of Fukushima Daiichi Nuclear Power Station following the Great East Japan Earthquake and Tsunami on 11 March 2011. The purpose of the Session is to have mainly parents and teachers (kindergartens, schools etc.) understand correctly about radiation and its influence on health. At the requests of the teachers in Fukushima Prefecture, about 4 staff members made a team, and visited Fukushima. The members of the team were selected from 500 JAEA staffs nominated beforehand. The members explained about radiation and its influence on health by using illustrations and metaphors. After the lecture, they answered the questions asked in advance at schools. Also they answered the questions asked in the Session. In the Session, the members placed much value on the communication with participants. Until the end of December 2014, the Question-and-Answer Sessions on Radiation and Health have been held 241 times for about twenty thousand participants. According to 7,613 participants' questionnaires, which were collected from July 2011 to the end of 2012, it seems that participants were able to understand well about radiation and its influence on health. Besides parents and teachers, some of the junior high schools requested to explain for students. JAEA will continue this communication activity in order to meet these expectations and requirements. (author)

Physical properties, structure, and shape of radioactive Cs from the Fukushima Daiichi Nuclear Power Plant accident derived from soil, bamboo and shiitake mushroom measurements.

Science.gov (United States)

Niimura, Nobuo; Kikuchi, Kenji; Tuyen, Ninh Duc; Komatsuzaki, Masakazu; Motohashi, Yoshinobu

2015-01-01

We conducted an elution experiment with contaminated soils using various aqueous reagent solutions and autoradiography measurements of contaminated bamboo shoots and shiitake mushrooms to determine the physical and chemical characteristics of radioactive Cs from the Fukushima Daiichi Nuclear Power Plant accident. Based on our study results and data in the literature, we conclude that the active Cs emitted by the accident fell to the ground as granular non-ionic materials. Therefore, they were not adsorbed or trapped by minerals in the soil, but instead physically adhere to the rough surfaces of the soil mineral particles. Granular Cs* can be transferred among media, such as soils and plants. The physical properties and dynamic behavior of the granular Cs* is expected to be helpful in considering methods for decontamination of soil, litter, and other media. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

Achievement report for fiscal 1998. Optical tomographic system; 1998 nendo seika hokokusho. Hikari danso imaging system

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-05-01

Evaluations were given on spatial resolution and measurement time of an optical tomographic system by using the developed 64-channel time-resolved spectroscopy and an image reconstruction algorithm. With respect to the spatial resolution, the target value of 1 cm was verified from tomographic images of a phantom with a diameter of 10cm, simulating a neonate. The measurement time achieved 20 minutes, being one third of the target value. In installing the equipment at Hokkaido University, speeds of the optical switches and attenuators were increased to have reduced the measurement time to one minute. For installation at Kanagawa Rehabilitation Center, development has been made on a nano-second light pulser, whose average beam quantity has been increased to 40 times, and improvement has been given on the optical switches, the attenuators, and the indication software, by which the measurement time was decreased further by 30 seconds than that at Hokkaido University. In performing the clinical evaluation, the evaluation protocol resolved by the Experiment Evaluation Special Committee was submitted for deliberation at the Medical Welfare Device Clinical Evaluation Committee. Upon having been authorized by the Committee, the clinical evaluations were performed at Hokkaido University and the Kanagawa Rehabilitation Center. (NEDO)

Knowledge Management Learned from Decommissioning and Environmental Remediation after an Unexpected Radiological Contamination Occurred at Fukushima Dai-ichi NPP Accident

International Nuclear Information System (INIS)

Inoue, T.

2016-01-01

Full text: The Fukushima Dai-ichi Nuclear Power Plant (NPP) Accident resulted in severe damage of cores in units 1 to 3, and subsequently entailed not only contamination of facility but also widely-spread radiological contamination in environment due to the release of radioactive nuclides. Decommissioning activities will require at least 30–40 years with various stages of operation, such as contaminated water treatment, decontamination of reactor buildings, retrieval of spent fuel (SF) from SF pools, inspection of primary containment vessel (PCV) and reactor pressure vessel (RPV), and retrieval and further management of damaged fuel and melted debris. Especially, a water injection for core cooling is a pressing issue to stabilize the melted debris, which leads to produce a large amount of contaminated water. Environmental remediation is a crucial issue to return a normal life for local residents. On-site cleaning and off-site remediation produce various kinds and enormous amount of contaminated material with low to high radioactivity. Knowledge management of on-site and off-site issues over generation are critical to achieve the cleaning and remediation requiring a couple of decades. In addition, knowledge obtained through a long term-operation should be shared globally. (author

How should we handle Fukushima Daiichi Nuclear Power Station accident with engineer ethics? What is seen by encountering resilience engineering

International Nuclear Information System (INIS)

Oba, Kyoko

2017-01-01

Many of lectures on 'engineer ethics' being held at universities, etc. positively incorporate case study. This paper introduced the Fukushima Daiichi Nuclear Power Station accident (1F accident) not as a mere failure case, but with broader view and broader manner based on practice. Resilience engineering cites anticipating, monitoring, responding, and learning as four core capabilities required to realize safety that people and organizations should aim at. The authors tried to analyze 1F accident using these four core capabilities and the elements required to demonstrating these core capabilities. In the responding of TEPCO to earthquake and tsunami cases before the accident, tsunami countermeasure responding required to prevent 1F accident was not demonstrated as a result. Good examples seen in other responding are the construction of the seismic isolation important building and the deployment of fire engines to the whole nuclear power plant. Accident reports so far took viewpoints of why the accident occurred, and why it led to hydrogen explosion. However, from resilience engineering, why catastrophic conditions could be avoided and how water injection in nuclear facilities could be assured become viewpoints. (A.O.)

Fission products in National Atmospheric Deposition Program—Wet deposition samples prior to and following the Fukushima Dai-Ichi Nuclear Power Plant incident, March 8?April 5, 2011

Science.gov (United States)

Wetherbee, Gregory A.; Debey, Timothy M.; Nilles, Mark A.; Lehmann, Christopher M.B.; Gay, David A.

2012-01-01

Radioactive isotopes I-131, Cs-134, or Cs-137, products of uranium fission, were measured at approximately 20 percent of 167 sampled National Atmospheric Deposition Program monitoring sites in North America (primarily in the contiguous United States and Alaska) after the Fukushima Dai-Ichi Nuclear Power Plant incident on March 12, 2011. Samples from the National Atmospheric Deposition Program were analyzed for the period of March 8-April 5, 2011. Calculated 1- or 2-week radionuclide deposition fluxes at 35 sites from Alaska to Vermont ranged from 0.47 to 5,100 Becquerels per square meter during the sampling period of March 15-April 5, 2011. No fission-product isotopes were measured in National Atmospheric Deposition Program samples obtained during March 8-15, 2011, prior to the arrival of contaminated air in North America.

Synthesis of the available information about the radioactive contamination of the Japanese terrestrial environment caused by the Fukushima Dai-ichi accident - September 27, 2011

International Nuclear Information System (INIS)

2011-01-01

The French institute of radiation protection and nuclear safety (IRSN) collects and analyses regularly the published data concerning the contamination of the Japanese terrestrial environment caused by the Fukushima Dai-ichi power plant accident. This synthesis presents a status of the data recently obtained since the previous similar notes of April 12, May 25 and July 13. The note presents the detailed activity analysis of several surface soil samples, a mapping of 137 Cs, 134 Cs and 131 I activities with the spatial distribution of samplings in the 20, 30, 80 and 100 km areas around the damaged power plant, the contamination of agriculture food products and a focus on some vegetable products showing a significant contamination, like tea leaves, 'yuzu' fruits, figs and rice. Some other products, like meat, fungi and some milk products show cesium contamination levels above the Japanese standards while cesium and iodine are no longer detected in drinking water. (J.S.)

The relationship between media consumption and health-related anxieties after the Fukushima Daiichi nuclear disaster.

Directory of Open Access Journals (Sweden)

Amina Sugimoto

Full Text Available BACKGROUND: The Fukushima Daiichi nuclear disaster caused a global panic by a release of harmful radionuclides. In a disaster setting, misusage of contemporary media sources available today can lead to disseminated incorrect information and panic. The study aims to build a scale which examines associations between media and individual anxieties, and to propose effective media usages for future disaster management. METHODS: The University of Tokyo collaborated with the Fukushima local government to conduct a radiation-health-seminar for a total of 1560 residents, at 12 different locations in Fukushima. A 13 item questionnaire collected once before and after a radiation-seminar was used on factor analysis to develop sub-scales for multiple regression models, to determine relationships between the sub-scales and media type consumed. A paired t-test was used to examine any changes in sub-scale of pre- and post-seminar scores. RESULTS: Three sub-scales were revealed and were associated with different media types: was with rumors, while concern for the future was positively associated with regional-newspapers and negatively with national-newspapers. Anxiety about social-disruption was associated with radio. The seminar had a significant effect on anxiety reduction for all the three sub-scales. CONCLUSION: Different media types were associated with various heightened concerns, and that a radiation seminar was helpful to reduce anxieties in the post-disaster setting. By tailoring post-disaster messages via specific media types, i.e., radio, it may be possible to effectively convey important information, as well as to calm fears about particular elements of post-disaster recovery and to combat rumors.

The effect of the accident of Fukushima Daiichi Nuclear Power Plants on Niigata city based on tritium concentration in precipitation

Energy Technology Data Exchange (ETDEWEB)

Kataoka, N. [Department of Chemistry and Chemical Engineering, Faculty of Engineering, Niigata University 8050 Ikarashi 2-III ocho, Niigata-shi, Nishiku, Niigata Pref. 950-2181 (Japan); Environmental Analytical Center of Niigata Prefecture 53-1 Ojigouya, Kounan-ku, Niigata Pref. 950-1144 (Japan); Imaizumi, H.; Kano, N.; Ying, W. [Department of Chemistry and Chemical Engineering, Faculty of Engineering, Niigata University 8050 Ikarashi 2-III ocho, Niigata-shi, Nishiku, Niigata Pref. 950-2181 (Japan)

2014-07-01

The maximum value of tritium concentration in precipitation was 200 Bq/kg in Niigata city when atmospheric nuclear-bomb tests were performed in 1960s. After that, tritium concentration continuously decreased and reached to environmental revel (0.5~1.0 Bq/kg). However, after the accident of Fukushima daiichi nuclear power plants, the tritium concentration in precipitation increased in Niigata city. Therefore the observation of tritium concentration had to be carried out. In our laboratory, we have investigated the tritium concentration in precipitation and also investigated the relation between the tritium concentration and other ion (Na⁺, Mg⁺, K⁺, Ca⁺, Cl⁻, NO3⁺ or SO₄²⁻) concentration in precipitation in Niigata city. In this study, precipitation in Niigata city was gathered monthly and the evaluation of tritium concentration in precipitation was performed. In addition, we also collected the precipitation hourly (short precipitation). Each water sample thus obtained was distilled with sodium peroxide and potassium permanganate. Then the water sample thus distilled was enriched in SPE electronic enrichment apparatus, and the tritium concentration in the sample thus treated was measured in a liquid scintillation counter. On the other hand, each ion concentration in the sample was measured by ion chromatography or Atomic Absorption Spectrometry. From the above the mentioned, the following five matters can be found. (1) The tritium concentration in the samples in March and April 2011 were twice or three times higher than that in March and April in annual years. In other words, it is considered that the thus high level concentration of tritium leads to the evaluation of the effect of the accident of the Fukushima nuclear power plants on Niigata city. (2) As to the sample, the concentration of the non-sea salt Ca²⁺ (nssCa²⁺) is similar to that in March and April in annual years. (3) For each short precipitation sample collected on March 15, 2011

In-situ removal and characterisation of uranium-containing particles from sediments surrounding the Fukushima Daiichi Nuclear Power Plant

Science.gov (United States)

Martin, P. G.; Griffiths, I.; Jones, C. P.; Stitt, C. A.; Davies-Milner, M.; Mosselmans, J. F. W.; Yamashiki, Y.; Richards, D. A.; Scott, T. B.

2016-03-01

Traditional methods to locate and subsequently study radioactive fallout particles have focused heavily on autoradiography coupled with in-situ analytical techniques. Presented here is the application of a Variable Pressure Scanning Electron Microscope with both backscattered electron and energy dispersive spectroscopy detectors, along with a micromanipulator setup and electron-hardening adhesive to isolate and remove individual particles before synchrotron radiation analysis. This system allows for a greater range of new and existing analytical techniques, at increased detail and speed, to be applied to the material. Using this method, it was possible to erform detailed energy dispersive spectroscopy and synchrotron radiation characterisation of material likely ejected from the Fukushima Daiichi Nuclear Power Plant found within a sediment sample collected from the edge of the 30 km exclusion zone. Particulate material sub-micron in maximum dimension examined during this work via energy dispersive spectroscopy was observed to contain uranium at levels between 19.68 and 28.35 weight percent, with the application of synchrotron radiation spectroscopy confirming its presence as a major constituent. With great effort and cost being devoted to the remediation of significant areas of eastern Japan affected by the incident, it is crucial to gain the greatest possible understanding of the nature of this contamination in order to inform the most appropriate clean-up response.

Temporal changes in radiocesium deposition in various forest stands following the Fukushima Dai-ichi Nuclear Power Plant accident.

Science.gov (United States)

Kato, Hiroaki; Onda, Yuichi; Hisadome, Keigo; Loffredo, Nicolas; Kawamori, Ayumi

2017-01-01

In this study, we investigated the transfer of canopy-intercepted radiocesium to the forest floor following the Fukushima Dai-ichi Nuclear Power Plant accident. The 137 Cs content of throughfall, stemflow, and litterfall were monitored in two coniferous stands (plantations of Japanese cedar) and a deciduous mixed broad-leaved forest stand (oak with red pine) from July 2011 to December 2012. The forest floor of cedar stands had received higher levels of additional 137 Cs deposition compared with the mixed broad-leaved stand during the sampling period. The cumulative 137 Cs deposition during the study period was 119 kBq m -2 for the mature cedar stand, 105 kBq m -2 for the young cedar stand, and 41.5 kBq m -2 for the broad-leaved stand. The deposition of 137 Cs to the forest floor occurred mainly in throughfall during the first rainy season, from July to September 2011 (<200 d after the initial fallout); thereafter, the transfer of 137 Cs from the canopy to forest floor occurred mainly through litterfall. A double exponential field-loss model, which was used to simulate the removal of 137 Cs from canopies, was the best fit for the temporal changes in the canopy 137 Cs inventory. Copyright © 2015 Elsevier Ltd. All rights reserved.

Removal of Radiocesium from Food by Processing: Data Collected after the Fukushima Daiichi Nuclear Power Plant Accident - 13167

Energy Technology Data Exchange (ETDEWEB)

Uchida, Shigeo; Tagami, Keiko [Office of Biospheric Assessment for Waste Disposal, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage-ku, Chiba 263-8555 (Japan)

2013-07-01

Removal of radiocesium from food by processing is of great concern following the accident of TEPCO's Fukushima Daiichi Nuclear Power Plant accident. Foods in markets are monitored and recent monitoring results have shown that almost all food materials were under the standard limit concentration levels for radiocesium (Cs-134+137), that is, 100 Bq kg{sup -1} in raw foods, 50 Bq kg{sup -1} in baby foods, and 10 Bq kg{sup -1} in drinking water; those food materials above the limit cannot be sold. However, one of the most frequently asked questions from the public is how much radiocesium in food would be removed by processing. Hence, information about radioactivity removal by processing of food crops native to Japan is actively sought by consumers. In this study, the food processing retention factor, F{sub r}, which is expressed as total activity in processed food divided by total activity in raw food, is reported for various types of corps. For white rice at a typical polishing yield of 90-92% from brown rice, the F{sub r} value range was 0.42-0.47. For leafy vegetable (indirect contamination), the average F{sub r} values were 0.92 (range: 0.27-1.2) after washing and 0.55 (range: 0.22-0.93) after washing and boiling. The data for some fruits are also reported. (authors)

Through wall degradation problem of the turbine extraction steam drain piping due to liquid drop impingement and measures taken for this problem at Fukushima Dai-ichi Nuclear Power Plant Unit 6

International Nuclear Information System (INIS)

Inagaki, Takeyuki; Kobayashi, Teruaki; Shimada, Shigeru; Inoue, Ryousuke; Usuba, Satoshi; Kimura, Takeo

2011-01-01

Through wall degradation was found on the extraction steam drain piping of Unit 6 of Fukushima Dai-ichi Nuclear Power Plant owned by Tokyo Electric Power Company after replacement of the turbine rotors with those of higher thermal efficiency. The mechanism of this degradation was loss of material due to liquid drop impingement. Since the estimated life time of the piping based on wall thickness measurements before the replacement was at least 9 years, the rapid wall thinning occurred after the replacement. This paper describes a summary of the phenomenon, its degradation mechanism and root cause, a temporary measurement taken for an immediate action and permanent measures taken during the next refueling outage. (author)

Spatio-temporal variability of the deposited radioactive materials in forest environments after the Fukushima Daiichi NPP accident

Science.gov (United States)

Kato, H.; Onda, Y.; Komatsu, Y.; Yoda, H.

2012-12-01

Soil, vegetation and other ecological compartments are expected to be highly contaminated by the deposited radionuclides after the Fukushima Daiichi nuclear power plant (NPP) accident triggered by a magnitude 9.1 earthquake and the resulting tsunami on Marchi 11, 2011. Study site have been established in Yamakiya district, Kawamata Town, Fukushima prefecture, located about 35 km from Fukushima power plant, and designated as the evacuated zone. The total deposition of radioactive materials at the study site ranged from 0.02to >10 M Bq/m2 for Cs-137. The mature cedar, young cedar, and broad-leaf stands were selected as experimental site for the monitoring of spatio-temporal variability of the deposited radionuclides after the accidental release of radioactive materials. In order to measure the vertical distribution of radioactivity in forest, a tower with the same height of tree have been established at each experimental site. The measurement of radioactivity by using a portable Ge gamma-ray detector (Detective-DX-100, Ortec) and radionuclide analysis of leaf samples at different height revealed that a large proportion of radionuclides which deposited on forest were trapped by canopies of the cedar forests. In contrast, in the broad-leaf forest highest radioactivity was found at the forest floor. Furthermore, spatio-temporal variability of radioactivity at the forest floor indicated that huge amount of caesium still remains on the canopy of coniferous forest, and subsequently transfers to forest floor in association with throughfall, stemflow, and litter fall.

New Standards in Liquid Waste Treatment at Fukushima Dai-ichi - 13134

Energy Technology Data Exchange (ETDEWEB)

Sylvester, Paul; Milner, Tim; Ruffing, Jennifer; Poole, Scott [EnergySolutions, 100 Center Point Circle, Suite 100, Center Point II, Columbia, SC 29210 (United States); Townson, Paul; Jensen, Jesse [EnergySolutions, 2345 Stevens Drive, Suite 240, Richland, WA 99354 (United States)

2013-07-01

The earthquake and tsunami on March 11, 2011 severely damaged the Fukushima Dai-ichi nuclear plant leading to the most severe nuclear incident since Chernobyl. Ongoing operations to cool the damaged reactors at the site have led to the generation of highly radioactive coolant water. This is currently mainly treated to remove Cs-137 and Cs-134 and passed through a reverse osmosis (RO) unit to reduce the salinity before being cycled back to the reactors. Because only the Cs isotopes are removed, the RO reject water still contains many radioactive isotopes and this has led to the accumulation of over 200,000 cubic meters (52 million gallons) of extremely contaminated water which is currently stored on site in tanks. EnergySolutions, in partnership with Toshiba, were contracted to develop a system to reduce 62 isotopes in this waste down to allowable levels. This was a significant technical challenge given the high background salt content of the wastewater, the variation in aqueous chemistry of the radioactive isotopes and the presence of non-active competing ions (e.g. Ca and Mg) which inhibit the removal of isotopes such as Sr-89 and Sr-90. Extensive testing was performed to design a suitable system that could meet the required decontamination goals. These tests were performed over a 6 month period at facilities available in the nearby Fukushima Dai-ni laboratory using actual waste samples. This data was then utilized to design a Multi Radioactive Nuclides Removal System (MRRS) for Fukushima which is a modified version of EnergySolutions' proprietary Advanced Liquid Processing System (ALPS)'. The stored tank waste is fed into a preliminary precipitation system where iron flocculation is performed to remove a number of isotopes, including Sb-125, Ru-106, Mn-54 and Co-60. The supernatant is then fed into a second precipitation tank where the pH is adjusted and the bulk of the Mg, Ca and Sr precipitated out as carbonates and hydroxides. After passing through a

Radioactive Cs in the estuary sediments near Fukushima Daiichi Nuclear Power Plant

International Nuclear Information System (INIS)

Yamasaki, Shinya; Imoto, Junpei; Furuki, Genki; Ochiai, Asumi; Ohnuki, Toshihiko; Sueki, Keisuke; Nanba, Kenji; Ewing, Rodney C.; Utsunomiya, Satoshi

2016-01-01

The migration and dispersion of radioactive Cs (mainly "1"3"4Cs and "1"3"7Cs) are of critical concern in the area surrounding the Fukushima Daiichi Nuclear Power Plant (FDNPP). Considerable uncertainty remains in understanding the properties and dynamics of radioactive Cs transport by surface water, particularly during rainfall-induced flood events to the ocean. Physical and chemical properties of unique estuary sediments, collected from the Kuma River, 4.0 km south of the FDNPP, were quantified in this study. These were deposited after storm events and now occur as dried platy sediments on beach sand. The platy sediments exhibit median particle sizes ranging from 28 to 32 μm. There is increasing radioactivity towards the bottom of the layers deposited; approximately 28 and 38 Bq g"−"1 in the upper and lower layers, respectively. The difference in the radioactivity is attributed to a larger number of particles associated with radioactive Cs in the lower part of the section, suggesting that radioactive Cs in the suspended soils transported by surface water has decreased over time. Sequential chemical extractions showed that ~ 90% of "1"3"7Cs was strongly bound to the residual fraction in the estuary samples, whereas 60 ~ 80% of "1"3"7Cs was bound to clays in the six paddy soils. This high concentration in the residual fraction facilitates ease of transport of clay and silt size particles through the river system. Estuary sediments consist of particles < 100 μm. Radioactive Cs desorption experiments using the estuary samples in artificial seawater revealed that 3.4 ± 0.6% of "1"3"7Cs was desorbed within 8 h. More than 96% of "1"3"7Cs remained strongly bound to clays. Hence, particle size is a key factor that determines the travel time and distance during the dispersion of "1"3"7Cs in the ocean. - Highlights: • Cs-137 of estuary sediment impacted by the FDNPP was measured. • Physical and chemical properties were measured also. • Increasing radioactivity was

Radioactive Cs in the estuary sediments near Fukushima Daiichi Nuclear Power Plant

Energy Technology Data Exchange (ETDEWEB)

Yamasaki, Shinya, E-mail: s-yamasaki@ied.tsukuba.ac.jp [Faculty of Pure and Applied Sciences and Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Imoto, Junpei; Furuki, Genki; Ochiai, Asumi [Department of Chemistry, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan); Ohnuki, Toshihiko [Advanced Science Research Center, Japan Atomic Energy Agency, Shirakata Shirane 2-4, Tokai, Ibaraki 319-1195 (Japan); Sueki, Keisuke [Faculty of Pure and Applied Sciences and Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Nanba, Kenji [Department of Environmental Management, Faculty of Symbiotic System Science, Fukushima University, Kanayagawa 1, Fukushima, 960-1296 (Japan); Ewing, Rodney C. [Department of Geological Sciences and Center for International Security and Cooperation, Stanford University, Stanford, CA 94305-2115 (United States); Utsunomiya, Satoshi [Department of Chemistry, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan)

2016-05-01

The migration and dispersion of radioactive Cs (mainly {sup 134}Cs and {sup 137}Cs) are of critical concern in the area surrounding the Fukushima Daiichi Nuclear Power Plant (FDNPP). Considerable uncertainty remains in understanding the properties and dynamics of radioactive Cs transport by surface water, particularly during rainfall-induced flood events to the ocean. Physical and chemical properties of unique estuary sediments, collected from the Kuma River, 4.0 km south of the FDNPP, were quantified in this study. These were deposited after storm events and now occur as dried platy sediments on beach sand. The platy sediments exhibit median particle sizes ranging from 28 to 32 μm. There is increasing radioactivity towards the bottom of the layers deposited; approximately 28 and 38 Bq g{sup −1} in the upper and lower layers, respectively. The difference in the radioactivity is attributed to a larger number of particles associated with radioactive Cs in the lower part of the section, suggesting that radioactive Cs in the suspended soils transported by surface water has decreased over time. Sequential chemical extractions showed that ~ 90% of {sup 137}Cs was strongly bound to the residual fraction in the estuary samples, whereas 60 ~ 80% of {sup 137}Cs was bound to clays in the six paddy soils. This high concentration in the residual fraction facilitates ease of transport of clay and silt size particles through the river system. Estuary sediments consist of particles < 100 μm. Radioactive Cs desorption experiments using the estuary samples in artificial seawater revealed that 3.4 ± 0.6% of {sup 137}Cs was desorbed within 8 h. More than 96% of {sup 137}Cs remained strongly bound to clays. Hence, particle size is a key factor that determines the travel time and distance during the dispersion of {sup 137}Cs in the ocean. - Highlights: • Cs-137 of estuary sediment impacted by the FDNPP was measured. • Physical and chemical properties were measured also. �

Tracking Radioactive Fallout from the Fukushima Dai-ichi Accident in Arctic Snow

Science.gov (United States)

Osterberg, E. C.; Thompson, J.; Landis, J.; Albert, M. R.; Campbell, S. W.; Hawley, R. L.; Virginia, R. A.

2011-12-01

The March 11, 2011 magnitude 9.0 Tohoku, Japan earthquake produced a tsunami that inundated the Fukushima Dai-ichi nuclear power plant and led to the accidental release of radioactive 131I, 132Te, 134Cs, and 137Cs to the atmosphere. The Japanese Nuclear Safety Commission estimates that 12,000 TBq of 137Cs were released to the atmosphere during the incident, which represents ~14% of the total estimated 137Cs emission from the Chernobyl disaster in April 1986. Measurements of airborne radiation collected at the Fukushima plant illustrate that >50% of the total emitted radiation was released on March 15 and 16 associated with explosions and fires at reactor units 1, 2, and 4, and 70% was emitted in the first 5 days of the event. The source of the radiation is thus well constrained in time and space, providing an opportunity to better understand long-range atmospheric transport processes from Asia to the Arctic, while also assessing the magnitude of the fallout in the Arctic. Here we describe the 137Cs and 134Cs fallout flux near Thule, Greenland (1700 m a.s.l.), at Summit (3200 m a.s.l.), Greenland, and within Denali National Park, Alaska (2400-3900 m a.s.l.) based on series of large-volume (5-15 l) snow pit samples collected in June and July, 2011. In addition to assessing the spatial variability of Fukushima fallout in the Arctic, the elevation range of samples allows for an analysis of any vertical heterogeneity in fallout transport and deposition. Major ion concentrations and stable water isotope ratios are used to confirm the seasonal timing of the Fukushima fallout horizon in the snowpack. Radiocesium was concentrated and isolated from the snow pit meltwater using the well-established ammonium phosphomolybdate (AMP) adsorption method, and 134Cs and 137Cs concentrations were measured using gamma spectrometry with a Canberra 3523 well-type intrinsic Ge-detector at the Dartmouth College Short-Lived Isotope Laboratory. NOAA HYPLIT atmospheric forward

TEPCO's risk communication activities in Fukushima Prefecture in light of the lessons learned from the Fukushima Daiichi Nuclear Power Station accident

International Nuclear Information System (INIS)

Sagasaki, Yoshitoyo; Yamamoto, Takashi

2015-01-01

This paper introduces the risk communication activities of the Tokyo Electric Power Company (TEPCO) in Fukushima Prefecture. It analyzed the organizational cause as the background for the Fukushima Daiichi Nuclear Power Station Accident, and concluded that the root cause of the accident is the thought that 'safety has already been secured, and operation rate and the like are important management issues, which incurred the insufficient preparedness for accident.' It has taken six measures as nuclear safety reform plans. One of these is the 'enhancement of risk communication activities.' The nuclear power leader take the initiative to disclose risk under the idea that 'there is no absolute safety (zero risk) in nuclear power,' and promote risk communication for continuously obtaining the understanding of the regional community and society about safety measures, etc. To implement risk communication, 'risk communicators' are installed, and they propose for the management and nuclear leader, about the risk perception and measures associated with public disclosure and its limit, and perform risk communication in accordance with the policy. As the examples of these initiatives, this paper introduces the cases of Fukushima Prefecture, questionnaire study, and evaluations by international organizations. (A.O.)

Radioactivity in vegetation at the Fukushima area. A study on contamination by radionuclides released from TEPCO's Fukushima Daiichi nuclear power plants

International Nuclear Information System (INIS)

Momoshima, Noriyuki; Sugihara, Sinji; Ozawa, Ryosuke; Nakama, Akimitsu; Ichikawa, Ryohei; Maekawa, Akihiro

2013-01-01

Leaves of Kudzu collected from the Fukushima Daiichi NPP accident contamination area are shown to exhibit high levels of "1"3"4Cs and "1"3"7Cs activity. Radioactive dusts that attached to the leaf surface were measured at significant levels (as confirmed by IP) for a sample collected in 2011, but at lower levels for samples collected in 2012. This suggests that root uptake would be considered a major source of internal contamination prior to collection of the 2012 samples. The surface and internal contamination was evaluated for two leaves of the 2011 sample and the radiocesium attached contributed to 13% and 63% of the total activity, respectively. The "1"3"4"+"1"3"7Cs activity of the 2012 samples showed a positive correlation with the radiation dose rate measured at the sampling points; however, the "1"3"4"+"1"3"7Cs activity estimated as an internal fraction still seemed high when compared to that of the 2011 sample. These results suggest that the surface absorption of radiocesium from attached dusts is likely responsible for the observed high internal activity. (author)

Applicability of AWJ technique for dismantling reactor of the Fukushima Daiichi Nuclear Power Station. Cutting test of imitation of fuel debris and optimization of the cutting condition

International Nuclear Information System (INIS)

Maruyama, Shin-ichiro; Watatani, Satoshi

2016-01-01

Based on findings during recovery works that followed the accident at Three Mile Island Station 2, it is assumed that the reactor internals at the Fukushima Daiichi Nuclear Power Station (1F) have complex geometries intermixed with melted fuel and confined in limited spaces. Accordingly, abrasive water jet (AWJ) cutting method is considered to be a promising technique that can be safely and reasonably used for cutting and removing reactor internals. The authors conducted tests to examine the possibility of application and to solve the problems of this technique. In the tests imitation of fuel debris and optimization of the cutting condition is used. The test result made the measures for some of the associated issues clear, and demonstrated that AWJ cutting method is assumed as one of the promising techniques for removing reactor internals. (author)

Fuel debris characterization and treatment technologies development for TEPCO's Fukushima Daiichi Nuclear Power Station. 2012 annual research and development report

International Nuclear Information System (INIS)

2014-03-01

Since March 11, 2011, severe accidents occurred at Fukushima Daiichi Nuclear Power Station (1F NPS), the Government of Japan and Tokyo Electric Power Company (TEPCO) and all Japan's companies have been worked on the remediation. The first meeting of 'Government and TEPCO's Mid-to-Long Term Countermeasure Meeting' was held on December 16, 2011, and then' the Council for the Decommissioning of TEPCO's Fukushima Daiichi Nuclear Power Station' was established on February 8, 2013, and 19 research and development projects and Working team / Sub working team were launched. Japan Atomic Energy Agency (JAEA); Fukushima Project Teams in Nuclear Fuel Cycle Laboratories and Nuclear Science Research Institute are belonging to the projects of 'Fuel debris characterization (2-(3)-1)', 'Analysis of fuel debris (2-(3)-2)' and 'Treatment technology development of fuel debris (2-(3)-3)'. In the 2012 JFY, we carried out research and development on the 'Fuel debris characterization (2-(3)-1)' and 'Treatment technology development of fuel debris (2-(3)-3)', and obtained some results on the debris properties and debris treatment technologies. This document report annual research and development results of above two projects in 2012 JFY. In the Project of 'Fuel debris characterization (2-(3)-1)', the debris chemical form, phase state and composition were estimated by thermodynamic calculation with referring sever accident code results and the fuel debris properties which needed for developing the methods/devices for defueling was identified with information of Three Mile Island and sever accident study. As for investigation of reaction and products specific to 1F accident, fundamental data on the debris such as mechanical properties i.e. hardness, and effects of sea water, B 4 C, ratio of Zr content and O/M, and thermal properties as melting points, thermal conductivity, etc. were obtained by

Measuring Radioactivity from Fukushima Daiichi in New Mexico

International Nuclear Information System (INIS)

McNaughton, Michael

2011-01-01

On March 11, 2011, the Fukushima Daiichi nuclear power plant was damaged by the tsunami that followed the 'Great East Japan Earthquake,' and the reactor subsequently leaked radioactive material. In response, LANL augmented the routine ambient (AIRNET) and stack (Rad-NESHAP) measurements with three high-volume samplers: No.167 at the Old White Rock Fire Station; No.173 at the TA-49 gate, and No.211 at the Los Alamos Medical Center. Previous accidents, such as the Three-Mile-Island accident in 1979 and the Chernobyl accident in 1986, indicated that the most likely releases were (a) the noble gases: krypton and xenon; and (b) the volatile elements: cesium, tellurium, and iodine. At the latitude of Fukushima, the predominant winds across the Pacific Ocean are from west to east, and models predicted that the plume would arrive in the western US on about March 18. By this time the shorter-lived isotopes would have decayed. Therefore, the expected radionuclides were xenon-133, cesium-134, cesium-136, cesium-137, tellurium-132, iodine-131, and iodine-132. As expected, cesium-134, cesium-136, cesium-137, tellurium-132, iodine-131, and iodine-132 were all detected by all three high-volume samplers during March 17-21. The concentrations peaked during the March 24-28 period. After this, concentrations of all nuclides declined. In general, the concentrations were consistent with those measured by the EPA RadNet system and many other monitoring systems throughout the world. At the time of writing, preliminary results from the AIRNET and Rad-NESHAP systems are being reported. More detailed results are described in LA-UR-11-10304 and will be reported in full in the annual environmental report for 2011. All previous releases from nuclear reactors have been dominated by noble gases, primarily krypton and xenon, which are not measured by the high-volume samplers or the AIRNET system. However, in sufficient concentrations these and other fission products would be detected by NEWNET

Enhancement of organizational resilience in light of the Fukushima Dai-ichi Nuclear Power Plant accident (4). Consideration of nurturing attitude to achieve the safety-II

International Nuclear Information System (INIS)

Oba, Kyoko; Yoshizawa, Atsufumi; Kitamura, Masaharu

2015-01-01

The Fukushima nuclear plant accident has been examined aiming at clarifying the factors influencing responding which is one of the four cornerstones of resilience engineering. Among the causal factors of responding, such as attitude, skill, health and environment, particular attention has been paid on the role of attitude. In addition, the case of Tokai Dai-ni nuclear plant, which was the success case despite tsunami attack, and the case of Fukushima Dai-ichi nuclear plant have been examined focusing on preparatory actions taken prior to the tsunami attack. Through the comparative examinations, attitudes of several kinds have been identified as key factors contributing to enhance organizational resilience. Moreover, the importance of safety-II concept proposed in conjunction with the methodology of resilience engineering has been clearly exemplified. As a whole, it can be concluded that the methodology of resilience engineering and the concept of safety-II are quite effective when utilized with the structured model. (author)

Cs-134 and Cs-137 radioactivity in river waters in Fukushima, Miyagi, Ibaraki and Gunma Prefectures in August 2012 after the Fukuhsima Daiichi Nuclear Power Plant accident

Energy Technology Data Exchange (ETDEWEB)

Nagao, S.; Ochiai, S.; Yamamoto, M. [Low Level Radioactivity Laboratory, Institute of Nature and Environmental Technology, Kanazawa University, Wake, Nomi, Ishikawa 923-1224(Japan); Kanamori, M. [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 921-1192 (Japan); Tomihara, S. [Environmental Aquarium Aquamarine Fukushima, 50 Tatsumi, Onahama, Iwaki, Fukushima 971-8101(Japan); Suzuki, K. [Gunma Prefectural Fisheries Experimental Station, 13 Shikishima, Maebashi, Gunma 371-1036 (Japan)

2014-07-01

About 15 PBq from both {sup 134}Cs and {sup 137}Cs were released from the Fukushima Dai-ichi Nuclear Power Plant (NPP) because of venting operations and hydrogen explosions. The Ministry of Education, Culture, Sports, Science and Technology of Japan reported total surface deposition of {sup 134}Cs and {sup 137}Cs in Japan. To estimate short-term and long-term impacts of the radiation dose in Japan, it is important to understand the dynamics of radionuclides, especially those of {sup 134}Cs and {sup 137}Cs, on river watershed environments. This study investigated {sup 134}Cs and {sup 137}Cs radioactivity in river systems in Fukushima, Miyagi, Ibaraki and Gunma prefectures, Japan. The secondary radioactive dispersion of radiocesium from the contaminated watershed to the river waters is reported for research areas with widely various radiocesium deposition on ground surfaces at 18 months after the accident. Field experiments were conducted at a fixed station in four rivers (the Uta, Niida, Natsui, and Same Rivers) in Fukushima Prefecture, and the Kuji River, and Naka River in Ibaraki Prefecture in August 2012. The Abukuma River was set up one site at the upper, two sites in the middle reach in Fukushima Prefecture and at one site in the lower area in Miyagi Prefecture. The Tone River system has three stations at the upper river area in Gunma Prefecture and one site at the lower reach in Ibaraki Prefecture. Surface deposition results reveals significant external radioactivity in a zone extending northwest from the NPP. However, a mountainous area in Gunma Prefecture, located about 220 km from Fukushima Dai-ichi NPP south of Fukushima Prefecture, shows similar accumulation of {sup 134}Cs and {sup 137}Cs. The 20 L of surface river waters were collected at the station using buckets. The radioactivity of {sup 134}Cs and {sup 137}Cs in the river waters was measured with gamma-ray spectrometry using ammonium molybdophosphate (AMP)/Cs compound method with a low background Ge

Initial and present situation of food contamination in Japan after the accident at the Fukushima Dai-Ichi Nuclear Power Plant

International Nuclear Information System (INIS)

Aono, Tatsuo; Yoshida, Satoshi; Akashi, Makoto

2016-01-01

The accident at the Fukushima Dai-ichi Nuclear Power Plant (NPP) in March 2011 affected not only the terrestrial environment of Fukushima prefecture and the surrounding area, but also the marine area facing the NPP. Our present study is focused on the concentrations of radionuclides in agricultural products of Fukushima and sea-foods collected off Fukushima after the accident. The regulation value for radiocesium in vegetables, meat and fish was revised from 500 Bq/kg-wet to 100 Bq/kg-wet on 1 April 2012. The overall activity of radiocesium in these products was found to be within the limit of tolerance in respect to Japanese and also international regulations, but there is still radiocesium found at activities greater than this level in edible wild plants, wild mushrooms and game such as boar meat. Although the activities of radionuclides exceeding the regulatory limits were not detected in marine products collected off Fukushima after April 2015, the commercial marine fishery has not received approval in the affected areas except for certain species. We learned from the Fukushima accident that long-term kinetic studies of radionuclides in terrestrial and marine environments is extremely important for prevention of internal contamination, since contamination with radionuclides occurs via the food chain in the environment. (authors)

Concentration levels of cesium-137 in soils of the municipalities of Guadalupe and Zacatecas before the accident of Fukushima Daiichi; Niveles de concentracion de cesio-137 en suelos de los municipios de Guadalupe y Zacatecas antes del accidente de Fukushima Daiichi

Energy Technology Data Exchange (ETDEWEB)

Mireles, F.; Davila, J. I.; Pinedo, J. L.; Lopez, H.; Rios, C.; Saucedo, S. A.; Flores, F. E., E-mail: fmireles@uaz.edu.mx [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (MX)

2011-11-15

The study of the emitter radioisotopes of gamma-rays in soil is very important considering damages to the health and quality of the environment. The main objective of this work is the study of the concentration of the artificial radioisotope {sup 137}Cs in soil of the cities and municipalities of Zacatecas and Guadalupe of the Zacatecas State, Mexico. The study was carried out in two stages for different times, the first stage corresponded to the cities of Zacatecas and Guadalupe in 2000; and the second corresponded to the municipalities of Zacatecas and Guadalupe in 2008. The first study region was the cities of Zacatecas and Guadalupe, and environs where 20 soil samples were obtained. The second study region was inside the municipalities of Guadalupe and Zacatecas and 44 samples of near soil to the communities with major population in both municipalities were obtained. A spectrometry system of gamma-rays was used based on a coaxial detector of germanium hyper pure of high resolution, and was calculated the concentration of the {sup 137}Cs with the energy photo-pick 661.66 KeV. In this work the activity concentrations of the {sup 137}Cs in soil are presented and their variation in function of the time. These data will be a reference to evaluate a possible increment of the {sup 137}Cs because of the accident of Fukushima Daiichi (Japan) nuclear power plant happened March 11, 2011. (Author)

The total release of xenon-133 from the Fukushima Dai-ichi nuclear power plant accident

International Nuclear Information System (INIS)

Stohl, Andreas; Seibert, Petra; Wotawa, Gerhard

2012-01-01

The accident at the Fukushima Dai-ichi nuclear power plant (FD-NPP) on 11 March 2011 released large amounts of radioactivity into the atmosphere. We determine the total emission of the noble gas xenon-133 ( 133 Xe) using global atmospheric concentration measurements. For estimating the emissions, we used three different methods: (i) using a purely observation-based multi-box model, (ii) comparisons of dispersion model results driven with GFS meteorological data with the observation data, and (iii) such comparisons with the dispersion model driven by ECMWF data. From these three methods, we have obtained total 133 Xe releases from FD-NPP of (i) 16.7 ± 1.9 EBq, (ii) 14.2 ± 0.8 EBq, and (iii) 19.0 ± 3.4 EBq, respectively. These values are substantially larger than the entire 133 Xe inventory of FD-NPP of about 12.2 EBq derived from calculations of nuclear fuel burn-up. Complete release of the entire 133 Xe inventory of FD-NPP and additional release of 133 Xe due to the decay of iodine-133 ( 133 I), which can add another 2 EBq to the 133 Xe FD-NPP inventory, is required to explain the atmospheric observations. Two of our three methods indicate even higher emissions, but this may not be a robust finding given the differences between our estimates. - Highlights: ► We determine the total release of xenon-133 from the Fukushima nuclear accident. ► We used global measurements and a box model, as well as dispersion model estimates. ► Total 133 Xe release is about 14.2-19 EBq, more than Fukushima 133 Xe inventory. ► Additional release of iodine-133 and decay into 133 Xe needed to explain results.

Safety-critical human factors issues derived from analysis of the TEPCO Fukushima Daiichi accident investigation reports

International Nuclear Information System (INIS)

Sakuda, Hiroshi; Takeuchi, Michiru

2013-01-01

The Fukushima Daiichi nuclear power plant accident on March 11, 2011 had a large impact both in and outside Japan, and is not yet concluded. After Tokyo Electric Power Co.'s (TEPCO's) Fukushima accident, electric power suppliers have taken measures to respond in the event that the same state of emergency occurs - deploying mobile generators, temporary pumps and hoses, and training employees in the use of this equipment. However, it is not only the “hard” problems including the design of equipment, but the “soft” problems such as organization and safety culture that have been highlighted as key contributors in this accident. Although a number of organizations have undertaken factor analysis of the accident and proposed issues to be reviewed and measures to be taken, a systematic overview about electric power suppliers' organization and safety culture has not yet been undertaken. This study is based on three major reports: the report by the national Diet of Japan Fukushima Nuclear Accident Independent Investigation Commission (the Diet report), the report by the Investigation Committee on the Accident at Fukushima Nuclear Power Stations of Tokyo Electric Power Company (Government report), and the report by the non-government committee supported by the Rebuild Japan Initiative Foundation (Non-government report). From these reports, the sections relevant to electric power suppliers' organization and safety culture were extracted. These sections were arranged to correspond with the prerequisites for the ideal organization, and 30 issues to be reviewed by electric power suppliers were extracted using brainstorming methods. It is expected that the identified issues will become a reference for every organization concerned to work on preventive measures hereafter. (author)

Tracing cohesive sediment transportation at river mouths around Tokyo, Japan by Cesium originated from Fukushima Daiichi Power Plant

Science.gov (United States)

koibuchi, Y.

2012-12-01

Sediment transport at river mouths, which consists of suspended-load and bed-load, has not been fully understood, since bed-load transport of cohesive sand is difficult to observe. Especially, the impact of sediment transport on the total amount of fine-grained cohesive sediment has not been elucidated. Cesium-134 and cesium-137 were spread from the Fukushima Daiichi Nuclear Power Plant (FDNPP) after the earthquake of March 11 of 2011, and attached to the fine-grained sand on the land. The contaminated sand flowed into the river mouths through the rivers possibly due to the complex physical processes in estuarine areas. To evaluate the fine-grained sediment transport around Tokyo and Tokyo Bay, field observations were carried out utilizing radionuclide originated from FDNPP as an effective tracer. The cohesive sediment transport at three different river mouths around Tokyo was successfully quantified. The cohesive sediment transport deposited in the estuary was found to be greatly dependent on the land use, geometry, river discharge and salinity. In addition,the transport driven by the rainfall was minute, and its behavior was quite different from suspended solids. Although further field observations of radionuclide are necessary, it is clear that fine-grained sediment in the bay from rivers already settled on the river mouth by aggregation. The settled sand will not move even in rainfall events. Consequently, the transport of radionuclide to the Pacific Ocean may not occur.; Cesium distribution around Tokyo Bay ; Cesium Concentration in Edogawa river

Factors associated with nurses' intention to leave their jobs after the Fukushima Daiichi Nuclear Power plant accident.

Directory of Open Access Journals (Sweden)

Yoshinobu Sato

Full Text Available We conducted a survey among nurses who were working at the Fukushima Medical University Hospital at the time of the Fukushima Daiichi Nuclear Power Plant accident to clarify the factors associated with their intention to leave their jobs during the radiation emergency. We asked 345 nurses (17 men and 328 women about their intention to leave their jobs after the accident. We also asked about relevant factors including the participants' demographic factors, living situation, working status, and knowledge of radiation health effects. We found that living with preschoolers (OR = 1.87, 95%CI: 1.02-3.44, p = 0.042, anxiety about life in Fukushima City after the accident (OR = 5.55, 95%CI: 1.18-26.13, p = 0.030, consideration of evacuation from Fukushima after the accident (OR = 2.42, 95%CI: 1.45-4.06, p = 0.001, consideration of the possible radiation health effects in children (OR = 1.90, 95%CI: 1.02-3.44, p = 0.042, and anxiety about relationships with colleagues in the hospital after the accident (OR = 3.23, p = 0.001 were independently associated with the nurses' intention to leave their jobs after the accident. On the other hand, the percentage of nurses with knowledge on radiation health effects was relatively low among those who had the intention to leave the job and among those who did not have the intention to leave the job after the accident, with no significant differences between the two groups. Our results suggest the need for an education program for nurses regarding radiation health effects.

Regulatory risks associated with nuclear safety legislation after Fukushima Daiichi Nuclear Accident in Japan. Focus on legal structure of the nuclear reactor regulation act

International Nuclear Information System (INIS)

Tanabe, Tomoyuki; Maruyama, Masahiro

2016-01-01

Nuclear safety regulations enforced after Fukushima Daiichi Nuclear Accident under the Nuclear Reactor Regulation Act face the following regulatory problems that involve potential risk factors for nuclear businesses; 1) 'entity based regulation' unable to cope with business cessation or bankruptcy of the entity subject of regulation, 2) potential risk of the Nuclear Regulation Authority's inappropriate involvement in nuclear industry policy beyond their duty, and 3) compliance of backfits under vague regulations. In order to alleviate them, this report, through analyzing these regulatory problems from the view point of sound development of the nuclear industry, proposes the following regulatory reforms; (1) To clarify the rule for industry policy in nuclear regulations and enable the authority, Ministry of Economy, Trade and Industry, to choose most appropriate industrial policy measure. (2) Through establishing safety goals as measures to promote continuous improvement of nuclear safety regulations, to stimulate timely adjustments of the regulations, and to introduce a legal mechanism into the nuclear regulation systems under which validity of administrative law and its application can be checked. (author)

Synthesis of the available information about the radioactive contamination of the Japanese terrestrial environment caused by the Fukushima Dai-ichi accident - July 13, 2011

International Nuclear Information System (INIS)

2011-01-01

The French institute of radiation protection and nuclear safety (IRSN) collects and analyses regularly the published data concerning the contamination of the Japanese terrestrial environment caused by the Fukushima Dai-ichi power plant accident. This synthesis presents a status of the data recently obtained since the previous similar notes of April 12 and May 25. The note presents the detailed activity analysis of several surface soil samples (Iitate Maeda, Namie, Hirono, Fukushima..), a mapping of 137 Cs and 134 Cs cumulated deposits in a 80 km area around the damaged power plant, the evolution of radioactive deposits since March 2011 in different places (Fukushima, Hitachinaka, Saitama, Utsunomiya), the evolution of the 134 Cs+ 137 Cs and 131 I contamination of agriculture food products and of drinking water. The IRSN has detected also a significant contamination of some tea samples imported from the Omaezaki region and intercepted by the French customs. Some information about tea and bamboo shoots cultivation and processing in Japan is added in appendix. (J.S.)

Determinants of the return to hometowns after the accident at Fukushima Dai-ichi nuclear power plant: A case study for the village of Kawauchi

International Nuclear Information System (INIS)

Orita, M.; Hayashida, N.; Urata, H.; Shinkawa, T.; Endo, Y.; Takamura, N.

2013-01-01

The Great East Japan Earthquake in March 2011 destroyed the Fukushima Dai-ichi Nuclear Power Plant (FNPP) and almost all residents in a 20 km radius from the plant eventually evacuated. FNPP reactors were stabilised in December 2011; some evacuees decided to return to their hometowns, and the other evacuees remained. Efforts were made to identify the determinants that affect the decision to return home in order to promote recovery of the surrounding area of FNPP. Seventy one residents who had not returned to hometown and 56 residents who had returned were selected. Logistic regression analysis adjusted for confounding factors showed that being female [odds ratio (OR): 2.43, p=50.03], living in areas with relatively higher ambient doses (OR: 3.60, p=50.01) and expressing anxiety over radiation exposure (OR: 8.91, p < 0.01) were independently associated with decisions not to return. Results of this study suggest the importance of active participation by scientists and local authorities in communicating the risk to the general population involved in returning home. (authors)

Radioactive Cs in the Severely Contaminated Soils Near the Fukushima Daiichi Nuclear Power Plant

Energy Technology Data Exchange (ETDEWEB)

Kaneko, Makoto; Iwata, Hajime; Shiotsu, Hiroyuki; Masaki, Shota; Kawamoto, Yuji; Yamasaki, Shinya; Nakamatsu, Yuki; Imoto, Junpei; Furuki, Genki; Ochiai, Asumi [Department of Chemistry, Kyushu University, Fukuoka (Japan); Nanba, Kenji [Department of Environmental Management, Faculty of Symbiotic System Science, Fukushima University, Fukushima (Japan); Ohnuki, Toshihiko [Advanced Science Research Center Japan Atomic Energy Agency, Tokai (Japan); Ewing, Rodney C. [Department of Geological Sciences, Center for International Security and Cooperation, Stanford University, Stanford, CA (United States); Utsunomiya, Satoshi, E-mail: utsunomiya.satoshi.998@m.kyushu-u.ac.jp [Department of Chemistry, Kyushu University, Fukuoka (Japan)

2015-09-01

Radioactive Cs isotopes ({sup 137}Cs, t{sub 1/2} = 30.07 years and {sup 134}Cs, t{sub 1/2} = 2.062 years) occur in severely contaminated soils within a few kilometer of the Fukushima Daiichi nuclear power plant at concentrations that range from 4 × 10{sup 5} to 5 × 10{sup 7} Bq/kg. In order to understand the mobility of Cs in these soils, both bulk and submicron-sized particles elutriated from four surface soils have been investigated using a variety of analytical techniques, including powder X-ray diffraction analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and analysis of the amount of radioactivity in sequential chemical extractions. Major minerals in bulk soil samples were quartz, feldspar, and minor clays. The submicron-sized particles elutriated from the same soil consist mainly of mica, vermiculite, and smectite and occasional gibbsite. Autoradiography in conjunction with SEM analysis confirmed the association of radioactive Cs mainly with the submicron-sized particles. Up to ~3 MBq/kg of {sup 137}Cs are associated with the colloidal size fraction (<1 μm), which accounts for ~78% of the total radioactivity. Sequential extraction of the bulk sample revealed that most Cs was retained in the residual fraction, confirming the high binding affinity of Cs to clays, aluminosilicate sheet structures. The chemistry of the fraction containing submicron-sized particles from the same bulk sample showed a similar distribution to that of the bulk sample, again confirming that the Cs is predominantly adsorbed onto submicron-sized sheet aluminosilicates, even in the bulk soil samples. Despite the very small particle size, aggregation of the particles prevents migration in the vertical direction, resulting in the retention of >98% of Cs within top ~5 cm of the soil. These results suggest that the mobility of the aggregates of submicron-sized sheet aluminosilicate in the surface environment is a key factor controlling the current Cs

Achievement report for fiscal 1998. Esophageal vocalization aid system; 1998 nendo seika hokokusho. Shokudo hassei hojo sochi

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-05-01

Development has been made on element technologies for an esophageal vocalization aid system. With regard to the speaker, selection and trial production were performed on a speaker used for a phono-coupler to be used in coupling with a telephone transmitter. Performance not differing from that in the currently used telephone set was obtained in the overall characteristics evaluation using a dummy telephone circuitry. For the microphone, two kinds of hands-free microphones were fabricated on a trial basis. In order to develop pitch extraction and amplitude pitch conversion systems, pitch extraction performances were compared and discussed on the following five methods: the auto-correlation method, the Cepstram method, the average magnitude difference function (AMDF) method, the simplified inverse filter tracking (SIFT) method, and the time-domain excitation extractor using minimum perturbation operator (TEMPO) method. The hauling phenomenon, having come up as a problem in an auxiliary digital device, was analyzed to discuss methods for prevention thereof. In developing a voice/unvoiced distinction judgment method, a method using low domain power and high domain power was discussed. Development has been made on exclusive ICs, a voice analyzer, and the using feeling enhancing technology. In developing a total system, a digital unit incorporated esophageal vocalization aid system was developed and improved. (NEDO)

Estimation of Te-132 distribution in Fukushima Prefecture at the early stage of the Fukushima Daiichi Nuclear Power Plant reactor failures.

Science.gov (United States)

Tagami, Keiko; Uchida, Shigeo; Ishii, Nobuyoshi; Zheng, Jian

2013-05-21

Tellurium-132 ((132)Te, half-life: 3.2 d) has been assessed as the radionuclide with the third largest release from the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011; thus it would have made some dose contribution during the early stage of the reactor failures. The available data for (132)Te are, however, limited. In this study, available reported values of other isotopes of Te were compiled to estimate (132)Te concentration (in MBq m(-2)). It was found that (132)Te and (129m)Te (half-life: 33.6 d) concentrations were well correlated (R = 0.99, p < 0.001) by t test. Thus, (132)Te concentrations on March 11, 2011 were estimated from (129m)Te using the concentration conversion factor ((132)Te /(129m)Te) of 14.5. It was also found that since deposited (129m)Te was well retained in the soil, the data collected in March-May of 2011 were applicable to (132)Te estimation. It was possible to obtain the first (132)Te concentration contour map for the eastern part of Fukushima Prefecture, including data from within the 20-km exclusion zone around the FDNPP, using these newly available estimated (132)Te data sets.

Radioactive contamination of arthropods from different trophic levels in hilly and mountainous areas after the Fukushima Daiichi nuclear power plant accident.

Science.gov (United States)

Tanaka, Sota; Hatakeyama, Kaho; Takahashi, Sentaro; Adati, Tarô

2016-11-01

In order to understand the influence of the Fukushima Daiichi nuclear power plant accident on the ecosystem in hilly and mountainous areas of Fukushima Prefecture, chronological changes in the levels of radiocesium in arthropod species were investigated. From 2012 to 2014, arthropods from different trophic levels were sampled and the air radiation dose rates at the sampling sites were analyzed. The air radiation dose rates showed a significant and constant reduction over the 2 years at the sampling sites in Fukushima. The median radiocesium concentration ( 134 Cs +  137 Cs) detected in the rice grasshopper, Oxya yezoensis, and the Emma field cricket, Teleogryllus emma, dropped continuously to 0.080 and 0.078 Bq/g fresh weight, respectively, in 2014. In contrast, no significant reduction in radioactive contamination was observed in the Jorô spider, Nephila clavata, in which the level remained at 0.204 Bq/g in 2014. A significant positive correlation between radiocesium concentration and the air radiation dose rate was observed in the rice grasshopper, the Emma field cricket and the Jorô spider. The highest correlation coefficient (ρ = 0.946) was measured in the grasshopper. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Evaluation of radiocesium concentrations in new leaves of wild plants two years after the Fukushima Dai-ichi Nuclear Power Plant accident.

Science.gov (United States)

Sugiura, Yuki; Shibata, Michihiro; Ogata, Yoshimune; Ozawa, Hajime; Kanasashi, Tsutomu; Takenaka, Chisato

2016-08-01

Radiocesium ((137)Cs) transfer to plants immediately after the Fukushima Dai-ichi Nuclear Power Plant accident was investigated by collecting newly emerged leaf and soil samples between May 2011 and November 2012 from 20 sites in the Fukushima prefecture. Radiocesium concentrations in leaf and soil samples were measured to calculate concentration ratios (CR). Woody plants exhibited high CR values because (137)Cs deposited on stems and/or leaves were transferred to newly emerging tissues. The CR values in 2012 declined as compared to that in 2011. Exchangeable (137)Cs rates in soil (extraction rate) samples were measured at five sites. These rates decreased at four sites in 2012 and depended on environmental conditions and soil type. Both CR values and extraction rates decreased in 2012. However, CR values reflected the changes in extraction rates and characteristics of each species. Amaranthaceae, Chenopodiaceae, and Polygonaceae, which had been identified as Cs accumulators, presented no clear (137)Cs accumulation ability. In 2012, the perennial plant Houttuynia cordata and deciduous trees Chengiopanax sciadophylloides and Acer crataegifolium displayed high CR values, indicating that these species are (137)Cs accumulators and may be considered as potential species for phytoremediation. Copyright © 2016 Elsevier Ltd. All rights reserved.

[A Survey about the Radiation Effects and A Health Survey of Fukushima Inhabitants after the Fukushima Daiichi Nuclear Power Plant Accident].

Science.gov (United States)

Okazaki, Ryuji; Ohga, Kazuhiro; Yoko-O, Makoto; Kohzaki, Masaoki

According to questionnaire surveys in 2011 and 2013 about the health effects of radiation after the Fukushima Daiichi Nuclear Power Plant Accident, the guardians of child patients were more anxious than doctors and medical students. Also, according to the thyroid examinations in a Fukushima health survey, 190 cases of thyroid cancer were reported, and anxiety about radiation effects remained. This study is based on a survey about the guardians of child patients anxiety about radiation effects six years after the nuclear power plant accident, and includes a questionnaire survey about radiation effects and thyroid examinations in a Fukushima health survey. Anonymous question sheets with 20 questions were sent to pediatric medical facilities in Fukushima, and the parents of children who consulted the pediatric and medical staff answered the questionnaire. Thirty percent of the guardians of child patients had never been educated about radiation and 67% had never been educated about the effects of radiation on humans. The guardians of child patients were more anxious than the medical staff about thyroid cancer, health effects on children and genetic effects. Our results indicate that the guardians of child patients think that the increase in the incidence of thyroid cancer is due to radiation effects after the nuclear power plant accident and they desire continued thyroid examinations.

Updated synthesis of the knowledge about the impact on marine environment of the radioactive releases from Fukushima Dai-ichi damaged site - October 26, 2011; Synthese actualisee des connaissances relatives a l'impact sur le milieu marin des rejets radioactifs du site nucleaire accidente de Fukushima Dai-ichi - 26 octobre 2011

Energy Technology Data Exchange (ETDEWEB)

NONE

2011-10-26

A strong radioactive contamination of the marine environment close to the damaged Fukushima Dai-ichi power plant has been observed since March 21. The high concentration of some nuclides ({sup 131}I, {sup 137}Cs, {sup 134}Cs, {sup 136}Cs, {sup 132}Te, {sup 132}I) comes from three possible sources: the liquid effluents from the damaged site, the atmospheric fallouts, and the weathering of contaminated soils. This information note presents and comments the most recent informations gathered by the French institute of radiation protection and nuclear safety (IRSN) since the previous information note from July 11 and devoted to the same topic. It presents the estimation of the relative contribution of each contamination source and the evolution with time of the marine contamination. The mapping of {sup 137}Cs concentrations in surface seawater allows to estimate the amount of total {sup 137}Cs in the marine environment and its evolution with time. {sup 137}Cs and {sup 134}Cs concentrations were measured both in samples of surface coastal sediments and in river fishes and seafood products (mainly fishes and molluscs). Results are reported in graphs showing their evolution with time. (J.S.)

Uranium Dioxides and Debris Fragments Released to the Environment with Cesium-Rich Microparticles from the Fukushima Daiichi Nuclear Power Plant.

Science.gov (United States)

Ochiai, Asumi; Imoto, Junpei; Suetake, Mizuki; Komiya, Tatsuki; Furuki, Genki; Ikehara, Ryohei; Yamasaki, Shinya; Law, Gareth T W; Ohnuki, Toshihiko; Grambow, Bernd; Ewing, Rodney C; Utsunomiya, Satoshi

2018-03-06

Trace U was released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) during the meltdowns, but the speciation of the released components of the nuclear fuel remains unknown. We report, for the first time, the atomic-scale characteristics of nanofragments of the nuclear fuels that were released from the FDNPP into the environment. Nanofragments of an intrinsic U-phase were discovered to be closely associated with radioactive cesium-rich microparticles (CsMPs) in paddy soils collected ∼4 km from the FDNPP. The nanoscale fuel fragments were either encapsulated by or attached to CsMPs and occurred in two different forms: (i) UO 2+X nanocrystals of ∼70 nm size, which are embedded into magnetite associated with Tc and Mo on the surface and (ii) Isometric (U,Zr)O 2+X nanocrystals of ∼200 nm size, with the U/(U+Zr) molar ratio ranging from 0.14 to 0.91, with intrinsic pores (∼6 nm), indicating the entrapment of vapors or fission-product gases during crystallization. These results document the heterogeneous physical and chemical properties of debris at the nanoscale, which is a mixture of melted fuel and reactor materials, reflecting the complex thermal processes within the FDNPP reactor during meltdown. Still CsMPs are an important medium for the transport of debris fragments into the environment in a respirable form.

Thermodynamic evaluation of the solidification phase of molten core–concrete under estimated Fukushima Daiichi nuclear power plant accident conditions

Energy Technology Data Exchange (ETDEWEB)

Kitagaki, Toru, E-mail: kitagaki.toru@jaea.go.jp; Yano, Kimihiko; Ogino, Hideki; Washiya, Tadahiro

2017-04-01

The solidification phases of molten core–concrete under the estimated molten core–concrete interaction (MCCI) conditions in the Fukushima Daiichi Nuclear Power Plant Unit 1 were predicted using the thermodynamic equilibrium calculation tool, FactSage 6.2, and the NUCLEA database in order to contribute toward the 1F decommissioning work and to understand the accident progression via the analytical results for the 1F MCCI products. We showed that most of the U and Zr in the molten core–concrete forms (U,Zr)O{sub 2} and (Zr,U)SiO{sub 4}, and the formation of other phases with these elements is limited. However, the formation of (Zr,U)SiO{sub 4} requires a relatively long time because it involves a change in the crystal structure from fcc-(U,Zr)O{sub 2} to tet-(U,Zr)O{sub 2}, followed by the formation of (Zr,U)SiO{sub 4} by reaction with SiO{sub 2}. Therefore, the formation of (Zr,U)SiO{sub 4} is limited under quenching conditions. Other common phases are the oxide phases, CaAl{sub 2}Si{sub 2}O{sub 8}, SiO{sub 2}, and CaSiO{sub 3}, and the metallic phases of the Fe–Si and Fe–Ni alloys. The solidification phenomenon of the crust under quenching conditions and that of the molten pool under thermodynamic equilibrium conditions in the 1F MCCI progression are discussed.

Fiscal 2000 regional consortium research and development project - regional new technology creation research and development. Development of micro-array for next generation gene analysis (1st fiscal year); 2000 nendo chiiki consortium kenkyu kaihatsu jigyo - chiiki shingijutsu soshutsu kenkyu kaihatsu seika hokokusho. Jisedai idenshi kaiseki micro array no kaihatsu (daiichi nendo)

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

Efforts are under way to construct a novel DNA (deoxyribonucleic acid) micro-array for gene diagnosis on the basis of technologies of laser scan type manipulation, nanometric position detection, and micro-machining. Using these technologies, structural changes to accompany reactions induced in the probe DNA deposited on an array are detected for the identification of the DNA. Activities are conducted in the four fields of (1) the study of probe DNA fixation technology, (2) development of an optical detection system, (3) detailed check of DNA micro-array performance evaluation technologies, and (4) a comprehensive survey. In field (1), gold colloid modified DNA molecules are designed and evaluated, and the fixation of DNA to substrates and technologies for integration are studied. In field (2), the gold colloid modified DNA is fixed on a thin gold film, and then a surface plasmon resonance (SPR) is observed in the wake of hybridization. Furthermore, a Brownian motion is observed of the metal particles fixed on a glass substrate via DNA. (NEDO)

Fiscal 2000 regional consortium research and development project - regional new technology creation research and development. Practicalization of polymer back light (1st fiscal year); 2000 nendo chiiki consortium kenkyu kaihatsu jigyo - chiiki shingijutsu soshutsu kenkyu kaihatsu bun'ya seika hokokusho. Polymer back light no jitsuyoka ni kansuru kenkyu (daiichi nendo)

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

Efforts are being exerted to develop technologies for fabricating polyvinyl carbazole thin film, 100 nm or less in average thickness and 400 mm square in area, for the construction of an exothermal sheet utilizing polymer semiconductor light emission diodes. Activities are conducted in the three fields of (1) the development of large area light emission sheets for use in polymer LEDs (light emission diodes), (2) the study of manufacturing technologies, and (3) the study of technologies for testing, analyzing, and evaluating the material. In field (1), a polyvinyl carbazole thin film is fabricated by the use of a low viscosity resin liquid application method, and a film fabrication technique is established for fabricating a thin film on a 400 mm square substrate within {+-}3 nm of film thickness error. In field (2), studies are conducted of an integrated large area thin film application/transportation system, application device mechanisms, and control sequences for application devices. Through studies of technical literature, exhibitions, and research institute meetings in Japan and overseas, it is concluded that the polymer back light is commercially feasible. (NEDO)

Report of the results of the fiscal 1997 regional consortium R and D project. Regional consortium field / Development of 3D high speed bio-micromanipulation system (first fiscal year); 1997 nendo chiiki consortium kenkyu kaihatsu jigyo. Chiiki consortium bun`ya / sanjigen kosoku bio-micromanipulation system no kaihatsu (daiichi nendo) seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-03-01

This is aimed at developing a 3D high speed bio-micromanipulation system for small objects such as cells, bacteria and DNA. In fiscal 1997, a common platform for putting together and integrating individual technology owned by each member is trially fabricated, and the R and D of element technology to be integrated to it is divided up among members. As to selection/transportation technology, a basic experiment on screening by laser beams and electric field is conducted, and microfluid chips isolating bacteria are fabricated. Concerning positioning/fixation technology, cells and others which are comparatively larger than bacteria are freely positioned, and microdevices for fixation are trially fabricated. Relating to power measuring/controlling technology, developed is a multi-freedom degree contact type micromanipulator and a multi-axial minute sensor which enables the 3D mechanical manipulation of cells of the above-mentioned size, etc. The minute processing technology is developed to trially fabricate various microdevices which are integrated into the common flatform. 42 refs., 89 figs., 9 tabs.

The accident at TEPCO's Fukushima-Daiichi Nuclear Power Station: What went wrong and what lessons are universal?

Science.gov (United States)

Omoto, Akira

2013-12-01

After a short summary of the nuclear accident at the Fukushima Daiichi Nuclear Power Station, this paper discusses “what went wrong” by illustrating the problems of the specific layers of defense-in-depth (basic strategy for assuring nuclear safety) and “what lessons are universal.” Breaches in the multiple layers of defense were particularly significant in respective protection (a) against natural disasters (first layer of defense) as well as (b) against severe conditions, specifically in this case, a complete loss of AC/DC power and isolation from the primary heat sink (fourth layer of defense). Confusion in crisis management by the government and insufficient implementation of offsite emergency plans revealed problems in the fifth layer of defense. By taking into consideration managerial and safety culture that might have relevance to this accident, in the author's view, universal lessons are as follows: Resilience: the need to enhance organizational capabilities to respond, monitor, anticipate, and learn in changing conditions, especially to prepare for the unexpected. This includes increasing distance to cliff edge by knowing where it exists and how to increase safety margin. Responsibility: the operator is primarily responsible for safety, and the government is responsible for protecting public health and environment. For both, their right decisions are supported by competence, knowledge, and an understanding of the technology, as well as humble attitudes toward the limitations of what we know and what we can learn from others. Social license to operate: the need to avoid, as much as possible regardless of its probability of occurrence, the reasonably anticipated environmental impact (such as land contamination), as well as to build public confidence/trust and a renewed liability scheme.

Off-shore contamination by I-131 and Cs-137 from the Fukushima Daiichi nuclear power station accident

International Nuclear Information System (INIS)

Pereira, Wagner de Souza; Kelecom, Patrick Vicent; Miyashita, Erika; Universidade Federal Fluminense; Kelecom, Alphonse

2011-01-01

On March 11, 2011 the biggest earthquake ever registered in Japan severed off-site power supply to the Fukushima Daiichi Nuclear Power Station. Backup diesel generators began providing electricity to pumps circulating coolant to the reactors, but were knocked out by a large tsunami and the nuclear site lost the ability to maintain proper reactor cooling. This was the beginning of a huge nuclear accident that was assigned an INES maximum rating of 7. On March 21, Japanese authorities reported that the Tokyo Electric Power Company (TEPCO) had detected radioactive materials in seawater. Radioactivity started to be measured by the Japan Atomic Energy Agency every two days in sea water from eight locations, 30km from the coastline. I-131 and Cs-137 were analyzed among other radionuclides. It is the aim of this paper to gather all this information and to discuss the evolution of the radioactive marine contamination during the first month of the accident. Results indicate for surface seawater concentrations ranging from 24.9 to 161.0 Bq/L for I-131 and 11.2 to 186.0 Bq/L for Cs-137, and for deep waters of 1.59-15.0 Bq/L (I-131) and 0.0-11.4 Bq/L (Cs-137). The I-131 concentrations in superficial waters were at or above Japanese regulatory limits in the first days, then lowered during one week to increase again above limits when TEPCO released contaminated water into the ocean, to finally reach not detectable values the last week of April. With the exception of point 4, on April 15, the Cs-137 levels were always well below regulatory limits. (author)

Robustness of Electrical Systems of Nuclear Power Plants in Light of the Fukushima Daiichi Accident (ROBELSYS). Workshop Proceedings, Paris, France, 1-4 April 2014 - Robustness of Electrical Systems of NPP's in Light of the Fukushima Daiichi Accident. ROBELSYS Workshop Proceedings

International Nuclear Information System (INIS)

2015-01-01

The March 2011 accident at Fukushima Daiichi triggered discussions about the significance of electrical power hazards and their treatment in safety analyses. In order to address these issues and provide relevant conclusions and recommendations to CSNI and CNRA, the Robustness in Electrical Systems (ROBELSYS) Technical Working Group was established in 2012 under the leadership of the Institut de Radioprotection et de Surete Nucleaire (IRSN) of France. The purpose of the ROBELSYS Technical Working Group was to organize an international workshop to identify and discuss the lessons learned from the Fukushima Daiichi accident. The workshop was focused on the provisions taken by various countries concerning national requirements and modifications to the plant designs in order to enhance the robustness of electrical systems, especially the protection against extreme external hazards. The ROBELSYS workshop was held at the OECD Conference Centre in Paris in April 1-4, 2014. A total of 105 participants attended the workshop representing industry and government organisations from 25 countries, as well as international organisations. A total of 34 technical presentations were given in seven sessions as follows: - 1: National Programmes on Evolution of Onsite and Offsite Electric Power Systems; - 2: Role of Electric Power in Severe Accident Management; - 3: Requirements for Robustness of Onsite Electric Power Systems; - 4: Simulation of Transients within NPP Plant Distribution Systems; - 5: Requirements for Equipment Used for Emergency Response; - 6: Margin Assessments for Modern Power Electronics; - 7: Digital Components in Power Systems. Items addressed in the workshop included: - Review of the lessons learned from the Fukushima accident concerning the robustness of electrical systems; - Review of the provisions already taken or planned after the Fukushima accident, regarding the sources, the distribution systems and the loads, and documenting the technical basis for these

Decision no. 2011-DC-0215 of the French nuclear safety authority from May 5, 2011, ordering ITER Organization to proceed to a complementary safety evaluation of its basic nuclear facility in the eyes of the Fukushima Daiichi nuclear power plant accident

International Nuclear Information System (INIS)

2011-01-01

As a consequence of the accident of the Fukushima Daiichi nuclear power plant (Japan), the French Prime Minister entrusted the French nuclear safety authority (ASN) with the mission to carry out a safety analysis re-evaluation of the French nuclear facilities, and in particular the nuclear power plants. A decision has been addressed by the ASN to each nuclear operator with the specifications of this safety re-evaluation analysis and the list of facilities in concern. This document is the decision addressed to the ITER Organization, operator of the ITER tokamak facility of Cadarache (France). (J.S.)

Visualization of recognition on the biological effects of low-dose radiation through a survey of the scientists. Taking an accident at Fukushima Daiichi Nuclear Power Plant as an example

International Nuclear Information System (INIS)

Takayasu, Kenta; Onoue, Yousuke; Koyamada, Kouji; Konami, Hideo; Manabe, Yuichirou; Bando, Masako

2017-01-01

Since Fukushima Daiichi Nuclear Accident caused by the Great East Japan Earthquake, radiation exposure problem has been discussed among government agencies, medical personnels, scientists, and so on. At that time, people were confused by pendulumlike instructions of the Japanese government and scientists. It is said that there are multiple academic fields which related to radiation exposure problem and they need to be interdisciplinary. We think that the confusion is due to lack of mutual understanding among various academic fields and insufficiency of interdisciplinary communication. In this work, we investigated the current situation of interdisciplinary communication among these fields through the radiation exposure problem by our questionnaire survey and researched what problem is attributed to. From the result, character of each academic field and their communality are clarified. We believe this result leads us to propose the true way of interdisciplinary research and communication of different academic fields. (author)

Review of the international forum on peaceful use of nuclear energy and nuclear security. Taking the lessons learned from Fukushima Daiichi Nuclear Power Plant accident to the 2012 Seoul nuclear security summit

International Nuclear Information System (INIS)

Tazaki, Makiko; Suda, Kazunori; Suzuki, Mitsutoshi; Kuno, Yusuke; Mochiji, Toshiro

2012-06-01

The Japan Atomic Energy Agency (JAEA) held '2011 International Forum on the Peaceful Use of Nuclear Energy and Nuclear Security - Taking the lessons learned from Fukushima Daiichi Nuclear Power Plant Accident to the 2012 Seoul Nuclear Security Summit-' on 8 and 9 December, 2011. It intended to articulate effective strategies and measures for strengthening nuclear security using lessons learned from the Fukushima Nuclear Accident. Moreover, it was expected to explore comprehensive approaches which could contribute to enhancing both nuclear safety and security in order to support sustainable and appropriate development of the peaceful use of nuclear energy. This report includes abstracts of keynote speeches, summary of panel discussions and materials of the presentations in the forum. The editors take full responsibility for the wording and content of this report, excepts presentation materials. (author)

Review of the international forum on peaceful use of nuclear energy and nuclear security. Taking the lessons learned from Fukushima Daiichi Nuclear Power Plant accident to the 2012 Seoul nuclear security summit

Energy Technology Data Exchange (ETDEWEB)

Tazaki, Makiko; Suda, Kazunori; Suzuki, Mitsutoshi; Kuno, Yusuke; Mochiji, Toshiro [Japan Atomic Energy Agency, Department of Science and Technology for Nuclear Material Management, Tokai, Ibaraki (Japan)

2012-06-15

The Japan Atomic Energy Agency (JAEA) held '2011 International Forum on the Peaceful Use of Nuclear Energy and Nuclear Security - Taking the lessons learned from Fukushima Daiichi Nuclear Power Plant Accident to the 2012 Seoul Nuclear Security Summit-' on 8 and 9 December, 2011. It intended to articulate effective strategies and measures for strengthening nuclear security using lessons learned from the Fukushima Nuclear Accident. Moreover, it was expected to explore comprehensive approaches which could contribute to enhancing both nuclear safety and security in order to support sustainable and appropriate development of the peaceful use of nuclear energy. This report includes abstracts of keynote speeches, summary of panel discussions and materials of the presentations in the forum. The editors take full responsibility for the wording and content of this report, excepts presentation materials. (author)

Radiation control in the core shroud replacement project of Fukushima-Daiichi NPS Unit no.2

International Nuclear Information System (INIS)

Kokubun, Yasunori; Haraguchi, Kazuyuki; Yoshizawa, Yuji; Yamada, Yasuo

2000-01-01

In Fukushima-Daiichi NPS Unit no.2, the core shroud replacement was made following that of Unit no.3. This project involves replacement of wide-ranging equipment, with the project extending over a long period of time. This was expected to increase the dose equivalent of workers. Accordingly, various measures to lower the dose equivalent were planned and implemented. We outline radiation controls implemented during the project period. The shroud replacement project was a preventive maintenance project which consisted of replacing the core shroud and other internals with those less susceptible to stress corrosion cracking. Problems related to radiation control during the replacement project of Unit no.3 the year before last were summarized. We studied, planned, and implemented measures to be reflected in the project for Unit no.2. This was done to lower the dose equivalent as much as possible while paying due attention to safety and economy. For radiation control during the project for Unit no.2, experiments with Unit no.3 were fully exploited and any effective measures taken at that time were adopted in this project. Problems pointed out after that project with Unit no.3 resulted in new or improved measures being taken with Unit no.2. Measures taken over from the project with Unit no.3; a. Daily analysis of difference between expected and actual dose equivalents b. Dose reduction measures, chemical decontamination, temporary shield, flushing, etc.; New or improved measures; a. Dose reduction measures: Mechanical removal of radiation sources, strengthening of shield, etc.; b. Automatic remote control system; c. Use of new protective devices. With measures implemented as described above, the dose equivalent during shroud replacement of Unit no.2 was reduced by about 30% when compared with that (11.5 persons · Sv) in the case of Unit no.3. Implemented radiation controls will be checked and reviewed in future for reflection in projects with other units. (author)

Time changes in radiocesium concentration in aquatic systems affected by the Fukushima Daiichi NPP accident

Science.gov (United States)

Onda, Yuichi; Taniguchi, Keisuke; Kato, Hiroaki; Yoshimura, Kazuya; Wakiyama, Yoshifumi; Iwagami, Sho; Tsujimura, Maki; Sakaguchi, Aya; Yamamoto, Masatoshi

2015-04-01

Due to Fukushima Daiichi Nuclear Power Plant accident, radioactive materials including Cs-134 and Cs-137 were widely distributed in surrounded area. The radiocesiums have been transported in river networks. The monitoring started at 6 sites from June 2011. Subsequently, additional 24 monitoring sites were installed between October 2012 and January 2013. Flow and turbidity (for calculation of suspended sediment concentration) were measured at each site, while suspended sediments and river water were collected every one or half month to measure Cs-134 and Cs-137 activity concentrations by gamma spectrometry. Also detailed field monitoring has been condcuted in Yamakiya-district, Kawamata town, Fukushima prefecture. These monitoring includes, 1) Radiocesium wash-off from the runoff-erosion plot under different land use, 2) 2. Measurement of radiocesium transfer in forest environment, in association with hydrological pathways such as throughfall and overlandflow on hillslope, 3) Monitoring on radiocesium concentration in soil water, ground water, and spring water, 4)Monitoring of dissolved and particulate radiocesium concentration in river water, and stream water from the forested catchment, and 5)Measurement of radiocesium content in drain water and suspended sediment from paddy field. Our monitoring result demonstrated that the Cs-137 concentration in eroded sediment from the runoff-erosion plot has been almost constant for the past 3 years, however the Cs-137 concentration of suspended sediment from the forested catchment showed slight decrease through time. On the other hand, the suspended sediment from paddy field and those in river water from large catchments exhibited rapid decrease in Cs-137 concentration with time. The decreasing trend of Cs-137 concentration were fitted by the two-component exponential model, differences in decreasing rate of the model were compared and discussed among various land uses and catchment scales. Such analysis can provide

Corrosion resistance of tank material for flock storage in the Fukushima Daiichi Nuclear Power Plant

International Nuclear Information System (INIS)

Sano, Yuichi; Anbai, Hiromu; Takeuchi, Masayuki; Ogino, Hideki; Koizumi, Kenji

2014-01-01

The installation of the storage tank made of SS400 is under planning in the Fukushima Daiichi nuclear power plant for the flock which was generated in the coagulation process for radioactive contaminated water. The flock contains the seawater and has a possibility to make a crevice and local corrosion on the surface of the tank. Air agitation will be applied in the storage tank to prevent the accumulation of the flock and hydrogen generated by radiolysis, which will increase the diffusion of oxygen and the corrosion of SS400. In addition, the effect of radiation from the flock on the corrosion should be considered. In this study, we investigated the corrosion behavior of SS400 in the flock under the aeration-agitation condition with γ-ray irradiation. Based on the flock storage condition announced by Tokyo Electric Power Company (TEPCO), immersion tests were performed with SS400 coupons under several conditions and corrosion rates were estimated by the weight loss of the coupons. After the immersion tests, the surfaces of the coupons were observed by microscopy for evaluating the local corrosion. To evaluate corrosion mechanism in detail, electrochemical tests were also carried out. In all of these tests, the non-radioactive flock as a surrogate and artificial seawater were used. Corrosion rates of SS400 increased significantly with aeration flow rates in the seawater with/without the flock, but this tendency was weaker in the seawater with the flock, especially under the condition where coupons were buried in the flock. The electrochemical tests indicated the suppression of the cathodic reaction, i.e. dissolved oxygen reduction, in the seawater with the flock. The effect of γ-ray irradiation on the corrosion rates was not remarkable under the assumed dose rate. Microscopic analysis of the immersed coupons showed no severe corrosion including local corrosion occurred. The corrosion rate could be decreased effectively by suppressing the dissolved oxygen reduction

Impact of the Fukushima Daiichi nuclear power plant accident on local community and healthcare services

International Nuclear Information System (INIS)

Oikawa, Tomoyoshi

2013-01-01

The Soso region of Japan, located in the northern part of the Pacific side of Fukushima Prefecture, has suffered tremendously from widespread damage caused by the earthquake, tsunami and the Fukushima Dai-ichi nuclear power plant accident. Immediately after the disaster it even seemed that the restoration of this region itself would not be possible. However after six months, the Indoor Restriction Order and evacuation orders within a 20 to 30 km zone from the plant, such as the Evacuation-Prepared Area in Case of Emergency, were lifted and all of those restrictions for the planned evaluation zone has been eased in line with the actual conditions of each region. A year and a month after the earthquake, the Caution Zone, which was declared to prohibit the entry to the zone within the 20 km radius from the plant, was lifted. Thus people can now enter as close as 10 km from the plant. Minami-Soma city is an administrative district which had the largest population (approximately 71,500 residents) within the 20 to 30 km zone prior to the earthquake. It was, also, the only district where the evacuation was not conducted by the municipality. The city is now called the Genpatsu frontline district as it is the closest city to the plant where people have continued to live. Due to the damage caused by the earthquake and Tsunami, the city has suffered both from destruction by the tsunami and radiation, and people are still facing numerous problems despite the fact that the city appears to have been restored on its surface. It is very unfortunate that much of the medical data from the region was lost in the confusion after the Great East Japan Earthquake. In this paper various facts after the disaster based on the data left in the So-so region, Minamisoma city, and Minamisoma municipal general hospital are reported. (author)

New regulations for radiation protection for work involving radioactive fallout emitted by the TEPCO Fukushima Daiichi APP accident--disposal of contaminated soil and wastes.

Science.gov (United States)

Yasui, Shojiro

2014-01-01

The accident at the Fukushima Daiichi Atomic Power Plant that accompanied the Great East Japan Earthquake on March 11, 2011, released a large amount of radioactive material. To rehabilitate the contaminated areas, the government of Japan decided to carry out decontamination work and manage the waste resulting from decontamination. In the summer of 2013, the Ministry of the Environment planned to begin a full-scale process for waste disposal of contaminated soil and wastes removed as part of the decontamination work. The existing regulations were not developed to address such a large amount of contaminated wastes. The Ministry of Health, Labour and Welfare (MHLW), therefore, had to amend the existing regulations for waste disposal workers. The amendment of the general regulation targeted the areas where the existing exposure situation overlaps the planned exposure situation. The MHLW established the demarcation lines between the two regulations to be applied in each situation. The amendment was also intended to establish provisions for the operation of waste disposal facilities that handle large amounts of contaminated materials. Deliberation concerning the regulation was conducted when the facilities were under design; hence, necessary adjustments should be made as needed during the operation of the facilities.

Municipalities' opinions about decontamination in special decontamination area. Records from three and a half years after the Fukushima Daiichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Kawasaki, Kota

2015-01-01

This study discusses opinions of 11 municipalities in Fukushima Prefecture designated as Special Decontamination Area as of the end of September 2014, about three and a half years after the Fukushima Daiichi Nuclear Power Plant accident. This study shows that (1) more than half of the municipalities recognize that decontamination activities of the national government which is responsible for decontamination in Special Decontamination Area are inadequate, (2) more than half of the municipalities recognize that residents cannot live their lives with a sense of safety and security unless air radiation dose is reduced to the level before the accident or less than 0.23 μSv/h, and (3) many municipalities recognize that residents will not be able to live their lives with a sense of safety and security even if the national government implements decontamination, (4) many municipalities points out 'Inability to secure enough temporary storage sites' and 'Inappropriateness of the decontamination policy and methods for forests or reservoir' as problems for the promotion of decontamination, and (5) almost all the municipalities recognize the necessity of the installation of interim storage facilities to accelerate the reconstruction of towns. (author)

Updated synthesis of the knowledge about the impact on marine environment of the radioactive releases from Fukushima Dai-ichi damaged site - October 26, 2011

International Nuclear Information System (INIS)

2011-01-01

A strong radioactive contamination of the marine environment close to the damaged Fukushima Dai-ichi power plant has been observed since March 21. The high concentration of some nuclides ( 131 I, 137 Cs, 134 Cs, 136 Cs, 132 Te, 132 I) comes from three possible sources: the liquid effluents from the damaged site, the atmospheric fallouts, and the weathering of contaminated soils. This information note presents and comments the most recent informations gathered by the French institute of radiation protection and nuclear safety (IRSN) since the previous information note from July 11 and devoted to the same topic. It presents the estimation of the relative contribution of each contamination source and the evolution with time of the marine contamination. The mapping of 137 Cs concentrations in surface seawater allows to estimate the amount of total 137 Cs in the marine environment and its evolution with time. 137 Cs and 134 Cs concentrations were measured both in samples of surface coastal sediments and in river fishes and seafood products (mainly fishes and molluscs). Results are reported in graphs showing their evolution with time. (J.S.)

Soil sampling and analytical strategies for mapping fallout in nuclear emergencies based on the Fukushima Dai-ichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Onda, Yuichi; Kato, Hiroaki; Hoshi, Masaharu; Takahashi, Yoshio; Nguyen, Minh-Long

2015-01-01

The Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident resulted in extensive radioactive contamination of the environment via deposited radionuclides such as radiocesium and 131 I. Evaluating the extent and level of environmental contamination is critical to protecting citizens in affected areas and to planning decontamination efforts. However, a standardized soil sampling protocol is needed in such emergencies to facilitate the collection of large, tractable samples for measuring gamma-emitting radionuclides. In this study, we developed an emergency soil sampling protocol based on preliminary sampling from the FDNPP accident-affected area. We also present the results of a preliminary experiment aimed to evaluate the influence of various procedures (e.g., mixing, number of samples) on measured radioactivity. Results show that sample mixing strongly affects measured radioactivity in soil samples. Furthermore, for homogenization, shaking the plastic sample container at least 150 times or disaggregating soil by hand-rolling in a disposable plastic bag is required. Finally, we determined that five soil samples within a 3 m × 3-m area are the minimum number required for reducing measurement uncertainty in the emergency soil sampling protocol proposed here. - Highlights: • Emergency soil sampling protocol was proposed for nuclear hazards. • Various sampling procedures were tested and evaluated in Fukushima area. • Soil sample mixing procedure was of key importance for measured radioactivity. • Minimum number of sampling was determined for reducing measurement uncertainty

Determination of local-area distribution and relocation of radioactive cesium in trees from Fukushima Daiichi Nuclear Power Plant by autoradiography analysis

International Nuclear Information System (INIS)

Sakamoto, Fuminori; Ohnuki, Toshihiko; Kozai, Naofumi; Yamasaki, Shinya; Yoshida, Zenko; Nanba, Kenji

2013-01-01

The local area distribution and relocation of radioactive cesium deposited in trees after the 2011 tsunami-related accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) have been studied by measuring the spatial distribution of cesium on/in trees by autoradiography analysis. Samples of trees were collected from places located between 4 and 55 km from FDNPP approximately 2, 8, 20, and 22 months after the accident. The autoradiography analyses of Cryptomeria japonica, Torreya nucifera, and Thujopsis dolabrata var. hondae samples collected approximately 2 and 8 months after the accident showed that radioactive Cs was mainly distributed as spots on the branches and leaves of the trees emerged before the accident, and was detected in negligible amounts in new branch and leaves that emerged after the accident. On the contrary, radioactive Cs was detected at the outermost tip of the branches in the trees collected 20 months after the accident. Morus alba samples collected 22 months after the accident contained radioactive Cs inside and outside their stems, even though no radioactive Cs was detected in their roots, strongly suggesting that a certain amount of radioactive Cs was translocated from the outside to the inside of stems. These results indicate that the distribution of radioactive Cs deposited on/in the trees gradually changes with time (scale: year). (author)

Suggestion of typical phases of in-vessel fuel-debris by thermodynamic calculation for decommissioning technology of Fukushima-Daiichi nuclear power station

Energy Technology Data Exchange (ETDEWEB)

Ikeuchi, Hirotomo; Yano, Kimihiko; Kaji, Naoya; Washiya, Tadahiro [Japan Atomic Energy Agency, 4-33 Muramatsu, Tokai-mura, Ibaraki-ken, 319-1194 (Japan); Kondo, Yoshikazu; Noguchi, Yoshikazu [PESCO Co.Ltd. (Korea, Republic of)

2013-07-01

For the decommissioning of the Fukushima-Daiichi Nuclear Power Station (1F), the characterization of fuel-debris in cores of Units 1-3 is necessary. In this study, typical phases of the in-vessel fuel-debris were estimated using a thermodynamic equilibrium (TDE) calculation. The FactSage program and NUCLEA database were applied to estimate the phase equilibria of debris. It was confirmed that the TDE calculation using the database can reproduce the phase separation behavior of debris observed in the Three Mile Island accident. In the TDE calculation of 1F, the oxygen potential [G(O{sub 2})] was assumed to be a variable. At low G(O{sub 2}) where metallic zirconium remains, (U,Zr)O{sub 2}, UO{sub 2}, and ZrO{sub 2} were found as oxides, and oxygen-dispersed Zr, Fe{sub 2}(Zr,U), and Fe{sub 3}UZr{sub 2} were found as metals. With an increase in zirconium oxidation, the mass of those metals, especially Fe{sub 3}UZr{sub 2}, decreased, but the other phases of metals hardly changed qualitatively. Consequently, (U,Zr)O{sub 2} is suggested as a typical phase of oxide, and Fe{sub 2}(Zr,U) is suggested as that of metal. However, a more detailed estimation is necessary to consider the distribution of Fe in the reactor pressure vessel through core-melt progression. (authors)

Decision no. 2011-DC-0222 of the French nuclear safety authority from May 5, 2011, ordering the Comurhex company to proceed to a complementary safety evaluation of some of its basic nuclear facilities in the eyes of the Fukushima Daiichi nuclear power plant accident

International Nuclear Information System (INIS)

2011-01-01

As a consequence of the accident of the Fukushima Daiichi nuclear power plant (Japan), the French Prime Minister entrusted the French nuclear safety authority (ASN) with the mission to carry out a safety analysis re-evaluation of the French nuclear facilities, and in particular the nuclear power plants. A decision has been addressed by the ASN to each nuclear operator with the specifications of this safety re-evaluation analysis and the list of facilities in concern. This document is the decision addressed to Comurhex company, operator of the Tricastin uranium conversion plant (France). (J.S.)

A Comparative Analysis of the Impact of the IAEA Cooperation Instruments in the Field of Nuclear Safety to Deal with the Fukushima Daiichi Accident vis-a-vis the Chernobyl Accident

International Nuclear Information System (INIS)

Da Silva Simões, V.

2016-01-01

On 26 April 1986, an explosion at Unit 4 at the Chernobyl nuclear power plant released a very large amount of radioactive material into the atmosphere. According to the conclusions raised at the “International Forum on Chernobyl´s Nuclear Safety Aspects” held in Vienna from 1 to 3 April 1996, two important causes of the accident were that: “there were significant deficiencies in the design of the reactor – in particular of its shutdown system – and operating procedures were severely violated at the time of the accident” and “there was a lack of safety culture in the organizations responsible for operation and for control: important safety weaknesses had been recognized long before the accident occurred but were not remedied.” Only thanks to the discovery of an increase in environmental radioactivity in Nordic countries the international community was informed about the accident. On 11 March 2011, as one of the consequences of the tsunami waves generated by the Great East Japan Earthquake off the Pacific coast of Japan, the Fukushima Daiichi nuclear power plant accident took place. In his statement to the “International Conference on Chernobyl: Twenty-Five Years On - Safety for the Future” the International Atomic Energy Agency Director General, Mr. Yukiya Amano, pointed out “Chernobyl led to a great step forward in international cooperation in the field of nuclear safety. We now have four safety conventions, two Codes of Conduct, fundamental safety principles and a body of globally recognised IAEA Safety Standards.” [ ] “An international coordinated response system, with the IAEA's Incident and Emergency Centre at its heart, is now in place.” [ ] “We also have an IAEA peer review system, based on the Agency's Safety Standards.” But Mr. Amano also recognized that “despite the great progress made in the last 25 years, more needs to be done to ensure that a ''Safety First'' approach becomes fully

INITIAL AND PRESENT SITUATION OF FOOD CONTAMINATION IN JAPAN AFTER THE ACCIDENT AT THE FUKUSHIMA DAI-ICHI NUCLEAR POWER PLANT.

Science.gov (United States)

Aono, Tatsuo; Yoshida, Satoshi; Akashi, Makoto

2016-09-01

The accident at the Fukushima Dai-ichi Nuclear Power Plant (NPP) in March 2011 affected not only the terrestrial environment of Fukushima prefecture and the surrounding area, but also the marine area facing the NPP. Our present study is focused on the concentrations of radionuclides in agricultural products of Fukushima and sea-foods collected off Fukushima after the accident. The regulation value for radiocesium in vegetables, meat and fish was revised from 500 Bq/kg-wet to 100 Bq/kg-wet on 1 April 2012. The overall activity of radiocesium in these products was found to be within the limit of tolerance in respect to Japanese and also international regulations, but there is still radiocesium found at activities greater than this level in edible wild plants, wild mushrooms and game such as boar meat. Although the activities of radionuclides exceeding the regulatory limits were not detected in marine products collected off Fukushima after April 2015, the commercial marine fishery has not received approval in the affected areas except for certain species. We learned from the Fukushima accident that long-term kinetic studies of radionuclides in terrestrial and marine environments is extremely important for prevention of internal contamination, since contamination with radionuclides occurs via the food chain in the environment. © World Health Organisation 2016. All rights reserved. The World Health Organization has granted Oxford University Press permission for the reproduction of this article.

Concentration levels of cesium-137 in soils of the municipalities of Guadalupe and Zacatecas before the accident of Fukushima Daiichi

International Nuclear Information System (INIS)

Mireles, F.; Davila, J. I.; Pinedo, J. L.; Lopez, H.; Rios, C.; Saucedo, S. A.; Flores, F. E.

2011-11-01

The study of the emitter radioisotopes of gamma-rays in soil is very important considering damages to the health and quality of the environment. The main objective of this work is the study of the concentration of the artificial radioisotope 137 Cs in soil of the cities and municipalities of Zacatecas and Guadalupe of the Zacatecas State, Mexico. The study was carried out in two stages for different times, the first stage corresponded to the cities of Zacatecas and Guadalupe in 2000; and the second corresponded to the municipalities of Zacatecas and Guadalupe in 2008. The first study region was the cities of Zacatecas and Guadalupe, and environs where 20 soil samples were obtained. The second study region was inside the municipalities of Guadalupe and Zacatecas and 44 samples of near soil to the communities with major population in both municipalities were obtained. A spectrometry system of gamma-rays was used based on a coaxial detector of germanium hyper pure of high resolution, and was calculated the concentration of the 137 Cs with the energy photo-pick 661.66 KeV. In this work the activity concentrations of the 137 Cs in soil are presented and their variation in function of the time. These data will be a reference to evaluate a possible increment of the 137 Cs because of the accident of Fukushima Daiichi (Japan) nuclear power plant happened March 11, 2011. (Author)

Novel method for estimation of the indoor-to-outdoor airborne radioactivity ratio following the Fukushima Daiichi Nuclear Power Plant accident

Energy Technology Data Exchange (ETDEWEB)

Tan, Yanliang, E-mail: hytyl@163.com [College of Physics and Electronic Engineering, Hengyang Normal University, Hengyang, Hunan Province (China); Ishikawa, Tetsuo [Fukushima Medical University, 1 Hikariga-oka, Fukushima (Japan); Janik, Miroslaw [Regulatory Science Research Program, National Institute of Radiological Sciences, Chiba (Japan); Tokonami, Shinji [Department of Radiation Physics, Institute of Radiation Emergency Medicine, Hirosaki University, Hirosaki, Aomori (Japan); Hosoda, Masahiro [Hirosaki University Graduate School of Health Science, Hirosaki, Aomori (Japan); Sorimachi, Atsuyuki [Fukushima Medical University, 1 Hikariga-oka, Fukushima (Japan); Kearfott, Kimberlee [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI (United States)

2015-12-01

The accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Japan resulted in significant releases of fission products. While substantial data exist concerning outdoor air radioactivity following the accident, the resulting indoor radioactivity remains pure speculation without a proper method for estimating the ratio of the indoor to outdoor airborne radioactivity, termed the airborne sheltering factor (ASF). Lacking a meaningful value of the ASF, it is difficult to assess the inhalation doses to residents and evacuees even when outdoor radionuclide concentrations are available. A simple model was developed and the key parameters needed to estimate the ASF were obtained through data fitting of selected indoor and outdoor airborne radioactivity measurement data obtained following the accident at a single location. Using the new model with values of the air exchange rate, interior air volume, and the inner surface area of the dwellings, the ASF can be estimated for a variety of dwelling types. Assessment of the inhalation dose to individuals readily follows from the value of the ASF, the person's indoor occupancy factor, and the measured outdoor radioactivity concentration. - Highlights: • Actual ASF of the dwells is very important to estimate the inhalation dose. • A simple model is developed to describe ASF. • The key parameter of ASF is obtained from the measurement of NIRS. • The ASF of any dwellings can be obtained by our model and relatively parameters.

Summary of the foreign countries reports on the Fukushima Daiichi Nuclear Power Plants accident, on the lessons learnt and recommendation

International Nuclear Information System (INIS)

Nariai, Hideki

2017-01-01

This paper focused on the lessons and recommendations from the accident investigation reports prepared by the National Academy of Sciences (NAS), IAEA, and OECD/NEA on the accident of Fukushima Daiichi Nuclear Power Station associated with the Great East Japan Earthquake. (1) As for the causes of the accident, the IAEA report pointed out as a technical factor that Japan's scientists did not think that the earthquake occurrence probability of the magnitude 9 as an external event was high. As for tsunami countermeasures, it reported that accident countermeasures would have been easier if only seawater pump flood protection and the high-elevation positioning of emergency power supply etc. were prepared. As for human organizational factor, it pointed out that nuclear regulations were performed by many divided organizations, and responsibility and authority were not clear. The NAS report pointed out that the regulatory agency and nuclear promotion agency were not functionally separated, and that the regulatory agency was not independent as a result of the relationship between the Japanese government agency and companies, and the agency became a captive of regulations. The following items were also reported; (2) safety measures and emergency preparedness, (3) off-site response during emergency, (4) radiation effects, (5) restoration after the accident, (6) international issues, and (7) issues of the spent fuel storage pool of NAS. Japan established the Nuclear Regulation Authority by integrating related organizations, but how to create a regulatory agency with advanced expertise is the future task. (A.O.)

The accident at TEPCO's Fukushima-Daiichi Nuclear Power Station: What went wrong and what lessons are universal?

International Nuclear Information System (INIS)

Omoto, Akira

2013-01-01

After a short summary of the nuclear accident at the Fukushima Daiichi Nuclear Power Station, this paper discusses “what went wrong” by illustrating the problems of the specific layers of defense-in-depth (basic strategy for assuring nuclear safety) and “what lessons are universal.” Breaches in the multiple layers of defense were particularly significant in respective protection (a) against natural disasters (first layer of defense) as well as (b) against severe conditions, specifically in this case, a complete loss of AC/DC power and isolation from the primary heat sink (fourth layer of defense). Confusion in crisis management by the government and insufficient implementation of offsite emergency plans revealed problems in the fifth layer of defense. By taking into consideration managerial and safety culture that might have relevance to this accident, in the author's view, universal lessons are as follows: a)Resilience: the need to enhance organizational capabilities to respond, monitor, anticipate, and learn in changing conditions, especially to prepare for the unexpected. This includes increasing distance to cliff edge by knowing where it exists and how to increase safety margin. b)Responsibility: the operator is primarily responsible for safety, and the government is responsible for protecting public health and environment. For both, their right decisions are supported by competence, knowledge, and an understanding of the technology, as well as humble attitudes toward the limitations of what we know and what we can learn from others. c)Social license to operate: the need to avoid, as much as possible regardless of its probability of occurrence, the reasonably anticipated environmental impact (such as land contamination), as well as to build public confidence/trust and a renewed liability scheme

A backward method to estimate the Dai-ichi reactor core damage using radiation exposure in the environment

International Nuclear Information System (INIS)

PM Udiyani; S Kuntjoro; S Widodo

2016-01-01

The Fukushima accident resulted in the melting of the reactor core due to loss of supply of coolant when the reactor stopped from operating conditions. The earthquake and tsunami caused loss of electricity due to the flooding that occurred in the reactor. The absence of the coolant supply after reactor shutdown resulted in heat accumulation, causing the temperature of the fuel to rise beyond its melting point. In the early stages of the accident, operator could not determine the severity of the accident and the percentage of the reactor core damaged. The available data was based on the radiation exposure in the environment that was reported by the authorities. The aim of this paper is to determine the severity of the conditions in the reactor core based on the radiation doses measured in the environment. The method is performed by backward counting based on the measuring radiation exposure and radionuclides releases source term. The calculation was performed by using the PC-COSYMA code. The results showed that the core damage fraction at Dai-ichi Unit 1 was 70%, and the resulting individual effective dose in the exclusion area is 401 mSv, while the core damage fraction at Unit 2 was 30%, and the resulting individual effective dose was 9.1 mSv, while for Unit 3, the core damage fraction was 25% for an individual effective dose of 92.2 mSv. The differences between the results of the calculation for estimation of core damage proposed in this paper with the previously reported results is probably caused by the applied model for assessment, differences in postulations and assumptions, and the incompleteness of the input data. This difference could be reduced by performing calculations and simulations for more varied assumptions and postulations. (author)

Decision no. 2011-DC-0214 of the French nuclear safety authority from May 5, 2011, ordering CIS bio international company to proceed to a complementary safety evaluation of its basic nuclear facility in the eyes of the Fukushima Daiichi nuclear power plant accident

International Nuclear Information System (INIS)

2011-01-01

As a consequence of the accident of the Fukushima Daiichi nuclear power plant (Japan), the French Prime Minister entrusted the French nuclear safety authority (ASN) with the mission to carry out a safety analysis re-evaluation of the French nuclear facilities, and in particular the nuclear power plants. A decision has been addressed by the ASN to each nuclear operator with the specifications of this safety re-evaluation analysis and the list of facilities in concern. This document is the decision addressed to CIS bio international company, operator of the radiopharmaceuticals fabrication facility (INB 29) of Saclay (France). (J.S.)

Summary of atmospheric measurements and transport pathways of radioactive materials released by the Fukushima Daiichi Nuclear Power Plant accident

Energy Technology Data Exchange (ETDEWEB)

Tsuruta, Haruo; Nakajima, Teruyuki [Tokyo Univ., Atmosphere and Ocean Research Inst., Kashiwa, Chiba (Japan); Takigawa, Masayuki [Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa (Japan)

2012-11-15

After the Fukushima Daiichi Nuclear Power Plant (FD1NPP) accident, a continual monitoring of atmospheric radionuclides was independently carried out at several stations by different research institutions in the Kanto area south of Fukushima prefecture. No such measurements were made in the Fukushima area. Although the sampling methodology varied from one station to the next, the following results were found by the analysis of these data during March 13-31, 2011. High concentrations of {sup 131}I, {sup 134}Cs, and {sup 137}Cs in the atmosphere were observed in the first period (March 15-16, 2011) and the second period (March 20-23, 2011). According to a numerical simulation by an atmospheric transport model, these radionuclides were directly transported to the stations from the FD1NPP. The ratio of {sup 131}I to {sup 137}Cs in the atmosphere was around 10 in the first period and on March 20-21, while the ratio in the periods outside the first period and the March 20-21 was around 100. According to the measurements of gaseous {sup 131}I ({sup 131}I(g)) and particulate {sup 131}I ({sup 131}I(a)) which were performed separately at two stations, at least half of the total {sup 131}I (the sum of {sup 131}I(g) and {sup 131}I(a)) sampled was particulate {sup 131}I in the first and second periods, although {sup 131}I(a) was 20-40% of the total {sup 131}I in the periods outside the first and second periods. (author)

Radiological impact of TEPCO's Fukushima Dai-ichi Nuclear Power Plant accident on invertebrates in the coastal benthic food web.

Science.gov (United States)

Sohtome, Tadahiro; Wada, Toshihiro; Mizuno, Takuji; Nemoto, Yoshiharu; Igarashi, Satoshi; Nishimune, Atsushi; Aono, Tatsuo; Ito, Yukari; Kanda, Jota; Ishimaru, Takashi

2014-12-01

Radioactive cesium ((134)Cs and (137)Cs) concentrations in invertebrates of benthic food web (10 taxonomic classes with 46 identified families) collected from wide areas off Fukushima Prefecture (3-500 m depth) were inspected from July 2011, four months after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, to August 2013 to elucidate time-series trends among taxa and areas. Cesium-137 was detected in seven classes (77% of 592 specimens). Higher (137)Cs concentrations within detected data were often found in areas near or south of the FDNPP, which is consistent with the reported spatial distribution of (137)Cs concentrations in highly contaminated seawater and sediments after the FDNPP accident. Overall (137)Cs concentrations in invertebrates, the maxima of which (290 Bq kg(-1)-wet in the sea urchin Glyptocidaris crenularis) were lower than in many demersal fishes, had decreased exponentially with time, and exhibited taxon-specific decreasing trends. Concentrations in Bivalvia and Gastropoda decreased clearly with respective ecological half-lives of 188 d and 102 d. In contrast, decreasing trends in Malacostraca and Polychaeta were more gradual, with longer respective ecological half-lives of 208 d and 487 d. Echinoidea showed no consistent trend, presumably because of effects of contaminated sediments taken into their digestive tract. Comparison of (137)Cs concentrations in the invertebrates and those in seawater and sediments suggest that contaminated sediments are the major source of continuing contamination in benthic invertebrates, especially in Malacostraca and Polychaeta. Copyright © 2014 Elsevier Ltd. All rights reserved.

Radioactive Cs-137 discharge from Headwater Forested Catchment in Fukushima after Fukushima Dai-ichi Nuclear Power Plant Accident

Science.gov (United States)

Iwagami, S.; Onda, Y.; Tsujimura, M.; Sakakibara, K.; Konuma, R.

2015-12-01

Radiocesium migration from headwater forested catchment is important perception as output from the forest which is also input to the subsequent various land use and downstream rivers after Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. In this study, Cs-137 concentration of dissolved water, suspended sediment and coarse organic matter such as leaf and branch were monitored. Discharge amount of stream water, suspended sediment and coarse organic matter were measured to investigate the discharge amount of radiocesium and composition of radiocesium discharge form through the headwater stream. Observation were conducted at stream site in four headwater catchments in Yamakiya district, located ~35 km north west of FDNPP from June 2011 (suspended sediment and coarse organic matter: August 2012) to December 2014.The Cs-137 concentration of dissolved water was around 1Bq/l at June 2011. Then declined to 0.1 Bq/l at December 2011. And in December 2014, it declined to 0.01 Bq/l order. Declining trend of Cs-137 concentration in dissolved water was expressed in double exponential model. Also temporary increase was observed in dissolved Cs-137 during the rainfall event. The Cs-137 concentration of suspended sediment and coarse organic matter were 170-49000 Bq/kg and 350-14000 Bq/kg respectably. The Cs-137 concentration of suspended sediment showed good correlation with average deposition density of catchment. The effect of decontamination works appeared in declining of Cs-137 concentration in suspended sediment. Contribution rate of Cs-137 discharge by suspended sediment was 96-99% during a year. Total annual Cs-137 discharge from the catchment were 0.02-0.3% of the deposition.

The Fukushima Daiichi Nuclear Power Plant accident. How has the Geochemical Society of Japan been grappling with it?

International Nuclear Information System (INIS)

Ebihara, Mitsuru

2012-01-01

On March 11 in 2011, a great earthquake hit the eastern part of mainland Japan and triggered several gigantic tsunami waves, which destroyed the coastal areas in Tohoku and north Kanto districts facing the Pacific Ocean. The earthquake and a tsunami fatally damaged the Fukushima Daiichi Nuclear Power Plant (FDNPP) and took over the nuclear reactors. Eventually a large amount of radioactive materials was released into the environment. Radioactive nuclides were detected in a wide area including remote areas such as the Kanto district and metropolitan Tokyo. Some radioactive nuclides were detected in the United States and in some European countries, implying that radioactive materials released into the atmosphere and oceans were carried by global atmospheric and oceanic circulations all over the world. The Geochemical Society of Japan (GSJ) initiated several actions soon after the earthquake and the FDNPP accident. For instance, in response to the society's appeal, many GSJ members joined the project to map the distribution of several radioactive nuclides in soil samples in the Fukushima Prefecture. The members' contributions led to the creation of several distribution maps of radioactive nuclides, such as 134,137 Cs, 131 I, and 132 Te, trapped in soils in Fukushima. Another approach was to set the occasion for presenting the members' activities related to the FDNPP accident. For instance, the GSJ proposed to organize special sessions on research activities related to the FDNPP accident on the occasions of the 2011 Goldschmidt Conference and 2011 Annual Meeting of the GSJ. In this article, how the GSJ have been grappling with the PDNPP accident was chronologically described, especially from a viewpoint of an alliance with other organizations. (author)

Decontamination efficiencies of pot-type water purifiers for ¹³¹I, ¹³⁴Cs and ¹³⁷Cs in rainwater contaminated during Fukushima Daiichi nuclear disaster.

Directory of Open Access Journals (Sweden)

Shogo Higaki

Full Text Available Rainwater was contaminated by a large release of radionuclides into the environment during the Fukushima Daiichi nuclear disaster. It became a matter of concern for Japan when several water purification plants detected ¹³¹I contamination in the drinking water. In the present study, the decontamination efficiency of two easily obtainable commercial water purifiers were examined for rainwater contaminated with ¹³¹I, ¹³⁴Cs and ¹³⁷Cs. The water purifiers removed 94.2-97.8% of the ¹³¹I and 84.2-91.5% of the ¹³⁴Cs and ¹³⁷Cs after one filtration. Seven filtrations removed 98.2-99.6% of the ¹³¹I and over 98.0% of the ¹³⁴Cs and ¹³⁷Cs. From a practical perspective, over the fourth filtrations were not needed because of no significant improvements after the third filtration.

FY 1999 report on the results on analysis of protein functions; 1999 nendo tanpakushitsu kino kaiseki seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

This project is aimed at construction of the intellectual infrastructures for biotechnologies, in order to accelerate development of the Japanese technologies and activate their application to industries. Described herein are the FY 1999 results. These infrastructures are for functional analysis of protein which will be one of the key issues in genome analysis, and collection and analysis of biological information. This project includes a total of 9 research and development themes for four research categories: frequency analysis of gene expression (development of the gene expression profile database system for functional analysis of human genome, and analysis of the gene expression and protein functions by the ECA chip technology), function analysis by the biological model (high-performance analysis by the bio-project, database system for drug metabolizing enzymes, analysis of gene functions using mutant mice, and simple genome function analysis of murine individuals using the RNAi effect), protein expression (function validation of unknown human genes based on the useful biological model, and protein function analysis using multi-purpose destination vectors), and protein function prediction by the information science method. (NEDO)

Achievement report for fiscal 1982 on Sunshine Program. Coal energy; 1982 nendo sunshine keikaku seika hokokusho. Sekitan energy

Energy Technology Data Exchange (ETDEWEB)

NONE

1982-07-01

This research program consists of (1) the solid catalyst-aided reforming of various petroleum based oils and heavy coal oils into Solvolysis solvents and the secondary hydrogenolysis, (2) a search for pre-treatment for improvement on the sub-bituminous coal liquefaction yield, and (3) a search for measures for improvement on the brown coal liquefaction yield. Studied in this fiscal year are (1) the high-temperature short-contact time liquefaction of brown coal, (2) the role of catalyst support for selective upgrading of SRC (solvent refined coal), and (3) reforming of thermal melting feature of low rank coal by preliminary deashing at room temperature. In relation with Item (1), it is found that the dehydrogenation or reaction to carbonization of molecules involved in hydrogen donation is structure-sensitive but that thermolysis of coal is accelerated under high-temperature conditions to allow transfer hydrogen to contribute uniformly. It is deemed also that matching is excellent between hydrogen transfer and thermolysis, that the solvent dissolution level is elevated, and that the reaction short in duration inhibits consecutive polymerization reaction. These are supposed to be effective in improving on the liquefaction yield and in rendering heavy constituents lighter. In relation with Item (2), it is found that the experimentally manufactured catalysts are effective in reducing the weight of heavy constituents. In relation with Item (3), a carbonization reforming method is experimentally implemented in which the ash that affects carbonization is further removed by a pre-treatment at room temperature. (NEDO)

Outline of fiscal 1967 achievements in research on MHD power generation; 1967 nendo MHD hatsuden kenkyu seika gaiyo

Energy Technology Data Exchange (ETDEWEB)

NONE

1968-09-01

Compiled are the results of studies conducted in fiscal 1967 on MHD (magnetohydrodynamic) power generation. In the test operation and modification of a 1,000kW-class MHD power generator at the Electrical Research Laboratory, a test is conducted using Faraday-type electrodes. It is then found that this configuration results in a maximum output of approximately 700kW, which is less than expected. In the experimental construction at the Hitachi, Ltd., of a machine capable of a long-term operation, an MHD power generator is built for a continuous operation of 100 hours with an maximum output of 2kW, and a 110-hour power generation is successfully achieved with a maximum output of 1.9kW. In the research and development of heat exchangers, tests are conducted for a bulkhead type heat exchanger, heat accumulator type heat exchanger, molten slag type heat exchanger, and a gas/liquid 2-phase flow type heat exchanger. In the study of heat-resisting insulators, materials based on zirconate, magnesia, thoria, zirconia, etc., are tested. In addition, studies are conducted on electrode materials, superconductive electromagnets (small superconductive electromagnets for MHD power generators, turbine type helium liquefiers, superconductive wires for 70-kilogauss electromagnets, etc.), and thermal performance rating. (NEDO)

Outline of fiscal 1970 achievements in research on MHD power generation; 1970 nendo MHD hatsuden kenkyu seika gaiyo

Energy Technology Data Exchange (ETDEWEB)

NONE

1970-07-01

Compiled are the results of studies conducted in fiscal 1970 on MHD (magnetohydrodynamic) power generation. In the operation test and modification of the 1000kW-class MHD power generator, modification is carried out involving the combustion system, seed collecting method, and power generation channel, and reviews through experiments are conducted about the analysis and control of the boundary layer structure. In the operation test of the MHD power generator designed for prolonged operation, a test operation for resistance to heat and seeds continues more than 100 hours using a cold wall type power generation channel constituted of water cooled ceramics, and the ceramics are analyzed for failure and loss. Studies are also conducted involving MHD power generator heat exchangers, seed collecting methods, electrode materials for MHD power generators, heat-resistant materials for MHD power generators, thermal performance rating for MHD power plants, etc. In the research and development of superconductive electromagnets, superconductive electromagnets are developed and tested for 1000kW-class MHD power generators, and studies are conducted on turbine type helium liquefiers, superinsulated superconductive electromagnetic field generators, etc. (NEDO)

Achievement report for fiscal 1998. Multimedia system for the disabled; 1998 nendo seika hokokusho. Shogaisha taio multimedia system

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-05-01

Development has been made on the element technologies for a multimedia system for the disabled. In developing the non-visual graphical user interface (GUI) access system, a non-visual access system to enable the visually disabled to access a GUI system by utilizing sound and tactile devices was developed. In developing the three-dimensional sound utilizing information providing system, a system was developed, in which information on screen arrangement of the GUI in a personal computer is presented as spatial sound positions by using the three-dimensional sound control technology. The system can be operated non-visually using a mouse by controlling movements of a cursor. The current fiscal year has improved three-dimensional sound producing devices, three-dimensional sound interface, and how to handle their applications. User evaluations were also performed. Functions were expanded and improved in a system and an optical media reader that enable the visually disabled person to read printed papers by himself. Development was made also on a function to link the system with a total system. (NEDO)

Outline of fiscal 1969 achievements in research on MHD power generation; 1969 nendo MHD hatsuden kenkyu seika gaiyo

Energy Technology Data Exchange (ETDEWEB)

NONE

1969-07-01

Compiled are the results of studies conducted in fiscal 1969 on MHD (magnetohydrodynamic) power generation. In the operation test and modification of the 1,000kW-class MHD power generator, the operation test continues from the preceding fiscal year using high-temperature air as oxidant, and the growth of boundary layer in the channel is determined. In the operation test of the MHD power generator designed for prolonged operation, insulation walls, electrode materials, and structures capable of prolonged operation are developed and tested. In the research of MHD power generator heat exchangers, studies are made about the bulkhead type and heat accumulator types (stationary type, rotary type, and falling-grain type). In addition, studies are conducted about seed collecting methods, MHD power generator electrode materials, heat-resisting insulators, and thermal performance rating. In the research and development of superconductive electromagnets, studies are conducted about superconductive electromagnets for 1kW MHD power generators, ferromagnetic superconductive electromagnets for 1,000kW-class MHD power generators, 45-kilogauss col type superconductive electromagnets, turbine type helium liquefier, high current density col type superconductive electromagnets, superinsulated magnetic field generators, etc. (NEDO)

International Experts’ Meeting on Reactor and Spent Fuel Safety in the Light of the Accident at the Fukushima Daiichi Nuclear Power Plant. Presentations

International Nuclear Information System (INIS)

2012-01-01

The primary objectives of this International Experts’ Meeting (IEM) were: to analyse relevant technical aspects of reactor and spent nuclear fuel management safety and performance related to severe accidents; to review what is known to date about the accident at the Fukushima Daiichi nuclear power plant in order to understand more fully its root causes; and to share the lessons learned from the accident. The meeting identified the necessary priorities for further actions in these areas in different power reactor types, focusing in particular on boiling water reactors (BWRs) and pressurized water reactors (PWRs). The meeting provided a forum for discussions and exchange of information among technical experts from Member States on reactor and spent nuclear fuel safety and performance under severe conditions. The meeting was of particular interest to technical experts from utilities, research and design organizations, regulatory bodies, manufacturing and service companies and other stakeholders. In particular, the objectives of the meeting was to: • Identify and analyse reactor and spent nuclear fuel safety and performance issues; • Consider the design, engineering and analysis of current and new systems for accident prevention and mitigation; • Exchange information on national assessments of reactor and spent nuclear fuel safety and performance; and • Identify potential priority areas for research and development, technology development and management

Sensitivity of the modelled deposition of Caesium-137 from the Fukushima Dai-ichi nuclear power plant to the wet deposition parameterisation in NAME

International Nuclear Information System (INIS)

Leadbetter, Susan J.; Hort, Matthew C.; Jones, Andrew R.; Webster, Helen N.; Draxler, Roland R.

2015-01-01

This paper describes an investigation into the impact of different meteorological data sets and different wet scavenging coefficients on the model predictions of radionuclide deposits following the accident at the Fukushima Dai-ichi nuclear power plant in March 2011. Three separate operational meteorological data sets, the UK Met Office global meteorology, the ECMWF global meteorology and the Japan Meteorological Agency (JMA) mesoscale meteorology as well as radar rainfall analyses from JMA were all used as inputs to the UK Met Office's dispersion model NAME (the Numerical Atmospheric-dispersion Modelling Environment). The model predictions of Caesium-137 deposits based on these meteorological models all showed good agreement with observations of deposits made in eastern Japan with correlation coefficients ranging from 0.44 to 0.80. Unexpectedly the NAME run using radar rainfall data had a lower correlation coefficient (R = 0.66), when compared to observations, than the run using the JMA mesoscale model rainfall (R = 0.76) or the run using ECMWF met data (R = 0.80). Additionally the impact of modifying the wet scavenging coefficients used in the parameterisation of wet deposition was investigated. The results showed that modifying the scavenging parameters had a similar impact to modifying the driving meteorology on the rank calculated from comparing the modelled and observed deposition

Detailed deposition density maps constructed by large-scale soil sampling for gamma-ray emitting radioactive nuclides from the Fukushima Dai-ichi Nuclear Power Plant accident.

Science.gov (United States)

Saito, Kimiaki; Tanihata, Isao; Fujiwara, Mamoru; Saito, Takashi; Shimoura, Susumu; Otsuka, Takaharu; Onda, Yuichi; Hoshi, Masaharu; Ikeuchi, Yoshihiro; Takahashi, Fumiaki; Kinouchi, Nobuyuki; Saegusa, Jun; Seki, Akiyuki; Takemiya, Hiroshi; Shibata, Tokushi

2015-01-01

Soil deposition density maps of gamma-ray emitting radioactive nuclides from the Fukushima Dai-ichi Nuclear Power Plant (NPP) accident were constructed on the basis of results from large-scale soil sampling. In total 10,915 soil samples were collected at 2168 locations. Gamma rays emitted from the samples were measured by Ge detectors and analyzed using a reliable unified method. The determined radioactivity was corrected to that of June 14, 2011 by considering the intrinsic decay constant of each nuclide. Finally the deposition maps were created for (134)Cs, (137)Cs, (131)I, (129m)Te and (110m)Ag. The radioactivity ratio of (134)Cs-(137)Cs was almost constant at 0.91 regardless of the locations of soil sampling. The radioactivity ratios of (131)I and (129m)Te-(137)Cs were relatively high in the regions south of the Fukushima NPP site. Effective doses for 50 y after the accident were evaluated for external and inhalation exposures due to the observed radioactive nuclides. The radiation doses from radioactive cesium were found to be much higher than those from the other radioactive nuclides. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Comparison of radiocesium concentration changes in leguminous and non-leguminous herbaceous plants observed after the Fukushima Dai-ichi Nuclear Power Plant accident.

Science.gov (United States)

Uchida, Shigeo; Tagami, Keiko

2018-06-01

Transfer of radiocesium from soil to crops is an important pathway for human intake. In the period from one to two years after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, food monitoring results showed that radiocesium concentrations in soybean (a legume) were higher than those in other annual agricultural crops; in these crops, root uptake is the major pathway of radiocesium from soil to plant. However, it was not clear whether or not leguminous and non-leguminous herbaceous plants have different Cs uptake abilities from the same soil because crop sample collection fields were different. In this study, therefore, we compared the concentrations of 137 Cs in seven herbaceous plant species including two leguminous plants (Trifolium pratense L. and Vicia sativa L.) collected in 2012-2016 from the same sampling field in Chiba, Japan that had been affected by the FDNPP accident fallout. Among these species, Petasites japonicus (Siebold & Zucc.) Maxim. showed the highest 137 Cs concentration in 2012-2016. The correlation factor between all concentration data for 137 Cs and those for 40 K in these seven plants was R = 0.54 (p plants did not differ significantly, but 137 Cs data in the Poaceae family plants were significantly lower than those in T. pratense (p plants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cooperation between National Defense Medical College and Fukushima Medical University in thyroid ultrasound examination after the Fukushima Daiichi nuclear power plant disaster

International Nuclear Information System (INIS)

Yamamoto, Yoritsuna; Fujita, Masanori; Tachibana, Shoich; Morita, Koji; Hamano, Kunihisa; Hamada, Koji; Uchida, Kosuke; Tanaka, Yuji

2013-01-01

Fukushima Daiichi Nuclear Power Plant was utterly destroyed by The Great East Japan Earthquake which happened on March 11, 2011, and followed by radioactive contamination to the surrounding areas. Based on the known radioactive iodine ("1"3"1I) which led to thyroid cancer in children after the Chernobyl nuclear power plant disaster in 1986, children living in Fukushima should be carefully observed for the development of thyroid cancer. Fukushima Prefecture and Fukushima Medical University started ''Fukushima Health Management Survey'' in May 2011, which includes screening for thyroid cancer by ultrasonography (Thyroid Ultrasound Examination). Thyroid Ultrasound Examination would cover roughly 360,000 residents aged 0 to 18 years of age at the time of the nuclear disaster. The initial screening is to be performed within the first three years after the accident, followed by complete thyroid examinations from 2014 onwards, and the residents will be monitored regularly thereafter. As Thyroid Ultrasound Examination is being mainly performed by medical staff at Fukushima Medical University, there is insufficient manpower to handle the large number of potential examinees. Thus, specialists of thyroid diseases from all over Japan have begun to support this examination. Six endocrinologists including the authors belonging to the National Defense Medical College are cooperating in part of this examination. This paper briefly reports the outline of Thyroid Ultrasound Examination and our cooperation. (author)

Assessment of the Annual Additional Effective Doses amongst Minamisoma Children during the Second Year after the Fukushima Daiichi Nuclear Power Plant Disaster.

Science.gov (United States)

Tsubokura, Masaharu; Kato, Shigeaki; Morita, Tomohiro; Nomura, Shuhei; Kami, Masahiro; Sakaihara, Kikugoro; Hanai, Tatsuo; Oikawa, Tomoyoshi; Kanazawa, Yukio

2015-01-01

An assessment of the external and internal radiation exposure levels, which includes calculation of effective doses from chronic radiation exposure and assessment of long-term radiation-related health risks, has become mandatory for residents living near the nuclear power plant in Fukushima, Japan. Data for all primary and secondary children in Minamisoma who participated in both external and internal screening programs were employed to assess the annual additional effective dose acquired due to the Fukushima Daiichi nuclear power plant disaster. In total, 881 children took part in both internal and external radiation exposure screening programs between 1st April 2012 to 31st March 2013. The level of additional effective doses ranged from 0.025 to 3.49 mSv/year with the median of 0.70 mSv/year. While 99.7% of the children (n = 878) were not detected with internal contamination, 90.3% of the additional effective doses was the result of external radiation exposure. This finding is relatively consistent with the doses estimated by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The present study showed that the level of annual additional effective doses among children in Minamisoma has been low, even after the inter-individual differences were taken into account. The dose from internal radiation exposure was negligible presumably due to the success of contaminated food control.

Uncertainty analysis of atmospheric deposition simulation of radiocesium and radioiodine from Fukushima Daiichi Nuclear Power Plant

Science.gov (United States)

Morino, Yu; Ohara, Toshimasa; Yumimoto, Keiya

2014-05-01

Chemical transport models (CTM) played key roles in understanding the atmospheric behaviors and deposition patterns of radioactive materials emitted from the Fukushima Daiichi nuclear power plant (FDNPP) after the nuclear accident that accompanied the great Tohoku earthquake and tsunami on 11 March 2011. In this study, we assessed uncertainties of atmospheric simulation by comparing observed and simulated deposition of radiocesium (137Cs) and radioiodine (131I). Airborne monitoring survey data were used to assess the model performance of 137Cs deposition patterns. We found that simulation using emissions estimated with a regional-scale (~500 km) CTM better reproduced the observed 137Cs deposition pattern in eastern Japan than simulation using emissions estimated with local-scale (~50 km) or global-scale CTM. In addition, we estimated the emission amount of 137Cs from FDNPP by combining a CTM, a priori source term, and observed deposition data. This is the first use of airborne survey data of 137Cs deposition (more than 16,000 data points) as the observational constraints in inverse modeling. The model simulation driven by a posteriori source term achieved better agreements with 137Cs depositions measured by aircraft survey and at in-situ stations over eastern Japan. Wet deposition module was also evaluated. Simulation using a process-based wet deposition module reproduced the observations well, whereas simulation using scavenging coefficients showed large uncertainties associated with empirical parameters. The best-available simulation reproduced the observed 137Cs deposition rates in high-deposition areas (≥10 kBq m-2) within one order of magnitude. Recently, 131I deposition map was released and helped to evaluate model performance of 131I deposition patterns. Observed 131I/137Cs deposition ratio is higher in areas southwest of FDNPP than northwest of FDNPP, and this behavior was roughly reproduced by a CTM if we assume that released 131I is more in gas phase

Decision no. 2011-DC-0223 of the French nuclear safety authority from May 5, 2011, ordering the MELOX SA company to proceed to a complementary safety evaluation of some of its basic nuclear facilities in the eyes of the Fukushima Daiichi nuclear power plant accident

International Nuclear Information System (INIS)

2011-01-01

As a consequence of the accident of the Fukushima Daiichi nuclear power plant (Japan), the French Prime Minister entrusted the French nuclear safety authority (ASN) with the mission to carry out a safety analysis re-evaluation of the French nuclear facilities, and in particular the nuclear power plants. A decision has been addressed by the ASN to each nuclear operator with the specifications of this safety re-evaluation analysis and the list of facilities in concern. This document is the decision addressed to MELOX SA company, operator of the Melox MOX fuel fabrication plant of Marcoule (France). (J.S.)

Decision no. 2011-DC-0218 of the French nuclear safety authority from May 5, 2011, ordering the EURODIF SA company to proceed to a complementary safety evaluation of some of its basic nuclear facilities in the eyes of the Fukushima Daiichi nuclear power plant accident

International Nuclear Information System (INIS)

2011-01-01

As a consequence of the accident of the Fukushima Daiichi nuclear power plant (Japan), the French Prime Minister entrusted the French nuclear safety authority (ASN) with the mission to carry out a safety analysis re-evaluation of the French nuclear facilities, and in particular the nuclear power plants. A decision has been addressed by the ASN to each nuclear operator with the specifications of this safety re-evaluation analysis and the list of facilities in concern. This document is the decision addressed to the EURODIF SA company, operator of the George Besse I uranium enrichment plant of the Tricastin site (France). (J.S.)

Decision no. 2011-DC-0219 of the French nuclear safety authority from May 5, 2011, ordering the SOCATRI company to proceed to a complementary safety evaluation of some of its basic nuclear facilities in the eyes of the Fukushima Daiichi nuclear power plant accident

International Nuclear Information System (INIS)

2011-01-01

As a consequence of the accident of the Fukushima Daiichi nuclear power plant (Japan), the French Prime Minister entrusted the French nuclear safety authority (ASN) with the mission to carry out a safety analysis re-evaluation of the French nuclear facilities, and in particular the nuclear power plants. A decision has been addressed by the ASN to each nuclear operator with the specifications of this safety re-evaluation analysis and the list of facilities in concern. This document is the decision addressed to the SOCATRI company, operator of the nuclear dismantling and waste processing plants of the Tricastin site (France). (J.S.)

Depth profiles of radioactive cesium and iodine released from the Fukushima Daiichi nuclear power plant in different agricultural fields and forests

International Nuclear Information System (INIS)

Ohno, Takeshi; Muramatsu, Yasuyuki; Oda, Kazumasa; Inagawa, Naoya; Ogawa, Hiromu; Yamazaki, Atsuko; Toyama, Chiaki; Miura, Yoshinori; Sato, Mutsuto

2012-01-01

In order to understand the behavior of radionuclides released from the Fukushima Daiichi nuclear power plant, the depth distributions of radiocesium and radioiodine were investigated in a wheat field, a rice paddy, an orchard, and a cedar forest in Koriyama, Fukushima Prefecture. Our results demonstrate that, following the nuclear power plant disaster, more than 90% of the radionuclides were distributed in the upper 6 cm of the soil column in the wheat field and within 4 cm of the surface in the rice paddy, orchard, and cedar forest. According to the measurement of radionuclides in the three adjacent agricultural fields, the variation of deposition densities in the wheat field was smaller than that of the orchard and rice paddy, suggesting that the low permeability of the orchard and paddy soils may cause horizontal migration of radionuclides during the initial deposition. This result indicates that the deposition densities in the wheat field should be appropriate for estimating the amount of fallout in the area. The deposition densities of 134 Cs, 137 Cs, and 131 I in this area were estimated to be 512 ± 76 (SD, n = 5), 522 ± 80 (SD, n = 5), and 608 ± 79 (SD, n = 5) kBq/m 2 (decay corrected to April 1, 2011), respectively. A comparison of the deposition density between the wheat field and the cedar forest suggests that more than half of the radionuclides are distributed in the tree canopies of the evergreen forestland. (author)

Report of the results of the fiscal 1997 regional consortium R and D project. Regional consortium field / R and D on process adaptive type flexible robot technology (first fiscal year); 1997 nendo chiiki consortium kenkyu kaihatsu jigyo. Chiiki consortium bun`ya / kotei tekiogata flexible robot gijutsu ni kansuru kaihatsu (daiichi nendo) seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-03-01

For the purpose of establishing robot technology required for the construction of a highly functional automation line with flexibility, the R and D were conducted. At Kumamoto University, a model following type power control system was studied into which polynominal trajectory formation algorithm was integrated. Also studied was damping control of robot arms in a disturbance environment. The following were further carried out: experimental verification (HIRATA Corporation) of the application of power control and intelligent control to transportation equipment production line, experimental verification (SAKURAI SEIGI Co. Ltd.) of the application of power control and intelligent control to semiconductor testing equipment, R and D (OMRON Corporation) of high accuracy force sensing and positioning system, research (Kumamoto Technopolis Foundation) on flexible arms/hands suitable for cooperative control, sensor-based skill (Electrotechnical Laboratory), research (Kyushu National Industrial Research Institute) on tactual system and tactual sensing, etc. 20 refs., 86 figs., 14 tabs.

Municipalities' opinions about decontamination in special decontamination area. Records from four and a half years after the Fukushima Daiichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Kawasaki, Kota

2016-01-01

This study discusses opinions of 11 municipalities in Fukushima Prefecture designated as Special Decontamination Area as of the end of September 2015, about four and a half years afters the Fukushima Daiichi Nuclear Power Plant accident. This study shows that (1) more than half of the municipalities recognize that decontamination activities of the national government which is responsible for decontamination in Special Decontamination Area are inadequate, (2) most municipalities recognize that residents cannot live their lives with a sense of safety and security unless air radiation dose is reduced to the level before the accident or less than 0.23 μSv/h, (3) many municipalities recognize that residents will not be able to live their lives with a sense of safety and security even if the national government implements decontamination, (4) municipalities points out 'decontamination of forests or rivers and reconsideration of decontamination methods of forests or rivers', 'securement and maintenance of temporary storage site' and 'setting forth a numeric target concerning decontamination and implementation of additional decontamination after the first decontamination' as issues for the promotion of decontamination, and (5) all the municipalities recognize that that there are a lot of problems concerning the installation of interim storage facilities by the national government. (author)

An overview of current knowledge concerning the health and environmental consequences of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident.

Science.gov (United States)

Aliyu, Abubakar Sadiq; Evangeliou, Nikolaos; Mousseau, Timothy Alexander; Wu, Junwen; Ramli, Ahmad Termizi

2015-12-01

Since 2011, the scientific community has worked to identify the exact transport and deposition patterns of radionuclides released from the accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Japan. Nevertheless, there still remain many unknowns concerning the health and environmental impacts of these radionuclides. The present paper reviews the current understanding of the FDNPP accident with respect to interactions of the released radionuclides with the environment and impacts on human and non-human biota. Here, we scrutinize existing literature and combine and interpret observations and modeling assessments derived after Fukushima. Finally, we discuss the behavior and applications of radionuclides that might be used as tracers of environmental processes. This review focuses on (137)Cs and (131)I releases derived from Fukushima. Published estimates suggest total release amounts of 12-36.7PBq of (137)Cs and 150-160PBq of (131)I. Maximum estimated human mortality due to the Fukushima nuclear accident is 10,000 (due to all causes) and the maximum estimates for lifetime cancer mortality and morbidity are 1500 and 1800, respectively. Studies of plants and animals in the forests of Fukushima have recorded a range of physiological, developmental, morphological, and behavioral consequences of exposure to radioactivity. Some of the effects observed in the exposed populations include the following: hematological aberrations in Fukushima monkeys; genetic, developmental and morphological aberrations in a butterfly; declines in abundances of birds, butterflies and cicadas; aberrant growth forms in trees; and morphological abnormalities in aphids. These findings are discussed from the perspective of conservation biology. Copyright © 2015 Elsevier Ltd. All rights reserved.

Pregnancy and birth survey after the Great East Japan Earthquake and Fukushima Daiichi Nuclear Power Plant accident in Fukushima prefecture.

Science.gov (United States)

Fujimori, Keiya; Kyozuka, Hyo; Yasuda, Shun; Goto, Aya; Yasumura, Seiji; Ota, Misao; Ohtsuru, Akira; Nomura, Yasuhisa; Hata, Kenichi; Suzuki, Kouta; Nakai, Akihito; Sato, Mieko; Matsui, Shiro; Nakano, Kyoko; Abe, Masafumi

2014-01-01

On 11 March 2011, the Great East Japan Earthquake followed by a powerful tsunami hit the Pacific Coast of Northeast Japan and damaged Tokyo Electric Power Company's Fukushima Daiichi Nuclear Power Plant, causing a radiation hazard in Fukushima Prefecture. The objective of this report is to describe some results of a questionnaire-based pregnancy and birth survey conducted by the Radiation Medical Science Center for the Fukushima Health Management Survey. Questionnaires were sent to women who received maternal and child health handbooks from municipal officers in Fukushima Prefecture between 1 August 2010 and 31 July 2011, with the aim of reaching those who were pregnant at the time of the disaster. Mailing began 18 January 2012. Data were analyzed separately for six geographic areas in Fukushima Prefecture. The total number of women meeting survey criteria was 15,972. The number of responses received to date is 9,298 (58.2%). Data from 8602 respondents were analyzed after excluding 634 invalid responses and 5 induced and 57 spontaneous abortions (less than 22 gestational weeks). The incidences of stillbirth (over 22 completed gestational weeks), preterm birth, low birth weight and congenital anomalies were 0.25%, 4.4%, 8.7% and 2.72%, respectively. These incidences are similar to recent averages elsewhere in Japan. Considering the pregnancy and birth survey data in aggregate, our disaster seemed to provoke no significant adverse outcomes over the whole of Fukushima prefecture. But post-disaster prenatal care and support intended for patients' safety and security should be coupled with ongoing surveillance and rigorous data analysis.

Feasibility study on phyto-remediation techniques for soil contaminated by the Fukushima Dai-Ichi nuclear power plant accident

Energy Technology Data Exchange (ETDEWEB)

Yuu Ishimori; Akihiro Sakoda [Japan Atomic Energy Agency, Kagamino, Okayama (Japan); Mina Yamada; Yuko Makino; Satoshi Yamada; Hideyasu Fujiyama [Tottori University, Tottori, Tottori (Japan)

2013-07-01

Tottori University and the Japan Atomic Energy Agency carried out jointly the feasibility study on phyto-remediation techniques, which apply to soil contaminated by the TEPCO's Fukushima Dai-ichi NPP accident. This paper illustrates the results from experimental investigations. Experimental investigations include both water-culture tests and field tests. Several plants, mainly halophytes that can specifically absorb more Na than K, and others like sunflower demonstrated for other domestic large-scale tests, were water-cultured and examined for screening. Easily cultivated and harvested plants without harmful effects on subsequent cultivation were also considered. New Zealand spinach was selected as a candidate for demonstrations in fields. The field tests were carried out at two sites of different agricultural types in Minami-soma, Fukushima prefecture. Concentration of {sup 137}Cs in soil is about 4.5 Bq/g-dry as the average of 10 cm depth. The aims of the field tests are to confirm absorption ability and environmental adaptation of the test plants and to document the cost and performance of projects. In conclusion, the absorption of {sup 137}Cs activity per unit area (Bq/m{sup 2}) by New Zealand spinach could be approximately 0.5%. To achieve an effective result in removal of {sup 137}Cs from soil in around a decade, it is required to find the plant which has ten or more times higher absorption capacity than New Zealand spinach. From the consistency of both results in water-culture and field tests, the water-culture test can be valid for screening. In addition, applicable sites will be limited to fields which are too steep or too narrow to use mechanical diggers, and which are free from any restrictions to enter. (authors)

Distribution of artificial radionuclides in abandoned cattle in the evacuation zone of the Fukushima Daiichi nuclear power plant.

Directory of Open Access Journals (Sweden)

Tomokazu Fukuda

Full Text Available The Fukushima Daiichi Nuclear Power Plant (FNPP accident released large amounts of radioactive substances into the environment. In order to provide basic information for biokinetics of radionuclides and for dose assessment of internal exposure brought by the FNPP accident, we determined the activity concentration of radionuclides in the organs of 79 cattle within a 20-km radius around the FNPP. In all the specimens examined, deposition of Cesium-134 ((134Cs, half-life: 2.065 y and (137Cs (30.07 y was observed. Furthermore, organ-specific deposition of radionuclides with relatively short half-lives was detected, such as silver-110m ((110mAg, 249.8 d in the liver and tellurium-129m ((129mTe, 33.6 d in the kidney. Regression analysis showed a linear correlation between the radiocesium activity concentration in whole peripheral blood (PB and that in each organ. The resulting slopes were organ dependent with the maximum value of 21.3 being obtained for skeletal muscles (R(2 = 0.83, standard error (SE = 0.76. Thus, the activity concentration of (134 Cs and (137Cs in an organ can be estimated from that in PB. The level of radioactive cesium in the organs of fetus and infants were 1.19-fold (R(2 = 0.62, SE = 0.12, and 1.51-fold (R(2 = 0.70, SE = 0.09 higher than that of the corresponding maternal organ, respectively. Furthermore, radiocesium activity concentration in organs was found to be dependent on the feeding conditions and the geographic location of the cattle. This study is the first to reveal the detailed systemic distribution of radionuclides in cattle attributed to the FNPP accident.

First Successful Pre-Distribution of Stable Iodine Tablets Under Japan's New Policy After the Fukushima Daiichi Nuclear Accident.

Science.gov (United States)

Ojino, Mayo; Yoshida, Sumito; Nagata, Takashi; Ishii, Masami; Akashi, Makoto

2017-06-01

Stable iodine tablets are effective in reducing internal exposure to radioactive iodine, which poses a risk for thyroid cancer and other conditions. After the Fukushima Daiichi nuclear power plant accident, the Japanese government shifted its policy on stable iodine tablet distribution from "after-the-fact" to "before-the-fact" and instructed local governments to pre-distribute stable iodine tablets to residents living within a 5-km radius of nuclear facilities. The nation's first pre-distribution of stable iodine tablets was carried out in June and July of 2014 in Kagoshima Prefecture. Health surveys were conducted so that the medication would not be handed out to people with the possibility of side effects. Of the 4715 inhabitants in the area, 132 were found to require a physician's judgment, mostly to exclude risks of side effects. This was considered important to prevent the misuse of the tablets in the event of a disaster. The importance of collective and individualized risk communication between physicians and inhabitants at the community health level was apparent through this study. Involvement of physicians through the regional Sendai City Medical Association was an important component of the pre-distribution. Physicians of the Sendai City Medical Association were successfully educated by using the Guidebook on Distributing and Administering Stable Iodine Tablets prepared by the Japan Medical Association and Japan Medical Association Research Institute with the collaboration of the National Institute of Radiological Sciences and the Japanese government. Thus, the physicians managed to make decisions on the dispensing of stable iodine tablets according to the health conditions of the inhabitants. All physicians nationwide should be provided continuing medical education on stable iodine tablets. (Disaster Med Public Health Preparedness. 2017;11:365-369).

Lessons learned from Fukushima Daiichi nuclear power plant accident: efficient education items of radiation safety for general public

International Nuclear Information System (INIS)

Ohno, K.; Endo, K.

2015-01-01

The Fukushima Daiichi nuclear power plant (FNP-1) accident, while as tragic as the tsunami, was a man-made disaster created by the ignorance of the effects of radiation and radioactive materials. Therefore, it is important that all specialists in radiation protection in medicine sympathize with the anxiety of the general public regarding the harmful effects of radiation and advise people accordingly. All questions and answers were collected related to inquiries from the general public that were posted to reliable web sites, including those of the government and radiation-related organizations, from March 2011 to November 2012. The questions were summarized and classified by similarity of content. (1) The total number of questions is 372. The content was broadly classified into three categories: inquiries for radiation-related knowledge and about health effects and foods. The questions asked to obtain radiation-related knowledge were the most common, accounting for 38 %. Thirty-six percentage of the questions were related to health effects, and 26 % involved foods, whereas 18 % of the questions were related to children and pregnancy. (2) The change over time was investigated in 290 questions for which the time of inquiry was known. Directly after the earthquake, the questions were primarily from people seeking radiation-related knowledge. Later, questions related to health effects increased. The anxiety experienced by residents following the nuclear accident was caused primarily by insufficient knowledge related to radiation, concerns about health effects and uncertainties about food and water safety. The development of educational materials focusing on such content will be important for risk communication with the general public in countries with nuclear power plants. Physicians and medical physicist should possess the ability to respond to questions such as these and should continue with medical examinations and treatments in a safe and appropriate manner

137Cs vertical migration in a deciduous forest soil following the Fukushima Dai-ichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Nakanishi, Takahiro; Matsunaga, Takeshi; Koarashi, Jun; Atarashi-Andoh, Mariko

2014-01-01

The large amount of 137 Cs deposited on the forest floor because of the Fukushima Dai-ichi Nuclear Power Plant accident represents a major potential long-term source for mobile 137 Cs. To investigate 137 Cs mobility in forest soils, we investigated the vertical migration of 137 Cs through seepage water, using a lysimetric method. The study was conducted in a deciduous forest soil over a period spanning 2 month to 2 y after the Fukushima nuclear accident. Our observations demonstrated that the major part of 137 Cs in the litter layer moved into the mineral soil within one year after the accident. On the other hand, the topsoil prevented migration of 137 Cs, and only 2% of 137 Cs in the leachate from litter and humus layer penetrated below a 10 cm depth. The annual migration below a 10 cm depth accounted for 0.1% of the total 137 Cs inventory. Therefore, the migration of 137 Cs by seepage water comprised only a very small part of the total 137 Cs inventory in the mineral soil, which was undetectable from the vertical distribution of 137 Cs in the soil profile. In the present and immediate future, most of the 137 Cs deposited on the forest floor will probably remain in the topsoil successively, although a small but certain amount of bioavailable 137 Cs exists in forest surface soil. -- Highlights: • Lysimeter captured 137 Cs mobility in a forest soil after the Fukushima accident. • Major part of 137 Cs in the litter layer moved into the mineral soil within a year. • Litter-leachate 137 Cs was predominantly adsorbed within the topsoil. • The annual migration below a 10 cm depth was 0.1% of the total 137 Cs inventory

Extractability of radiocesium from processed green tea leaves with hot water. The first emergent tea leaves harvested after the TEPCO's Fukushima Daiichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Tagami, K.; Uchida, S.; Ishii, N.

2012-01-01

In some tea tree planting areas within 300 km from the TEPCO's Fukushima Daiichi Nuclear Power Plant (FNPP), it was found that newly emerged tea plant leaves for green tea contained two radiocesium species (cesium-134 and cesium-137). In this study, using processed green tea leaves for drinking, extraction ratios of radiocesium under several brew conditions were observed. When 90 deg C water was used, 50-70% of radiocesium was extracted into the water, while 54-60% of radiocesium was extracted with 60 deg C water. A part of radiocesium would be removed from leaves if the leaves were washed with 20 and 60 deg C water before brewing, and the efficiencies were 11 and 32%, respectively. Newly emerged camellia leaves were used to simulate the radiocesium removal ratio from raw tea leaves by washing and boiling; radioactivity concentration was decreased to 60% of the original concentration with washing and 10 min boiling. From these results, it was found that almost half of the radiocesium would not be removed from raw or processed tea leaves. The values obtained in the present study could be used for internal radiation dose estimation from tea leaves. (author)

Basic concept of the nuclear emergency preparedness and response in Japan after the accident of the Fukushima Dai-ichi Nuclear Power Station. The plain explanation for regional officials and emergency workers

International Nuclear Information System (INIS)

Sato, Sohei; Yamamoto, Kazuya

2013-07-01

After the accident of TEPCO's Fukushima Dai-ichi Nuclear Power Station occurred on March 11, 2011, actions for controlling the accident and protective actions for the residents like evacuation were taken. In parallel with this, it has been developed to reform the nuclear regulatory systems and the emergency preparedness and response systems in Japan. Especially the Nuclear Regulation Authority's Nuclear Emergency Preparedness and Response Guidelines were adopted with the introducing the basic concepts and the criteria on the basis of the IAEA's safety standards and differed greatly from the prior guidelines. Thus the arrangement of emergency response systems, resources and the operational procedures will be developed complying with according to the guidelines in municipalities around the nuclear power station sites. This work attempts to provide a plain explanation as possible for the regional officials and emergency workers about the basic concepts of the new guidelines. (author)

Effects of indoor and outdoor cultivation conditions on 137 Cs concentrations in cultivated mushrooms produced after the Fukushima Daiichi Nuclear Power Plant accident.

Science.gov (United States)

Tagami, Keiko; Uchida, Shigeo; Ishii, Nobuyoshi

2017-01-01

Radiocesium ( 134 Cs and 137 Cs) in mushrooms has been a matter of public concern after the accident at Fukushima Daiichi Nuclear Power Plant. To minimize the internal dose by ingestion of cultivated mushrooms, the Japanese government set a guideline level with respect to the radiocesium concentration in bed-logs and mushroom beds; however, the effects of indoor and outdoor cultivation methods on radiocesium concentrations in cultivated mushrooms were not clear. The effects of indoor and outdoor cultivation on the radiocesium concentrations in mushroom were examined using published food monitoring data. 137 Cs concentration data in Lentinula edodes from the Aizu area in Fukushima Prefecture and seven prefectures outside Fukushima were used for the analysis. No statistically significant 137 Cs concentration differences were found between these two cultivation methods. Using detected 137 Cs data in shiitake, the geometric means from each prefecture were less than one-quarter of the standard limit (100 Bq kg -1 ) for total radiocesium under both cultivation conditions. It was suspected that re-suspended radiocesium might have been taken up by mushrooms or that radiocesium might have been absorbed into the mushrooms from the soil in the outdoor cultures. However, neither effect was significant for cultivated mushrooms in the areas examined. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

135Cs activity and 135Cs/137Cs atom ratio in environmental samples before and after the Fukushima Daiichi Nuclear Power Plant accident.

Science.gov (United States)

Yang, Guosheng; Tazoe, Hirofumi; Yamada, Masatoshi

2016-04-07

(135)Cs/(137)Cs is a potential tracer for radiocesium source identification. However, due to the challenge to measure (135)Cs, there were no (135)Cs data available for Japanese environmental samples before the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. It was only 3 years after the accident that limited (135)Cs values could be measured in heavily contaminated environmental samples. In the present study, activities of (134)Cs, (135)Cs, and (137)Cs, along with their ratios in 67 soil and plant samples heavily and lightly contaminated by the FDNPP accident were measured by combining γ spectrometry with ICP-MS/MS. The arithmetic means of the (134)Cs/(137)Cs activity ratio (1.033 ± 0.006) and (135)Cs/(137)Cs atom ratio (0.334 ± 0.005) (decay corrected to March 11, 2011), from old leaves of plants collected immediately after the FDNPP accident, were confirmed to represent the FDNPP derived radiocesium signature. Subsequently, for the first time, trace (135)Cs amounts before the FDNPP accident were deduced according to the contribution of global and FDNPP accident-derived fallout. Apart from two soil samples with a tiny global fallout contribution, contributions of global fallout radiocesium in other soil samples were observed to be 0.338%-52.6%. The obtained (135)Cs/(137)Cs database will be useful for its application as a geochemical tracer in the future.

Sedimentation and remobilization of radiocesium in the coastal area of Ibaraki, 70 km south of the Fukushima Dai-ichi Nuclear Power Plant.

Science.gov (United States)

Otosaka, Shigeyoshi; Kobayashi, Takuya

2013-07-01

Sedimentation and remobilization processes of radiocesium were investigated from time-series observations at nine stations in the coastal area of Ibaraki, 70-110 km south of the Fukushima Dai-ichi Nuclear Power Plant (1FNPP). Sediment samples were collected four times between June 2011 and January 2012, and concentrations of radiocesium as well as sediment properties such as grain size and elemental compositions were analyzed. Cumulative inventory of (137)Cs in sediment (0-10 cm) ranged between 4 × 10(3) and 3 × 10(4) Bq/m(2) as of January 2012. This amount was generally higher at stations nearer 1FNPP and has remained at the same level since August 2011. From these results, it can be inferred that dissolved radiocesium advected southward from the region adjacent to the 1FNPP and was deposited to the sediment of the study area in the early stage after the accident. The incorporation of radiocesium into sediments was almost irreversible, and higher concentrations of (137)Cs were obtained from the finer-grained fraction of sediments. In the northern offshore stations, resuspension of the fine-grained sediments formed a high-turbidity layer 10-20 m above the seabed. These results indicate that radiocesium-enriched fine particles were transported from the coast to offshore regions through the bottom high-turbidity layer.

Isotopic signature and nano-texture of cesium-rich micro-particles: Release of uranium and fission products from the Fukushima Daiichi Nuclear Power Plant.

Science.gov (United States)

Imoto, Junpei; Ochiai, Asumi; Furuki, Genki; Suetake, Mizuki; Ikehara, Ryohei; Horie, Kenji; Takehara, Mami; Yamasaki, Shinya; Nanba, Kenji; Ohnuki, Toshihiko; Law, Gareth T W; Grambow, Bernd; Ewing, Rodney C; Utsunomiya, Satoshi

2017-07-14

Highly radioactive cesium-rich microparticles (CsMPs) released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) provide nano-scale chemical fingerprints of the 2011 tragedy. U, Cs, Ba, Rb, K, and Ca isotopic ratios were determined on three CsMPs (3.79-780 Bq) collected within ~10 km from the FDNPP to determine the CsMPs' origin and mechanism of formation. Apart from crystalline Fe-pollucite, CsFeSi 2 O 6  · nH 2 O, CsMPs are comprised mainly of Zn-Fe-oxide nanoparticles in a SiO 2 glass matrix (up to ~30 wt% of Cs and ~1 wt% of U mainly associated with Zn-Fe-oxide). The 235 U/ 238 U values in two CsMPs: 0.030 (±0.005) and 0.029 (±0.003), are consistent with that of enriched nuclear fuel. The values are higher than the average burnup estimated by the ORIGEN code and lower than non-irradiated fuel, suggesting non-uniform volatilization of U from melted fuels with different levels of burnup, followed by sorption onto Zn-Fe-oxides. The nano-scale texture and isotopic analyses provide a partial record of the chemical reactions that occurred in the fuel during meltdown. Also, the CsMPs were an important medium of transport for the released radionuclides in a respirable form.

Decision no. 2011-DC-0224 of the French nuclear safety authority from May 5, 2011, ordering the French atomic energy and alternative energies commission (CEA) to proceed to a complementary safety evaluation of some of its basic nuclear facilities in the eyes of the Fukushima Daiichi nuclear power plant accident

International Nuclear Information System (INIS)

2011-01-01

As a consequence of the accident of the Fukushima Daiichi nuclear power plant (Japan), the French Prime Minister entrusted the French nuclear safety authority (ASN) with the mission to carry out a safety analysis re-evaluation of the French nuclear facilities, and in particular the nuclear power plants. A decision has been addressed by the ASN to each nuclear operator with the specifications of this safety re-evaluation analysis and the list of facilities in concern. This document is the decision addressed to the French atomic energy commission (CEA). (J.S.)

Interpreting the deposition and vertical migration characteristics of 137Cs in forest soil after the Fukushima Dai-ichi Nuclear Power Plant accident.

Science.gov (United States)

Kang, Seongjoo; Yoneda, Minoru; Shimada, Yoko; Satta, Naoya; Fujita, Yasutaka; Shin, In Hwan

2017-08-01

We investigated the deposition and depth distributions of radiocesium in the Takizawa Research Forest, Iwate Prefecture, in order to understand the behavior of radionuclides released from the Fukushima Dai-ichi Nuclear Power Plant. The deposition distribution and vertical depth distribution of radiocesium in the soil were compared between topographically distinct parts of the forest where two different tree species grow. The results for all investigated locations show that almost 85% of the radiocesium has accumulated in the region of soil from the topmost organic layer to a soil depth of 0-4 cm. However, no activity was detected at depths greater than 20 cm. Analysis of the radiocesium deposition patterns in forest locations dominated by either coniferous or deciduous tree species suggests that radiocesium was sequestered and retained in higher concentrations in coniferous areas. The deposition data showed large spatial variability, reflecting the differences in tree species and topography. The variations in the measured 137 Cs concentrations reflected the variability in the characteristics of the forest floor environment and the heterogeneity of the initial ground-deposition of the Fukushima fallout. Sequential extraction experiments showed that most of the 137 Cs was present in an un-exchangeable form with weak mobility. Nevertheless, the post-vertical distribution of 137 Cs is expected to be governed by the percentage of exchangeable 137 Cs in the organic layer and the organic-rich upper soil horizons.

Radiation occupational health interventions offered to radiation workers in response to the complex catastrophic disaster at the Fukushima Daiichi Nuclear Power Plant

International Nuclear Information System (INIS)

Shimura, Tsutomu; Yamaguchi, Ichiro; Terada, Hiroshi; Kunugita, Naoki; Okuda, Kengo; Svendsen, E.R.

2015-01-01

The Fukushima Daiichi Nuclear Power Plant (NPP) 1 was severely damaged from the chain reaction of the Great East Japan Earthquake and Tsunami on 11 March 2011, and the consequent meltdown and hydrogen gas explosions. This resulted in the worst nuclear accident since the Chernobyl accident of 1986. Just as in the case of Chernobyl, emergency workers were recruited to conduct a wide range of tasks, including disaster response, rescuing activities, NPP containment, and radiation decontamination. This paper describes the types and efficacy of the various occupational health interventions introduced to the Fukushima NPP radiation workers. Such interventions were implemented in order to prevent unnecessary radiation overexposure and associated adverse health effects and work injuries. Less than 1% of all emergency workers were exposed to external radiation of >100 mSv, and to date no death or health adversities from radiation have been reported for those workers. Several occupational health interventions were conducted, including setting of new regulatory exposure limits, improving workers' radiation dosimetry, administration of stable iodine, running an occupational health tracking system, and improving occupational medicine and preventative care. Those interventions were not only vital for preventing unnecessary radiation, but also for managing other general health issues such as mental health, heat illness and infectious disease. Long-term administration of the aforementioned occupational health interventions is essential to ensure the ongoing support and care for these workers, who were put under one of the most severe occupational health risk conditions ever encountered. (author)

Some lessons on radiological protection learnt from the accident at the Fukushima Dai-ichi nuclear power plant

International Nuclear Information System (INIS)

Kai, M

2012-01-01

The accident at the Fukushima Dai-ichi nuclear power plant released a large quantity of radioactive iodine and caesium into the environment. In terms of radiological protection, the evacuation and food restrictions that were adopted in a timely manner by the authorities effectively reduced the dose received by people living in the affected area. Since late March, the transition from an emergency to an existing exposure situation has been in progress. In selecting the reference exposure levels in some areas under an existing exposure situation, the authorities tried to follow the situation-based approach recommended by the ICRP. However, a mixture of emergency and post-emergency approaches confused the people living in the contaminated areas because the reactor conditions continued to be not completely stable. In deriving the criteria in an existing exposure situation, the regulatory authority selected 20 mSv y −1 . The mothers in the affected area believed that a dose of 20 mSv y −1 was unacceptably high for children since 1 mSv y −1 is the dose limit for the public under normal conditions. Internet information accelerated concern about the internal exposure to children and the related health effects. From some experiences after the accident the following lessons could be learned. The selection of reference doses in existing exposure situations after an accident must be openly communicated with the public using a risk-informed approach. The detriment-adjusted nominal risk coefficient was misused for calculating the hypothetical number of cancer deaths by some non-radiation experts. It would not be possible to resolve this problem unless the ICRP addressed an alternative risk assessment to convey the meaning and associated uncertainty of the risk to an exposed population. A situation-based approach in addition to a risk-informed approach needs to be disseminated properly in order to select the level of protection that would be the best possible under the

Measurement of the environmental radiation dose due to the accident at the Fukushima Daiichi Nuclear Power Plant

International Nuclear Information System (INIS)

Yamamoto, Tomoaki; Muroi, Kenzo; Maruyama, Sumito; Koike, Takahisa; Matsuda, Marina; Katsumata, Kenichiro

2013-01-01

On March 11, 2011, an undersea megathrust earthquake caused a tsunami that inflicted serious damage to the Fukushima Daiichi Nuclear Power Plant (FDNPP). On March 12, 2011, we began measuring environmental radiation doses and identifying fission product radionuclides at the International University of Health and Welfare (IUHW). The purpose of this investigation is to estimate the external exposure dose of fission products from FDNPP. Measurements were performed between March 12 and August 31, 2011. A NaI(Tl) scintillation survey meter was used to measure the environmental radiation dose, and air dust samplers and a NaI(Tl) scintillation spectrum analyzer were used to identify radionuclides in the atmosphere and soil. For estimating external doses, three lifestyle groups were considered viz. students or office workers, business persons, and farmers or construction workers. Increasing doses were detected on March 15 around noon, and the doses peaked on March 16. Post-peak, the doses decreased exponentially and became stable after two months. Immediately after the accident, some fission product radionuclides were detected in the atmosphere and in the soil samples. Almost no radionuclides were detected in the atmosphere approximately one month after the first analysis; although the radiation was decaying, radionuclides were detected in the soil and were isolated. The external dose varied with the supposed lifestyle; assuming that the abundance ratio of Cs-134 to Cs-137 was 1:1, the annual external doses for the considered lifestyles were 1.069 mSv for students or office workers, 1.672 mSv for business persons, and 2.044 mSv for farmers or construction workers. These doses are sufficiently small so that most residents including children, living near IUHW, would not be affected. Further investigation of the internal exposure is necessary for a better estimate of the effective doses. External exposure to fission product radionuclides is within safe levels, and while

Summarized achievement report on the Sunshine Project in fiscal 1980 (Hydrogen energy); 1980 nendo seika hokokusho gaiyoshu. Suiso energy

Energy Technology Data Exchange (ETDEWEB)

NONE

1981-04-01

This paper summarizes the achievement report on the Sunshine Project in fiscal 1980 for hydrogen energy research. In hydrogen manufacturing using the electrolytic process, improvements were made on membranes and electrodes. Solid electrolyte electrolysis is also under research. Researches are continued on reaction, separating operation, and device materials for the iodine system cycle in the thermo-chemical method. In the iron system cycle, a reaction experimenting equipment was fabricated on the trial basis, and tests and evaluation were performed on the material and heat balances. In the mixed system cycle, researches on the light irradiation electrolytic process were continued, whereas the light collecting rate was raised by using a lens to increase light intensity, having enhanced successfully the reaction rate to 60 to 80%. A heat diffusion column for HI decomposition and separation (hydrogen acquisition) was discussed in terms of chemical engineering. Development works are continued on metal hydrides for hydrogen transportation, and durability tests are also being performed. Same applies to hydrogen storage. A model burner was fabricated on the trial basis, and catalytic combustion was studied as development of a combustion technology that matches the requirements for safe hydrogen combustion and suppression of NOx emission. Searches were continued on catalysts and solid electrolyte materials for fuel cells. Thin film sold electrolyte fuel cells constructed by using the evaporation process are also being studied. The paper also describes measures for hydrogen safety assurance and researches on energy systems. (NEDO)

Fiscal 1997 achievement report. Research and development of synergy ceramics; 1997 nendo synergy ceramics no kenkyu kaihatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-03-01

Research and development is conducted on two subjects, that is, 1) hyper organized structure control technology and 2) structural element control technology. In addition, joint research and development is conducted on the creation of new materials by hyper organized structure controlling, hyper organized structure controlling for ceramics by a structurization reaction process, designing of precursors to ceramics, and the hyper organized structure control for ceramics by nanostructure process control. The joint research and development endeavors further deal with re-entrusted projects which involve researches on sintered structure control by powdery particulate structure control; dynamic process of synergy ceramics; oxynitride liquids, glasses, and glass-ceramics; and multifunctional ceramic laminates for engineering applications. Under subject 1), researches are made on the development of precursors into ceramics by utilizing chemical reactions of organic metal compounds, and analyses are conducted into the effects, exerted by the molecular structures of precursors and the conditions of a reaction for their development into ceramics, on the microstructures and various properties of the ceramics to be composed. Under subject 2), high strength, great hardness, and high resistance to wear are realized by allowing the precipitation of nano-particulates in crystals of a fine and very compact sintered body of alumina. (NEDO)

Achievement report on developing inverse manufacturing system in fiscal 1998; 1998 nendo inverse manufacturing system no kaihatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-03-01

Research and development has been performed on a circulating type production system, or an inverse manufacturing system, to minimize the environmental load in the entire life cycle of industrial products from design to manufacturing, maintenance, recovery, and re-utilization. In developing the recycling information system, discussion and extraction were executed on the data to be exchanged between manufacturers and users in the inverse society. A new individual parts history control system was developed. In developing the recycling processing system, a prototype system was evaluated by using hypothetical data, wherein the possibility of improving the recycling processing efficiency and reducing the cost was verified. In addition, trial design was made on a recycling processing plant in consideration of the cost effect to get the future plant image. In fabricating the inverse manufacturing products, a prototype concept model was made for information terminal devices. Development was performed on such elementary technologies as the easy-to-disintegrate structure technology, self-integration connecting structure and environmental hysteresis detection system. (NEDO)

Fiscal 2000 achievement report. Welfare technosystem research and development (Mizusawa); 2000 nendo walfare technosystem kenkyu kaihatsu (Mizusawa) seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

For assisting aged people, healthy and living alone, in living without help, activities were conducted for (1) an electrical transmission experiment connecting residences (two, inhabited for the experiment) and a remote location (Techno-House) and (2) the development of a home server equipped with an electrocardiograph. Under item (1), data collected by sensors (occupancy sensor, open/close sensor, flame sensor, waterflow sensor) installed at the residences occupied by aged persons living alone were forwarded to Techno-House via CATV (cable television) and analyzed for the study of elderly people's behavior and daily life pattern. It was found that using this system the behavior of elderly people living alone might be detected even in the absence of their intention to report or communicate. Under item (2), an Ni-based electrode sheet was fabricated and installed in a bed and, via the sheet and a CATV channel, cardiographic waveforms were transmitted to Techno-House where the data were put into an analyzer for the examination of the elderly person's physical conditions. (NEDO)

Fiscal 2000 achievement report. Welfare technosystem research and development (Sapporo); 2000 nendo Welfare technosystem kenkyu kaihatsu (Sapporo) seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

Activities are conducted on system technologies for ensuring comfortable living circumstances and thereby helping aged or handicapped people live independently in snowy cold regions. The research and development efforts center about the three fields of (1) in-house systems to help aged or handicapped people live an independent life, (2) in-home care equipment systems suitable for advanced welfare oriented residences, and (3) user interface controllers to improve on operating sensation in a motor driven wheelchair. In field (1), studies involve the development of low floor residences for snowy cold regions, improvement on entrances for independent residences helping the inhabitants lead an independent life, and functionally excellent designs for handrails for steps, stairs, or bathrooms. In field (2), surveys are conducted concerning design improvements and their acceptability relative to a universal welfare equipment controller, optimum sound that welfare equipment alarms should produce, and transfer devices. In field (3), studies are made about motor driven wheelchair controllers. (NEDO)

Fiscal 2000 achievement report. Welfare technosystem research and development (Niihama); 2000 nendo walfare technosystem kenkyu kaihatsu (Niihama) seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

Efforts are made to develop welfare equipment systems for helping people needing care lead an independent life. In collecting data on the transfer of patients and carrying out research and development in this connection, activities are conducted to develop (1) a transfer wheelchair and a transfer aiding wheelchair, (2) a simplified transfer type toilet, and (3) a tilt mechanism installable on a standard wheelchair. Under item (1), a wheelchair and an auxiliary wheelchair enabling the transfer of a person who cannot move without help between a wheelchair and an automobile are experimentally built. Under item (2), a simplified transfer type toilet to which a single attendant can easily guide the patient from the bed is developed. Under item (3), a tilt mechanism is developed, installable on a wheelchair to recline the same for the aged person to assume a comfortable attitude. In the development of a portable character reading device, a finger tip reader was experimentally manufactured for reading Japanese characters. (NEDO)

Fiscal 2000 achievement report. Welfare technosystem research and development (Ube); 2000 nendo walfare technosystem kenkyu kaihatsu (Ube) seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

Efforts continue to develop welfare nursing equipment for helping persons in need of nursing care or handicapped persons who live an independent life. Efforts are exerted in three fields for developing (1) a motor driven wheelchair in which the occupant feels as if driving a car, (2) an online cardiac function monitoring system using a cardiac sound sensor, (3) an automatic pressure belt for patients of postural low blood pressure, (4) and a seated position aiding and stabilizing device for workers with legs not fully useful. In field (1), the steering wheel, brake, and driving system are contrived so that the occupant may easily drive the wheelchair as if in an automobile driver's seat. In field (2), a device is developed to monitor and examine the heart rate and respiration rate, for which a cardiac sensor has to be installed on the water bed or an air mattress. In field (3), a computer controlled automatic pressure belt is developed for patients of myelopathy or cerebrovascular disease. In field (4), a work assisting device is developed to help seated workers with leg troubles. (NEDO)

Fiscal 1999 achievement report. Research and development of synergy ceramics; 1999 nendo synergy ceramics no kenkyu kaihatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-03-01

Studies are conducted on three subjects, which are the development of 1) high-temperature energy materials technology, 2) ultrasophisticated materials technology, and 3) high-performance active materials technology. Under subject 1), high-strength porous materials are to be developed, which are resistant to heat and corrosion, tolerant of damage and deformation, and light in weight. In addition, relative to fluid transmission, materials are to be developed, which are highly resistant to heat, corrosion, and thermal impact, and capable of separating and removing particulates of powder dust. Under subject 2), efforts are under way to develop two technologies, related to materials creation and their application. The former technology involves the development of a process of simultaneously equipping materials with high wear resistance, desired friction factors, and desired mechanical and thermal characteristics; a process of equipping them with a trace damage detecting function; and a process of simultaneously equipping them with functions of restoration from accidents and of self-lubrication. Relative to the latter technology, efforts are conducted, in coordination with the endeavors for the above-said materials creation technology, to develop materials and their application with attention paid to some specified functions. Under subject 3), self-complete type ceramic materials not requiring an external driving power source are to be developed, in which a selective cleaning function and environmental energy conversion function are amalgamated. (NEDO)

Fiscal 2000 achievement report. Welfare technosystem research and development (Chofu); 2000 nendo welfare technosystem kenkyu kaihatsu (Chofu) seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

Research and development efforts are exerted to realize (1) a variable function residential circumstance system for the aged people and (2) a medical welfare and life assisting information system for helping the aged or handicapped people lead an independent life. Under item (1), a variable function residential circumstance system under which functions of the residence may be changed dependent upon inhabitants' degree of debility will be developed, and an information system will be developed under which medical welfare assistance and life assistance are integrated. Under item (2), residences, welfare appliances, and nurse/attendant assisting systems will be assessed and examined. In fiscal 2000, under item (1), a variable function residential unit was fabricated and was inhabited experimentally by people approximately 1 to 4 in the degree of need for nursing care, and problems were isolated to be discussed toward putting the system to practical use. Under item (2), physical power required for nursing and attending was measured using medical assistance appliances for in-home nursing care installed at Welfare Technohouse Chofu, and ergonomic studies were conducted with a view to relieving the load to be imposed upon those engaged in the nursing and attending work. (NEDO)

FY 1981 Report on the results of Sunshine Project. Coal energy; 1981 nendo sunshine keikaku seika hokokusho. Sekitan energy

Energy Technology Data Exchange (ETDEWEB)

NONE

1981-07-01

This report presents the results of (researches on solvolysis liquefaction mechanisms and reaction promotion with oil- and coal-based solvents), conducted as part of the research and development project for coal liquefaction techniques. The FY 1981 program includes researches on (1) the effects of liquefaction reaction conditions on liquefaction yield and production of light products for coal species of low degree of carbonization, including brown coal, (2) the effects of pretreatment of coal on its liquefaction reactivity, and (3) up-grading of the solvolysis coal liquid (SCL). For the item (1), HA240 (hydrogenated Ashland's A240) is used to investigate its liquefaction capacity for various coal species of low degree of carbonization, including brown coal. For the item (2), the effects of pretreatment in a hot water bath with reflux was investigated for sub-bituminous coal in the FY 1980. In the FY 1981, various pretreatment methods are attempted for enhancing liquefaction reactivity of brown coal. As a result, it is found that ash content of brown coal is decreased to one-third of the initial level, when it is treated in a diluted hydrochloric acid bath with reflux. For the item (3), SCL hydrogenated by Birch reduction (B-SCL, 1) is compared with H-SCL with respect to properties, structures and thermal crackability, to discuss the items required for the catalyst to be used in the second stage by clarifying effectiveness of the catalyst. (NEDO)

Summary of the FY 1988 Sunshine Project results. Hydrogen energy; 1988 nendo sunshine keikaku seika hokokusho gaiyoshu. Suiso energy

Energy Technology Data Exchange (ETDEWEB)

NONE

1989-04-01

Outlined herein are the results of researches on hydrogen energy as part of the FY 1988 Sunshine Project results. Researches on the techniques for producing hydrogen by electrolysis of water using a polymer electrolyte include development of power-supplying materials for electrolysis at high current density, and basic studies on the electrolysis using an OH ion conducting type polymer electrolyte. Researches on the techniques for producing hydrogen by electrolysis with hot steam include development of the materials, techniques for processing these materials, and electrolysis performance tests. Researches on the techniques for transporting hydrogen by metal hydrides include development of hydrogen-occluding alloys of high bulk density, and techniques for evaluating characteristics of metal hydrides. Researches on the techniques for storing hydrogen include those on alloy molding/processing techniques, hydrogen-storing metallic materials, and new hydrogen-storing materials. Researches on the techniques for utilizing hydrogen include those on energy conversion techniques using hydrogen-occluding alloys, and hydrogen-fueled motors. Researches on the techniques for safety-related measures include those on prevention of embrittlement of the system materials by hydrogen. (NEDO)

Summary of the FY 1989 Sunshine Project results. Hydrogen energy; 1989 nendo sunshine keikaku seika hokokusho gaiyoshu. Suiso energy

Energy Technology Data Exchange (ETDEWEB)

NONE

1990-04-01

Outlined herein are the results of researches on hydrogen energy as part of the FY 1989 Sunshine Project results. Researches on the techniques for producing hydrogen by electrolysis of water using a polymer electrolyte include those on the SPE electrolysis at high temperature and current density, and basic studies on the electrolysis using an OH ion conducting type polymer electrolyte. Researches on the techniques for producing hydrogen by electrolysis with hot steam include development of the materials, techniques for processing these materials, and electrolysis performance tests. Researches on the techniques for transporting hydrogen by metal hydrides include development of hydrogen-occluding alloys of high bulk density, and techniques for evaluating characteristics of metal hydrides. Researches on the techniques for storing hydrogen include those on hydrogen-storing metallic materials, alloy molding/processing techniques, and new hydrogen-storing materials. Researches on the techniques for utilizing hydrogen include those on energy conversion techniques using hydrogen-occluding alloys, and hydrogen-fueled motors. Researches on the techniques for safety-related measures include those on prevention of embrittlement of the system materials by hydrogen. (NEDO)

Fiscal 2000 achievement report. Welfare technosystem research and development (Kamogawa); 2000 nendo welfare technosystem kenkyu kaihatsu (Kamogawa) seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

For the purpose of assisting in-home medical care, a system to enable in-home acquisition, compression, accumulation, distribution, and regeneration of auscultatory sounds (cardiac sound, respiratory sound) is added to telemedicine assisting system technologies for remotely located doctors' decisions and instructions for in-home medical care. In fiscal 2000, for improvement on the already-developed system, operationality was improved, uptake was realized of still images (digital camera pictures) mainly for diseases in dematology where such is strongly demanded, and a transmitter function was augmented. The system enables the PHS (personal handyphone system) aided exchange of medical data between portable terminals on patrol and (doctors') personal computers through the personal computer server in the hospital. Doctors are able to administer remote telemedicine now that biomimetic information on remotely located patients such as still medical images and auscultatory sounds necessary for diagnosing is available in the hospital. (NEDO)

Fallout and drinking water contamination by I-131 and Cs-134, 137 in Japan, from the Fukushima Daiichi NPS accident

Energy Technology Data Exchange (ETDEWEB)

Kelecom, Alphonse; Miyashita, Erika; Kelecom, Patrick Vicent [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil)

2011-07-01

The earthquake followed by a tsunami in Japan, on last March 11, seriously damaged four of the six reactors of the Fukushima Daiichi nuclear power station (NPS). Radioactive smokes and highly contaminated water were released for weeks to the environment. Since March 12, when the plant operator TEPCO and Japan's nuclear agency (NISA) confirmed the presence of radionuclides near the NPS, a giant environmental monitoring operation was set up, covering the entire Japanese territory. Daily thousands measurements are realized. We here analyze data released during 60 days on I-131 and Cs-134,137 radioactive concentrations in drinking water and fallout for 45 prefectures. Miyagi and Fukushima, that requires a separate study, are not considered here. Drinking water contamination by I-131 was observed in 13 prefectures, including Tokyo. The most impacted one was Tochigi (maximum of 110 Bq/l, March 24). This value turned water not drinkable for infants and babies. Cs-137 was detected in drinking water in 8 prefectures, with a maximum level of 18 Bq/l in Ibaraki. These levels do not affect potability of tap water. I-131 was observed in fallout in 27 prefectures, with level reaching 93 kBq/m2 in Ibaraki and 36 kBq/m{sup 2} in Tokyo on March 21 and 23 respectively. Fallout of Cs-137 was observed in 19 prefectures. The maximum deposition occurred again in Ibaraki (13kBq/m{sup 2}, March 21) and in Tokyo (5.3 kBq/m2, March 22). Since mid April, only trace contamination has been observed for both radionuclides in drinking water. Sporadically medium levels of Cs-137 are still observed in fallout. (author)

Fallout and drinking water contamination by I-131 and Cs-134, 137 in Japan, from the Fukushima Daiichi NPS accident

International Nuclear Information System (INIS)

Kelecom, Alphonse; Miyashita, Erika; Kelecom, Patrick Vicent

2011-01-01

The earthquake followed by a tsunami in Japan, on last March 11, seriously damaged four of the six reactors of the Fukushima Daiichi nuclear power station (NPS). Radioactive smokes and highly contaminated water were released for weeks to the environment. Since March 12, when the plant operator TEPCO and Japan's nuclear agency (NISA) confirmed the presence of radionuclides near the NPS, a giant environmental monitoring operation was set up, covering the entire Japanese territory. Daily thousands measurements are realized. We here analyze data released during 60 days on I-131 and Cs-134,137 radioactive concentrations in drinking water and fallout for 45 prefectures. Miyagi and Fukushima, that requires a separate study, are not considered here. Drinking water contamination by I-131 was observed in 13 prefectures, including Tokyo. The most impacted one was Tochigi (maximum of 110 Bq/l, March 24). This value turned water not drinkable for infants and babies. Cs-137 was detected in drinking water in 8 prefectures, with a maximum level of 18 Bq/l in Ibaraki. These levels do not affect potability of tap water. I-131 was observed in fallout in 27 prefectures, with level reaching 93 kBq/m2 in Ibaraki and 36 kBq/m 2 in Tokyo on March 21 and 23 respectively. Fallout of Cs-137 was observed in 19 prefectures. The maximum deposition occurred again in Ibaraki (13kBq/m 2 , March 21) and in Tokyo (5.3 kBq/m2, March 22). Since mid April, only trace contamination has been observed for both radionuclides in drinking water. Sporadically medium levels of Cs-137 are still observed in fallout. (author)

The accident at TEPCO's Fukushima-Daiichi Nuclear Power Station: What went wrong and what lessons are universal?

Energy Technology Data Exchange (ETDEWEB)

Omoto, Akira, E-mail: akira.omoto@mac.com

2013-12-11

After a short summary of the nuclear accident at the Fukushima Daiichi Nuclear Power Station, this paper discusses “what went wrong” by illustrating the problems of the specific layers of defense-in-depth (basic strategy for assuring nuclear safety) and “what lessons are universal.” Breaches in the multiple layers of defense were particularly significant in respective protection (a) against natural disasters (first layer of defense) as well as (b) against severe conditions, specifically in this case, a complete loss of AC/DC power and isolation from the primary heat sink (fourth layer of defense). Confusion in crisis management by the government and insufficient implementation of offsite emergency plans revealed problems in the fifth layer of defense. By taking into consideration managerial and safety culture that might have relevance to this accident, in the author's view, universal lessons are as follows: a)Resilience: the need to enhance organizational capabilities to respond, monitor, anticipate, and learn in changing conditions, especially to prepare for the unexpected. This includes increasing distance to cliff edge by knowing where it exists and how to increase safety margin. b)Responsibility: the operator is primarily responsible for safety, and the government is responsible for protecting public health and environment. For both, their right decisions are supported by competence, knowledge, and an understanding of the technology, as well as humble attitudes toward the limitations of what we know and what we can learn from others. c)Social license to operate: the need to avoid, as much as possible regardless of its probability of occurrence, the reasonably anticipated environmental impact (such as land contamination), as well as to build public confidence/trust and a renewed liability scheme.

Observation of fallout deposition in an outdoor swimming pool 50 km away from the Fukushima Daiichi nuclear power plant

International Nuclear Information System (INIS)

Saegusa, Jun; Yasuda, Ryo; Kurikami, Hiroshi

2014-01-01

After the accident at the Fukushima Daiichi nuclear power plant (NPP), outdoor school swimming pools at Fukushima were decontaminated to curb the redistribution of radioactivity into downstream farmlands. In the process, the radioactivity concentrations of the pool water and sediment substances (residue) were measured to estimate the deposition density of the fallout. At a pool situated 50 km away from the NPP, the average concentrations of radiocesium ( 134+137 Cs) for the water and residue were quantified as 170 Bq L −1 and 3.6 × 10 5 Bq kg −1 , respectively. Taking account of the radioactivity concentrations and of the water balance in and around the pool, the deposition density of radiocesium, as of August 2011, was precisely determined to be 0.32 ± 0.03 MBq m −2 (k = 1). The density corroborated the previous results obtained by other methods, i.e., airborne surveys, in-situ Ge surveys and soil samplings at neighboring locations. Other than radiocesium, the only gamma-emitting nuclide detected was 110m Ag, with a concentration of 560 Bq kg −1 in the residue. The radioactivity concentrations of 89 Sr, 90 Sr, 238 Pu and 239+240 Pu in the water were all less than the minimum detectable activities – 2, 0.1, 0.002 and 0.002 Bq L −1 , respectively. - Highlights: • Deposition density of radiocesium was estimated at a swimming pool in Fukushima. • The density was determined with a small standard uncertainty of approximately 10%. • Water balance was simulated for estimating radioactivity budget in the pool. • Detected gamma-emitting nuclide was 110m Ag other than radiocesium. • Radiocesium was much dominant compared with 89 Sr, 90 Sr, 110m Ag, 238 Pu and 239+240 Pu

Modelling the transport of radioactive cesium released from the Fukushima Dai-ichi NPP with sediments through the hydrologic system

Science.gov (United States)

Kinouchi, T.; Omata, T.; Wei, L.; Liu, T.; Araya, M.

2013-12-01

Due to the accident of the Fukushima Dai-ichi Nuclear Power Plant on March 2011, a huge amount of radionuclides including Cesium-134 and Cesium-137 was deposited over the main island of Japan and the Pacific Ocean, resulting in further transfer and diffusion of Cesium through the atmospheric flow, watershed hydrological processes, and terrestrial ecosystem. Particularly, for the transfer of Cesium-134 and Cesium-137, sediments eroded and transported by the rainfall-runoff processes play an important role as Cesium tends to be strongly adsorbed to soil particles such as clay and silt. In this study, we focus on the transport of sediment and adsorbed Cesium in the watershed-scale hydrologic system to predict the long-term change of distribution of Cesium and its discharge to rivers and ocean. We coupled a physically-based distributed hydrological model with the modules of erosion and transport of sediments and adsorbed Cesium, and applied the coupled model to the Abukuma River watershed, which is located over the area of higher deposition of Cesium. In the model, complex land use and land cover distributions, and the effect of human activities such as irrigation, dam control and urban drainage system are taken into accounts. Simulation was conducted for the period of March 2011 until August 2012, with initial spatial distribution of Cesium-134 and Cesium-137 obtained by the airborne survey. Simulated flow rates and sediment concentrations agreed well with observed, and found that since the accident, two major storms in July and September 2011 transported about 50% of total sediments transported during the simulated periods. Cesium concentration in the sediment was reproduced well except for the difference in the initial periods. This difference is attributable to the uncertainty arisen from the initial distribution of Cesium in the soil and the transfer of Cesium from the forest canopy.

Radiocesium contamination measurement and prospect for future use of Pinus thunbergii pinecones and leaves collected in Fukushima City as children's play and craft materials after the accident at TEPCO's Fukushima Daiichi Nuclear Power Plant

International Nuclear Information System (INIS)

Sugiura, Hiroyuki; Kawano, Keisuke; Kayama, Yukihiko

2013-01-01

Pollutant on the leaves and pinecones of Pinus thunbergii contaminated by radiocesium in Fukushima City were measured, the safe use of the leaves and pinecones as children's toys and craft materials was prospected after the accident at the TEPCO's Fukushima Daiichi nuclear power plant. The radiocesium concentration on Pinus thunbergii leaves on February 22, 2013 was 1/5.7 of the concentration on May 2, 2012. The radiocesium concentration on pinecones was high (16,300 Bq/kg). Radiocesium attached to the latex glove worn when collecting polluted pinecones, and this level fell by 1/5.2 when the polluted glove was washed. Negligible amount of radiocesium was detected in the used glove for collecting of dirty pinecones after painting. It is reasonable to assume that the use of pinecones as craft materials will be possible in the near future because the radiocesium concentration levels are expected to decrease after 2014. (author)

The construction for remediation work of contaminated water at Fukushima Daiichi Nuclear Power Plant. Closure work of seawater piping trench and screen pump chamber

International Nuclear Information System (INIS)

Hibi, Yasuki; Yanai, Shuji; Nishikori, Kazumasa; Soma, Yu

2016-01-01

In the seawater piping trench of Fukushima Daiichi Nuclear Power Plant, highly contaminated water was stagnating, which flowed in from the reactor building and turbine building affected by the tsunami caused by the Tohoku Pacific Ocean Earthquake. Although the screen pump chamber, adjacent to the seawater piping trench, escaped from the inflow and retention of contaminated water, it was exposed to the leakage risk of contaminated water from the seawater piping trench. As measures against these conditions, the following emergency work was applied: (1) contaminated water replacement and removal operation based on the implantation of fillers into the seawater piping trench, and (2) closure operation of the screen pump chamber by implanting fillers into the screen pump chamber. In face of these operations, long-distance underwater flow special filler, high workable concrete, and underwater non-separation concrete were developed and used. The implantation of the long-distance underwater-flow special fillers into the seawater piping trench was successfully completed by filling to the tunnel top without gap and without water head difference, and by preventing the occurrence of movement or water path formation of the fillers in the initial curing process. Other fillers were also able to be implanted as planned. The leakage risk of contaminated water to the periphery could be suppressed to a large extent by this work. (A.O.)

Measurement of air dose rates over a wide area around the Fukushima Dai-ichi Nuclear Power Plant through a series of car-borne surveys.

Science.gov (United States)

Andoh, Masaki; Nakahara, Yukio; Tsuda, Shuichi; Yoshida, Tadayoshi; Matsuda, Norihiro; Takahashi, Fumiaki; Mikami, Satoshi; Kinouchi, Nobuyuki; Sato, Tetsuro; Tanigaki, Minoru; Takamiya, Koichi; Sato, Nobuhiro; Okumura, Ryo; Uchihori, Yukio; Saito, Kimiaki

2015-01-01

A series of car-borne surveys using the Kyoto University RAdiation MApping (KURAMA) and KURAMA-II survey systems has been conducted over a wide area in eastern Japan since June 2011 to evaluate the distribution of air dose rates around the Fukushima Dai-ichi Nuclear Power Plant and to evaluate the time-dependent trend of decrease in air dose rates. An automated data processing system for the KURAMA-II system was established, which enabled rapid analysis of large amounts of data obtained using about 100 KURAMA-II units. The initial data used for evaluating the migration status of radioactive cesium were obtained in the first survey, followed by other car-borne surveys conducted over more extensive and wider measurement ranges. By comparing the measured air dose rates obtained in each survey (until December 2012), the decreasing trend of air dose rates measured through car-borne surveys was found to be more pronounced than those expected on the basis of the physical decay of radioactive cesium and of the air dose rates measured using NaI (Tl) survey meters in the areas surrounding the roadways. In addition, it was found that the extent of decrease in air dose rates depended on land use, wherein it decreased faster for land used as building sites than for forested areas. Copyright © 2014 Elsevier Ltd. All rights reserved.

Decision no. 2011-DC-0216 of the French nuclear safety authority from May 5, 2011, ordering the Laue Langevin Institute to proceed to a complementary safety evaluation of its basic nuclear facility (high flux reactor - INB no. 67) in the eyes of the Fukushima Daiichi nuclear power plant accident

International Nuclear Information System (INIS)

2011-01-01

As a consequence of the accident of the Fukushima Daiichi nuclear power plant (Japan), the French Prime Minister entrusted the French nuclear safety authority (ASN) with the mission to carry out a safety analysis re-evaluation of the French nuclear facilities, and in particular the nuclear power plants. A decision has been addressed by the ASN to each nuclear operator with the specifications of this safety re-evaluation analysis and the list of facilities in concern. This document is the decision addressed to the Laue Langevin Institute, operator of the high flux research reactor (RHF) of Grenoble (France). (J.S.)

An extensive study of the concentrations of particulate/dissolved radiocaesium derived from the Fukushima Dai-ichi Nuclear Power Plant accident in various river systems and their relationship with catchment inventory

International Nuclear Information System (INIS)

Yoshimura, Kazuya; Onda, Yuichi; Sakaguchi, Aya; Yamamoto, Masayoshi; Matsuura, Yuki

2015-01-01

An extensive investigation of particulate radiocaesium in suspended solids and dissolved radiocaesium in river water was undertaken at 30 sites in Fukushima and Miyagi Prefectures in December 2012, and their relationships with catchment inventory and the solid/liquid distribution coefficient (K d ) were evaluated. Rivers located in the coastal region on the north side of the Fukushima Dai-ichi Nuclear Power Plant exhibited relatively higher particulate radiocaesium concentrations. Significant correlations were found between concentrations of particulate/dissolved radiocaesium and average catchment inventories, indicating that the concentrations of particulate/dissolved radiocaesium could be approximated from the catchment inventory. Particulate radiocaesium concentration was significantly correlated with dissolved radiocaesium concentration (with the exception of concentrations measured in estuaries), and the geometric mean K d was calculated as 3.6 × 10 5 with a 95% confidence interval of 2.6–5.1 × 10 5 . - Highlights: • Particulate radiocaesium concentration correlated with catchment inventory. • Particulate size can be an important factor of the correlation. • Solid/liquid distribution coefficients were obtained for extensive area

Simulation analysis on accident at Fukushima Daiichi Nuclear Power Plant Unit 2 by SAMPSON code

International Nuclear Information System (INIS)

Takahashi, Atsuo; Pellegrini, Marco; Mizouchi, Hideo; Suzuki, Hiroaki; Naitoh, Masanori

2015-01-01

The accident occurred at the Fukushima Daiichi Nuclear Power Plant Unit 2 has been investigated by the severe accident analysis code, SAMPSON with more realistic boundary conditions and newly introduced models. In Unit 2, the Reactor Core Isolation Cooling system (RCIC) is thought to have worked for unexpectedly long time (about 70 hours) without batteries. It is thought to be due to balance between injected water from the RCIC pump and supplied mixture of steam and water to the RCIC turbine. To confirm the RCIC working condition and reproduce the measured plant properties, such as pressure and water level in the reactor pressure vessel (RPV), we introduced two-phase turbine driven pump model into SAMPSON. In the model, mass flow rate of water injected by RCIC was calculated through mass flow rate of steam included in extracted two-phase flow, steam generated from flashing of water included in extracted two-phase flow, and turbine efficiency degradation originated by the mixture of steam and water flowing to the RCIC turbine. To reproduce the dry well (DW) pressure, we assumed that torus room was flooded by the tsunami and heat was removed from the suppression chamber to the sea water. Simulation results by SAMPSON basically agree with the measured values such as pressure in the RPV and in the DW until several days after the scram. However, some contradictions between the simulation results and the measured values, such as that inversion of the RPV pressure at 10 hours after scram in the measurement happened at 14 hours in the simulation and that the DW pressure showed different behavior between simulation and measurement when SRV started periodic operation at 71 hours, are still remain and are under consideration. In the current calculation, model for falling core to the lower plenum was modified so that debris is not retained at the core plate based on observation of the XR2-1 experiment. Additionally, model of the RPV failure by melting of the penetrating pipe

Direct determination of tellurium in soil and plant samples by sector-field ICP-MS for the study of soil-plant transfer of radioactive tellurium subsequent to the Fukushima Daiichi Nuclear Power Plant accident

International Nuclear Information System (INIS)

Yang, Guosheng; Zheng, Jian; Tagami, Keiko; Uchida, Shigeo

2013-01-01

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident caused the release of large amounts of radioactive Te into the environment. Stable Te, as an analogue, is considered to be useful for the estimation of the soil-plant transfer of radioactive Te. It is necessary to estimate the radiation dose of Te that would result from food ingestion. However, due to the extremely low concentrations of Te in the environment, reported transfer factor values for Te are considerably limited. We report a sensitive analytical method for direct determination of trace Te in soil and plant samples using a sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS). The developed analytical method is characterized by a very low detection limit at the sub-parts per billion (ng g"-"1) level in soil and plant samples, and it has been applied to the study of soil-plant transfer to collect transfer factor data in Japan. (author)

Report of the results of the fiscal 1997 regional consortium R and D project. Regional consortium field / R and D on downsizing technology of machine tools (first fiscal year); 1997 nendo chiiki consortium kenkyu kaihatsu jigyo. Chiiki consortium energy bun`ya / kosaku kikai no downsizing gijutsu ni kansuru kenkyu kaihatsu (daiichi nendo) seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-03-01

The R and D were conducted aiming at downsizing machine tools by combining microfactory technology owned by Mechanical Engineering Laboratory, Agency of Industrial Science and Technology of MITI with fundamental element technology owned by industrial groups of machine tools. In fiscal 1997, as to the study of spindle drum indexing mechanism in making main spindle multiaxial, the following have been finished: the basic study through openness of controller and networks, confirmation of function of the equipment acquired, and initialization of the driver software. Relating to the study on machining conditions of dry machining processing, delivery and installation of cold air machining instrument have been finished. Concerning the optical measurement of spindle radial run-out vectors, a system to make optical no contact measurement of radial direction components of rotation error was constructed with high accuracy pin gauge attached to the work spindle clamp mechanism as a medium. About the study on sensor-based state recognition technology, specifications for various kinds of sensor were decided on. 5 refs., 67 figs., 3 tabs.

Report of the results of the fiscal 1997 regional consortium R and D project. Regional consortium energy field/R and D high performance flat panel display technology (first fiscal year); 1997 nendo chiiki consortium kenkyu kaihatsu jigyo. Chiiki consortium energy bun`ya / koseino flat panel display gijutsu no sogo kaihatsu kenkyu (daiichi nendo ) seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-03-01

One of the subjects in technology supporting the highly information-oriented society which will develop and diversify toward the 21st century is the construction of high grade man/machine interface. For it, high precision/high luminance/energy saving/thin plane displays are strongly requested. This R and D is to indicate models of systematical development in the region of element technology individually existing in the Shikoku area by forming a regional consortium in the industry/universities/government. Creation of new industries by gathering display related enterprises is a first step in a plan to realize `Display Island Shikoku.` As a concrete target, with the use of high-tech diamond semiconducting technology, a development is conducted of the high performance flat panel display using the negative electron affinity (NEA) electron emitter which drastically solves the problems such as luminance, visibility angle and response speed, the subjects on the commercialized liquid crystal flat panel display. 16 refs., 45 figs., 8 tabs.