Process criticality accident likelihoods, consequences and emergency planning

International Nuclear Information System (INIS)

McLaughlin, T.P.

1992-01-01

Evaluation of criticality accident risks in the processing of significant quantities of fissile materials is both complex and subjective, largely due to the lack of accident statistics. Thus, complying with national and international standards and regulations which require an evaluation of the net benefit of a criticality accident alarm system, is also subjective. A review of guidance found in the literature on potential accident magnitudes is presented for different material forms and arrangements. Reasoned arguments are also presented concerning accident prevention and accident likelihoods for these material forms and arrangements. (Author)

Prevention of the causes and consequences of a criticality accident - measures adopted in France

International Nuclear Information System (INIS)

Fruchard, Y.; Lavie, J.M.

1966-01-01

The question of safety in regard to criticality accident risks has two aspects: prevention of the cause and limitation of the consequences. These two aspects are closely connected. The effort devoted to prevention of the causes depends on the seriousness of the possible human psychologic and economic consequences of the accident. The criticality accidents which have occurred in the nuclear industry, though few in number, do reveal the imperfect nature of the techniques adopted to prevent the causes, and also constitute the only available realistic basis for evaluating the consequences and developing measures to limit them. The authors give a analysis of the known causes and consequences of past criticality accidents and on this basis make a number of comments concerning: the validity of traditional safety criteria, the probability of accidents for different types of operations, characteristic accidents which can serve as models, and the extent of possible radiological consequences. The measures adopted in France to limit the consequences of a possible criticality accident under the headings: location, design and lay-out of the installations, accident detection, and dosimetry for the exposed personnel, are briefly described after a short account of the criteria used in deciding on them. (author) [fr

ANS-8.23: Criticality accident emergency planning and response

International Nuclear Information System (INIS)

Pruvost, N.L.

1991-01-01

A study group has been formed under the auspices of ANS-8 to examine the need for a standard on nuclear criticality accident emergency planning and response. This standard would be ANS-8.23. ANSI/ANS-8.19-1984, Administrative Practices for Nuclear Criticality Safety, provides some guidance on the subject in Section 10 titled -- Planned Response to Nuclear Criticality Accidents. However, the study group has formed a consensus that Section 10 is inadequate in that technical guidance in addition to administrative guidance is needed. The group believes that a new standard which specifically addresses emergency planning and response to a perceived criticality accident is needed. Plans for underway to request the study group be designated a writing group to create a draft of such a new standard. The proposed standard will divide responsibility between management and technical staff. Generally, management will be charged with providing the necessary elements of emergency planning such as a criticality detection and alarm system, training, safe evacuation routes and assembly areas, a system for timely accountability of personnel, and an effective emergency response organization. The technical staff, on the other hand, will be made responsible for establishing specific items such as safe and clearly posted evacuation evacuation routes and dose criteria for personnel assembly areas. The key to the question of responsibilities is that management must provide the resources for the technical staff to establish the elements of an emergency response effort

JCO criticality accident termination operation

International Nuclear Information System (INIS)

Kanamori, Masashi

2010-07-01

In 2001, we summarized the circumstances surrounding termination of the JCO criticality accident based on testimony in the Mito District Court on December 17, 2001. JCO was the company for uranium fuels production in Japan. That document was assembled based on actual testimony in the belief that a description of the work involved in termination of the accident would be useful in some way for preventing nuclear disasters in the future. The description focuses on the witness' own behavior, and what he saw and heard, and thus is written from the perspective of action by one individual. This was done simply because it was easier for the witness to write down his memories as he remembers them. Description of the activities of other organizations and people is provided only as necessary, to ensure that consistency in the descriptive approach is not lost. The essentials of this report were rewritten as a third-person objective description in the summary of the report by the Atomic Energy Society of Japan (AESJ). Since then, comments have been received from sources such as former members of the Nuclear Safety Commission (Dr. Kenji Sumita and Dr. Akira Kanagawa), concerned parties from the former Science and Technology Agency, and reports from the JCO Criticality Accident Investigation Committee of the AESJ, and thus this report was rewritten to correct incorrect information, and add material where that was felt to be necessary. This year is the tenth year of the JCO criticality accident. To mark this occasion we have decided to translate the record of what occurred at the accident site into English so that more people can draw lessons from this accident. This report is an English version of JAEA-Technology 2009-073. (author)

First Responders and Criticality Accidents

Energy Technology Data Exchange (ETDEWEB)

Valerie L. Putman; Douglas M. Minnema

2005-11-01

Nuclear criticality accident descriptions typically include, but do not focus on, information useful to first responders. We studied these accidents, noting characteristics to help (1) first responders prepare for such an event and (2) emergency drill planners develop appropriate simulations for training. We also provide recommendations to help people prepare for such events in the future.

Development of the criticality accident analysis code, AGNES

International Nuclear Information System (INIS)

Nakajima, Ken

1989-01-01

In the design works for the facilities which handle nuclear fuel, the evaluation of criticality accidents cannot be avoided even if their possibility is as small as negligible. In particular in the system using solution fuel like uranyl nitrate, solution has the property easily becoming dangerous form, and all the past criticality accidents occurred in the case of solution, therefore, the evaluation of criticality accidents becomes the most important item of safety analysis. When a criticality accident occurred in a solution fuel system, due to the generation and movement of radiolysis gas voids, the oscillation of power output and pressure pulses are observed. In order to evaluate the effect of criticality accidents, these output oscillation and pressure pulses must be calculated accurately. For this purpose, the development of the dynamic characteristic code AGNES (Accidentally Generated Nuclear Excursion Simulation code) was carried out. The AGNES is the reactor dynamic characteristic code having two independent void models. Modified energy model and pressure model, and as the benchmark calculation of the AGNES code, the results of the experimental analysis on the CRAC experiment are reported. (K.I.)

A review of criticality accidents

International Nuclear Information System (INIS)

Stratton, W.R.; Smith, D.R.

1989-03-01

Criticality accidents and the characteristics of prompt power excursions are discussed. Forty-one accidental power transients are reviewed. In each case where available, enough detail is given to help visualize the physical situation, the cause or causes of the accident, the history and characteristics of the transient, the energy release, and the consequences, if any, to personnel and property. Excursions associated with large power reactors are not included in this study, except that some information on the major accident at the Chernobyl reactor in April 1986 is provided in the Appendix. 67 refs., 21 figs., 2 tabs

Recommendations about criticality accident dosimetry

International Nuclear Information System (INIS)

1975-07-01

The aims of criticality accident dosimetry and the characteristics peculiar to a critical burst being defined, the requirements to be fulfilled by a dosimetric system applied to this type of measurements are presented. The devices chosen by the C.E.A. Radiation Survey Divisions, simple and cheap, are described along with the main processes to be carried out in order to evaluate doses after an accident. The apparatus necessary for detector counting and the directions for use are presented in detail, allowing standardization of measurements. A set of linear formula enables to obtain, from these measurements, all required informations about neutron fluences and spectra, along with the suitable components of the dose at the irradiated people locations [fr

Workplace Accidents and Self-Organized Criticality

OpenAIRE

Mauro, John C.; Diehl, Brett; Marcellin, Richard F.; Vaughn, Daniel J.

2018-01-01

The occurrence of workplace accidents is described within the context of self-organized criticality, a theory from statistical physics that governs a wide range of phenomena across physics, biology, geosciences, economics, and the social sciences. Workplace accident data from the U.S. Bureau of Labor Statistics reveal a power-law relationship between the number of accidents and their severity as measured by the number of days lost from work. This power-law scaling is indicative of workplace a...

Lessons learned from early criticality accidents

International Nuclear Information System (INIS)

Malenfant, R.E.

1996-01-01

Four accidents involving the approach to criticality occurred during the period July, 1945, through May, 1996. These have been described in the format of the OPERATING EXPERIENCE WEEKLY SUMMARY which is distributed by the Office of Nuclear and Facility Safety. Although the lessons learned have been incorporated in standards, codes, and formal procedures during the last fifty years, this is their first presentation in this format. It is particularly appropriate that they be presented in the forum of the Nuclear Criticality Technology Safety Project Workshop closest to the fiftieth anniversary of the last of the four accidents, and that which was most instrumental in demonstrating the need to incorporate lessons learned

Criticality accident studies and methodology implemented at the CEA

International Nuclear Information System (INIS)

Barbry, Francis; Fouillaud, Patrick; Reverdy, Ludovic; Mijuin, Dominique

2003-01-01

Based on the studies and results of experimental programs performed since 1967 in the CRAC, then SILENE facilities, the CEA has devised a methodology for criticality accident studies. This methodology integrates all the main focuses of its approach, from criticality accident phenomenology to emergency planning and response, and thus includes aspects such as criticality alarm detector triggering, airborne releases, and irradiation risk assessment. (author)

Four years after the JCO criticality accident

International Nuclear Information System (INIS)

Sumita, Kenji

2003-01-01

It has been about four years since the first criticality accident in Japan. The JCO accident site was not so far from this auditorium. I have been asked to give a short review of important results from the various technical investigations on the accident that have been performed during the past four years. I will also give a short introduction to the changes that have been made in the nuclear safety regulation systems of the Japanese Government. (author)

Energy and angular responses of the criticality accident detector using a plastic scintillator

International Nuclear Information System (INIS)

Tsujimura, Norio; Yoshida, Tadayoshi

2006-01-01

The Japan Atomic Energy Agency (JAEA), Nuclear Fuel Cycle Engineering Laboratories, operates a spent fuel reprocessing plant and MOX (Plutonium-Uranium Mixed Oxide) fuel fabrication plants. Criticality accident detectors have been installed in these facilities. The detector, the Toshiba RD120, is composed of a plastic scintillator coupled to a photomultiplier tube, and an operational amplifier. The alarm triggering point is set to 1.0-3.6 mGy·h -1 in photon dose rate to detect the minimum accident of concern. However, a plastic scintillator is principally sensitive not only to primary photons but also to neutrons by secondary photons and heavy charged particles produced in the detector itself. The authors calculated energy and angular responses of the RD120 criticality accident detector to photons and neutrons using Monte Carlo computer codes. The response to primary photons was evaluated with the MCNP-4B and EGS4 calculations, and photon and X-ray irradiation experiments. The response to neutrons that produce secondary photons and heavy charged particles from neutron interactions was computed using the MCNP-4B and SCINFUL, respectively. As a result, reliable response functions were obtained. These results will be a great help in reassessing the coverage area and in determining the appropriate triggering dose rate level in criticality accidents. (author)

Process criticality accident likelihoods, consequences, and emergency planning

Energy Technology Data Exchange (ETDEWEB)

McLaughlin, T.P.

1991-01-01

Evaluation of criticality accident risks in the processing of significant quantities of fissile materials is both complex and subjective, largely due to the lack of accident statistics. Thus, complying with standards such as ISO 7753 which mandates that the need for an alarm system be evaluated, is also subjective. A review of guidance found in the literature on potential accident magnitudes is presented for different material forms and arrangements. Reasoned arguments are also presented concerning accident prevention and accident likelihoods for these material forms and arrangements. 13 refs., 1 fig., 1 tab.

Plant safety review from mass criticality accident

International Nuclear Information System (INIS)

Susanto, B.G.

2000-01-01

The review has been done to understand the resent status of the plant in facing postulated mass criticality accident. From the design concept of the plant all the components in the system including functional groups have been designed based on favorable mass/geometry safety principle. The criticality safety for each component is guaranteed because all the dimensions relevant to criticality of the components are smaller than dimensions of 'favorable mass/geometry'. The procedures covering all aspects affecting quality including the safety related are developed and adhered to at all times. Staff are indoctrinated periodically in short training session to warn the important of the safety in process of production. The plant is fully equipped with 6 (six) criticality detectors in strategic places to alert employees whenever the postulated mass criticality accident occur. In the event of Nuclear Emergency Preparedness, PT BATAN TEKNOLOGI has also proposed the organization structure how promptly to report the crisis to Nuclear Energy Control Board (BAPETEN) Indonesia. (author)

Cognitive systems engineering analysis of the JCO criticality accident

International Nuclear Information System (INIS)

Tanabe, Fumiya; Yamaguchi, Yukichi

2000-01-01

The JCO Criticality Accident is analyzed with a framework based on cognitive systems engineering. With the framework, analysis is conducted integrally both from the system viewpoint and actors viewpoint. The occupational chemical risk was important as safety constraint for the actors as well as the nuclear risk, which is due to criticality accident, to the public and to actors. The inappropriate actor's mental model of the work system played a critical role and several factors (e.g. poor training and education, lack of information on criticality safety control in the procedures and instructions, and lack of warning signs at workplace) contributed to form and shape the mental model. Based on the analysis, several countermeasures, such as warning signs, information system for supporting actors and improved training and education, are derived to prevent such an accident. (author)

Review of design criteria for Criticality Accident Alarm System (CAAS) used in Fuel Reprocessing Facility

International Nuclear Information System (INIS)

Chandrasekaran, S.; Basu, Pew; Sivasubramaniyan, K.; Venkatraman, B.

2016-01-01

Though fuel cycle facilities handling fissile materials are designed with careful criticality safety analysis, the criticality accident cannot be ruled out completely. Criticality Accident Alarm System (CAAS) is being installed as part of criticality safety management in fuel cycle facilities. CAAS system being used in India, is ECIL make, ionization chamber based gamma detector, which houses three identical detectors and works on 2/3 logic. As per ISO 7753 and ANSI/ANS-8.3, the CAAS must be designed to be capable of detecting any minimum accident occurs which could be of concern. Based on this, alarm limit used in CAAS is: 4 R/h (fast transient excursion) and 3 mR in 0.5 sec (slow excursion). In case of reprocessing facilities wherein process tanks located in heavy shielding, identification of CAAS installation locations require detailed radiation transport calculations. A study has been taken to estimate the gamma dose rate from thick concrete hot cells in order to determine the locations of CAAS to meet the present design criteria of alarm limit

Prevention of the causes and consequences of a criticality accident - measures adopted in France; Prevention des causes et des consequences d'un accident de criticite - solutions adoptees en France

Energy Technology Data Exchange (ETDEWEB)

Fruchard, Y; Lavie, J M

1966-07-01

The question of safety in regard to criticality accident risks has two aspects: prevention of the cause and limitation of the consequences. These two aspects are closely connected. The effort devoted to prevention of the causes depends on the seriousness of the possible human psychologic and economic consequences of the accident. The criticality accidents which have occurred in the nuclear industry, though few in number, do reveal the imperfect nature of the techniques adopted to prevent the causes, and also constitute the only available realistic basis for evaluating the consequences and developing measures to limit them. The authors give a analysis of the known causes and consequences of past criticality accidents and on this basis make a number of comments concerning: the validity of traditional safety criteria, the probability of accidents for different types of operations, characteristic accidents which can serve as models, and the extent of possible radiological consequences. The measures adopted in France to limit the consequences of a possible criticality accident under the headings: location, design and lay-out of the installations, accident detection, and dosimetry for the exposed personnel, are briefly described after a short account of the criteria used in deciding on them. (author) [French] La surete relative aux risques d'accidents de criticite presente deux aspects: la prevention des causes et les parades aux consequences. Ces deux aspects sont tres lies. L'effort consenti a la prevention des causes decoule de l'importance des consequences humaines economiques et psychologiques possibles d'un eventuel accident. Les accidents de criticite survenus dans l'industrie nucleaire, malgre leur rarete, d'une part devoilent les imperfections des techniques de prevention des causes, d'autre part constituent la seule base realiste disponible d'evaluation des consequences et de mise au point des parades a ces consequences. Les auteurs presentent une analyse des

Comparison of the dose evaluation methods for criticality accident

International Nuclear Information System (INIS)

Shimizu, Yoshio; Oka, Tsutomu

2004-01-01

The improvement of the dose evaluation method for criticality accidents is important to rationalize design of the nuclear fuel cycle facilities. The source spectrums of neutron and gamma ray of a criticality accident depend on the condition of the source, its materials, moderation, density and so on. The comparison of the dose evaluation methods for a criticality accident is made. Some methods, which are combination of criticality calculation and shielding calculation, are proposed. Prompt neutron and gamma ray doses from nuclear criticality of some uranium systems have been evaluated as the Nuclear Criticality Slide Rule. The uranium metal source (unmoderated system) and the uranyl nitrate solution source (moderated system) in the rule are evaluated by some calculation methods, which are combinations of code and cross section library, as follows: (a) SAS1X (ENDF/B-IV), (b) MCNP4C (ENDF/B-VI)-ANISN (DLC23E or JSD120), (c) MCNP4C-MCNP4C (ENDF/B-VI). They have consisted of criticality calculation and shielding calculation. These calculation methods are compared about the tissue absorbed dose and the spectrums at 2 m from the source. (author)

Detection device for off-gas system accidents

International Nuclear Information System (INIS)

Kubota, Ryuji; Tsuruoka, Ryozo; Yamanari, Shozo.

1984-01-01

Purpose: To rapidly isolate the off-gas system by detecting the off-gas system failure accident in a short time. Constitution: Radiation monitors are disposed to ducts connecting an exhaust gas area and an air conditioning system as a portion of a turbine building. The ducts are disposed independently such that they ventilate only the atmosphere in the exhaust gas area and do not mix the atmosphere in the turbine building. Since radioactivity issued upon off-gas accidents to the exhaust gas area is sucked to the duct, it can be detected by radiation detection monitors in a short time after the accident. Further, since the operator judges it as the off-gas system accident, the off-gas system can be isolated in a short time after the accident. (Moriyama, K.)

Detection and analysis of accident black spots with even small accident figures.

NARCIS (Netherlands)

Oppe, S.

1982-01-01

Accident black spots are usually defined as road locations with high accident potentials. In order to detect such hazardous locations we have to know the probability of an accident for a traffic situation of some kind, or the mean number of accidents for some unit of time. In almost all procedures

Program for rapid dose assessment in criticality accident, RADAPAS

International Nuclear Information System (INIS)

Takahashi, Fumiaki

2006-09-01

In a criticality accident, a person near fissile material can receive extremely high dose which can cause acute health effect. For such a case, medical treatment should be carried out for the exposed person, according to severity of the exposure. Then, radiation dose should be rapidly assessed soon after an outbreak of an accident. Dose assessment based upon the quantity of induced 24 Na in human body through neutron exposure is expected as one of useful dosimetry techniques in a criticality accident. A dose assessment program, called RADAPAS (RApid Dose Assessment Program from Activated Sodium in Criticality Accidents), was therefore developed to assess rapidly radiation dose to exposed persons from activity of induced 24 Na. RADAPAS consists of two parts; one is a database part and the other is a part for execution of dose calculation. The database contains data compendiums of energy spectra and dose conversion coefficients from specific activity of 24 Na induced in human body, which had been derived in a previous analysis using Monte Carlo calculation code. Information for criticality configuration or characteristics of radiation in the accident field is to be interactively given with interface displays in the dose calculation. RADAPAS can rapidly derive radiation dose to the exposed person from the given information and measured 24 Na specific activity by using the conversion coefficient in database. This report describes data for dose conversions and dose calculation in RADAPAS and explains how to use the program. (author)

Prevention of the causes and consequences of a criticality accident - measures adopted in France; Prevention des causes et des consequences d'un accident de criticite - solutions adoptees en France

Energy Technology Data Exchange (ETDEWEB)

Fruchard, Y.; Lavie, J.M

1966-07-01

The question of safety in regard to criticality accident risks has two aspects: prevention of the cause and limitation of the consequences. These two aspects are closely connected. The effort devoted to prevention of the causes depends on the seriousness of the possible human psychologic and economic consequences of the accident. The criticality accidents which have occurred in the nuclear industry, though few in number, do reveal the imperfect nature of the techniques adopted to prevent the causes, and also constitute the only available realistic basis for evaluating the consequences and developing measures to limit them. The authors give a analysis of the known causes and consequences of past criticality accidents and on this basis make a number of comments concerning: the validity of traditional safety criteria, the probability of accidents for different types of operations, characteristic accidents which can serve as models, and the extent of possible radiological consequences. The measures adopted in France to limit the consequences of a possible criticality accident under the headings: location, design and lay-out of the installations, accident detection, and dosimetry for the exposed personnel, are briefly described after a short account of the criteria used in deciding on them. (author) [French] La surete relative aux risques d'accidents de criticite presente deux aspects: la prevention des causes et les parades aux consequences. Ces deux aspects sont tres lies. L'effort consenti a la prevention des causes decoule de l'importance des consequences humaines economiques et psychologiques possibles d'un eventuel accident. Les accidents de criticite survenus dans l'industrie nucleaire, malgre leur rarete, d'une part devoilent les imperfections des techniques de prevention des causes, d'autre part constituent la seule base realiste disponible d'evaluation des consequences et de mise au point des parades a ces consequences

Bayesian methods for chromosome dosimetry following a criticality accident

International Nuclear Information System (INIS)

Brame, R.S.; Groer, P.G.

2003-01-01

Radiation doses received during a criticality accident will be from a combination of fission spectrum neutrons and gamma rays. It is desirable to estimate the total dose, as well as the neutron and gamma doses. Present methods for dose estimation with chromosome aberrations after a criticality accident use point estimates of the neutron to gamma dose ratio obtained from personnel dosemeters and/or accident reconstruction calculations. In this paper a Bayesian approach to dose estimation with chromosome aberrations is developed that allows the uncertainty of the dose ratio to be considered. Posterior probability densities for the total and the neutron and gamma doses were derived. (author)

Applicability of simplified methods to evaluate consequences of criticality accident using past accident data

International Nuclear Information System (INIS)

Nakajima, Ken

2003-01-01

Applicability of four simplified methods to evaluate the consequences of criticality accident was investigated. Fissions in the initial burst and total fissions were evaluated using the simplified methods and those results were compared with the past accident data. The simplified methods give the number of fissions in the initial burst as a function of solution volume; however the accident data did not show such tendency. This would be caused by the lack of accident data for the initial burst with high accuracy. For total fissions, simplified almost reproduced the upper envelope of the accidents. However several accidents, which were beyond the applicable conditions, resulted in the larger total fissions than the evaluations. In particular, the Tokai-mura accident in 1999 gave in the largest total specific fissions, because the activation of cooling system brought the relatively high power for a long time. (author)

Prevention of the Causes and Consequences of Criticality Accidents: Measures Adopted in France; Prevention des Causes et des Consequences d'un Accident de Criticite: Solutions Adoptees en France

Energy Technology Data Exchange (ETDEWEB)

Fruchard, Y.; Lavie, J. -M. [Commissariat a l' Energie Atomique, Paris (France)

1966-05-15

It is important to guard against the risk of criticality accidents by seeking to prevent their occurrence through the elimination of their causes and also by taking steps to provide against their consequences. These two aspects are closely linked since the efforts made to elaborate preventive procedures are dictated by the importance of the repercussions which such accidents are liable to have in the human, economic and psychological spheres. The criticality accidents which have occurred in the nuclear industry, though small in number, do reveal the imperfect nature of the techniques adopted to prevent them, and they constitute the only available realistic basis for evaluating their consequences and developing suitable precautionary techniques. The authors give a detailed analysis of the known causes and consequences of past criticality accidents and on this basis make a number of comments in connection with the validity of traditional safety criteria, the probability of accidents for different types of operation, the characteristic accidents capable of serving as models, and the extent of possible radiological consequences. The measures adopted in France to limit the consequences of a possible criticality accident (location, design and lay-out of installations, accident detection dosimetry for exposed personnel) are briefly described after a short account of the criteria used in deciding on them. Finally, the authors discuss the economic implications of adopting particular precautionary measures and of applying them uniformly, taking due account of the question of reliability. (author) [French] II est important de se proteger contre les risques d'accidents de criticite en tentant, d'une part, de prevenir les accidents eux-memes par l'elimination de leurs causes, d'autre part, de parer a leurs consequences. Ces deux aspects sont tres lies: l'effort portant sur la prevention des accidents decoule de l'importance de leurs consequences sur les plans humain, economique

Evaluation of coverage of enriched UF6 cylinder storage lots by existing criticality accident alarms

International Nuclear Information System (INIS)

Lee, B.L. Jr.; Dobelbower, M.C.; Woollard, J.E.; Sutherland, P.J.; Tayloe, R.W. Jr.

1995-03-01

The Portsmouth Gaseous Diffusion Plant (PORTS) is leased from the US Department of Energy (DOE) by the United States Enrichment Corporation (USEC), a government corporation formed in 1993. PORTS is in transition from regulation by DOE to regulation by the Nuclear Regulatory Commission (NRC). One regulation is 10 CFR Part 76.89, which requires that criticality alarm systems be provided for the site. PORTS originally installed criticality accident alarm systems in all building for which nuclear criticality accidents were credible. Currently, however, alarm systems are not installed in the enriched uranium hexafluoride (UF 6 ) cylinder storage lots. This report analyzes and documents the extent to which enriched UF 6 cylinder storage lots at PORTS are covered by criticality detectors and alarms currently installed in adjacent buildings. Monte Carlo calculations are performed on simplified models of the cylinder storage lots and adjacent buildings. The storage lots modelled are X-745B, X-745C, X745D, X-745E, and X-745F. The criticality detectors modelled are located in building X-343, the building X-344A/X-342A complex, and portions of building X-330 (see Figures 1 and 2). These criticality detectors are those located closest to the cylinder storage lots. Results of this analysis indicate that the existing criticality detectors currently installed at PORTS are largely ineffective in detecting neutron radiation from criticality accidents in most of the cylinder storage lots at PORTS, except sometimes along portions of their peripheries

A criticism of ANSI/ANS-8.3-1986: Criticality accident alarm system

International Nuclear Information System (INIS)

Malenfant, R.E.

1991-01-01

The American National Standard on criticality accident alarm systems has given rise to confusion in interpretation and implementation of the requirements. In addition, some of the standards have recently been incorporated into US Department of Energy (DOE) orders, and others have been paraphrased in the DOE orders. Some of the DOE orders referencing these standards are being incorporated into law by means of the Code of Federal Regulations. As such, the intent of the authors of the standards to recommend a code of good practice is now being codified into law with attendant civil and criminal penalties for failure to comply. It is suggested that ANSI/ANS-8.3-1986, Critically Accident Alarm System, be carefully reviewed to alleviate the confusion that has been experienced in practice, to clarify the minimum accident of concern, to further define the dose (or dose rate) criteria for activation, and to stress the fact that a prime consideration in any safety system is the overall reduction of risk

Review and compilation of criticality accidents in nuclear fuel processing facilities outside of Japan

International Nuclear Information System (INIS)

Watanabe, Norio; Tamaki, Hitoshi

2000-04-01

On September 30, 1999, a criticality accident occurred at the Tokai-mura uranium processing plant operated by JCO Co., Ltd., which resulted in the first nuclear accident involving a fatality, in Japan, and forced the residents in the vicinity of the site to be evacuated and be sheltered indoors. There have now been 21 criticality accidents reported in nuclear fuel processing facilities in foreign countries: seven in the United States, one in the United Kingdom and thirteen in Russia. Most of them occurred during the period from mid-1950's to mid-1960's, but one criticality accident tool place in Russian in 1997. This report reviews and compiles the published information on these accidents, including the latest information, focusing on the event sequence, the consequence of accident, and the cause of accident. The observations from the reviews are summarized as follows: Twenty of the 21 accidents occurred with the fissile material in a liquid. Twenty of the 21 accidents occurred in vessels/tanks with unfavorable geometry but one occurred in the vessel with favorable geometry. There were seven fatalities that were involved in five accidents. Three accidents involved a re-criticality condition caused by inadequate operator actions and two of them led to the death of the operators. One accident reached a re-criticality condition several hours after the first excursion was terminated by injecting borated water into the affected vessel. This accident implies the possibility that the borated water injection might not be effective to the criticality termination due to solubility of boric acid. Mechanisms of the criticality termination vary as follows: ejection or splashing of the solution at the time of power excursion, boiling or evaporation, addition of neutron poisons, or manual draining of solutions. (author)

Review and compilation of criticality accidents in nuclear fuel processing facilities outside of Japan

Energy Technology Data Exchange (ETDEWEB)

Watanabe, Norio [Planning and Analysis Division, Nuclear Safety Research Center, Tokai Research Establishment, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan); Tamaki, Hitoshi [Department of Safety Research Technical Support, Tokai Research Establishment, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan)

2000-04-01

On September 30, 1999, a criticality accident occurred at the Tokai-mura uranium processing plant operated by JCO Co., Ltd., which resulted in the first nuclear accident involving a fatality, in Japan, and forced the residents in the vicinity of the site to be evacuated and be sheltered indoors. There have now been 21 criticality accidents reported in nuclear fuel processing facilities in foreign countries: seven in the United States, one in the United Kingdom and thirteen in Russia. Most of them occurred during the period from mid-1950's to mid-1960's, but one criticality accident tool place in Russian in 1997. This report reviews and compiles the published information on these accidents, including the latest information, focusing on the event sequence, the consequence of accident, and the cause of accident. The observations from the reviews are summarized as follows: Twenty of the 21 accidents occurred with the fissile material in a liquid. Twenty of the 21 accidents occurred in vessels/tanks with unfavorable geometry but one occurred in the vessel with favorable geometry. There were seven fatalities that were involved in five accidents. Three accidents involved a re-criticality condition caused by inadequate operator actions and two of them led to the death of the operators. One accident reached a re-criticality condition several hours after the first excursion was terminated by injecting borated water into the affected vessel. This accident implies the possibility that the borated water injection might not be effective to the criticality termination due to solubility of boric acid. Mechanisms of the criticality termination vary as follows: ejection or splashing of the solution at the time of power excursion, boiling or evaporation, addition of neutron poisons, or manual draining of solutions. (author)

An analysis on human factor issues in criticality accident at a uranium processing plant. Investigation on human behavior contributing to the criticality accident. Interim report

International Nuclear Information System (INIS)

Sasou, Kuonihide; Goda, Hideki; Hirotsu, Yuko

1999-01-01

At 10:30 am, September 30th, 1999, a criticality accident occurred in a conversion building of a uranium processing plant in Tokai, Ibaraki prefecture. 69 people including 3 workers who then worked at the building, 3 fire fighters who dispatched to rescue them were exposed to the radiation. People with a 350 m-radius of the site were recommended to evacuate themselves from the region to a temporarily prepared evacuation center. And about one hundred thousand people within a 10 km-radius were also advised to stay inside of their home. Nuclear Safety Commission's Accident Investigation Committee is investigating causes of this accident and have been revealing that deviation from government-authorized processing method and negligence of its illegal procedure had contributed to the accident. The influence of this accident is expanding not only to the plant operating company, local people but also to Japanese nuclear power policy, the whole nuclear industry in Japan. Especially pervasion of 'Safety Culture' is strongly being required. This report analyses latent factors of some human behavior directly contributing to the criticality accident. It also mentions that 4 critical points on the poor climate for safety in the work place, the inadequate safety management, the unsuitable equipment and the production-biased company's policy are the latent factors of this accident. It also finds that the poor climate and the production-biased policy are the most important factors. It can be said that some people directly or indirectly having caused the accident are the victims of them. (author)

The criticality accident in Tokaimura and medical aspects of radiation emergency

International Nuclear Information System (INIS)

Chen Xiaohua; Mao Bingzhi

2003-01-01

A criticality accident occurred on September 30, 1999 at the uranium processing plant in Tokaimura Japan, which is the most severe accident since Chernobyl catastrophe. 213 people were exposed to radiation, among them 2 workers were exposed to 16-23 Gy and 6-10 Gy individually, one worker was 2 Gy, 2 people was 10 mSv and 208 person was 0-5 mSv. Author was invited to attend an international symposium on 'The Criticality Accident in Tokaimura Medical Aspects of Radiation Emergency' in Chiba Japan on December 2000. An overview of the accident, dose estimation and neutron relative biological effects are discussed in this article

A Review of Criticality Accidents 2000 Revision

Energy Technology Data Exchange (ETDEWEB)

Thomas P. McLaughlin; Shean P. Monahan; Norman L. Pruvost; Vladimir V. Frolov; Boris G. Ryazanov; Victor I. Sviridov

2000-05-01

Criticality accidents and the characteristics of prompt power excursions are discussed. Sixty accidental power excursions are reviewed. Sufficient detail is provided to enable the reader to understand the physical situation, the chemistry and material flow, and when available the administrative setting leading up to the time of the accident. Information on the power history, energy release, consequences, and causes are also included when available. For those accidents that occurred in process plants, two new sections have been included in this revision. The first is an analysis and summary of the physical and neutronic features of the chain reacting systems. The second is a compilation of observations and lessons learned. Excursions associated with large power reactors are not included in this report.

A Review of Criticality Accidents 2000 Revision

International Nuclear Information System (INIS)

McLaughlin, Thomas P.; Monahan, Shean P.; Pruvost, Norman L.; Frolov, Vladimir V.; Ryazanov, Boris G.; Sviridov, Victor I.

2000-01-01

Criticality accidents and the characteristics of prompt power excursions are discussed. Sixty accidental power excursions are reviewed. Sufficient detail is provided to enable the reader to understand the physical situation, the chemistry and material flow, and when available the administrative setting leading up to the time of the accident. Information on the power history, energy release, consequences, and causes are also included when available. For those accidents that occurred in process plants, two new sections have been included in this revision. The first is an analysis and summary of the physical and neutronic features of the chain reacting systems. The second is a compilation of observations and lessons learned. Excursions associated with large power reactors are not included in this report

Installation places of criticality accident detectors in the plutonium conversion development facility

International Nuclear Information System (INIS)

Sanada, Yukihisa; Tsujimura, Norio; Shimizu, Yoshio; Izaki, Kenji; Furuta, Sadaaki

2008-01-01

At the Plutonium Conversion Development Facility (PCDF) in the Nuclear Fuel Cycle Engineering Laboratories, the co-conversion technologies to purify the mixed plutonium and uranium nitrate solution discharged from a reprocessing plant have been developed. The probability of a criticality accident in PCDF is extremely low. However, the criticality accident alarm system (CAAS) has been in place since 1982 to reduce the radiation dose to workers in case of such a rare criticality accident. The CAAS contains criticality accident detector units (CADs), one unit consisting of three plastic scintillation detectors, and using the 2 out of 3 voting system for the purpose of high reliability. Currently, eight CADs are installed in PCDF evaluating the dose using a simple equation allowing for a safety margin. The purpose of this study is to show the determination procedures for the adequate relocation of the CADs which adequately ensures safety in PCDF. (author)

Part 1: The detection of criticality accidents in the Commissariat a l'Energie Atomique. Part 2: The Burst Slug Detection; 1. partie: la detection des accidents de criticite au Commissariat a l'Energie Atomique. 2. partie.: la detection des ruptures de gaines

Energy Technology Data Exchange (ETDEWEB)

Debrie, G; Lavie, J; Planque, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

In all installations where fissionable materials are handled in quantities virtually greater than the critical mass, there exists permanent risk of accidental nuclear excursion entailing a serious irradiation hazard to the personnel, in spite of all the precautions that might be taken. Immediate detection followed by rapid evacuation greatly limits the risks of irradiation due to the fission products or to the sustained nuclear reaction. The necessity for a suitable equipment for the detection of accidents of criticality is imposed by the fact that the physical phenomena accompanying a nuclear, excursion are insufficient to follow the alarm, and may lead to confusion. Taking into account the accidents which have occurred and the role expected from a detector, we choose a dose integration device for the detecting probe proper, and a system based on the coincidence of several information to trigger the alarm. At the demand of the Commission des Masses Critiques, the minimal physical and electronic features required to obtain a very reliable system with minimal risk of false alarm has been established. These features are described in some detail. The equipment constructed at the Commissariat a l'Energie Atomique on the basis of these recommendations has been tested systematically under actual conditions of nuclear excursions at the Health Physics Research Reactor of the National Laboratory at Oak Ridge. These tests have served to determine two types of detection probes which will be described: a photomultiplier and a semiconductor probe. Finally the authors present an example of a complete unit for the detection of criticality accidents in an installation for the processing of fissile material. B - The evolution of the installations for burst slug detection (BSD) in french reactors. The main part of the effort in the field of the Burst Slug Detection has been orientated on the large gas-cooled reactors where the problem of bursts slugs is associated with the economics

Criticality accident dosimetry with ESR spectroscopy.

Science.gov (United States)

d'Errico, F; Fattibene, P; Onori, S; Pantaloni, M

1996-01-01

The suitability of the ESR alanine and sugar detectors for criticality accident dosimetry was experimentally investigated during an intercomparison of dosimetry techniques. Tests were performed irradiating detectors both free-in-air and on-phantom during controlled critcality excursions at the SILENE reactor in Valduc, France. Several grays of absorbed dose were imparted in neutron gamma-ray fields of various relative intensities and spectral distributions. Analysed results confirmed the potential of these systems which can immediately provide an acute dose assessment with an average underestimate of 30%in the various fields. This performance allows for the screening of severely exposed individuals and meets the IAEA recommendations on the early estimate of accident absorbed doses.

PNNL Results from 2010 CALIBAN Criticality Accident Dosimeter Intercomparison Exercise

International Nuclear Information System (INIS)

Hill, Robin L.; Conrady, Matthew M.

2011-01-01

This document reports the results of the Hanford personnel nuclear accident dosimeter (PNAD) and fixed nuclear accident dosimeter (FNAD) during a criticality accident dosimeter intercomparison exercise at the CEA Valduc Center on September 20-23, 2010. Pacific Northwest National Laboratory (PNNL) participated in a criticality accident dosimeter intercomparison exercise at the Commissariat a Energie Atomique (CEA) Valduc Center near Dijon, France on September 20-23, 2010. The intercomparison exercise was funded by the U.S. Department of Energy, Nuclear Criticality Safety Program, with Lawrence Livermore National Laboratory as the lead Laboratory. PNNL was one of six invited DOE Laboratory participants. The other participating Laboratories were: Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), Savannah River Site (SRS), the Y-12 National Security Complex at Oak Ridge, and Sandia National Laboratory (SNL). The goals of PNNL's participation in the intercomparison exercise were to test and validate the procedures and algorithm currently used for the Hanford personnel nuclear accident dosimeters (PNADs) on the metallic reactor, CALIBAN, to test exposures to PNADs from the side and from behind a phantom, and to test PNADs that were taken from a historical batch of Hanford PNADs that had varying degrees of degradation of the bare indium foil. Similar testing of the PNADs was done on the Valduc SILENE test reactor in 2009 (Hill and Conrady, 2010). The CALIBAN results are reported here.

Development of INCTAC code for analyzing criticality accident phenomena

International Nuclear Information System (INIS)

Mitake, Susumu; Hayashi, Yamato; Sakurai, Shungo

2003-01-01

Aiming at understanding nuclear transients and thermal- and hydraulic-phenomena of the criticality accident, a code named INCTAC has been newly developed at the Institute of Nuclear Safety. The code is applicable to the analysis of criticality accident transients of aqueous homogenous fuel solution system. Neutronic transient model is composed of equations for the kinetics and for the spatial distributions, which are deduced from the time dependent multi-group transport equations with the quasi steady state assumption. Thermal-hydraulic transient model is composed of a complete set of the mass, momentum and energy equations together with the two-phase flow assumptions. Validation tests of INCTAC were made using the data obtained at TRACY, a transient experiment criticality facility of JAERI. The calculated results with INCTAC showed a very good agreement with the experiment data, except a slight discrepancy of the time when the peak of reactor power was attained. But, the discrepancy was resolved with the use of an adequate model for movement and transfer of the void in the fuel solution mostly generated by radiolysis. With a simulation model for the transport of radioactive materials through ventilation systems to the environment, INCTAC will be used as an overall safety evaluation code of the criticality accident. (author)

Prevention of criticality accidents in a fuel cycle plant

International Nuclear Information System (INIS)

Gatti, A.M.; Canavese, S.I.; Capadona, N.M.

1990-01-01

This work reports the basic considerations on criticality accidents applied to an uranium dioxide fuel cycle production plant. The different fabrication stages are briefly described, with the identification of the neutronically isolated areas. Once the areas have been defined, an evaluation is made, setting up the control parameters to be used in each of them and their variation ranges; normal operation limitations based on experimental data or validating calculations, applied specifically to 5% enriched uranium, are established. Afterwards, defined parameters deviations are analyzed due to incidental conditions in order to prevent criticality accidents under normal conditions and maintenance operations. (Author) [es

A Review of Accident Modelling Approaches for Complex Critical Sociotechnical Systems

National Research Council Canada - National Science Library

Qureshi, Zahid H

2008-01-01

.... This report provides a review of key traditional accident modelling approaches and their limitations, and describes new system-theoretic approaches to the modelling and analysis of accidents in safety-critical systems...

Modeling of criticality accidents and their environmental consequences

International Nuclear Information System (INIS)

Thomas, W.; Gmal, B.

1987-01-01

In the Federal Republic of Germany, potential radiological consequences of accidental nuclear criticality have to be evaluated in the licensing procedure for fuel cycle facilities. A prerequisite to this evaluation is to establish conceivable accident scenarios. First, possibilities for a criticality exceeding the generally applied double contingency principle of safety are identified by screening the equipment and operation of the facility. Identification of undetected accumulations of fissile material or incorrect transfer of fissile solution to unfavorable geometry normally are most important. Second, relevant and credible scenarios causing the most severe consequences are derived from these possibilities. For the identified relevant scenarios, time-dependent fission rates and reasonable numbers for peak power and total fissions must be determined. Experience from real accidents and experiments (KEWB, SPERT, CRAC, SILENE) has been evaluated using empirical formulas. To model the time-dependent behavior of criticality excursions in fissile solutions, a computer program FELIX has been developed

Characteristics of the French system for the detection of criticity accidents

International Nuclear Information System (INIS)

Barbry, F.; Prigent, R.

1983-01-01

The first versions of these devices were put in operation in the industry during 1976, i.e., more than 10 years after the very first criticity detection and warning systems in France. Today some 350 probes are installed

Development of likelihood estimation method for criticality accidents of mixed oxide fuel fabrication facilities

International Nuclear Information System (INIS)

Tamaki, Hitoshi; Yoshida, Kazuo; Kimoto, Tatsuya; Hamaguchi, Yoshikane

2010-01-01

A criticality accident in a MOX fuel fabrication facility may occur depending on several parameters, such as mass inventory and plutonium enrichment. MOX handling units in the facility are designed and operated based on the double contingency principle to prevent criticality accidents. Control failures of at least two parameters are needed for the occurrence of criticality accident. To evaluate the probability of such control failures, the criticality conditions of each parameter for a specific handling unit are necessary for accident scenario analysis to be clarified quantitatively with a criticality analysis computer code. In addition to this issue, a computer-based control system for mass inventory is planned to be installed into MOX handling equipment in a commercial MOX fuel fabrication plant. The reliability analysis is another important issue in evaluating the likelihood of control failure caused by software malfunction. A likelihood estimation method for criticality accident has been developed with these issues been taken into consideration. In this paper, an example of analysis with the proposed method and the applicability of the method are also shown through a trial application to a model MOX fabrication facility. (author)

Theoretical Derivation of Simplified Evaluation Models for the First Peak of a Criticality Accident in Nuclear Fuel Solution

International Nuclear Information System (INIS)

Nomura, Yasushi

2000-01-01

In a reprocessing facility where nuclear fuel solutions are processed, one could observe a series of power peaks, with the highest peak right after a criticality accident. The criticality alarm system (CAS) is designed to detect the first power peak and warn workers near the reacting material by sounding alarms immediately. Consequently, exposure of the workers would be minimized by an immediate and effective evacuation. Therefore, in the design and installation of a CAS, it is necessary to estimate the magnitude of the first power peak and to set up the threshold point where the CAS initiates the alarm. Furthermore, it is necessary to estimate the level of potential exposure of workers in the case of accidents so as to decide the appropriateness of installing a CAS for a given compartment.A simplified evaluation model to estimate the minimum scale of the first power peak during a criticality accident is derived by theoretical considerations only for use in the design of a CAS to set up the threshold point triggering the alarm signal. Another simplified evaluation model is derived in the same way to estimate the maximum scale of the first power peak for use in judging the appropriateness for installing a CAS. Both models are shown to have adequate margin in predicting the minimum and maximum scale of criticality accidents by comparing their results with French CRiticality occurring ACcidentally (CRAC) experimental data

State of reaction on news media for JCO criticality accident on abroad

International Nuclear Information System (INIS)

Itoh, Takeshi

1999-01-01

The criticality accident, which occurred in JCO Tokai on September 30th 1999, was the first accident accompanied with serious radiation exposure to persons at Japanese nuclear facilities. As an evacuation order for local residents was issued, it caused uneasiness to the public. It also gave great impact to the foreign countries. In this report we have investigated the reactions in such countries, as U.S., France, Germany and U.K. by means of news media like TV, newspapers and magazines. Finding are as follows: They were all surprised to know the cause of the accident, which was by improper procedure of JCO workers. Because they couldn't imagine that such an accident might happen in such a high-tech country as Japan. The Japanese regulator was criticized for their insufficient criticality facility surveillance. There arose some questions for Japanese nuclear reliabilities. Because of the delayed announcement of the accident by Japanese public sector, anti-nuclear groups, like Greenpeace, NCI, etc., have a chance to carry on their campaign. The information from Japanese public sector was not enough to satisfy the foreign news media. We concluded that it is also necessary to develop effective information dissemination to overseas in case of a nuclear accident. (author)

Analysis and evaluation of the nuclear criticality accident in JCO CO. LTD in Japan

International Nuclear Information System (INIS)

Liu Hua; Liu Xinhua; Li Bing

2001-01-01

The author describes JCO criticality accident situation including the background, process chronology and emergency countermeasures taken of the accident and its radiation consequence. The analysis about the direct and root causes of the accident and some conclusions are also showed. The direct cause of the accident is the use of geometrically unsafe process equipment and personnel violation. However, the root cause is lack of efficient technical management. Therefore, it is necessary to emphasize the criticality safety in nuclear fuel cycle installations and enhance safety culture of regulatory and operational personnel

ANSI/ANS-8.23-1997: nuclear criticality accident emergency planning and response

International Nuclear Information System (INIS)

Baker, J.S.

2004-01-01

American National Standard ANSUANS-8.23 was developed to expand upon the basic emergency response guidance given in American National Standard, 'Administrative Practices for Nuclear Criticality Safety' ANSI/ANS-8.19-1996 (Ref. 1). This standard provides guidance for minimizing risks to personnel during emergency response to a nuclear criticality accident outside reactors. This standard is intended to apply to those facilities for which a criticality accident alarm system, as specified in American National Standard, 'Criticality Accident Alarm System', ANSI/ANS-8.3-1997 (Ref. 2) is in use. The Working Group was established in 1990, with Norman L. Pruvost as chairman. The Working Group had up to twenty-three members representing a broad range of the nuclear industry, and has included members from Canada, Japan and the United Kingdom. The initial edition of ANSI/ANS-8.23 was approved by the American National Standards Institute on December 30, 1997. It provides guidance for the following topics: (1) Management and technical staff responsibilities; (2) Evaluation of a potential criticality accident; (3) Emergency plan provisions; (4) Evacuation; (5) Re-entry, rescue and stabilization; and (6) Classroom training, exercises and evacuation drills. This guidance is not for generic emergency planning issues, but is specific to nuclear criticality accidents. For example, it assumes that an Emergency Plan is already established at facilities that implement the standard. During the development of the initial edition of ANSI/ANS-8.23, each Working Group member evaluated potential use of the standard at a facility with which the member was familiar. This revealed areas where a facility could have difficulty complying with the standard. These reviews helped identify and eliminate many potential problems and ambiguities with the guidance. The Working Group has received very limited feedback from the user community since the first edition of the standard was published. Suggestions

JCO criticality accident as POST-LOCA: Poor structure induced loss of organizational control accident

International Nuclear Information System (INIS)

Furuhama, Yutaka

2000-01-01

Some problems in operation and business management of JCO (Japan Nuclear Fuel Conversion Co.) have been studied as background factors of the criticality accident. Open information about business conditions of JCO suggests that the cause of the accident is not so simple as to be attributed only to economic pressure, but includes immanent problems in JCO. We investigate the problems from five viewpoints, organization of safety management, system of operation management, activities for business improvement, risk awareness, and restructuring of business, and discuss the effects and causality of background factors as well as remedies for them. (author)

A neutron dosemeter for nuclear criticality accidents.

Science.gov (United States)

d'Errico, F; Curzio, G; Ciolini, R; Del Gratta, A; Nath, R

2004-01-01

A neutron dosemeter which offers instant read-out has been developed for nuclear criticality accidents. The system is based on gels containing emulsions of superheated dichlorodifluoromethane droplets, which vaporise into bubbles upon neutron irradiation. The expansion of these bubbles displaces an equivalent volume of gel into a graduated pipette, providing an immediate measure of the dose. Instant read-out is achieved using an array of transmissive optical sensors which consist of coupled LED emitters and phototransistor receivers. When the gel displaced in the pipette crosses the sensing region of the photomicrosensors, it generates a signal collected on a computer through a dedicated acquisition board. The performance of the device was tested during the 2002 International Accident Dosimetry Intercomparison in Valduc, France. The dosemeter was able to follow the initial dose gradient of a simulated accident, providing accurate values of neutron kerma; however, the emulsion was rapidly depleted of all its drops. A model of the depletion effects was developed and it indicates that an adequate dynamic range of the dose response can be achieved by using emulsions of smaller droplets.

A neutron dosemeter for nuclear criticality accidents

International Nuclear Information System (INIS)

D'Errico, F.; Curzio, G.; Ciolini, R.; Del Gratta, A.; Nath, R.

2004-01-01

A neutron dosemeter which offers instant read-out has been developed for nuclear criticality accidents. The system is based on gels containing emulsions of superheated dichlorodifluoromethane droplets, which vaporise into bubbles upon neutron irradiation. The expansion of these bubbles displaces an equivalent volume of gel into a graduated pipette, providing an immediate measure of the dose. Instant read-out is achieved using an array of transmissive optical sensors which consist of coupled LED emitters and phototransistor receivers. When the gel displaced in the pipette crosses the sensing region of the photo microsensors, it generates a signal collected on a computer through a dedicated acquisition board. The performance of the device was tested during the 2002 International Accident Dosimetry Intercomparison in Valduc (France)). The dosemeter was able to follow the initial dose gradient of a simulated accident, providing accurate values of neutron kerma; however, the emulsion was rapidly depleted of all its drops. A model of the depletion effects was developed and it indicates that an adequate dynamic range of the dose response can be achieved by using emulsions of smaller droplets. (authors)

Simple estimate of fission rate during JCO criticality accident

Energy Technology Data Exchange (ETDEWEB)

Oyamatsu, Kazuhiro [Faculty of Studies on Contemporary Society, Aichi Shukutoku Univ., Nagakute, Aichi (Japan)

2000-03-01

The fission rate during JCO criticality accident is estimated from fission-product (FP) radioactivities in a uranium solution sample taken from the preparation basin 20 days after the accident. The FP radioactivity data are taken from a report by JAERI released in the Accident Investigation Committee. The total fission number is found quite dependent on the FP radioactivities and estimated to be about 4x10{sup 16} per liter, or 2x10{sup 18} per 16 kgU (assuming uranium concentration 278.9 g/liter). On the contrary, the time dependence of the fission rate is rather insensitive to the FP radioactivities. Hence, it is difficult to determine the fission number in the initial burst from the radioactivity data. (author)

Simple estimate of fission rate during JCO criticality accident

International Nuclear Information System (INIS)

Oyamatsu, Kazuhiro

2000-01-01

The fission rate during JCO criticality accident is estimated from fission-product (FP) radioactivities in a uranium solution sample taken from the preparation basin 20 days after the accident. The FP radioactivity data are taken from a report by JAERI released in the Accident Investigation Committee. The total fission number is found quite dependent on the FP radioactivities and estimated to be about 4x10 16 per liter, or 2x10 18 per 16 kgU (assuming uranium concentration 278.9 g/liter). On the contrary, the time dependence of the fission rate is rather insensitive to the FP radioactivities. Hence, it is difficult to determine the fission number in the initial burst from the radioactivity data. (author)

Criticality accidents in solution (CRAC and SILENE programmes) and complementary studies of accidents; radiation dosimetry in human organism during the CRAC programme

International Nuclear Information System (INIS)

Barbry, M.; Dousset, M.

C.R.A.C. (CRiticality occurring ACcidentally) programme is intended to study experimentally the development of a criticality accident as it could occur when handling solutions of fissile material as well as the radiological consequences of such an accident. The fissile matter solutions have been chosen (a) for practical considerations of use and (b) because the probability of an accident occurring seems greater with this type of environment, as the known accidents have shown. The programme is twofold: study of accident physics: form of the evolution (peak, plateau, oscillations, boil up of solutions) the most probable maximum power, minimal power, flux and radiation spectra emitted, freed energy, associated effects, radiolysis, constraints, etc., study of radiological consequences: area dosimetry, individual dosimetry, radiobiological studies, etc. Additional criticality Accident experiments have been and continue to be made on the SILENE reactor in the following principal domains: determination of the emission rate of gaseous fission products and aerosols, area dosimetry and health dosimetry in the presence of shields around the core to vary the neutron and gamma components of the radiation field. Improvement in the knowledge of certain particular aspects of the power excursion, radiolysis gas and pressure wave, experiments of the ''boiling'' type [fr

Fuel solution criticality accident studies with the SILENE reactor: phenomenology, consequences and simulated intervention

International Nuclear Information System (INIS)

Barbry, F.

1984-01-01

After defining the content and the objectives of criticality accident studies, the SILENE reactor, a means of studying fuel solution criticality accidents, is presented. Information obtained from the CRAC and SILENE experimental programs are then presented; they concern power excursion phenomenology, radiological consequences, and finally guide-lines for current and future programs

Evaluation of the 17 June 1997 Criticality Accident at Arzamas-16

International Nuclear Information System (INIS)

Morris Klein

1999-01-01

On June 17, 1997, a critically accident occurred at Arzamas-16, which resulted in the death (within three days) of A. N. Zakharov, a Russian scientist with 20 years' experience conducting multiassembly experiments. In this case, the multiplying assembly was a fast metal system consisting of a 235 U (90% enriched) core and a copper reflector. According to the Russian press, ''Zakharov misjudged the degree of criticality of the breeding system and committed several gross violations of regulations.'' As we see it, there were three major causes of this accident. First, the experiment was flawed by Zakharov's misreading of the appropriate size of the assembly, which he took from a notebook that described the old experiment he was attempting to repeat. Second, he disregarded the appropriate procedures and safety regulations. Third, these two mistakes were compounded by an improperly set audible alarm system and Zakharov's unsafe use of the table. We also discuss our reconstruction of the accident based on information given by the Russians to US scientists and information culled from Russian newspaper and magazine articles. We also describe our thoughts on the behavior of the assembly following the accident and the radiation dose level Zakharov may have received. These levels match values we have lately obtained from translations of Russian news articles. This accident clearly points out the penalty for weak administrative control of work with multiplying systems. Criticality experimentation requires formality of operation. The experimenter, his peers, and a trained safety person need to document that they understand the experiment and how it will be conducted. Knowing that the experiment was successfully run several decades ago does not justify bypassing a safety evaluation

Crisis, criticism, change: Regulatory reform in the wake of nuclear accidents

International Nuclear Information System (INIS)

Sexton, Kimberly A.; )

2015-01-01

Accidents are a forcing function for change in the nuclear industry. While these events can shed light on needed technical safety reforms, they can also shine a light on needed regulatory system reforms. The TEPCO Fukushima Daiichi nuclear power plant (NPP) accident in Japan is the most recent example of this phenomenon, but it is not the only one. In the wake of the three major accidents that have occurred in the nuclear power industry - Three Mile Island (TMI) in the United States; Chernobyl in Ukraine, in the former Soviet Union; and the Fukushima Daiichi NPP accident in Japan - a commission or committee of experts issued a report (or reports) with harsh criticism of the countries' regulatory system. And each of these accidents prompted changes in the respective regulatory systems. In looking at these responses, however, one must ask if this crisis, criticism, change approach is working and whether regulatory bodies around the world should instead undertake their own systematic reviews, un-prompted by crisis, to better ensure safety. This article will attempt to analyse the issue of regulatory reform in the wake of nuclear accidents by first providing a background in nuclear regulatory systems, looking to international and national legal frameworks. Next, the article will detail a cross-section of current regulatory systems around the world. Following that, the article will analyse the before and after of the regulatory systems in the United States, the Soviet Union and Japan in relation to the TMI, Chernobyl and Fukushima accidents. Finally, taking all this together, the article will address some of the international and national efforts to define exactly what makes a good regulator and provide conclusions on regulatory reform in the wake of nuclear accidents. (author)

Calculation code used in criticality analyses for the accident of JCO precipitation tank

International Nuclear Information System (INIS)

Miyoshi, Yoshinori

2000-01-01

In order to evaluate nuclear features on criticality accident formed at the nuclear fuel processing facility in Tokai Works of the JCO, Ltd. (JCO), in Tokai-mura, Ibaraki prefecture, dynamic analyses to calculate output change after occurring the accident as well as criticality analyses to calculate reactivity added to precipitation tank, were carried out according to scenario on accident formation. For the criticality analyses, a continuous energy Monte Carlo code MCNP was used to carry out calculation of reactivity fed into the precipitation tank as correctly as possible. And, SRAC code system was used for calculation on temperature and void reactivity coefficients, effective delayed neutron ratio beta eff , and instantaneous neutron generation time required for parameters controlling transition features at criticality accident. In addition, for the dynamic analyses, because of necessity of considering on volume expansion of solution fuels used as exothermic body and radiation decomposition gas forming into solution, output behavior, numbers of nuclear fission, and so forth at initial burst portion were calculated by using TRACE and quasi-regular code, at a center of AGNES-2 promoting on its development in JAERI. Here were reported on outlines and an analysis example on calculation code using for the nuclear features evaluation. (G.K.)

Neutron personal dosimetry in criticality accidents

International Nuclear Information System (INIS)

Fonseca, E.S. da; Mauricio, C.L.P.

1996-01-01

In the present work an innovating method is proposed to estimate the absorbed dose received by individuals irradiated with neutrons in an accident, even in the case that the victim is not using any kind of neutron dosemeter. The method combines direct measurements of 24 Na and 32 P activated in the human body. The calculation method was developed using data taken from previously published papers and experimental measurements. Other irradiations results in different neutron spectra prove the validity of the method here proposed. Using a whole body counter to measure 24 Na activity, it is possible to evaluate neutron absorbed doses in the order of 140 μ Gy of very soft (thermal) spectra. For fast neutron fields, the lower limit for neutron dose detection increases, but the present method continues to be very useful in accidents, with higher neutron doses. (author)

Recalibration of indium foil for personnel screening in criticality accidents.

Science.gov (United States)

Takada, C; Tsujimura, N; Mikami, S

2011-03-01

At the Nuclear Fuel Cycle Engineering Laboratories of the Japan Atomic Energy Agency (JAEA), small pieces of indium foil incorporated into personal dosemeters have been used for personnel screening in criticality accidents. Irradiation tests of the badges were performed using the SILENE reactor to verify the calibration of the indium activation that had been made in the 1980s and to recalibrate them for simulated criticalities that would be the most likely to occur in the solution process line. In addition, Monte Carlo calculations of the indium activation using the badge model were also made to complement the spectral dependence. The results lead to a screening level of 15 kcpm being determined that corresponds to a total dose of 0.25 Gy, which is also applicable in posterior-anterior exposure. The recalibration based on the latest study will provide a sounder basis for the screening procedure in the event of a criticality accident.

Initial medical management of criticality accident victim; Conduite a tenir aux victimes d'un accident de criticite

Energy Technology Data Exchange (ETDEWEB)

Miele, A; Bebaron-Jacobs, L

2005-07-01

The extremely severe criticality accidents known to this day, and the subsequent deaths recorded (Sarov 1997 and Tokai Mura 1999), demonstrate the need for sustained surveillance and constant adapted training for the teams in charge of irradiated and/or contaminated victims. The aim of this work group, composed of occupational health services and associated medical biology laboratories, is to present, in leaflet format, the essential data on the documentation and the conduct to be held when facing the victims of a criticality accident. The studies of this work group confirm the difficulties involved in managing this type of accident, both from the dosimetric evaluation point of view and from the therapeutic management point of view. That is why several research themes and perspectives are developed. During the different phases of victim triage, the recommendations given on these leaflets describe the operational conducts to be held. This work will have to be updated according to the evolution in knowledge and means: short and long term effects of exposure to neutrons, multi-competence hospital cooperation, expertise networks related to dosimetric reconstitution. (authors)

Instructions on the nuclear critical accident and how to correspond to future

International Nuclear Information System (INIS)

Kimura, Itsuro

2000-01-01

The nuclear accident occurred at Tokai Works of the JCO Co., Ltd. is a simple but disallowable one formed by neglecting possibility of nuclear fission chain reaction, one of three dangers specific to nuclear power facilities and by feeding middle concentrated uranium solution with more than critical mass into a precipitation tank. As a man consumed most of his life to nuclear power, it is to occur a critical accident forming about 50 previous examples in the world and about 10 victims at Tokai-mura the most earnestly promoting its experiment and analysis and to generate new victims, what was thought to be the most regrettable in this accident. How the previous experiences and results in Tokai-mura could be transmitted to the JCO Co., Ltd. ? This was a large alarm-bell for persons engaging to R and D on nuclear power. As this accident was much deplorable and apological for the common public, it must be carried out to thoroughly analyze its causes, to establish its future responses, and to promote its essential countermeasures. As it is important to open informations on its contents, it is hopeful not to over-exaggerate and over-differentiate the accident, to calmly and scientifically analyze the risk as well as in the other accidents, and to construct actually effective countermeasures. (G.K.)

Triage and medical management of criticality accident victims

International Nuclear Information System (INIS)

Lebaron-Jacobs, L.; Flury-Herard, A.; Cavadore, D.

2002-01-01

The criticality accident is the result of an uncontrolled chain fission reaction initiated when the quantities of nuclear materials (uranium or plutonium)present accidentally exceed a given limit called the c ritical mass . As soon as the critical state is exceeded, the chain reaction increases exponentially. The result is a fast increase in the number of fission events which occur within the fissile medium. This phenomenon results in a release of energy mainly in the form of heat, accompanied by the intense emission of neutron and gamma radiation and the release of fission gases (Barby, 1983)

Safety demonstration analyses on criticality for severe accident during overland transport of fresh nuclear fuel

International Nuclear Information System (INIS)

Takahashi, Satoshi; Okuno, Hiroshi; Yamada, Kenji; Watanabe, Kouji; Nomura, Yasushi; Miyoshi, Yoshinori

2005-01-01

Criticality safety analysis was performed for transport packages of uranium dioxide powder or of fresh PWR fuel involved in a severe accident during overland transportation, and as a result, sub-criticality was confirmed against impact accident conditions such as loaded by a drop from high position to a concrete or asphalt surface, and fire accident conditions such as caused by collisions with an oil tank trailer carrying lots of inflammable material in open air, or with a commonly used two-ton-truck inside an unventilated tunnel. (author)

The Tokai-mura JCO criticality accident and the activities of the accident countermeasure support team of Electric Power Companies, Japan

International Nuclear Information System (INIS)

Ogawa, Junko

2000-01-01

A criticality accident occurred at the JCO Tokai-mura nuclear fuel processing plant on September 30, 1999. This accident brought the damages which were unrivaled in the history of atomic energy development in Japan, seriously influencing the citizen life to such an extent as requesting for 320,000 inhabitants within 10 kilometers radius to stay indoors for as long as 18 hours. However, it could be said that though three workers suffered fatal injuries, no substantial hazards were made upon the regional inhabitants due to little release of radioactive substances. This video recorded the activities of the Accident Countermeasure Support Team of the Electric Power Companies immediately after the accident occurred, showing the chronological overview of the particulars of the accident. (author)

NIRS report of the criticality accident in a uranium conversion test plant in Tokai-mura

International Nuclear Information System (INIS)

2001-01-01

This report is a detailed account of the roles that National Institute of Radiological Sciences (NIRS) played at the criticality accident in the title, which occurred at around 10:35, on Sep. 30, 1999 and resulted in death of two workers after all, and is published to discharge NIRS responsibilities in regards to the accident. The accident caused many residents concern on their health and rumors had both social and economic consequences. The report involves chapters of detailed outline of the accident; demand for acceptance of the victims and communications until the identification of the criticality'' accident; the acceptance and initial treatment; the exposure dose estimation (based on acute symptoms, on physics, on chromosomal analyses and on neutron-activated dental metals, and detailed analyses for dose distribution); decision made for therapeutic strategies; cooperation with the Network Council for Radiation Emergency and with other medical facilities; the urgent import of medicine; treatment and processes (patients, nursing system and radiation injuries); radiation protection in medical facilities; response to nearby residents of the Plant; international response; press release; Uranium Processing Plant Criticality Accident Investigation Committee and the Health Management Committee organized by the Nuclear Safety Commission; handling of information; and radiation emergency medical preparedness at the NIRS (future issues and prospect). The report is hopefully useful in preventing the occurrence of future accidents. (N.I.)

Initial medical management of criticality accident victim; Conduite a tenir aux victimes d'un accident de criticite

Energy Technology Data Exchange (ETDEWEB)

Miele, A.; Bebaron-Jacobs, L

2005-07-01

The extremely severe criticality accidents known to this day, and the subsequent deaths recorded (Sarov 1997 and Tokai Mura 1999), demonstrate the need for sustained surveillance and constant adapted training for the teams in charge of irradiated and/or contaminated victims. The aim of this work group, composed of occupational health services and associated medical biology laboratories, is to present, in leaflet format, the essential data on the documentation and the conduct to be held when facing the victims of a criticality accident. The studies of this work group confirm the difficulties involved in managing this type of accident, both from the dosimetric evaluation point of view and from the therapeutic management point of view. That is why several research themes and perspectives are developed. During the different phases of victim triage, the recommendations given on these leaflets describe the operational conducts to be held. This work will have to be updated according to the evolution in knowledge and means: short and long term effects of exposure to neutrons, multi-competence hospital cooperation, expertise networks related to dosimetric reconstitution. (authors)

Unrecorded Accidents Detection on Highways Based on Temporal Data Mining

Directory of Open Access Journals (Sweden)

Shi An

2014-01-01

Full Text Available Automatic traffic accident detection, especially not recorded by traffic police, is crucial to accident black spots identification and traffic safety. A new method of detecting traffic accidents is proposed based on temporal data mining, which can identify the unknown and unrecorded accidents by traffic police. Time series model was constructed using ternary numbers to reflect the state of traffic flow based on cell transmission model. In order to deal with the aftereffects of linear drift between time series and to reduce the computational cost, discrete Fourier transform was implemented to turn time series from time domain to frequency domain. The pattern of the time series when an accident happened could be recognized using the historical crash data. Then taking Euclidean distance as the similarity evaluation function, similarity data mining of the transformed time series was carried out. If the result was less than the given threshold, the two time series were similar and an accident happened probably. A numerical example was carried out and the results verified the effectiveness of the proposed method.

CARNAC, Neutron Flux and Neutron Spectra in Criticality Accident

International Nuclear Information System (INIS)

Bessis, J.

1976-01-01

Nature of physical problem solved: Calculation of flux and neutron spectra in the case of a criticality accident. The method is unsophisticated but fast. The program is divided into two parts: (1) The code CRITIC is based on the Fermi age equation and evaluates the neutron number per fission emitted from a moderate critical system and its energy spectrum. (2) The code NARCISSE uses concrete current albedo, evaluates the product of neutron reflection on walls of the source containment and calculates the resulting flux at any point, and its energy distribution into 21 groups. The results obtained seem satisfactory, if compared with a Monte Carlo program

Nuclear criticality safety: general. 3. Tokaimura Criticality Accident: Point Model Stochastic Neutronic Interpretation

International Nuclear Information System (INIS)

Mechitoua, Boukhmes

2001-01-01

This paper shows what can be the stochastic neutronic contribution for the interpretation of criticality accidents. Stochastic neutronic comprehensive texts may be found in refs.1 through 4. We limit our study to the use of initiation probability, which is an important stochastic neutronic tally. Initiation probability P may be defined as the probability for one neutron to initiate an infinite neutron fission chain. The complement probability of P is the extinction probability Q. The probability that the neutron fission chain produced by one neutron will quench is equal to the multiplication of the probability of production of i neutrons g i by the probability of extinction of these i neutrons. We can estimate P by a Newton or by a dichotomic method. We suppose that P S (t) is the probability that an infinite neutron fission chain has been initiated before time t by a neutron produced by the source S(t). P S (t + dt) is the sum of two probabilities: 1. the probability that an infinite neutron fission chain has been initiated before time t by a neutron produced by the source S(t): P S (t); 2. The second probability is a multiplication of two probabilities: the probability that there was no initiation before t that is 1-P S (t), and the probability that a neutron emitted by the source with the probability S dt initiates an infinite neutron fission chain with the probability P(t). This last relation gives the link between P and the source density. The aim of this paper is to show how one can apply the foregoing derivations. We have simplified the Tokaimura criticality accident for this application. We have mono-energetic neutrons with infinite and homogeneous media; we have two reactions: capture and fission. In this section, we show how one can estimate the initiation probability with a source density as a function of time. This estimation makes use of three steps: 1. Reactivity insertion: Estimation of the multiplication coefficient as a function of time K(t). This

The report of the criticality accident in a uranium conversion test plant in Tokai-mura

International Nuclear Information System (INIS)

Murata, Hajime; Akashi, Makoto

2002-03-01

The criticality accident in the title occurred at around 10:35, on Sep. 30, 1999, cost the lives of two workers and caused many residents concern on their health. Moreover, rumors had both social and economic consequences. This report is a detailed account of the roles that many individuals and groups in the National Institute of Radiological Sciences (NIRS) performed in a range of the areas, and is published to discharge NIRS responsibilities in regards to the accident. The report involves chapters of detailed outline of the accident; acceptance of the victims and communications until the identification of the ''criticality'' accident; initial treatment; dose estimation (medical, hematological, physical and biological ones and that by dental metals activated by the neutron); decision making for therapeutic strategies; cooperation with the Network Council for Radiation Emergency Medicine and other medical facilities; emergency importation of medical supplies; treatment and progress (nursing system and radiation injuries); protection from radiation in medical facilities; response to nearby residents of the Plant; international response; press release; Uranium Processing Plant Criticality Accident Investigation Committee and the Health Management Committee organized by the Nuclear Safety Commission; handling of information; and radiation emergency medical preparedness at the NIRS (future issues and prospect). The report is hoped to be useful in preventing the occurrence of future accidents. (K.H.)

Radiation monitoring using imaging plate technology: A case study of leaves affected by the Chernobyl nuclear power plant and JCO criticality accidents

Directory of Open Access Journals (Sweden)

Kimura Shinzo

2006-01-01

Full Text Available This paper describes the use of a photostimulable phosphor screen imaging technique to detect radioactive contamination in the leaves of wormwood (Artemisia vulgaris L and fern (Dryopteris filix-max CL. Schoff plants affected by the Chernobyl nuclear power plant accident. The imaging plate technology is well known for many striking performances in two-dimensional radiation detection. Since imaging plate comprises an integrated detection system, it has been extensively applied to surface contamination distribution studies. In this study, plant samples were collected from high- and low-contaminated areas of Ukraine and Belarus, which were affected due to the Chernobyl accident and exposed to imaging technique. Samples from the highly contaminated areas revealed the highest photo-stimulated luminescence on the imaging plate. Moreover, the radio nuclides detected in the leaves by gamma and beta ray spectroscopy were 137Cs and 90Sr, respectively. Additionally, in order to assess contamination, a comparison was also made with leaves of plants affected during the JCO criticality accident in Japan. Based on the results obtained, the importance of imaging plate technology in environmental radiation monitoring has been suggested.

Activities of JAERI's health physics department for the criticality accident of JCO

International Nuclear Information System (INIS)

Yamamoto, Katsumune; Kitano, Kyoshiro; Murakami, Hiroyuki; Yamaguchi, Takenori; Tsunoda, Masahiko

2000-01-01

This report describes early health physics activities from September 30 to October 1 taken by the authors' department after the JCO accident. They firstly knew the accident at around 12:20 (about 2 hr after the criticality). The activities involved the planning of schedule for ending the criticality; calculation of scheduled dose for the work to end it; dose measurement around JCO site; loaning out of devices for measuring neutron and of personal dose-meter; collection and radioactivity measurement of dust and soil, and of drinking water; and examination for contamination of people around the site, of their houses inside and of school gardens and equipments. The dose was scheduled to be firstly 20 mSv and then changed to 50 mSv due to the actual measurement at the accident site. The working time was to be 3 min at the site. The work was on either the dose or time. Radiation monitoring outside the JCO site revealed the presence of Na-24 and Cs-138: neutron dose was 10 times as high as γ-ray dose. The time course of dose rate change was found to be in parallel with the progress of works to end the criticality. (K.H.)

Determination of the response function for the Portsmouth Gaseous Diffusion Plant criticality accident alarm system neutron detectors

International Nuclear Information System (INIS)

Tayloe, R.W. Jr.; Brown, A.S.; Dobelbower, M.C.; Woollard, J.E.

1997-03-01

Neutron-sensitive radiation detectors are used in the Portsmouth Gaseous Diffusion Plant's (PORTS) criticality accident alarm system (CAAS). The CAAS is composed of numerous detectors, electronics, and logic units. It uses a telemetry system to sound building evacuation horns and to provide remote alarm status in a central control facility. The ANSI Standard for a CAAS uses a free-in-air dose rate to define the detection criteria for a minimum accident-of-concern. Previously, the free-in-air absorbed dose rate from neutrons was used for determining the areal coverge of criticality detection within PORTS buildings handling fissile materials. However, the free-in-air dose rate does not accurately reflect the response of the neutron detectors in use at PORTS. Because the cost of placing additional CAAS detectors in areas of questionable coverage (based on a free-in-air absorbed dose rate) is high, the actual response function for the CAAS neutron detectors was determined. This report, which is organized into three major sections, discusses how the actual response function for the PORTS CAAS neutron detectors was determined. The CAAS neutron detectors are described in Section 2. The model of the detector system developed to facilitate calculation of the response function is discussed in Section 3. The results of the calculations, including confirmatory measurements with neutron sources, are given in Section 4

Radiological dose assessment for bounding accident scenarios at the Critical Experiment Facility, TA-18, Los Alamos National Laboratory

International Nuclear Information System (INIS)

1991-09-01

A computer modeling code, CRIT8, was written to allow prediction of the radiological doses to workers and members of the public resulting from these postulated maximum-effect accidents. The code accounts for the relationships of the initial parent radionuclide inventory at the time of the accident to the growth of radioactive daughter products, and considers the atmospheric conditions at time of release. The code then calculates a dose at chosen receptor locations for the sum of radionuclides produced as a result of the accident. Both criticality and non-criticality accidents are examined

Chemical dosimetry system for criticality accidents.

Science.gov (United States)

Miljanić, Saveta; Ilijas, Boris

2004-01-01

Ruder Bosković Institute (RBI) criticality dosimetry system consists of a chemical dosimetry system for measuring the total (neutron + gamma) dose, and a thermoluminescent (TL) dosimetry system for a separate determination of the gamma ray component. The use of the chemical dosemeter solution chlorobenzene-ethanol-trimethylpentane (CET) is based on the radiolytic formation of hydrochloric acid, which protonates a pH indicator, thymolsulphonphthalein. The high molar absorptivity of its red form at 552 nm is responsible for a high sensitivity of the system: doses in the range 0.2-15 Gy can be measured. The dosemeter has been designed as a glass ampoule filled with the CET solution and inserted into a pen-shaped plastic holder. For dose determinations, a newly constructed optoelectronic reader has been used. The RBI team took part in the International Intercomparison of Criticality Accident Dosimetry Systems at the SILENE Reactor, Valduc, June 2002, with the CET dosimetry system. For gamma ray dose determination TLD-700 TL detectors were used. The results obtained with CET dosemeter show very good agreement with the reference values.

An analysis on human factor issues in criticality accident at a uranium processing plant

International Nuclear Information System (INIS)

Sasou, Kunihide; Goda, Hidenori; Hirotsu, Yuko

2000-01-01

This report analyses latent factors of a human behavior directly contributing to the criticality accident. It is pouring some 16 kg-U with an enrichment of 18.8% into the precipitation tank. It is the fact that the direct cause of this accident is the workers' unsafe act. However, the authors find lots of latent factors relating to the production-biased company's policy, the poor climate for safety in the work place, the inadequate safety management and the unsuitable equipment. This accident was caused by many organizational factors. This paper also discusses lessons learned from this accident. (author)

The relationship of JNC and JCO in the uranium processing plant criticality accident

International Nuclear Information System (INIS)

Kanamori, Masashi; Yanagibashi, Katsumi; Okamoto, Naritoshi

2002-12-01

On September 30th 1999, the criticality accident occurred at JCO's uranium conversion building in Tokai. The accident occurred during reconversion from U 3 O 8 to uranium nitrate solution (UNH) with uranium enriched 18.8% and about 60 kgU. JCO contacted with JNC to supply UNH that is fuel material for the experimental fast breeder reactor 'JOYO'. JNC has contracted with JCO that had started nuclear fuel material processing business following a definite policy of Japanese government and developed SUMITOMO ADU PROCESS'. JNC made the first contract with JCO in 1985 and has made a contact every year. There had never been a problem in their products. JNC inspected products based on contract. JNC discharge our duty as customer inspecting products based on contract. As for safety control, JCO had taken licensing safety review and had been permitted to be 'a processing facility'. Therefore JNC understood that JCO produced following this license. 'The Uranium Processing Plant Criticality Accident Investigation' showed that JCO had been taking a different method from the permit and violating the license. However JNC had never been explained about that and JCO's operation procedures had never described about that. Therefore the Criticality Accident couldn't be avoided. This report describes the relationship of JNC and JCO in the uranium reconversion contract for JOYO, atomic development policy of Japanese government, process to the order and the contents of contract. (author)

Organizational factors and reoccurrence protection on the JCO nuclear critical accident

International Nuclear Information System (INIS)

Takano, Kenichi

2000-01-01

A nuclear critical accident formed at a nuclear fuel conversion factory in Tokai-mura on September, 1999 became gradually clear not to be a simple human error formed at a level of workmen but to be an organizational error or accident relating to various organizational factors. As a nuclear power facility adopts a depth protection system fundamentally, a large accident with serious danger would not form only by a single trouble and a human error and unless some factors overlaps. By reviewing recent serious accidents and troubles, all of them seem to have a keyword of 'organizational factor'. In the JCO accident, there are some organizational factors such as a climate deviating from a manual, insufficient and loose check against change of procedure, reduction of operators from a reason of profit priority, attitude on priority of working efficiency, and so forth, which are partially common to the Chernobyl accident. Recently, accidents and troubles impossible to make them a cause of simple human error by a person but to have to say an organizational error, have increased. This trend seems to depend upon not only complication and scale-up of technology system but also graduate change of social and management systems operating them. Therefore, it seems to be necessary to introduce a concept of depth protection (multiple protection) in order to keep its reliability and safety when complicating and scaling-up of system. (G.K.)

A microcomputer-based model for identifying urban and suburban roadways with critical large truck accident rates

International Nuclear Information System (INIS)

Brogan, J.D.; Cashwell, J.W.

1992-01-01

This paper presents an overview of techniques for merging highway accident record and roadway inventory files and employing the combined data set to identify spots or sections on highway facilities in urban and suburban areas with unusually high large truck accident rates. A statistical technique, the rate/quality control method, is used to calculate a critical rate for each location of interest. This critical rate may then be compared to the location's actual accident rate to identify locations for further study. Model enhancements and modifications are described to enable the technique to be employed in the evaluation of routing alternatives for the transport of radioactive material

Critical analysis of accident scenario and consequences modelling applied to light-water reactor power plants for accident categories beyond the design basis accident (DBA)

International Nuclear Information System (INIS)

Brofferio, C.; Cagnetti, P.; Ferrara, V.; Manilia, E.; Pietrangeli, G.; Sennis, C.

1985-01-01

A critical analysis and sensitivity study of the modelling of accident scenarios and environmental consequences are presented, for light-water reactor accident categories beyond the standard design-basis-accident category. The first chapter, on ''source term'' deals with the release of fission products from a damaged core inventory and their migration within the primary circuit and the reactor containment. Particular attention is given to the influence of engineering safeguards intervention and of the chemical forms of the released fission products. The second chapter deals with their release to the atmosphere, transport and wet or dry deposition, outlining relevant partial effects and confronting short-duration or prolonged releases. The third chapter presents a variability analysis, for environmental contamination levels, for two extreme hypothetical scenarios, evidencing the importance of plume rise. A numerical plume rise model is outlined

Participation of IRD/CNEN-Br in International Intercomparison of Criticality Accident Dosimetry Systems at Silene reactor, France

International Nuclear Information System (INIS)

Mauricio, Claudia Lucia P.; Fonseca, Evaldo S. da

1996-01-01

IRD has participated in an International Intercomparison of Criticality Accident Dosimetry Systems at the SILENE reactor, France on June 1993. The dosemeters were irradiated on phantoms and free in air, in bare and lead shield reactor pulses, simulating different irradiation fields that can be found in criticality accidents. Comparing with the reference measurements, the calculated mean neutron kerma found by IRD was only 2% greater for lead shield and 14% greater for bare reactor. For gamma absorbed dose, the differences were, respectively + 22% and -9% for the dosemeters free in air and -19% and -9% for dosemeters on phantoms. IRD results are closer to the real values than the mean values measured by the participants. IRD results show a good performance if its simple criticality accident system. (author)

A critical assessment of energy accident studies

International Nuclear Information System (INIS)

Felder, Frank A.

2009-01-01

A comparison of two studies conducted ten years apart on energy accidents provides important insights into methodological issues and policy implications. Recommendations for further improvements in energy accident studies are developed including accounting for differences between average and incremental accident damages, testing for appropriate levels of aggregation of accidents, making references and databases publicly available, more precisely defining and reporting different types of economic damages, accounting for involuntary and voluntary risks, reporting normalized damages, raising broader public policy and planning implications and updating existing accident databases.

A critical assessment of energy accident studies

Energy Technology Data Exchange (ETDEWEB)

Felder, Frank A. [Edward J. Bloustein School of Planning and Public Policy, Rutgers, The State University of New Jersey, 33 Livingston Avenue, New Brunswick, NJ 08901 (United States)

2009-12-15

A comparison of two studies conducted ten years apart on energy accidents provides important insights into methodological issues and policy implications. Recommendations for further improvements in energy accident studies are developed including accounting for differences between average and incremental accident damages, testing for appropriate levels of aggregation of accidents, making references and databases publicly available, more precisely defining and reporting different types of economic damages, accounting for involuntary and voluntary risks, reporting normalized damages, raising broader public policy and planning implications and updating existing accident databases. (author)

Update of the Nuclear Criticality Slide Rule for the Emergency Response to a Nuclear Criticality Accident

Science.gov (United States)

Duluc, Matthieu; Bardelay, Aurélie; Celik, Cihangir; Heinrichs, Dave; Hopper, Calvin; Jones, Richard; Kim, Soon; Miller, Thomas; Troisne, Marc; Wilson, Chris

2017-09-01

AWE (UK), IRSN (France), LLNL (USA) and ORNL (USA) began a long term collaboration effort in 2015 to update the nuclear criticality Slide Rule for the emergency response to a nuclear criticality accident. This document, published almost 20 years ago, gives order of magnitude estimates of key parameters, such as number of fissions and doses (neutron and gamma), useful for emergency response teams and public authorities. This paper will present, firstly the motivation and the long term objectives for this update, then the overview of the initial configurations for updated calculations and preliminary results obtained with modern 3D codes.

Update of the Nuclear Criticality Slide Rule for the Emergency Response to a Nuclear Criticality Accident

Directory of Open Access Journals (Sweden)

Duluc Matthieu

2017-01-01

Full Text Available AWE (UK, IRSN (France, LLNL (USA and ORNL (USA began a long term collaboration effort in 2015 to update the nuclear criticality Slide Rule for the emergency response to a nuclear criticality accident. This document, published almost 20 years ago, gives order of magnitude estimates of key parameters, such as number of fissions and doses (neutron and gamma, useful for emergency response teams and public authorities. This paper will present, firstly the motivation and the long term objectives for this update, then the overview of the initial configurations for updated calculations and preliminary results obtained with modern 3D codes.

Nuclear accident dosimetry

International Nuclear Information System (INIS)

1982-01-01

The film presents statistical data on criticality accidents. It outlines past IAEA activities on criticality accident dosimetry and the technical documents that resulted from this work. The film furthermore illustrates an international comparison study on nuclear accident dosimetry conducted at the Atomic Energy Research Establishment, Harwell, United Kingdom

Nuclear accident dosimetry

Energy Technology Data Exchange (ETDEWEB)

NONE

1983-12-31

The film presents statistical data on criticality accidents. It outlines past IAEA activities on criticality accident dosimetry and the technical documents that resulted from this work. The film furthermore illustrates an international comparison study on nuclear accident dosimetry conducted at the Atomic Energy Research Establishment, Harwell, United Kingdom

Questionnaire survey report about the criticality accident at a nuclear fuel processing facility

International Nuclear Information System (INIS)

2000-01-01

The Radiation Protection Section of the Japanese Society of Radiological Technology conducted a questionnaire survey on the criticality accident at the nuclear fuel processing facility in Tokai village on September 30, 1999 in order to identify factors related to the accident and consider countermeasures to deal with such accidents. The questionnaire was distributed to 347 members (122 facilities) of the Japanese Society of Radiological Technology who were working or living in Ibaraki Prefecture, and replies were obtained from 104 members (75 facilities). Questions to elicit the opinions of individuals were as following: method of obtaining information about the accident, knowledge about radiation, opinions about the accident, and requests directed to the Society. Questions regarding facilities concerned the following: communication after the accident, requests for dispatch to the accident site, and possession of radiometry devices. In regard to acquisition of information, 91 of the 104 members (87.5%) answered 'television or radios' followed by newspapers. Forty-five of 101 members were questioned about radiation exposure and radiation effects by the public. There were many opinions that accurate news should be provided rapidly, by the mass media. Many members (75%) felt that they lacked knowledge about radiation, reconfirming the importance of education and instruction concerning radiation. Dispatch was requested of 36 of the 75 facilities (48%), and 44 of 83 facilities (53%) owned radiometry instruments. (K.H.)

Criticality accident in uranium fuel processing plant. Questionnaires from Research Committee of Nuclear Safety

International Nuclear Information System (INIS)

Kataoka, Isao; Sekimoto, Hiroshi

2000-01-01

The Research Committee of Nuclear Safety carried out a research on criticality accident at the JCO plant according to statement of president of the Japan Atomic Energy Society on October 8, 1999, of which results are planned to be summarized by the constitutions shown as follows, for a report on the 'Questionnaires of criticality accident in the Uranium Fuel Processing Plant of the JCO, Inc.': general criticality safety, fuel cycle and the JCO, Inc.; elucidation on progress and fact of accident; cause analysis and problem picking-up; proposals on improvement; and duty of the Society. Among them, on last two items, because of a conclusion to be required for members of the Society at discussions of the Committee, some questionnaires were send to more than 1800 of them on April 5, 2000 with name of chairman of the Committee. As results of the questionnaires contained proposals and opinions on a great numbers of fields, some key-words like words were found on a shape of repeating in most questionnaires. As they were thought to be very important nuclei in these two items, they were further largely classified to use for summarizing proposals and opinions on the questionnaires. This questionnaire had a big characteristic on the duty of the Society in comparison with those in the other organizations. (G.K.)

Multiple parameter biodosimetry of exposed workers from the JCO criticality accident in Tokai-mura

Energy Technology Data Exchange (ETDEWEB)

Blakely, William F. [Armed Forces Radiobiology Research Institute, Bethesda, MD (United States)

2002-03-01

molecular biomarkers for neutron exposures in order to overcome this limitation. Lymphocyte counts were used to estimate radiation doses for the same three severely exposed patients. Haematological responses are an early response biomarker for radiation dose assessment. Goans and colleagues earlier reported lymphocyte depletion kinetic models for dose estimates based on human radiation accident registry data for whole-body acute gamma exposures and more recently for criticality accidents. Their data indicate a neutron RBE for lymphocyte depletion kinetics close to unity. Measurement of lymphocyte depletion kinetics is useful for initial dose estimation for radiation accidents. This biodosimetric approach alone, however, does not gauge the greater effectiveness of neutron radiation in criticality accidents involving mixed neutron and gamma radiation. Sodium-24 counts, with both blood and whole-body (Worker C) counts based on neutron activation of stable {sup 23}Na, were also used to obtain early estimates of absorbed doses for the Tokai-mura victims. The measurement of {sup 32}P in blood and urine samples is a potentially useful alternative for estimation of severe neutron radiation exposures because, during interaction with biological materials, fast neutrons convert {sup 32}S to {sup 32}P and thermal neutrons convert {sup 31}P to {sup 32}P. Nishimura and colleagues report, in the accompanying article in this issue, blood and urine {sup 32}P values obtained from the three severely exposed patients in the JCO criticality accident. These data, combined with dose estimates derived from other approaches, can contribute to the establishment of an in vivo human calibration curve for neutron dose assessment based on urine {sup 32}P kinetics measurements. The current state of the art for dose assessment following radiation accidents involves use of multiple parameter biological dosimetry. Several of the radiation bioassays (i.e., chromosome aberrations, lymphocyte counts, prodromal

Development of criticality accident detector measuring neutrons and gamma-rays

International Nuclear Information System (INIS)

Tsujimura, Norio; Yoshida, Tadayoshi; Ishii, Masato

2005-01-01

The authors developed a new criticality accident detector measuring neutrons and gamma-rays. The detector is a cylindrical plastic scintillator coupled to a current-mode operated photomultiplier, and is covered by an inner cadmium shell, acting as a neutron to gamma-ray converter, and a 5cm thick outer polyethylene moderator in order to respond to the same threshold triggering dose regardless of whether it was exposed to neutrons, gamma-rays or a mixture of the two radiations. (author)

PNNL Measurement Results for the 2016 Criticality Accident Dosimetry Exercise at the Nevada National Security Stite (IER-148)

Energy Technology Data Exchange (ETDEWEB)

Rathbone, Bruce A.; Morley, Shannon M.; Stephens, John A.

2017-05-01

The Pacific Northwest National Laboratory (PNNL) participated in a criticality accident dosimetry intercomparison exercise held at the Nevada National Security Site (NNSS) May 24-27, 2016. The exercise was administered by Lawrence Livermore National Laboratory (LLNL) and consisted of three exposures performed using the Godiva-IV critical assembly housed in the Device Assembly Facility (DAF) located on the NNSS site. The exercise allowed participants to test the ability of their nuclear accident dosimeters to meet the performance criteria in ANSI/HPS N13.3-2013, Dosimetry for Criticality Accidents and to obtain new measurement data for use in revising dose calculation methods and quick sort screening methods where appropriate. PNNL participated with new prototype Personal Nuclear Accident Dosimeter (PNAD) and Fixed Nuclear Accident Dosimeter (FNAD) designs as well as the existing historical PNAD design. The new prototype designs incorporate optically stimulated luminescence (OSL) dosimeters in place of thermoluminescence dosimeters (TLDs), among other design changes, while retaining the same set of activation foils historically used. The default dose calculation methodology established decades ago for use with activation foils in PNNL PNADs and FNADs was used to calculate neutron dose results for both the existing and prototype dosimeters tested in the exercise. The results indicate that the effective cross sections and/or dose conversion factors used historically need to be updated to accurately measure the operational quantities recommended for nuclear accident dosimetry in ANSI/HPS N13.3-2013 and to ensure PNAD and FNAD performance meets the ANSI/HPS N13.3-2013 performance criteria. The operational quantities recommended for nuclear accident dosimetry are personal absorbed dose, Dp(10), and ambient absorbed dose, D*(10).

Updated tool for nuclear criticality accident emergency response

International Nuclear Information System (INIS)

Broadhead, B.L.; Hopper, C.M.

1995-01-01

Some 20 yr ago a hand-held slide rule was developed at the Oak Ridge Y-12 Plant to aid in the response to several postulated nuclear criticality accidents. These assumed accidents involved highly enriched uranium in either a bare metal or a uranyl nitrate system. The slide rule consisted of a sliding scale based on the total fission yield and four corresponding dose indicators: (1) a prompt radiation dose relationship as a function of distance; (2) a delayed fission product gamma dose rate relationship as a function of time and distance; (3) the total dose relationship with time and distance; and (4) the I-min integrated dose relationship with time and distance. The original slide rule was generated assuming very simplistic numerical procedures such as the inverse-square relationship of dose with distance and the Way-Wigner relationship to express the time dependence of the dose. The simple prescriptions were tied to actual dose measurements from similar systems to yield a meaningful, yet simple approach to emergency planning and response needs. This paper describes the application of an advanced procedure to the updating of the original slide rule for five critical systems. These five systems include (a) an unreflected sphere of 93.2 wt% enriched uranium metal, (b) an unreflected sphere of 93.2 wt% enriched uranyl nitrate solution with a H/ 235 U ratio of 500, (c) an unreflected sphere of damp 93.2 wt% enriched uranium oxide with a H/ 235 U ratio of 10, (d) an unreflected sphere of 4.95 wt% enriched uranyl fluoride solution having a H/ 235 U ratio of 410, and (e) an unreflected sphere of damp 5 wt% enriched uranium dioxide having a H/ 235 U ratio of 200

The ENEA criticality accident dosimetry system: a contribution to the 2002 international intercomparison at the SILENE reactor.

Science.gov (United States)

Gualdrini, G; Bedogni, R; Fantuzzi, E; Mariotti, F

2004-01-01

The present paper summarises the activity carried out at the ENEA Radiation Protection Institute for updating the methodologies employed for the evaluation of the neutron and photon dose to the exposed workers in case of a criticality accident, in the framework of the 'International Intercomparison of Criticality Accident Dosimetry Systems' (Silène reactor, IRSN-CEA-Valduc June 2002). The evaluation of the neutron spectra and the neutron dosimetric quantities relies on activation detectors and on unfolding algorithms. Thermoluminescent detectors are employed for the gamma dose measurement. The work is aimed at accurately characterising the measurement system and, at the same time, testing the algorithms. Useful spectral information were included, based on Monte Carlo simulations, to take into account the potential accident scenarios of practical interest. All along this exercise intercomparison a particular attention was devoted to the 'traceability' of all the experimental and computational parameters and therefore, aimed at an easy treatment by the user.

Criticality accident in uranium fuel processing plant. The estimation of the total number of fissions with related reactor physics parameters

International Nuclear Information System (INIS)

Nishina, Kojiro; Oyamatsu, Kazuhiro; Kondo, Shunsuke; Sekimoto, Hiroshi; Ishitani, Kazuki; Yamane, Yoshihiro; Miyoshi, Yoshinori

2000-01-01

This accident occurred when workers were pouring a uranium solution into a precipitation tank with handy operation against the established procedure and both the cylindrical diameter and the total mass exceeded the limited values. As a result, nuclear fission chain reactor in the solution reached not only a 'criticality' state continuing it independently but also an instantly forming criticality state exceed the criticality and increasing further nuclear fission number. The place occurring the accident at this time was not reactor but a place having not to form 'criticality' called by a processing process of uranium fuel. In such place, as because of relating to mechanism of chain reaction, it is required naturally for knowledge on the reactor physics, it is also necessary to understand chemical reaction in chemical process, and functions of tanks, valves and pumps mounted at the processes. For this purpose, some information on uranium concentration ratio, atomic density of nuclides largely affecting to chain reaction such as uranium, hydrogen, and so forth in the solution, shape, inner structure and size of container for the solution, and its temperature and total volume, were necessary for determining criticality volume of the accident uranium solution by using nuclear physics procedures. Here were described on estimation of energy emission in the JCO accident, estimation from analytical results on neutron and solution, calculation of various nuclear physics property estimation on the JCO precipitation tank at JAERI. (G.K.)

Improved dose estimates for nuclear criticality accidents

International Nuclear Information System (INIS)

Wilkinson, A.D.; Basoglu, B.; Bentley, C.L.; Dunn, M.E.; Plaster, M.J.; Dodds, H.L.; Yamamoto, T.

1995-01-01

Slide rules are improved for estimating doses and dose rates resulting from nuclear criticality accidents. The original slide rules were created for highly enriched uranium solutions and metals using hand calculations along with the decades old Way-Wigner radioactive decay relationship and the inverse square law. This work uses state-of-the-art methods and better data to improve the original slide rules and also to extend the slide rule concept to three additional systems; i.e., highly enriched (93.2 wt%) uranium damp (H/ 235 U = 10) powder (U 3 O 8 ) and low-enriched (5 wt%) uranium mixtures (UO 2 F 2 ) with a H/ 235 U ratio of 200 and 500. Although the improved slide rules differ only slightly from the original slide rules, the improved slide rules and also the new slide rules can be used with greater confidence since they are based on more rigorous methods and better nuclear data

Design of and experience with the gamma-detecting criticality accident alarm system at ALKEM MOX fuel fabrication plant

International Nuclear Information System (INIS)

Kindleben, G.

1988-01-01

At ALKEM mixed oxide fuel fabrication plant there are two criticality accident alarm systems in operation and another one is planned for different buildings. They use ionization chambers for gamma-measuring. The measuring channels are self controlled with implemented test sources. The order of limit transgression at the detectors is registrated. The interpretation indicates the room of the radiation source, which is signaled by flash lights. Extensive radiation protection shieldings make detector-placing a complex problem with secondary gamma-radiation to be taken into account. Most of the appearing defects can easily be repaired by exchange of components. Some of them have been eliminated by technical modification. Redundancy prevents total system failure. Some false alarms occurred during the operation time of the alarm systems. The main reason is pulse induction, resulting from lightning strike. Measures to prevent such events have been taken, while further measures are being considered

Plan for IER-443 Testing of the Y-12 and AWE Criticality Accident Alarm System Detectors at the Godiva IV Burst Reactor

Energy Technology Data Exchange (ETDEWEB)

Scorby, J. C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hickman, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hudson, B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Garbett, S. [Atomic Weapons Establishment (AWE), Berkshire (United Kingdom); Auld, G. [Atomic Weapons Establishment (AWE), Berkshire (United Kingdom); Horrne, A. [Atomic Weapons Establishment (AWE), Berkshire (United Kingdom); Beller, T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Goda, J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Haught, C. [Y-12 National Security Complex, Oak Ridge, TN (United States); Woodrow, C. [Y-12 National Security Complex, Oak Ridge, TN (United States); Ward, D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-07-24

This document provides the scope and details of the “Plan for Testing the Y-12 and AWE Criticality Accident Alarm System Detectors at the Godiva IV Burst Reactor”. Due to the relative simplicity of the testing goals, scope, and methodology, the NCSP Manager approved execution of the test when ready. No preliminary CED-1 or final design CED-2 reports were required or issued. The test will subject Criticality Accident Alarm System (CAAS) detectors supplied by Y- 12 and AWE to very intense and short duration mixed neutron and gamma radiation fields. The goals of the test will be to (1) substantiate functionality, for both existing and newly acquired Y- 12 CAAS detectors, and (2) the ability of the AWE detectors to provide quality temporal dose information after a hypothetical criticality accident. ANSI/ANS-8.3.1997 states that the “system shall be sufficiently robust as to actuate an alarm signal when exposed to the maximum radiation expected”, which has been defined at Y-12, in Documented Safety Analyses (DSAs), to be a dose rate of 10 Rad/s. ANSI/ANS-8.3.1997 further states that “alarm actuation shall occur as a result of a minimum duration transient” which may be assumed to be 1 msec. The pulse widths and dose rates which will be achieved in this test will exceed these requirements. Pulsed radiation fields will be produced by the Godiva IV fast metal burst reactor at the National Criticality Experimental Research Center (NCERC) at the Nevada National Security Site (NNSS). The magnitude of the pulses and the relative distances to the detectors will be varied to afford a wide range of radiation fluence and pulse widths. The magnitude of the neutron and gamma fields will be determined by reactor temperature rise to fluence and dose conversions which have been previously established through extensive measurements performed under IER-147. The requirements for CAAS systems to detect and alarm under a “minimum accident of concern” as well as other

Framatome-ANP France UO2 fuel fabrication. Criticality safety analysis in the light of the JCO accident

International Nuclear Information System (INIS)

Doucet, M.; Zheng, S.; Mouton, J.; Porte, R.

2003-01-01

In France the 1999' Tokai Mura criticality accident in Japan had a big impact on the nuclear fuel manufacturing facility community. Moreover this accident led to a large public discussion about all the nuclear facilities. The French Safety Authorities made strong requirements to the industrials to revisit completely their safety analysis files mainly those concerning nuclear fuels treatments. The FRAMATOME-ANP production of its French low enriched (5 w/o) UO2 fuel fabrication plant (FBFC/Romans) exceeds 1000 metric tons a year. Special attention was given to the emergency evacuation plan that should be followed in case of a criticality accident. If a criticality accident happens, site internal and external radioprotection requirements need to have an emergency evacuation plan showing the different routes where the absorbed doses will be as low as possible for people. The French Safety Authorities require also an update of the old based neutron source term accounting for state of the art methodology. UO2 blenders units contain a large amount of dry powder strictly controlled by moderation; a hypothetical water leakage inside one of these apparatus is simulated by increasing the water content of the powder. The resulted reactivity insertion is performed by several static calculations. The French IRSN/CEA CRISTAL codes are used to perform these static calculations. The kinetic criticality code POWDER simulates the power excursion versus time and determines the consequent total energy source term. MNCP4B performs the source term propagation (including neutrons and gamma) used to determine the isodose curves needed to define the emergency evacuation plant. This paper deals with the approach FRAMATOME-ANP has taken to assess Safety Authorities demands using the more up to date calculation tools and methodology. (author)

JAERI's activities in JCO accident

International Nuclear Information System (INIS)

2000-09-01

The Japan Atomic Energy Research Institute (JAERI) was actively involved in a variety of technical supports and cooperative activities, such as advice on terminating the criticality condition, contamination checks of the residents and consultation services for the residents, as emergency response actions to the criticality accident at the uranium processing facility operated by the JCO Co. Ltd., which occurred on September 30, 1999. These activities were carried out in collaborative ways by the JAERI staff from the Tokai Research Establishment, Naka Fusion Research Establishment, Oarai Research Establishment, and Headquarter Office in Tokyo. As well, the JAERI was engaged in the post-accident activities such as identification of accident causes, analyses of the criticality accident, and dose assessment of exposed residents, to support the Headquarter for Accident Countermeasures of the Science and Technology Agency (STA), the Accident Investigation Committee and the Health Control Committee of the Nuclear Safety Commission of Japan (NSC). This report compiles the activities, that the JAERI has conducted to date, including the discussions on measures for terminating the criticality condition, evaluation of the fission number, radiation monitoring in the environment, dose assessment, analyses of criticality dynamics. (author)

Locations of criticality alarms and nuclear accident dosimeters at Hanford

International Nuclear Information System (INIS)

1992-08-01

Hanford facilities that contain fissionable materials capable of achieving critical mass are monitored with nuclear accident dosimeters (NADS) in compliance with the requirements of DOE Order 5480.11, Chapter XI, Section 4.c. (DOE 1988). The US Department of Energy (DOE) Richland Field Office (RL) has assigned the responsibility for maintaining and evaluating the Hanford NAD system to the Instrumentation and External Dosimetry (I ampersand ED) Section of Pacific Northwest Laboratory's (PNL's) Health Physics Department. This manual provides a description of the Hanford NAD, criteria and instructions for proper NAD placement, and the locations of these dosimeters onsite

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.

Source term analysis for a criticality accident in metal production line glove boxes

International Nuclear Information System (INIS)

Nguyen, D.H.

1991-06-01

A recent development in criticality accident analysis is the deterministic calculations of the transport of fission products and actinides through the barriers of the physical facility. The knowledge of the redistribution of the materials inside the facility will help determine the reentry and clean-up procedures. The amount of radioactive materials released to the environment is the source term for dispersion calculations. We have used an integrated computer model to determine the release of fission products to the environment from a hypothetical criticality event in a glove box of the metal production line (MPL) at the Lawrence Livermore National Laboratory (LLNL)

A Novel Thermal-Mechanical Detection System for Reactor Pressure Vessel Bottom Failure Monitoring in Severe Accidents

International Nuclear Information System (INIS)

Bi, Daowei; Bu, Jiangtao; Xu, Dongling

2013-06-01

Following the Fukushima Daiichi nuclear accident in Japan, there is an increased need of enhanced capabilities for severe accident management (SAM) program. Among others, a reliable method for detecting reactor pressure vessel (RPV) bottom failure has been evaluated as imperative by many utility owners. Though radiation and/or temperature measurement are potential solutions by tradition, there are some limitations for them to function desirably in such severe accident as that in Japan. To provide reliable information for assessment of accident progress in SAM program, in this paper we propose a novel thermal-mechanical detection system (TMDS) for RPV bottom failure monitoring in severe accidents. The main components of TMDS include thermally sensitive element, metallic cables, tension controlled switch and main control room annunciation device. With TMDS installed, there shall be a reliable means of keeping SAM decision-makers informed whether the RPV bottom has indeed failed. Such assurance definitely guarantees enhancement of severe accident management performance and significantly improve nuclear safety and thus protect the society and people. (authors)

SARTEMP2 - A computer program to calculate power and temperatures in a transport flask during a criticality accident

International Nuclear Information System (INIS)

Shaw, P.M.

1983-04-01

The computer code SARTEMP2, an extended version of the original SARTEMP program, which calculates the power and temperatures in a transport flask during a hypothetical criticality accident is described. The accident arises, it is assumed, during the refilling of the flask with water, bringing the system to delayed critical. As the water level continues to rise, reactivity is added causing the power to rise, and thus temperatures in the fuel, clad and water to increase. The point kinetics equations are coupled to the one-dimensional heat conduction equation. The model used, the method of solution of the equations and the input data required are given. (author)

Estimation of dose distribution and neutron spectra in JCO critical accident by shielding calculations

International Nuclear Information System (INIS)

Sakamoto, Yukio

2001-01-01

The information about neutrons at the surrounding of JCO site in the critical accident is limited to survey results by neutron Rem counter in the period of accident and activation data very near the test facility measured after the shut down of accident. This caused the big uncertainty in the dose estimation by detailed shielding calculation codes. On the other hand, environmental activity data measured by radiochemical researchers included the information about fast neutrons inside of JCO site and thermal neutrons up to 1 km from test facility. It is important to grasp the actual circumstance and examine the executed evaluation of the critical accident as scientifically as possible. Therefore, it is meaningful for different field researchers to corporate and exchange the information. In the Technical Divisions of Radiation Science and Technology in Atomic Energy Society of Japan, the information about neutron spectra are released from their home page and three groups of JAERI/CRC, Sumitomo Atomic Energy Industry and Nuclear Power Engineering Corp. (NUPEC)/Mitsubishi Research Institute Inc. (MRI), tried the shielding calculation by Monte Carlo Code MCNP-4B. The procedures and main results of shielding calculations were reviewed in this report. The main difference of shielding calculation by three groups was density and water content of autoclaved light-weight concrete (ALC) as the wall and ceiling. From the result by NUPEC/MRI, it was estimated that the water content in ALC was from 0.05 g/cm 3 to 0.10 g/cm 3 . The behavior of dose equivalent attenuation obtained by shielding calculation was very similar with the measured data from 250 m to 1,700 m obtained by survey meter, TLD and monitoring post. For more exact dose estimation, more detail examination of density and water content of ALC will be needed. (author)

Environment radiological monitoring by JNC related to the JCO criticality accident

International Nuclear Information System (INIS)

Watanabe, Hitoshi

2001-01-01

Concerning the criticality accident at JCO Co., Ltd. (JCO) which occurred at 10:35 on 30th Sep. 1999, Japan Nuclear Cycle Development Institute (JNC) established ''JNC's task force'' at 12:35 on the same data in conjunction with Head Office and Tokai Works. JNC's task force had collaborated on environmental radiological monitoring with the government of Japan and the local governments. This report compiles the results of the environmental monitoring performed by JNC's task force based on the request from the government of Japan and the local governments. (author)

Comparison of two simulation methods for testing of algorithms to detect cyclist and pedestrian accidents in naturalistic data

OpenAIRE

Madsen, Tanja; Christensen, Mads; Sloth Andersen, Camilla; Varhelyi, Andras; Laureshyn, Aliaksei; Moeslund, Thomas; Lahrmann, Harry

2017-01-01

Naturalistic studies can potentially be used to detect accidents of vulnerable road users and thus overcome the large degree of under-reporting in the official accident records. In this study, simulated cycling and walking accidents were performed by a stuntman and with a crash test dummy to test how they differ from each other and the potential implications of using simulated accidents as an alternative to real accidents. The study consisted of simulations of common accident types for cyclis...

Comparison of two simulation methods for testing of algorithms to detect cyclist and pedestrian accidents in naturalistic data

OpenAIRE

Madsen, Tanja Kidholm Osmann; Christensen, Mads Bock; Andersen, Camilla Sloth; Várhelyi, András; Laureshyn, Aliaksei; Moeslund, Thomas B.; Lahrmann, Harry Spaabæk

2017-01-01

Naturalistic studies can potentially be used to detect accidents of vulnerable road users and thus overcome the large degree of under-reporting in the official accident records. In this study, simulated cycling and walking accidents were performed by a stunt man and with a crash test dummy to test how they differ from each other and the potential implications of using simulated accidents as an alternative to real accidents. The study consisted of simulations of common accident types for cycli...

Precautions for preventing criticality at plutonium fuel treatment facilities

International Nuclear Information System (INIS)

Deworm, J.P.; Fieuw, G.; Cank, H. de

1976-01-01

Four criticality accidents took place between 1958 and 1964 at fuel processing plants using wet methods. So far accident of this type has taken place at production units where fissionable material is used. The prevention of criticality is one of the major concerns of the officials in charge of the plutonium fuel research laboratories operated at the Mol Nuclear Energy Study Centre by the SCK/CEN-Belgonucleaire Association. The means of preventing such an accident are of three types: introducing different types of treatment in well-defined work units; thorough analysis of planned experiments or fabrication programmes to determine the sub-criticality factors; application of technical and administrative procedures which ensure that the facilities are always sub-critical during the treatment and storage of fissionable materials. The installation includes a detection and warning system and provision is made for the immediate evacuation of staff should a crticality incident occur. The effects of a critical excursion on the building have been assessed. (author)

Criticality accident in uranium fuel processing plant. Cause analysis and teachings from a viewpoint of a human factor

International Nuclear Information System (INIS)

Furuta, Kazuo

2000-01-01

On the JCO criticality accident occurred on September 30, 1999, from relatively earlier time since its occurrence it was elucidated that it was formed not by accident and error operation of apparatus and instruments but by unsafe actions of operators beyond regular manual as its direct cause, and that an organizational factor on business managers and safety administration unable to control such unsafe actions of operators at its background. Then, it was judged to be essential to carry out an accident research from a viewpoint of the human factor (HF) for elucidation on essence of the accident, to establish a 'special workshop on the JCO accident research' to investigate elucidation of the accident cause and countermeasure of reoccurrence at a standpoint of HF. As a result, the essential cause of this accident was summarized that safety information such as ideals, information, teachings and so forth necessary for safety management were failed to share among different organizations. As a teaching of this accident, nuclear energy participants must recognize that safety culture is not finished only in specific organization and range but produced by protecting weathering of danger consciousness and effort of mutually exciting and learning by sharing a safety information beyond different organization, range and time. (G.K.)

Research on consequence analysis method for probabilistic safety assessment of nuclear fuel facilities (5). Evaluation method and trial evaluation of criticality accident

International Nuclear Information System (INIS)

Yamane, Yuichi; Abe, Hitoshi; Nakajima, Ken; Hayashi, Yoshiaki; Arisawa, Jun; Hayami, Satoru

2010-01-01

A special committee of 'Research on the analysis methods for accident consequence of nuclear fuel facilities (NFFs)' was organized by the Atomic Energy Society of Japan (AESJ) under the entrustment of Japan Atomic Energy Agency (JAEA). The committee aims to research on the state-of-the-art consequence analysis method for the Probabilistic Safety Assessment (PSA) of NFFs, such as fuel reprocessing and fuel fabrication facilities. The objectives of this research are to obtain information useful for establishing quantitative performance objectives and to demonstrate risk-informed regulation through qualifying issues needed to be resolved for applying PSA to NFFs. The research activities of the committee were mainly focused on the consequence analysis method for postulated accidents with potentially large consequences in NFFs, e.g., events of criticality, spill of molten glass, hydrogen explosion, boiling of radioactive solution and fire (including the rapid decomposition of TBP complexes), resulting in the release of radioactive materials to the environment. The results of the research were summarized in a series of six reports, which consist of a review report and five technical ones. In this report, the evaluation methods of criticality accident, such as simplified methods, one-point reactor kinetics codes and quasi-static method, were investigated and their features were summarized to provide information useful for the safety evaluation of NFFs. In addition, several trial evaluations were performed for a hypothetical scenario of criticality accident using the investigated methods, and their results were compared. The release fraction of volatile fission products in a criticality accident was also investigated. (author)

Determination of gamma-ray exposure rate from short-lived fission products under criticality accident conditions

International Nuclear Information System (INIS)

Yanagisawa, Hiroshi; Ohno, Akio; Aizawa, Eijyu

2002-01-01

For the assessment of γ-ray doses from short-lived fission products (FPs) under criticality accident conditions, γ-ray exposure rates varying with time were experimentally determined in the Transient Experiment Critical Facility (TRACY). The data were obtained by reactivity insertion in the range of 1.50 to 2.93$. It was clarified from the experiments that the contribution of γ-ray from short-lived FPs to total exposure during the experiments was evaluated to be 15 to 17%. Hence, the contribution cannot be neglected for the assessment of γ-ray doses under criticality accident conditions. Computational analyses also indicated that γ-ray exposure rates from short-lived FPs calculated with the Monte Carlo code, MCNP4B, and photon sources based on the latest FP decay data, the JENDL FP Decay Data File 2000, well agreed with the experimental results. The exposure rates were, however, extremely underestimated when the photon sources were obtained by the ORIGEN2 code. The underestimation is due to lack of energy-dependent photon emission data for major short-lived FP nuclides in the photon database attached to the ORIGEN2 code. It was also confirmed that the underestimation arose in 1,000 or less of time lapse after an initial power burst. (author)

Prevention of criticality accidents

International Nuclear Information System (INIS)

Canavese, S.I.

1982-01-01

These notes used in the postgraduate course on Radiological Protection and Nuclear Safety discuss macro-and microscopic nuclear constants for fissile materials systems. Critical systems: their definition; criteria to analyze the critical state; determination of the critical size; analysis of practical problems about prevention of criticality. Safety of isolated units and of sets of units. Application of standards. Conception of facilities from the criticality control view point. (author) [es

Airway accidents in critical care unit: A 3-year retrospective study in a Public Teaching Hospital of Eastern India

Science.gov (United States)

Dasgupta, Sugata; Singh, Shipti Shradha; Chaudhuri, Arunima; Bhattacharya, Dipasri; Choudhury, Sourav Das

2016-01-01

Background: Although tracheal tubes are essential devices to control and protect airway in a critical care unit (CCU), they are not free from complications. Aims: To document the incidence and nature of airway accidents in the CCU of a government teaching hospital in Eastern India. Methods: Retrospective analysis of all airway accidents in a 5-bedded (medical and surgical) CCU. The number, types, timing, and severity of airway accidents were analyzed. Results: The total accident rate was 19 in 233 intubated and/or tracheostomized patients over 1657 tube days (TDs) during 3 years. Fourteen occurred in 232 endotracheally intubated patients over 1075 endotracheal tube (ETT) days, and five occurred in 44 tracheostomized patients over 580 tracheostomy TDs. Fifteen accidents were due to blocked tubes. Rest four were unplanned extubations (UEs), all being accidental extubations. All blockages occurred during night shifts and all UEs during day shifts. Five accidents were mild, the rest moderate. No major accident led to cardiorespiratory arrest or death. All blockages occurred after 7th day of intubation. The outcome of accidents were more favorable in tracheostomy group compared to ETT group (P = 0.001). Conclusions: The prevalence of airway accidents was 8.2 accidents per 100 patients. Blockages were the most common accidents followed by UEs. Ten out of the 15 blockages and all 4 UEs were in endotracheally intubated patients. Tracheostomized patients had 5 blockages and no UEs. PMID:27076709

JAERI's activities in JCO accident

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-09-01

The Japan Atomic Energy Research Institute (JAERI) was actively involved in a variety of technical supports and cooperative activities, such as advice on terminating the criticality condition, contamination checks of the residents and consultation services for the residents, as emergency response actions to the criticality accident at the uranium processing facility operated by the JCO Co. Ltd., which occurred on September 30, 1999. These activities were carried out in collaborative ways by the JAERI staff from the Tokai Research Establishment, Naka Fusion Research Establishment, Oarai Research Establishment, and Headquarter Office in Tokyo. As well, the JAERI was engaged in the post-accident activities such as identification of accident causes, analyses of the criticality accident, and dose assessment of exposed residents, to support the Headquarter for Accident Countermeasures of the Science and Technology Agency (STA), the Accident Investigation Committee and the Health Control Committee of the Nuclear Safety Commission of Japan (NSC). This report compiles the activities, that the JAERI has conducted to date, including the discussions on measures for terminating the criticality condition, evaluation of the fission number, radiation monitoring in the environment, dose assessment, analyses of criticality dynamics. (author)

Criticality incident detection assessment methodology

International Nuclear Information System (INIS)

Haley, Richard M.; Warburton, Simon J.; Bowden, Russell L.

2003-01-01

In the United Kingdom, all nuclear facilities that handle, treat or store fissile material require a Criticality Incident Detection and Alarm System (CIDAS) to be installed, unless a case is made for the omission of such a system. Where it is concluded that a CIDAS is required, the primary objective is the reliable detection of criticality and the initiation of prompt evacuation of plant workers from the vicinity of the incident. This paper will examine and compare various methods that can be used to demonstrate that a CIDAS will satisfy the detection criterion. The paper will focus on fit-for-purpose and cost-effective methods for the assessment of gamma-based systems. In the experience of the authors this is particularly useful in demonstrating the efficacy of existing systems in operational plant. (author)

A cost effective approach for criticality accident analysis of a DOE SNF storage facility

International Nuclear Information System (INIS)

Garrett, R.L.; Couture, G.F.; Gough, S.T.

1997-01-01

This paper presents the methodologies used to derive criticality accident analyses for a spent nuclear fuel receipt, storage, handling, and shipping facility. Two criticality events are considered: process-induced and Natural Phenomena Hazards (NPH)-induced. The criticality analyses required the development of: (1) the frequency at which each sceanario occurred, (2) the estimated number of fissions for each scenario, and (3) the consequences associated with each criticality scenario. A fault tree analysis was performed to quantify the frequency of criticality due to process-induced events. For the frequency analysis of NPH-induced criticality, a probabilistic approach was employed. To estimate the consequences of a criticality event, the resulting fission yield was determined using a probabilistic approach. For estimating the source term, a 95% amount of overall conservatism was targeted. This methodology applied to the facility criticality scenarios indicated that: (1) the 95th percentile yield levels from the historical yield distributions are approximately 5 x 10 17 fissions and 5 x 10 18 fissions for internal event and NPH-induced criticality event, respectively; and (2) using probabilistic Latin Hypercube Sampling, the downwind 95th percentile dose to a receptor at the US DOE reservation boundary is 2.2 mrem. This estimate is compared to the bounding dose of 1.4 rem. 4 refs., 1 fig

The JCO criticality accident at Tokai-mura, Japan: an overview of the sampling campaign and preliminary results

International Nuclear Information System (INIS)

Komura, K.; Yamamoto, M.; Muroyama, T.; Murata, Y.; Nakanishi, T.; Hoshi, M.; Takada, J.; Ishikawa, M.; Takeoka, S.; Kitagawa, K.; Suga, S.; Endo, S.; Tosaki, N.; Mitsugashira, T.; Hara, M.; Hashimoto, T.; Takano, M.; Yanagawa, Y.; Tsuboi, T.; Ichimasa, M.; Ichimasa, Y.; Imura, H.; Sasajima, E.; Seki, R.; Saito, Y.; Kondo, M.; Kojima, S.; Muramatsu, Y.; Yoshida, S.; Shibata, S.; Yonehara, H.; Watanabe, Y.; Kimura, S.; Shiraishi, K.; Ban-nai, T.; Sahoo, S.K.; Igarashi, Y.; Aoyama, M.; Hirose, K.; Uehiro, T.; Doi, T.; Tanaka, A.; Matsuzawa, T.

2000-01-01

A criticality accident occurred on September 30, 1999 at the uranium conversion facility of the JCO Company Ltd. in Tokai-mura, Japan. A collaborating scientific investigation team was organized in two groups, the first to carry out research on the environmental impact (the environmental research group) and the second to assess the radiation effects on residents (the biological research group). This report concerns only the activities of the environmental research group. Four investigative teams were sent on different dates to the accident site and its vicinity to collect samples. About 400 samples were collected and subjected to analysis. An outline of the sampling campaign is presented here along with a brief chronology of the accident and the preliminary key results obtained by the independent research group are summarised in this Special Issue of the Journal of Environmental Radioactivity

A micro-gap, air-filled ionisation chamber as a detector for criticality accident dosimetry

International Nuclear Information System (INIS)

Murawski, I.; Zielczynski, M.; Gryzinski, M.A.; Golnik, N.

2014-01-01

A micro-gap air-filled ionisation chamber was designed for criticality dosimetry. The special feature of the chamber is its very small gap between electrodes of only 0.3 mm. This prevents ion recombination at high dose rates and minimises the influence of gas on secondary particles spectrum. The electrodes are made of polypropylene because of higher content of hydrogen in this material, when compared with soft tissue. The difference between neutron and gamma sensitivity in such chamber becomes practically negligible. The chamber's envelope contains two specially connected capacitors, one for polarising the electrodes and the other for collecting the ionisation charge. Air-filled ionisation chamber with very small gap is a simple dosemeter, which fulfills the most desired properties of criticality accident dosemeters. Short ion collection time is achieved by combination of small gap and relatively high polarising voltage. For the same reason, parasitic recombination of ions in the chamber is negligibly small even at high dose rates. The difference between neutron and gamma sensitivity is small for tissue-equivalent chamber and is expected to become practically negligible when the chamber electrodes are made of polypropylene. Additional capacitor provides a broad measuring range from ∼0.1 Gy up to ∼25 Gy; however, leakage of electrical charge from polarising capacitor has to be observed and taken into account. Periodical re-charging of the device is necessary. Obviously, final test of the device in conditions simulating criticality accident is needed and will be performed as soon as available. (authors)

Major Accidents (Gray Swans) Likelihood Modeling Using Accident Precursors and Approximate Reasoning.

Science.gov (United States)

Khakzad, Nima; Khan, Faisal; Amyotte, Paul

2015-07-01

Compared to the remarkable progress in risk analysis of normal accidents, the risk analysis of major accidents has not been so well-established, partly due to the complexity of such accidents and partly due to low probabilities involved. The issue of low probabilities normally arises from the scarcity of major accidents' relevant data since such accidents are few and far between. In this work, knowing that major accidents are frequently preceded by accident precursors, a novel precursor-based methodology has been developed for likelihood modeling of major accidents in critical infrastructures based on a unique combination of accident precursor data, information theory, and approximate reasoning. For this purpose, we have introduced an innovative application of information analysis to identify the most informative near accident of a major accident. The observed data of the near accident were then used to establish predictive scenarios to foresee the occurrence of the major accident. We verified the methodology using offshore blowouts in the Gulf of Mexico, and then demonstrated its application to dam breaches in the United Sates. © 2015 Society for Risk Analysis.

Criticality accident in uranium fuel processing plant. Emergency medical care and dose estimation for the severely overexposed patients

Energy Technology Data Exchange (ETDEWEB)

Akashi, Makoto; Ishigure, Nobuhito [National Inst. of Radiological Sciences, Chiba (Japan)

2000-08-01

A criticality accident occurred in JCO, a plant for nuclear fuel production in 1999 and three workers were exposed to extremely high-level radiation (neutron and {gamma}-ray). This report describes outlines of the clinical courses and the medical cares for the patients of this accident and the emergent medical system for radiation accident in Japan. One (A) of the three workers of JCO had vomiting and diarrhea within several minutes after the accident and another one (B) had also vomiting within one hour after. Based on these evidences, the exposure dose of A and B were estimated to be more than 8 and 4 GyEq, respectively. Generally, acute radiation syndrome (ARS) is assigned into three phases; prodromal phase, critical or manifestation phase and recovery phase or death. In the prodromal phase, anorexia, nausea, vomiting and diarrhea often develop, whereas the second phase is asymptotic. In the third phase, various syndromes including infection, hemorrhage, dehydration shock and neurotic syndromes are apt to occur. It is known that radiation exposure at 1 Gy or more might induce such acute radiation syndromes. Based on the clinical findings of Chernobyl accident, it has been thought that exposure at 0.5 Gy or more causes a lowering of lymphocyte level and a decrease in immunological activities within 48 hours. Lymphocyte count is available as an indicator for the evaluation of exposure dose in early phase, but not in later phase The three workers of JCO underwent chemical analysis of blood components, chromosomal analysis and analysis of blood {sup 24}Na immediately after the arrival at National Institute of Radiological Sciences via National Mito Hospital specified as the third and the second facility for the emergency medical care system in Japan, respectively. (M.N.)

Effects of the criticality accident at Tokai-mura on the public's attitude to nuclear power generation

International Nuclear Information System (INIS)

Kitada, Atsuko; Hayashi, Chikio

2000-01-01

The objective of our study was to clarify the effects on the public's attitude of nuclear power and the criticality accident that occurred at the JCO plant in Tokai-mura, Ibaraki Prefecture. For this purpose, we conducted an awareness survey in the Kansai and Kanto areas two months after the accident. Analysis was made on the basis of the comparison of the survey results with the data that the Institute of Nuclear Safety System had accumulated through continuous awareness surveys on nuclear power generation (regular surveys) since 1993. The public's reactions were twofold. On one hand, there were emotional reactions about accidents in nuclear facilities and a reduction in the sense of security. On the other hand, there were reactions concerning the image of nuclear power plant workers and demand on electricity utilities for enhanced employee education and training. The latter reactions correspond to the problems pointed out after the JCO accident. Regarding the utilization of nuclear power generation, the opinion that 'the utilization of nuclear power generation is unavoidable' accounts for 60% of those surveyed. With the opinion that 'nuclear power generation should be utilized' added, 70% of those surveyed take an affirmative attitude to nuclear power utilization. This situation has remained about the same since 1998, the year before the JCO accident. Using the quantification method III to analyze a number of questionnaires about nuclear power generation such as the anxiety about it, we determined overall attitude indexes regarding nuclear power to perform a time sequence comparison. The comparison shows that the attitude after the JCO accident tended to be more negative than in 1998. However, no significant difference in the overall indexes is seen between 1993 and 1998. Judging the comparison results on the basis of the time span starting in 1993 allows us to conclude that the JCO accident has not greatly contributed to worsening the attitude towards nuclear

EDAC, a detection and criticality alarm system. Physical and electronic characteristics (French patent no. 2184399, December 1974)

International Nuclear Information System (INIS)

Prigent, Raymond; Renard, Claude.

1976-10-01

A project of investigations (CRAC project) conducted around 1970 brought new conclusions on accident characteristics. These conclusions were at the origin of a new philosophy of detection that resulted in the development of a detection probe sensitive both to neutrons and gamma with a response representative of the dose received by the exposed individuals. To meet these criteria, the main components of the probe are a plastic and a boron scintillators optically and mechanically connected to a photo-emissive cell, the whole being surrounded with a polyethylene casing. The characteristics of these various elements have been determined experimentally in order to get a balanced response; the chief experimental results are described. The information from the probes are collected in a processing unit with characteristics meeting the critically safety commission specifications [fr

An emergent proposal on the Committee of Uranium Processing Factory Criticality Accident Survey of the Nuclear Safety Commission. A meantime report dated on November 5, 1999

International Nuclear Information System (INIS)

2000-01-01

The Nuclear Safety Commission was received a decision on thorough investigations of accident reason on criticality accident at the Tokai-mura uranium processing factory of the JCO Incorporation occurred on September 30, 1999, to establish the Committee of Uranium Processing Factory Criticality Accident Survey to elucidate its reason thoroughly and contribute to set up a sufficient reforming prevention countermeasure. This Committee judged that it was important to propose a countermeasure directly obtainable by grasping some fact relations clarified before now as soon as possible and intended to conduct this meantime report of 'emergent proposal' by arrangement of such fact relations. Here were described on accidental conditions and their effects, response to the accident (on prevention of the accident), its reasons and their relating conditions, and some emergent proposals. In the last items, safety security at accidental site, health countermeasures to residents and others, establishment of safety security for nuclear business workers and others, and reconstruction on safety regulation in national government. (G.K.)

Transactions of the criticality alarm systems workshop

International Nuclear Information System (INIS)

1988-01-01

The first Criticality Alarm workshop was held by the US Department of Energy Albuquerque Operations Office in 1985. This second workshop is the first held on an international level. There were 98 persons in attendance. They represented the Department of Energy (DOE) field offices, DOE contractors, the Nuclear Regulatory Commission (NRC), NRC licensees, and agencies in the United Kingdom, France, West Germany, and Japan. Topics were on practices experience, and development. A key value of the workshop was the sharing of critical alarm system experiences, problems, and advances in the state of the art. In addition, several Criticality Alarm Systems (CAS) equipment systems were exhibited. Papers were presented on: nature of criticality accidents; lessons learned from past accidents; application of ANS 8.3 standard; gamma and neutron detection systems; research and development in progress; testing at Oak Ridge and Los Alamos; methods used to place detectors; centralized readout feature; false alarms; trip-point settings; and testing and maintenance. The individual papers have been cataloged separately

Accident precursors, near misses, and warning signs: Critical review and formal definitions within the framework of Discrete Event Systems

International Nuclear Information System (INIS)

Saleh, Joseph H.; Saltmarsh, Elizabeth A.; Favarò, Francesca M.; Brevault, Loïc

2013-01-01

An important consideration in safety analysis and accident prevention is the identification of and response to accident precursors. These off-nominal events are opportunities to recognize potential accident pathogens, identify overlooked accident sequences, and make technical and organizational decisions to address them before further escalation can occur. When handled properly, the identification of precursors provides an opportunity to interrupt an accident sequence from unfolding; when ignored or missed, precursors may only provide tragic proof after the fact that an accident was preventable. In this work, we first provide a critical review of the concept of precursor, and we highlight important features that ought to be distinguished whenever accident precursors are discussed. We address for example the notion of ex-ante and ex-post precursors, identified for postulated and instantiated (occurred) accident sequences respectively, and we discuss the feature of transferability of precursors. We then develop a formal (mathematical) definition of accident precursors as truncated accident sequences within the modeling framework of Discrete Event Systems. Additionally, we examine the related notions of “accident pathogens” as static or lurking adverse conditions that can contribute to or aggravate an accident, as well as “near misses”, “warning signs” and the novel concept of “accident pathway”. While these terms are within the same linguistic neighborhood as “accident precursors”, we argue that there are subtle but important differences between them and recommend that they not be used interchangeably for the sake of accuracy and clarity of communication within the risk and safety community. We also propose venues for developing quantitative importance measures for accident precursors, similar to component importance measures in reliability engineering. Our objective is to establish a common understanding and clear delineation of these terms, and

Early clinical consequences of victims in JCO criticality accident in Tokaimura

International Nuclear Information System (INIS)

Suzuki, Gen

2000-01-01

The JCO criticality accident occurred at 10:35 on September 30, 1999 when two workers (O and S) poured the solution of uranyl nitrate into the precipitation tank and one (Y) worked at desk in the neighboring room. O's symptoms were unconsciousness, rigidity and emesis, and S's, numbness. The three were moved to Mito National Hospital by an ambulance car at 12:07 and then to the Hospital of National Institute of Radiological Sciences by the helicopter and car at 15:25, where contamination of their cloths by Na-24, suggesting the exposure to neutron, was found. O exhibited emesis within 10 min after the accident and diarrhea, unconsciousness and severe pyrexia within 1 hr, suggesting he had undergone the lethal exposure of >8 Gy. S showed emesis, light unconsciousness and numbness within 1 hr, suggesting >6 Gy and Y did not show even emesis, less dose exposure than the two. They underwent firstly the drip of sodium hydrogen carbonate (due to possible internal exposure of uranium), oxygen inhalation and then corticoid injection as well as the drip of antibiotics. At that day, they had the special therapy with pentoxyphylline and L-glutamine+elementary diet. Later, in the Hospital of Tokyo University, O and S had the heamopoietic stem cell transplantation. At present, O passed away, S is still in hospital and Y is discharged. (K.H.)

A Detection Device for the Signs of Human Life in Accident

Science.gov (United States)

Ning, Li; Ruilan, Zhang; Jian, Liu; Ruirui, Cheng; Yuhong, Diao

2017-12-01

A detection device for the signs of human life in accidents is a device used in emergency situations, such as the crash site. the scene of natural disasters, the battlefield ruins. it designed to detect the life signs of the distress under the injured ambulance vital signs devices. The device can on human vital signs, including pulse, respiration physiological signals to make rapid and accurate response. After some calculations, and after contrast to normal human physiological parameters given warning signals, in order for them to make timely ambulance judgment. In this case the device is required to do gymnastics convenience, ease of movement, power and detection of small flexible easy realization. This device has the maximum protection of the wounded safety significance.

Radiation accidents

International Nuclear Information System (INIS)

Poplavskij, K.K.; Smorodintseva, G.I.

1978-01-01

On the basis of a critical analysis of the available data on causes and consequences of radiation accidents (RA), a classification of RA by severity (five groups of accidents) according to biomedical consequences and categories of exposed personnel is proposed. A RA is defined and its main characteristics are described. Methods of RA prevention are proposed, as is a plan of specific measures to deal with RA in accordance with the proposed classification

Reactivity accident analysis in MTR cores

International Nuclear Information System (INIS)

Waldman, R.M.; Vertullo, A.C.

1987-01-01

The purpose of the present work is the analysis of reactivity transients in MTR cores with LEU and HEU fuels. The analysis includes the following aspects: the phenomenology of the principal events of the accident that takes place, when a reactivity of more than 1$ is inserted in a critical core in less than 1 second. The description of the accident that happened in the RA-2 critical facility in September 1983. The evaluation of the accident from different points of view: a) Theoretical and qualitative analysis; b) Paret Code calculations; c) Comparison with Spert I and Cabri experiments and with post-accident inspections. Differences between LEU and HEU RA-2 cores. (Author)

A NPO project for measurement of environmental neutrons in the peninsula Shimokita after the JCO criticality accident

International Nuclear Information System (INIS)

Aratani, Michi

2001-01-01

. He has already successfully detected various radioactive nuclides activated by environmental neutrons of natural level using extremely low background gamma ray spectrometers located in the Ogoya Underground Laboratory. At the JCO accident, he applied his method to samples irradiated in the jewelry boxes, chests, and kitchens in the houses near the accident point by the accidental neutrons. Golden jewelries were borrowed for measurement by the low background gamma ray spectrometers in Ogoya, and the neutron flux at the criticality was obtained. The members of SAS and EGG as audiences of the IES Seminar were deeply impressed with the lecture, especially, simplicity of the method, and they were eager for measurement of natural neutron level in their own environment, Penin. Shimokita. Soon afterwards they visited Ogoya and asked Prof. Komura to help them measure their environmental neutron flux. They applied to the Fund of Aomori Prefecture, Blue Woods Fund, and won 3,000,000 yen during coming 3 years for their theme containing environmental neutron measurement. Discussion: The news of their winning of Blue Woods Fund, Aomori Prefecture, for their theme of environmental neutron measurement seems us to be a bolt out of the blue at preset stage of scientific culture of our country, because it might suggest a beginning of science of the people, science by the people, and science for the people. The situation may suggest a maturity of scientific culture in this region over arguments pro and con regarding the policy for nuclear energy development in the Penin. Shimokita. The global environment may be thought to have attained to a saturation condition. Our society is full of goods. Science and technology for production of goods have been already past culture. Coming science should be science for pleasure and refreshment of human mind as well as various arts, for example, music, picture, sculpture, drama, and literature. (author)

Measurement of the Portsmouth Gaseous Diffusion Plant criticality accident alarm

International Nuclear Information System (INIS)

Tayloe, R.W. Jr.; McGinnis, B.

1990-01-01

Measurements of the Portsmouth Gaseous Diffusion Plant's nuclear criticality accident radiation alarm signal response time, sound wave frequency, and sound volume levels were made to demonstrate compliance with ANSI/ANS-8.3-1986. A steady-state alarm signal is produced within one-half second of obtaining a two-out-of-three detector trip. The fundamental alarm sound wave frequency is 440 hertz. The sound volume levels are greater than 10 decibels above background and ranged from 100 to 125 A-weighted decibels. The requirements of the standard were met; however the recommended maximum sound volume level of 115 dBA was exceeded. Emergency procedures require immediate evacuation upon initiation of a facility's radiation alarm. Comparison with standards for allowable time of exposure at different noise levels indicate that the elevated noise level at this location does not represent an occupational injury hazard. 8 refs., 5 figs

Comparison of the transient behavior of lead-based advanced critical and sub-critical reactors

International Nuclear Information System (INIS)

Wang Gang; Gu Zhixing; Wang Zhen; Jin Ming; Bai Yunqing

2014-01-01

A lead-based reactor developed by FDS Team is proposed in 2011 and designed to be 10 MW. It is a pool type reactor and the primary coolant is driven by natural circulation. The reactor has two operation modes, which are a lead-based critical fast reactor mode and a lead-based sub-critical reactor mode. The conceptual designs of the two modes are both completed by 2013. In this paper, four transient accidents were simulated for both the critical and sub-critical reactors above by NTC-2D code, which is developed by FDS Team for advanced reactor safety analysis. The four accidents were protected and unprotected loss of heat sink accidents (PLOHS and ULOHS), protected and unprotected transient overpower accidents (PTOP and UTOP). The simulation results of the two reactors were compared and analyzed. The results showed that during PLOHS and PTOP accidents for both the two modes, all the key parameters (core power, fuel, cladding and coolant temperatures in the hottest channel) decreased to very small values after the reactor scrammed, which meant the reactors under the two modes were both safe. For ULOHS, the fuel, cladding and coolant temperatures of the sub-critical reactor increased bigger than those of the critical one. For UTOP, the parameters above of the critical fast reactor were much bigger than those of the sub-critical one. The analysis results showed different safety advantages of the lead-based critical fast and sub-critical reactors during different transient accidents. (author)

A virtual environment for simulation of radiological accidents

International Nuclear Information System (INIS)

Silva, Tadeu Augusto de Almeida; Farias, Oscar Luiz Monteiro de

2013-01-01

A virtual environment is a computer environment, representative of a subset of the real world, and where models of the real world entities, process and events are included in a virtual (three-dimensional) space. Virtual environments are ideal tools for simulation of certain critical processes, such as radiological accidents, where human beings or properties can suffer irreversible or long term damages. Radiological accidents are characterized by the significant exposure to radiation of specialized workers and general public. The early detection of a radiological accident and the determination of its possible extension are essential factors for the planning of prompt answers and emergency actions. This paper proposes the integration of georeferenced representation of the three-dimensional space and agent-based models, with the objective to construct virtual environments that have the capacity to simulate radiological accidents. The three-dimensional georeferenced representations of space candidates are: 1) the spatial representation of traditional geographical information systems (GIS); 2) the representation adopted by Google Maps®. Adding agents to these spatial representations allow us to simulate radiological accidents, quantify the doses received by members of the public, obtain a possible spatial distribution of people contaminated, estimate the number of contaminated individuals, estimate the impact on the health-network, estimate environmental impacts, generate exclusion zones, build alternative scenarios and train staff to deal with radiological accidents. (author)

A virtual environment for simulation of radiological accidents

Energy Technology Data Exchange (ETDEWEB)

Silva, Tadeu Augusto de Almeida, E-mail: tedsilva@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Farias, Oscar Luiz Monteiro de, E-mail: fariasol@eng.uerj.br [Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil)

2013-07-01

A virtual environment is a computer environment, representative of a subset of the real world, and where models of the real world entities, process and events are included in a virtual (three-dimensional) space. Virtual environments are ideal tools for simulation of certain critical processes, such as radiological accidents, where human beings or properties can suffer irreversible or long term damages. Radiological accidents are characterized by the significant exposure to radiation of specialized workers and general public. The early detection of a radiological accident and the determination of its possible extension are essential factors for the planning of prompt answers and emergency actions. This paper proposes the integration of georeferenced representation of the three-dimensional space and agent-based models, with the objective to construct virtual environments that have the capacity to simulate radiological accidents. The three-dimensional georeferenced representations of space candidates are: 1) the spatial representation of traditional geographical information systems (GIS); 2) the representation adopted by Google Maps®. Adding agents to these spatial representations allow us to simulate radiological accidents, quantify the doses received by members of the public, obtain a possible spatial distribution of people contaminated, estimate the number of contaminated individuals, estimate the impact on the health-network, estimate environmental impacts, generate exclusion zones, build alternative scenarios and train staff to deal with radiological accidents. (author)

Studying Irony Detection Beyond Ironic Criticism: Let's Include Ironic Praise

Directory of Open Access Journals (Sweden)

Richard Bruntsch

2017-04-01

Full Text Available Studies of irony detection have commonly used ironic criticisms (i.e., mock positive evaluation of negative circumstances as stimulus materials. Another basic type of verbal irony, ironic praise (i.e., mock negative evaluation of positive circumstances is largely absent from studies on individuals' aptitude to detect verbal irony. However, it can be argued that ironic praise needs to be considered in order to investigate the detection of irony in the variety of its facets. To explore whether the detection ironic praise has a benefit beyond ironic criticism, three studies were conducted. In Study 1, an instrument (Test of Verbal Irony Detection Aptitude; TOVIDA was constructed and its factorial structure was tested using N = 311 subjects. The TOVIDA contains 26 scenario-based items and contains two scales for the detection of ironic criticism vs. ironic praise. To validate the measurement method, the two scales of the TOVIDA were experimentally evaluated with N = 154 subjects in Study 2. In Study 3, N = 183 subjects were tested to explore personality and ability correlates of the two TOVIDA scales. Results indicate that the co-variance between the ironic TOVIDA items was organized by two inter-correlated but distinct factors: one representing ironic praise detection aptitude and one representing ironic criticism detection aptitude. Experimental validation showed that the TOVIDA items truly contain irony and that item scores reflect irony detection. Trait bad mood and benevolent humor (as a facet of the sense of humor were found as joint correlates for both ironic criticism and ironic praise detection scores. In contrast, intelligence, trait cheerfulness, and corrective humor were found as unique correlates of ironic praise detection scores, even when statistically controlling for the aptitude to detect ironic criticism. Our results indicate that the aptitude to detect ironic praise can be seen as distinct from the aptitude to detect ironic

Local governments' roles of the compensation for damage by the Tokai JCO criticality accident

International Nuclear Information System (INIS)

Tanabe, Tomoyuki

2003-01-01

The Tokai JCO criticality accident on September 30, 1999 was the first case to which The Law on Compensation for Nuclear Damage was applied. Although the Law on Compensation for Nuclear Damage formulates the outline of the institutional framework for nuclear third party liability together with operator's insurance scheme, details of actual compensation procedure are not specified. By this reason, the compensation procedure in the Tokai accident had been executed without a concrete legal specification and a precedent. In spite of this situation, the compensation procedure with the accident led to an unexpectedly successful result. We observe the several reasons why the compensation procedure was implemented successfully despite the lack of concrete legal specification and a precedent. One of the reasons is that the local governments, Tokai Village and Ibaraki Prefecture, immediately took the leadership in implementing a temporary regime of compensation procedure without wasting time for waiting national government's directives. Upon practicing this compensation procedure, the local governments implemented the following steps. (1) Initial estimation of the amount and scope of damage. (2) Providing the criteria and heads of damage subject to compensation. (3) Unitary compensation procedure at the local levels. (4) Distribution of emergency payments for the victims. (5) Facilitating compensatory negotiation between the victims and JCO as arbitrator. However, some concerns are also pointed out about the fact that the local government directed the whole procedure without sufficient adjustment with the national government for compensation policy. Among all, in the compensation led by the local governments, it was difficult to guarantee fairness of compensation because victims who are influential on the local government such as industrial associations would have unfairly strong negotiation power in the compensatory negotiation, while the operator being responsible for the

Review of current status for designing severe accident management support system

Energy Technology Data Exchange (ETDEWEB)

Jeong, Kwang Sub

2000-05-01

The development of operator support system (OSS) is ongoing in many other countries due to the complexity both in design and in operation for nuclear power plant. The computerized operator support system includes monitoring of some critical parameters, early detection of plant transient, monitoring of component status, plant maintenance, and safety parameter display, and the operator support system for these areas are developed and are being used in some plants. Up to now, the most operator support system covers the normal operation, abnormal operation, and emergency operation. Recently, however, the operator support system for severe accident is to be developed in some countries. The study for the phenomena of severe accident is not performed sufficiently, but, based on the result up to now, the operator support system even for severe accident will be developed in this study. To do this, at first, the current status of the operator support system for normal/abnormal/emergency operation is reviewed, and the positive aspects and negative aspects of systems are analyzed by their characteristics. And also, the major items that should be considered in designing the severe accident operator support system are derived from the review. With the survey of domestic and foreign operator support systems, they are reviewed in terms of the safety parameter display system, decision-making support system, and procedure-tracking system. For the severe accident, the severe accident management guideline (SAMG) which is developed by Westinghouse is reviewed; the characteristics, structure, and logical flow of SAMG are studied. In addition, the critical parameters for severe accident, which are the basis for operators decision-making in severe accident management and are supplied to the operators and the technical support center, are reviewed, too.

Review of current status for designing severe accident management support system

International Nuclear Information System (INIS)

Jeong, Kwang Sub

2000-05-01

The development of operator support system (OSS) is ongoing in many other countries due to the complexity both in design and in operation for nuclear power plant. The computerized operator support system includes monitoring of some critical parameters, early detection of plant transient, monitoring of component status, plant maintenance, and safety parameter display, and the operator support system for these areas are developed and are being used in some plants. Up to now, the most operator support system covers the normal operation, abnormal operation, and emergency operation. Recently, however, the operator support system for severe accident is to be developed in some countries. The study for the phenomena of severe accident is not performed sufficiently, but, based on the result up to now, the operator support system even for severe accident will be developed in this study. To do this, at first, the current status of the operator support system for normal/abnormal/emergency operation is reviewed, and the positive aspects and negative aspects of systems are analyzed by their characteristics. And also, the major items that should be considered in designing the severe accident operator support system are derived from the review. With the survey of domestic and foreign operator support systems, they are reviewed in terms of the safety parameter display system, decision-making support system, and procedure-tracking system. For the severe accident, the severe accident management guideline (SAMG) which is developed by Westinghouse is reviewed; the characteristics, structure, and logical flow of SAMG are studied. In addition, the critical parameters for severe accident, which are the basis for operators decision-making in severe accident management and are supplied to the operators and the technical support center, are reviewed, too

2010 Criticality Accident Alarm System Benchmark Experiments At The CEA Valduc SILENE Facility

International Nuclear Information System (INIS)

Miller, Thomas Martin; Dunn, Michael E.; Wagner, John C.; McMahan, Kimberly L.; Authier, Nicolas; Jacquet, Xavier; Rousseau, Guillaume; Wolff, Herve; Piot, Jerome; Savanier, Laurence; Baclet, Nathalie; Lee, Yi-kang; Masse, Veronique; Trama, Jean-Christophe; Gagnier, Emmanuel; Naury, Sylvie; Lenain, Richard; Hunter, Richard; Kim, Soon; Dulik, George Michael; Reynolds, Kevin H.

2011-01-01

Several experiments were performed at the CEA Valduc SILENE reactor facility, which are intended to be published as evaluated benchmark experiments in the ICSBEP Handbook. These evaluated benchmarks will be useful for the verification and validation of radiation transport codes and evaluated nuclear data, particularly those that are used in the analysis of CAASs. During these experiments SILENE was operated in pulsed mode in order to be representative of a criticality accident, which is rare among shielding benchmarks. Measurements of the neutron flux were made with neutron activation foils and measurements of photon doses were made with TLDs. Also unique to these experiments was the presence of several detectors used in actual CAASs, which allowed for the observation of their behavior during an actual critical pulse. This paper presents the preliminary measurement data currently available from these experiments. Also presented are comparisons of preliminary computational results with Scale and TRIPOLI-4 to the preliminary measurement data.

Critical activities of α- and β-emitters in the environment

International Nuclear Information System (INIS)

Kanapickas, A.; Raupeliene, V.

2003-01-01

Environmental analysis of α-emitting radionuclides, such as 137 Cs, is relatively easily carried out, whereas the analysis of the β-emitters 90 Sr, 14 C or even 3 H and the α-emitting isotopes, such as Pu or Am is more complicated. Many of the currently used methods are well suitable for investigations of the environmental behavior of different radionuclides or in analyses of a radioactive fallout. However, the sample pretreatment and a radiochemical separation procedure is generally time-consuming and labor intensive. There is a lack of simple and rapid radioanalytic methods suitable in urgent situations when large amounts of samples have to be processed, such as shortly after a nuclear accident. On the other hand, the detection limits shortly after an accident do not necessarily have to be very low, but have to be clarified if any actions have to be taken. Increased detection limits could allow developing more simple and rapid methods. The required detection limits can be derived from the critical activity concentrations in different environmental materials that would require actions to be taken. However, there are lack of information for critical limits for α- and β-emitters, particularly, 90 Sr, Pu and Am, applicable to the cafe of a nuclear accident. In this work the critical activity concentrations in soil and pasture vegetation that would be required to exceed the action levels for foodstuffs is estimated. Since the action levels recommended by the IAEA are higher than those stated in Lithuanian Hygiene standard HN 54-1998 the latter values are taken as a guide in this study. The results show that if the aim of the analysis is to determine whether or not the action levels will be exceeded the common detection limits for the environmental analysis of α- and β-emitters may be increased at least by two orders of magnitude. In addition to activity concentrations, the critical deposition densities on soil and grazing areas are estimated. Critical limits

NARCISS critical stand experiments for studying the nuclear safety in accident water immersion of highly enriched uranium dioxide fuel elements

International Nuclear Information System (INIS)

Ponomarev-Stepnoj, N.N.; Glushkov, E.S.; Bubelev, V.G.

2005-01-01

A brief description of the Topaz-2 SNPS designed under scientific supervision of RRC KI in Russia, and of the NARCISS critical facility, is given. At the NARCISS critical facility, neutronic peculiarities and nuclear safety issues of the Topaz-2 system reactor were studied experimentally. This work is devoted to a detailed description of experiments on investigation of criticality safety in accident water immersion og highly enriched uranium dioxide fuel elements, performed at the NARCISS facility. The experiments were carried out at water-moderated critical assemblies with varying height, number, and spacing of fuel elements. The results obtained in the critical experiments, computational models of the investigated critical configurations, and comparison of the computational and experimental results are given [ru

Jerky driving--An indicator of accident proneness?

Science.gov (United States)

Bagdadi, Omar; Várhelyi, András

2011-07-01

This study uses continuously logged driving data from 166 private cars to derive the level of jerks caused by the drivers during everyday driving. The number of critical jerks found in the data is analysed and compared with the self-reported accident involvement of the drivers. The results show that the expected number of accidents for a driver increases with the number of critical jerks caused by the driver. Jerk analyses make it possible to identify safety critical driving behaviour or "accident prone" drivers. They also facilitate the development of safety measures such as active safety systems or advanced driver assistance systems, ADAS, which could be adapted for specific groups of drivers or specific risky driving behaviour. Copyright © 2011 Elsevier Ltd. All rights reserved.

Design criteria and principles for criticality detection and alarm systems

International Nuclear Information System (INIS)

Delafield, H.J.; Clifton, J.J.

1984-10-01

The report gives design principles and criteria for criticality detection and alarm systems based on earlier work and revised in the light of more recent experience. In particular, account is taken of the developments which have taken place in the field of radiation detection and in the understanding of the different types of criticality excursion. General guidance is given on the principles to apply in deciding upon the need for a criticality system. The characteristics of a criticality incident are described in terms of the minimum incident of concern, and the radiation field. Criteria for the threshold of detection of a criticality incident are then derived and the methods of detection considered. The selection and siting of criticality detectors is discussed, and design principles are given for alarm systems. Finally, testing and post-alarm procedures are outlined, followed by a summary of the principal recommendations. The supporting Appendices include a discussion of reliability and a summary of radiation detector characteristics. (author)

Rapid evaluation of the neutron dose following a criticality accident by measurement of {sup 24}Na activity; Evaluation rapide de la dose de neutrons a la suite d'un accident de criticite par mesure de l'activite de {sup 24}Na

Energy Technology Data Exchange (ETDEWEB)

Estournel, R [Centre de Production de Plutonium de Marcoule, Service de Protection contre les Rayonnements, 30 (France); Henry, Ph [Centre de Production de Plutonium de Marcoule, Section Medicale et Sociale, 30 (France); Beau, P; Ergas, A [Commissariat a l' Energie Atomique, Service d' Hygiene Atomique, Dept. de la Protection Sanitaire, Chusclan, (France)

1966-07-01

By external measurement of the gamma activity of {sup 24}Na induced in the human organs by a neutron flux during a criticality accident, it is possible to evaluate the personal dose received. Detectors designed for everyday use in health physics can be applied to these measurements, and this is described in the first part of the work. The response of a certain number of induced-activity detectors is presented. The induced activity-dose relationship is studied theoretically in the second part taking into account the neutron spectrum to which the individual has been subjected. The characteristic spectra of three possible types of accident have been used for deducing this relationship. The results obtained show that the method is sufficiently sensitive for present purposes. The accuracy of this method for calculating the dose received during an experiment is discussed. (authors) [French] La mesure par detection externe de l'activite gamma du sodium 24 induit dans l'organisme humain par un flux de neutrons lors d'un accident de criticite rend possible l'evaluation de la dose recue par un individu irradie. L'utilisation de detecteurs d'un emploi courant en radioprotection fait l'objet d'une experimentation qui constitue la premiere partie de cette etude. La reponse d'un certain nombre de detecteurs a une activite induite connue est presentee. La relation dose-activite induite, est etudiee, de maniere theorique, dans la seconde partie, correlativement au spectre des neutrons qui ont atteint l'individu irradie. Les spectres caracteristiques de trois types d'accidents possibles ont ete retenus pour l'etablissement de ces relations. Les resultats obtenus montrent que la methode satisfait avec une sensibilite suffisante au but recherche. La precision avec laquelle on peut ainsi calculer la dose recue au cours d'un accident de criticite est discutee. (auteurs)

Biological dosimetry following exposure to neutrons in a criticality accident

Energy Technology Data Exchange (ETDEWEB)

Lindholm, C. (Radiation and Nuclear Safety Authority, STUK (Finland)); Wojcik, A. (Stockholm Univ. (SU), Stockholm (Sweden)); Jaworska, A. (Norwegian Radiation Protection Authority (NRPA) (Norway))

2011-01-15

The aim of the BIONCA project was to implement cytogenetic techniques for biodosimetry purposes in the Nordic countries. The previous NKS-funded biodosimetry activities (BIODOS and BIOPEX) concentrated on experiments using gamma-irradiation and on developing the PCC ring assay for biodosimetry. Experiments conducted during the present BIONCA project has broadened the biodosimetry capacity of the Nordic countries to include dose estimation of exposure to neutrons for both PCC ring and dicentric chromosome techniques. In 2009, experiments were conducted for establishing both PCC ring and dicentric dose calibration curves. Neutron irradiation of human whole blood obtained from two volunteers was conducted in the Netherlands at the Petten reactor. Cell cultures and analysis of whole blood exposed to eight doses between 0 and 10 Gy were performed for both techniques. For the dicentric assay, excellent uniformity in dose calibration for data from both SU and STUK was observed. For PCC rings, the SU and STUK curves were not equally congruent, probably due to the less uniform scoring criteria. However, both curves displayed strong linearity throughout the dose range. In 2010, an exercise was conducted to simulate a criticality accident and to test the validity of the established dose calibration curves. For accident simulation, 16 blood samples were irradiated in Norway at the Kjeller reactor and analysed for dose estimation with both assays. The results showed that, despite a different com-position of the radiation beams in Petten and Kjeller, good dose estimates were obtained. The activity has provided good experience on collaboration required in radiation emergency situations where the biodosimetry capacity and resources of one laboratory may be inadequate. In this respect, the project has strengthened the informal network between the Nordic countries: STUK, the Finnish Radiation and Nuclear Safety Authority, NRPA, the Norwegian Radiation Protection Authority and SU

Effects of the criticality accident at Tokai-mura on the public's attitude to nuclear power generation

Energy Technology Data Exchange (ETDEWEB)

Kitada, Atsuko [Institute of Social Research, Institute of Nuclear Safety System Inc., Mihama, Fukui (Japan); Hayashi, Chikio [The Institute of Statistical Mathematics, Tokyo (Japan)

2000-09-01

The objective of our study was to clarify the effects on the public's attitude of nuclear power and the criticality accident that occurred at the JCO plant in Tokai-mura, Ibaraki Prefecture. For this purpose, we conducted an awareness survey in the Kansai and Kanto areas two months after the accident. Analysis was made on the basis of the comparison of the survey results with the data that the Institute of Nuclear Safety System had accumulated through continuous awareness surveys on nuclear power generation (regular surveys) since 1993. The public's reactions were twofold. On one hand, there were emotional reactions about accidents in nuclear facilities and a reduction in the sense of security. On the other hand, there were reactions concerning the image of nuclear power plant workers and demand on electricity utilities for enhanced employee education and training. The latter reactions correspond to the problems pointed out after the JCO accident. Regarding the utilization of nuclear power generation, the opinion that 'the utilization of nuclear power generation is unavoidable' accounts for 60% of those surveyed. With the opinion that 'nuclear power generation should be utilized' added, 70% of those surveyed take an affirmative attitude to nuclear power utilization. This situation has remained about the same since 1998, the year before the JCO accident. Using the quantification method III to analyze a number of questionnaires about nuclear power generation such as the anxiety about it, we determined overall attitude indexes regarding nuclear power to perform a time sequence comparison. The comparison shows that the attitude after the JCO accident tended to be more negative than in 1998. However, no significant difference in the overall indexes is seen between 1993 and 1998. Judging the comparison results on the basis of the time span starting in 1993 allows us to conclude that the JCO accident has not greatly contributed to worsening

Improved set of criticality accident detectors used in the intercomparison experiment in Valduc

International Nuclear Information System (INIS)

Jozefowicz, K.; Golnik, N.

1996-01-01

An improved set of critically accident detectors has been elaborated for the needs of the Inst. of Atomic Energy in Swierk. The sets, which consist of fission track detectors, wide-base silicon diodes and RPL glasses, were tested in the international intercomparison experiment in Valduc, France. Comparison of our results with the reference measurements showed a good agreement (within 25%) for both the neutron and gamma measurements. Additionally, the diode response to neutron kerma was investigated more extensively in the dose range between 2 and 10 Gy, where the dependence of the diode signal versus neutron kerma was not well known. A possibility of the multiple use of the diodes has been proved. (author)

Dose-dependent analysis of acute medical effects of mixed neutron-gamma radiation from selected severe 235U or 239Pu criticality accidents in USSR, United States, and Argentina.

Science.gov (United States)

Barabanova, Tatyana; Wiley, Albert L; Bushmanov, Andrey

2012-04-01

Eight of the most severe cases of acute radiation disease (ARS) known to have occurred in humans (as the result of criticality accidents) had survival times less than 120 h (herein defined as "early death"). These accidents were analyzed and are discussed with respect to the specific accident scenarios and the resulting accident-specific, mixed neutron-gamma radiation clinical dose distributions. This analysis concludes that the cardiovascular system appears to be the most critical organ system failure for causing "early death" following approximate total body, mixed gamma-neutron radiation doses greater than 40-50 Gy. The clinical data also suggest that there was definite chest dose dependence in the resulting survival times for these eight workers, who unfortunately suffered profound radiation injury and unusual clinical effects from such high dose radiation exposures. In addition, "toxemic syndrome" is correlated with the irradiation of large volumes of soft tissues. Doses to the hands or legs greater than 80-100 Gy or radiation lung injury also play significant but secondary roles in causing "early death" in accidents delivering chest doses greater than 50 Gy.

Study of a criticality accident involving fuel rods and water outside a power reactor

International Nuclear Information System (INIS)

Beloeil, L.

2000-01-01

It is possible to imagine highly unlikely but numerous accidental situations where fuel rods come into contact with water under conditions close to atmospheric values. This work is devoted to modelling and simulation of first instants of the power excursion that may result from such configurations. We show that void effect is a preponderant feedback for most severe accidents. The formation of a vapour film around the rods is put forward and confirmed with the help of experimental transients using electrical heating. We propose then a vapour/liquid flow model able to reproduce void fraction evolution. The vapour film is treated as a compressible medium. Conservation balance equations are solved on a moving mesh with a two-dimensional scheme and boundary conditions taking notice of interfacial phenomena and axial escape possibility. Movements of the liquid phase are modelled through a non-stationary integral equation and a dissipative term suited to the particular geometry of this flow. The penetration of energy into the liquid is also calculated. Thus, the coupling of aerodynamic and hydrodynamic modules gives results in excellent agreement with experiments. Next, neutronic phenomena into the fuel pellet, their feedback effects and the distribution of power through the rod are numerically translated. For each developed module, validation tests are provided. Then, it is possible to simulate the first seconds of the whole criticality accident. Even if this calculation tool is only a way of study as a first approach, performed simulations are proving coherent with reported data on recorded accidents. (author)

A methodology for the transfer of probabilities between accident severity categories

International Nuclear Information System (INIS)

Whitlow, J.D.; Neuhauser, K.S.

1993-01-01

This paper will describe a methodology which has been developed to allow accident probabilities associated with one severity category scheme to be transferred to another severity category scheme, permitting some comparisons of different studies at the category level. In this methodology, the severity category schemes to be compared are mapped onto a common set of axes. The axes represent critical accident environments (e.g., impact, thermal, crush, puncture) and indicate the range of accident parameters from zero (no accident) to the most sever credible forces. The choice of critical accident environments for the axes depends on the package being transported and the mode of transportation. The accident probabilities associated with one scheme are then transferred to the other scheme. This transfer of category probabilities is based on the relationships of the critical accident parameters to probability of occurrence. The methodology can be employed to transfer any quantity between category schemes if the appropriate supporting information is available. (J.P.N.)

Nuclear fuel cycle facility accident analysis handbook

International Nuclear Information System (INIS)

Ayer, J.E.; Clark, A.T.; Loysen, P.; Ballinger, M.Y.; Mishima, J.; Owczarski, P.C.; Gregory, W.S.; Nichols, B.D.

1988-05-01

The Accident Analysis Handbook (AAH) covers four generic facilities: fuel manufacturing, fuel reprocessing, waste storage/solidification, and spent fuel storage; and six accident types: fire, explosion, tornado, criticality, spill, and equipment failure. These are the accident types considered to make major contributions to the radiological risk from accidents in nuclear fuel cycle facility operations. The AAH will enable the user to calculate source term releases from accident scenarios manually or by computer. A major feature of the AAH is development of accident sample problems to provide input to source term analysis methods and transport computer codes. Sample problems and illustrative examples for different accident types are included in the AAH

Local governments' roles of the compensation for damage by the Tokai JCO criticality accident

Energy Technology Data Exchange (ETDEWEB)

Tanabe, Tomoyuki [Central Research Inst. of Electric Power Industry, Tokyo (Japan). Socio-Economic Research Center

2003-03-01

The Tokai JCO criticality accident on September 30, 1999 was the first case to which The Law on Compensation for Nuclear Damage was applied. Although the Law on Compensation for Nuclear Damage formulates the outline of the institutional framework for nuclear third party liability together with operator's insurance scheme, details of actual compensation procedure are not specified. By this reason, the compensation procedure in the Tokai accident had been executed without a concrete legal specification and a precedent. In spite of this situation, the compensation procedure with the accident led to an unexpectedly successful result. We observe the several reasons why the compensation procedure was implemented successfully despite the lack of concrete legal specification and a precedent. One of the reasons is that the local governments, Tokai Village and Ibaraki Prefecture, immediately took the leadership in implementing a temporary regime of compensation procedure without wasting time for waiting national government's directives. Upon practicing this compensation procedure, the local governments implemented the following steps. (1) Initial estimation of the amount and scope of damage. (2) Providing the criteria and heads of damage subject to compensation. (3) Unitary compensation procedure at the local levels. (4) Distribution of emergency payments for the victims. (5) Facilitating compensatory negotiation between the victims and JCO as arbitrator. However, some concerns are also pointed out about the fact that the local government directed the whole procedure without sufficient adjustment with the national government for compensation policy. Among all, in the compensation led by the local governments, it was difficult to guarantee fairness of compensation because victims who are influential on the local government such as industrial associations would have unfairly strong negotiation power in the compensatory negotiation, while the operator being

The sensitivity of calculated doses to critical assumptions for the offsite consequences of nuclear power reactor accidents

International Nuclear Information System (INIS)

Moeller, M.P.; Scherpelz, R.I.; Desrosiers, A.E.

1982-01-01

This work analyzes the sensitivity of calculated doses to critical assumptions for offsite consequences following a PWR-2 accident at a nuclear power reactor. The calculations include three radiation dose pathways: internal dose resulting from inhalation, external doses from exposure to the plume, and external doses from exposure to contaminated ground. The critical parameters are the time period of integration for internal dose commitment and the duration of residence on contaminated ground. The data indicate the calculated offsite whole body dose will vary by as much as 600% depending upon the parameters assumed. When offsite radiation doses determine the size of emergency planning zones, this uncertainty has significant effect upon the resources allocated to emergency preparedness

Socioeconomic consequences of nuclear reactor accidents

International Nuclear Information System (INIS)

Tawil, J.J.; Callaway, J.W.; Coles, B.L.; Cronin, F.J.; Currie, J.W.; Imhoff, K.L.; Lewis, P.M.; Nesse, R.J.; Strenge, D.L.

1984-06-01

This report identifies and characterizes the off-site socioeconomic consequences that would likely result from a severe radiological accident at a nuclear power plant. The types of impacts that are addressed include economic impacts, health impacts, social/psychological impacts and institutional impacts. These impacts are identified for each of several phases of a reactor accident - from the warning phase through the post-resettlement phase. The relative importance of the impact during each accident phase and the degree to which the impact can be predicted are indicated. The report also examines the methods that are currently used for assessing nuclear reactor accidents, including development of accident scenarios and the estimating of socioeconomic accident consequences with various models. Finally, a critical evaluation is made regarding the use of impact analyses in estimating the contribution of socioeconomic consequences to nuclear accident reactor accident risk. 116 references, 7 figures, 15 tables

Residents call for greater openness, accountability and involvement: Lessons learned from the JCO criticality accident

International Nuclear Information System (INIS)

Taniguchi, Taketoshi; Tsuchiya, Tomoko; Kosugi, Motoko

2000-01-01

This paper discusses the JCO (Japan Nuclear Fuel Conversion Co.) criticality accident from social viewpoints based on the detailed examination of the survey data and experience of participation into Tokai village office's surveys. We focus the mechanisms of amplifying anxieties of the local residents and clarify the key factors affected in the social amplification process. And we discuss the importance of communicating and deliberating among the lay people, public officials and professionals about health, safety and environmental risks associated with nuclear energy, referring to the public opinions about what kinds of information and actions are needed. (J.P.N.)

Study of source term evaluation from fuel solution under simulated nuclear criticality accident in TRACY

International Nuclear Information System (INIS)

Abe, Hitoshi; Tashiro, Shinsuke; Nagai, Hitoshi; Koike, Tadao; Okagawa, Seigo; Murata, Mikio

1999-01-01

In a accident at the dissolver in a reprocessing plant, various fission products and radiolysis gases will be produced in the fuel solution and volatile radioactive nuclides and radiolysis gases and nitrogen oxide will be released into vent-gas spontaneously. Moreover other on-volatile nuclide will be releases as radioactive aerosol (mist) with bursting bubbles at surface of the solution. Therefore quantitative estimation of release and transport behavior of the radioactive material from solution as source term is very important. TRACY is a transient criticality experimental facility for studying the transient criticality characteristics of low enriched uranium. In this paper, experiment methods and results about the release behavior of the hydrogen, radioactive aerosol and iodine species from the fuel solutions are reported. As the results of the experiments, release patterns of H 2 , 140 Ba and 131 I could be grasped. Concentrations of H 2 in the vent-gas and 140 Ba in the gas phase in the core tank attained to the peak just after the transient criticality and decreased exponentially with time. On the other hand, concentrations of 131 I in the gas phase of the tank began to increase with a time lag of several minutes from the transient criticality and attained approximately constant values. (J.P.N.)

Detecting quantum critical points using bipartite fluctuations.

Science.gov (United States)

Rachel, Stephan; Laflorencie, Nicolas; Song, H Francis; Le Hur, Karyn

2012-03-16

We show that the concept of bipartite fluctuations F provides a very efficient tool to detect quantum phase transitions in strongly correlated systems. Using state-of-the-art numerical techniques complemented with analytical arguments, we investigate paradigmatic examples for both quantum spins and bosons. As compared to the von Neumann entanglement entropy, we observe that F allows us to find quantum critical points with much better accuracy in one dimension. We further demonstrate that F can be successfully applied to the detection of quantum criticality in higher dimensions with no prior knowledge of the universality class of the transition. Promising approaches to experimentally access fluctuations are discussed for quantum antiferromagnets and cold gases.

Results of Questionnaire for the member of JHPS concerning the criticality accident at Tokai

International Nuclear Information System (INIS)

2000-01-01

During the investigation of the criticality accident at Tokai occurring on Sep. 30, 1999, the project team in Japan Health Physics Society (JHPS) carried out a questionnaire for the member on the accident and this paper summarized its results. The effective answer was obtained in 36% of members. Major questions (and frequent answers) were: media of information obtained (internet 33%, TV and radio 22%, and newspaper 19%); concerning actions done by Japanese and local governments, the recommendation on Sep. 30 at 15:00 of evacuation for people living in the area within the radius of 350 m (necessary 92%), timing of its release on Oct. 2 at 18:30 (appropriate 41% and too late 36%) and its information to the people (more information needed 60%) and the recommendation on Sep. 30 at 22:30 of in-door refuge within 10 km radius (unnecessary 43% and necessary 41%), timing of its release on Oct. 1 at 16:40 (too late 49%) and its information to the people (more information needed 63%); and safety declaration for food etc. on Oct. 2 at 18:30 (necessary 92%). Based on above results and free description on the questionnaire, JHPS considered the necessity of described systems of JHPS for emergency.(K.H.)

Visualization of Traffic Accidents

Science.gov (United States)

Wang, Jie; Shen, Yuzhong; Khattak, Asad

2010-01-01

Traffic accidents have tremendous impact on society. Annually approximately 6.4 million vehicle accidents are reported by police in the US and nearly half of them result in catastrophic injuries. Visualizations of traffic accidents using geographic information systems (GIS) greatly facilitate handling and analysis of traffic accidents in many aspects. Environmental Systems Research Institute (ESRI), Inc. is the world leader in GIS research and development. ArcGIS, a software package developed by ESRI, has the capabilities to display events associated with a road network, such as accident locations, and pavement quality. But when event locations related to a road network are processed, the existing algorithm used by ArcGIS does not utilize all the information related to the routes of the road network and produces erroneous visualization results of event locations. This software bug causes serious problems for applications in which accurate location information is critical for emergency responses, such as traffic accidents. This paper aims to address this problem and proposes an improved method that utilizes all relevant information of traffic accidents, namely, route number, direction, and mile post, and extracts correct event locations for accurate traffic accident visualization and analysis. The proposed method generates a new shape file for traffic accidents and displays them on top of the existing road network in ArcGIS. Visualization of traffic accidents along Hampton Roads Bridge Tunnel is included to demonstrate the effectiveness of the proposed method.

Analysis of accidents at the LPR (Radiochemical Processes Laboratory)

International Nuclear Information System (INIS)

Kaufmann, F.; Boutet, L.I.

1987-01-01

Accidents are defined as not planned events that may result in the emission of significative quantities of radioactive materials to the environment. The pilot plant has been specifically designed to prevent this type of accidents but there still exists the possibility that one or more accidents can be produced during the plant life. In a first phase, the emission of radionuclides to the environment were evaluated for 13 credible accidents. In a second phase, by means of the calculation program SEDA, specially adapted to this purpose, the critical doses of critical group were calculated for each accident. Due to the small capacity of the pilot plant and the long cooling period of treated fuel, it is concluded that the radiological consequences for the external environment are of very small magnitude. In this way, without need of developing complex fault- or event-trees, it is shown that any of the accidents falls into the non acceptable zone of Farmer diagram. (Author)

The design of a new criticality incident detection and alarm system

International Nuclear Information System (INIS)

Nobes, T.S.

1999-01-01

This paper presents a general review of criticality and its detection. After a brief description of what a criticality incident involves, an outline is given of detection methods and warning systems. (author)

Tchernobyl: a severe accident and its image

International Nuclear Information System (INIS)

Strazzulla, J.

1996-01-01

This paper gives a strong criticism about the false informations that were disseminated by the mass media immediately after the Tchernobyl accident. This accident is taken as an example to illustrate a common attitude in journalistic comments of geopolitical events. (J.S.). 1 photo

Radiation Exposure and Thyroid Cancer Risk After the Fukushima Nuclear Power Plant Accident in Comparison with the Chernobyl Accident

International Nuclear Information System (INIS)

Yamashita, S.; Takamura, N.; Ohtsuru, A.; Suzuki, S.

2016-01-01

The actual implementation of the epidemiological study on human health risk from low dose and low-dose rate radiation exposure and the comprehensive long-term radiation health effects survey are important especially after radiological and nuclear accidents because of public fear and concern about the long-term health effects of low-dose radiation exposure have increased considerably. Since the Great East Japan earthquake and the Fukushima Daiichi Nuclear Power Plant accident in Japan, Fukushima Prefecture has started the Fukushima Health Management Survey Project for the purpose of long-term health care administration and medical early diagnosis/treatment for the prefectural residents. Especially on a basis of the lessons learned from the Chernobyl accident, both thyroid examination and mental health care are critically important irrespective of the level of radiation exposure. There are considerable differences between Chernobyl and Fukushima regarding radiation dose to the public, and it is very difficult to estimate retrospectively internal exposure dose from the short-lived radioactive iodines. Therefore, the necessity of thyroid ultrasound examination in Fukushima and the intermediate results of this survey targeting children will be reviewed and discussed in order to avoid any misunderstanding or misinterpretation of the high detection rate of childhood thyroid cancer. (authors)

Safety and Health Standard 110: Incident/accident reporting and investigation

Energy Technology Data Exchange (ETDEWEB)

Sones, K. [West Kootenay Power, BC (Canada)

1999-10-01

Incident/accident reporting requirements in effect at West Kootenay Power are discussed. Details provided include definitions of low risk, high risk, and critical events, the incidents to be reported, the nature of the reports, the timelines, the investigation to be undertaken for each type of incident/accident, counselling services available to employees involved in serious incidents, and the procedures to be followed in accidents involving serious injury to non-employees. The emphasis is on the `critical five` high risk events and the procedures relating to them.

Criticality Calculations for a Typical Nuclear Fuel Fabrication Plant with Low Enriched Uranium

International Nuclear Information System (INIS)

Elsayed, Hade; Nagy, Mohamed; Agamy, Said; Shaat, Mohmaed

2013-01-01

The operations with the fissile materials such as U 235 introduce the risk of a criticality accident that may be lethal to nearby personnel and can lead the facility to shutdown. Therefore, the prevention of a nuclear criticality accident should play a major role in the design of a nuclear facility. The objectives of criticality safety are to prevent a self-sustained nuclear chain reaction and to minimize the consequences. Sixty criticality accidents were occurred in the world. These are accidents divided into two categories, 22 accidents occurred in process facilities and 38 accidents occurred during critical experiments or operations with research reactor. About 21 criticality accidents including Japan Nuclear Fuel Conversion Co. (JCO) accident took place with fuel solution or slurry and only one accident occurred with metal fuel. In this study the nuclear criticality calculations have been performed for a typical nuclear fuel fabrication plant producing nuclear fuel elements for nuclear research reactors with low enriched uranium up to 20%. The calculations were performed for both normal and abnormal operation conditions. The effective multiplication factor (k eff ) during the nuclear fuel fabrication process (Uranium hexafluoride - Ammonium Diuranate conversion process) was determined. Several accident scenarios were postulated and the criticalities of these accidents were evaluated. The computer code MCNP-4B which based on Monte Carlo method was used to calculate neutron multiplication factor. The criticality calculations Monte Carlo method was used to calculate neutron multiplication factor. The criticality calculations were performed for the cases of, change of moderator to fuel ratio, solution density and concentration of the solute in order to prevent or mitigate criticality accidents during the nuclear fuel fabrication process. The calculation results are analyzed and discussed

Causes of Accidents Near Accelerators and Radiation Protection Arrangements; Causes d'accidents aupres des accelerateurs et dispositions de radioprotection

Energy Technology Data Exchange (ETDEWEB)

Joffre, H; Vialettes, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-07-01

The authors present, first, some typical accidents mentioned in bibliography or happened in CEA Research Centers. The accidents are analysed to precise the main cause and get some experience. Then the authors study the interest of a centralized control for security, detection and signalling devices used near every important accelerator. (author) [French] Les auteurs presentent, tout d'abord, quelques accidents typiques rapportes dans la bibliographie ou survenus dans les Centres de Recherches du CEA. Ces accidents sont analyses pour en preciser la cause principale et en degager les enseignements. Enfin les auteurs etudient l'interet d'un controle centralise des dispositifs de securite, de detection et de signalisation mis en oeuvre aupres de tout accelerateur important. (auteur)

HANARO thermal hydraulic accident analysis

Energy Technology Data Exchange (ETDEWEB)

Park, Chul; Kim, Heon Il; Lee, Bo Yook; Lee, Sang Yong [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1996-06-01

For the safety assessment of HANARO, accident analyses for the anticipated operational transients, accident scenarios and limiting accident scenarios were conducted. To do this, the commercial nuclear reactor system code. RELAP5/MOD2 was modified to RELAP5/KMRR; the thermal hydraulic correlations and the heat exchanger model was changed to incorporate HANARO characteristics. This report summarizes the RELAP/KMRR calculation results and the subchannel analyses results based on the RELAP/KMRR results. During the calculation, major concern was placed on the integrity of the fuel. For all the scenarios, the important accident analysis parameters, i.e., fuel centerline temperatures and the minimum critical heat flux ratio(MCHFR), satisfied safe design limits. It was verified, therefore, that the HANARO was safely designed. 21 tabs., 89 figs., 39 refs. (Author) .new.

Evaluation of Neutron Response of Criticality Accident Alarm System Detector to Quasi-Monoenergetic 24 keV Neutrons

Science.gov (United States)

Tsujimura, Norio; Yoshida, Tadayoshi; Yashima, Hiroshi

The criticality accident alarm system (CAAS), which was recently developed and installed at the Japan Atomic Energy Agency's Tokai Reprocessing Plant, consists of a plastic scintillator combined with a cadmium-lined polyethylene moderator and thereby responds to both neutrons and gamma rays. To evaluate the neutron absorbed dose rate response of the CAAS detector, a 24 keV quasi-monoenergetic neutron irradiation experiment was performed at the B-1 facility of the Kyoto University Research Reactor. The detector's evaluated neutron response was confirmed to agree reasonably well with prior computer-predicted responses.

Evaluation of neutron response of criticality accident alarm system detector to quasi-monoenergetic 24 keV neutrons

International Nuclear Information System (INIS)

Tsujimura, Norio; Yoshida, Tadayoshi; Yashima, Hiroshi

2016-01-01

The criticality accident alarm system (CAAS), which was recently developed and installed at the Japan Atomic Energy Agency's Tokai Reprocessing Plant, consists of a plastic scintillator combined with a cadmium-lined polyethylene moderator and thereby responds to both neutrons and gamma rays. To evaluate the neutron absorbed dose rate response of the CAAS detector, a 24 keV quasi-monoenergetic neutron irradiation experiment was performed at the B-1 facility of the Kyoto University Research Reactor. The detector's evaluated neutron response was confirmed to agree reasonably well with prior computer-predicted responses. (author)

The classification of cases related to Tokai-mura criticality accident. Mental care after radiation exposure

International Nuclear Information System (INIS)

Minoshita, Seiko; Satoh, Shinji

2012-01-01

Cases classified into each pattern, which the authors have met so far after the criticality accident JCO was introduced. Case is introduced, based on multiple cases actually met in medical institutions, has been created as a model case. When the cases that were considered related to the criticality accident in Tokai-mura was summarized, the cases could be classified by the time consultation. Therefore the cases were discussed along the time, also discussed about the time. From the first year to the second year, the most cases seen were the cases with high anxiety. Then, there were many cases which symptoms were worsened by the impact received through the residents meeting. Among the patients who received counseling from half a year to three years after the incident, the onset of mental illness, and the aggravation of the mental disease increased, too. After two or three years of the incident, there were a lot of consultation with women who were pregnant or had infants then. Four years later, men gradually came to have consultation at hospitals. In addition, the consultation of alcohol from problems of a family member has increased. In the first year, there were many patients that a symptom turned worse since they were shocked by the booing of the residents meeting. On the other hand, the patients that a symptom turned worse because of the prolonged issue increased four years later. Four or five years, after the incident the cases of because of bankruptcy or dismissal, life been deteriorated economically were increased, and some cases were led to the discrete of family in a chain reaction. Approximately 10 years later, due to the increase of the aging population, the amount of patient who were frightened because they got cancer increased since they lost the people around them as a result of cancer. (author)

Control of criticality; Kawalan kegentingan

Energy Technology Data Exchange (ETDEWEB)

NONE

1988-12-31

The chapter briefly discussed the following subjects: basic and the principle of criticality, natural uranium, neutron utilization, criticality data for systems, criticality accidents, criticality control i.e. mass, volume and geometry control .

The TMI-2 accident

International Nuclear Information System (INIS)

Loureiro, L.A.

1986-01-01

A critical study about the technical and man-related facts in order to establish what is considered the worst commercial nuclear power accident until 1986. Radiological consequences and stress to the public are considered in contrast to antinuclear groups. This descriptive and technical study has the purpose to document written and oral opinions obtained abroad and then explain to the public in an easy language terminology. Preliminary study describing safety related systems fails and the accident itself with minute to minute description, conduct to the consequences and then, to learned lessons

Accidents - Chernobyl accident; Accidents - accident de Tchernobyl

Energy Technology Data Exchange (ETDEWEB)

NONE

2004-07-01

This file is devoted to the Chernobyl accident. It is divided in four parts. The first part concerns the accident itself and its technical management. The second part is relative to the radiation doses and the different contaminations. The third part reports the sanitary effects, the determinists ones and the stochastic ones. The fourth and last part relates the consequences for the other European countries with the case of France. Through the different parts a point is tackled with the measures taken after the accident by the other countries to manage an accident, the cooperation between the different countries and the groups of research and studies about the reactors safety, and also with the international medical cooperation, specially for the children, everything in relation with the Chernobyl accident. (N.C.)

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)

Use of nonstatistical techniques for pattern recognition to detect risk groups among liquidators of the Chernobyl NPP accident aftereffects

International Nuclear Information System (INIS)

Blinov, N.N.; Guslistyj, V.P.; Misyurev, A.V.; Novitskaya, N.N.; Snigireva, G.P.

1993-01-01

Attempt of using of the nonstatistical techniques for pattern recognition to detect the risk groups among liquidators of the Chernobyl NPP accident aftereffects was described. 14 hematologic, biochemical and biophysical blood serum parameters of the group of liquidators of the Chernobyl NPP accident impact as well as the group of donors free of any radiation dose (controlled group) were taken as the diagnostic parameters. Modification of the nonstatistical techniques for pattern recognition based on the assessment calculations were used. The patients were divided into risk group at the truth ∼ 80%

CRITICAL INFORMATION INFRASTRUCTURE SECURITY - NETWORK INTRUSION DETECTION SYSTEMS

Directory of Open Access Journals (Sweden)

Cristea DUMITRU

2011-12-01

Full Text Available Critical Information Infrastructure security will always be difficult to ensure, just because of the features that make it irreplaceable tor other critical infrastructures normal operation. It is decentralized, interconnected interdependent, controlled by multiple actors (mainly private and incorporating diverse types of technologies. It is almost axiomatic that the disruption of the Critical Information Infrastructure affects systems located much farther away, and the cyber problems have direct consequences on the real world. Indeed the Internet can be used as a multiplier in order to amplify the effects of an attack on some critical infrastructures. Security challenges increase with the technological progress. One of the last lines of defense which comes to complete the overall security scheme of the Critical Information Infrastructure is represented by the Network Intrusion Detection Systems.

Criticality safety and facility design considerations

International Nuclear Information System (INIS)

Waltz, W.R.

1991-06-01

Operations with fissile material introduce the risk of a criticality accident that may be lethal to nearby personnel. In addition, concerns over criticality safety can result in substantial delays and shutdown of facility operations. For these reasons, it is clear that the prevention of a nuclear criticality accident should play a major role in the design of a nuclear facility. The emphasis of this report will be placed on engineering design considerations in the prevention of criticality. The discussion will not include other important aspects, such as the physics of calculating limits nor criticality alarm systems

Radiation Exposure and Thyroid Cancer Risk After the Fukushima Nuclear Power Plant Accident in Comparison with the Chernobyl Accident.

Science.gov (United States)

Yamashita, S; Takamura, N; Ohtsuru, A; Suzuki, S

2016-09-01

The actual implementation of the epidemiological study on human health risk from low dose and low-dose rate radiation exposure and the comprehensive long-term radiation health effects survey are important especially after radiological and nuclear accidents because of public fear and concern about the long-term health effects of low-dose radiation exposure have increased considerably. Since the Great East Japan earthquake and the Fukushima Daiichi Nuclear Power Plant accident in Japan, Fukushima Prefecture has started the Fukushima Health Management Survey Project for the purpose of long-term health care administration and medical early diagnosis/treatment for the prefectural residents. Especially on a basis of the lessons learned from the Chernobyl accident, both thyroid examination and mental health care are critically important irrespective of the level of radiation exposure. There are considerable differences between Chernobyl and Fukushima regarding radiation dose to the public, and it is very difficult to estimate retrospectively internal exposure dose from the short-lived radioactive iodines. Therefore, the necessity of thyroid ultrasound examination in Fukushima and the intermediate results of this survey targeting children will be reviewed and discussed in order to avoid any misunderstanding or misinterpretation of the high detection rate of childhood thyroid cancer. © World Health Organisation 2016. All rights reserved. The World Health Organization has granted Oxford University Press permission for the reproduction of this article.

A Study on the Operation Strategy for Combined Accident including TLOFW accident

International Nuclear Information System (INIS)

Kim, Bo Gyung; Kang, Gook Young; Yoon, Ho Joon

2014-01-01

It is difficult for operators to recognize the necessity of a feed-and-bleed (F-B) operation when the loss of coolant accident and failure of secondary side occur. An F-B operation directly cools down the reactor coolant system (RCS) using the primary cooling system when residual heat removal by the secondary cooling system is not available. The plant is not always necessary the F-B operation when the secondary side is failed. It is not necessary to initiate an F-B operation in the case of a medium or large break because these cases correspond to low RCS pressure sequences when the secondary side is failed. If the break size is too small to sufficiently decrease the RCS pressure, the F-B operation is necessary. Therefore, in the case of a combined accident including a secondary cooling system failure, the provision of clear information will play a critical role in the operators' decision to initiate an F-B operation. This study focuses on the how we establish the operation strategy for combined accident including the failure of secondary side in consideration of plant and operating conditions. Previous studies have usually focused on accidents involving a TLOFW accident. The plant conditions to make the operators confused seriously are usually the combined accident because the ORP only focuses on a single accident and FRP is less familiar with operators. The relationship between CET and PCT under various plant conditions is important to decide the limitation of initiating the F-B operation to prevent core damage

Radioactive fallout from the Chernobyl nuclear reactor accident

International Nuclear Information System (INIS)

Beiriger, J.M.; Failor, R.A.; Marsh, K.V.; Shaw, G.E.

1987-08-01

This report describes the detection of fallout in the United States from the Chernobyl nuclear reactor accident. As part of its environmental surveillance program, Lawrence Livermore National Laboratory maintained detectors for gamma-emitting radionuclides. Following the reactor accident, additional air filters were set out. Several uncommon isotopes were detected at the time the plume passed into the US

Trial evaluation on criticality safety of the fuel assemblies at falling accident as spent fuel transport and storage cask

International Nuclear Information System (INIS)

Tadano, Tomoaki

2016-01-01

The authors conducted critical safety assessment on the supposed event at the time of a fall accident of cask, and examined the influence on criticality safety. If the spacer of fuel assembly is sound, it is assumed that the pitch of fuel rod interval changes, and if the spacer is broken, it is assumed that the fuel rod is unevenly distributed in the basket. For the critical calculation of fuel assembly basket system, they performed it using a calculation code. For both of the single cell and assembly, calculation results showed an increase in the effective multiplication factor of reactivity of 2-3%. When this reactivity is applied to the criticality analysis result of PWR fuel assembly, the value approaches to the limit 0.95 of the neutron effective multiplication factor keff. However, the keff when new fuel is loaded is sufficiently lower than 0.93. Therefore, it is unlikely that the criticality analysis result approaches to 0.95 at all burnups, and the possibility to become criticality is very low in actual spent fuel transport. When considering the reactivity of this research, it is possible that the design condition for the assumption of novel fuel loading becomes severer. Furthermore, criticality analysis under non-uniform pitch will become necessary, and criticality safety analysis for BWR fuel with heterogeneous enrichment degree and burnup degree will become also necessary. (A.O.)

Criticality accident in uranium fuel processing plant. Efficacy of insurance and third party inspection system. Capability margins of insurance, in view of bitter experience at JCO

Energy Technology Data Exchange (ETDEWEB)

Izumi, Taiichiro [Songaihokenryoritsusanteikai (Japan)

2000-08-01

Among persons relating to safety engineering, most of them point out merit and demerit of safety theory in Japan since a long term before. Under national policy aiming at growth and expansion due to a policy under leading of government after war, running for about 50 years remained some strains containing a number of contradictions and absurdities in various fields. Here was described mainly on how to be done safety accident protection and inspection on a base of happenings incidentally seen at a chance of the criticality accident. Therefore, here were also established some viewpoints such as transferable risk, limit from insurance feature, genealogy of insurance, under-writing, and risk management, to mention effectiveness of the third party inspection with closed relationship with accident insurance. (G.K.)

Criticality accident in uranium fuel processing plant. Efficacy of insurance and third party inspection system. Capability margins of insurance, in view of bitter experience at JCO

International Nuclear Information System (INIS)

Izumi, Taiichiro

2000-01-01

Among persons relating to safety engineering, most of them point out merit and demerit of safety theory in Japan since a long term before. Under national policy aiming at growth and expansion due to a policy under leading of government after war, running for about 50 years remained some strains containing a number of contradictions and absurdities in various fields. Here was described mainly on how to be done safety accident protection and inspection on a base of happenings incidentally seen at a chance of the criticality accident. Therefore, here were also established some viewpoints such as transferable risk, limit from insurance feature, genealogy of insurance, under-writing, and risk management, to mention effectiveness of the third party inspection with closed relationship with accident insurance. (G.K.)

Multi-micronucleus cells related with viral diseases, detected in the study of children affected by the Chernobyl accident

International Nuclear Information System (INIS)

Garcia L, O.; Lamadrid, A.I.; Manzano, J.

1996-01-01

Cells with multiple chromosome aberrations have been observed in human peripheral blood lymphocytes. Different explanation have proposed, included hot particle induction in persons related to the Chernobyl accident. The frequency of chromosome aberration and micronuclei were established in 14 Ukrainian children with different hematological disorders. They arrived in Cuba thanks to the program by means of which medical attention is offered to children from areas affected by the Chernobyl accident. At least 500 metaphases and bi-nucleate cells were analyzed in each case. The detection of 4 cells with 7-11 micronuclei in a 14 year old boy with cat scratch disease was the most significant cytogenetical finding. The viral origin of the cat scratch disease has been reported, this suggested a viral etiology of the cells with multiple micronuclei. No rogue cells were detected. Cells with multiple micronuclei or rogue cells were not found in other patients from this group. (authors). 7 refs., 3 tabs

A methodology for the transfer of probabilities between accident severity categories

International Nuclear Information System (INIS)

Whitlow, J.D.; Neuhauser, K.S.

1992-01-01

Evaluation of the radiological risks of accidents involving vehicles transporting radioactive materials requires consideration of both accident probability and consequences. The probability that an accident will occur may be estimated from historical accident data for the given mode of transport. In addition to an overall accident rate, information regarding accident severity and the resulting package environments across the range of all credible accidents is needed to determine the potential for a release of radioactive material from the package or for an increase in direct radiation from the package caused by damage to packaging shielding. This information is usually obtained from a variety of sources such as historical data, experimental data, analyses of accident and package environments, and expert opinion. The consequences of an accident depend on a number of factors including the type, quantity, and physical form of radioactive material being transported; the response of the package to accident environments; the fraction of material released from the package; and the dispersion of any released material. One approach for the classification and treatment of transportation accidents in risk analysis divides the complete range of critical accident environments resulting from all credible accidents into some number of accident-severity categories. The types of accident environments that a package may be subjected to in transportation are often classified into the following five groups: impact, fire, crush, puncture, and immersion. A open-quotes criticalclose quotes accident environment is one of a type that could present a plausible threat to a package. Each severity category represents a portion of all credible accidents, and the total of all severity categories covers the complete range of critical accident environments. This approach is used in the risk assessment codes RADTRAN (Neuhauser and Kanipe 1992) and INTERTRAN (Ericsson and Elert 1983)

Causes of several accidents in gamma radiography testing units

International Nuclear Information System (INIS)

Vykrocil, L.

1979-01-01

Three cases are described of radiation accidents in gamma flaw-detection work-places in the West Bohemian Region. The causes of the accidents stemmed from the unsatisfactory technical condition of the materials testing equipment used and nonobservance of regulations for work with radioactive sourr.es. It is necessary for precluding similar accident to improve preventive care of gamma flaw-detection equipment and to educate personnel who would be considered for coping with the situation when control over the radiation source is lost. (Ha)

[Accident cause masculinity?--Gender-related issues of accident victims between prevention and coping in Kaiserreich and Weimarer Republik].

Science.gov (United States)

Knoll-Jung, Sebastian

2015-01-01

Occupational accidents in industrial workplaces are a specific health problem for man. Therefore it seems adequate to use masculinities as a category of research in this field. For the Kaiserreich and the Weimarer Republik it shows that male workers relating to their danger awareness and behavior, prevention, accident causes and coping strategies are settled in an area of conflict between a hard workplace environment and the family. On the basis of health practices of the accident victims it appears that there are different forms of labor masculinities. They have an important influence on all levels of an occupational accident from the endangerment to the success of the treatment. Through a critical use of the category academic void can be shown and alternative explanatory models can be offered.

Evaluation of the influences of nuclear accident by hedonic approach

International Nuclear Information System (INIS)

Takai, Toru

2005-01-01

The purpose of this sturdy is to examine the influences on residential land prices of criticality accident in Tokai-mura. To clarify the influences, three types of hedonic model are used to estimate land prices around JCO before and after the accident. The result of estimation indicates that land prices decreased according to proximity to JCO after the accident. (author)

A Simple Predictive Method of Critical Flicker Detection for Human Healthy Precaution

Directory of Open Access Journals (Sweden)

Goh Zai Peng

2015-01-01

Full Text Available Interharmonics and flickers have an interrelationship between each other. Based on International Electrotechnical Commission (IEC flicker standard, the critical flicker frequency for a human eye is located at 8.8 Hz. Additionally, eye strains, headaches, and in the worst case seizures may happen due to the critical flicker. Therefore, this paper introduces a worthwhile research gap on the investigation of interrelationship between the amplitudes of the interharmonics and the critical flicker for 50 Hz power system. Consequently, the significant findings obtained in this paper are the amplitudes of two particular interharmonics are able to detect the critical flicker. In this paper, the aforementioned amplitudes are detected by adaptive linear neuron (ADALINE. After that, the critical flicker is detected by substituting the aforesaid amplitudes to the formulas that have been generated in this paper accordingly. Simulation and experimental works are conducted and the accuracy of the proposed algorithm which utilizes ADALINE is similar, as compared to typical Fluke power analyzer. In a nutshell, this simple predictive method for critical flicker detection has strong potential to be applied in any human crowded places (such as offices, shopping complexes, and stadiums for human healthy precaution purpose due to its simplicity.

Strategy generation in accident management support

International Nuclear Information System (INIS)

Sirola, M.

1995-01-01

An increased interest for research in the field of Accident Management can be noted. Several international programmes have been started in order to be able to understand the basic physical and chemical phenomena in accident conditions. A feasibility study has shown that it would be possible to design and develop a computerized support system for plant staff in accident situations. To achieve this goal the Halden Project has initiated a research programme on Computerized Accident Management Support (CAMS project). The aim is to utilize the capabilities of computerized tools to support the plant staff during the various accident stages. The system will include identification of the accident state, assessment of the future development of the accident and planning of accident mitigation strategies. A prototype is developed to support operators and the Technical Support Centre in decision making during serious accident in nuclear power plants. A rule based system has been built to take care of the strategy generation. This system assists plant personnel in planning control proposals and mitigation strategies from normal operation to severe accident conditions. The ideal of a safety objective tree and knowledge from the emergency procedures have been used. Future prediction requires good state identification of the plant status and some knowledge about the history of some critical variables. The information needs to be validated as well. Accurate calculations in simulators and a large database including all important information form the plant will help the strategy planning. (author). 12 refs, 2 figs

Using Pennsylvania's Three Mile Island Accident as a Case Study to Analyze Newspaper Coverage: A Diary of Events and Suggestions for Teaching Strategies.

Science.gov (United States)

Susskind, Jacob L.

1983-01-01

Methods for studying the coverage of the same current news story in several newspapers are outlined. Secondary school students critically examine news reporting, detect false or propagandistic reports, and learn to weigh and judge evidence. An example using the Three Mile Island nuclear accident is provided. (KC)

A critical review of Jan Beyea's report: A study of some of the consequences of hypothetical reactor accidents at Barsebaeck

International Nuclear Information System (INIS)

Gjoerup, H.L.; Hedemann Jensen, P.; Jensen, N.O.; Pejtersen, V.; Lundtang Petersen, E.; Petersen, T.; Thykier-Nielsen, S.; Heikel Vinther, F.

1978-04-01

This report contains a critical review of Jan Beyea's report: A study of some of the consequences of hypothetical reactor accidents at Barsebaeck (Princeton University, January 1978). Unreasonable assumptions concerning dry deposition, plume rise, meteorological considerations, dose-response relationship and probability distributions were found in the report. It is found that the conclusions of the Beyea report are the result of a mathematical exercise rather than the results of a realistic risk evaluation for Barsebaeck. (author)

Personal nuclear accident dosimetry at Sandia National Laboratories

International Nuclear Information System (INIS)

Ward, D.C.; Mohagheghi, A.H.; Burrows, R.

1996-09-01

DOE installations possessing sufficient quantities of fissile material to potentially constitute a critical mass, such that the excessive exposure of personnel to radiation from a nuclear accident is possible, are required to provide nuclear accident dosimetry services. This document describes the personal nuclear accident dosimeter (PNAD) used by SNL and prescribes methodologies to initially screen, and to process PNAD results. In addition, this report describes PNAD dosimetry results obtained during the Nuclear Accident Dosimeter Intercomparison Study (NAD23), held during 12-16 June 1995, at Los Alamos National Laboratories. Biases for reported neutron doses ranged from -6% to +36% with an average bias of +12%

Criticality safety (prospect of study in NUCEF)

International Nuclear Information System (INIS)

Itagaki, Masafumi

1996-01-01

Experimental studies of criticality safety are under way using STACY and TRACY in NUCEF. Collection of fundamental data on criticality in a solution system is undergoing with STACY to confirm that the likelihood of criticality safety in the system constructed on the assumption of apparatuses in a reprocessing plant is enough large. Whereas some experiments simulating criticality accidents in a reprocessing plant using TRACY were designed to investigate the behaviors of fuel solution and radioactive matters in order to clarify whether it is possible to safely shut them in the facility even if a critical accident occurs. Both STACY and TRACY reached the criticality in 1995. Up to now a series of criticality experiments have been done using STACY with a core tank φ60 cm and the first periodical examination is now under way. On the other hand, we have a plan using TRACY to investigate the behaviors of nuclear heat solution at a criticality accident, and the releasing, transfer and deposition of radioactive materials. After reaching the criticality for the first, the performance verification test has been conducted. The full-scale study using TRACY is planned to begin in the second half of 1996. (M.N.)

Development of Human Factor Management Requirements and Human Error Classification for the Prevention of Railway Accident

International Nuclear Information System (INIS)

Kwak, Sang Log; Park, Chan Woo; Shin, Seung Ryoung

2008-08-01

Railway accident analysis results show that accidents cased by human factors are not decreasing, whereas H/W related accidents are steadily decreasing. For the efficient management of human factors, many expertise on design, conditions, safety culture and staffing are required. But current safety management activities on safety critical works are focused on training, due to the limited resource and information. In order to improve railway safety, human factors management requirements for safety critical worker and human error classification is proposed in this report. For this accident analysis, status of safety measure on human factor, safety management system on safety critical worker, current safety planning is analysis

Evaluation of dose equivalent rate distribution in JCO critical accident by radiation transport calculation

CERN Document Server

Sakamoto, Y

2002-01-01

In the prevention of nuclear disaster, there needs the information on the dose equivalent rate distribution inside and outside the site, and energy spectra. The three dimensional radiation transport calculation code is a useful tool for the site specific detailed analysis with the consideration of facility structures. It is important in the prediction of individual doses in the future countermeasure that the reliability of the evaluation methods of dose equivalent rate distribution and energy spectra by using of Monte Carlo radiation transport calculation code, and the factors which influence the dose equivalent rate distribution outside the site are confirmed. The reliability of radiation transport calculation code and the influence factors of dose equivalent rate distribution were examined through the analyses of critical accident at JCO's uranium processing plant occurred on September 30, 1999. The radiation transport calculations including the burn-up calculations were done by using of the structural info...

Strategy-oriented display concept to assist severe accident management

International Nuclear Information System (INIS)

Jeong, Kwangsub; Ha, Jaejoo

2000-01-01

The Critical Function Monitoring System (CFMS) is a typical Safety Parameter Display System (SPDS) to assist the operation of Korean Standard Nuclear Power Plants during normal and emergency operation, and SPDS for severe accident is being developed in Korea. When the existing CFMS is used under a severe accident situation, some problems are expected from: (1) different design basis, i.e. prevention of core melt vs. protection of radiation release to environment, (2) different parameters for decision-making, and (3) different domain and depth of information to restore the plant. To resolve the above problems, a concept, 'Strategy-Oriented Information Display' concept, for displaying information for severe accident management is developed in this paper. Whereas the existing SPDS structure is based on the critical safety function, the developed concept is based on the severe accident management strategy. The display for each strategy includes the plant parameters to check the status of plant and component with the logical or graphical views necessary for executing the strategy. As the application of the proposed concept, KAERI is developing a display system, the prototype severe accident SPDS, Severe Accident Management Display System (SAMDIS), to assist plant personnel for executing Korean Severe Accident Management Guidelines. CFMS is developed for a general display suitable to all situations with various displays. On the contrary, SAMDIS provides all the relevant information on one screen based on the proposed concept. The SAMDIS screen shows more extensive area than CFMS and thus plant personnel can recognize the overall plant status at a glance. This concept is quite effective when used with severe accident management guidelines because of the relatively macroscopic characteristics of a severe accident management strategy. (author)

An updated nuclear criticality slide rule

International Nuclear Information System (INIS)

Hopper, C.M.; Broadhead, B.L.

1998-04-01

This Volume 2 contains the functional version of the updated nuclear criticality slide rule (more accurately, sliding graphs) that is referenced in An Updated Nuclear Criticality Slide Rule: Technical Basis, NUREG/CR-6504, Vol. 1 (ORNL/TM-13322/V1). This functional slide rule provides a readily usable open-quotes in-handclose quotes method for estimating pertinent nuclear criticality accident information from sliding graphs, thereby permitting (1) the rapid estimation of pertinent criticality accident information without laborious or sophisticated calculations in a nuclear criticality emergency situation, (2) the appraisal of potential fission yields and external personnel radiation exposures for facility safety analyses, and (3) a technical basis for emergency preparedness and training programs at nonreactor nuclear facilities. The slide rule permits the estimation of neutron and gamma dose rates and integrated doses based upon estimated fission yields, distance from the fission source, and time-after criticality accidents for five different critical systems. Another sliding graph permits the estimation of critical solution fission yields based upon fissile material concentration, critical vessel geometry, and solution addition rate. Another graph provides neutron and gamma dose-reduction factors for water, steel, and concrete. Graphs from historic documents are provided as references for estimating critical parameters of various fissile material systems. Conversion factors for various English and metric units are provided for quick reference

Realistic minimum accident source terms - Evaluation, application, and risk acceptance

International Nuclear Information System (INIS)

Angelo, P. L.

2009-01-01

The evaluation, application, and risk acceptance for realistic minimum accident source terms can represent a complex and arduous undertaking. This effort poses a very high impact to design, construction cost, operations and maintenance, and integrated safety over the expected facility lifetime. At the 2005 Nuclear Criticality Safety Division (NCSD) Meeting in Knoxville Tenn., two papers were presented mat summarized the Y-12 effort that reduced the number of criticality accident alarm system (CAAS) detectors originally designed for the new Highly Enriched Uranium Materials Facility (HEUMF) from 258 to an eventual as-built number of 60. Part of that effort relied on determining a realistic minimum accident source term specific to the facility. Since that time, the rationale for an alternate minimum accident has been strengthened by an evaluation process that incorporates realism. A recent update to the HEUMF CAAS technical basis highlights the concepts presented here. (authors)

Computerized accident management support system: development for severe accident management

International Nuclear Information System (INIS)

Garcia, V.; Saiz, J.; Gomez, C.

1998-01-01

The activities involved in the international Halden Reactor Project (HRP), sponsored by the OECD, include the development of a Computerized Accident Management Support System (CAMS). The system was initially designed for its operation under normal conditions, operational transients and non severe accidents. Its purpose is to detect the plant status, analyzing the future evolution of the sequence (initially using the APROS simulation code) and the possible recovery and mitigation actions in case of an accident occurs. In order to widen the scope of CAMS to severe accident management issues, the integration of the MAAP code in the system has been proposed, as the contribution of the Spanish Electrical Sector to the project (with the coordination of DTN). To include this new capacity in CAMS is necessary to modify the system structure, including two new modules (Diagnosis and Adjustment). These modules are being developed currently for Pressurized Water Reactors and Boiling Water REactors, by the engineering of UNION FENOSA and IBERDROLA companies (respectively). This motion presents the characteristics of the new structure of the CAMS, as well as the general characteristics of the modules, developed by these companies in the framework of the Halden Reactor Project. (Author)

WWER-440/V-230 Confinement modernization to upgrade the critical safety function 'Containment integrity' in case of severe accident

International Nuclear Information System (INIS)

Sartmadjiev, A.

1999-01-01

In this lecture the WWER-440/V-230 confinement modernization to upgrade the critical safety function 'Containment integrity' in case of severe accident is presented. There are discussed: design limitations of the location system; consequence from these design limitations; a few confinement reconstruction concepts of this type of units worldwide; and purpose of the confinement reconstruction - to improve significantly the original design, ensuring (1) localization for all possible primary breaks and (2) limitation of the radiological consequences for the personnel, the population and the environment below the regulatory requirements

TL detectors for gamma ray dose measurements in criticality accidents

International Nuclear Information System (INIS)

Miljanic, S.; Zorko, B.; Gregori, B.; Knezevic, Z.

2007-01-01

Determination of gamma ray dose in mixed neutron + gamma ray fields is still a demanding task. Dosemeters used for gamma ray dosimetry are usually in some extent sensitive to neutrons and their response variations depend on neutron energy i.e., on neutron spectra. Besides, it is necessary to take into account the energy dependence of dosemeter responses to gamma rays. In this work, several types of thermoluminescent detectors (TLD) placed in different holders used for gamma ray dose determination in the mixed fields were examined. Dosemeters were from three different institutions: Ruder Boskovic Inst. (RBI), Croatia, Jozef Stefan Inst. (JSI), Slovenia and Autoridad Regulatoria Nuclear (ARN), Argentina. All dosemeters were irradiated during the International Intercomparison of Criticality Accident Dosimetry Systems at the SILENE Reactor, Valduc, June 2002. Three accidental scenarios were reproduced and in each irradiation the dosemeters were exposed placed on the front of phantom and 'free in air'. Following types of TLDs were used: 7 LiF (TLD-700), CaF 2 :Mn and Al2 O3 :Mg,Y - all from RBI; CaF 2 :Mn from JSI and 7 LiF (TLD-700) from ARN. Reported doses were compared with the reference values as well as with the values obtained from the results of all participants. The results show satisfactory agreement with other dosimetry systems used in the Intercomparison. The influence of different types of holders and applied corrections of dosemeters' readings are discussed. (authors)

TL detectors for gamma ray dose measurements in criticality accidents.

Science.gov (United States)

Miljanić, Saveta; Zorko, Benjamin; Gregori, Beatriz; Knezević, Zeljka

2007-01-01

Determination of gamma ray dose in mixed neutron+gamma ray fields is still a demanding task. Dosemeters used for gamma ray dosimetry are usually in some extent sensitive to neutrons and their response variations depend on neutron energy i.e., on neutron spectra. Besides, it is necessary to take into account the energy dependence of dosemeter responses to gamma rays. In this work, several types of thermoluminescent detectors (TLD) placed in different holders used for gamma ray dose determination in the mixed fields were examined. Dosemeters were from three different institutions: Ruder Bosković Institute (RBI), Croatia, JoZef Stefan Institute (JSI), Slovenia and Autoridad Regulatoria Nuclear (ARN), Argentina. All dosemeters were irradiated during the International Intercomparison of Criticality Accident Dosimetry Systems at the SILENE Reactor, Valduc, June 2002. Three accidental scenarios were reproduced and in each irradiation the dosemeters were exposed placed on the front of phantom and 'free in air'. Following types of TLDs were used: 7LiF (TLD-700), CaF2:Mn and Al2O3:Mg,Y-all from RBI; CaF2:Mn from JSI and 7LiF (TLD-700) from ARN. Reported doses were compared with the reference values as well as with the values obtained from the results of all participants. The results show satisfactory agreement with other dosimetry systems used in the Intercomparison. The influence of different types of holders and applied corrections of dosemeters' readings are discussed.

Investigation of Qom Rural Area Water Network Accident in 2010 and Minimization Approaches of Accident Frequencies

Directory of Open Access Journals (Sweden)

Hossein Jafari Mansoorian

2016-02-01

Full Text Available Background & Aims of the Study : Accidents in water networks can lead to increase the uncounted water, costs of repair, maintenance, restoration and enter water contaminants to water network. The aim of this study is to survey the accidents of Qom rural water network and choose the right approaches to reduce the number of accidents. Materials & Methods: In this cross-sectional study, four sector of Qom province (Markazi, Dastjerd, Kahak and Qahan, were assessed over a period of 8 months (July – January 2010. This study was conducted through questionnaire of Ministry of Energy. Results: The total number of accidents was 763. The highest number of accidents in the four sectors was related to Markazi sector with 228 accidents. According to the time of the accident, the highest and lowest number of accident was related to September (19.7% and November (6.8%, respectively. According to the location of the accident on network, the highest and lowest number of accident was related to distribution network (64% and connections (17.5% and transmission pipe (18.34%, respectively. According to the type of the accident, the highest and lowest number of accident was related to breaking (47.8% and gasket failure (1.2%, respectively. Considering with the pipes’ material, the highest and lowest number of accident was related to polyethylene pipes (93% and steel and cast iron pipes (0.5%, 0.5%, respectively. Conclusions: Due to the high break rate of Polyethylene pipes, it is recommended to be placed in priority of leak detection and rehabilitation.   .

The Physics of Traffic Accidents

Science.gov (United States)

Knight, Peter

1975-01-01

Shows how physics can be used to analyze and prevent traffic accidents by determining critical speeds on curves, the behavior of motor cycles and stability of articulated vehicles, and the visibility that is needed to make a minor road junction safe. (MLH)

Design features of ACR in severe accident mitigation

International Nuclear Information System (INIS)

Shapiro, H.; Krishnan, V.S.; Santamaura, P.; Lekakh, B.; Blahnik, C.

2007-01-01

failed structure would retain some capability to reduce radioactivity release into the environment. SAMDAs that enhance the capabilities for minimizing the offsite releases (venting) are being actively examined further. State-of-the art hydrogen control of igniters and passive, auto-catalytic recombiners are provided. The ACR design is not prone to core-concrete interactions by virtue of multiple, externally cooled barriers between the fuel and the containment floor as well as due to characteristics of the compartment into which the core materials would eventually penetrate (i.e., a large area for debris spread and multiple means of keeping the debris submerged in water). The instrumentation that provides reliable data to the severe accident management team is critical to successful accident mitigation. The ACR instruments provide the necessary coverage of all critical plant parameters in two locations (main control room and secondary control area). As far as practical, these instruments will be hardened to withstand the severe accident conditions. All critical instruments will be assessed for survivability under severe accident conditions. (authors)

The social background of the JCO accident and the real location of its responsibility

International Nuclear Information System (INIS)

Mitsugashira, Toshiaki

2001-01-01

The background of the occurrence of the JCO criticality accident seems to be in the defect of the safeguard inspection. According to the guideline of the safeguard inspection for uranium processing plants, the countermeasures to the criticality accident are not necessary as far as the plant is designed not to reach the critical condition. The guideline is ruled to be applied to the facility for the processing of uranium whose enrichment is below 5%. This means that the safeguard inspection for the Uranium Conversion Building (UCB) of JCO is the matter to be made according to the basic safeguard guideline that demands the countermeasures to the criticality accident because the 18% enriched uranium was processed in UCB. As for the reprocessing of the nuclear fuel that underwent the criticality, it was done without examining a legal basis fully. (author)

Development of integrated accident management assessment technology

International Nuclear Information System (INIS)

Jung, Won Dea; Ha, Jae Joo; Jin, Young Ho

2002-04-01

This project aims to develop critical technologies for accident management through securing evaluation frameworks and supporting tools, in order to enhance capabilities coping with severe accidents. For the research goal, firstly under the viewpoint of accident prevention, on-line risk monitoring system and the analysis framework for human error have been developed. Secondly, the training/supporting systems including the training simulator and the off-site risk evaluation system have been developed to enhance capabilities coping with severe accidents. Four kinds of research results have been obtained from this project. Firstly, the framework and taxonomy for human error analysis has been developed for accident management. As the second, the supporting system for accident managements has been developed. Using data that are obtained through the evaluation of off-site risk for Younggwang site, the risk database as well as the methodology for optimizing emergency responses has been constructed. As the third, a training support system, SAMAT, has been developed, which can be used as a training simulator for severe accident management. Finally, on-line risk monitoring system, DynaRM, has been developed for Ulchin 3 and 4 unit

The program of international intercomparison of accident dosimetry

International Nuclear Information System (INIS)

2002-06-01

The French institute of radioprotection and nuclear safety (IRSN) has carried out in June 2002 an international intercomparison program for the testing of the physical and biological accident dosimetry techniques. The intercomparison is jointly organized by the IRSN and the OECD-NEA with the sustain of the European commission and the collaboration of the CEA centre of Valduc (France). About 30 countries have participated to this program. Each country has supplied its own dosimeters and biological samples which have been irradiated using the Silene reactor of CEA-Valduc or a 60 Co source. These experiments allow to test the new dosimetric techniques that have been developed since the previous intercomparison program (1993) and to confirm or improve the performances of older techniques. Aside from the intercomparison exercise, this report makes a status of the known radiological accidents and of the effects of high doses of ionizing radiations on human health (symptoms, therapeutics). It explains the phenomenology of criticality accidents, the prevention means, and the history of such accidents up to the Tokai-Mura one in 1999. Finally, the dosimetry of criticality is presented with its physical and biological techniques. (J.S.)

Accident and emergency management

International Nuclear Information System (INIS)

Andersen, V.; Moellenbach, K.; Heinonen, R.; Jakobsson, S.; Kukko, T.; Berg, Oe.; Larsen, J.S.; Westgaard, T.; Magnusson, B.; Andersson, H.; Holmstroem, C.; Brehmer, B.; Allard, R.

1988-06-01

There is an increasing potential for severe accidents as the industrial development tends towards large, centralised production units. In several industries this has led to the formation of large organisations which are prepared for accidents fighting and for emergency management. The functioning of these organisations critically depends upon efficient decision making and exchange of information. This project is aimed at securing and possibly improving the functionality and efficiency of the accident and emergency management by verifying, demonstrating, and validating the possible use of advanced information technology in the organisations mentioned above. With the nuclear industry in focus the project consists of five main activities: 1) The study and detailed analysis of accident and emergency scenarios based on records from incidents and rills in nuclear installations. 2) Development of a conceptual understanding of accident and emergency management with emphasis on distributed decision making, information flow, and control structure sthat are involved. 3) Development of a general experimental methodology for evaluating the effects of different kinds of decision aids and forms of organisation for emergency management systems with distributed decision making. 4) Development and test of a prototype system for a limited part of an accident and emergency organisation to demonstrate the potential use of computer and communication systems, data-base and knowledge base technology, and applications of expert systems and methods used in artificial intelligence. 5) Production of guidelines for the introduction of advanced information technology in the organisations based on evaluation and validation of the prototype system. (author)

The nature of reactor accidents

International Nuclear Information System (INIS)

Domaratzki, Z.; Campbell, F.R.; Atchison, R.J.

1981-01-01

Reactor accidents are events which result in the release of radioactive material from a nuclear power plant due to the failure of one or more critical components of that plant. The failures, depending on their number and type, can result in releases whose consequences range from negligible to catastrophic. By way of examples, this paper describes four specific accidents which cover this range of consequence: failure of a reactor control system, loss of coolant, loss of coolant with impaired containment, and reactor core meltdown. For each a possible sequence of events and an estimate of the expected frequency are presented

Calibration of the indium foil used for criticality accident dosimetry in the UCC-ND employee identification badge

International Nuclear Information System (INIS)

Ryan, M.T.; Butler, H.M.; Gupton, E.D.; Sims, C.S.

1982-05-01

The UCC-ND Employee Identification Badge contains an indium foil disc that is intended for use as a dosimetry screening device in the event of a criticality accident. While it is recognized that indium is not a precise mixed neutron-gamma dosimeter, its activation by neutrons provides adequate means for separating potentially exposed persons into three groups. These groups are: (1) personnel exposed below annual dose limits, (2) personnel exposed above annual dose limits but below 25 rem, and (3) personnel exposed above 25 rem. This screening procedure is designed to facilitate dosimeter processing in order to meet regulatory reporting requirements. A quick method of interpreting induced activity measurements is presented and discussed

Accidents - Chernobyl accident

International Nuclear Information System (INIS)

2004-01-01

This file is devoted to the Chernobyl accident. It is divided in four parts. The first part concerns the accident itself and its technical management. The second part is relative to the radiation doses and the different contaminations. The third part reports the sanitary effects, the determinists ones and the stochastic ones. The fourth and last part relates the consequences for the other European countries with the case of France. Through the different parts a point is tackled with the measures taken after the accident by the other countries to manage an accident, the cooperation between the different countries and the groups of research and studies about the reactors safety, and also with the international medical cooperation, specially for the children, everything in relation with the Chernobyl accident. (N.C.)

Detection and analysis of black spots with even small accident figures. Contribution to the Seminar on Short-term and Area-wide Evaluation of Safety Measures, Amsterdam, April 19-21, 1982, p. 75-84.

NARCIS (Netherlands)

Oppe, S.

1982-01-01

In order to detect accident black spots we have to know the probability of an accident for a traffic situation of some kind, or the mean number of accidents for some unit of time. In almost all procedures known to us, the various road locations are treated as isolated spots. With small accident

Severe Accident Management System On-line Network SAMSON

International Nuclear Information System (INIS)

Silverman, Eugene B.

2004-01-01

SAMSON is a computational tool used by accident managers in the Technical Support Centers (TSC) and Emergency Operations Facilities (EOF) in the event of a nuclear power plant accident. SAMSON examines over 150 status points monitored by nuclear power plant process computers during a severe accident and makes predictions about when core damage, support plate failure, and reactor vessel failure will occur. These predictions are based on the current state of the plant assuming that all safety equipment not already operating will fail. SAMSON uses expert systems, as well as neural networks trained with the back propagation learning algorithms to make predictions. Training on data from an accident analysis code (MAAP - Modular Accident Analysis Program) allows SAMSON to associate different states in the plant with different times to critical failures. The accidents currently recognized by SAMSON include steam generator tube ruptures (SGTRs), with breaks ranging from one tube to eight tubes, and loss of coolant accidents (LOCAs), with breaks ranging from 0.0014 square feet (1.30 cm 2 ) in size to breaks 3.0 square feet in size (2800 cm 2 ). (author)

Aspects of severe accidents in transmutation systems

International Nuclear Information System (INIS)

Wider, H.U.; Karlson, J.; Jones, A.V.

2001-01-01

The different types of transmutation systems under investigation include accelerator driven (ADS) and critical systems. To switch off an accelerator in case of an accident initiation is quite important for all accidents. For a fast ADS the grace times available for doing so depend strongly on the total heat capacity and the natural circulation capability of the primary coolant. Cooling with heavy metal Pb-Bi has considerable advantages in this regard compared to gas cooling. Moreover it allows passive ex-vessel cooling with natural air or water circulation. In the remote likelihood of fuel melting, oxide fuel appears to mix with the Pb-Bi coolant. Fast critical systems that are cooled by Pb-Bi will automatically shut off if the flow or heat sink is lost. Reactivity accidents can be limited by a low total control rod worth. High temperature reactors can achieve only incomplete burning of actinides. If an accelerator is added to increase burn-up, a fast spectrum region is needed, which has a low heat capacity. (author)

Learning lessons from accidents with a human and organisational factors perspective: deficiencies and failures of operating experience feedback systems

International Nuclear Information System (INIS)

Dechy, N.; Rousseau, J.M.; Jeffroy, F.

2012-01-01

This paper aims at reminding the failures of operating experience feedback (OEF) systems through the lessons of accidents and provides a framework for improving the efficiency of OEF processes. The risk is for example to miss lessons from other companies and industrial sectors, or to miss the implementation of adequate corrective actions with the risk to repeat accidents. Most of major accidents have been caused by a learning failure or other organisational factors as a contributing cause among several root causes. Some of the recurring organisational factors are: -) poor recognition of critical components, of critical activities or deficiency in anticipation and detection of errors, -) excessive production pressure, -) deficiency of communication or lack of quality of dialogue, -) Excessive formalism, -) organisational complexity, -) learning deficiencies (OEF, closing feedback loops, lack of listening of whistle-blowers). Some major accidents occurred in the nuclear industry. Although the Three Mile Island accident has multiple causes, in particular, an inappropriate design of the man-machine interface, it is a striking example of the loss of external lessons from incidents. As for Fukushima it is too early to have established evidence on learning failures. The systematic study and organisational analysis of OEF failures in industrial accidents whatever their sector has enabled us to provide a framework for OEF improvements. Five key OEF issues to improve in priority: 1) human and organisational factors analysis of the root causes of the events, 2) listening to the field staff, dissenting voices and whistle-blowers, 3) monitoring of the external events that provide generic lessons, 4) building an alive memory through a culture of accidents with people who become experiences pillars, and 5) the setting of external audit or organisational analysis of the OEF system by independent experts. The paper is followed by the slides of the presentation

Researches and Applications of ESR Dosimetry for Radiation Accident Dose Assessment

International Nuclear Information System (INIS)

Wu, K.; Guo, L.; Cong, J.B.; Sun, C.P.; Hu, J.M.; Zhou, Z.S.; Wang, S.; Zhang, Y.; Zhang, X.; Shi, Y.M.

1998-01-01

The aim of this work was to establish methods suitable for practical dose assessment of people involved in ionising radiation accidents. Some biological materials of the human body and materials possibly carried or worn by people were taken as detection samples. By using electron spin resonance (ESR) techniques, the basic dosimetric properties of selected materials were investigated in the range above the threshold dose of human acute haemopoietic radiation syndrome. The dosimetric properties involved included dose response properties of ESR signals, signal stabilities, distribution of background signals, the lowest detectable dose value, radiation conditions, environmental effects on the detecting process, etc. Several practical dose analytical indexes and detecting methods were set up. Some of them (bone, watch glass and tooth enamel) had also been successfully used in the dose assessment of people involved in three radiation accidents, including the Chernobyl reactor accident. This work further proves the important role of ESR techniques in radiation accident dose estimation. (author)

Emergency Response to Radioactive Material Transport Accidents

International Nuclear Information System (INIS)

EL-shinawy, R.M.K.

2009-01-01

Although transport regulations issued by IAEA is providing a high degree of safety during transport opertions,transport accidents involving packages containing radioactive material have occurred and will occur at any time. Whenever a transport accident involving radioactive material accurs, and many will pose no radiation safety problems, emergency respnose actioms are meeded to ensure that radiation safety is maintained. In case of transport accident that result in a significant relesae of radioactive material , loss of shielding or loss of criticality control , that consequences should be controlled or mitigated by proper emergency response actions safety guide, Emergency Response Plamming and Prepardness for transport accidents involving radioactive material, was published by IAEA. This guide reflected all requirememts of IAEA, regulations for safe transport of radioactive material this guide provide guidance to the publicauthorites and other interested organziation who are responsible for establishing such emergency arrangements

Radioactive contamination from Chernobyl accident over Alexandria city

International Nuclear Information System (INIS)

Ammar, E.A.; El-Khatib, A.M.; Wahba, A.G.; Elraey, M.

1987-01-01

The concentration of radioactive contamination in air resulting from the Chernobyl accident has been followed up. A sudden and sharp increase was detected seven days after the start of the accident. This increase amounted to about 650 times the normal air-borne activity. (author)

Development of an accident management expert system for containment assessment

International Nuclear Information System (INIS)

Nelson, W.R.; Sebo, D.E.; Haney, L.N.

1987-01-01

The United States Nuclear Regulatory Commission (USNRSC) is sponsoring a program at the Idaho National Engineering Laboratory (INEL) to develop an accident management expert system. The intended users of the system are the personnel of the NRC Operations Center in Washington, D.C. The expert system will be used to help NRC personnel monitor and evaluate the status and management of the containment during a severe reactor accident. The knowledge base will include severe accident knowledge regarding the maintenance of the critical safety functions, especially containment integrity, during an accident. This paper summarizes the concepts that have been developed for the accident management expert system, and the plans that have been developed for its implementation

Some Examples of Accident Analyses for RB Reactor

International Nuclear Information System (INIS)

Pesic, M.

2002-01-01

The RB reactor is heavy water critical assembly operated in the Vinca Institute of Nuclear Sciences, Belgrade, Yugoslavia, since April 1959. The first Safety Analysis Report of the RB critical assembly was prepared in 1961/62. But, the first accidental analysis was done in late 1958 in aim the examine power transient and total equivalent doses received by the staff during the reactivity accident occurred on October 15, 1958. Since 1960, the RB reactor is modified few times. Beside initial natural uranium metal fuel rods, new fuel (TVR-S types) from 2% enriched metal uranium and 80% enriched UO 2 were available since 1962 and 1976, respectively. Also, modifications in control and safety systems of the reactor were done occasionally. Special reactor cores were created using all three types of fuel elements, among them, the coupled fast-thermal ones. Nuclear Safety Committee of the Vinca Institute, an independent regulatory body approved for usage all these modifications of the RB reactor. For those decisions of the Committee, the Preliminary Safety Analysis Reports were prepared that, beside proposed technical modifications and new regulation rules had included analyses of various possible accidents. Special attention is given and new methodology was proposed for thoroughly analyses of design based accidents related to coupled fast-thermal cores, that include reactor central zones filled by fuel elements without moderator. In these accidents, during assumed flooding of the fast zone by moderator, a very high reactivity could be inserted in the system with very high reactivity rate. It was necessary to provide that the safety system of the reactor had fast response to that accident and had enough high (negative) reactivity to shut down the reactor timely. In this paper, a brief overview of some accidents, methodology and computation tools used for the accident analyses at RB reactor are given. (author)

Radiological accident 'The Citadel' medical aspects

International Nuclear Information System (INIS)

Cardenas Herrera, Juan; Fernandez, Isis M.; Lopez, Gladys; Garcia, Omar; Lamadrid, Ana I.; Ramos, Enma O.; Villa, Rosario; Giron, Carmen M.; Escobar, Myrian; Zerpa, Miguel; Romero, Argenis H.; Medina, Julio; Laurenti, Zenia; Oliva, Maria T.; Sierra, Nitza; Lorenzo, Alexis

2008-01-01

The work exposes the medical actions carried out in the mitigation of the consequences of the accident and its main results. In a facility of storage of radioactive waste in Caracas, Venezuela, it was happened a radiological accident. This event caused radioactive contamination of the environment, as well as the irradiation and radioactive contamination of at least 10 people involved in the fact, in its majority children. Cuban institutions participated in response to the accident. Among the decisions adopted by the team of combined work Cuban-Venezuelan, we find the one of transferring affected people to Cuba, for their dosimetric and medical evaluation. Being designed a work strategy to develop the investigations to people affected by the radiological accident, in correspondence with the circumstances, magnitude and consequences of the accident. The obtained main results are: 100% presented affectations in its health, not associate directly to the accident, although the accident influenced in its psychological state. In 3 of studied people they were detected radioactive contamination with Cesium -137 with dose among 2.01 X 10-4 Sv up to 2.78 X 10-4 Sv. This accident demonstrated the necessity to have technical capacities to face these events and the importance of the international solidarity. (author)

Measurements of 60Co in spoons activated by neutrons during the JCO criticality accident at Tokai-mura in 1999

International Nuclear Information System (INIS)

Gasparro, J.; Hult, M.; Komura, K.; Arnold, D.; Holmes, L.; Johnston, P.N.; Laubenstein, M.; Neumaier, S.; Reyss, J.-L.; Schillebeeckx, P.; Tagziria, H.; Van Britsom, G.; Vasselli, R.

2004-01-01

Neutron activated items from the vicinity of the place where the JCO criticality accident occurred have been used to determine the fluence of neutrons around the facility and in nearby residential areas. By using underground laboratories for measuring the activation products, it is possible to extend the study to also cover radionuclides with very low activities from long-lived radionuclides. The present study describes γ-ray spectrometry measurements undertaken in a range of underground laboratories for the purpose of measuring 60 Co more than 2 years after the criticality event. The measurements show that neutron fluence determined from 60 Co activity is in agreement with previous measurements using the short-lived radionuclides 51 Cr and 59 Fe. Limits on contamination of the samples with 60 Co are evaluated and shown to not greatly affect the utility of neutron fluence determinations using 60 Co activation

Measurements of 60Co in spoons activated by neutrons during the JCO criticality accident at Tokai-mura in 1999.

Science.gov (United States)

Gasparro, J; Hult, M; Komura, K; Arnold, D; Holmes, L; Johnston, P N; Laubenstein, M; Neumaier, S; Reyss, J-L; Schillebeeckx, P; Tagziria, H; Van Britsom, G; Vasselli, R

2004-01-01

Neutron activated items from the vicinity of the place where the JCO criticality accident occurred have been used to determine the fluence of neutrons around the facility and in nearby residential areas. By using underground laboratories for measuring the activation products, it is possible to extend the study to also cover radionuclides with very low activities from long-lived radionuclides. The present study describes gamma-ray spectrometry measurements undertaken in a range of underground laboratories for the purpose of measuring (60)Co more than 2 years after the criticality event. The measurements show that neutron fluence determined from (60)Co activity is in agreement with previous measurements using the short-lived radionuclides (51)Cr and (59)Fe. Limits on contamination of the samples with (60)Co are evaluated and shown to not greatly affect the utility of neutron fluence determinations using (60)Co activation.

A cascading failure model for analyzing railway accident causation

Science.gov (United States)

Liu, Jin-Tao; Li, Ke-Ping

2018-01-01

In this paper, a new cascading failure model is proposed for quantitatively analyzing the railway accident causation. In the model, the loads of nodes are redistributed according to the strength of the causal relationships between the nodes. By analyzing the actual situation of the existing prevention measures, a critical threshold of the load parameter in the model is obtained. To verify the effectiveness of the proposed cascading model, simulation experiments of a train collision accident are performed. The results show that the cascading failure model can describe the cascading process of the railway accident more accurately than the previous models, and can quantitatively analyze the sensitivities and the influence of the causes. In conclusion, this model can assist us to reveal the latent rules of accident causation to reduce the occurrence of railway accidents.

Re criticality assessment following reactor core damage in Fukushima unit 2

International Nuclear Information System (INIS)

Jeong, Hae Sun; Song, Jin Ho; Park, Chang Je; Ha, Kwang Soon; Song, Yong Mann; Ryu, Eun Hyun

2012-01-01

Following the severe core damage accident at the Fukushima nuclear power plants (NPPs), many researchers have studied a possible Re criticality caused by core melting or corium. However, no one can accurately examine the internal conditions of the reactor vessel, and thus there have been different opinions from some organizations depending on their assumption and analysis methods. If there is a potential Re criticality in the reactor vessel, some counter plans for the accident management should be established to prevent and mitigate re criticality, and to return the plant to a safe and stable state. In this study, the criticality level following a severe core damage accident was first analyzed using the MCNPX 2.6.0 code. Based on this result, practical strategies in terms of accident management were obtained by charging soluble boron (H 3B O 3) into re flooded water

Management of foodstuffs after nuclear accidents

International Nuclear Information System (INIS)

1991-01-01

A model for the management of foodstuffs after nuclear accidents is presented. The model is a synthesis of traditions and principles taken from both radioactive protection and management of food. It is based on cooperation between the Nordic countries and on practical experience gained from the Chernobyl accident. The aim of the model is to produce a basis for common plans for critical situations based on criteria for decision making. In the case of radioactive accidents it is important that the protection of the public and of the society is handled in a positive way. The model concerns production, marketing and consumption of food and beverage. The overall aim is that the radiation doses should be as low and harmless to health for individual members of the public. (CLS) 35 refs

Program of nuclear criticality safety experiment at JAERI

International Nuclear Information System (INIS)

Kobayashi, Iwao; Tachimori, Shoichi; Takeshita, Isao; Suzaki, Takenori; Ohnishi, Nobuaki

1983-11-01

JAERI is promoting the nuclear criticality safety research program, in which a new facility for criticality safety experiments (Criticality Safety Experimental Facility : CSEF) is to be built for the experiments with solution fuel. One of the experimental researches is to measure, collect and evaluate the experimental data needed for evaluation of criticality safety of the nuclear fuel cycle facilities. Another research area is a study of the phenomena themselves which are incidental to postulated critical accidents. Investigation of the scale and characteristics of the influences caused by the accident is also included in this research. The result of the conceptual design of CSEF is summarized in this report. (author)

First days of the Chernobyl accident. Private experience

International Nuclear Information System (INIS)

Karpan, Nikolay

2013-01-01

Ex-deputy chief engineer of Chernobyl NPP described the time-series personal experience of the fourth unit accident on 26 April, 1986. He was informed the accident at home at 4 o'clock. He came to the plant at 7 o'clock. He and other newcomers were no informed about what happened at the plant and about details of the accident from top manager of the plant. He gathered important information about the accident from people that were eyewitness of the accident and recorded their evidences. He reported to head engineer and his deputy that solution of boron acid could be brought into reactor for suppression of the chain reaction. Director of NPP asked authorities to bring boron acid to the plant, but the boron acid was not received before the chain reaction. The critical state began approximately 20 in the evening. After 4 hours of the critical state exposition dose rate of gamma radiation was ten times from 20 R/h in the morning and middle of day to 200 R/h. He consider as the first fault of the Governmental Commission was the absence of efforts for bringing boron to gorges of fuel and to shaft of reactor. The second fault was that protective countermeasures for city population protection were not undertaken. The authorities of Chernobyl began to wait for decisions of higher authorities. This means that responsibility was moved to them. (N.T)

Identification of NPP accidents using support vector classification

Energy Technology Data Exchange (ETDEWEB)

Back, Ju Hyun; Yoo, Kwae Hwan; Na, Man Gyun [Chosun University, Gwangju (Korea, Republic of)

2016-10-15

In case of the accidents that happens in a nuclear power plants (NPPs), it is very important to identify its accidents for the operator. Therefore, in order to effectively manage the accidents, the initial short time trends of major parameters have to be observed and NPP accidents have to accurately be identified to provide its information to operators and technicians. In this regard, the objective of this study is to identify the accidents when the accidents happen in NPPs. In this study, we applied the support vector classification (SVC) model to classify the initiating events of critical accidents such as loss of coolant accidents (LOCA), total loss of feedwater (TLOFW), station blackout (SBO), and steam generator tube rupture (SGTR). Input variables were used as the initial integral value of the signal measured in the reactor coolant system (RCS), steam generator, and containment vessel after reactor trip. The proposed SVC model is verified by using the simulation data of the modular accident analysis program (MAAP4) code. In this study, the proposed SVC model is verified by using the simulation data of the modular accident analysis program (MAAP4) code. We used an initial integral value of the simulated sensor signals to identify the NPP accidents. The training data was used to train the SVC model. And, the trained model was confirmed using the test data. As a result, it was known that it can accurately classify five events.

Some issues on the Law for the Regulations of Nuclear Source Material, Nuclear Fuel Material and Reactors Amendment after JCO criticality accident

International Nuclear Information System (INIS)

Tanabe, Tomoyuki

2001-01-01

As the Amendment of the Law for the Regulation of Nuclear Material, Nuclear Fuel Material and Reactors on an opportunity of the JCO criticality accident can be almost evaluated at a viewpoint of upgrading on effectiveness of safety regulation, it is thought to remain a large problem to rely on only enforcement of regulation due to amendment of the Law at future accident. In future, it can be also said to be important subjects to further expand a philosophy on the regulation (material regulation) focussed to hazards of nuclear material itself, not only to secure effectiveness on the multi-complementary safety regulation due to the administrative agency and the Nuclear Safety Commission but also to prepare a mechanism reflexible of a new information to the safety regulation, and to prepare a mechanism to assist adequate business execution and so forth of enterprises. (G.K.)

Instrumentation for the follow-up of severe accidents

International Nuclear Information System (INIS)

Munoz Sanchez, A.; Nino Perote, R.

2000-01-01

During severe accidents, it is foreseeable that the instrumentation installed in a plant is subjected to conditions which are more hostile than those for which the instrumentation was designed and qualified. Moreover, new, specific instrumentation is required to monitor variables which have not been considered until now, and to control systems which lessen the consequences of severe accidents. Both existing instrumentation used to monitor critical functions in design basis accident conditions and additional instrumentation which provides the information necessary to control and mitigate the consequences of severe accidents, have to be designed to withstand such conditions, especially in terms of measurements range, functional characteristics and qualification to withstand pressure and temperature loads resulting from steam explosion, hydrogen combustion/explosion and high levels of radiation over long periods of time. (Author)

Nineteenth nuclear accident dosimetry intercomparison study, August 9-13, 1982

International Nuclear Information System (INIS)

Greene, R.T.; Sims, C.C.; Swaja, R.E.

1983-11-01

The Nineteenth Nuclear Accident Dosimetry Intercomparison Study was held August 9 to 13, 1982, at the Oak Ridge National Laboratory using the Health Physics Research Reactor operated in the pulse mode to simulate nuclear criticality accidents. Participants from eight organizations measured neutron and gamma doses at air stations and on phantoms for three different shielding conditions. Measured results were compared to nuclear industry guidelines for criticality accident dosimeters which suggest accuracies of +-25% for neutron dose and +-20% for gamma dose. Seventy-two percent of the neutron dose measurements using foil activation, sodium activation, hair sulfur activation, and thermoluminescent methods met the guidelines while less than 40% of the gamma dose measurements were within +-20% of reference values. The softest neutron energy spectrum (also lowest neutron/gamma dose ratio) provided the most difficulty in measuring neutron and gamma doses. Results of this study indicate the need for continued intercomparison and testing of nuclear accident dosimetry systems and for training of evaluating personnel. 14 references, 7 figures, 16 tables

Neural Network Based Intrusion Detection System for Critical Infrastructures

Energy Technology Data Exchange (ETDEWEB)

Todd Vollmer; Ondrej Linda; Milos Manic

2009-07-01

Resiliency and security in control systems such as SCADA and Nuclear plant’s in today’s world of hackers and malware are a relevant concern. Computer systems used within critical infrastructures to control physical functions are not immune to the threat of cyber attacks and may be potentially vulnerable. Tailoring an intrusion detection system to the specifics of critical infrastructures can significantly improve the security of such systems. The IDS-NNM – Intrusion Detection System using Neural Network based Modeling, is presented in this paper. The main contributions of this work are: 1) the use and analyses of real network data (data recorded from an existing critical infrastructure); 2) the development of a specific window based feature extraction technique; 3) the construction of training dataset using randomly generated intrusion vectors; 4) the use of a combination of two neural network learning algorithms – the Error-Back Propagation and Levenberg-Marquardt, for normal behavior modeling. The presented algorithm was evaluated on previously unseen network data. The IDS-NNM algorithm proved to be capable of capturing all intrusion attempts presented in the network communication while not generating any false alerts.

The program of international intercomparison of accident dosimetry; Le programme d'intercomparaison internationale de dosimetrie d'accident 10-12 juin 2002

Energy Technology Data Exchange (ETDEWEB)

NONE

2002-06-01

The French institute of radioprotection and nuclear safety (IRSN) has carried out in June 2002 an international intercomparison program for the testing of the physical and biological accident dosimetry techniques. The intercomparison is jointly organized by the IRSN and the OECD-NEA with the sustain of the European commission and the collaboration of the CEA centre of Valduc (France). About 30 countries have participated to this program. Each country has supplied its own dosimeters and biological samples which have been irradiated using the Silene reactor of CEA-Valduc or a {sup 60}Co source. These experiments allow to test the new dosimetric techniques that have been developed since the previous intercomparison program (1993) and to confirm or improve the performances of older techniques. Aside from the intercomparison exercise, this report makes a status of the known radiological accidents and of the effects of high doses of ionizing radiations on human health (symptoms, therapeutics). It explains the phenomenology of criticality accidents, the prevention means, and the history of such accidents up to the Tokai-Mura one in 1999. Finally, the dosimetry of criticality is presented with its physical and biological techniques. (J.S.)

Chromosome aberration analysis in persons exposed to low-level radiation from the JCO criticality accident in Tokai-mura

International Nuclear Information System (INIS)

Sasaki, Masao S.; Hayata, Isamu; Kamada, Nanao; Kodama, Yoshiaki; Kodama, Seiji

2001-01-01

Chromosome aberrations were studied in peripheral blood lymphocytes of 43 persons who were exposed to low-level radiation of mixed neutrons and γ-rays resulting from the JCO criticality accident. When the age-adjusted frequencies of dicentric and ring chromosomes were compared with the dose calibration curve established in vitro for 60 Co γ-rays as a reference radiation, a significant correlation was observed between the chromosomally estimated doses and the documented doses evaluated by physical means. The regression coefficient of the chromosomal doses against the documented doses, 1.47±0.33, indicates that the relative biological effectiveness of fission neutrons at low doses is considerably higher than that currently adopted in the radiation protection standard. (author)

Root cause analysis of JCO accident based on decision-making model

International Nuclear Information System (INIS)

Kohda, Takehisa; Inoue, Koichi; Nojiri, Yoshihiko

2000-01-01

This paper discusses root causes of the JCO accident by considering the reasons why the workers made their decision to choose the illegal actions leading to a criticality accident. Analyzing their decision process compared with the normal decision process, the direct cause of their incorrect decision is estimated to be the lack of knowledge about the danger of nuclear materials and the criticality. Further, the lack of knowledge is considered to be due to organizational or environmental factors such as (a) the ignorance of safety by the overall JCO company which pursued low costs and high profit, (b) the JCO's custom and practice of modifying operational rules without permission, and (c) the JCO's inappropriate training or education where the criticality or its danger was not taught. All these background factors are related to the overconfidence of plant safety, a false trust that such a criticality accident will never occur at the plant. Since the recognition of the danger or risk of a system is considered to be the starting point for its safety management and operation, all information about the danger and safety should be correctly communicated to everyone related to the system. (author)

How the radiological accident of Goiania was initially determined

International Nuclear Information System (INIS)

Ferreira, W.M.

2000-01-01

Mainly the initial actions adopted to minimise the consequences of radiological accident involving the public are very important for bringing the situation to the normality. In this work the author presents a short history about the radiological accident with a 137 Cs source occurred in the city of Goiania, Brazil in 1987 as well as the actions adopted by him during the first hours after the detection of the accident. (author)

Simulation of hypothetical criticality accidents involving homogeneous damp low-enriched UO2 powder systems

International Nuclear Information System (INIS)

Basoglu, B.; Brewer, R.W.; Haught, C.F.; Hollenbach, D.F.; Wilkinson, A.D.; Dodds, H.L.; Pasqua, P.F.

1994-01-01

This paper describes the development of a computer model for predicting the excursion characteristics of a postulated, hypothetical, critically accident involving a homogeneous mixture of low-enriched UO 2 powder and water contained in a cylindrical blender. The model uses point neutronics coupled with simple lumped-parameter thermal-hydraulic feedback. The temperature of the system is calculated using a simple time-dependent energy balance where two extreme conditions for the thermal behavior of the system are considered, which bound the real life situation. Using these extremes, three different models are developed. To evaluate the models, the authors compared the results with the results of the POWDER code, which was developed by the Commissariat a l'Energie Atomique/United Kingdom Atomic Energy Authority (CEA/UKAEA) for damp powder systems. The agreement in these comparisons is satisfactory. Results of the excursion studies in this work show that approximately 10 19 fissions occur as a result of accidental water ingress into powder blenders containing 5,000 kg of low-enriched (5%) UO 2 powder

TL detectors for gamma-ray dose measurements in critically accidents

International Nuclear Information System (INIS)

Miljanic, S.; Knezevic, Z.; Zorko, B.; Gregori, B.

2005-01-01

Full text: Determination of gamma-ray dose in mixed neutron + gamma-ray fields is still a challenging task. Dosemeters used for gamma-ray dosimetry are usually in some extent sensitive to neutrons and their response variations depend on neutron energy i.e. on neutron spectra. Besides, it is necessary to take into account the energy dependence of dosimeter responses to gamma-rays. To reduce all these influences, design of dosemeter holders is of special importance. In this work, several types of thermoluminescent detectors (TLD) placed in different holders used for gamma-ray dose determination in mixed fields were examined. Dosemeters were from three different institutions: Ruder Boscovic Institute (RBI), Croatia, Jozef Stefan Institute (JSI), Slovenia and Autoridad Regulatoria Nuclear (ARN), Argentina. All dosemeters were irradiated during the International Intercomparison of Criticality Accident Dosimetry Systems at the SILENE Reactor, Valduc, June 2002. At that exercise three accidental scenarios were reproduced: bare reactor, free evolution; lead shielded reactor, steady state; and lead shielded reactor, free evolution. In each irradiation dosemeters were exposed placed on the front of phantom and 'free-in-air'. Also, dosemeters were irradiated in a pure gamma ray field of 60 Co source. Following types of TLDs were used: 7 LiF (TLD-700), CaF 2 :Mn and AI 2 O 3 :Mg,Y - all from RBI; CaF 2 :Mn from JSI and 7 LiF (TLD-700) from ARN. Reported doses were compared with the reference values as well as with the mean participants' values. The results show satisfactory agreement with other dosimetry systems used in the Intercomparison. The influence of different types of holders and applied corrections of dosemeters' readings are discussed. (author)

Applications of PRA in nuclear criticality safety

International Nuclear Information System (INIS)

McLaughlin, T.P.

1992-01-01

Traditionally, criticality accident prevention at Los Alamos has been based on a thorough review and understanding of proposed operations of changes to operations, involving both process supervision and criticality safety staff. The outcome of this communication was usually an agreement, based on professional judgement, that certain accident sequences were credible and had to be reduced in likelihood either by administrative controls or by equipment design and others were not credible, and thus did not warrant expenditures to further reduce their likelihood. The extent of analysis and documentation was generally in proportion to the complexity of the operation but did not include quantified risk assessments. During the last three years nuclear criticality safety related Probabilistic Risk Assessments (PRAs) have been preformed on operations in two Los Alamos facilities. Both of these were conducted in order to better understand the cost/benefit aspects of PRA's as they apply to largely ''hands-on'' operations with fissile material for which human errors or equipment failures significant to criticality safety are both rare and unique. Based on these two applications and an appreciation of the historical criticality accident record (frequency and consequences) it is apparent that quantified risk assessments should be performed very selectively

Management and Operational Control of Criticality

Energy Technology Data Exchange (ETDEWEB)

Daniels, J. T. [Authority Health and Safety Branch, United Kingdom Atomic Energy Authority, Risley, Lancs. (United Kingdom)

1966-05-15

The evidence of the six process criticality accidents that have been reported to date shows that, without exception, they have been due to the failure of operational controls. In no instance has a criticality accident in processing been due to the use of wrong data 01 inaccurate calculation. Criticality accidents are least likely to occur in the production stream and are more likely to be associated with ancillary equipment and operations. Important as correct criticality calculations are, there are many other considerations which require the exercise of judgement in establishing the operational environment. No operation involving fissile material should be permitted without a formal review resulting in a documented statement of (a) the environmental assessment, (b) the nuclear safety arguments which demonstrate safety under that environment, and (c) the operational requirements which will ensure the validity of (b) under the conditions of (a). To ensure the continued viability of the environmental assessment and the continued reliability of clearance conditions there should be close supervision by operating management, and periodic checks made by site nuclear safety staff. Additionally, there should be periodic and systematic examinations by competent persons who are not responsible to the overall management of the site. (author)

Accident management for severe accidents

International Nuclear Information System (INIS)

Bari, R.A.; Pratt, W.T.; Lehner, J.; Leonard, M.; Disalvo, R.; Sheron, B.

1988-01-01

The management of severe accidents in light water reactors is receiving much attention in several countries. The reduction of risk by measures and/or actions that would affect the behavior of a severe accident is discussed. The research program that is being conducted by the US Nuclear Regulatory Commission focuses on both in-vessel accident management and containment and release accident management. The key issues and approaches taken in this program are summarized. 6 refs

Modeling secondary accidents identified by traffic shock waves.

Science.gov (United States)

Junhua, Wang; Boya, Liu; Lanfang, Zhang; Ragland, David R

2016-02-01

The high potential for occurrence and the negative consequences of secondary accidents make them an issue of great concern affecting freeway safety. Using accident records from a three-year period together with California interstate freeway loop data, a dynamic method for more accurate classification based on the traffic shock wave detecting method was used to identify secondary accidents. Spatio-temporal gaps between the primary and secondary accident were proven be fit via a mixture of Weibull and normal distribution. A logistic regression model was developed to investigate major factors contributing to secondary accident occurrence. Traffic shock wave speed and volume at the occurrence of a primary accident were explicitly considered in the model, as a secondary accident is defined as an accident that occurs within the spatio-temporal impact scope of the primary accident. Results show that the shock waves originating in the wake of a primary accident have a more significant impact on the likelihood of a secondary accident occurrence than the effects of traffic volume. Primary accidents with long durations can significantly increase the possibility of secondary accidents. Unsafe speed and weather are other factors contributing to secondary crash occurrence. It is strongly suggested that when police or rescue personnel arrive at the scene of an accident, they should not suddenly block, decrease, or unblock the traffic flow, but instead endeavor to control traffic in a smooth and controlled manner. Also it is important to reduce accident processing time to reduce the risk of secondary accident. Copyright © 2015 Elsevier Ltd. All rights reserved.

Measurements of {sup 60}Co in spoons activated by neutrons during the JCO criticality accident at Tokai-mura in 1999

Energy Technology Data Exchange (ETDEWEB)

Gasparro, J.; Hult, M. E-mail: mikael.hult@irmm.jrc.be; Komura, K.; Arnold, D.; Holmes, L.; Johnston, P.N.; Laubenstein, M.; Neumaier, S.; Reyss, J.-L.; Schillebeeckx, P.; Tagziria, H.; Van Britsom, G.; Vasselli, R

2004-07-01

Neutron activated items from the vicinity of the place where the JCO criticality accident occurred have been used to determine the fluence of neutrons around the facility and in nearby residential areas. By using underground laboratories for measuring the activation products, it is possible to extend the study to also cover radionuclides with very low activities from long-lived radionuclides. The present study describes {gamma}-ray spectrometry measurements undertaken in a range of underground laboratories for the purpose of measuring {sup 60}Co more than 2 years after the criticality event. The measurements show that neutron fluence determined from {sup 60}Co activity is in agreement with previous measurements using the short-lived radionuclides {sup 51}Cr and {sup 59}Fe. Limits on contamination of the samples with {sup 60}Co are evaluated and shown to not greatly affect the utility of neutron fluence determinations using {sup 60}Co activation.

[Drugs and occupational accident].

Science.gov (United States)

Bratzke, H; Albers, C

1996-02-01

In a case of a fatal occupational accident (construction worker, fall from roof, urine test positive for cocaine and THC, e.g. cannabis) the question arised to what extent those drug-related occupational accidents occur. In the literature only few cases, mainly dealing with cannabis influence, have been reported, however, a higher number is suspected. Cocaine and other stimulating drugs (amphetamine) are more often used to increase physical fitness. By direct or indirect interference with vigilance these compounds may provoke accidents. Due to the lack of a legal basis proving of the influence of drugs at the working place is still very limited, although highly sensitive chemical-toxicological assay procedures are available to detect even the chronic abuse (in hair). In the general conditions of accident insurances a compensation is excluded when alcohol is involved, but drugs are not mentioned. It is indeed difficult to establish a concentration limit for drugs like that existing for alcohol (1.1%). In each case the assay of the drug involved and exact knowledge of its specific effects is in an essential prerequisite to prove the causal relationship.

Nuclear criticality evacuation with telemonitoring and microprocessors

International Nuclear Information System (INIS)

Fergus, R.W.; Moe, H.J. Sr.

1979-01-01

At Argonne National Laboratory, criticality alarms are required at widely separated locations to evacuate personnel in case of accident while emergency teams or maintenance personnel respond from a central location. The system functions have been divided in a similar manner. The alarm site hardware can independently detect a criticality and sound the evacuation signal while general monitoring and routine tests are handled by a communication link to a central monitoring station. The radiation detectors and evacuation sounders at each site are interconnected by a common two conductor cable in a unique telemonitoring format. This format allows both control and data information to be received or transmitted at any point on the cable which can be up to 3000 meters total length. The site microprocessor maintains a current data table, detects several faults, drives a printer, and communicates with the central telemonitoring station. The radiation detectors are made with plastic scintillators and photomultiplier tubes operated in a constant current mode with a 4 decade measurement range. The detectors also respond within microseconds to the criticality radiation burst. These characteristics can be tested with an internal light emitting diode either completely with a manual procedure or routinely with a system test initiated by the central monitoring station. Although the system was developed for a criticality alarm which requires reliable and redundant features, the basic techniques are useable for other monitoring and instrumentation applications

Assessment of criticality safety

International Nuclear Information System (INIS)

Lloyd, R.C.; Heaberlin, S.W.; Clayton, E.D.; Carter, R.D.

1979-01-01

A study was made of 100 violations of criticality safety specifications reported over a 10-y period in the operations of fuel reprocessing plants. The seriousness of each rule violation was evaluated by assigning it a severity index value. The underlying causes or reasons, for the violations were identified. A criticality event tree was constructed using the parameters, causes, and reasons found in the analysis of the infractions. The event tree provides a means for visualizing the paths to an accidental criticality. Some 65% of the violations were caused by misinterpretation on the part of the operator, being attributed to a lack of clarity in the specification and insufficient training; 33% were attributed to lack of care, whereas only 2% were caused by mechanical failure. A fault tree was constructed by assembling the events that could contribute to an accident. With suitable data on the probabilities of contributing events, the probability of the accident's occurrence can be forecast. Estimated probabilities for criticality were made, based on the limited data available, that in this case indicate a minimum time span of 244 y of plant operation per accident ranging up to approx. 3000 y subject to the various underlying assumptions made. Some general suggestions for improvement are formulated based on the cases studied. Although conclusions for other plants may differ in detail, the general method of analysis and the fault tree logic should prove applicable. 4 figures, 8 tables

Comparison study of hybrid VS critical systems in point kinetics

International Nuclear Information System (INIS)

Ritter, G.; Tommasi, J.; Slessarev, L.; Salvatores, M.; Mouney, H.; Vergnes, J.

1999-01-01

An essential motivation for hybrid systems is a potentially high level of intrinsic safety against reactivity accidents. In this respect, it is necessary to assess the behaviour of an Accelerator Driven System during a TOP, LOF or TOC accident. A comparison between a critical and sub-critical reactor shows a larger sensitivity for the critical system. The ADS has an unquestionable advantage in case of TOP but a less favourable behaviour as for LOFWS type of accidents. However in the ADS cases, the beam could be easily shut off during the transient. Therefore, a part of the R and D effort should be focused on the monitoring and control of power. (author)

Ergonomic study of biorhythm effect on the 62 occurrence of human errors and accidents in automobile manufacturing industry

Directory of Open Access Journals (Sweden)

2012-03-01

Conclusion: This study showed that the frequency of accidents in critical days and negative section of physical cycle was more than expected. Also the frequency of accidents in critical days and negative section of emotional and intellectual cycle was less than expected. Due to the physical nature of the work activities in the automobile manufacturing industry can be stated that the study showed that in physical work activities, frequency of accidents in critical days and negative section of physical cycle in which the person is not physically ready to do the job was more than expected.

Strategy generator in computerized accident management support system

International Nuclear Information System (INIS)

Sirola, M.

1994-02-01

An increased interest for research in the field of accident management of nuclear power plants can be noted. Several international programmes have been started in order to be able to understand the basic physical and chemical phenomena in accident conditions. A feasibility study has shown that it would be possible to design and develop a computerized support system for plant staff in accident situations. To achieve this goal the Halden Project has initiated a research programme on Computerized Accident Management Support (CAMS project). The aim is to utilize the capabilities of computerized tools to support the plant staff during the various accident stages. The system will include identification of the accident state, assessment of the future development of the accident and planning of accident mitigation strategies. A prototype is developed to support operators and the Technical Support Centre in decision making during serious accidents in nuclear power plants. A rule based system has been built to take care of the strategy generation. This system assists plant personnel in planning control proposals and mitigation strategies from normal operation to severe accident conditions. The idea of a safety objective tree and knowledge from the emergency procedures have been used. Future prediction requires good state identification of the plant status and some knowledge about the history of some critical variables. The information needs to be validated as well. Accurate calculations in simulators and a large database including all important information from the plant will help the strategy planning. (orig.). (40 refs., 20 figs.)

Radioactive release during nuclear accidents in Chernobyl and Fukushima

Science.gov (United States)

Nur Ain Sulaiman, Siti; Mohamed, Faizal; Rahim, Ahmad Nabil Ab

2018-01-01

Nuclear accidents that occurred in Chernobyl and Fukushima have initiated many research interests to understand the cause and mechanism of radioactive release within reactor compound and to the environment. Common types of radionuclide release are the fission products from the irradiated fuel rod itself. In case of nuclear accident, the focus of monitoring will be mostly on the release of noble gases, I-131 and Cs-137. As these are the only accidents have been rated within International Nuclear Events Scale (INES) Level 7, the radioactive release to the environment was one of the critical insights to be monitored. It was estimated that the release of radioactive material to the atmosphere due to Fukushima accident was approximately 10% of the Chernobyl accident. By referring to the previous reports using computational code systems to model the release rate, the release activity of I-131 and Cs-137 in Chernobyl was significantly higher compare to Fukushima. The simulation code also showed that Chernobyl had higher release rate of both radionuclides on the day of accident. Other factors affecting the radioactive release for Fukushima and Chernobyl accidents such as the current reactor technology and safety measures are also compared for discussion.

On Hobbes’s distinction of accidents

Directory of Open Access Journals (Sweden)

Lupoli Agostino

2012-06-01

Full Text Available An interpolation introduced by K. Schuhmann in his critical edition of "De corpore" (chap. VI, § 13 diametrically overturns the meaning of Hobbes’s doctrine of distinction of accidents in comparison with all previous editions. The article focuses on the complexity of this crucial juncture in "De corpore" argument on which depends the interpretation of Hobbes’s whole conception of science. It discusses the reasons pro and contra Schuhmann’s interpolation and concludes against it, because it is not compatible with the rationale underlying the complex architecture of "De corpore", which involves a symmetry between the ‘logical’ distinction of accidents and the ‘metaphysical’ distinction of phantasms.

Determination of beta-ray emitter concentrations in bioassay samples of the victims in JCO criticality accident

International Nuclear Information System (INIS)

Yukawa, Masae; Nishimura, Yoshikazu; Watanabe, Yoshito

2001-01-01

Concentrations of neutron-induced β-ray emitters in the hair, blood, urine and bone of three workers severely exposed to neutrons in JCO criticality accident were measured with a low background β-ray spectrometer (Pico β) and liquid scintillation counter for the purpose of neutron dose estimation. 32 P is generated by the fast neutron of 2.5 MeV and over in sulfur with (n, p) reaction. Since content of sulfur in hair is high as compared with the other human tissues, we tried to estimate fast neutron fluence to the body surface of the victims using concentrations of 32 P and stable sulfur in their hair. The result shows that two workers, who were exposed to the higher neutron radiation than another worker, received higher doses of irradiation to the frontal side of their trunks than to the heads. For a more detailed mapping of neutron fluence in the body, the measurements of 32 P and 45 Ca induced by (n, γ) reaction in bone were carried out. The results show that one worker (worker A) received a higher dose of neutrons at the frontal right side of the trunk, and that the dose decreased with the distance from the central part of the body. The other (worker B) seems to have gotten a higher dose of irradiation in the face, hands and waist. High amount of 32 P was detected in urine of the workers, and the concentration gradient among three workers showed a similar tendency to the estimated neutron dose from 24 Na in blood. Therefore, radioactivity of 32 P in urine could be used for estimating the neutron exposure dose. Moreover, the activity can be easily determined by scintillation counting, and urine is less invading bioassay sample that can be collected by non-medical stuffs. (author)

Criticality safety assessment of a TRIGA reactor spent-fuel pool under accident conditions

International Nuclear Information System (INIS)

Glumac, B.; Ravnik, M.; Logar, M.

1997-01-01

Additional criticality safety analysis of a pool-type storage for TRIGA spent fuel at the Jozef Stefan Institute in Ljubljana, Slovenia, is presented. Previous results have shown that subcriticality is not guaranteed for some postulated accidents (earthquake with subsequent fuel rack disintegration resulting in contact fuel pitch) under the assumption that the fuel rack is loaded with fresh 12 wt% standard fuel. To mitigate this deficiency, a study was done on replacing a certain number of fuel elements in the rack with cadmium-loaded absorber rods. The Monte Carlo computer code MCNP4A with an ENDF/B-V library and detailed three-dimensional geometrical model of the spent-fuel rack was used for this purpose. First, a minimum critical number of fuel elements was determined for contact pitch, and two possible geometries of rack disintegration were considered. Next, it was shown that subcriticality can be ensured when pitch is decreased from a rack design pitch of 8 cm to contact, if a certain number of fuel elements (8 to 20 out of 70) are replaced by absorber rods, which are uniformly mixed into the lattice. To account for the possibility that random mixing of fuel elements and absorber rods can occur during rack disintegration and result in a supercritical configuration, a probabilistic study was made to sample the probability density functions for random absorber rod lattice loadings. Results of the calculations show that reasonably low probabilities for supercriticality can be achieved (down to 10 -6 per severe earthquake, which would result in rack disintegration and subsequent maximum possible pitch decrease) even in the case where fresh 12 wt% standard TRIGA fuel would be stored in the spent-fuel pool

Simulation of severe accident using March-3 computer code

International Nuclear Information System (INIS)

Fernandes, A.; Nakata, H.

1991-01-01

The severe accident sensitivity analysis utilizing the March-3 approximate modelization options has been performed. The reference results against which the present results have been compared were obtained from the best published results for the most representative accident sequences: TMLU, S sub(2)DC sub(r) and S sub(2)DCF sub(r) for the Zion-1 reactor. The results of the present sensitivity analysis revealed the presence of very crude modelizations, in the March-3 program, to represent the critical phenomenologies involved in the severe accident sequences considered, even though large uncertainties must still be taken into account due primarily to the scarcity of the integral benchmark data. (author)

Factors Affecting Road Traffic Accident in Batu Pahat, Johor, Malaysia

Science.gov (United States)

Che-Him, Norziha; Roslan, Rozaini; Saifullah Rusiman, Mohd; Khalid, Kamil; Ghazali Kamardan, M.; Azbi Arobi, Farquis; Mohamad, Nazeera

2018-04-01

A road traffic accident resulted from the combination of factors related to the few components of the system involving environment, roads, road users, vehicles and the interaction between those systems. Road traffic accident (RTA) in Malaysia recorded as the highest fatality rate (per 100,000 population) among the ASEAN countries. In 2016, more than half of million cases accident recorded with more than 7,000 people were killed. Therefore, the RTA is one of the most critical issue in Malaysia even become the worldwide burden to authority. Generally, driving is a complex process which involves movement of a vehicle by either a computer or human controller. However, failure to control and coordinate will contribute to an accident. The objective of this study is to identify the pattern of accident in Johor Malaysia and to examine the relationship between the number of accident and the types of vehicles and roads. The results could help the government to recognise the different patterns, types of vehicles and roads that show major factors in the increasing of road traffic accident in Malaysia.

Nuclear accident: dosimetric and medical aspects

International Nuclear Information System (INIS)

Oliveira, A.R. de.

The conservation aspect of the treatment of patients who received whole-body exposure is presented. Such treatment to be started during the first hours after the accident (prodomal phase), as well as the nonconventional measures to be adopted when the critical phase of acute irradiation syndrome is reached. (E.G.) [pt

[A spatially explicit analysis of traffic accidents involving pedestrians and cyclists in Berlin].

Science.gov (United States)

Lakes, Tobia

2017-12-01

In many German cities and counties, sustainable mobility concepts that strengthen pedestrian and cyclist traffic are promoted. From the perspectives of urban development, traffic planning and public healthcare, a spatially differentiated analysis of traffic accident data is decisive. 1) The identification of spatial and temporal patterns of the distribution of accidents involving cyclists and pedestrians, 2) the identification of hotspots and exploration of possible underlying causes and 3) the critical discussion of benefits and challenges of the results and the derivation of conclusions. Spatio-temporal distributions of data from accident statistics in Berlin involving pedestrians and cyclists from 2011 to 2015 were analysed with geographic information systems (GIS). While the total number of accidents remains relatively stable for pedestrian and cyclist accidents, the spatial distribution analysis shows, however, that there are significant spatial clusters (hotspots) of traffic accidents with a strong concentration in the inner city area. In a critical discussion, the benefits of geographic concepts are identified, such as spatially explicit health data (in this case traffic accident data), the importance of the integration of other data sources for the evaluation of the health impact of areas (traffic accident statistics of the police), and the possibilities and limitations of spatial-temporal data analysis (spatial point-density analyses) for the derivation of decision-supported recommendations and for the evaluation of policy measures of health prevention and of health-relevant urban development.

Criticality accident dosimetry systems: an international intercomparison at the SILENE reactor in 2002.

Science.gov (United States)

Médioni, R; Asselineau, B; Verrey, B; Trompier, F; Itié, C; Texier, C; Muller, H; Pelcot, G; Clairand, I; Jacquet, X; Pochat, J L

2004-01-01

In criticality accident dosimetry and more generally for high dose measurements, special techniques are used to measure separately the gamma ray and neutron components of the dose. To improve these techniques and to check their dosimetry systems (physical and/or biological), a total of 60 laboratories from 29 countries (America, Europe, Asia) participated in an international intercomparaison, which took place in France from 9 to 21 June 2002, at the SILENE reactor in Valduc and at a pure gamma source in Fontenay-aux-Roses. This intercomparison was jointly organised by the IRSN and the CEA with the help of the NEA/OCDE and was partly supported by the European Communities. This paper describes the aim of this intercomparison, the techniques used by the participants and the two radiation sources and their characteristics. The experimental arrangements of the dosemeters for the irradiations in free air or on phantoms are given. Then the dosimetric quantities measured and reported by the participants are summarised, analysed and compared with the reference values. The present paper concerns only the physical dosimetry and essentially experiments performed on the SILENE facility. The results obtained with the biological dosimetry are published in two other papers of this issue.

Solutions to criticality problems in a plutonium extraction plant

International Nuclear Information System (INIS)

Jouannaud, C.; Rodier, J.; Fruchard, Y.; Peyresblanques, H.; Papault, C.; Tabardel-Brian, R.

1968-08-01

There are two aspects to nuclear criticality safety: prevention of criticality and protection against the consequences of a possible accident: this report considers these two aspects in the case of the Marcoule Plutonium Extraction Plant. After briefly recalling the various techniques used for avoiding criticality (mass, geometry, concentration, poisoning), the authors describe their application in the plant and show in particular that, a rational use of a favorable geometry is a factor both for security and from an economic point of view. The authors then describe the inside organisation which makes it possible to obtain the necessary intrinsic safety standard right from the advance project stage, and to control the workshop safety during the operation of the plant. The second part of the report deals with the system of protection against the consequences of a possible accident: definition of a typical accident, fixing of the boundaries of a critical zone, safety alarm device, individual and collective dosimetry, evacuation plan and safety instructions. (authors) [fr

Safety analysis of the Los Alamos critical experiments facility

International Nuclear Information System (INIS)

Paxton, H.C.

1975-10-01

The safety of Pajarito Site critical assembly operations depends upon protection built into the facility, upon knowledgeable personnel, and upon good practice as defined by operating procedures and experimental plans. Distance, supplemented by shielding in some cases, would protect personnel against an extreme accident generating 10 19 fissions. During the facility's 28-year history, the direct cost of criticality accidents has translated to a risk of less than $200 per year

Accident analysis and DOE criteria

International Nuclear Information System (INIS)

Graf, J.M.; Elder, J.C.

1982-01-01

In analyzing the radiological consequences of major accidents at DOE facilities one finds that many facilities fall so far below the limits of DOE Order 6430 that compliance is easily demonstrated by simple analysis. For those cases where the amount of radioactive material and the dispersive energy available are enough for accident consequences to approach the limits, the models and assumptions used become critical. In some cases the models themselves are the difference between meeting the criteria or not meeting them. Further, in one case, we found that not only did the selection of models determine compliance but the selection of applicable criteria from different chapters of Order 6430 also made the difference. DOE has recognized the problem of different criteria in different chapters applying to one facility, and has proceeded to make changes for the sake of consistency. We have proposed to outline the specific steps needed in an accident analysis and suggest appropriate models, parameters, and assumptions. As a result we feed DOE siting and design criteria will be more fairly and consistently applied

Safety of Ikata Nuclear Power Station from the accident of Three Mile Island

International Nuclear Information System (INIS)

Nonaka, Hiroshi

1979-01-01

The leak of radioactive substances occurred on March 28, 1979, in the No. 2 plant of Three Mile Island Nuclear Power Station, and this accident must be put to use to prevent similar accidents and to secure safety hereafter in the nuclear power stations being operated in Japan. In the TMI accident, too many problems concerning the operation management seemed to exist in a series of events. In this paper, a few matters related to the TMI accident among the aspects of the operation management in Ikata Nuclear Power Station are reported. As the problems of operation management, it is considered that the operation of the TMI plant was continued as the exit valve of auxiliary feed line was closed, that it took long time to close the root valve for a pressurizer relief valve manually, and that the ECCS was stopped manually. In TMI, the abnormal phenomenon of losing main feed water has occurred 6 times since the attainment of criticality in March, 1978, and the opening and sticking of pressurizer relief valves occurred at least twice in about 150 times of their actuation in the nuclear reactors designed by Babcock and Wilcox Co. In Ikata Nuclear Power Station, these problems are detected early and the suitable measures are taken immediately, therefore it never happens to continue the operation as the problems are left as they are. It is not conceivable that similar troubles occur many times. (Kako, I.)

A New Method to Detect and Correct the Critical Errors and Determine the Software-Reliability in Critical Software-System

International Nuclear Information System (INIS)

Krini, Ossmane; Börcsök, Josef

2012-01-01

In order to use electronic systems comprising of software and hardware components in safety related and high safety related applications, it is necessary to meet the Marginal risk numbers required by standards and legislative provisions. Existing processes and mathematical models are used to verify the risk numbers. On the hardware side, various accepted mathematical models, processes, and methods exist to provide the required proof. To this day, however, there are no closed models or mathematical procedures known that allow for a dependable prediction of software reliability. This work presents a method that makes a prognosis on the residual critical error number in software. Conventional models lack this ability and right now, there are no methods that forecast critical errors. The new method will show that an estimate of the residual error number of critical errors in software systems is possible by using a combination of prediction models, a ratio of critical errors, and the total error number. Subsequently, the critical expected value-function at any point in time can be derived from the new solution method, provided the detection rate has been calculated using an appropriate estimation method. Also, the presented method makes it possible to make an estimate on the critical failure rate. The approach is modelled on a real process and therefore describes two essential processes - detection and correction process.

Analysis of severe core damage accident progression for the heavy water reactor

International Nuclear Information System (INIS)

Tong Lili; Yuan Kai; Yuan Jingtian; Cao Xuewu

2010-01-01

In this study, the severe accident progression analysis of generic Canadian deuterium uranium reactor 6 was preliminarily provided using an integrated severe accident analysis code. The selected accident sequences were multiple steam generator tube rupture and large break loss-of-coolant accidents because these led to severe core damage with an assumed unavailability for several critical safety systems. The progressions of severe accident included a set of failed safety systems normally operated at full power, and initiative events led to primary heat transport system inventory blow-down or boil off. The core heat-up and melting, steam generator response,fuel channel and calandria vessel failure were analyzed. The results showed that the progression of a severe core damage accident induced by steam generator tube rupture or large break loss-of-coolant accidents in a CANDU reactor was slow due to heat sinks in the calandria vessel and vault. (authors)

Critical management system for nuclear fuels

International Nuclear Information System (INIS)

Tai, Ichiro; Seki, Eiji.

1981-01-01

Purpose: To enable to provide display for the scale of accidents and critical state by detecting gamma-rays issued from nuclear fuels by gamma-ray level indicators to obtain outputs in proportion to the input level of the gamma-rays based on the detected pulse signals. Constitution: The gamma-ray level indicators comprises a plastic scintillator that emits light upon input of gamma-rays and a photomultiplier that amplifies weak fluorescence obtained from the scintillator. The photomultiplier is applied with a high voltage from a power source. A pre-amplifier amplifies pulse signals corresponding to individual gamma-rays at a high amplification factor and send them to a pulse counter circuit if the detected signal level from the gamma-ray level indicators is low, or amplifies the pulse detection signals at a low amplification factor and sends them to a voltage pulse averaging circuit if the detection signal level is high. A signal procession circuit selects the output from the pulse counter circuit or the voltage pulse averaging circuit. Thus, the system has a linear characteristic over a wide range equivalent to a wide range of incident gamma-rays. (Horiuchi, T.)

Quick evaluation of the neutron dose following a criticality accident by measurement of sodium 24 activity

International Nuclear Information System (INIS)

Tabardel, R.; Ricourt, A.; Parmentier, N.

1984-07-01

In order to quickly sort out the irradiated individuals following a criticality accident, the neutron dose can be evaluated quickly by measuring the sodium-24 activity induced in the human body. The report supplies the information necessary for this evaluation from the response of various detectors of current use in radiation protection. The first part describes the method of evaluation of sodium-24 activity (A) given by the reading (M) of each instrument. The second part describes the method of kerma evaluation from the measured sodium-24 activity. The third part is an experimental application of the method of kerma evaluation from the sodium-24 activity measured in a phantom irradiated in the SILENE reactor flux. The results given by radiation protection instruments are in good agreement with the calculated values for a front exposure and demonstrate the usefulness of measuring the induced sodium-24 activity by radiation protection instruments of current use [fr

Investigating of the effect of Biorhythm on work-related Accidents

Directory of Open Access Journals (Sweden)

F. Arab

2014-07-01

Conclusion: Findings of this research showed that bad and critical days of individuals’ biorhythms cycle influence the occurrence of accidents. Therefore, by training and increasing the knowledge of workers regarding biological cycle and its effects on mental, emotional and physical status, each person effects can make some changes to theire work plans during days that they do not feel well, physically or mentally, in order to prevent the likely accidents.

Accidents involving specialized aircraft in agriculture aerial spraying

Directory of Open Access Journals (Sweden)

Marcelo Boamorte Ravelli

Full Text Available ABSTRACT: The great challenge for the practice of agricultural aviation has been to avoid accidents. Although, there are technological progress and high resources for safety, accidents continue to occur. The objective of this research was to analyze the influence and occurrence of factors in agricultural aviation accidents in Brazil recently. Based on research and technical - scientific papers written by researchers and aviation authorities, recommendations directed towards reducing the risks associated with this aircraft modality are assessed. The main factors responsible for accidents are normally operational errors and maneuvers that cause flight collisions, engine failures and altitude loss. Professional awareness and qualification converge towards the success of the agricultural pilot in the detection of inherent dangers or occasional in the various systems involved.

Overview of the radiological accidents in the world, updated December 1989

Energy Technology Data Exchange (ETDEWEB)

Nenot, J.C. (CEA Centre d' Etudes Nucleaires de Fontenay-aux-Roses, 92 (France). Dept. de Protection Sanitaire)

1990-06-01

This outline historical review discusses radiological accidents of two categories: those involving large groups of the population with relatively low doses, or a few individuals with high doses resulting in acute health effects. Comments on the following accidents are made: (a) the Marshallese population and the Japanese Fisherman, Pacific Ocean 1954 (b) South East Urals USSR 1957 (c) Juarez, Mexico 1983/84 (d) Chernobyl 1986 (e) Goiania, Brazil 1987. Registration of accidents resulting in high doses to few individuals is also discussed:-criticality accidents, those resulting in high whole-body doses from sealed sources, nuclear power reactor incidents leading to acute doses among workers, those resulting in localized radiation injury and those resulting in severe internal exposure. (UK).

Differences of detection efficiency among several nasal swab samples simulated for nuclear emergency accident

International Nuclear Information System (INIS)

Fukutsu, Kumiko; Yamada, Yuji; Kurihara, Osamu; Akashi, Makoto; Momose, Takumaro; Miyabe, Kenjiro

2008-01-01

At nuclear emergency accident such as inhalation intake of alpha nuclide, an indispensable nasal swab method has not been used for the precise internal dose estimation. One of the reasons is uncertainty in its radiation measurement, so that precise measurement with alpha spectrometry was examined for filter samples simulating nasal swab. It was confirmed that the alpha spectrometry made possible the distinction between solution and particulate in addition to the nuclide identification. The alpha activity in swab sample was precisely evaluated only when the detection efficiency was determined considering the self-absorption with filter fibers. Another big problem of wiping efficiency in nasal swabbing is still remain, but this study certainly raised the usefulness of the nasal swab method for rapid response in emergency. (author)

Monte Carlo dose reconstruction in case of a radiological accident: application to the accident in Chile in December 2005; Reconstitution de dose par calcul Monte Carlo en cas d'accident radiologique: application a l'accident du Chili de decembre 2005

Energy Technology Data Exchange (ETDEWEB)

Huet, C.; Clairand, I.; Trompier, F.; Bottollier-Depois, J.F. [Institut de Radioprotection et de Surete Nucleaire (IRSN), Dir. de la Radioprotection de l' Homme, 92 - Fontenay aux Roses (France); Bey, E. [Hopital d' Instruction des Armees Percy, 92 - Clamart (France)

2007-10-15

Following a radiological accident caused by a gamma-graphy source in Chile in December 2005 involving one victim, I.R.S.N. was contacted to perform the dosimetric reconstruction of the accident using numerical simulation. Tools developed in the laboratory, associating anthropomorphic mathematic or voxel phantoms with the Monte Carlo calculation code m.c.n.p.x., were used in order to determine the dose distribution on the left buttock and absorbed doses to critical organs. The dosimetric mapping show that the absorbed at the skin surface is very high (1900 Gy) but drops rapidly at deep. At a depth of 5 cm, it is 20 Gy. Calculations performed with a mathematical phantom indicate that average doses to the critical organs are relatively low. Moreover, possible bone marrow sites for puncture are identified. Based on the dosimetric mapping, an excision measuring 5 cm in depth by 10 cm in diameter was performed on the left buttock of the victim. (authors)

Postulated accidents

International Nuclear Information System (INIS)

Ullrich, W.

1980-01-01

This lecture on 'Postulated Accidents' is the first of a series of lectures on the dynamic and transient behaviour of nuclear power plants, especially pressurized water reactors. The main points covered will be: Reactivity Accidents, Transients (Intact Loop) and Loss of Cooland Accidents (LOCA) including small leak. This lecture will discuss the accident analysis in general, the definition of the various operational phases, the accident classification, and, as an example, an accident sequence analysis on the basis of 'Postulated Accidents'. (orig./RW)

Accident sequence analysis of human-computer interface design

International Nuclear Information System (INIS)

Fan, C.-F.; Chen, W.-H.

2000-01-01

It is important to predict potential accident sequences of human-computer interaction in a safety-critical computing system so that vulnerable points can be disclosed and removed. We address this issue by proposing a Multi-Context human-computer interaction Model along with its analysis techniques, an Augmented Fault Tree Analysis, and a Concurrent Event Tree Analysis. The proposed augmented fault tree can identify the potential weak points in software design that may induce unintended software functions or erroneous human procedures. The concurrent event tree can enumerate possible accident sequences due to these weak points

Novel biodosimetry methods applied to victims of the Goiania accident

International Nuclear Information System (INIS)

Straume, T.; Langlois, R.G.; Lucas, J.; Jensen, R.H.; Bigbee, W.L.; Ramalho, A.T.; Brandao-Mello, C.E.

1991-01-01

Two biodosimetric methods under development at the Lawrence Livermore National Laboratory were applied to five persons accidentally exposed to a 137Cs source in Goiania, Brazil. The methods used were somatic null mutations at the glycophorin A locus detected as missing proteins on the surface of blood erythrocytes and chromosome translocations in blood lymphocytes detected using fluorescence in-situ hybridization. Biodosimetric results obtained approximately 1 y after the accident using these new and largely unvalidated methods are in general agreement with results obtained immediately after the accident using dicentric chromosome aberrations. Additional follow-up of Goiania accident victims will (1) help provide the information needed to validate these new methods for use in biodosimetry and (2) provide independent estimates of dose

Chernobyl accident: Assessing the data

Energy Technology Data Exchange (ETDEWEB)

Soerensen, B

1986-01-01

Data presented in the official Soviet report to the IAEA on the Chernobyl reactor accident are critically assessed. Special attention is given to the derivation of release fractions from fallout measurements, a procedure which is demonstrated to involve large elements of uncertainty. Further comments relate to estimates of plume rise and deposition velocity. A comparison is made with the predictions of previously published theoretical reactor safety studies.

New approach to managing nuclear criticality risk at Nuclear Fuel Services, Inc

International Nuclear Information System (INIS)

Green, R.; Droke, R.; Paine, D.

1992-01-01

The negative aspects of having a nuclear criticality accident at a fuel fabrication facility have substantially increased in recent years. Although ensuring that the facility is designed and operating in a critically safe manner is a high management priority, practices of managing the risk of a criticality accident have not significantly changed. The method of evaluating risk based on quantitative analysis can enable management to adapt to the increased consequences of a nuclear criticality accident. Additional controls may be placed on high-risk areas within a facility to ensure safe operation of the plant. Areas where controls are in place that impede the productivity of the facility and have negligible impact on criticality safety may be removed or replaced. Management can also streamline the safety analysis efforts applied to facility upgrades by demonstrating that proposed design changes do not compromise criticality safety. Future expansion of quantitative analysis techniques will also allow risk-based management decisions on industrial, radiological, and environmental safety

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)

Accident management

International Nuclear Information System (INIS)

Lutz, R.J.; Monty, B.S.; Liparulo, N.J.; Desaedeleer, G.

1989-01-01

The foundation of the framework for a Severe Accident Management Program is the contained in the Probabilistic Safety Study (PSS) or the Individual Plant Evaluations (IPE) for a specific plant. The development of a Severe Accident Management Program at a plant is based on the use of the information, in conjunction with other applicable information. A Severe Accident Management Program must address both accident prevention and accident mitigation. The overall Severe Accident Management framework must address these two facets, as a living program in terms of gathering the evaluating information, the readiness to respond to an event. Significant international experience in the development of severe accident management programs exist which should provide some direction for the development of Severe Accident Management in the U.S. This paper reports that the two most important elements of a Severe Accident Management Program are the Emergency Consultation process and the standards for measuring the effectiveness of individual Severe Accident Management Programs at utilities

Analysis of traffic accidents in Romania, 2009.

Science.gov (United States)

Călinoiu, Geovana; Minca, Dana Galieta; Furtunescu, Florentina Ligia

2012-01-01

This paper aimed to underline the main consequences of traffic accidents in Romania 2009 and their associated causes or circumstances. We identified some problematic geographic areas, some critical months or moments of the day and also the most frequent causes; all these should become targets for the future planning. The current analysis provides some priority criteria for public health interventions. So, the future national road safety strategy should be in line with the EU objectives, but also with the national priorities. Romania is far away from the average EU target for 2010 of halving the death by traffic accidents registered in 2001. To describe the circumstances and the consequences related to traffic accidents registered in Romania, for the year 2009. An ecological study was conducted. The traffic accidents circumstances were analyzed in terms of magnitude, geographic space, time and cause. The consequences were analyzed as affected people and damaged cars. A total of 28,627 traffic accidents were registered in Romania during the year 2009. 2,796 people were killed and 27,968 were hospitalized and 42,443 cars were damaged. 3 of 4 accidents were caused by violations on behalf of the car drivers. Most common violations in car drivers were excess of speed and priority violations (52.4%). Among the pedestrians, 7 of 10 accidents were caused by illegal crossing. A higher number of accidents occurred during the summer months and during the evening hours (from 5.00 pm till 8.00 pm). The traffic accidents represent a real public health problem in Romania and a serious burden for the health system. The gap between Romania and the other EU member states needs to be diminished in the next decade. In this purpose, the future national road safety strategy should be in line with the EU objectives, but also with the national priorities. Research is needed to understand the causes and the socio-economical impact of traffic accidents and to define appropriate national

Accidents in nuclear facilities: classification, incidence and impact

International Nuclear Information System (INIS)

Galicia A, J.; Paredes G, L. C.

2012-10-01

A general analysis of the 146 accidents reported officially in nuclear facilities from 1945 to 2012 is presented, among them some took place in: power or research nuclear reactors, critical and subcritical nuclear assemblies, handling of nuclear materials inside laboratories belonging to institutes or universities, in radiochemistry industrial plants and nuclear fuel factories. In form graph the incidence of these accidents is illustrated classified for; category, decades, geographical localization, country classification before the OECD, failure type, and the immediate or later victims. On the other hand, the main learned lessons of the nuclear accidents of Three Mile Island, Chernobyl and Fukushima are stood out, among those that highlight; the human factors, the necessity of designs more innovative and major technology for the operation, control and surveillance of the nuclear facilities, to increase the criterions of nuclear, radiological and physics safety applied to these facilities, the necessity to carry out probabilistic analysis of safety more detailed for cases of not very probable accidents and their impact, to revalue the selection criterions of the sites for nuclear locations, the methodology of post-accident sites recovery and major instrumentation for parameters evaluation and the radiological monitoring among others. (Author)

Data mining and visualization of the Alabama accident database

Science.gov (United States)

2000-08-01

The Alabama Department of Public Safety has developed and maintains a centralized database that contain traffic accident data collected from crash report completed by local police officers and state troopers. The Critical Analysis Reporting Environme...

PWR pressure vessel integrity during overcooling accidents

International Nuclear Information System (INIS)

Cheverton, R.D.

1981-01-01

Pressurized water reactors are susceptible to certain types of hypothetical accidents that under some circumstances, including operation of the reactor beyond a critical time in its life, could result in failure of the pressure vessel as a result of propagation of crack-like defects in the vessel wall. The accidents of concern are those that result in thermal shock to the vessel while the vessel is subjected to internal pressure. Such accidents, referred to as pressurized thermal shock or overcooling accidents (OCA), include a steamline break, small-break LOCA, turbine trip followed by stuck-open bypass valves, the 1978 Rancho Seco and the TMI accidents and many other postulated and actual accidents. The source of cold water for the thermal shock is either emergency core coolant or the normal primary-system coolant. ORNL performed fracture-mechanics calculations for a steamline break in 1978 and for a turbine-trip case in 1980 and concluded on the basis of the results that many more such calculations would be required. To meet the expected demand in a realistic way a computer code, OCA-I, was developed that accepts primary-system temperature and pressure transients as input and then performs one-dimensional thermal and stress analyses for the wall and a corresponding fracture-mechanics analysis for a long axial flaw. The code is briefly described, and its use in both generic and specific plant analyses is discussed

French safety and criticality testing programmes

International Nuclear Information System (INIS)

Barbry, F.; Leclerc, J.; Manaranche, J.C.; Maubert, L.

1982-01-01

This article underlines the need to include experimental safety-criticality programmes in the French nuclear effort. The means and methods used at the Section of Experimental Nuclear Safety and Criticality Research, attached to the CEA Valduc Centre, are described. Three experimental programmes are presented: safety-criticality of the PWR fuel cycle, neutron poisoning of plutonium solutions by gadolinium and safety-criticality of slightly enriched and slightly moderated uranium oxide. Criticality accidents studies in solution are then described [fr

Case examples of chemical plant accidents. What we learn from them?

International Nuclear Information System (INIS)

Nakamura, Masayoshi

2009-01-01

Lessons learned from the JCO Nuclear Criticality Accident of 30 September 1999 in a uranium conversion test plant in Tokai-mura, Japan, are reviewed by referring some pertinent matters from the official report of this accident to remind of the universal characteristics among possible accidents of chemical plants. The paper discusses the responsibility of the establishment or institution to the demand alternation or request change from the client, how to respond to the proposal arising from the factory floor, and the safety control system of every-day maintenance of the factory which are important to prevent accidents in chemical plants. After explaining a background leading to the JCO accident, the author summarizes the lessons as follows: (1) changeable control system, (2) perfect provision of the manual considering the actual condition, and (3) clarification of the roles each played by the managers and the workers are most necessary and important. (S. Ohno)

Compendium on neutron spectra in criticality accident dosimetry

International Nuclear Information System (INIS)

Ing, H.

1978-01-01

Graphical and tabulated neutron spectra are presented: from selected critical assemblies; from critical solutions; of fission neutrons through shielding; of H 2 O-moderated fission neutrons through shielding; of D 2 O-moderated fission neutrons through shielding; of fission neutrons reflected from various materials; from the D(T, 4 He)n reaction (''14 MeV'' neutrons) through shielding and of ''14 MeV'' neutrons reflected from various materials

Consequences of the Chernobyl accident in Lithuania

International Nuclear Information System (INIS)

Mastauskas, A.; Nedvecktaite, T.; Filistovic, V.

1997-01-01

After the Chernobyl accident of 26 April, 1986, population dose assessment favours the view that the radiation risk of population effected by the early fallout would be different from that in regions contaminated later. Taking into account the short half-time of the most important radioactive iodine isotopes, thyroid disorders would be expected mainly to follow the early fallout distribution. At the time of accident at Unite 4 of the Chernobyl NPP, surface winds were from the Southeast. The initial explosions and heat carried volatile radioactive materials to the 1,5 km height, from where they were transported over the Western part of Belarus, Southern and Western part of Lithuania toward Scandinavian countries. Thus the volatile radioiodine and some other radionuclides were detected in Lithuania on the very first days after the accident. The main task of the work - to conduct short Half-time radioiodine and long half-time radiocesium dose assessment of Lithuanian inhabitants a result of the early Chernobyl accident fallout

Investigation Effect of Biorhythm on Work-Related Accidents in The Metal Industry (A Short Report

Directory of Open Access Journals (Sweden)

Ehsanollah Habibi

2016-07-01

Full Text Available Biorhythm is one of the newest subjects in the field of cognition of mental ergonomics which can be very effective in reduction of work-related accidents or mistakes with no apparent reason. With evaluating Biorhythm individuals can intervention action to reduce job accidents carried out. Thus, the aim of this study was to determine the relationship Biorhythm and work-related accidents in the metal industry. This research is a cross-sectional and analytical-descriptive in the metal industrial Isfahan city of 120 work-related accidents during 2015. The required information was collected from available documents in HSE unit of the company biorhythm charts were drawn based on a date of accidents and participants birthdays, using natural Biorhythm Software V3.02 Conduct. Finally، the data were analyzed using spss version 20 and descriptive statistics.This study showed that the frequency of accidents in critical days and negative section of physical cycle was more than expected. Also the frequency of accidents in critical days and negative section of emotional and intellectual cycles was less than expected. Most type of injury, including cuts to 35.8 percent and the lowest type of injury was torsion with 5 percent. Most limb injury, hands and fingers with 51.7 percent and the lowest limb injury were back at 2.5 percent. Accidents outbreak in physical cycles was 38.3 percent. These 120 accidents in additionally were causing 120 loss of working days in effect accident. Most percent of loss of working days were for 20 to 30 days with of 39.2 percent. Most percent of loss of working days were for 20 to 30 days with of 39.2 percent. Due to the physical nature of the work activities in the metal industry can be stated that the study showed that in physical work activities, frequency of accidents in critical days and negative section of physical cycle in which the person is not physically ready to do the job was more than expected. Therefore, by training

An international co-ordinated research programme on nuclear accident dosimetry

International Nuclear Information System (INIS)

Flakus, F.N.

1977-01-01

Where fissile materials are being processed in quantities exceeding the minimum critical amounts, a radiation risk to workers arises from the possibility of criticality excursions. Despite the fact that techniques for preventing the occurende of such accidental excursions have reached very high standards it is generally agreed that the availability of suitable nuclear accident dosimetry (NAD) systems is very important. Following the recommendations of an Advisory Group meeting on NAD, the IAEA had established in 1969 an international coordinated research programme on NAD systems and elaborating standarized systems. A large number of research groups from 14 Member States throughout the world participated in this co-ordinated work. Since 1970 four international multilaboratory intercomparison experiments on NAD have been organized and the response of a variety of dosimeters examined in different neutron spectra under simulated accident conditions at Valduc (France), Oak Ridge (USA), Vinca (Yugoslavia) and Harwell (UK). The results achieved in these intercomparison studies show that NAD systems have been substantially improved and that several systems are available now in a number of laboratories throughout the world that perform within the criteria laid down by the initiating advisory group in 1969. A compendium of neutron leakage spectra has also been elaborated for facilitating the determination of dose from readings of detectors exposed to various neutron fields in criticality accidents

Accident management insights after the Fukushima Daiichi NPP accident

International Nuclear Information System (INIS)

Degueldre, Didier; Viktorov, Alexandre; Tuomainen, Minna; Ducamp, Francois; Chevalier, Sophie; Guigueno, Yves; Tasset, Daniel; Heinrich, Marcus; Schneider, Matthias; Funahashi, Toshihiro; Hotta, Akitoshi; Kajimoto, Mitsuhiro; Chung, Dae-Wook; Kuriene, Laima; Kozlova, Nadezhda; Zivko, Tomi; Aleza, Santiago; Jones, John; McHale, Jack; Nieh, Ho; Pascal, Ghislain; ); Nakoski, John; Neretin, Victor; Nezuka, Takayoshi; )

2014-01-01

The Fukushima Daiichi nuclear power plant (NPP) accident, that took place on 11 March 2011, initiated a significant number of activities at the national and international levels to reassess the safety of existing NPPs, evaluate the sufficiency of technical means and administrative measures available for emergency response, and develop recommendations for increasing the robustness of NPPs to withstand extreme external events and beyond design basis accidents. The OECD Nuclear Energy Agency (NEA) is working closely with its member and partner countries to examine the causes of the accident and to identify lessons learnt with a view to the appropriate follow-up actions to be taken by the nuclear safety community. Accident management is a priority area of work for the NEA to address lessons being learnt from the accident at the Fukushima Daiichi NPP following the recommendations of Committee on Nuclear Regulatory Activities (CNRA), Committee on the Safety of Nuclear Installations (CSNI), and Committee on Radiation Protection and Public Health (CRPPH). Considering the importance of these issues, the CNRA authorised the formation of a task group on accident management (TGAM) in June 2012 to review the regulatory framework for accident management following the Fukushima Daiichi NPP accident. The task group was requested to assess the NEA member countries needs and challenges in light of the accident from a regulatory point of view. The general objectives of the TGAM review were to consider: - enhancements of on-site accident management procedures and guidelines based on lessons learnt from the Fukushima Daiichi NPP accident; - decision-making and guiding principles in emergency situations; - guidance for instrumentation, equipment and supplies for addressing long-term aspects of accident management; - guidance and implementation when taking extreme measures for accident management. The report is built on the existing bases for capabilities to respond to design basis

Identification of the operating crew's information needs for accident management

International Nuclear Information System (INIS)

Nelson, W.R.; Hanson, D.J.; Ward, L.W.; Solberg, D.E.

1988-01-01

While it would be very difficult to predetermine all of the actions required to mitigate the consequences of every potential severe accident for a nuclear power plant, development of additional guidance and training could improve the likelihood that the operating crew would implement effective sever-accident management measures. The US Nuclear Regulatory Commission (NRC) is conducting an Accident Management Research Program that emphasizes the application of severe-accident research results to enhance the capability of the plant operating crew to effectively manage severe accidents. One element of this program includes identification of the information needed by the operating crew in severe-accident situations. This paper discusses a method developed for identifying these information needs and its application. The methodology has been applied to a generic reactor design representing a PWR with a large dry containment. The information needs were identified by systematically determining what information is needed to assess the health of the critical functions, identify the presence of challenges, select strategies, and assess the effectiveness of these strategies. This method allows the systematic identification of information needs for a broad range of severe-accident scenarios and can be validated by exercising the functional models for any specific event sequence

Modelling and forecasting occupational accidents of different severity levels in Spain

International Nuclear Information System (INIS)

Carmen Carnero, Maria; Jose Pedregal, Diego

2010-01-01

The control of accidents at the work place is a critical issue all over the world. The consequences of occupational accidents in terms of costs for the company in which the accidents take place is only one minor matter, being the social impact and the loss of human life the most controversial effects of this important problem. The methods used to forecast future evolution of accidents are often limited to trend estimations and projections, being the scientific literature on this topic rather scarce. This paper aims at showing and predicting the evolution of Spanish occupational accidents of different levels of severity, allowing the evaluation of the influence that preventive actions carried out by public administrations or private companies may have over the number of occupational accidents. Though some contributions may be found on this topic for Spain, this paper is the first contribution that forecast occupational accidents for different levels of severity using Multivariate Unobserved Components models developed in a State Space framework extended to deal with the irregular sampling interval of the data. Data from 1998 to 2009 have been used to test the efficacy of the forecasting system.

Helicopter emergency medical services response to equestrian accidents.

Science.gov (United States)

Lyon, Richard M; Macauley, Ben; Richardson, Sarah; de Coverly, Richard; Russell, Malcolm

2015-04-01

Horse riding is a common leisure activity associated with a significant rate of injury. Helicopter emergency medical services (HEMS) may be called to equestrian accidents. Accurate HEMS tasking is important to ensure appropriate use of this valuable medical resource. We sought to review HEMS response to equestrian accidents and identify factors associated with the need for HEMS intervention or transport of the patient to a major trauma centre. Retrospective case review of all missions flown by Kent, Surrey & Sussex Air Ambulance Trust over a 1-year period (1 July 2011 to 1 July 2012). All missions were screened for accidents involving a horse. Call details, patient demographics, suspected injuries, clinical interventions and patient disposition were all analysed. In the 12-month data collection period there were 47 equestrian accidents, representing ∼3% of the total annual missions. Of the 42 cases HEMS attended, one patient was pronounced life extinct at the scene. In 15 (36%) cases the patient was airlifted to hospital. In four (10%) cases, the patient underwent prehospital anaesthesia. There were no specific predictors of HEMS intervention. Admission to a major trauma centre was associated with the rider not wearing a helmet, a fall onto their head or the horse falling onto the rider. Equestrian accidents represent a significant proportion of HEMS missions. The majority of patients injured in equestrian accidents do not require HEMS intervention, however, a small proportion have life-threatening injuries, requiring immediate critical intervention. Further research is warranted, particularly regarding HEMS dispatch, to further improve accuracy of tasking to equestrian accidents.

Development of Parameter Network for Accident Management Applications

Energy Technology Data Exchange (ETDEWEB)

Pak, Sukyoung; Ahemd, Rizwan; Heo, Gyunyoung [Kyung Hee Univ., Yongin (Korea, Republic of); Kim, Jung Taek; Park, Soo Yong; Ahn, Kwang Il [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-10-15

When a severe accident happens, it is hard to obtain the necessary information to understand of internal status because of the failure or damage of instrumentation and control systems. We learned the lessons from Fukushima accident that internal instrumentation system should be secured and must have ability to react in serious conditions. While there might be a number of methods to reinforce the integrity of instrumentation systems, we focused on the use of redundant behavior of plant parameters without additional hardware installation. Specifically, the objective of this study is to estimate the replaced value which is able to identify internal status by using set of available signals when it is impossible to use instrumentation information in a severe accident, which is the continuation of the paper which was submitted at the last KNS meeting. The concept of the VPN was suggested to improve the quality of parameters particularly to be logged during severe accidents in NPPs using a software based approach, and quantize the importance of each parameter for further maintenance. In the future, we will continue to perform the same analysis to other accident scenarios and extend the spectrum of initial conditions so that we are able to get more sets of VPNs and ANN models to predict the behavior of accident scenarios. The suggested method has the uncertainty underlain in the analysis code for severe accidents. However, In case of failure to the safety critical instrumentation, the information from the VPN would be available to carry out safety management operation.

Unavoidable Accident

OpenAIRE

Grady, Mark F.

2009-01-01

In negligence law, "unavoidable accident" is the risk that remains when an actor has used due care. The counterpart of unavoidable accident is "negligent harm." Negligence law makes parties immune for unavoidable accident even when they have used less than due care. Courts have developed a number of methods by which they "sort" accidents to unavoidable accident or to negligent harm, holding parties liable only for the latter. These sorting techniques are interesting in their own right and als...

Status of criticality safety research at NUCEF

Energy Technology Data Exchange (ETDEWEB)

Nakajima, Ken [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1998-03-01

Two critical facilities, named STACY (Static Experiment Critical Facility) and TRACY (Transient Experiment Critical Facility), at the Nuclear Fuel Cycle Safety Engineering Research Facility (NUCEF) started their hot operations in 1995. Since then, basic experimental data for criticality safety research have been accumulated using STACY, and supercritical experiments for the study of criticality accident in a reprocessing plant have been performed using TRACY. In this paper, the outline of those critical facilities and the main results of TRACY experiments are presented. (author)

Traffic Accidents Involving Cyclists Identifying Causal Factors Using Questionnaire Survey, Traffic Accident Data, and Real-World Observation.

Science.gov (United States)

Oikawa, Shoko; Hirose, Toshiya; Aomura, Shigeru; Matsui, Yasuhiro

2016-11-01

The purpose of this study is to clarify the mechanism of traffic accidents involving cyclists. The focus is on the characteristics of cyclist accidents and scenarios, because the number of traffic accidents involving cyclists in Tokyo is the highest in Japan. First, dangerous situations in traffic incidents were investigated by collecting data from 304 cyclists in one city in Tokyo using a questionnaire survey. The survey indicated that cyclists used their bicycles generally while commuting to work or school in the morning. Second, the study investigated the characteristics of 250 accident situations involving cyclists that happened in the city using real-world bicycle accident data. The results revealed that the traffic accidents occurred at intersections of local streets, where cyclists collided most often with vehicles during commute time in the morning. Third, cyclists' behavior was observed at a local street intersection in the morning in the city using video pictures. In one hour during the morning commute period, 250 bicycles passed through the intersection. The results indicated that one of the reasons for traffic accidents involving cyclists might be the combined effect of low visibility, caused by the presence of box-like building structures close to the intersections, and the cyclists' behavior in terms of their velocity and no confirming safety. It was observed that, on average, bicycle velocity was 3.1 m/s at the initial line of an intersection. The findings from this study could be useful in developing new technologies to improve cyclist safety, such as alert devices for cyclists and vehicle drivers, wireless communication systems between cyclists and vehicle drivers, or advanced vehicles with bicycle detection and collision mitigation systems.

Criticality Safety in the Handling of Fissile Material. Specific Safety Guide

Energy Technology Data Exchange (ETDEWEB)

NONE

2014-05-15

This Safety Guide provides guidance and recommendations on how to meet the relevant requirements for ensuring subcriticality when dealing with fissile material and for planning the response to criticality accidents. The guidance and recommendations are applicable to both regulatory bodies and operating organizations. The objectives of criticality safety are to prevent a self-sustained nuclear chain reaction and to minimize the consequences of this if it were to occur. The Safety Guide makes recommendations on how to ensure subcriticality in systems involving fissile materials during normal operation, anticipated operational occurrences, and, in the case of accident conditions, within design basis accidents, from initial design through commissioning, operation, and decommissioning and disposal.

Lessons learned from radiological accidents at medical exposures in radiotherapy

International Nuclear Information System (INIS)

Fagundes, J.S.; Ferreira, A.F.; Lima, C.M.A.; Silva, F.C.A. da

2017-01-01

An exposure is considered accidental in radiotherapy when there is a substantial deviation in the prescription of treatment. In this work, an analysis of published radiological accidents, both in Brazil and internationally, was performed during medical exposures in radiotherapy treatments, removing the main lessons learned. Of the research carried out, we highlight Brazil with four radiological accidents and one death in the period between 2011 and 2014; the United States of America with 169 accidents with two deaths from 2000 to 2010 and France from 2001 to 2014 had 569 deaths without patients. Lessons learned have been described, for example, that maintenance personnel training should specify limitations or restrictions on the handling or adjustment of critical parts on the accelerator. It is recommended to apply the 10 main lessons learned due to radiological accidents during medical exposures in radiotherapy treatments to avoid future events

Radiological accident and incident in Thailand: Lesson to be learned

International Nuclear Information System (INIS)

Ya-anant, N.; Tiyapun, K.; Saiyut, K.

2011-01-01

Radioactive materials in Thailand have been used in medicine, research and industry for more than 50 y. Several radiological accident and incidents happened in the past 10 y. A serious one was the radiological accident that occurred in Samut Prakan (Thailand) in 2000. The serious radiological accident occurred when the 60 Co head was partially dismantled, taken from that storage to sell as scrap metal. Three victims died and 10 people received high dose from the source. The lesson learned from the radiological accident in Samut Prakan was to improve in many subjects, such as efficiency in Ministerial Regulations and Atomic Energy Act, emergency response and etc. In addition to the serious accident, there are also some small incidents that occurred, such as detection of contaminated scrap metals from the re-cycling of scrap metals from steel factories. Therefore, the radiation protection infrastructure was established after the accident. Laws and regulations of radiation safety and the relevant regulatory procedures must be revised. (authors)

Annual meeting on nuclear technology 1982. Technical meeting: Possibilities and effects of serious reactor accidents

International Nuclear Information System (INIS)

1982-01-01

A critical examination of the forecast of a design basis accident, the view of the Sandia National Laboratory on the probability of a steam explosion after a core meltdown accident is comparison with WASH-1400, the possibilities of interactions with the containment structure and fission product release, as well as the influences for the assessment of risk in Germany taken from the analysis of core meltdown accidents are dealt with in these papers. (DG) [de

The accidents due to ionizing radiations - the situation on a half century

International Nuclear Information System (INIS)

2007-02-01

This report takes stock updated in 2006, serious accidents occurred in the four sectors in civil, industrial, medical and military. Its goal is to provide an explanatory and critical review of the most representative accident that caused serious harm to victims. The report analyses for each accident, and whenever reliable data exist, the reasons for its occurrence, consequences for victims and possibly to the environment, remedial actions that have been made and medical treatments when they were innovative. Using a combination of accidents with common features, the report offers key lessons to be learned from these tragic events. This report is intended for practitioners of radiation protection in general and does not target particular experts in any technical or medical specialty. (N.C.)

Domino effect in chemical accidents: main features and accident sequences

OpenAIRE

Casal Fàbrega, Joaquim; Darbra Roman, Rosa Maria

2010-01-01

The main features of domino accidents in process/storage plants and in the transportation of hazardous materials were studied through an analysis of 225 accidents involving this effect. Data on these accidents, which occurred after 1961, were taken from several sources. Aspects analyzed included the accident scenario, the type of accident, the materials involved, the causes and consequences and the most common accident sequences. The analysis showed that the most frequent causes a...

Stress in accident and post-accident management at Chernobyl

International Nuclear Information System (INIS)

Girard, P.; Dubreuil, G.H.

1996-01-01

The effects of the Chernobyl nuclear accident on the psychology of the affected population have been much discussed. The psychological dimension has been advanced as a factor explaining the emergence, from 1990 onwards, of a post-accident crisis in the main CIS countries affected. This article presents the conclusions of a series of European studies, which focused on the consequences of the Chernobyl accident. These studies show that the psychological and social effects associated with the post-accident situation arise from the interdependency of a number of complex factors exerting a deleterious effect on the population. We shall first attempt to characterise the stress phenomena observed among the population affected by the accident. Secondly, we will be presenting an anlysis of the various factors that have contributed to the emerging psychological and social features of population reaction to the accident and in post-accident phases, while not neglecting the effects of the pre-accident situation on the target population. Thirdly, we shall devote some initial consideration to the conditions that might be conducive to better management of post-accident stress. In conclusion, we shall emphasise the need to restore confidence among the population generally. (Author)

The role of OSHA violations in serious workplace accidents.

Science.gov (United States)

Mendeloff, J

1984-05-01

California accident investigations for 1976 show that violations of the Occupational Safety and Health Administration's safety standards were a contributing factor in 13% to 19% of the 645 deaths reported to the workers' compensation program during that year. However, a panel of safety engineers judged that only about 50% of these violations could have been detected if an inspector had visited the day before the accident. These findings indicate that the potential gains from stronger enforcement of current standards are limited but not insignificant. The likelihood that a violation contributed to a serious accident varied considerably among accident types, industries, and size classes of plants. These findings can be used to increase the efficiency and effectiveness of the OSHA program by means of better targeting of inspections and accident investigations, more intelligent assessment of which violations should be penalized most heavily, and the provision of information to employers and workers about which violations are most consequential.

Development of A Methodology for Assessing Various Accident Management Strategies Using Decision Tree Models

Energy Technology Data Exchange (ETDEWEB)

Kim, Nam Yeong; Kim, Jin Tae; Jae, Moo Sung [Hanyang University, Seoul (Korea, Republic of); Jerng, Dong Wook [Chung-Ang University, Seoul (Korea, Republic of)

2016-05-15

The purpose of ASP (Accident Sequence Precursor) analysis is to evaluate operational accidents in full power and low power operation by using PRA (Probabilistic Risk Assessment) technologies. The awareness of the importance of ASP analysis has been on rise. The methodology for ASP analysis has been developed in Korea, KINS (Korea Institute of Nuclear Safety) has managed KINS-ASP program since it was developed. In this study, we applied ASP analysis into operational accidents in full power and low power operation to quantify CCDP (Conditional Core Damage Probability). To reflect these 2 cases into PRA model, we modified fault trees and event trees of the existing PRA model. Also, we suggest the ASP regulatory system in the conclusion. In this study, we reviewed previous studies for ASP analysis. Based on it, we applied it into operational accidents in full power and low power operation. CCDP of these 2 cases are 1.195E-06 and 2.261E-03. Unlike other countries, there is no regulatory basis of ASP analysis in Korea. ASP analysis could detect the risk by assessing the existing operational accidents. ASP analysis can improve the safety of nuclear power plant by detecting, reviewing the operational accidents, and finally removing potential risk. Operator have to notify regulatory institute of operational accident before operator takes recovery work for the accident. After follow-up accident, they have to check precursors in data base to find similar accident.

Radiological accidents: methodologies of radio nuclides dis incorporation

International Nuclear Information System (INIS)

Jimenez F, E. A.; Paredes G, L.; Cortes, A.

2014-08-01

Derived of the radioactive or nuclear material management, exists the risk that accidents can happen where people cases are presented with internal radioactive contamination, who will receive specialized medical care to accelerate the radioactive dis incorporation with the purpose of diminishing the absorbed dose and the associate biological effects. In this work treatments of radioactive dis incorporation were identified, in function of the radionuclide, radiation type, radioactive half life, biological half life, critical organ, ingestion duct and patient type. The factor time is decisive for the effectiveness of the selected treatment in the blockade stage (before the accident) or dis incorporation (after the accident); this factor is related with the radioactive and biological half lives. So to achieve dis incorporation efficiencies of more to 70%, the patient clinical treatment will begin before the first third of the biological half life of the radionuclide that generated the internal contamination. (Author)

Community response against the nuclear accident. Confusion in Sweden after the Chernobyl nuclear accident and its features

International Nuclear Information System (INIS)

Sato, Yoshihiro

2014-01-01

The Chernobyl nuclear accident, which occurred in April 1986, became popular in Sweden after two days, and Sweden was hit by a big mess immediately after that. This paper introduces various actions taken in Sweden at that time. The authors analyzed the situation based on the following materials to tell the situation at that time: (1) materials summarized by researchers upon request of the administrative organs of the country, (2) two diaries that were written by Sven Aner, who was a former reporter of a major daily newspaper published after the accident and an activist of antinuclear groups, and Sven Lofvegerg, who handled the accident as a technical officer at Radiation Protection Agency, and (3) newspaper articles at that time. The situations that was revealed after the accident were summarized from the following viewpoints: (1) governmental remarks toward safety standards and effects on residents, and the anxiety of residents, (2) grazing ban on livestock as an important industry and its lifting, (3) correspondence of antinuclear activists, (4) anxiety against the effects of radiation on humans, and counseling on the safety addressed to the Headquarters for Disaster Control, (5) roles of regional radio stations, (6) defects of bureaucracy, (7) criticism against the actions of the Headquarters for Disaster Control, and (8) influence of extreme experts. (A.O.)

Nuclear accident dosimetry. Revision of emergency data sheets

International Nuclear Information System (INIS)

Delafield, H.J.

1976-09-01

The Emergency Data Sheets on Nuclear Accident Dosimetry have been revealed following the publication of a three part manual on this subject (Delafield, Dennis and Gibson, AERE-R 7485/6/7, 1973). This memo provides an explanation of the action levels adopted for the initial segregation of irradiated persons following a criticality accident, by monitoring the activity of indium foils contained in personnel dosimeters and the induced body sodium activity. The data sheets are given as an Appendix. They provide basic information on; the segregation of irradiated persons, the estimation of radiation exposure, and the assessment of personnel γ-ray and neutron doses. (author)

Study of a criticality accident involving fuel rods and water outside a power reactor; Etude d'un accident de criticite mettant en presence des crayons combustibles et de l'eau hors reacteur de puissance

Energy Technology Data Exchange (ETDEWEB)

Beloeil, L

2000-05-30

It is possible to imagine highly unlikely but numerous accidental situations where fuel rods come into contact with water under conditions close to atmospheric values. This work is devoted to modelling and simulation of first instants of the power excursion that may result from such configurations. We show that void effect is a preponderant feedback for most severe accidents. The formation of a vapour film around the rods is put forward and confirmed with the help of experimental transients using electrical heating. We propose then a vapour/liquid flow model able to reproduce void fraction evolution. The vapour film is treated as a compressible medium. Conservation balance equations are solved on a moving mesh with a two-dimensional scheme and boundary conditions taking notice of interfacial phenomena and axial escape possibility. Movements of the liquid phase are modelled through a non-stationary integral equation and a dissipative term suited to the particular geometry of this flow. The penetration of energy into the liquid is also calculated. Thus, the coupling of aerodynamic and hydrodynamic modules gives results in excellent agreement with experiments. Next, neutronic phenomena into the fuel pellet, their feedback effects and the distribution of power through the rod are numerically translated. For each developed module, validation tests are provided. Then, it is possible to simulate the first seconds of the whole criticality accident. Even if this calculation tool is only a way of study as a first approach, performed simulations are proving coherent with reported data on recorded accidents. (author)

Nuclear criticality safety: 2-day training course

International Nuclear Information System (INIS)

Schlesser, J.A.

1992-11-01

This compilation of notes is presented as a source reference for the criticality safety course. At the completion of this training course, the attendee will: (1) be able to define terms commonly used in nuclear criticality safety; (2) be able to appreciate the fundamentals of nuclear criticality safety; (3) be able to identify factors which affect nuclear criticality safety; (4) be able to identify examples of criticality controls as used at Los Alamos; (5) be able to identify examples of circumstances present during criticality accidents; (6) have participated in conducting two critical experiments

Safety apparatus for serious radioactive accidents (1962); Materiel d'intervention en cas d'accident radioactif grave (1962)

Energy Technology Data Exchange (ETDEWEB)

Estournel, R; Rodier, J [Commissariat a l' Energie Atomique, Centre de Production de Plutonium, Marcoule (France). Centre d' Etudes Nucleaires

1962-07-01

In the case of a serious radioactive accident, radioactive dust and gases may be released into the atmosphere. It is therefore necessary to be able to evaluate rapidly the importance of the risk to the surrounding population, and to be able to ensure, even in the event of an evacuation of the Centre, the continuation of the radioactivity analyses and the decontamination of the personnel. For this, the Anti-radiation Protection Service at Marcoule has organised mobile detection teams and designed a mobile laboratory and a mobile shower-unit. After describing the duty of the mobile teams, the report gives a description of the apparatus which would be used at the Marcoule Centre in the case of a serious radioactive accident. The method of using this apparatus is given. (authors) [French] Lors d'un accident radioactif grave, des poussieres et des gaz radioactifs peuvent etre relaches dans l'atmosphere. II est alors indispensable d'evaluer rapidement l'importance du risque couru par les populations environnantes, et de pouvoir assurer, meme dans le cas de l'evacuation du Centre, la poursuite des analyses radioactives et la decontamination du personnel. Pour cela, le Service de Protection contre les Radiations du Centre de Marcoule a mis sur pied des equipes mobiles de detection et realise une semi-remorque laboratoire ainsi qu'une semi-remorque douches. Apres avoir defini la mission des equipes mobiles, le rapport donne la description du materiel d'intervention qui serait mis en oeuvre par le Centre de Marcoule dans le cas d'un accident radioactif grave. Il precis le mode d'utilisation de ce materiel. (auteurs)

Road Traffic Accident Analysis of Ajmer City Using Remote Sensing and GIS Technology

Science.gov (United States)

Bhalla, P.; Tripathi, S.; Palria, S.

2014-12-01

With advancement in technology, new and sophisticated models of vehicle are available and their numbers are increasing day by day. A traffic accident has multi-facet characteristics associated with it. In India 93% of crashes occur due to Human induced factor (wholly or partly). For proper traffic accident analysis use of GIS technology has become an inevitable tool. The traditional accident database is a summary spreadsheet format using codes and mileposts to denote location, type and severity of accidents. Geo-referenced accident database is location-referenced. It incorporates a GIS graphical interface with the accident information to allow for query searches on various accident attributes. Ajmer city, headquarter of Ajmer district, Rajasthan has been selected as the study area. According to Police records, 1531 accidents occur during 2009-2013. Maximum accident occurs in 2009 and the maximum death in 2013. Cars, jeeps, auto, pickup and tempo are mostly responsible for accidents and that the occurrence of accidents is mostly concentrated between 4PM to 10PM. GIS has proved to be a good tool for analyzing multifaceted nature of accidents. While road safety is a critical issue, yet it is handled in an adhoc manner. This Study is a demonstration of application of GIS for developing an efficient database on road accidents taking Ajmer City as a study. If such type of database is developed for other cities, a proper analysis of accidents can be undertaken and suitable management strategies for traffic regulation can be successfully proposed.

A second simulated criticality accident dosimetry experiment

CERN Document Server

Adams, N

1973-01-01

This experiment was undertaken to facilitate training in criticality dose assessment by UKAEA and BNFL establishments with potential criticality hazards. Personal dosemeters, coins, samples of hair, etc. supplied by the seven participating establishments were attached to a man-phantom filled with a solution of sodium nitrate (simulating 'body-sodium'), and exposed to a burst of radiation from the AWRE pulsed reactor VIPER. The neutron and photon doses were each several hundred rads. Participants made two sets of dose assessments. The first, made solely from the evidence of their routine dosemeters the activation of body-sodium and standard monitoring data, simulated the initial dose assessment that would be made before the circumstances of a real incident were established. The second was made when the position and orientation of the phantom relative to the reactor and the shielding (20 cm of copper) between the reactor core and the phantom were disclosed. Neutron and photon dose assessments for comparison wit...

Characteristics of Hydrogen Monitoring Systems for Severe Accident Management at a Nuclear Power Plant

Science.gov (United States)

Petrosyan, V. G.; Yeghoyan, E. A.; Grigoryan, A. D.; Petrosyan, A. P.; Movsisyan, M. R.

2018-02-01

One of the main objectives of severe accident management at a nuclear power plant is to protect the integrity of the containment, for which the most serious threat is possible ignition of the generated hydrogen. There should be a monitoring system providing information support of NPP personnel, ensuring data on the current state of a containment gaseous environment and trends in its composition changes. Monitoring systems' requisite characteristics definition issues are considered by the example of a particular power unit. Major characteristics important for proper information support are discussed. Some features of progression of severe accident scenarios at considered power unit are described and a possible influence of the hydrogen concentration monitoring system performance on the information support reliability in a severe accident is analyzed. The analysis results show that the following technical characteristics of the combustible gas monitoring systems are important for the proper information support of NPP personnel in the event of a severe accident at a nuclear power plant: measured parameters, measuring ranges and errors, update rate, minimum detectable concentration of combustible gas, monitoring reference points, environmental qualification parameters of the system components. For NPP power units with WWER-440/270 (230) type reactors, which have a relatively small containment volume, the update period for measurement results is a critical characteristic of the containment combustible gas monitoring system, and the choice of monitoring reference points should be focused not so much on the definition of places of possible hydrogen pockets but rather on the definition of places of a possible combustible mixture formation. It may be necessary for the above-mentioned power units to include in the emergency operating procedures measures aimed at a timely heat removal reduction from the containment environment if there are signs of a severe accident phase

Critical assessment of efficiency of immediate intervention

International Nuclear Information System (INIS)

Romanenko, A.E.

1996-01-01

Critical analysis is given in this report on measures conducted after the Chernobyl NPP accident of provision of health care of inhabitants of suffered areas. Among shortages of the first stage of the accident it is pointed out: lack of modem instruments, dispersion of establishmental forces and means and dyscoordination of actions of different establishments having taken part in the accident elimination, excessive confidentiality, insufficient level of knowledge in the field of radiation medicine, low efficiency of radio protection measures, in particular, iodine prophylaxis. Thyroid irradiation doses were not taken into account in full measure for decision making about evacuation

XENON-133 IN CALIFORNIA, NEVADA, AND UTAH FROM THE CHERNOBYL ACCIDENT (JOURNAL VERSION)

Science.gov (United States)

The accident at the Chernobyl nuclear reactor in the USSR introduced numerous radioactive nuclides into the atmosphere, including the noble gas xenon-133. EPA's Environmental Monitoring Systems Laboratory, Las Vegas, NV, detected xenon-133 from the Chernobyl accident in air sampl...

A Ubiquitous and Low-Cost Solution for Movement Monitoring and Accident Detection Based on Sensor Fusion

Directory of Open Access Journals (Sweden)

Filipe Felisberto

2014-05-01

Full Text Available The low average birth rate in developed countries and the increase in life expectancy have lead society to face for the first time an ageing situation. This situation associated with the World’s economic crisis (which started in 2008 forces the need of equating better and more efficient ways of providing more quality of life for the elderly. In this context, the solution presented in this work proposes to tackle the problem of monitoring the elderly in a way that is not restrictive for the life of the monitored, avoiding the need for premature nursing home admissions. To this end, the system uses the fusion of sensory data provided by a network of wireless sensors placed on the periphery of the user. Our approach was also designed with a low-cost deployment in mind, so that the target group may be as wide as possible. Regarding the detection of long-term problems, the tests conducted showed that the precision of the system in identifying and discerning body postures and body movements allows for a valid monitorization and rehabilitation of the user. Moreover, concerning the detection of accidents, while the proposed solution presented a near 100% precision at detecting normal falls, the detection of more complex falls (i.e., hampered falls will require further study.

MDCT findings in sports and recreational accidents.

Science.gov (United States)

Bensch, Frank V; Koivikko, Mika P; Koskinen, Seppo K

2011-12-01

Sports and recreational accidents involving critical areas of the body occur commonly in the general population. Reports on their demographics and recommendations for screening procedures are, however, few. To assess injuries of the craniofacial area, spine, and torso resulting from sports and recreational accidents with multidetector computed tomography (MDCT) as primary imaging method in a Level I trauma center. All emergency room CT requests over a time span of 105 months were reviewed retrospectively for trauma mechanism and injury. Patients were identified using an electronic picture archiving and communications system (PACS), and MDCT studies interpreted by two radiologists independently. Of a total of 5898 patients, 492 patients (301 boys/men, 191 girls/women, age range 2-76 years, mean 33.5 years, median 29.5 years) with sports or recreational accidents emerged. A total of 102 traumatic findings were diagnosed, thereof 72 (71%) serious. The three most commonly encountered serious injuries were intracranial injury, fractures of facial bones, and vertebral injuries. The three most common injury mechanisms were bicycling, horseback riding, and team ball sports. Patients from recreational activities were on average significantly younger (29.2 years) than those from sports accidents (36.9 years; P accidents presented with an overall incidence of 21%, of which 71% are serious. The most common mechanisms of injury were bicycling, horseback riding, and team ball sports. The largest incidence of serious injury involved bicycling. Because of the high probability of a serious injury and the high energies that are often involved in these accidents, we recommend ruling out of internal injury by MDCT as the primary imaging modality.

Instrumentation Performance during the TMI-2 Accident

International Nuclear Information System (INIS)

Rempe, Joy L.; Knudson, Darrell L.

2013-06-01

The accident at the Three Mile Island Unit 2 (TMI- 2) reactor provided a unique opportunity to evaluate sensors exposed to severe accident conditions. Conditions associated with the release of coolant and the hydrogen burn that occurred during this 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 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 new effort focused upon a set of sensors that provided critical data to TMI-2 operators for assessing the condition of the plant and the effects of mitigating actions taken by these operators. In addition, the effort considered sensors providing data required for subsequent accident simulations. Over 100 references related to instrumentation performance and post-accident evaluations of TMI-2 sensors and measurements were reviewed. Insights gained from this review are summarized within this paper. As noted within this paper, several techniques were invoked in the TMI-2 post-accident program to evaluate sensor survivability status and data qualification, 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 but more easily removed from the TMI-2 plant for evaluations. Conclusions from this review provide important insights related to sensor survivability and enhancement options for improving sensor performance. In addition, this paper provides recommendations related to sensor survivability and the data evaluation process that could be implemented in upcoming Fukushima Daiichi recovery efforts. (authors)

Development of posture-specific computational phantoms using motion capture technology and application to radiation dose-reconstruction for the 1999 Tokai-Mura nuclear criticality accident

International Nuclear Information System (INIS)

Vazquez, Justin A; Caracappa, Peter F; Xu, X George

2014-01-01

The majority of existing computational phantoms are designed to represent workers in typical standing anatomical postures with fixed arm and leg positions. However, workers found in accident-related scenarios often assume varied postures. This paper describes the development and application of two phantoms with adjusted postures specified by data acquired from a motion capture system to simulate unique human postures found in a 1999 criticality accident that took place at a JCO facility in Tokai-Mura, Japan. In the course of this accident, two workers were fatally exposed to extremely high levels of radiation. Implementation of the emergent techniques discussed produced more accurate and more detailed dose estimates for the two workers than were reported in previous studies. A total-body dose of 6.43 and 26.38 Gy was estimated for the two workers, who assumed a crouching and a standing posture, respectively. Additionally, organ-specific dose estimates were determined, including a 7.93 Gy dose to the thyroid and 6.11 Gy dose to the stomach for the crouching worker and a 41.71 Gy dose to the liver and a 37.26 Gy dose to the stomach for the standing worker. Implications for the medical prognosis of the workers are discussed, and the results of this study were found to correlate better with the patient outcome than previous estimates, suggesting potential future applications of such methods for improved epidemiological studies involving next-generation computational phantom tools. (paper)

Self-reported accidents

DEFF Research Database (Denmark)

Møller, Katrine Meltofte; Andersen, Camilla Sloth

2016-01-01

The main idea behind the self-reporting of accidents is to ask people about their traffic accidents and gain knowledge on these accidents without relying on the official records kept by police and/or hospitals.......The main idea behind the self-reporting of accidents is to ask people about their traffic accidents and gain knowledge on these accidents without relying on the official records kept by police and/or hospitals....

Accident analysis device for nuclear power plants

International Nuclear Information System (INIS)

Ito, Masayuki.

1982-01-01

Purpose: To enable rapid recognition of and countermeasure required for accidents upon scram, by identifying the first contact point of causes for resulting the scram and displaying the contact point of causes. Constitution: When a scram signal is inputted by way of process input device, the time of the input is determined by a timer and the contact point of causes generated just before is taken as the point whose changes occurred prior to but most closely to the generation of the signal while referring to the data memory section for the time of change of the contact point of the cause, and sent to the accident analyzing display. The accident analyzing display extracts, based on the contact point of cause, a list for the forecast accidents corresponding thereto from the data memory section and also extracts the list for the corresponding confirmation items of the accident detection and displays them together with the system from which the scram signal has been generated, the time of generation, the name of the contact point of causes operated at first, and the value of the state quantity contained in the data memory section for the store of contact point of cause at the change. (Kawakami, Y.)

A methodology for radiological accidents analysis in industrial gamma radiography

International Nuclear Information System (INIS)

Silva, F.C.A. da.

1990-01-01

A critical review of 34 published severe radiological accidents in industrial gamma radiography, that happened in 15 countries, from 1960 to 1988, was performed. The most frequent causes, consequences and dose estimation methods were analysed, aiming to stablish better procedures of radiation safety and accidents analysis. The objective of this work is to elaborate a radiological accidents analysis methodology in industrial gamma radiography. The suggested methodology will enable professionals to determine the true causes of the event and to estimate the dose with a good certainty. The technical analytical tree, recommended by International Atomic Energy Agency to perform radiation protection and nuclear safety programs, was adopted in the elaboration of the suggested methodology. The viability of the use of the Electron Gamma Shower 4 Computer Code System to calculate the absorbed dose in radiological accidents in industrial gamma radiography, mainly at sup(192)Ir radioactive source handling situations was also studied. (author)

Aspects of water and air ingress accidents in HTRs

International Nuclear Information System (INIS)

Wolters, J.

1981-01-01

The work has contributed towards improving the understanding of the processes taking place during water and air ingress accidents. The favourable design features of the THTR limit the pressure build-up in the primary circuit to values below critical values in water ingress accidents even when the source of water is not identified and shut-off. A pressure reduction by safety valves is in this case not necessary so that the accident consequences remain confined in the primary circuit. The expected air ingress rates following a depressurization accident through an opening in the top head of the PCRV are extremely small in the case of complete integration of the primary circuit in the PCRV. The chemical processes in the primary circuit remain so limited that no danger for the fuel elements and the containment exists. The often feared ''graphite fire'' can be excluded even in the case when the circulators of the after-heat removal systems take in a high percentage of containment atmosphere. The core is cooled down safely

A System Supporting the Analysis of Motorway Traffic Accidents

Directory of Open Access Journals (Sweden)

Davide Anghinolfi

2015-12-01

Full Text Available This work presents a business intelligence tool for monitoring traffic accidents on motorways and supporting decisions relevant to road safety. The system manages information on road characteristics, traffic accidents and traffic volumes and produces reports for monitoring the evolution of key performance indicators for road safety, supporting decisions on actions for risk mitigation and safety improvements for road users. The paper illustrates the different types of analyses performed by the system. Pattern based analysis is used to evaluate safety performance indicators for the road sections matching defined patterns. Two different road segmentation algorithms, used to identify the most critical road sections according to various severity indicators, are presented and discussed. Differential analysis compares the value of selected severity indicators before and after the implementation of an intervention on a road. Finally, a graphical user interface allows the accident locations to be visualized and accidents with specific characteristics to be highlighted. The system was evaluated on the data collected between 2009 and 2011 for the A15 motorway in Italy, connecting Parma to La Spezia.

Nuclear criticality safety aspects of emergency response at the Los Alamos National Laboratory

International Nuclear Information System (INIS)

Baker, J.S.

2003-01-01

Emergency response at Los Alamos National Laboratory (LANL) is handled through a graded approach depending on the specific emergency situation . LANL maintains a comprehensive capability to respond to events ranging from minor facility events (alerts) through major community events (general emergencies), including criticality accidents . Criticality safety and emergency response apply to all activities involving significant quantities of fissile material at LANL, primarily at Technical Area 18 (TA-18, the Los Alamos Critical Experiments Facility) and Technical Area 55 (TA-55, the Plutonium Facility). This discussion focuses on response to a criticality accident at TA-55; the approach at TA-18 is comparable .

Nuclear criticality safety: 2-day training course

International Nuclear Information System (INIS)

Schlesser, J.A.

1997-02-01

This compilation of notes is presented as a source reference for the criticality safety course. At the completion of this training course, the attendee will: be able to define terms commonly used in nuclear criticality safety; be able to appreciate the fundamentals of nuclear criticality safety; be able to identify factors which affect nuclear criticality safety; be able to identify examples of criticality controls as used as Los Alamos; be able to identify examples of circumstances present during criticality accidents; have participated in conducting two critical experiments; be asked to complete a critique of the nuclear criticality safety training course

Nuclear criticality safety: 2-day training course

Energy Technology Data Exchange (ETDEWEB)

Schlesser, J.A. [ed.] [comp.

1997-02-01

This compilation of notes is presented as a source reference for the criticality safety course. At the completion of this training course, the attendee will: be able to define terms commonly used in nuclear criticality safety; be able to appreciate the fundamentals of nuclear criticality safety; be able to identify factors which affect nuclear criticality safety; be able to identify examples of criticality controls as used as Los Alamos; be able to identify examples of circumstances present during criticality accidents; have participated in conducting two critical experiments; be asked to complete a critique of the nuclear criticality safety training course.

Review of Ontario Hydro Pickering 'A' and Bruce 'A' nuclear generating stations' accident analyses

International Nuclear Information System (INIS)

Serdula, K.J.

1988-01-01

Deterministic safety analysis for the Pickering 'A' and Bruce 'A' nuclear generating stations were reviewed. The methodology used in the evaluation and assessment was based on the concept of 'N' critical parameters defining an N-dimensional safety parameter space. The reviewed accident analyses were evaluated and assessed based on their demonstrated safety coverage for credible values and trajectories of the critical parameters within this N-dimensional safety parameter space. The reported assessment did not consider probability of occurrence of event. The reviewed analyses were extensive for potential occurrence of accidents under normal steady-state operating conditions. These analyses demonstrated an adequate assurance of safety for the analyzed conditions. However, even for these reactor conditions, items have been identified for consideration of review and/or further study, which would provide a greater assurance of safety in the event of an accident. Accident analyses based on a plant in a normal transient operating state or in an off-normal condition but within the allowable operating envelope are not as extensive. Improvements in demonstrations and/or justifications of safety upon potential occurrence of accidents would provide further assurance of adequacy of safety under these conditions. Some events under these conditions have not been analyzed because of their judged low probability; however, accident analyses in this area should be considered. Recommendations are presented relating to these items; it is also recommended that further study is needed of the Pickering 'A' special safety systems

The Chernobyl reactor accident and the aquatic environment of the UK: a fisheries viewpoint

International Nuclear Information System (INIS)

Mitchell, N.T.; Camplin, W.C.; Leonard, D.R.P.

1986-01-01

The monitoring programme undertaken by the Directorate throughout the UK following the Chernobyl reactor accident is described. The results of sampling and analysis of fish, shellfish, seaweed and other materials are discussed. Chernobyl fallout was readily detected in all sectors of the aquatic environment, particularly during May when the highest concentrations were observed. An assessment of the radiological impact of the fallout shows that freshwater fish were the most important source of individual (critical group) exposure though, based on cautious assumptions, the effective dose equivalent is around 1 mSv in a year. The collective effective dose equivalent commitment from Chernobyl due to aquatic ingestion pathways, predominantly marine fish, is estimated to be 30 man Sv. (author)

Domino effect in chemical accidents: main features and accident sequences.

Science.gov (United States)

Darbra, R M; Palacios, Adriana; Casal, Joaquim

2010-11-15

The main features of domino accidents in process/storage plants and in the transportation of hazardous materials were studied through an analysis of 225 accidents involving this effect. Data on these accidents, which occurred after 1961, were taken from several sources. Aspects analyzed included the accident scenario, the type of accident, the materials involved, the causes and consequences and the most common accident sequences. The analysis showed that the most frequent causes are external events (31%) and mechanical failure (29%). Storage areas (35%) and process plants (28%) are by far the most common settings for domino accidents. Eighty-nine per cent of the accidents involved flammable materials, the most frequent of which was LPG. The domino effect sequences were analyzed using relative probability event trees. The most frequent sequences were explosion→fire (27.6%), fire→explosion (27.5%) and fire→fire (17.8%). Copyright © 2010 Elsevier B.V. All rights reserved.

POST CRITICAL HEAT TRANSFER AND FUEL CLADDING OXIDATION

Directory of Open Access Journals (Sweden)

Vojtěch Caha

2016-12-01

Full Text Available The knowledge of heat transfer coefficient in the post critical heat flux region in nuclear reactor safety is very important. Although the nuclear reactors normally operate at conditions where critical heat flux (CHF is not reached, accidents where dryout occur are possible. Most serious postulated accidents are a loss of coolant accident or reactivity initiated accident which can lead to CHF or post CHF conditions and possible disruption of core integrity. Moreover, this is also influenced by an oxide layer on the cladding surface. The paper deals with the study of mathematical models and correlations used for heat transfer calculation, especially in post dryout region, and fuel cladding oxidation kinetics of currently operated nuclear reactors. The study is focused on increasing of accuracy and reliability of safety limit calculations (e.g. DNBR or fuel cladding temperature. The paper presents coupled code which was developed for the solution of forced convection flow in heated channel and oxidation of fuel cladding. The code is capable of calculating temperature distribution in the coolant, cladding and fuel and also the thickness of an oxide layer.

Severe accident management. Optimized guidelines and strategies

International Nuclear Information System (INIS)

Braun, Matthias; Löffler, Micha; Plank, Hermann; Asse, Dietmar; Dimmelmeier, Harald

2014-01-01

the accident progression in near future, to identify the currently most critical tasks as well as upcoming tasks, and to qualify the emergency response team to make informed decisions for the severe accident mitigation based on state-of-the-art knowledge. In this paper, this severe accident management concept is introduced and explained. It is also shown that AREVA is able to apply this methodology to other (including non-OEM) plant types, thus providing a comprehensive safety analysis of the existing plant state with already available safety systems and instrumentation. In addition, the possible need and potential for hardware refitting can be assessed as well. Finally, the severe accident management procedures are then established or updated accordingly. (author)

An integrated graphic–taxonomic–associative approach to analyze human factors in aviation accidents

Directory of Open Access Journals (Sweden)

Gong Lei

2014-04-01

Full Text Available Human factors are critical causes of modern aviation accidents. However, existing accident analysis methods encounter limitations in addressing aviation human factors, especially in complex accident scenarios. The existing graphic approaches are effective for describing accident mechanisms within various categories of human factors, but cannot simultaneously describe inadequate human–aircraft–environment interactions and organizational deficiencies effectively, and highly depend on analysts’ skills and experiences. Moreover, the existing methods do not emphasize latent unsafe factors outside accidents. This paper focuses on the above three limitations and proposes an integrated graphic–taxonomic–associative approach. A new graphic model named accident tree (AcciTree, with a two-mode structure and a reaction-based concept, is developed for accident modeling and safety defense identification. The AcciTree model is then integrated with the well-established human factors analysis and classification system (HFACS to enhance both reliability of the graphic part and logicality of the taxonomic part for improving completeness of analysis. An associative hazard analysis technique is further put forward to extend analysis to factors outside accidents, to form extended safety requirements for proactive accident prevention. Two crash examples, a research flight demonstrator by our team and an industrial unmanned aircraft, illustrate that the integrated approach is effective for identifying more unsafe factors and safety requirements.

Surveillance of Strontium-90 in Foods after the Fukushima Daiichi Nuclear Power Plant Accident.

Science.gov (United States)

Nabeshi, Hiromi; Tsutsumi, Tomoaki; Uekusa, Yoshinori; Hachisuka, Akiko; Matsuda, Rieko; Teshima, Reiko

2015-01-01

As a result of the Fukushima Daiichi nuclear power plant (NPP) accident, various radionuclides were released into the environment. In this study, we surveyed strontium-90 ((90)Sr) concentrations in several foodstuffs. Strontium-90 is thought to be the third most important residual radionuclide in food collected after the Fukushima Daiichi, NPP accident after following cesium-137 ((137)Cs) and cesium-134 ((134)Cs). Results of (90)Sr analyses indicated that (90)Sr was detect in 25 of the 40 radioactive cesium (r-Cs) positive samples collected in areas around the Fukushima Daiichi NPP, ranging in distance from 50 to 250 km. R-Cs positive samples were defined as containing both (134)Cs and (137)Cs which are considered to be indicators of the after-effects of the Fukushima Daiichi NPP accident. We also detected (90)Sr in 8 of 13 r-Cs negative samples, in which (134)Cs was not detected. Strontium-90 concentrations in the r-Cs positive samples did not significantly exceed the (90)Sr concentrations in r-Cs negative samples or the (90)Sr concentration ranges in comparable food groups found in previous surveys before the Fukushima Daiichi NPP accident. Thus, (90)Sr concentrations in r-Cs positive samples were indistinguishable from the background (90)Sr concentrations arising from global fallout prior to the Fukushima accident, suggesting that no marked increase of (90)Sr concentrations has occurred in r-Cs positive samples as a result of the Fukushima Daiichi NPP accident.

Accident information needs

International Nuclear Information System (INIS)

Hanson, D.J.; Arcieri, W.C.; Ward, L.W.

1992-01-01

A Five-step methodology has been developed to evaluate information needs for nuclear power plants under accident conditions and the availability of plant instrumentation during severe accidents. Step 1 examines the credible accidents and their relationships to plant safety functions. Step 2 determines the information personnel involved in accident management will need to understand plant behavior. Step 3 determines the capability of the instrumentation to function properly under severe accident conditions. Step 4 determines the conditions expected during the identified severe accidents. Step 5 compares the instrument capabilities and the severe accident conditions to evaluate the availability of the instrumentation to supply needed plant information

Accident information needs

Energy Technology Data Exchange (ETDEWEB)

Hanson, D.J.; Arcieri, W.C.; Ward, L.W.

1992-12-31

A Five-step methodology has been developed to evaluate information needs for nuclear power plants under accident conditions and the availability of plant instrumentation during severe accidents. Step 1 examines the credible accidents and their relationships to plant safety functions. Step 2 determines the information personnel involved in accident management will need to understand plant behavior. Step 3 determines the capability of the instrumentation to function properly under severe accident conditions. Step 4 determines the conditions expected during the identified severe accidents. Step 5 compares the instrument capabilities and the severe accident conditions to evaluate the availability of the instrumentation to supply needed plant information.

Accident information needs

Energy Technology Data Exchange (ETDEWEB)

Hanson, D.J.; Arcieri, W.C.; Ward, L.W.

1992-01-01

A Five-step methodology has been developed to evaluate information needs for nuclear power plants under accident conditions and the availability of plant instrumentation during severe accidents. Step 1 examines the credible accidents and their relationships to plant safety functions. Step 2 determines the information personnel involved in accident management will need to understand plant behavior. Step 3 determines the capability of the instrumentation to function properly under severe accident conditions. Step 4 determines the conditions expected during the identified severe accidents. Step 5 compares the instrument capabilities and the severe accident conditions to evaluate the availability of the instrumentation to supply needed plant information.

Mortality Rates of Traumatic Traffic Accident Patients at the University Hospital

Directory of Open Access Journals (Sweden)

Atilla Senih MAYDA

2014-05-01

Full Text Available The aim of the study is to estimate hospitalization and mortality rates in patients admitted to the University Hospital due to traffic accidents, and to determine the mean cost of the applicants in the hospital due to traffic accident. In this retrospective study data were obtained from the records of a university research and practice hospital. There were 802 patients admitted to emergency and other outpatient clinics of the University Hospital because of traffic accidents throughout the year 2012. Out of these patients, 166 (20.7% were hospitalized, and the annual mortality rate was 0.87%. The total cost was 322,545.2 euro and 402.2 euro per patient. Road traffic accident detection reports covered only the numbers of fatal injuries and injuries that happened at the scene of accidents. Determination of the number of the dead and wounded with overall mortality rate would be supposed to reveal the magnitude of public health problem caused by traffic accidents.

[Guilty victims: a model to perpetuate impunity for work-related accidents].

Science.gov (United States)

Vilela, Rodolfo Andrade Gouveia; Iguti, Aparecida Mari; Almeida, Ildeberto Muniz

2004-01-01

This article analyzes reports and data from the investigation of severe and fatal work-related accidents by the Regional Institute of Criminology in Piracicaba, São Paulo State, Brazil. Some 71 accident investigation reports were analyzed from 1998, 1999, and 2000. Accidents involving machinery represented 38.0% of the total, followed by high falls (15.5%), and electric shocks (11.3%). The reports conclude that 80.0% of the accidents are caused by "unsafe acts" committed by workers themselves, while the lack of safety or "unsafe conditions" account for only 15.5% of cases. Victims are blamed even in situations involving high risk in which not even minimum safety conditions are adopted, thus favoring employers' interests. Such conclusions reflect traditional reductionist explanatory models, in which accidents are viewed as simple, unicausal phenomena, generally focused on slipups and errors by the workers themselves. Despite criticism in recent decades from the technical and academic community, this concept is still hegemonic, thus jeopardizing the development of preventive policies and the improvement of work conditions.

Perspectives on phenomenology and simulation of severe accident in light water reactors

International Nuclear Information System (INIS)

Sugimoto, Jun

2014-01-01

Severe accident phenomena in light water reactors (LWRs) are generally characterized by their physically and chemically complex processes involved with high temperature core melt, multi-component and multi-phase flows, transport of radioactive materials and sometimes highly non-equilibrium state. Severe accident phenomenology is usually categorized into four phases; (1) fuel degradation, (2) in-vessel phenomena, (3) ex-vessel phenomena and (4) fission product release and transport. Among these, ex-vessel phenomena consist of five subcategories; 1) direct containment heating, 2) fuel coolant interaction (steam explosion), 3) molten core concrete interaction, 4) hydrogen behaviour and control and 5) containment failure/leakage. In the field of simulation of severe accident, severe accident analytical codes have been developed in the United States, EU and Japan, such as MAAP, MELCOR, ASTEC, THALES and SAMPSON. Many different kinds of analytical codes for the specific severe accident phenomena have also been developed worldwide. After the accident at Fukushima Daiichi Nuclear Power Station, review of severe accident research issues has been conducted and several issues are reconsidered, such as effects of BWR core degradation behaviors, sea water injection, pool scrubbing under rapid depressurization, containment failure/leakage and re-criticality. Some new experimental and analytical efforts have been started after the Fukushima accident. The present paper describes the perspectives on phenomenology and simulation of severe accident in LWRs, with the emphasis of insights obtained in the review of Fukushima accident. (author)

Applications of PRA in nuclear criticality safety

International Nuclear Information System (INIS)

McLaughlin, T.P.

1992-01-01

Traditionally, criticality accident prevention at Los Alamos National Laboratory (LANL) has been based on a thorough review and understanding of proposed operations or changes to operations involving both process supervision and criticality safety staff. The outcome of this communication was usually an agreement, based on professional judgment, that certain accident sequences were credible and had to be precluded by design; others were incredible and thus did not warrant expenditures to further reduce their likelihood. The extent of documentation was generally in proportion to the complexity of the operation but never as detailed as that associated with quantified risk assessments. During the last 3 yr, nuclear criticality safety-related probabilistic risk assessments (PRAs) have been performed on operations in two LANL facilities. Both of these were conducted in order to better understand the cost/benefit aspects of PRAs as they apply to largely hands-on operations with fissile material

Learning lessons from Natech accidents - the eNATECH accident database

Science.gov (United States)

Krausmann, Elisabeth; Girgin, Serkan

2016-04-01

When natural hazards impact industrial facilities that house or process hazardous materials, fires, explosions and toxic releases can occur. This type of accident is commonly referred to as Natech accident. In order to prevent the recurrence of accidents or to better mitigate their consequences, lessons-learned type studies using available accident data are usually carried out. Through post-accident analysis, conclusions can be drawn on the most common damage and failure modes and hazmat release paths, particularly vulnerable storage and process equipment, and the hazardous materials most commonly involved in these types of accidents. These analyses also lend themselves to identifying technical and organisational risk-reduction measures that require improvement or are missing. Industrial accident databases are commonly used for retrieving sets of Natech accident case histories for further analysis. These databases contain accident data from the open literature, government authorities or in-company sources. The quality of reported information is not uniform and exhibits different levels of detail and accuracy. This is due to the difficulty of finding qualified information sources, especially in situations where accident reporting by the industry or by authorities is not compulsory, e.g. when spill quantities are below the reporting threshold. Data collection has then to rely on voluntary record keeping often by non-experts. The level of detail is particularly non-uniform for Natech accident data depending on whether the consequences of the Natech event were major or minor, and whether comprehensive information was available for reporting. In addition to the reporting bias towards high-consequence events, industrial accident databases frequently lack information on the severity of the triggering natural hazard, as well as on failure modes that led to the hazmat release. This makes it difficult to reconstruct the dynamics of the accident and renders the development of

A Logic Architecture for 360 ADAS-Alerts for Hazards Detection Based in Driver Actions

Directory of Open Access Journals (Sweden)

Izquierdo-Reyes Javier

2017-01-01

Full Text Available In this work is presented a novel approach for passive safety in vehicles by Advanced Driver Assistance Systems (ADAS alert emission in 360° around driver to notify about hazards nearby the vehicle depending on the actions taken by driver per the context. This proposal would create a more robust system compared to current passive ADAS systems since the feedback to driver is in the same direction that hazard is detected (Punctual Sound Source Alert, compared with most assistance systems that emits sounds from the monitor or from the dashboard provoking distractions when emits alerts unnecessarily. The increase of security by this method will allow the driver to be aware of their surroundings even in a very quiet cabin or in a noisy environment. Also, it would detect the steering wheel angle, speed of movement and the activation of turning lights among other alerts, which would allow us to define a critical action during driving; apart from using sensors and cameras aimed at the driver to detect patterns of movement during these critical actions and have a prediction of a possible turn or manoeuvre when driving, refer to Figure 1. It will be necessary a reconfiguration of the alert in frequency, time of action depending upon the level of risk to prevent an accident or to reduce the consequences in an imminent accident.

Scoping Study Investigating PWR Instrumentation during a Severe Accident Scenario

Energy Technology Data Exchange (ETDEWEB)

Rempe, J. L. [Rempe and Associates, LLC, Idaho Falls, ID (United States); Knudson, D. L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lutz, R. J. [Lutz Nuclear Safety Consultant, LLC, Asheville, NC (United States)

2015-09-01

The accidents at the Three Mile Island Unit 2 (TMI-2) and Fukushima Daiichi Units 1, 2, and 3 nuclear power plants demonstrate the critical importance of accurate, relevant, and timely information on the status of reactor systems during a severe accident. These events also highlight the critical importance of understanding and focusing on the key elements of system status information in an environment where operators may be overwhelmed with superfluous and sometimes conflicting data. While progress in these areas has been made since TMI-2, the events at Fukushima suggests that there may still be a potential need to ensure that critical plant information is available to plant operators. Recognizing the significant technical and economic challenges associated with plant modifications, it is important to focus on instrumentation that can address these information critical needs. As part of a program initiated by the Department of Energy, Office of Nuclear Energy (DOE-NE), a scoping effort was initiated to assess critical information needs identified for severe accident management and mitigation in commercial Light Water Reactors (LWRs), to quantify the environment instruments monitoring this data would have to survive, and to identify gaps where predicted environments exceed instrumentation qualification envelop (QE) limits. Results from the Pressurized Water Reactor (PWR) scoping evaluations are documented in this report. The PWR evaluations were limited in this scoping evaluation to quantifying the environmental conditions for an unmitigated Short-Term Station BlackOut (STSBO) sequence in one unit at the Surry nuclear power station. Results were obtained using the MELCOR models developed for the US Nuclear Regulatory Commission (NRC)-sponsored State of the Art Consequence Assessment (SOARCA) program project. Results from this scoping evaluation indicate that some instrumentation identified to provide critical information would be exposed to conditions that

Microcontroller based driver alertness detection systems to detect drowsiness

Science.gov (United States)

Adenin, Hasibah; Zahari, Rahimi; Lim, Tiong Hoo

2018-04-01

The advancement of embedded system for detecting and preventing drowsiness in a vehicle is a major challenge for road traffic accident systems. To prevent drowsiness while driving, it is necessary to have an alert system that can detect a decline in driver concentration and send a signal to the driver. Studies have shown that traffc accidents usually occur when the driver is distracted while driving. In this paper, we have reviewed a number of detection systems to monitor the concentration of a car driver and propose a portable Driver Alertness Detection System (DADS) to determine the level of concentration of the driver based on pixelated coloration detection technique using facial recognition. A portable camera will be placed at the front visor to capture facial expression and the eye activities. We evaluate DADS using 26 participants and have achieved 100% detection rate with good lighting condition and a low detection rate at night.

Analysis of Two Electrocution Accidents in Greece that Occurred due to Unexpected Re-energization of Power Lines

Directory of Open Access Journals (Sweden)

Aikaterini D. Baka

2014-09-01

Full Text Available Investigation and analysis of accidents are critical elements of safety management. The over-riding purpose of an organization in carrying out an accident investigation is to prevent similar accidents, as well as seek a general improvement in the management of health and safety. Hundreds of workers have suffered injuries while installing, maintaining, or servicing machinery and equipment due to sudden re-energization of power lines. This study presents and analyzes two electrical accidents (1 fatal injury and 1 serious injury that occurred because the power supply was reconnected inadvertently or by mistake.

Analysis of Two Electrocution Accidents in Greece that Occurred due to Unexpected Re-energization of Power Lines.

Science.gov (United States)

Baka, Aikaterini D; Uzunoglu, Nikolaos K

2014-09-01

Investigation and analysis of accidents are critical elements of safety management. The over-riding purpose of an organization in carrying out an accident investigation is to prevent similar accidents, as well as seek a general improvement in the management of health and safety. Hundreds of workers have suffered injuries while installing, maintaining, or servicing machinery and equipment due to sudden re-energization of power lines. This study presents and analyzes two electrical accidents (1 fatal injury and 1 serious injury) that occurred because the power supply was reconnected inadvertently or by mistake.

Accident beyond the design basis management with the coolant loss at the NPP with WWER

International Nuclear Information System (INIS)

Skalozubov, V.I.; Klyuchnikov, A.A.; Kolykhanov, V.N.

2010-01-01

The analysis of status and experience of development on modelling and accident beyond the design basis management, including the severe accidents, at the nuclear power plants is carried out. The methodical providing of manuals on the accident beyond the design basis management with the coolant loss on the basis of simulated critical system configurations providing the necessary safety function performance on reactor unit is proposed. The project of symptom-oriented manuals on accident beyond the design basis management with the coolant loss on the serial power unit with WWER-1000 on the basis of developed methodical providing and well known results of deepened safety analysis is presented.

Goiania's radioactive accident - Evolutive description two years after

International Nuclear Information System (INIS)

Lamarck, P. de; Almeida Lignelli, O.J. de; Sobrinho, A.B.

1990-01-01

The authors lead a brief review of three patients that undergone lesions caused by ionizing radiations at the Goiania's radioactive accident, two years after. They describe the actual conditions of the skin lesions, hematologic values, sequels, diagnostic and therapeutics procedures on the follow up of this patients. They still make a comparative study between nuclear weapon's victims at Hiroshima and Nagasaki events (2 sup(nd) World War) and Goiania accident s victims. In their conclusions, the authors point out the importance in detecting early lesions, diseases or late sequels, due to radioactive expositions. (author)

An assessment of criticality safety at the Department of Energy Rocky Flats Plant, Golden, Colorado, July--September 1989

Energy Technology Data Exchange (ETDEWEB)

Mattson, Roger J.

1989-09-01

This is a report on the 1989 independent Criticality Safety Assessment of the Rocky Flats Plant, primarily in response to public concerns that nuclear criticality accidents involving plutonium may have occurred at this nuclear weapon component fabrication and processing plant. The report evaluates environmental issues, fissile material storage practices, ventilation system problem areas, and criticality safety practices. While no evidence of a criticality accident was found, several recommendations are made for criticality safety improvements. 9 tabs.

Twenty-first nuclear accident dosimetry intercomparison study, August 6-10, 1984

International Nuclear Information System (INIS)

Swaja, R.E.; Ragan, G.E.; Sims, C.S.

1985-05-01

The twenty-first in a series of nuclear accident dosimetry (NAD) intercomparison (NAD) studies was conducted at the Oak Ridge National Laboratory's Dosimetry Applications Research Facility during August 6-10, 1984. The Health Physics Research Reactor operated in the pulse mode was used to simulate three criticality accidents with different radiation fields. Participants from five organizations measured neutron doses between 0.53 and 4.36 Gy and gamma doses between 0.19 and 1.01 Gy at area monitoring stations and on phantoms. About 75% of all neutron dose estimates based on foil activation, hair activation, simulated blood sodium activation, and thermoluminescent methods were within +-25% of reference values. Approximately 86% of all gamma results measured using thermoluminescent (TLD-700 or CaSO 4 ) systems were within +-20% of reference doses which represents a significant improvement over previous studies. Improvements observed in the ability of intercomparison participants to estimate neutron and gamma doses under criticality accident conditions can be partly attributed to experience in previous NAD studies which have provided practical tests of dosimetry systems, enabled participants to improve evaluation methods, and standardized dose reporting conventions. 16 refs., 15 tabs

Martin Marietta Energy Systems Nuclear Criticality Safety Improvement Program

International Nuclear Information System (INIS)

Speas, I.G.

1987-01-01

This report addresses questions raised by criticality safety violation at several DOE plants. Two charts are included that define the severity and reporting requirements for the six levels of accidents. A summary is given of all reported criticality incident at the DOE plants involved. The report concludes with Martin Marietta's Nuclear Criticality Safety Policy Statement

Neural network-based expert system for severe accident management

International Nuclear Information System (INIS)

Klopp, G.T.; Silverman, E.B.

1992-01-01

This paper presents the results of the second phase of a three-phase Severe Accident Management expert system program underway at Commonwealth Edison Company (CECo). Phase I successfully demonstrated the feasibility of Artificial Neural Networks to support several of the objectives of severe accident management. Simulated accident scenarios were generated by the Modular Accident Analysis Program (MAAP) code currently in use by CECo as part of their Individual Plant Evaluations (IPE)/Accident Management Program. The primary objectives of the second phase were to develop and demonstrate four capabilities of neural networks with respect to nuclear power plant severe accident monitoring and prediction. The results of this work would form the foundation of a demonstration system which included expert system performance features. These capabilities included the ability to: (1) Predict the time available prior to support plate (and reactor vessel) failure; (2) Calculate the time remaining until recovery actions were too late to prevent core damage; (3) Predict future parameter values of each of the MAAP parameter variables; and (4) Detect simulated sensor failure and provide best-value estimates for further processing in the presence of a sensor failure. A variety of accident scenarios for the Zion and Dresden plants were used to train and test the neural network expert system. These included large and small break LOCAs as well as a range of transient events. 3 refs., 1 fig., 1 tab

Research on driver fatigue detection

Science.gov (United States)

Zhang, Ting; Chen, Zhong; Ouyang, Chao

2018-03-01

Driver fatigue is one of the main causes of frequent traffic accidents. In this case, driver fatigue detection system has very important significance in avoiding traffic accidents. This paper presents a real-time method based on fusion of multiple facial features, including eye closure, yawn and head movement. The eye state is classified as being open or closed by a linear SVM classifier trained using HOG features of the detected eye. The mouth state is determined according to the width-height ratio of the mouth. The head movement is detected by head pitch angle calculated by facial landmark. The driver's fatigue state can be reasoned by the model trained by above features. According to experimental results, drive fatigue detection obtains an excellent performance. It indicates that the developed method is valuable for the application of avoiding traffic accidents caused by driver's fatigue.

Lecture notes for criticality safety

International Nuclear Information System (INIS)

Fullwood, R.

1992-03-01

These lecture notes for criticality safety are prepared for the training of Department of Energy supervisory, project management, and administrative staff. Technical training and basic mathematics are assumed. The notes are designed for a two-day course, taught by two lecturers. Video tapes may be used at the options of the instructors. The notes provide all the materials that are necessary but outside reading will assist in the fullest understanding. The course begins with a nuclear physics overview. The reader is led from the macroscopic world into the microscopic world of atoms and the elementary particles that constitute atoms. The particles, their masses and sizes and properties associated with radioactive decay and fission are introduced along with Einstein's mass-energy equivalence. Radioactive decay, nuclear reactions, radiation penetration, shielding and health-effects are discussed to understand protection in case of a criticality accident. Fission, the fission products, particles and energy released are presented to appreciate the dangers of criticality. Nuclear cross sections are introduced to understand the effectiveness of slow neutrons to produce fission. Chain reactors are presented as an economy; effective use of the neutrons from fission leads to more fission resulting in a power reactor or a criticality excursion. The six-factor formula is presented for managing the neutron budget. This leads to concepts of material and geometric buckling which are used in simple calculations to assure safety from criticality. Experimental measurements and computer code calculations of criticality are discussed. To emphasize the reality, historical criticality accidents are presented in a table with major ones discussed to provide lessons-learned. Finally, standards, NRC guides and regulations, and DOE orders relating to criticality protection are presented

Thyroid blocking after nuclear accidents

International Nuclear Information System (INIS)

Rendl, J.; Reiners, C.

1999-01-01

Following the Chernobyl accident a marked increase in thyroid cancer incidence among the children in Belarus, the Ukraine and Russia has been detected, strongly suggesting a causal relationship to the large amounts of radioactive iodine isotopes in the resulting fallout. Taking into account the Chernobyl experience the German Committee on Radiation Protection decided to reduce the intervention levels on the basis of the 1989 WHO recommendations and adopted a new concept concerning thyroid blocking in response to nuclear power plant accidents. Experimental animal studies and theoretical considerations show that thyroid blocking with potassium iodide (KI) in a dose of about 1.4 mg per kg body weight is most effective in reducing irradiation to the thyroid from the intake of radioiodine nuclides, provided KI is given within 2 hours after exposure. According to the new concept, persons over 45 years of age should not take iodine tablets because the drug could cause a greater health risk due to prevalent functional thyroid autonomy in this age group than the radioactive iodine averted by KI. On the basis of accident analysis and the new philosophy suitable distribution strategies and logistics are proposed and discussed. (orig.) [de

Analysis of tritium mission FMEF/FAA fuel handling accidents

Energy Technology Data Exchange (ETDEWEB)

Van Keuren, J.C.

1997-11-18

The Fuels Material Examination Facility/Fuel Assembly Area is proposed to be used for fabrication of mixed oxide fuel to support the Fast Flux Test Facility (FFTF) tritium/medical isotope mission. The plutonium isotope mix for the new mission is different than that analyzed in the FMEF safety analysis report. A reanalysis was performed of three representative accidents for the revised plutonium mix to determine the impact on the safety analysis. Current versions computer codes and meterology data files were used for the analysis. The revised accidents were a criticality, an explosion in a glovebox, and a tornado. The analysis concluded that risk guidelines were met with the revised plutonium mix.

The radiation accident at Juarez

International Nuclear Information System (INIS)

Koenig, L.A.

1985-01-01

During unconscious disassembly of a Co-60 therapy unit, 6010 metal pellets of 1 mm diameter each having 2.6 GBq (70 mCi) of activity were distributed in an uncontrolled manner. The incident was detected by mere chance. The event and the consequences are illustrated. The resulting collective dose is estimated to be 100 times bigger than that caused by the Harrisburg accident. (orig.) [de

Thermal-hydraulic analysis under partial loss of flow accident hypothesis of a plate-type fuel surrounded by two water channels using RELAP5 code

Directory of Open Access Journals (Sweden)

Itamar Iliuk

2016-01-01

Full Text Available Thermal-hydraulic analysis of plate-type fuel has great importance to the establishment of safety criteria, also to the licensing of the future nuclear reactor with the objective of propelling the Brazilian nuclear submarine. In this work, an analysis of a single plate-type fuel surrounding by two water channels was performed using the RELAP5 thermal-hydraulic code. To realize the simulations, a plate-type fuel with the meat of uranium dioxide sandwiched between two Zircaloy-4 plates was proposed. A partial loss of flow accident was simulated to show the behavior of the model under this type of accident. The results show that the critical heat flux was detected in the central region along the axial direction of the plate when the right water channel was blocked.

Key Characteristics of Combined Accident including TLOFW accident for PSA Modeling

Energy Technology Data Exchange (ETDEWEB)

Kim, Bo Gyung; Kang, Hyun Gook [KAIST, Daejeon (Korea, Republic of); Yoon, Ho Joon [Khalifa University of Science, Technology and Research, Abu Dhabi (United Arab Emirates)

2015-05-15

The conventional PSA techniques cannot adequately evaluate all events. The conventional PSA models usually focus on single internal events such as DBAs, the external hazards such as fire, seismic. However, the Fukushima accident of Japan in 2011 reveals that very rare event is necessary to be considered in the PSA model to prevent the radioactive release to environment caused by poor treatment based on lack of the information, and to improve the emergency operation procedure. Especially, the results from PSA can be used to decision making for regulators. Moreover, designers can consider the weakness of plant safety based on the quantified results and understand accident sequence based on human actions and system availability. This study is for PSA modeling of combined accidents including total loss of feedwater (TLOFW) accident. The TLOFW accident is a representative accident involving the failure of cooling through secondary side. If the amount of heat transfer is not enough due to the failure of secondary side, the heat will be accumulated to the primary side by continuous core decay heat. Transients with loss of feedwater include total loss of feedwater accident, loss of condenser vacuum accident, and closure of all MSIVs. When residual heat removal by the secondary side is terminated, the safety injection into the RCS with direct primary depressurization would provide alternative heat removal. This operation is called feed and bleed (F and B) operation. Combined accidents including TLOFW accident are very rare event and partially considered in conventional PSA model. Since the necessity of F and B operation is related to plant conditions, the PSA modeling for combined accidents including TLOFW accident is necessary to identify the design and operational vulnerabilities.The PSA is significant to assess the risk of NPPs, and to identify the design and operational vulnerabilities. Even though the combined accident is very rare event, the consequence of combined

Dose evaluation based on {sup 24}Na activity in the human body at the JCO criticality accident in Tokai-mura

Energy Technology Data Exchange (ETDEWEB)

Momose, Takumaro; Tsujimura, Norio; Tasaki, Takashi; Kanai, Katsuta; Kurihara, Osamu; Hayashi, Naomi; Shinohara, Kunihiko [Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan). Tokai Works

2001-09-01

{sup 24}Na in the human body, activated by neutrons emitted at the JCO criticality accident, was observed for 62 subjects, where 148 subjects were measured by the whole body counter of JNC Tokai Works. The 148 subjects, including JCO employees and the contractors, residents neighboring the site and emergency service officers, were measured by the whole-body counter. The neutron-energy spectrum around the facility was calculated using neutron transport codes (ANISN and MCNP), and the relation between an amount of activated sodium in human body and neutron dose was evaluated from the calculated neutron energy spectrum and theoretical neutron capture probability by the human body. The maximum {sup 24}Na activity in the body was 7.7 kBq (83 Bq({sup 24}Na)/g({sup 23}Na)) and the relevant effective dose equivalent was 47 mSv. (author)

Identification of the operating crew's information needs for accident management

Energy Technology Data Exchange (ETDEWEB)

Nelson, W.R.; Hanson, D.J.; Ward, L.W.; Solberg, D.E.

1988-01-01

While it would be very difficult to predetermine all of the actions required to mitigate the consequences of every potential severe accident for a nuclear power plant, development of additional guidance and training could improve the likelihood that the operating crew would implement effective sever-accident management measures. The US Nuclear Regulatory Commission (NRC) is conducting an Accident Management Research Program that emphasizes the application of severe-accident research results to enhance the capability of the plant operating crew to effectively manage severe accidents. One element of this program includes identification of the information needed by the operating crew in severe-accident situations. This paper discusses a method developed for identifying these information needs and its application. The methodology has been applied to a generic reactor design representing a PWR with a large dry containment. The information needs were identified by systematically determining what information is needed to assess the health of the critical functions, identify the presence of challenges, select strategies, and assess the effectiveness of these strategies. This method allows the systematic identification of information needs for a broad range of severe-accident scenarios and can be validated by exercising the functional models for any specific event sequence.

Severe accidents at nuclear power plants. Their risk assessment and accident management

International Nuclear Information System (INIS)

Abe, Kiyoharu.

1995-05-01

This document is to explain the severe accident issues. Severe Accidents are defined as accidents which are far beyond the design basis and result in severe damage of the core. Accidents at Three Mild Island in USA and at Chernobyl in former Soviet Union are examples of severe accidents. The causes and progressions of the accidents as well as the actions taken are described. Probabilistic Safety Assessment (PSA) is a method to estimate the risk of severe accidents at nuclear reactors. The methodology for PSA is briefly described and current status on its application to safety related issues is introduced. The acceptability of the risks which inherently accompany every technology is then discussed. Finally, provision of accident management in Japan is introduced, including the description of accident management measures proposed for BWRs and PWRs. (author)

Accidents and transients analyses of a super fast reactor with single flow pass core

International Nuclear Information System (INIS)

Sutanto,; Oka, Yoshiaki

2014-01-01

Highlights: • Safety analysis of a Super FR with single flow pass core is conducted. • Loss of feed water flow leads to a direct effect on the loss of fuel channel flow. • The core pressure is sensitive to LOCA accidents due to the direct effect. • Small LOCA introduces a critical break. • The safety criteria for all selected events are satisfied. - Abstract: The supercritical water cooled fast reactor with single flow pass core has been designed to simplify refueling and the structures of upper and lower mixing plenums. To evaluate the safety performance, safety analysis has been conducted with regard to LOCA and non-LOCA accidents including transient events. Safety analysis results show that the safety criteria are satisfied for all selected events. The total loss of feed water flow is the most important accident which the maximum cladding surface temperature (MCST) is high due to a direct effect of the accident on the total loss of flow in all fuel assemblies. However, actuation of the ADS can mitigate the accident. Small LOCA also introduces a critical break at 7.8% break which results high MCST at BOC because the scram and ADS are not actuated. Early ADS actuation is effective to mitigate the accident. In large LOCA, 100% break LOCA results a high MCST of flooding phase at BOC due to high power peaking at the bottom part. Use of high injection flow rate by 2 LPCI units is effective to decrease the MCST

Accident identification system with automatic detection of abnormal condition using quantum computation

International Nuclear Information System (INIS)

Nicolau, Andressa dos Santos; Schirru, Roberto; Lima, Alan Miranda Monteiro de

2011-01-01

Transient identification systems have been proposed in order to maintain the plant operating in safe conditions and help operators in make decisions in emergency short time interval with maximum certainty associated. This article presents a system, time independent and without the use of an event that can be used as a starting point for t = 0 (reactor scram, for instance), for transient/accident identification of a pressurized water nuclear reactor (PWR). The model was developed in order to be able to recognize the normal condition and three accidents of the design basis list of the Nuclear Power Plant Angra 2, postulated in the Final Safety Analysis Report (FSAR). Were used several sets of process variables in order to establish a minimum set of variables considered necessary and sufficient. The optimization step of the identification algorithm is based upon the paradigm of Quantum Computing. In this case, the optimization metaheuristic Quantum Inspired Evolutionary Algorithm (QEA) was implemented and works as a data mining tool. The results obtained with the QEA without the time variable are compatible to the techniques in the reference literature, for the transient identification problem, with less computational effort (number of evaluations). This system allows a solution that approximates the ideal solution, the Voronoi Vectors with only one partition for the classes of accidents with robustness. (author)

Automatic RST-based system for a rapid detection of man-made disasters

Science.gov (United States)

Tramutoli, Valerio; Corrado, Rosita; Filizzola, Carolina; Livia Grimaldi, Caterina Sara; Mazzeo, Giuseppe; Marchese, Francesco; Pergola, Nicola

2010-05-01

Man-made disasters may cause injuries to citizens and damages to critical infrastructures. When it is not possible to prevent or foresee such disasters it is hoped at least to rapidly detect the accident in order to intervene as soon as possible to minimize damages. In this context, the combination of a Robust Satellite Technique (RST), able to identify for sure actual (i.e. no false alarm) accidents, and satellite sensors with high temporal resolution seems to assure both a reliable and a timely detection of abrupt Thermal Infrared (TIR) transients related to dangerous explosions. A processing chain, based on the RST approach, has been developed in the framework of the GMOSS and G-MOSAIC projects by DIFA-UNIBAS team, suitable for automatically identify on MSG-SEVIRI images harmful events. Maps of thermal anomalies are generated every 15 minutes (i.e. SEVIRI temporal repetition rate) over a selected area together with kml files (containing information on latitude and longitude of "thermally" anomalous SEVIRI pixel centre, time of image acquisition, relative intensity of anomalies, etc.) for a rapid visualization of the accident position even on Google Earth. Results achieved in the cases of gas pipelines recently exploded or attacked in Russia and in Iraq will be presented in this work.

Third IAEA nuclear accident intercomparison experiment

Energy Technology Data Exchange (ETDEWEB)

Miric, I; Ubovic, Z

1974-05-15

The purpose of this report is to present the results of the International Atomic Energy Agency intercomparison experiments held at the 'Boris Kidric' Institute, Vinca, in May 1973. The experiments are parts of a multilaboratory intercomparison programme sponsored by the IAEA for the evaluation of nuclear accident dosimetry systems and eventually recommendation of dosimetry systems that will provide adequate informations in the event of a criticality accident. The previous two studies were held at the Valduc Centre near Dijon (France) in June 1970 and at the ORNL in Oak Ridge (USA), in May 1971. Parts of the intercomparison studies were coordination meetings. The topics and conclusions of the Third coordination meeting are given in the Chairman's Report of F.F. Haywood. This paper will deal, therefore, only with data concerning the Third intercomparison experiments in which the RB reactor at Vinca was used as a source of mixed radiation. (author)

Third IAEA nuclear accident intercomparison experiment

International Nuclear Information System (INIS)

Miric, I.; Ubovic, Z.

1974-05-01

The purpose of this report is to present the results of the International Atomic Energy Agency intercomparison experiments held at the 'Boris Kidric' Institute, Vinca, in May 1973. The experiments are parts of a multilaboratory intercomparison programme sponsored by the IAEA for the evaluation of nuclear accident dosimetry systems and eventually recommendation of dosimetry systems that will provide adequate informations in the event of a criticality accident. The previous two studies were held at the Valduc Centre near Dijon (France) in June 1970 and at the ORNL in Oak Ridge (USA), in May 1971. Parts of the intercomparison studies were coordination meetings. The topics and conclusions of the Third coordination meeting are given in the Chairman's Report of F.F. Haywood. This paper will deal, therefore, only with data concerning the Third intercomparison experiments in which the RB reactor at Vinca was used as a source of mixed radiation. (author)

Human factors review for Severe Accident Sequence Analysis (SASA)

International Nuclear Information System (INIS)

Krois, P.A.; Haas, P.M.; Manning, J.J.; Bovell, C.R.

1984-01-01

The paper will discuss work being conducted during this human factors review including: (1) support of the Severe Accident Sequence Analysis (SASA) Program based on an assessment of operator actions, and (2) development of a descriptive model of operator severe accident management. Research by SASA analysts on the Browns Ferry Unit One (BF1) anticipated transient without scram (ATWS) was supported through a concurrent assessment of operator performance to demonstrate contributions to SASA analyses from human factors data and methods. A descriptive model was developed called the Function Oriented Accident Management (FOAM) model, which serves as a structure for bridging human factors, operations, and engineering expertise and which is useful for identifying needs/deficiencies in the area of accident management. The assessment of human factors issues related to ATWS required extensive coordination with SASA analysts. The analysis was consolidated primarily to six operator actions identified in the Emergency Procedure Guidelines (EPGs) as being the most critical to the accident sequence. These actions were assessed through simulator exercises, qualitative reviews, and quantitative human reliability analyses. The FOAM descriptive model assumes as a starting point that multiple operator/system failures exceed the scope of procedures and necessitates a knowledge-based emergency response by the operators. The FOAM model provides a functionally-oriented structure for assembling human factors, operations, and engineering data and expertise into operator guidance for unconventional emergency responses to mitigate severe accident progression and avoid/minimize core degradation. Operators must also respond to potential radiological release beyond plant protective barriers. Research needs in accident management and potential uses of the FOAM model are described. 11 references, 1 figure

Severe accident phenomena

International Nuclear Information System (INIS)

Jokiniemi, J.; Kilpi, K.; Lindholm, I.; Maekynen, J.; Pekkarinen, E.; Sairanen, R.; Silde, A.

1995-02-01

Severe accidents are nuclear reactor accidents in which the reactor core is substantially damaged. The report describes severe reactor accident phenomena and their significance for the safety of nuclear power plants. A comprehensive set of phenomena ranging from accident initiation to containment behaviour and containment integrity questions are covered. The report is based on expertise gained in the severe accident assessment projects conducted at the Technical Research Centre of Finland (VTT). (49 refs., 32 figs., 12 tabs.)

A systems approach to the management of radiation accidents

International Nuclear Information System (INIS)

Richter, L.L.; Berk, H.W.; Teates, C.D.; Larkham, N.E.; Friesen, E.J.; Edlich, R.F.

1980-01-01

Management of radiation accident patients should have a multidisciplinary approach that includes all health professionals as well as members of public safety agencies. Emergency plans for radiation accidents include detection of the ionizing radiation, patient evacuation, resuscitation, and decontamination. The resuscitated patient should be transported to a radiation control area located outside but adjacent to the emergency department. Ideally this area is accessed through an entrance separate from that used for the main flow of daily emergency department patients. The hospital staff, provided with protective clothing, dosimeters, and preprinted guidelines, continues the resuscitation and definitive care of the patient. This system approach to the management of radiation accidents may be tailored to meet the specific needs of other emergency medical systems

USNRC licensing process as related to nuclear criticality safety

International Nuclear Information System (INIS)

Ketzlach, N.

1987-01-01

The U.S. Code of Federal Regulations establishes procedures and criteria for the issuance of licenses to receive title to, own, acquire, deliver, receive, possess, use, and initially transfer special nuclear material; and establishes and provides for the terms and conditions upon which the Nuclear Regulatory Commission (NRC) will issue such licenses. Section 70.22 of the regulations, ''Contents of Applications'', requires that applications for licenses contain proposed procedures to avoid accidental conditions of criticality. These procedures are elements of a nuclear criticality safety program for operations with fissionable materials at fuels and materials facilities (i.e., fuel cycle facilities other than nuclear reactors) in which there exists a potential for criticality accidents. To assist the applicant in providing specific information needed for a nuclear criticality safety program in a license application, the NRC has issued regulatory guides. The NRC requirements for nuclear criticality safety include organizational, administrative, and technical requirements. For purely technical matters on nuclear criticality safety these guides endorse national standards. Others provide guidance on the standard format and content of license applications, guidance on evaluating radiological consequences of criticality accidents, or guidance for dealing with other radiation safety issues. (author)

Professional experience and traffic accidents/near-miss accidents among truck drivers.

Science.gov (United States)

Girotto, Edmarlon; Andrade, Selma Maffei de; González, Alberto Durán; Mesas, Arthur Eumann

2016-10-01

To investigate the relationship between the time working as a truck driver and the report of involvement in traffic accidents or near-miss accidents. A cross-sectional study was performed with truck drivers transporting products from the Brazilian grain harvest to the Port of Paranaguá, Paraná, Brazil. The drivers were interviewed regarding sociodemographic characteristics, working conditions, behavior in traffic and involvement in accidents or near-miss accidents in the previous 12 months. Subsequently, the participants answered a self-applied questionnaire on substance use. The time of professional experience as drivers was categorized in tertiles. Statistical analyses were performed through the construction of models adjusted by multinomial regression to assess the relationship between the length of experience as a truck driver and the involvement in accidents or near-miss accidents. This study included 665 male drivers with an average age of 42.2 (±11.1) years. Among them, 7.2% and 41.7% of the drivers reported involvement in accidents and near-miss accidents, respectively. In fully adjusted analysis, the 3rd tertile of professional experience (>22years) was shown to be inversely associated with involvement in accidents (odds ratio [OR] 0.29; 95% confidence interval [CI] 0.16-0.52) and near-miss accidents (OR 0.17; 95% CI 0.05-0.53). The 2nd tertile of professional experience (11-22 years) was inversely associated with involvement in accidents (OR 0.63; 95% CI 0.40-0.98). An evident relationship was observed between longer professional experience and a reduction in reporting involvement in accidents and near-miss accidents, regardless of age, substance use, working conditions and behavior in traffic. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fifteenth nuclear accident dosimetry intercomparison study: August 14--22, 1978

International Nuclear Information System (INIS)

Sims, C.S.

1979-05-01

The fifteenth in the continuing series of Nuclear Accident Dosimetry Intercomparison Studies was held August 14--22, 1978 at the Oak Ridge National Laboratory. The Health Physics Research Reactor, operated in the pulse mode, served as the radiation source. Using different shielding configurations, nuclear accidents with three different neutron and gamma spectra were simulated. Participants from 19 organizations, the most in the history of the studies, exposed dosimeters set up as area monitors as well as dosimeters mounted on phantoms for personnel monitoring. Although many participants performed accurate measurements, the composite dose results, in the majority of cases, failed to meet established nuclear criticality accident dosimetry guidelines which suggest accuracies of +- 25% for neutron dose and +- 20% for gamma dose. This indicates that many participants need to improve their dosimetry systems, their analytical techniques, or both

Accident-tolerant control rod

International Nuclear Information System (INIS)

Ohta, Hirokazu; Sawabe, Takashi; Ogata, Takanari

2013-01-01

Boron carbide (B 4 C) and hafnium (Hf) metal are used for the neutron absorber materials of control rods in BWRs, and silver-indium-cadmium (Ag-In-Cd) alloy is used in PWRs. These materials are clad with stainless steel. The eutectic point of B 4 C and iron (Fe) is about 1150 deg. C and the melting point of Ag-In-Cd alloy is about 800 deg. C, which are lower than the temperature of zircaloy - steam reaction increases rapidly (∼1200 deg. C). Accordingly, it is possible that the control rods melt and collapse before the reactor core is significantly damaged in the case of severe accidents. Since the neutron absorber would be separated from the fuels, there is a risk of re-criticality, when pure water or seawater is injected for emergency cooling. In order to ensure sub-criticality and extend options of emergency cooling in the course of severe accidents, a concept of accident-tolerant control rod (ACT) has been derived. ACT utilises a new absorber material having the following properties: - higher neutron absorption than current control rod; - higher melting or eutectic temperature than 1200 deg. C where rapid zircaloy oxidation occurs; - high miscibility with molten fuel materials. The candidate of a new absorber material for ATC includes gadolinia (Gd 2 O 3 ), samaria (Sm 2 O 3 ), europia (Eu 2 O 3 ), dysprosia (Dy 2 O 3 ), hafnia (HfO 2 ). The melting point of these materials and the liquefaction temperature with Fe are higher than the rapid zircaloy oxidation temperature. ACT will not collapse before the core melt-down. After the core melt-down, the absorber material will be mixed with molten fuel material. The current absorber materials, such as B 4 C, Hf and Ag-In-Cd, are charged at the tip of ATC in which the neutron flux is high, and a new absorber material is charged in the low-flux region. This design could minimise the degradation of a new absorber material by the neutron absorption and the influence of ATC deployment on reactor control procedure. As a

Criticality safety basics, a study guide

Energy Technology Data Exchange (ETDEWEB)

V. L. Putman

1999-09-01

This document is a self-study and classroom guide, for criticality safety of activities with fissile materials outside nuclear reactors. This guide provides a basic overview of criticality safety and criticality accident prevention methods divided into three parts: theory, application, and history. Except for topic emphasis, theory and history information is general, while application information is specific to the Idaho National Engineering and Environmental Laboratory (INEEL). Information presented here should be useful to personnel who must know criticality safety basics to perform their assignments safely or to design critically safe equipment or operations. However, the guide's primary target audience is fissile material handler candidates.

Criticality safety basics, a study guide

International Nuclear Information System (INIS)

Putman, V.L.

1999-01-01

This document is a self-study and classroom guide, for criticality safety of activities with fissile materials outside nuclear reactors. This guide provides a basic overview of criticality safety and criticality accident prevention methods divided into three parts: theory, application, and history. Except for topic emphasis, theory and history information is general, while application information is specific to the Idaho National Engineering and Environmental Laboratory (INEEL). Information presented here should be useful to personnel who must know criticality safety basics to perform their assignments safely or to design critically safe equipment or operations. However, the guide's primary target audience is fissile material handler candidates

Using a higher criticism statistic to detect modest effects in a genome-wide study of rheumatoid arthritis

Science.gov (United States)

2009-01-01

In high-dimensional studies such as genome-wide association studies, the correction for multiple testing in order to control total type I error results in decreased power to detect modest effects. We present a new analytical approach based on the higher criticism statistic that allows identification of the presence of modest effects. We apply our method to the genome-wide study of rheumatoid arthritis provided in the Genetic Analysis Workshop 16 Problem 1 data set. There is evidence for unknown bias in this study that could be explained by the presence of undetected modest effects. We compared the asymptotic and empirical thresholds for the higher criticism statistic. Using the asymptotic threshold we detected the presence of modest effects genome-wide. We also detected modest effects using 90th percentile of the empirical null distribution as a threshold; however, there is no such evidence when the 95th and 99th percentiles were used. While the higher criticism method suggests that there is some evidence for modest effects, interpreting individual single-nucleotide polymorphisms with significant higher criticism statistics is of undermined value. The goal of higher criticism is to alert the researcher that genetic effects remain to be discovered and to promote the use of more targeted and powerful studies to detect the remaining effects. PMID:20018032

The Chernobyl accident: Causes and consequences

International Nuclear Information System (INIS)

Malinauskas, A.P.

1987-01-01

Two explosions, one immediately following the other, in Unit 4 of the Chernobyl nuclear power station in the Soviet Union signaled the worst disaster ever to befall the commercial nuclear power production industry. This accident, which occurred at 1:24 a.m. on April 26, 1986, resulted from an almost incredible series of operational errors associated, ironically, with an attempt to enhance the capability of the reactor to safely accommodate station blackout accidents (i.e., accidents arising from a loss of station electrical power). Disruption of the core, due to a prompt criticality excursion, resulted in the destruction of the core vault and reactor building and the sudden dispersal of about 3% of the fuel from the core region into the environment. Lesser but significant releases of radioactivity continued through May 6, 1986, before attempts to certain the radioactivity and cool the remnants of the core were successful. The amount and composition of material released in the course of the accident remain somewhat uncertain, and inconsistencies in the release estimates are evident. The Soviet estimates, in addition to the dispersal of about 3% of the fuel, include complete release of the noble gas core inventory, 20% of the fission product iodine inventory, 15% of the tellurium inventory, and 10 to 13% of the fission product cesium inventory. The iodine and cesium release estimates are not consistent with the noble gas values, and are as much as a factor of two less than some estimates made by experts outside the Soviet Union

DRDC Ottawa Participation in the SILENE Accident Dosimetry Intercomparison Exercise. June 10-21, 2002

National Research Council Canada - National Science Library

Prud'homme-Lalonde, L

2002-01-01

.... The SILENE International Accident Dosimetry Intercomparison Exercise at Valduc, France in June 2002 coincided with DRDC Ottawa work designed to refine its proposed criticality dosimetry system...

Radiocontamination of agricultural workers due to nuclear accidents

International Nuclear Information System (INIS)

Petrovic, B.; Smelcerovic, M.; Djuric, G.; Popovic, D.

1989-01-01

In the radiocontamination of the environment due to nuclear accidents, agricultural workers should be considered as a critical group of population. The presented paper discusses this problem from the aspects of folder production. The values of the effective dose equivalent are estimated for different phases of the production process and certain procedures aimed to reduce the radiation risk are proposed (author)

Radiocontamination of agricultural workers due to nuclear accidents

Energy Technology Data Exchange (ETDEWEB)

Petrovic, B [Faculty of Veterinary Medicine, Beograd, (Serbia and Montenegro); Smelcerovic, M; Djuric, G; Popovic, D [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Serbia and Montenegro)

1989-07-01

In the radiocontamination of the environment due to nuclear accidents, agricultural workers should be considered as a critical group of population. The presented paper discusses this problem from the aspects of folder production. The values of the effective dose equivalent are estimated for different phases of the production process and certain procedures aimed to reduce the radiation risk are proposed (author)

Prevention of pedestrian accidents.

OpenAIRE

Kendrick, D

1993-01-01

Child pedestrian accidents are the most common road traffic accident resulting in injury. Much of the existing work on road traffic accidents is based on analysing clusters of accidents despite evidence that child pedestrian accidents tend to be more dispersed than this. This paper analyses pedestrian accidents in 573 children aged 0-11 years by a locally derived deprivation score for the years 1988-90. The analysis shows a significantly higher accident rate in deprived areas and a dose respo...

Accident Locations, MDTA Accidents, Accidents on MDTA locations, Accidents on I 95, US 50, I 695, Accident on John F Kennedy Highway, Nice Bridge, Bay Bridge locations, Published in 2011, 1:1200 (1in=100ft) scale, Maryland Transportation Authority.

Data.gov (United States)

NSGIC State | GIS Inventory — Accident Locations dataset current as of 2011. MDTA Accidents, Accidents on MDTA locations, Accidents on I 95, US 50, I 695, Accident on John F Kennedy Highway, Nice...

Hazards and accident analyses, an integrated approach, for the Plutonium Facility at Los Alamos National Laboratory

International Nuclear Information System (INIS)

Pan, P.Y.; Goen, L.K.; Letellier, B.C.; Sasser, M.K.

1995-01-01

This paper describes an integrated approach to perform hazards and accident analyses for the Plutonium Facility at Los Alamos National Laboratory. A comprehensive hazards analysis methodology was developed that extends the scope of the preliminary/process hazard analysis methods described in the AIChE Guidelines for Hazard Evaluations. Results fro the semi-quantitative approach constitute a full spectrum of hazards. For each accident scenario identified, there is a binning assigned for the event likelihood and consequence severity. In addition, each accident scenario is analyzed for four possible sectors (workers, on-site personnel, public, and environment). A screening process was developed to link the hazard analysis to the accident analysis. Specifically the 840 accident scenarios were screened down to about 15 accident scenarios for a more through deterministic analysis to define the operational safety envelope. The mechanics of the screening process in the selection of final scenarios for each representative accident category, i.e., fire, explosion, criticality, and spill, is described

Tank farm nuclear criticality review

International Nuclear Information System (INIS)

Bratzel, D.R.

1996-01-01

The technical basis for the nuclear criticality safety of stored wastes at the Hanford Site Tank Farm Complex was reviewed by a team of senior technical personnel whose expertise covered all appropriate aspects of fissile materials chemistry and physics. The team concluded that the detailed and documented nucleonics-related studies underlying the waste tanks criticality safety basis were sound. The team concluded that, under current plutonium inventories and operating conditions, a nuclear criticality accident is incredible in any of the Hanford single-shell tanks (SST), double-shell tanks (DST), or double-contained receiver tanks (DCRTS) on the Hanford Site

Criticality handbook. Pt. 1

International Nuclear Information System (INIS)

Heinicke, W.; Krug, H.; Thomas, W.; Weber, W.; Gmal, B.

1985-12-01

The GRS Criticality Handbook is intended as a source of information on criticality problems for the persons concerned in industry, authorities, or research laboratories. It is to serve as a guide allowing quick and appropriate evaluation of criticality problems during design or erection of nuclear installations. This present issue replaces the one published in 1979, presenting revised and new data in a modified construction, but within the framework of the proven basic structure of the Handbook. Some fundamental knowledge is required of criticality problems and the relevant terms and definitions of nuclear safety, in order to fully deploy the information given. Part 1 of the Handbook therefore first introduces terminology and definitions, followed by experimental methods and calculation models for criticality calculations. The next chapters deal with the function and efficiency of neutron reflectors and neutron absorbers, measuring methods for criticality monitoring, organisational safety measures, and criticality accidents and their subsequent analysis. (orig./HP) [de

Modelling Accident Tolerant Fuel Concepts

Energy Technology Data Exchange (ETDEWEB)

Hales, Jason Dean [Idaho National Laboratory; Gamble, Kyle Allan Lawrence [Idaho National Laboratory

2016-05-01

The catastrophic events that occurred at the Fukushima-Daiichi nuclear power plant in 2011 have led to widespread interest in research of alternative fuels and claddings that are proposed to be accident tolerant. The United States Department of Energy (DOE) through its Nuclear Energy Advanced Modeling and Simulation (NEAMS) program has funded an Accident Tolerant Fuel (ATF) High Impact Problem (HIP). The ATF HIP is a three-year project to perform research on two accident tolerant concepts. The final outcome of the ATF HIP will be an in-depth report to the DOE Advanced Fuels Campaign (AFC) giving a recommendation on whether either of the two concepts should be included in their lead test assembly scheduled for placement into a commercial reactor in 2022. The two ATF concepts under investigation in the HIP are uranium silicide fuel and iron-chromium-aluminum (FeCrAl) alloy cladding. Utilizing the expertise of three national laboratory participants (Idaho National Laboratory, Los Alamos National Laboratory, and Argonne National Laboratory), a comprehensive multiscale approach to modeling is being used that includes atomistic modeling, molecular dynamics, rate theory, phase-field, and fuel performance simulations. Model development and fuel performance analysis are critical since a full suite of experimental studies will not be complete before AFC must prioritize concepts for focused development. In this paper, we present simulations of the two proposed accident tolerance fuel systems: U3Si2 fuel with Zircaloy-4 cladding, and UO2 fuel with FeCrAl cladding. Sensitivity analyses are completed using Sandia National Laboratories’ Dakota software to determine which input parameters (e.g., fuel specific heat) have the greatest influence on the output metrics of interest (e.g., fuel centerline temperature). We also outline the multiscale modelling approach being employed. Considerable additional work is required prior to preparing the recommendation report for the Advanced

Biological and medical consequences of nuclear accidents

International Nuclear Information System (INIS)

Latarjet, R.

1988-01-01

The study of the medical and biological consequences of the nuclear accidents is a vast program. The Chernobyl accident has caused some thirty deceases: Some of them were rapid and the others occurred after a certain time. The particularity of these deaths was that the irradiation has been associated to burns and traumatisms. The lesson learnt from the Chernobyl accident is to treat the burn and the traumatism before treating the irradiation. Contrary to what the research workers believe, the first wave of deaths has passed between 15 and 35 days and it has not been followed by any others. But the therapeutic lesson drawn from the accident confirm the research workers results; for example: the radioactive doses band that determines where the therapy could be efficacious or not. the medical cares dispensed to the irradiated people in the hospital of Moscow has confirmed that the biochemical equilibrium of proteinic elements of blood has to be maintained, and the transfusion of the purified elements are very important to restore a patient to health, and the sterilization of the medium (room, food, bedding,etc...) of the patient is indispensable. Therefore, it is necessary to establish an international cooperation for providing enough sterilized rooms and specialists in the irradiation treatment. The genetic consequences and cancers from the Chernobyl accident have been discussed. It is impossible to detect these consequences because of their negligible percentages. (author)

Cytogenetical dose estimation for 3 severely exposed patients in the JCO criticality accident in Tokai-mura

International Nuclear Information System (INIS)

Hayata, Isamu; Kanda, Reiko; Minamihisamatsu, Masako; Furukawa, Akira; Sasaki, Masao S.

2001-01-01

A dose estimation by chromosome analysis was performed on the 3 severely exposed patients in the Tokai-mura criticality accident. Drastically reduced lymphocyte counts suggested that the whole-body dose of radiation which they had been exposed to was unprecedentedly high. Because the number of lymphocytes in the white blood cells in two patients was very low, we could not culture and harvest cells by the conventional method. To collect the number of lymphocytes necessary for chromosome preparation, we processed blood samples by a modified method, called the high-yield chromosome preparation method. With this technique, we could culture and harvest cells, and then make air-dried chromosome slides. We applied a new dose-estimation method involving an artificially induced prematurely condensed ring chromosome, the PCC-ring method, to estimate an unusually high dose with a short time. The estimated doses by the PCC-ring method were in fairly good accordance with those by the conventional dicentric and ring chromosome (Dic + R) method. The biologically estimated dose was comparable with that estimated by a physical method. As far as we know, the estimated dose of the most severely exposed patient in the present study is the highest recorded among that chromosome analyses have been able to estimate in humans. (author)

Oil Spill Detection and Modelling: Preliminary Results for the Cercal Accident

Science.gov (United States)

da Costa, R. T.; Azevedo, A.; da Silva, J. C. B.; Oliveira, A.

2013-03-01

Oil spill research has significantly increased mainly as a result of the severe consequences experienced from industry accidents. Oil spill models are currently able to simulate the processes that determine the fate of oil slicks, playing an important role in disaster prevention, control and mitigation, generating valuable information for decision makers and the population in general. On the other hand, satellite Synthetic Aperture Radar (SAR) imagery has demonstrated significant potential in accidental oil spill detection, when they are accurately differentiated from look-alikes. The combination of both tools can lead to breakthroughs, particularly in the development of Early Warning Systems (EWS). This paper presents a hindcast simulation of the oil slick resulting from the Motor Tanker (MT) Cercal oil spill, listed by the Portuguese Navy as one of the major oil spills in the Portuguese Atlantic Coast. The accident took place nearby Leix˜oes Harbour, North of the Douro River, Porto (Portugal) on the 2nd of October 1994. The oil slick was segmented from available European Remote Sensing (ERS) satellite SAR images, using an algorithm based on a simplified version of the K-means clustering formulation. The image-acquired information, added to the initial conditions and forcings, provided the necessary inputs for the oil spill model. Simulations were made considering the tri-dimensional hydrodynamics in a crossscale domain, from the interior of the Douro River Estuary to the open-ocean on the Iberian Atlantic shelf. Atmospheric forcings (from ECMWF - the European Centre for Medium-Range Weather Forecasts and NOAA - the National Oceanic and Atmospheric Administration), river forcings (from SNIRH - the Portuguese National Information System of the Hydric Resources) and tidal forcings (from LNEC - the National Laboratory for Civil Engineering), including baroclinic gradients (NOAA), were considered. The lack of data for validation purposes only allowed the use of the

Risk analysis of emergent water pollution accidents based on a Bayesian Network.

Science.gov (United States)