Decommissioning and dismantling reactors and managing waste

International Nuclear Information System (INIS)

Bensoussan, E.; Reicher-Fournel, N.

2005-01-01

In the early forties/fifties, a number of countries launched the first developments in the field of nuclear power. Some of them now have large numbers of nuclear facilities and nuclear power plants which have met, and continue to meet, the objectives for which they were designed and built. Other plants, including nuclear fuel production and enrichment plants, experimental reactors or research reactors, will have to be dismantled and demolished in the near future. These activities are handled differently in different countries as a function of specific energy policies, advanced development plants, current financial resources, the availability of qualified engineers and specialized industries able to handle projects of this kind, as well as other factors. All dismantling and demolition projects serve the purpose of returning the respective sites to green-field conditions. (orig.)

The Japan Power Demonstration Reactor dismantling project. Radiation control

International Nuclear Information System (INIS)

Tomii, Hiroyuki; Seiki, Yoshihiro

1996-01-01

In the Japan Power Demonstration Reactor (JPDR) dismantling project, radiation control was performed properly with routine and special monitoring to keep the occupational safety and to collect data necessary for future dismantling of nuclear facilities. This report describes a summary of radiation control in the dismantling activities and some results of parametric analysis on dose equivalent evaluation, and introduces the following knowledge on radiological protection effectiveness of the dismantling systems applied in the project. a) Use of remote dismantling systems was effective in reducing equivalent workplace exposure. b) Utilization of existing facilities as radiation shield or radioactivity containment was effective in reducing workplace exposure, and also in increasing work efficiency. c) Use of underwater cutting systems was useful to minimize air contamination, and to reduce the dose equivalent rate in the working area. d) In the planning of dismantling, it is necessary to optimize the radiation protection by analyzing dismantling work procedures and evaluating radiological features of the dismantling systems applied, including additional work which the systems require brought from such activities. (author)

Dismantling method for reactor shielding wall and device therefor

International Nuclear Information System (INIS)

Akagawa, Katsuhiko.

1995-01-01

A ring member having an outer diameter slightly smaller than an inner diameter of a reactor shielding wall to be dismantled is lowered in the inside of the reactor shielding wall while keeping a horizontal posture. A cutting device is disposed at the lower peripheral edge of the ring member. The cutting device can move along the peripheral edge of the circular shape of the ring member. The ring member is urged against the inner surface of the reactor shielding wall by using an urging member to immobilize the ring member. Then, the cutting device is operated to cut the reactor shielding wall into a plurality of ring-like blocks at a plurality of inner horizontal ribs or block connection ribs. Then, the blocks of the cut reactor shielding wall are supported by the ring member, and transported out of the reactor container by a lift. The cut blocks transported to the outside are finely dismantled for every block in a closed chamber. (I.N.)

A Study on Dismantling of Westinghouse Type Nuclear Reactor

International Nuclear Information System (INIS)

Jeong, Woo-Tae; Lee, Sang-Guk

2014-01-01

KHNP started a research project this year to develop a methodology to dismantle nuclear reactors and internals. In this paper, we reviewed 3D design model of the reactor and suggested feasible cutting scheme.. Using 3-D CAD model of Westinghouse type nuclear reactor and its internals, we reviewed possible options for disposal. Among various options of dismantling the nuclear reactor, plasma cutting was selected to be the best feasible and economical method. The upper internals could be segmented by using a band saw. It is relatively fast, and easily maintained. For cutting the lower internals, plasma torch was chosen to be the best efficient tool. Disassembling the baffle and the former plate by removing the baffle former bolts was also recommended for minimizing storage volume. When using plasma torch for cutting the reactor vessel and its internal, installation of a ventilation system for preventing pollution of atmosphere was recommended. For minimizing radiation exposure during the cutting operation, remotely controlled robotic tool was recommended to be used

Experience of partial dismantling and large component removal of light water reactors

International Nuclear Information System (INIS)

Dubourg, M.

1987-01-01

Not any of the French PWR reactors need to be decommissioned before the next decade or early 2000. However, feasibility studies of decommissioning have been undertaken and several dismantling scenarios have been considered including the dismantling of four PWR units and the on-site entombment of the active components into a reactor building for interim disposal. In addition to theoretical evaluation of radwaste volume and activity, several operations of partial dismantling of active components and decontamination activities have been conducted in view of dismantling for both PWR and BWR units. By analyzing the concept of both 900 and 1300 MWe PWR's, it appears that the design improvements taken into account for reducing occupational dose exposure of maintenance personnel and the development of automated tools for performing maintenance and repairs of major components, contribute to facilitate future dismantling and decommissioning operations

Cold trap dismantling and sodium removal at a fast breeder reactor

Energy Technology Data Exchange (ETDEWEB)

Graf, Anja; Petrick, Holger; Stutz, Uwe [WAK GmbH, Eggenstein-Leopoldshafen (Germany). Hauptabt. Dekontaminationsbetriebe Rueckbau Kompakte Natriumgekuehlte Kernreaktoranlage (KNK); Hosking, Paul [Nuclear Decommissioning Services Limited (NDSL), Sutherland, Dornoch (United Kingdom)

2013-11-15

The first German prototype Fast Breeder Nuclear Reactor (KNK) is currently being dismantled after being the only operating Fast Breeder-type reactor in Germany. As this reactor type used sodium as a coolant in its primary and secondary circuit, 7 cold traps containing various amounts of partially activated sodium needed to be disposed of as part of the dismantling. The resulting combined difficulties of radioactive contamination and high chemical reactivity were handled by treating the cold traps differently depending on their size and the amount of sodium contained inside. Six small cold traps were processed on-site by cutting them up into small parts using a band saw under a protective atmosphere. The sodium was then converted to sodium hydroxide by using water. The remaining large cold trap could not be handled in the same way due to its dimensions (2.9 m x 1.1 m) and the declared amount of sodium inside (1,700 kg). It was therefore manually dismantled inside a large box filled with a protective atmosphere, while the resulting pieces were packaged for later burning in a special facility. The experiences gained by KNK during this process may be advantageous for future dismantling projects in similar sodium-cooled reactors worldwide. (orig.)

Decommissioning of the BR3 pressurized-water reactor

International Nuclear Information System (INIS)

Massaut, V.

1996-01-01

The dismantling and the decommissioning of nuclear installations at the end of their life-cycle is a new challenge to the nuclear industry. Different techniques and procedures for the dismantling of a nuclear power plant on an existing installation, the BR-3 pressurized-water reactor, are described. The scientific programme, objectives, achievements in this research area at the Belgian Nuclear Research Centre SCK-CEN for 1995 are summarized

Progress in the development of tooling and dismantling methodologies for the Windscale advanced gas cooled reactor (WAGR)

International Nuclear Information System (INIS)

Cross, M.T.; Wareing, M.I.; Dixon, C.

1998-01-01

Decommissioning of the Windscale Advanced Gas-Cooled Reactor (WAGR) is a major UK reactor decommissioning project co-funded by the UK Government, the European Commission and Magnox Electric. WAGR was a CO 2 cooled, graphite moderated reactor which served as a test bed for the development of Advanced Gas-Cooled Reactor technology in the UK. It operated from 1963 until shutdown in 1981. AEA Technology plc are currently the Managing Agents on behalf of UKAEA for the WAGR decommissioning project and are responsible for the co-ordination of the project up to the point when the contents of the reactor core and associated radioactive materials are removed and either disposed of or packaged for disposal at some time in the future. Decommissioning has progressed to the point where the reactor has been dismantled down to the level of the hot gas collection manifold with the removal of the top biological shield, the refuelling standpipes and the top section of the reactor pressure vessel. The 4 heat exchangers have also been removed and committed to shallow land burial. This paper describes the work carried out by AEA Technology under separate contracts of UKAEA in developing some of the equipment and deployment methods for the next phase of active operations required in preparation for the dismantling of the core structure. Most recent work has concentrated on the development of specialist tooling for removal of items of operational waste stored within the reactor core, equipment for cutting and removal of the highly radioactive stainless steel 'loop' pressure tubes, diamond wire cutting equipment for sectioning large diameter pipework, and equipment for dismantling the reactor neutron shield. The paper emphasises the process of adaptation and extension of existing technologies for cost-effective application in the decommissioning environment, the need for adequate forward planning of decommissioning methodologies together with large-scale 'mock-up' testing of equipment to

Radioactivity, radiation protection and monitoring during dismantling of light-water reactors

International Nuclear Information System (INIS)

Hummel, L.; Zech, J.B.

2005-01-01

Based on the radioactivity inventory in the systems and components of light-water reactors observed during operation, the impact of actions during plant emptying after the conclusion of power operation and possible subsequent long-term safe enclosure concerning the composition of the nuclide inventory of the plant to be dismantled will be described. Derived from this will be the effects on radioactivity monitoring in the plant, physical radiation protection monitoring, and the measured characterization of the residual materials resulting from the dismantling. The impact of long-term interim storage will also be addressed in the discussion. The talk should provide an overview of the interrelationships between source terms, decay times and the radioactivity monitoring requirements of the various dismantling concepts for commercial light-water reactors. (orig.)

The dismantling of fast reactors: sodium processing

International Nuclear Information System (INIS)

Rodriguez, G.; Berte, M.; Serpante, J.P.

1999-01-01

Fast reactors require a coolant that does not slow down neutrons so water can not be used. Metallic sodium has been chosen because of its outstanding neutronic and thermal properties but sodium reacts easily with air and water and this implies that sodium-smeary components can not be considered as usual nuclear wastes. A stage of sodium neutralizing is necessary in the processing of wastes from fast reactors. Metallic sodium is turned into a chemically stable compound: soda, carbonates or sodium salts. This article presents several methods used by Framatome in an industrial way when dismantling sodium-cooled reactors. (A.C.)

Radiation exposure of the personnel during dismantling and cutting of the primary system of the Karlsruhe Multi-purpose Research Reactor (MZFR)

International Nuclear Information System (INIS)

Hesse, H.; Demant, W.; Reichert, A.; Willmann, F.

2000-10-01

The heavy water (D 2 O) cooled and moderated pressurized water reactor MZFR with a thermal power of 200 MW will be dismantled step-by-step within the framework of sectional decommissioning licenses. The past decommissioning step (6 th sectional license) in general covered the removal of the primary systems and of all reactor support systems inside the reactor building. The measures for radiation protection during dismantling and handling of the large components of the primary system, such as the fuel element loading machine, fuel element transfer system, steam generator and pressurizer shall be pointed out. The measures taken for the reduction of the dose rate during dismantling and cutting of the components for the purpose of conditioning or unrestricted reuse at the central decontamination department (HDB) shall be described. Chemical decontamination of the primary circuit and its components, which had to be executed in order to reduce the dose rates for subsequent manual dismantling, shall be presented. The efforts undertaken for the protection of individuals in view of the difficult radiological boundary conditions (high concentrations of tritium in all systems as well as very high alpha contamination) will be explained. Moreover, dose-minimizing measures during cutting of the primary circuit and its components at HDB shall be described by the example of the cutting of a steam generator. It shall be demonstrated that cutting and dismantling of highly contaminated and activated parts with high dose rates can be executed safely in terms of both the radiation exposure of the personnel and the technical, financial and time expenditure. (orig.)

Dismantling of JPDR reactor internals by underwater plasma arc cutting technique using robotic manipulator

International Nuclear Information System (INIS)

Yokota, M.

1988-01-01

The actual dismantling of JPDR started on December 4, 1986. As of now, equipment that surrounds the reactor has mostly been removed to provide working space in reactor containment prior to the dismantling of reactor internals. Some reactor internals have been successfully dismantled using the underwater arc cutting system with a robotic manipulator during the period of January to March 1988. The cutting system is composed of an underwater plasma arc cutting device and a robotic manipulator. The cut off reactor internals were core spray block, feedwater sparger and stabilizers for fuel upper grid tube. The plasma arc cutting device was developed to dismantle the reactor internals underwater. It mainly consists of a plasma torch, power and gas supply systems for the torch, and by-product treatment systems. It has the cutting ability of 130 mm thickness stainless steel underwater. The robotic manipulator has seven degrees of freedom of movement, enabling it to move in almost the same way as the arm of a human being. The arm of the robot is mounted on a supporting device which is suspended by three chains from the support structure set on a service floor. A plasma torch is griped by the robotic hand; its position to the structure to be cut is controlled from a remote control room, about 100 meters outside the reactor containment

Challenges of dismantling

International Nuclear Information System (INIS)

Chevet, P.F.; Schilz, F.; Rondeau, J.M.; Piketty, L.; Dupraz, B.; Conte, D.; Duguey, M.; Louet, C.A.; Dorison, A.; Dutzer, M.; Boucau, J.; Eimer, M.; Boutin, D.; Revilla, J.L.; Golshan, M.; Smith, G.

2015-01-01

This document is made up of short articles whose issue is reactor dismantling. The first article presents the French strategy that can be featured by immediate dismantling (the dismantling process is prepared a long time before decommissioning and begins as soon as the reactor is shut down) and massive dismantling (a lot of nuclear facilities will be decommissioned in a near future). The following 4 articles give the viewpoints of ASN (Nuclear Safety Authority), EDF (for its fleet of PWRs), CEA (for its experimental reactors and nuclear facilities) and AREVA (for the EURODIF George Besse plant). Costs and financing are dealt with in an article that says that the cost is greatly dependent on the final state: a complete nuclear-free area or an area whose radioactivity is below safe standards and that law implies to constitute provisions all along the operating life of the facility to cover dismantling costs. Dismantling generates a huge amount of very low-level radioactive wastes particularly metal scraps that might be recycled and get out of nuclear industry, an article details the feasibility of such recycling. Another article shows the impact of massive dismantling on the management of radioactive wastes. In an article Westinghouse presents its experience in the cutting of internal equipment of the reactor core. The last 2 articles presents the dismantling strategies in Spain and in the UK. (A.C.)

General plan for the partial dismantling of the IRT-Sofia research reactor

Directory of Open Access Journals (Sweden)

Apostolov Tihomir G.

2006-01-01

Full Text Available After the decision of the Bulgarian Government to reconstruct it, the strategy concerning the IRT-Sofia Research Reactor is to partially dismantle the old systems and equipment. The removal of the reactor core and replacement of old equipment will not pose any significant problems. For a more efficient use of existing resources, there is a need for an engineering project which has been already prepared under the title "General Plan for the Partial Dismantling of Equipment at the IRT-Sofia as a Part of the Reconstruction into a Low Power RR".

How to replace a reactor pressure vessel

International Nuclear Information System (INIS)

Huber, R.

1996-01-01

A potential life extending procedure for a nuclear reactor after, say, 40 years of service life, might in some circumstances be the replacement of the reactor pressure vessel. Neutron induced degradation of the vessel might make replacement by one of a different material composition desirable, for example. Although the replacement of heavy components, such as steam generators, has been possible for many years, the pressure vessel presents a much more demanding task if only because it is highly irradiated. Some preliminary feasibility studies by Siemens are reported for the two removal strategies that might be considered. These are removal of the entire pressure vessel in one piece and dismantling it into sections. (UK)

Stage 2: dismantling of reactor case of the experimental F.B.R. Rapsodie

International Nuclear Information System (INIS)

Roger, J.

1994-01-01

This document defines the main objectives of stage 2 dismantling of the Rapsodie experimental fast neutron reactor and specifies its time schedule. The work already in progress consists in containing the reactor vessel and its internal equipment, as well as the neutron protection concrete, inside the two leak-tight barriers, and in dismantling all the systems and equipment systems contaminated by sodium. This work, which includes the destruction of 37 metric tons of contaminated sodium from the primary system, was begun in 1987 and will be completed in 1994. The duration of the waiting period for complete dismantling (stage 3) has not been defined. However, the containment and monitoring means implemented should allow a safe waiting period of several decades. (author). 4 figs

Deliberated opinion of the Environment Authority concerning the dismantling of the Ulysse reactor (CEA Saclay)

International Nuclear Information System (INIS)

2010-01-01

As the Ulysse reactor of Saclay is about to be dismantled, this report discusses the content of a request made by the CEA to definitely stop and dismantle this reactor. After having recalled the origin of this dismantling project and its regulatory framework, it describes the actual works which are planned, and outlines the main challenges to be faced. It discusses the content of the environmental report or impact study, notably the analysis of the initial condition, the analysis of direct and indirect effects of the project on the environment and health, and of the envisaged measures (waste management, liquid and gaseous effluent management, risk management, radiological exposure of workers in charge of this dismantling, and transports). Recommendations are formulated for a rewriting of the provided documents

Project WAGR: the UK demonstration project for power reactor decommissioning - a review of the tools used to dismantle the reactor core

International Nuclear Information System (INIS)

Benest, T.G.

2008-01-01

The United Kingdom Atomic Energy Authority (UKAEA) has built and operated a wide range of nuclear facilities since the late 1940. UKAEA mission is to restore the environment of its sites in a safe and secure manner. This restoration includes the decommissioning of a number of redundant research and power reactors. The Windscale Advanced Gas-cooled Reactor (WAGR) was the UK prototype Advanced gas cooled reactor and became the forerunner of a family of 14 reactors built to generate cheaper and more efficient electricity in the UK. WAGR was constructed between 1957 and 1961 and was a carbon dioxide cooled, graphite moderated reactor using uranium oxide fuel in stainless steel cans. The reactor consisted of a graphite moderator housed in a cylindrical reactor vessel with hemispherical ends. The reactor and associated heat exchangers were enclosed in the iconic spherical containment building regularly used by the media in the UK as an illustration of the nuclear industry. The reactor first produced power in August 1962 and achieved full design output in 1963. It operated at an electrical output of 33 MW (E) for 18 years (average load factor of 75%). In 1981 the reactor was shut down after satisfactory completion of all the research and development objectives. In anticipation of the UK likely nuclear decommissioning needs the UKAEA decided to decommission WAGR to the International Atomic Energy Agency (IAEA) stage 3 (restoration of the area occupied by the facility to a condition of unrestricted re-usability) as the national demonstration exercise for power reactor decommissioning. Since 1998 the UKAEA and its contractors have been undertaking the dismantling of the reactor core components and pressure vessel in a series of 10 campaigns. These contain neutron activated components expected to produce dose rates well in excess of 1 Sv/hr. To carry out the work UKAEA installed an 8M remote dismantling machine (RDM) a waste recovery and transport system and a shielded waste

Dismantling of JPDR begins: to demonstrate advanced technology

Energy Technology Data Exchange (ETDEWEB)

1986-12-01

The first dismantling of the Japan Power Demonstration Reactor (JPDR, BWR, 90 MWt, 12.5 MWe) began on December 4, 1986, claiming the attention of nuclear interests in Japan and overseas. The Japan Atomic Energy Research Institute undertook the project as the second phase of the six year program for dismantling the JPDR at the Tokai Research Establishment. It is the demonstration of the technology developed in the first phase of the program from 1981 to 1986, aiming at establishing a total system for dismantling commercial nuclear power plants in the furture. At the ceremony for the beginning of dismantling held on December 4 at the site, a special switch was operated to fire a gas burner, and cutting of the upper head of the reactor pressure vessel on the service floor of the reactor building began. The long term program on the development and utilization of nuclear energy in 1982 decided the basic policy on reactor decommissioning. Under this policy, in July, 1984, the nuclear subcommittee of the Advisory Committee for Energy set up the guideline for standardized decommissioning suitable to the actual situation in Japan. The schedule of the program, the development of eight fundamental techniques, disassembling techniques, decontamination, measurement and robotics are described. (Kako, I.).

Method of dismantling a nuclear reactor

International Nuclear Information System (INIS)

Shirai, Masato; Hashimoto, Osamu.

1984-01-01

Purpose: To enable rapid and simple positioning for a plasma arc torch disposed to the inside of a nuclear reactor main body. Method: After removing the upper semi-spherical portion, fuel portion and control rod portion of a nuclear reactor, a rotary type girder is placed on the upper edge of a cylindrical portion remained after the removal of the upper semi-spherical portion. Then, the upper portion of a supporting rod provided with a swing arm having a plasma arc torch at the top end is situated at the center of the reactor main body. Then, the top end of the support rod is inserted to fix in the housing of control rod drives. Then, the swing arm is actuated to situate the plasma arc torch to a desired position to be cut, whereafter cutting is initiated while rotating the rotary type girder. Thus, plasma arc torch is moved horizontally along an arcuate trace, whereby pipeways, accessories or the likes disposed to the inside of the main body are at first cut and then the cylindrical portion constituting the main body is cut to dismantle the reactor. (Moriyama, K.)

Remote techniques for the underwater dismantling of reactor internals at the nuclear power plant Gundremmingen unit A

International Nuclear Information System (INIS)

Eickelpasch, N.; Steiner, H.; Priesmeyer, U.

1997-01-01

Unit A of the nuclear power plant in Gundremmingen (KRB A) is a boiling water reactor with an electrical power of 250 MWe. It was shut down in 1977 after eleven years of operation. The actual decommissioning started in 1983. Since then more than 5200 tons of contaminated components have been dismantled. Special cutting and handling tools were tested, developed and optimized for the purpose of working in radiation fields and under water. Due to the special design of KRB A, which uses a dual-cycle system for additional steam generation, the experience gained is transferable to pressurized water reactors. (Author)

Data analysis on work activities in dismantling of Japan Power Demonstration Reactor (JPDR). Contract research

International Nuclear Information System (INIS)

Shiraishi, Kunio; Sukegawa, Takenori; Yanagihara, Satoshi

1998-03-01

The safe dismantling of a retired nuclear power plant was demonstrated by completion of dismantling activities for the Japan Power Demonstration Reactor (JPDR), March, 1996, which had been conducted since 1986. This project was a flag ship project for dismantling of nuclear power plants in Japan, aiming at demonstrating an applicability of developed dismantling techniques in actual dismantling work, developing database on work activities as well as dismantling of components and structures. Various data on dismantling activities were therefore systematically collected and these were accumulated on computer files to build the decommissioning database; dismantling activities were characterized by analyzing the data. The data analysis resulted in producing general forms such as unit activity factors, for example, manpower need per unit weight of component to be dismantled, and simple arithmetic forms for forecasting of project management data to be applied to planning another dismantling project through the evaluation for general use of the analyzed data. The results of data analysis could be usefully applied to planning of future decommissioning of commercial nuclear power plants in Japan. This report describes the data collection and analysis on the JPDR dismantling activities. (author)

Safe dismantling of the SVAFO research reactors R2 and R2-0 in Sweden

International Nuclear Information System (INIS)

ARNOLD, Hans-Uwe; BROY, Yvonne; Dirk Schneider

2017-01-01

The R2 and R2-0 reactors were part of the Swedish government's research program on nuclear power from the early 1960's. Both reactors were shut down in 2005 following a decision by former operator Studsvik Nuclear AB. The decommissioning of the R2 and R2-0 reactors is divided into three phases. The first phase - awarded to AREVA - involved dismantling of the reactors and associated systems in the reactor pool, treatment of the disassembled components as well as draining, cleaning and emptying the pool. In the second phase, the pool structure itself will be dismantled, while removal of remaining reactor systems, treatment and disposal of materials and clean-up will be carried out in the third stage. The entire work is planned to be completed before the end of this decade. The paper describes the several steps of phase 1 - starting with the team building, followed by the dismantling operations and covers challenges encountered and lessons learned as well. The reactors consist of 5.400 kg aluminum, 6.000 kg stainless steel restraint structures as well as, connection elements of the mostly flanged components (1.000 kg). The most demanding - from a radiological point of view - was the R2-0 reactor that was limited to ∼ 1 m"3 construction volumes but with an extremely heterogeneous activation profile. Based on the calculated radiological entrance data and later sampling, nuclide vectors for both reactors depending on the real placement of the single component and on the material (aluminum and stainless steel) were created. Finally, for the highest activated component from R2 reactor, 85 Sv/h were measured. The dismantling principles - adopted on a safety point of view - were the following: The always protected base area of the ponds served as a flexible buffer area for waste components and packaging. Specific protections were also installed on the walls to protect them from mechanical stress which may occur during dismantling work. A specific work platform was

Dismantling of the reactor block of the FRJ-1 research reactor (MERLIN); Abbau des Reaktorblocks des Forschungsreaktors FRJ-1 (MERLIN)

Energy Technology Data Exchange (ETDEWEB)

Stahn, B.; Matela, K.; Zehbe, C. [Forschungszentrum Juelich GmbH (Germany); Poeppinghaus, J. [Gesellschaft fuer Nuklear-Service mbH, Essen (Germany); Cremer, J. [Siempelkamp Nukleartechnik GmbH, Heidelberg (Germany)

2003-07-01

By the end of 1998 the complete secondary cooling system and the major part of the primary cooling system were dismantled. Furthermore, the experimental devices, including a rabbit system conceived as an in-core irradiation device, were disassembled and disposed of. In total, approx. 65 t of contaminated and/or activated material as well as approx. 70 t of clearance-measured material were disposed of within the framework of these activities. The dismantling of the coolant loops and experimental devices was followed in 2000 by the removal of the reactor tank internals and the subsequent draining of the reactor tank water. The reactor tank internals were essentially the core support plate, the core box, the flow channel and the neutron flux bridges (s. Fig. 2, detailed reactor core). All components consisted of aluminium, the connecting elements such as bolts and nuts, however, of stainless steel. Due to the high activation of the core internals, disassembly had to be remotely controlled under water. All removal work was carried out from a tank intermediate floor (s. Fig. 2). These activities, which served for preparing the dismantling of the reactor block, were completed in summer 2001. The waste parts arising were transferred to the Service Department for Decontamination of the Research Centre. This included approx. 2.5 t of waste parts with a total activity of approx. 8 x 10{sup 11} Bq. (orig.)

Characterization of radioactive graphite and concrete of the reactor ULYSSE/INSTN at CEA/Saclay to be dismantled

International Nuclear Information System (INIS)

Van Lauwe, Aymeric; Ridikas, Danas; Damoy, Francois; Blideanu, Valentin; Fajardo, Christophe; Aubert, Marie-Cecile; Foulon, Francois

2006-01-01

Decommissioning and dismantling of nuclear installations after their service life are connected with the necessity of the disassembling, handling and disposing of a large amount of radioactive material. In order to optimize the disassembling operations, to reduce the undesirable volume to the minimum and to successfully plan the dismantling and disposal of radioactive materials to storage facilities, the radiological characterisation of the material present in the reactor and around its environment should be accurately evaluated. The present work has been done in the framework of the decommissioning and dismantling of the experimental reactor ULYSSE that is presently operating in INSTN/Saclay and will be closed in the middle of 2006. A methodology, already successfully used for another research reactor, is proposed for determining accurately the long-term induced activity of the materials present in the active reactor core and its surroundings. The comparison of theoretical predictions, based on Monte Carlo technique, with experimental values validated the approach and the methodology used in the present study. The goal is to plan efficiently the disassembling and dismantling of the system and to optimise the mass flow going to different waste repositories. We show that this approach might reduce substantially the total cost of decommissioning. (authors)

Clearance of radioactive materials during reactor dismantling. Permanent enclosure instead of demolition and renaturation?

International Nuclear Information System (INIS)

2016-01-01

During reactor dismantling besides high-level radioactive wastes a large amount of low-level contaminated steel and concrete has to be disposed. In case that radioactivity falls below defined dose limits (10 micro Sv/person and year) these materials may be disposed in domestic waste landfill or in municipal incineration facilities. The issue is discussed in detail including the fact that many power plants are dismantled at the same time so that the contaminated materials might accumulate. Another issue is the occupational safety of contract workers during dismantling. The permanent enclosure could avoid this environmental contamination of decommissioned power plants might also be less expensive.

Using SAFRAN Software to Assess Radiological Hazards from Dismantling of Tammuz-2 Reactor Core at Al-tuwaitha Nuclear Site

Science.gov (United States)

Abed Gatea, Mezher; Ahmed, Anwar A.; jundee kadhum, Saad; Ali, Hasan Mohammed; Hussein Muheisn, Abbas

2018-05-01

The Safety Assessment Framework (SAFRAN) software has implemented here for radiological safety analysis; to verify that the dose acceptance criteria and safety goals are met with a high degree of confidence for dismantling of Tammuz-2 reactor core at Al-tuwaitha nuclear site. The activities characterizing, dismantling and packaging were practiced to manage the generated radioactive waste. Dose to the worker was considered an endpoint-scenario while dose to the public has neglected due to that Tammuz-2 facility is located in a restricted zone and 30m berm surrounded Al-tuwaitha site. Safety assessment for dismantling worker endpoint-scenario based on maximum external dose at component position level in the reactor pool and internal dose via airborne activity while, for characterizing and packaging worker endpoints scenarios have been done via external dose only because no evidence for airborne radioactivity hazards outside the reactor pool. The in-situ measurements approved that reactor core components are radiologically activated by Co-60 radioisotope. SAFRAN results showed that the maximum received dose for workers are (1.85, 0.64 and 1.3mSv/y) for activities dismantling, characterizing and packaging of reactor core components respectively. Hence, the radiological hazards remain below the low level hazard and within the acceptable annual dose for workers in radiation field

Decommissioning, Dismantling and Disarming: a Unique Information Showroom Inside the G2 Reactor at Marcoule Centre (France) - 12068

Energy Technology Data Exchange (ETDEWEB)

Volant, Emmanuelle [CEA DAM, Bruyeres-le-Chatel (France); Garnier, Cedric [CEA DEN, Marcoule (France)

2012-07-01

The paper aims at presenting the new information showroom called 'Escom G2' (for 'Espace Communication') inaugurated by the French Atomic Energy and Alternative Energies Commission (CEA) in spring 2011. This showroom is settled directly inside the main building of the G2 nuclear reactor: a facility formerly dedicated to weapon-grade plutonium production since the late 1950's at the Marcoule nuclear centre, in south of France. After its shutdown, and reprocessing of the last spent fuels, a first dismantling step was successfully completed from 1986 to 1996. Unique in France and in Europe, Escom G2 is focused on France dismantling expertise and its action for disarmament. This showroom comprises of a 300-square meters permanent exhibition, organized around four themes: France strategy for disarmament, decommissioning and dismantling technical aspects, uranium and plutonium production cycles. Each of these topics is illustrated with posters, photos, models and technical pieces from the dismantled plants. It is now used to present France's action in disarmament to highly ranked audiences such as: state representatives, diplomats, journalists... The paper explains the background story of this original project. As a matter of fact, in 1996 France was the first nuclear state to decide to shut down and dismantle its fissile material production facilities for nuclear weapons. First, the paper presents the history of the G2 reactor in the early ages of Marcoule site, its operating highlights as well as its main dismantling operations, are presented. In Marcoule, where the three industrial-scale reactors G1, G2 and G3 used to be operated for plutonium production (to be then reprocessed in the nearby UP1 plant), the initial dismantling phase has now been completed (in 1980's for G1 and in 1996 for G2 and G3). The second phase, aimed at completely dismantling these three reactors, will restart in 2020, and is directly linked to the opening of

Technology, safety, and costs of decommissioning a reference pressurized water reactor power station

International Nuclear Information System (INIS)

Smith, R.I.; Konzek, G.J.; Kennedy, W.E. Jr.

1978-05-01

Safety and cost information was developed for the conceptual decommissioning of a large [1175 MW(e)] pressurized water reactor (PWR) power station. Two approaches to decommissioning, Immediate Dismantlement and Safe Storage with Deferred Dismantlement, were studied to obtain comparisons between costs, occupational radiation doses, potential radiation dose to the public, and other safety impacts. Immediate Dismantlement was estimated to require about six years to complete, including two years of planning and preparation prior to final reactor shutdown, at a cost of $42 million, and accumulated occupational radiation dose, excluding transport operations, of about 1200 man-rem. Preparations for Safe Storage were estimated to require about three years to complete, including 1 1 / 2 years for planning and preparation prior to final reactor shutdown, at a cost of $13 million and an accumulated occupational radiation dose of about 420 man-rem. The cost of continuing care during the Safe Storage period was estimated to be about $80 thousand annually. Accumulated occupational radiation dose during the Safe Storage period was estimated to range from about 10 man-rem for the first 10 years to about 14 man-rem after 30 years or more. The cost of decommissioning by Safe Storage with Deferred Dismantlement was estimated to be slightly higher than Immediate Dismantlement. Cost reductions resulting from reduced volumes of radioactive material for disposal, due to the decay of the radioactive containments during the deferment period, are offset by the accumulated costs of surveillance and maintenance during the Safe Storage period

UDIN's dismantling projects

International Nuclear Information System (INIS)

Laffaille, C.

1993-01-01

The role of UDIN (Central unit for nuclear facility decommissioning) at the CEA is reviewed together with the main specific aspects of nuclear dismantling: the different options and dismantling strategies and costs. The characteristics of the main on-going projects are described: graphite-gas reactors (G2/G3), RAPSODIE (RNR), AT1 (pilot RNR fuel reprocessing plant), ELAN II B (Cesium source conditioning plant), EL4 (heavy water/CO2 reactor), RM2 (fuel control radio-metallurgical laboratory) and UB-UM (Uranium enrichment plant)

Robotic dismantlement systems at the CP-5 reactor D and D project

International Nuclear Information System (INIS)

Seifert, L. S.

1998-01-01

The Chicago Pile 5 (CP-5) Research Reactor Facility is currently undergoing decontamination and decommissioning (D and D) at the Argonne National Laboratory (ANL) Illinois site. CP-5 was the principle nuclear reactor used to produce neutrons for scientific research at Argonne from 1954 to 1979. The CP-5 reactor was a heavy-water cooled and moderated, enriched uranium-fueled reactor with a graphite reflector. The CP-5 D and D project includes the disassembly, segmentation and removal of all the radioactive components, equipment and structures associated with the CP-5 facility. The Department of Energy's Robotics Technology Development Program and the Federal Energy Technology Center, Morgantown Office provided teleoperated, remote systems for use in the dismantlement of the CP-5 reactor assembly for tasks requiring remote dismantlement as part of the EM-50 Large-Scale Demonstration Program (LSDP). The teleoperated systems provided were the Dual Arm Work Platform (DAWP), the Rosie Mobile Teleoperated Robot Work System (ROSIE), and a remotely-operated crane control system with installed swing-reduction control system. Another remotely operated apparatus, a Brokk BM250, was loaned to ANL by the Princeton Plasma Physics Laboratory (PPPL). This machine is not teleoperated and was not part of the LSDP, but deserves some mention in this discussion. The DAWP is a robotic dismantlement system that includes a pair of Schilling Robotic Systems Titan III hydraulic manipulator arms mounted to a specially designed support platform: a hydraulic power unit (HPU) and a remote operator console. The DAWP is designed to be crane-suspended for remote positioning. ROSIE, developed by RedZone Robotics, Inc. is a mobile, electro-hydraulic, omnidirectional platform with a heavy-duty telescoping boom mounted to the platform's deck. The work system includes the mobile platform (locomotor), a power distribution unit (PDU) and a remote operator console. ROSIE moves about the reactor building

Experience of the remote dismantling of the Windscale advanced gas-cooled reactor and Windscale pile chimneys

International Nuclear Information System (INIS)

Wright, E.M.

1993-01-01

This paper gives brief descriptions of some of the remote dismantling work and equipment used on two large decommissioning projects: the BNFL Windscale Pile Chimneys Project (remote handling machine, waste packaging machine, remotely controlled excavator, remotely controlled demolition machine) and the AEA Windscale Advanced Gas-cooled Reactor Project (remote dismantling machine, operational waste, bulk removal techniques, semi-remote cutting operations)

Remote dismantlement tasks for the CP5 reactor: Implementation, operations, and lessons learned

International Nuclear Information System (INIS)

Noakes, M.W.

1998-01-01

This paper presents a developer's perspective on lessons learned from one example of the integration of new prototype technology into a traditional operations environment. The dual arm work module was developed by the Robotics Technology Development Program as a research and development activity to examine manipulator controller modes and deployment options. It was later reconfigured for the dismantlement of the Argonne National Laboratory Chicago Pile number-sign 5 reactor vessel as the crane-deployed dual arm work platform. Development staff worked along side operations staff during a significant part of the deployment to provide training, maintenance, and tooling support. Operations staff completed all actual remote dismantlement tasks. At the end of available development support funding, the Dual Arm Work Platform was turned over to the operations staff, who is still using it to complete their dismantlement tasks

Evaluation formulas of manpower needs for dismantling of equipment in FUGEN-3. Dismantling process of the condenser removal

International Nuclear Information System (INIS)

Kubota, Shintaro; Izumo, Sari; Usui, Hideo; Kawagoshi, Hiroshi; Koda, Yuya; Nanko, Takashi

2014-07-01

Japan Atomic Energy Agency (JAEA) has been developing the PRODIA code which supports to make decommissioning plan and has been preparing evaluation formulas. Manpower needs for the dismantling of the condenser that had conducted from 2010 to 2012 was analyzed and compared with existing evaluation formulas. Applicability of evaluation formulas for a large scale reactor facility was confirmed in dismantling of the heat insulating materials and reliability of unit productivity factor was improved. The evaluation formula of work for clearance was made in dismantling of pipes and supports. Unit productivity factor of dismantling of feed water heaters which is applicable for a large scale reactor facility was derived. For derivation of unit productivity factor, statistically meaningful data was provided from the dismantling of the condenser. Manpower needs for dismantling of the condenser has positive correlation to the weight of equipment and can be described in linear expression. Reliability of each unit productivity factor will be improved with accumulating actual dismantling data in future. (author)

Dismantling of nuclear facilities: the industrial know-how

International Nuclear Information System (INIS)

Lellament, R.

2004-01-01

Numerous nuclear facilities in laboratories or research reactors have been decommissioned and dismantled over the 2 last decades throughout the world. The valuable feedback experience has allowed nuclear industry to design, upgrade and test specific techniques for dismantling. These techniques are efficient although they have been validated on a reduced number of nuclear power plants. In France only 3 power units have been dismantled: Chinon A1, A2 and Brennilis (EL4) and they are not representative of the real park of EDF'reactors. 6 PWR-type reactors have already been dismantled in the Usa. The results of a survey concerning 26 countries shows that the dismantling cost is around 320 dollars/kWe, it represents 15% of the construction cost which is far from being excessive as it is often read in the media. The dismantling costs can be broken into: - de-construction (25-55%), - wastes from dismantling (17-43%), - security and monitoring (8-13%), - site reclamation (5-13%), and - engineering and project management (5-24%). (A.C.)

Assessment of the applicability of AWJ technique for dismantling the reactor of Fugen. Performance of underwater-cutting thick plate and testing of sound-based monitoring for underwater-cutting process

International Nuclear Information System (INIS)

Maruyama, Shin-ichiro; Nishio, Shin-ichi

2010-01-01

The reactor of Fugen is characterized by its double-walled pressure tube construction that is composed of pressure tubes and calandria tubes. The reactor dismantlement has been planning on dismantling it under water and the abrasive water jet (AWJ) underwater-cutting method is chosen as an option among simultaneous double tubes cutting technologies. For assessing the applicability of the AWJ cutting technology, a thick plate was cut under water by the small AWJ cutting machine. In addition, since cutting causes muddiness in water, cutting was monitored by the sound-based monitoring system which was adopted as a secondary cutting monitoring method. As a results, it was demonstrated that one-phase cutting was possible under water for a stainless-steel plate with 150mm thickness and that the relationship between cutting depth and capable cutting speed could be predictable. As for the sound-based cutting monitoring, the predictability whether or not cutting would be successful was verified by checking the change of sounds level. (author)

The Superphenix dismantling

International Nuclear Information System (INIS)

Carle, R.

1999-01-01

This document presents selected abstracts of Remy Carle's presentation on the dismantling of Superphenix (october 1998). The author wonders about the consequences of such a decision. After a chronological account of this fast reactor project, its cost and the scientific and technical contribution, the dismantling problem is considered. For EDF (Electricite De France) the dismantling dimension is considered at the same time of the design. The main problem is the liquid sodium reprocessing: a technical but also a financing problem. The end of the speech deals with the political aspects of Superphenix and the relations with the public. (A.L.B.)

Cleansing and dismantling of CEA-Saclay nuclear licensed facilities

International Nuclear Information System (INIS)

Jeanjacques, Michel; Delaire, Isabelle; Glevarec, Rebecca; Mandard, Lionel; Martin, Jean-Louis; Serrano, Roger

2013-01-01

This summary presents the cleansing and dismantling operations currently realized on the CEA center of Saclay (CEA-Saclay). It was initiated at the beginning of the 2000 years a cleansing and dismantling program of the old Nuclear Licensed Facilities (NLF). Currently this program relates the dismantling operations to the Hot Laboratories (Laboratoires de Haute Activite: LHA) and the old workshops of the Liquid Waste Treatment Plant (Station des Effluents Liquides: STEL), the dismantling preparation of Ulysse reactor and the dismantling studies to the Solid Waste Management Plant (SWMP; Zone de Gestion des Dechets Solides) and the Osiris reactor. (authors)

The good wealth of dismantlement

International Nuclear Information System (INIS)

Maincent, G.

2009-01-01

Civil engineering, mechanical and waste conditioning companies are working hard on the market of nuclear facilities dismantling. This market has a great future ahead of it in the ten years to come. According to the European Commission, 50 to 60 reactors among the 157 actually in service in the European Union should be dismantled by 2025. The cost per reactor is estimated to 10-15% of the initial investment, which represents an enormous amount of money, estimated to 20-39 billion euros for the only French nuclear park. In France, this market is shared by a core of about 20 companies, like Spie Nucleaire, Onet, Vinci (Nuvia) and Areva. Some dismantling sites require a specific skill, in particular those in relation with the research activity of the CEA (the French atomic energy commission) or involving specific technologies (research reactors, spent fuel reprocessing plants, sodium-cooled rectors..). (J.S.)

Taking into account of dismantling constraints in the design of nuclear facilities

International Nuclear Information System (INIS)

Gouhier, E.; Moitrier, C.; Girones, P.; Pitrou, Y.; Poncet, P.; O'Sullivan, P.

2014-01-01

The taking into account of dismantling constraints in the design of nuclear facilities allows the reduction of the dosimetry during the dismantling operations, the reduction of the amount of wastes to manage and the saving of time and money by foreseeing an adequate and simple solution for each component. It is to notice that the strategy of life-extension strengthens that of dismantling because life-extension implies the possibility for any component of the reactor except the pressure vessel to be replaced. The feedback experience capitalized on various types of nuclear facilities have enabled IAEA and OECD to publish recommendations to facilitate dismantling. For instance, pipes and ventilation ducts must be designed to minimize the deposit of dust and residues, the natural porosity of concrete must be limited through the use of polishing products or a metal liner, the type and concentrations of impurities present in the structure materials must be controlled to limit radioactivation, the documentation describing the facility must be kept up to date, or the history of contamination events must be recorded all along the life of the facility. The integration of the dismantling constraints in the design stage is illustrated with 3 examples: the Georges Besse 2 enrichment fuel plant, new reactors (EPR, ASTRID and RJH), and ITER. (A.C.)

Dismantling large components at the Jose-Cabrera NPP (CNJC) in Spain

International Nuclear Information System (INIS)

Santiago, Juan Luis

2012-01-01

Located in central Spain, near Madrid, the Jose-Cabrera NPP (also known as Zorita) is the first PWR to be dismantled in Spain. The unit is a one-loop Westinghouse PWR, with a capacity of 150 MW. The plant was shut down in 1996 and ENRESA (Empresa Nacional de Residuos Radioactivos) has decided its prompt decommissioning, starting in 2010. In preparation for decommissioning, a full system decontamination (FSD) of the whole reactor cooling system (including the reactor vessel in the flow path) was carried out in 2006-7. The large components to be dismantled include: the reactor pressure vessel (RPV) and the internals; the vessel head; the SG; the pressurizer and the surge line; the reactor coolant pump, and the primary loop piping The objective of the project is not only to ensure the safe and efficient dismantling of those large components, but also to gain experience and to learn lessons to be applied during the future decommissioning and dismantling of the remaining six operating PWRs in Spain, whose operational lives are currently planned to end between 2021 and 2028. ENRESA has defined a waste-management policy for decommissioning activities, which includes Waste-management routes and optimisation. A case study describes the results obtained by ENRESA in the specific case of CNJC large components (including the RPV) dismantling project: Removal and conditioning of large components as a single piece is not considered a viable option. Segmentation therefore is required and 2 options have been analysed: large pieces for disposal in a large container and small pieces for disposal in approved concrete packages (CE-2a and the smaller CE-2b). The use of the CE-2b package is a feasible option and is easy to implement as a logical extension from the CE-2a. The use of the CE-2b package results in an important reduction in the total volume of final waste packages and does not require, in itself, any changes in the current waste handling and kinematics. The large size

The Japan Power Demonstration Reactor (JPDR) dismantling activities. Dismantling of the reactor enclosure and the auxiliary buildings

International Nuclear Information System (INIS)

Seiki, Yoshihiro; Kubo, Takashi.

1996-01-01

As the final stage of the JPDR decommissioning program, after the major components were removed from each building of JPDR, the dismantling activities proceeded to the decontamination of contaminated concrete surface and the final radiation survey of buildings. These activities were conducted to verify the developed techniques and the detailed procedures for decontamination, and to allow unrestricted use of the JPDR buildings. Following the decontamination of buildings, the dismantling of each building was started. Before dismantling the buildings, the radiation control designations were changed. The buildings that contaminated embedded pipes were changed from first-class radiation controlled areas to second-class radiation controlled areas. On the other hand, the buildings that had no contaminated pipes were changed to uncontrolled areas. A first-class radiation controlled area allows the use of unsealed sources ; thus, radioactive contamination may exist. A second-class radiation controlled area is one where only sealed sources are allowed. Significant quantities of data and experience were obtained during these activities. The practical procedures for decontamination, the final survey of radioactivity, and the dismantling work of buildings were described in this report. (author)

The Molten Salt Reactor option for beneficial use of fissile material from dismantled weapons

International Nuclear Information System (INIS)

Gat, U.; Engel, J.R.; Dodds, H.L.

1991-01-01

The Molten Salt Reactor (MSR) option for burning fissile fuel from dismantled weapons is examined. It is concluded that MSRs are very suitable for beneficial utilization of the dismantled fuel. The MSRs can utilize any fissile fuel in continuous operation with no special modifications, as demonstrated in the Molten Salt Reactor Experiment. Thus MSRs are flexible while maintaining their economy. MSRs further require a minimum of special fuel preparation and can tolerate denaturing and dilution of the fuel. Fuel shipments can be arbitrarily small, all of which supports nonproliferation and averts diversion. MSRs have inherent safety features which make them acceptable and attractive. They can burn a fuel type completely and convert it to other fuels. MSRs also have the potential for burning the actinides and delivering the waste in an optimal form, thus contributing to the solution of one of the major remaining problems for deployment of nuclear power. 19 refs

The EL-4 reactor. Changing of a pressure tube on a test loop

International Nuclear Information System (INIS)

Foulquier, H.; Clara, P.

1964-01-01

Right from the beginning of the EL-4 project, the research convected with the overall design of the reactor was guided by the various technical specifications resulting from a justifiable concern about the reliability. The external and internal tubes of each layer situated in the reactor block had in particular to be interchangeable. The research alone into the dismantling of the external tube, i.e in fact the pressure tube, justified a certain number of full-scale tests on a model. The tests carried out under relevant conditions on a non-irradiated structure made it possible to define a complete ranger of of positioning and un-positioning sequences at a distance for such a pressure tube. (authors) [fr

Optimization of reactor pressure vessel internals segmentation in Korea

Energy Technology Data Exchange (ETDEWEB)

Lee, Byung-Sik [Dankook Univ., Chungnam (Korea, Republic of). Dept. of Nuclear Engineering

2017-11-15

One of the most challenging tasks during plant decommissioning is the removal of highly radioactive internal components from the reactor pressure vessel (RPV). For RPV internals dismantling, it is essential that all activities are thoroughly planned and discussed in the early stage of the decommissioning project. One of the key activities in the detailed planning is to prepare the segmentation and packaging plan that describes the sequential steps required to segment, separate, and package each individual component of RPV, based on an activation analysis and component characterization study.

Feedback from dismantling operations (level 2) on EDF's first generation reactors

International Nuclear Information System (INIS)

West, J P.; Dionisio-Gomes, A.; Kus, J P.; Mervaux, P.; Bernet, P.; Dalmas, R.

2003-01-01

EDF's policy as regards the dismantling of the reactors that have ceased commercial operation, namely the eight power plants of the first generation and the Creys-Malville power plant, is explained. Generally speaking, prior to the year 2001, EDF had opted for the de-construction of these power plants to comply with a 'long wait' scenario, which consisted of waiting for a period of 5 to 10 years to achieve IAEA level 2 (partial release of the site), then postponing the total de-construction of the facilities for 25 to 50 years. Today, EDF has decided to undertake the total de-construction of these reactors, which have ceased commercial operation, over a period of 25 years. The purpose of this document is to present: - The reactors concerned, their background and their 'regulatory' situation, - The main operations performed and/or currently in progress, - The main elements of feedback from such operations, shedding light on the approach adopted in 2001. The installations concerned by the de-construction programme are as follows: - The 8 power plants of the first generation, which were built during the fifties and sixties and ceased commercial operation between 1973 and 1994, namely: Brennilis (industrial prototype using heavy water technology, jointly operated by EDF and CEA), the 6 power units of the NUGG type (natural uranium gas graphite) at Chinon, Saint-Laurent des Eaux and Bugey and the PWR reactor at Chooz A, - The storage silos at Saint-Laurent, where the sleeves for the fuel assemblies of reactors SLA1 and SLA2 are stored, corresponding to approximately 2000 tonnes of graphite, - The Creys-Malville reactor, FBR (fast breeder reactor) shut down in accordance with a government decision, which is currently undergoing decommissioning. At the current stage, our feedback from the dismantling operations carried out on nuclear facilities is based on (i) the work carried out or in progress that will make it possible to achieve the equivalent of IAEA level 2 in the

State of dismantling of reactor facilities (JPDR) in Tokai Research Establishment, Japan Atomic Energy Research Institute (fiscal year 1986)

International Nuclear Information System (INIS)

1987-01-01

As to this dismantling work, the contents of the notice on the dismantling and the policy of administration offices to deal with it were reported to the Nuclear Safety Commission beforehand, and after the approval was obtained, it has been executed. Based on the talk of the chairman of Nuclear Safety Commission on January 6, 1983, the state of dismantling is reported. In fiscal year 1986, the second stage dismantling was begun in December, and it was confirmed that the works were carried out safety. In order to ensure the place required for dismantling and removing in-core structures and the pressure vessel, the pressure vessel upper cover and its heat insulator were removed from the third story of the containment vessel. A part of the facilities installed on the second and third stories of the containment vessel was also dismantled and removed. In order to utilize as the place for the temporary preservation and decontamination of dismantled things, a part of the facilities installed in the dump condenser building was dismantled and removed. The control building was reconstructed for smoothly carrying out the entrance control of workers. 36 spent fuel assemblies were carried away for reprocessing. The exposure dose of workers was below the detectable limit of film badges. The dismantled wastes were about 171 t of metals and 34 t of concrete. (Kako, I.)

Dismantling of nuclear facilities and related problems - Conference proceedings

International Nuclear Information System (INIS)

Tournebize, Frederic; Bordet, Didier; Charlety, Philippe; Gore, Thierry; Estrade, Jerome; Lemaire, Hermine; Ginet, Annick; Fabrier, Lionel; Evrard, Lydie; Furois, Timothee; Butez, Marc; Dutzer, Michel; Faure, Vincent; Billarand, Yann; Menuet, Lise; Lahaye, Thierry; Pin, Alain; Mougnard, Philippe; Charavy, Sylvain; Poncet, Philippe; Moggia, Fabrice; Dochy, Arnaud; Benjamin, Patrick; Poncet, Pierre-Emmanuel; Beneteau, Yannick; Richard, Jean-Baptiste; Pellenz, Gilles; Ollivier Dehaye, Catherine; Gerard, Stephane; Denissen, Luc; Davain, Henri; Duveau, Florent; Guyot, Jean-Luc; Ardellier, Luc

2012-11-01

The oldest French nuclear facilities, built for some of them in the 1950's for research or power generation purposes, have reached more or less the end of their life. More than 30 facilities have entered the shutdown or dismantling phase, among which 8 reactors of the very first generations of Electricite de France (EdF) reactors. The aim of this two-days conference is to take stock of the present day status and perspectives of the dismantling activity, to approach the question of the management of the wastes produced, and to share experience about large scale operations already carried out. This document gathers the available presentations given during this conference: 1 - the 'Passage' project (F. Tournebize); 2 - CEA-Grenoble: from Louis Neel to key enabling technologies (D. Bordet); 3 - Dismantling actions in France (L. Evrard); 4 - Securing control of long-term charges funding (T. Furois); 5 - Waste disposal projects and their contribution to the management of dismantling wastes (M. Butez); 6 - Specificities linked with dismantling activities (Y. Billarand); 7 - Dismantling safety: the ASN's point of view (L. Evrad); 8 - Labor Ministry viewpoint about the dismantling related questions (T. Lahaye); 9 - Consideration of organizational and human factors in dismantling operations: a new deal in the operators-service providers relation (L. Menuet); 10 - Diploma and training experience (A. Pin); 11 - Glove-boxes dismantling at La Hague plant - status and experience feedback (P. Mougnard); 12 - Dismantling of Siloe reactor (CEA-Grenoble): application of the ALARA approach (P. Charlety); 13 - BR3 - a complex dismantling: the neutron shield tank (NST) in remote operation and indirect vision (L. Denissen); 14 - Cleansing and dismantling of the Phebus PF containment (S. Charavy); 15 - Integration of dismantling at the design and exploitation stages of nuclear facilities (P. Poncet); 16 - Consideration during the design and exploitation stages of dispositions aiming at

Activation calculations for dismantling - The feedback of a 7 years experience in activation calculations for graphite gas cooled reactors in France

International Nuclear Information System (INIS)

Eid, M.; Nimal, J.C.; Gerat, L.M.

1994-01-01

This is a revision of the past seven years experience in activation calculations for dismantling. It aims at evaluating the experience and at making better understanding to help in decision making during the following phases. Five gas cooled reactors are shutdown and are waiting for the EDF (Electricite De France) dismantling decision. The sixth (BUGEY1) will be shutdown by 1994 and will be waiting a dismantling decision as well. (authors). 3 figs., 3 tabs

Tools and tool application for the dismantling of the nuclear power plant Brennilis in France

International Nuclear Information System (INIS)

Bienia, Harald; Welbers, Philipp; Krueger, Peter; Noll, Thomas

2012-01-01

The EL-4 reactor in the NPP Brennilis in France is a CO2 cooled heavy water moderated test reactor with net power of 70 MW, the reactor started operation in 1967 and was decommissioned in 1985. Due to the construction features it was not necessary to enter the reactor area during operation, therefore the reactor pressure vessel and the surrounding piping systems are built in a very compact way. The dismantling procedures are therefore different from German BWR or PWR systems, the remote cutting and handling tools have to be adapted to the different features. Because of the high local dosage rate in the reactor hall it is also necessary to perform the erection of the dismantling equipment by robot systems. For cutting of the piping system a new plasma cutting technique, the hot wire method will be used. Other mechanical cutting techniques have to be used for instance for zircaloy containing components due to fire prevention purposes. The required time for tool and manipulator changes, including wearing part replacements constitute a significant part of the dismantling schedule. The suction/exhaust system for radioactive dust removal allowed a reduction of the total personal dose by one third of the allowed dose.

Method for dismantling shields

International Nuclear Information System (INIS)

Fukuzawa, Rokuro; Kondo, Nobuhiro; Kamiyama, Yoshinori; Kawasato, Ken; Hiraga, Tomoaki.

1990-01-01

The object of the present invention is to enable operators to dismantle shieldings contaminated by radioactivity easily and in a short period of time without danger of radiation exposure. A plurality of introduction pipes are embedded previously to the shielding walls of shielding members which contain a reactor core in a state where both ends of the introduction pipes are in communication with the outside. A wire saw is inserted into the introduction pipes to cut the shieldings upon dismantling. Then, shieldings can be dismantled easily in a short period of time with no radiation exposure to operator's. Further, according to the present invention, since the wire saw can be set easily and a large area can be cut at once, operation efficiency is improved. Further, since remote control is possible, cutting can be conducted in water and complicated places of the reactor. Biting upon starting the wire saw in the introduction pipe is reduced to facilitate startup for the rotation. (I.S.)

Dismantling system of concrete thermal shielding walls

International Nuclear Information System (INIS)

Machida, Nobuhiro; Saiki, Yoshikuni; Ono, Yorimasa; Tokioka, Masatake; Ogino, Nobuyuki.

1985-01-01

Purpose: To enable safety and efficient dismantling of concrete thermal shielding walls in nuclear reactors. Method: Concrete thermal shielding walls are cut and dismantled into dismantled blocks by a plasma cutting tool while sealing the top opening of bioshielding structures. The dismantled blocks are gripped and conveyed. The cutting tool is remote-handled while monitoring on a television receiver. Slugs and dusts produced by cutting are removed to recover. Since the dismantling work is carried out while sealing the working circumstance and by the remote control of the cutting tool, the operators' safety can be secured. Further, since the thermal sealing walls are cut and dismantled into blocks, dismantling work can be done efficiently. (Moriyama, K.)

Nuclear installations: decommissioning and dismantling

International Nuclear Information System (INIS)

Anon.

1995-01-01

This document is a compilation of seven talks given during the 1995 EUROFORUM conference about decommissioning and dismantling of Nuclear installations in the European Community. The first two papers give a detailed description of the legal, financial and regulatory framework of decommissioning and dismantling of nuclear facilities in the European Union and a review of the currently available decommissioning techniques for inventory, disassembly, decontamination, remote operations and management of wastes. Other papers describe some legal and technical aspects of reactor and plants dismantling in UK, Germany, Spain and France. (J.S.)

Decommissioning experience of the Japan power demonstration reactor

International Nuclear Information System (INIS)

Hoshi, T.; Yanagihara, S.; Tachibana, M.; Momma, T.

1992-01-01

Actual dismantling of the Japan Power Demonstration Reactor (JPDR) has been progressing since 1986 aiming to make stage 3 condition as the final goal. Such highly activated components as the reactor pressure vessel (RPV) and the inner portion of biological shield concrete close to the RPV have removed using the remotely operated cutting machines. Useful data on the dismantling techniques and their safety as well as the manpower expenditure and radiation exposure of workers have been obtained. Experiences gained through the dismantling works are described in this paper. (author)

Clean-up and dismantling, Dismantling - legacy of the past, prospects for the future: CEA, a pioneer in the dismantling process, nuclear dismantling, research and innovation dedicated to dismantling

International Nuclear Information System (INIS)

Lorec, Amelie

2016-01-01

France - a world leader in the whole nuclear power cycle - is also responsible for the clean-up and dismantling of its end-of-life nuclear facilities. Here, the CEA is considered to be a pioneer both in the project ownership of work sites and in the R and D for optimising the timescales, costs and safety of those work sites. Its responsibilities range from defining the most appropriate scenario, characterising the radiological state of equipment and decontaminating premises, carrying out dismantling and optimising the resulting waste. With this wide range of skills and the diversity of its facilities, the CEA Nuclear Energy Division is developing innovative solutions which are already the subject of industrial transfers. Two-thirds of France's end-of-life nuclear facilities belong to the CEA - a situation connected with its history. This implies setting up clean-up and dismantling work sites which have unprecedented scientific, human and financial challenges. Every regulated nuclear installation (INB) (nuclear reactors, laboratories, etc.) has a limited operating life. When it stops being used, it is first cleaned up (removal of radioactive substances), then dismantled (disassembly of components) in accordance with the baseline safety requirements, and finally decommissioned so that it can be used for other purposes or be demolished. Cleanup and dismantling operations concern all the facility's components, such as hot (shielded) cells which can be found in some laboratories. As the owner of its clean-up and dismantling projects, the CEA also devotes a significant amount of R and D to reducing the timescales, costs and waste from current and future programmes, while improving their safety. The resulting innovations often lead to industrial transfers. (authors)

Dismantling at the CEA's Nuclear Energy Division: strategy and programmes

International Nuclear Information System (INIS)

Lecomte, C.; Prunele, D. de; Rozain, J.P.; Nokhamzon, J.G.; Tallec, M.

2008-01-01

The CEA's Nuclear Energy Division (DEN) nuclear facilities currently include seventeen reactors and thirty six other miscellaneous facilities, particularly laboratories, fuel processing units and facilities specific to waste management. Some of these are currently being dismantled or must be dismantled soon so that the DEN, the Nuclear Energy Division, can construct new equipment and thus have available a range of R and D facilities in line with the issues of the nuclear industry of the future. At CEA, the first nuclear facility dismantling operations go back several dozen years and involve numerous and varied facilities. The first operations of any significance took place in the 1960's and 1970's and covered, for example, the first plutonium plant at Fontenay-aux-Roses (total dismantling) and small research reactors or critical models - CESAR and PEGGY at Cadarache and MINERVE at Fontenay-aux Roses (civil engineering cleaned up and kept). At La Hague, the dismantling of AT1, a pilot workshop used by the CEA during the 1970's to process irradiated fuels from fast neutron reactors, was completed in March 2001 (IAEA former stage 3, excluding civil engineering demolition). On the other hand, during this period of first dismantling, the intermediate-sized reactors (G1, Rapsodie) were only partially dismantled after shut down, mainly due to the lack of graphite and sodium waste management routes at the time. About twenty facilities were thus dealt with up to 2001, in other words about half of all the nuclear facilities shut down permanently before this date. (authors)

Study on treatment of dust by dismantling

International Nuclear Information System (INIS)

Torikai, K.; Suzuki, K.

1987-01-01

In dismantling of nuclear reactors, various kinds of treatment of dust generated by cutting or dismantling concrete structures of components of reactors are evaluated for safety, cost, and performance comparing the work in air with water. A method of dust treatment for work in air is discussed. The dry method has an easy operation in practice and a good performance in the equipment, but has problem on the prevention from radioactive contamination by diffusion of dust in air. For the purpose of advancing the strong points and eliminating the weak points in dry method, an improved venturi scrubber system is proposed for dismantling work as a dust collecting system. The system consists of dust absorbing pipe, dust collector, separator of dust and water and dust transfer equipment to a storage of waste. This system would be expected to have better performance and lower operating cost in decommissioning nuclear reactors, especially, the number of dust filters, for example, HEPA filters, will be considerably saved

The promising opportunity of dismantlement

International Nuclear Information System (INIS)

Anon.

2009-01-01

Civil engineering, mechanics and waste conditioning companies are thriving around the market of nuclear facilities dismantlement which is promised to a huge development in the coming decade. This paper presents a map of the opportunities of the dismantlement market throughout Europe (research and power reactors, fuel fabrication plants, spent fuel reprocessing plants) and a cost estimation of a given dismantling work with respect to the different steps of the work. In France a small core of about twenty companies is involved in nuclear dismantlement but the French market is also looking towards foreign specialists of this activity. The British market is also targeted by the French companies but for all the actors the technological or commercial advance gained today will be determining for the future markets. (J.S.)

Overall strategy of Creys Malville power station dismantling

International Nuclear Information System (INIS)

Alphonse, P.

2002-01-01

The power station was stopped by a government decision following the elections in 1997. This shutdown was then made official by a letter dated April 1998 and the decree of December 1998. This was a non-technical shutdown and as such had not been envisaged; there has been no early warning. Current dismantling strategy: The studies leading to shutdown and then dismantling were engaged in 1998 based on a scenario with a status corresponding to IAEA level 2 until 2046. In 2001, EDF management made the decision to dismantle all the first generation power stations and Creys Malville between now and 2025. It should be noted that the presence of strongly irradiated stellite in the Creys Malville reactor would still require remote systems for working in the reactor block after 2046. The sequence of operations dictated by the dismantling strategy is as follows: eliminate the risks as soon as possible and in particular the risk related to the sodium, 3300 tonnes of which is kept in liquid form in the reactor vessel; dismantle the most active parts which are too radioactive to be sent to the existing or planned storage centres. This may lead to on-site storage to allow decay to occur before sending to a storage centre; planning of the work interventions in order to limit the costs

Hot cell examination on the surveillance capsule of SA 533 cl. 1 reactor pressure vessel (1st test report)

Energy Technology Data Exchange (ETDEWEB)

Choo, Yong Sun; Jung, Y. H.; Yoo, B. O.; Baik, S. J.; Oh, W. H.; Soong, W. S.; Hong, K. P

2000-08-01

The post-irradiated examinations such as impact test, tensile test, composition analysis and etc. were conducted to monitor and to evaluate the radiation-induced changes, so called radiation embrittlement, in the mechanical properties of ferritic materials. Those data should be applied to confirm safety as well as reliability of reactor pressure vessel. The scopes and contents of hot cell examination on the surveillance capsule are as follows; - Capsule transportation, cutting, dismantling and classification - Shim block and Dosimeter cutting and dismantling - Impact test - Tensile test - Composition analysis by EPMA - SEM observation on the fractured surface - Hardness test - Radwaste treatment.

Decontamination before dismantling a fast breeder reactor primary cooling system

International Nuclear Information System (INIS)

Costes, J.R.; Antoine, P.; Gauchon, J.P.

1997-01-01

The large-scale decontamination of FBR sodium loops is a novel task, as only a limited number of laboratory-scale results are available to date. The principal objective of this work is to develop a suitable decontamination procedure for application to the primary loops of the RAPSODIE fast breeder reactor as part of decommissioning to Stage 2. After disconnecting the piping from the main vessel, the pipes were treated by circulating chemical solutions and the vessels by spraying. The dose rate in the areas to be dismantled was divided by ten. A decontamination factor of about 300 was obtained, and should allow austenitic steel parts to be melted in special furnaces for unrestricted release. (author)

Aspects of reactor dismantling planning following the safe entombment in the NPP Lingen (KWL); Aspekte der Abbauplanung nach dem Sicheren Einschluss im Kernkraftwerk Lingen (KWL)

Energy Technology Data Exchange (ETDEWEB)

Priesmeyer, U.; Rojahn, T.; Fries, B. [Kernkraftwerk Lingen GmbH (Germany)

2009-07-01

The NPP Lingen (KWL) was shut-down in 1977. Due to the fact that no final repository was available the safe entombment for 25 years was chosen following the decommissioning. The conventional plant components were dismantled and removed from the plant site. The licensing procedure for reactor dismantling with final disposal in Schacht Konrad has been started. The beginning of dismantling operation is scheduled for 2013. The authors describe the preparatory work, the boundary conditions for the dismantling, radiation protection considerations with respect to manual demolition work after the rather long decay time.

Melting of contaminated steel scrap from the dismantling of the CO2 systems of gas cooled, graphite moderated nuclear reactors

International Nuclear Information System (INIS)

Feaugas, J.; Jeanjacques, M.; Peulve, J.

1994-01-01

G2 and G3 are the natural Uranium cooled reactors Graphite/Gas. The two reactors were designed for both plutonium and electricity production (45 MWe). The dismantling of the reactors at stage 2 has produced more than 4 000 tonnes of contaminated scrap. Because of their large mass and low residual contamination level, the French Atomic Energy Commission (CEA) considered various possibilities for the processing of these metallic products in order to reduce the volume of waste going to be stored. After different studies and tests of several processes and the evaluation of their results, the choice to melt the dismantled pipeworks was taken. It was decided to build the Nuclear Steel Melting Facility known as INFANTE, in cooperation with a steelmaker (AHL). The realization time schedule for the INFANTE lasted 20 months. It included studies, construction and the licensing procedure. (authors). 2 tabs., 3 figs

Abrasive water jet cutting technique for biological shield concrete dismantlement

International Nuclear Information System (INIS)

Konno, T.; Narazaki, T.; Yokota, M.; Yoshida, H.; Miura, M.; Miyazaki, Y.

1987-01-01

The Japan Atomic Energy Research Institute (JAERI) is developing the abrasive-water jet cutting system to be applied to dismantling the biological shield walls of the JPDR as a part of the reactor dismantling technology development project. This is a total system for dismantling highly activated concrete. The concrete biological shield wall is cut into blocks by driving the abrasive-water jet nozzle, which is operated with a remote, automated control system. In this system, the concrete blocks are removed to a container, while the slurry and dust/mist which are generated during cutting are collected and treated, both automatically. It is a very practical method and will quite probably by used for actual dismantling of commercial power reactors in the future because it can minimize workers' exposure to radioactivity during dismantling, contributes to preventing diffusion of radiation, and reduces the volume of contaminated secondary waste

Adaptation of high pressure water jets with abrasives for nuclear installations dismantling

International Nuclear Information System (INIS)

Rouviere, R.; Pinault, M.; Gasc, B.; Guiadeur, R.; Pilot, M.

1989-01-01

This report presents the work realized for adjust the cutting technology with high pressure water jet with abrasives for nuclear installation dismantling. It has necessited the conception and the adjustement of a remote tool and the realization of cutting tests with waste produce analysis. This technic can be ameliorated with better viewing systems and better fog suction systems

CP-5 reactor remote dismantlement activities: Lessons learned in the integration of new technology in an operations environment

International Nuclear Information System (INIS)

Noakes, M.W.

1998-01-01

This paper presents the developer's perspective on lessons learned from one example of the integration of new prototype technology into a traditional operations environment. The dual arm work module was developed by the Robotics Technology Development Program as a research and development activity to examine manipulator controller modes and deployment options. It was later reconfigured for the dismantlement of the Argonne National Laboratory Chicago Pile No. 5 reactor vessel as the crane-deployed dual arm work platform. Development staff worked along side operations staff during a significant part of the deployment to provide training, maintenance, and tooling support. Operations staff completed all actual remote dismantlement tasks. At the end of available development support funding, the Dual Arm Work Platform was turned over to the operations staff, who are still using it to complete their dismantlement tasks

Decommissioning of a small reactor (BR3 reactor, Belgium)

International Nuclear Information System (INIS)

Dadoumont, J.; Massaut, V.; Klein, M.; Demeulemeester, Y.

2002-01-01

Since 1989, SCK-CEN has been dismantling its PWR reactor BR3 (Belgian Reactor No. 3). After gaining a great deal of experience in remote dismantling of highly radioactive components during the actual dismantling of the two sets of internals, the BR3 team completed the cutting of its reactor pressure vessel (RPV). During the feasibility phase of the RPV dismantling, a decision was made to cut it under water in the refuelling pool of the plant, after having removed it from its cavity. The RPV was cut into segments using a milling cutter and a bandsaw machine. These mechanical techniques have shown their ability for this kind of operations. Prior to the segmentation, the thermal insulation situated around the RPV was remotely removed and disposed of. The paper will describe all these operations. The BR3 decommissioning activities also include the dismantling of contaminated loops and equipment. After a careful sorting of the pieces, optimized management routes are selected in order to minimize the final amount of radioactive waste to be disposed of. Some development of different methods of decontamination were carried out: abrasive blasting (or sand blasting), chemical decontamination (Oxidizing-Reducing process using Cerium). The main goal of the decontamination program is to recycle most of the metallic materials either in the nuclear world or in the industrial world by reaching the respective recycling or clearance level. Overall the decommissioning of the BR3 reactor has shown the feasibility of performing such a project in a safe and economical way. Moreover, BR3 has developed methodologies and decontamination processes to economically reduce the amount of radwaste produced. (author)

SGN's Dismantling and Decommissioning engineering, projects experience and capabilities

International Nuclear Information System (INIS)

Destrait, L.

1998-01-01

Its experience in waste treatment, conditioning, storage and disposal, its cooperation with CEA and COGEMA Group in license agreements give SGN expertise in the decommissioning field. SGN's experience and background in all areas of nuclear facility decommissioning, such as chemical and mechanical cells, nuclear advanced reactors, reprocessing facilities result in fruitful references to the customers. The poster is presenting different achievements and projects with SGN's participation such as: - The decommissioning of Windscale Advanced Gas cooled Reactors (WAGR), in particular providing methodology and equipment to dismantle the Pressure and Insulation Vessel of the reactor. - The decommissioning plan of Ignalina (Lithuania) and Paldiski (Estonia), defining strategies, scenarios, necessary equipments and tools and choosing the best solutions to decommission the site under different influencing parameters such as cost, dose rate exposure, etc... - Th One Site Assistance Team (OSAT) at Chernobyl regarding the preparation works for the waste management and decommissioning of the plant. - The decommissioning of French nuclear facilities such as reprocessing (UP1) and reactor (EL4) plants. The important experience acquired during the facility management and during the first dismantling and decommissioning operations is an important factor for the smooth running of these techniques for the future. The challenge to come is to control all the operations, the choice of strategies, the waste management, the efficiency of tools and equipments, and to provide nuclear operators with a full range of proven techniques to optimise costs and minimize decommissioning personnel exposure. (Author)

Achievements and prospects of robotics in dismantling operations

International Nuclear Information System (INIS)

Clement, G.; Goetghebeur, S.; Ravera, J.P.

1993-01-01

After a definition of 'robotic systems' (poly functionality is the main concept), the nuclear facilities that have used robotic systems for their dismantling are reviewed; the various robot intervention domains in dismantling, the different types of machines and the work carried out by robots are presented. Difficulties arising from robot utilization for reactor dismantling, robot design considerations, reliability, personnel training needs, tooling and costs are discussed. Applicability criteria are derived concerning radio protection, hard working conditions, task complexity, multiplicity and quality, and costs

Status of the Digital Mock-up System for the dismantling of the nuclear facilities

International Nuclear Information System (INIS)

Park, Hee Seoung; Kim, S. K.; Lee, K. W.; Oh, W. J.

2004-12-01

The database system have already developed is impossible to solve a quantitative evaluation about a various situation from the dismantle activities of the reactor had contaminated with radioactivity. To satisfy the requirements for safety and economical efficiency among a major decommissioning technologies, it need a system that can evaluate and estimate dismantling scheduling, amount of radioactive waste being dismantled, and decommissioning cost. We have review and analyzed status of the digital mock-up system to get a technical guide because we have no experience establishment of one relation to dismantling of research reactor and nuclear power plant

Sampling of reactor pressure vessel and core internals

International Nuclear Information System (INIS)

Oberhaeuser, Ralf

2012-01-01

Decommissioning and dismantling of nuclear power plants is a growing business as a huge number of plants built in the 1970's have now reached their lifetime. It is well known that dismantling a nuclear power plant means an extraordinary expense for the owner respectively operator. Beside the dismantling works for itself, the disposal of activated components and other nuclear waste is very expensive. What comes next is the fact that final disposal facilities are not available yet in most countries meaning a need for interim storage on-site in specially built facilities. It can be concluded that a special attention is paid on producing a minimal radioactive waste volume. For this, optimized dismantling and packaging concepts have to be developed. AREVA is proud of versatile experience in successfully dismantling nuclear components like core internals and reactor pressure vessel (RPV). The basis of a well-founded and optimized dismantling and packaging concept must always be the detailed knowledge of the radiological condition of the component to be and in the best case a 3D activation- model. For keeping the necessary sampling effort as small as possible, but simultaneously as efficient as possible, representative sampling positions are defined in advance by theoretical radiological examinations. For this, a detailed 3D-CAD-model of the components to be dismantled has proven very helpful and effective. Under these aspects a sampling of RPV and its components is necessary to verify the theoretically calculated radiological data. The obtained results of activation and contamination are taken into account for the optimized dismantling and packaging strategy. The precise 3D-activation-model will reduce the necessary number and type of final disposal containers as security factors are minimized leading to a lower shielding effort, too. Besides, components or even parts of components may be subject of release measurement. In the end, costs can be reduced. In this context

Decontamination and dismantlement of the JANUS Reactor at Argonne National Laboratory-East. Project final report

International Nuclear Information System (INIS)

Fellhauer, C.R.; Clark, F.R.

1997-10-01

The decontamination and dismantlement of the JANUS Reactor at Argonne National Laboratory-East (ANL-E) was completed in October 1997. Descriptions and evaluations of the activities performed and analyses of the results obtained during the JANUS D and D Project are provided in this Final Report. The following information is included: objective of the JANUS D and D Project; history of the JANUS Reactor facility; description of the ANL-E site and the JANUS Reactor facility; overview of the D and D activities performed; description of the project planning and engineering; description of the D and D operations; summary of the final status of the JANUS Reactor facility based upon the final survey results; description of the health and safety aspects of the project, including personnel exposure and OSHA reporting; summary of the waste minimization techniques utilized and total waste generated by the project; and summary of the final cost and schedule for the JANUS D and D Project

Development of project management data calculation models relating to dismantling of nuclear facilities. Contract research

Energy Technology Data Exchange (ETDEWEB)

Sukegawa, Takenori; Ohshima, Soichiro; Shiraishi, Kunio; Yanagihara, Satoshi [Department of Decommissioning and Waste Management, Tokai Research Establishment, Japan Atomic Energy Research Institute, Tokai Ibaraki (Japan)

1999-02-01

Labor-hours necessary for dismantling activities are generally estimated based on experience, for example, as a form of unit productivity factors such as the relationship between labor-hours and weight of components dismantled which were obtained by actual dismantling activities. The project management data calculation models together with unit productivity factors for basic dismantling work activities were developed by analyzing the data obtained from the Japan Power Demonstration Reactor (JPDR) dismantling project, which will be applicable to estimation of labor-hours in various dismantling conditions. Typical work breakdown structures were also prepared by categorizing repeatable basic dismantling work activities for effective planning of dismantling activities. The labor-hours for dismantling the JPDR components and structures were calculated by using the code system for management of reactor decommissioning (COSMARD), in which the work breakdown structures and the calculation models were contained. It was confirmed that the labor-hours could be easily estimated by COSMARD through the calculations. This report describes the labor-hour calculation models and application of these models to COSMARD. (author)

A structural evaluation of the Shippingport reactor pressure vessel for transport impact conditions

International Nuclear Information System (INIS)

Witte, M.C.; Chou, C.K.

1989-01-01

The Shippingport Atomic Power Station in Shippingport, Pennsylvania, is being decommissioned and dismantled. This government-leased property will be returned, in a radiologically safe condition, to its owner. All radioactive material is being removed from the Shippingport Station and transported for burial to the DOE Hanford Reservation in Richland, Washington. The reactor pressure vessel (RPV) will be transported by barge to Hanford. This paper describes an evaluation of the structural response of the RPV to the normal and accident impact test conditions as required by the Code of Federal Regulations. 3 refs., 5 figs., 3 tabs

Remote control for the underwater dismantling of reactor internals at the nuclear power plant Gundremmingen unit A

International Nuclear Information System (INIS)

Eickelpasch, N.; Steiner, H.; Priesmeyer, U.

1996-01-01

The unit A of the nuclear power plant in Gundremmingen (KRB A) is a boiling water reactor with an electrical power of 250 MW e . It was shut down in 1977 after 11 years of operation. The actual decommissioning started in 1983. Meanwhile more than 5200 tons of contaminated components have been dismantled. Special cutting and handling tools were tested, developed and optimized for the purpose of working in radiation fields and under water. Due to the special design of KRB A, using an dual cycle system for additional steam generation, the experience gained is transferable to pressurised water reactors as well. (Author)

Clearance of radioactive materials during reactor dismantling. Permanent enclosure instead of demolition and renaturation?; Freigabe radioaktiven Materials beim AKW-Abriss. Dauerhafter Einschluss statt Rueckbau?

Energy Technology Data Exchange (ETDEWEB)

NONE

2016-07-01

During reactor dismantling besides high-level radioactive wastes a large amount of low-level contaminated steel and concrete has to be disposed. In case that radioactivity falls below defined dose limits (10 micro Sv/person and year) these materials may be disposed in domestic waste landfill or in municipal incineration facilities. The issue is discussed in detail including the fact that many power plants are dismantled at the same time so that the contaminated materials might accumulate. Another issue is the occupational safety of contract workers during dismantling. The permanent enclosure could avoid this environmental contamination of decommissioned power plants might also be less expensive.

Technology and costs for dismantling a Swedish nuclear power plant

International Nuclear Information System (INIS)

1979-10-01

Various estimates concerning the costs of decommissioning a redundant nuclear power reactor to the green fields state are given in the literature. The purpose of this study is to provide background material for the Swedish nuclear power utilities to estimate the costs and time required to dismantle an ASEA-ATOM Boiling Water Reactor. The units Oskarshamn II and Barsebeck 1, both with an installed capacity of approximately 600 MW, serve as reference plants. The time of operation before final shutdown is assumed to be 40 years. Dismantling operations are initiated one year after shutdown. When the dismantling of the plant is finished, the site is to be released for unrestricted use. The costs for dismantling and subsequent final disposal of the radioactive waste are estimated at approximately SEK 500 million (approximately US dollars 120 million) in terms of 1979 prices. The sum includes 25% contingency. The dismantling cost is equivalent to 10-15% of the installation cost of an equivalent new nuclear power plant. The exact percentage is dependent on the interest rate during the construction period. It is shown in the study that a total dismantling can be accomplished in less than five years. This report is a compilation of studies performed by ASEA-ATOM and VBB based on premises given by KBS. The reports from these studies are presented in appendices. (Auth.)

The management routes for materials produced by the dismantling of the BR3-PWR reactor

International Nuclear Information System (INIS)

Klein, M.; Demeulemeester, Y.; Ponnet, M.; Emond, M.; Emond, O.; Dadoumont, J.; Massaut, V.

2000-01-01

The dismantling of the BR3 reactor produces quite large masses of contaminated materials, mainly metals or concrete. The main management routes are: conditioning of the radioactive wastes and disposal, recycling of radioactive materials in the nuclear sector and the recycling of free released materials in the industrial sector or their evacuation as industrial waste. The conditioning of the radioactive wastes is essentially performed in the installations of Belgoprocess and must follow the specifications imposed by the national radwaste management agency ONDRAF/NIRAS. The conditioning of the pieces produced during the cutting of the reactor pressure vessel is given as example. The recycling of radioactive materials in the nuclear sector is possible for metals and for concrete. For metals, SCK.CEN has an agreement with a nuclear foundry which reuses these materials for the fabrication of shieldings. For concrete, an R and D programme is going on with the objective to demonstrate the possible reuse of baryte concrete as raw materials for the production of mortar used in the conditioning of radioactive wastes. The free release of radioactive materials and their reuse or evacuation as radioactive wastes requires the strict respect of procedures and the use of low level measurement techniques. Various decontamination techniques are used at SCK.CEN to reach this objective. For the metals, we use mainly simple washing, abrasive decontamination and hard chemical decontamination. For concrete, we use mainly scabbling or shaving techniques. (authors)

Evaluating and planning the radioactive waste options for dismantling the Tokamak Fusion Test Reactor

Energy Technology Data Exchange (ETDEWEB)

Rule, K.; Scott, J.; Larson, S. [Princeton Plasma Physics Lab., NJ (United States)] [and others

1995-12-31

The Tokamak Fusion Test Reactor (TFTR) is a one-of-a kind tritium fusion research reactor, and is planned to be decommissioned within the next several years. This is the largest fusion reactor in the world and as a result of deuterium-tritum reactions is tritium contaminated and activated from 14 Mev neutrons. This presents many unusual challenges when dismantling, packaging and disposing its components and ancillary systems. Special containers are being designed to accommodate the vacuum vessel, neutral beams, and tritium delivery and processing systems. A team of experienced professionals performed a detailed field study to evaluate the requirements and appropriate methods for packaging the radioactive materials. This team focused on several current and innovative methods for waste minimization that provides the oppurtunmost cost effective manner to package and dispose of the waste. This study also produces a functional time-phased schedule which conjoins the waste volume, weight, costs and container requirements with the detailed project activity schedule for the entire project scope. This study and project will be the first demonstration of the decommissioning of a tritium fusion test reactor. The radioactive waste disposal aspects of this project are instrumental in demonstrating the viability of a fusion power reactor with regard to its environmental impact and ultimate success.

Robotics take heat out of reactor. [Windscale AGR decommissioning

Energy Technology Data Exchange (ETDEWEB)

Rufford, N

1986-12-04

The Windscale prototype reactor is being decommissioned and dismantled. The stages are outlined. The first phase began in 1985 and included construction of a waste packaging plant annexed to the steel dome. The boilers will be cut up and, once decontaminated, probably sold for scrap. The second phase involves dismantling the reactor itself. Much of this will be done by a semi-automatic robot which is being specially built and tested. The robot will have an extendable arm with a manipulator which will be equipped with bolt croppers, shears, a saw and oxypropane cutter. This robot will cut up the pressure vessel in sections ready for encasing in concrete. Lessons learnt from the dismantling will be used in future reactor designs and specifications (eg the need to use steels with fewer impurities, especially cobalt). Ultimate disposal of the concrete waste blocks is undecided. (U.K.).

Optimization study and preliminary design for Latina NPP early core retrieval and reactor dismantling

International Nuclear Information System (INIS)

Macci, E.; Zirpolo, S.; Imparato, A.; Cacace, A.; Parry, D.; Walkden, P.

2002-01-01

In June 2000, an agreement was established between Sogin and BNFL to enable the two companies to co-operate, using their specific experiences in the decommissioning field, for the benefit of projects in Italy, the United Kingdom and for third markets. A decommissioning strategy for the Latina NPP was initially developed in a Phase 1 Study which produced a conceptual design for the decommissioning of the reactor. This study was completed in June 2000. Since then, a second study has been completed, which has further developed the strategy and produced preliminary designs for the early dismantling of the core and reactor building at Latina. The engineering and safety data were produced in order to support Sogin in the preparation of a safety case for plant decommissioning. This safety case was submitted to the Italian Regulator, ANPA, in February 2002. (author)

Pressure tube reactor

International Nuclear Information System (INIS)

Seki, Osamu; Kumasaka, Katsuyuki.

1988-01-01

Purpose: To remove the heat of reactor core using a great amount of moderators at the periphery of the reactor core as coolants. Constitution: Heat of a reactor core is removed by disposing a spontaneous recycling cooling device for cooling moderators in a moderator tank, without using additional power driven equipments. That is, a spontaneous recycling cooling device for cooling the moderators in the moderator tank is disposed. Further, the gap between the inner wall of a pressure tube guide pipe disposed through the vertical direction of a moderator tank and the outer wall of a pressure tube inserted through the guide pipe is made smaller than the rupture distortion caused by the thermal expansion upon overheating of the pressure tube and greater than the minimum gap required for heat shiels between the pressure tube and the pressure tube guide pipe during usual operation. In this way, even if such an accident as can not using a coolant cooling device comprising power driven equipment should occur in the pressure tube type reactor, the rise in the temperature of the reactor core can be retarded to obtain a margin with time. (Kamimura, M.)

Dismantlement and Radioactive Waste Management of DPRK Nuclear Facilities

Energy Technology Data Exchange (ETDEWEB)

Jooho, W.; Baldwin, G. T.

2005-04-01

One critical aspect of any denuclearization of the Democratic People’s Republic of Korea (DPRK) involves dismantlement of its nuclear facilities and management of their associated radioactive wastes. The decommissioning problem for its two principal operational plutonium facilities at Yongbyun, the 5MWe nuclear reactor and the Radiochemical Laboratory reprocessing facility, alone present a formidable challenge. Dismantling those facilities will create radioactive waste in addition to existing inventories of spent fuel and reprocessing wastes. Negotiations with the DPRK, such as the Six Party Talks, need to appreciate the enormous scale of the radioactive waste management problem resulting from dismantlement. The two operating plutonium facilities, along with their legacy wastes, will result in anywhere from 50 to 100 metric tons of uranium spent fuel, as much as 500,000 liters of liquid high-level waste, as well as miscellaneous high-level waste sources from the Radiochemical Laboratory. A substantial quantity of intermediate-level waste will result from disposing 600 metric tons of graphite from the reactor, an undetermined quantity of chemical decladding liquid waste from reprocessing, and hundreds of tons of contaminated concrete and metal from facility dismantlement. Various facilities for dismantlement, decontamination, waste treatment and packaging, and storage will be needed. The shipment of spent fuel and liquid high level waste out of the DPRK is also likely to be required. Nuclear facility dismantlement and radioactive waste management in the DPRK are all the more difficult because of nuclear nonproliferation constraints, including the call by the United States for “complete, verifiable and irreversible dismantlement,” or “CVID.” It is desirable to accomplish dismantlement quickly, but many aspects of the radioactive waste management cannot be achieved without careful assessment, planning and preparation, sustained commitment, and long

Dismantlement and Radioactive Waste Management of DPRK Nuclear Facilities

International Nuclear Information System (INIS)

Jooho, W.; Baldwin, G.T.

2005-01-01

One critical aspect of any denuclearization of the Democratic People's Republic of Korea (DPRK) involves dismantlement of its nuclear facilities and management of their associated radioactive wastes. The decommissioning problem for its two principal operational plutonium facilities at Yongbyun, the 5MWe nuclear reactor and the Radiochemical Laboratory reprocessing facility, alone present a formidable challenge. Dismantling those facilities will create radioactive waste in addition to existing inventories of spent fuel and reprocessing wastes. Negotiations with the DPRK, such as the Six Party Talks, need to appreciate the enormous scale of the radioactive waste management problem resulting from dismantlement. The two operating plutonium facilities, along with their legacy wastes, will result in anywhere from 50 to 100 metric tons of uranium spent fuel, as much as 500,000 liters of liquid high-level waste, as well as miscellaneous high-level waste sources from the Radiochemical Laboratory. A substantial quantity of intermediate-level waste will result from disposing 600 metric tons of graphite from the reactor, an undetermined quantity of chemical decladding liquid waste from reprocessing, and hundreds of tons of contaminated concrete and metal from facility dismantlement. Various facilities for dismantlement, decontamination, waste treatment and packaging, and storage will be needed. The shipment of spent fuel and liquid high level waste out of the DPRK is also likely to be required. Nuclear facility dismantlement and radioactive waste management in the DPRK are all the more difficult because of nuclear nonproliferation constraints, including the call by the United States for 'complete, verifiable and irreversible dismantlement,' or 'CVID.' It is desirable to accomplish dismantlement quickly, but many aspects of the radioactive waste management cannot be achieved without careful assessment, planning and preparation, sustained commitment, and long completion times

Dismantling of nuclear facilities

International Nuclear Information System (INIS)

Tallec, Michele; Kus, Jean-Pierre; Mogavero, Robert; Genelot, Gabriel

2009-01-01

Although the operational life of nuclear plants is long (around 60 years for French reactors) it is nonetheless limited in time, the stopping of it being essentially due to the obsolescence of materials and processes or to economic or safety considerations. The nuclear power plants are then subjected to cleanup and dismantling operations which have different objectives and require specific techniques. The cleanup and/or dismantling of a nuclear power produces significant quantities of waste which is generally of a different nature to that produced during the operation of the concerned plant. The radioactive waste produced by these operations is destined to be sent to the waste disposal facilities of the French National Agency for the Management of Nuclear Waste. (authors)

Dismantling of nuclear facilities: the industrial know-how; Demantelement des installations nucleaires: les voies de la maitrise industrielle

Energy Technology Data Exchange (ETDEWEB)

Lellament, R. [Societe Francaise d' Energie Nucleaire (SFEN), Groupe de Reflexion Energie/Environnement, 75 - Paris (France)

2004-11-01

Numerous nuclear facilities in laboratories or research reactors have been decommissioned and dismantled over the 2 last decades throughout the world. The valuable feedback experience has allowed nuclear industry to design, upgrade and test specific techniques for dismantling. These techniques are efficient although they have been validated on a reduced number of nuclear power plants. In France only 3 power units have been dismantled: Chinon A1, A2 and Brennilis (EL4) and they are not representative of the real park of EDF'reactors. 6 PWR-type reactors have already been dismantled in the Usa. The results of a survey concerning 26 countries shows that the dismantling cost is around 320 dollars/kWe, it represents 15% of the construction cost which is far from being excessive as it is often read in the media. The dismantling costs can be broken into: - de-construction (25-55%), - wastes from dismantling (17-43%), - security and monitoring (8-13%), - site reclamation (5-13%), and - engineering and project management (5-24%). (A.C.)

Optimized phases for reactor dismantling – an efficient and sustainable concept

International Nuclear Information System (INIS)

Krüger, S.; Winter, J.

2013-01-01

D&D projects are driven by costs, to implement an optimization process from the very beginning is key. Optimized strategy and sequencing of the dismantling (hot to cold) will provide serious economical savings . Larger dismantling packages will reduce interfaces and ease the coordination efforts on site. Early usage of mobile systems will ease the large-scale release for dismantling Social transition has to be addressed with priority and to be planned at an early phase in the D&D planning Concept, Planning & Project Management will influence the success of the project much more than the used technique

Pressure tube type reactors

International Nuclear Information System (INIS)

Komada, Masaoki.

1981-01-01

Purpose: To increase the safety of pressure tube type reactors by providing an additional ECCS system to an ordinary ECCS system and injecting heavy water in the reactor core tank into pressure tubes upon fractures of the tubes. Constitution: Upon fractures of pressure tubes, reduction of the pressure in the fractured tubes to the atmospheric pressure in confirmed and the electromagnetic valve is operated to completely isolate the pressure tubes from the fractured portion. Then, the heavy water in the reactor core tank flows into and spontaneously recycles through the pressure tubes to cool the fuels in the tube to prevent their meltdown. By additionally providing the separate ECCS system to the ordinary ECCS system, fuels can be cooled upon loss of coolant accidents to improve the safety of the reactors. (Moriyama, K.)

Long-term management of wastes resulting from dismantling operations. Storing the very low-level activity wastes at Morvilliers

International Nuclear Information System (INIS)

Duret, F.; Dutzer, M.; Beranger, V.; Lecoq, P.

2003-01-01

Extension of dismantling operations in France in the years to come poses the question of availability of long-term waste facility. Large amount of such wastes will be produced after progressive shutdown of the 58 pressurized water reactors now in operation, not before 2010. However, France is already confronted with dismantling of 9 power reactors (6 of which of gas cooled graphite type), the first reprocessing plant at Marcoule, as well as, dismantling of other installations, for instance the CEA reactors or laboratories. The systems of processing the dismantling waste are not different from those used for wastes resulting from nuclear operations. For the high-level or long-term intermediate level activity disposal the debates must start by 2006, as based on the results of the research conducted according to different provisions of the December 30, 1991 law. These wastes represent however small amounts from the dismantling (around 2000 t for the 9 reactors at shutdown) and they will be stored until a decision will be made. A specific storing system should be implemented by 2008-2010 for the graphite wastes (around 23,000 t) which contain significant amount of long-lived radioelements, although their gross activity is low. But the most significant amount will come from low-level or intermediate-level of short lifetime or from wastes of very low activity. The first category is stored at Storage Center at Aube (CSA), its capacity being of 1,000,000 m 3 of drums. The total volume stored by the end of 2002 amounted 136,500 m 3 with an annual delivering of 12-15,000 m 3 at design rate of 30,000 m 3 /y. This center will be able to absorb the flux increase resulting from dismantling of the decommissioned nuclear installations (around 50,000 t from the dismantling of the 9 power reactor). The Center at Aube can be also adapted for storing wastes of large sizes as for instance the lid of the reactor vessel. According to the French regulation, the wastes produced within a

Brennilis, laboratory of dismantlement

International Nuclear Information System (INIS)

Dupin, L.

2011-01-01

This article comments some aspects of the dismantlement activity on the Brennilis site (in Brittany) where a heavy water reactor has been operated from 1966 to 1985. Half of the deconstruction work has been performed between 1996 and 2006. As the model proposed by EDF for this operation raised some questions, works have been stopped for a while, until July 2011 when a decree authorized them again, but for some parts of the site only. The reactor block must wait as no technical solution exists for storage. But, the experience from this site will be used for eight other first generation power plants

Decontamination and dismantlement plan for international reviewing

International Nuclear Information System (INIS)

Wells, P.B.; Earle, O.K.; Klepikov, A.Kh.

2000-01-01

When developing a decommissioning plan, several factors need to be included. First and foremost is the issue of outline and scope. Specific to the BN-350, are issues related to short term tasks required to support the safe storage of the reactor for the next 50 years, and long term tasks required to dismantle the reactor, leaving some sort of final state, (brown field, green field, etc.) In addition, issues such as personnel and physical safety as well as environmental concerns must be addressed to ensure the shut down and dismantlement of the reactor is done in a safe manner, both for personnel and the environment. In addition to being the base document in which to support work, a D and D plan can also be utilized to obtain financial resources necessary to complete the plan, as is the case for the BN-350 Reactor located in Aktau, Kazakhstan. By providing a clear and complete D and D plan, which includes costs and schedules for each item, it is anticipated that donor countries will have the ability to review, approve, and provide financial support to complete the work described in the plan

Reactor vessel pressure transient protection for pressurized water reactors

International Nuclear Information System (INIS)

Zech, G.

1978-09-01

During the past few years the NRC has been studying the issue of protection of the reactor pressure vessels at Pressurized Water Reactors (PWRs) from transients when the vessels are at a relatively low temperature. This effort was prompted by concerns related to the safety margins available to vessel damage as a result of such events. Nuclear Reactor Regulation Category A Technical Activity No. A-26 was established to set forth the NRC plan for resolution of the generic aspects of this safety issue. The purpose of the report is to document the completion of this generic technical activity

Expertise of the Oeko-Institute on the application to obtain permission to partially dismantle the Niederaichbach nuclear power plant

International Nuclear Information System (INIS)

1985-01-01

This expertise gives an overview on the problems associated with the decommissioning and dismantling of the Niederaichbach nuclear power plant, considering technical and legal aspects. It wants to prove that the dismantling of this reactor cannot serve as evidence to prove the general feasibility of reactor dismantling. Much space is dedicated to the discussion about where the borderline should be drawn between radioactive and non-radioactive materials according to the ordinance on radiation protection. The reasons for rejecting the partial dismantling application are given. (DG) [de

Calculation of external exposure during transport and disposal of radioactive waste arisen from dismantling of steam generator

International Nuclear Information System (INIS)

Hornacek, M.; Necas, V.

2014-01-01

The dismantling of large components (reactor pressure vessel, reactor internals, steam generator) represents complex of processes involving preparation, dismantling, waste treatment and conditioning, transport and final disposal. To optimise all of these activities in accordance with the ALARA principle the prediction of the exposure of workers is an essential prerequisite. The paper deals with the calculation of external exposure of workers during transport and final disposal of heat exchange tubes of steam generator used in Slovak nuclear power plant V1 in Jaslovske Bohunice. The type of waste packages, the calculation models of truck and National Radioactive Waste Repository in Mochovce are presented. The detailed methodology of radioactive waste disposal is showed and the degree of influence of time decay (0, 5 and 10 years) on the radiological conditions during transport and disposal is studied. All of the results do not exceed the limits given in Slovak and international regulatory documents. (authors)

In-situ dismantling of plutonium-contaminated glove box

International Nuclear Information System (INIS)

Numata, Koji; Watanabe, Hisashi; Ishikawa, Hisashi; Miyo, Hiroaki; Ohtsuka, Katsuyuki

1980-01-01

A plutonium-contaminated glove box was dismantled along with the development of the treatment techniques for plutonium-bearing wastes. The objectives of this in-situ dismantling of the glove box are to reuse the Plutonium Fuel Fabrication Facility more efficiently, to reduce the volume of wastes generated during the dismantling, and to acquire dismantling techniques for decommissioning the Plutonium Fuel Fabrication Facility in the future. Prior to the dismantling works, a greenhouse for decontamination was installed, and the decontamination with surfactants was performed. Unremovable contamination was coated with paint. After this greenhouse was removed, the main greenhouse for dismantling and three greenhouses for contamination control were assembled. The main workers wearing protective devices engaged in dismantling works in the greenhouse. As the protective devices, anorak type PVC suits with air line masks, Howell type pressurized suits, and respirators were used. The tools used for the dismantling are a plasma cutter, an electric nibbler, an electric disk grinder, an electric circular saw and an electric jig saw. The results of the dismantling in-situ were compared with two previous cases of dismantling carried out by different procedures. In the case of in-situ dismantling, the volume of wastes was 1.6 - 1.8 m 3 /m 3 of glove box, and considerable reduction was realized. (Kako, I.)

The molten salt reactor option for beneficial use of fissile material from dismantled weapons

International Nuclear Information System (INIS)

Gat, U.; Engel, J.R.

1991-01-01

The Molten Salt Reactor (MSR) option for burning fissile fuel from dismantled weapons is examined and is found very suitable for the beneficial use of this fuel. MSRs can utilize any fissile fuel in continuous operation with no special modifications, as demonstrated in the Molten Salt Reactor Experiment. Thus, MSRs are flexible while maintaining their economy. Furthermore, MSRs require only a minimum of special fuel preparation. They can tolerate denaturing and dilution of their fuel. The size of fuel shipments can be determined to optimize safety and security-all of which supports nonproliferation and resists diversion. In addition, MSRs have inherent safety features that make them acceptable and attractive. They can burn fissile material completely or can convert it to other fuels. MSRs also have the potential for burning the actinides and delivering the waste in an optimal form, thus contributing to the solution of one of the major remaining problems in the deployment of nuclear power

Cutting Technology for Decommissioning of the Reactor Pressure Vessels in Nuclear Power Plants

International Nuclear Information System (INIS)

Jeong, Kwan Seong; Kim, Geun Ho; Moon, Jei Kwon; Choi, Byung Seon

2012-01-01

Lots of nuclear power plants have been decommissioned during the last 2 decades. An essential part of this work is the dismantling of the Reactor Pressure Vessel and its Internals. For this purpose a wide variety of different cutting technologies have been developed, adapted and applied. A detailed introduction to Plasma Arc cutting, Contact Arc Metal cutting and Abrasive Water Suspension Jet cutting is given, as it turned out that these cutting technologies are particularly suitable for these type of segmentation work. A comparison of these technologies including gaseous emissions, cutting power, manipulator requirements as well as selected design approaches are given. Process limits as well as actual limits of application are presented

Decontamination and radioactivity measurement on building surfaces related to dismantling of Japan power demonstration reactor (JPDR)

International Nuclear Information System (INIS)

Hatakeyama, Mutsuo; Tachibana, Mitsuo; Yanagihara, Satoshi

1997-12-01

In the final stage of dismantling activities for decommissioning a nuclear power plant, building structures have to be demolished to release the site for unrestricted use. Since building structures are generally made from massive reinforced concrete materials, it is not a rational way to treat all concrete materials arising from its demolition as radioactive waste. Segregation of radioactive parts from building structures is therefore indispensable. The rational procedures were studied for demolition of building structures by treating arising waste as non-radioactive materials, based on the concept established by Nuclear Safety Commission, then these were implemented in the following way by the JPDR dismantling demonstration project. Areas of the JPDR facilities are categorized into two groups : possibly contaminated areas, and possibly non-contaminated areas, based on the document of the reactor operation. Radioactivity on the building surfaces was then measured to confirm that the qualitative categorization is reasonable. After that, building surfaces were decontaminated in such a way that the contaminated layers were removed with enough margin to separate radioactive parts from non-radioactive building structures. Thought it might be possible to demolish the building structures by treating arising waste as non-radioactive materials, confirmation survey for radioactivity was conducted to show that there is no artificial radioactive nuclides produced by operation in the facility. This report describes the procedures studied on measurement of radioactivity and decontamination, and the results of its implementation in the JPDR dismantling demonstration project. (author)

Remote tool development for nuclear dismantling operations

International Nuclear Information System (INIS)

Craig, G.; Ferlay, J.C.; Ieracitano, F.

2003-01-01

Remote tool systems to undertake nuclear dismantling operations require careful design and development not only to perform their given duty but to perform it safely within the constraints imposed by harsh environmental conditions. Framatome ANP NUCLEAR SERVICES has for a long time developed and qualified equipment to undertake specific maintenance operations of nuclear reactors. The tool development methodology from this activity has since been adapted to resolve some very challenging reactor dismantling operations which are demonstrated in this paper. Each nuclear decommissioning project is a unique case, technical characterisation data is generally incomplete. The development of the dismantling methodology and associated equipment is by and large an iterative process combining design and simulation with feasibility and validation testing. The first stage of the development process involves feasibility testing of industrial tools and examining adaptations necessary to control and deploy the tool remotely with respect to the chosen methodology and environmental constraints. This results in a prototype tool and deployment system to validate the basic process. The second stage involves detailed design which integrates any remaining technical and environmental constraints. At the end of this stage, tools and deployment systems, operators and operating procedures are qualified on full scale mock ups. (authors)

Reactor pressure tank

International Nuclear Information System (INIS)

Dorner, H.; Scholz, M.; Jungmann, A.

1975-01-01

In a reactor pressure tank for a nuclear reactor, self-locking hooks engage a steel ring disposed over the removable cover of the steel vessel. The hooks exert force upon the cover to maintain the cover in a closed position during operation of the reactor pressure tank. The force upon the removal cover is partly the result of the increasing temperature and thermal expansion of the steel vessel during operation. The steel vessel is surrounded by a reinforced-concrete tank. (U.S.)

Pressure tube reactor

International Nuclear Information System (INIS)

Susuki, Akira; Murata, Shigeto; Minato, Akihiko.

1993-01-01

In a pressure tube reactor, a reactor core is constituted by arranging more than two units of a minimum unit combination of a moderator sealing pipe containing a calandria tube having moderators there between and a calandria tube and moderators. The upper header and a lower header of the calandria tank containing moderators are communicated by way of the moderator sealing tube. Further, a gravitationally dropping mechanism is disposed for injecting neutron absorbing liquid to a calandria gas injection portion. A ratio between a moderator volume and a fuel volume is defined as a function of the inner diameter of the moderator sealing tube, the outer diameter of the calandria tube and the diameter of fuel pellets, and has no influence to intervals of a pressure tube lattice. The interval of the pressure tube lattice is enlarged without increasing the size of the pressure tube, to improve production efficiency of the reactor and set a coolant void coefficient more negative, thereby enabling to improve self controllability and safety. Further, the reactor scram can be conducted by injecting neutron absorbing liquid. (N.H.)

Importance of low-level radioactive wastes in dismantling strategy in CEA (FRANCE)

International Nuclear Information System (INIS)

Lafaille, C.

1991-01-01

This paper describes the advance used in C.E.A. to realize dismantling operations in the best technical and economical conditions. Particularly, for low-level radioactive waste management CEA's advance defines, first, the final destination of dismantling materials: - recycling in public lands for level activity inferior to 1 Bq/g; directly or after transformation (melting, calcination, extrusion) - storage in a ground disposal, after compacting, encapsulation or drumming. Two examples are given: - Marcoule G2 - G3 reactor dismantling - Gaseous diffusion plants demolition (COGEMA Pierrelatte)

Dismantling of the research reactor RTS-1 Galileo Galilei in Pisa (Italy)

International Nuclear Information System (INIS)

Ruiz Martinez, J. t.; Farella, G.; Cimini, E.; Russo, M.

2014-01-01

This paper is about the most relevant aspects of the first phase of the dismantling, removal of the water in the pool, prior treatment through evaporation, the dismantling of all the submerged activated elements and other activated or contaminated elements that have been part of the nuclear facility. (Author)

Evaluation of worker's dose on a virtual dismantling environment

International Nuclear Information System (INIS)

Park, Hee Seong; Kim, Sung Hyun; Park, Byung Suk; Yoon, Ji Sup

2007-01-01

The motivation of this study is to provide a basis for a minimization of worker's dose during dismantling activities. In the present study, we proposed methods for identifying an existence of radioactivity which is contained in the dismantling objects and for evaluating a worker's dose under a virtual dismantling environment. To evaluate a worker's external dose, the shape of the exposure room in the KRR 2(Korean Research Reactor TRIGA MARK III) by 3D CAD was created and the radiation dose surrounding the facility by using MCNP- 4C(Monte Carlo N-Particle-4C) was calculated. The radiation field of the exposure room was visualized three dimensionally by using the radiation dose that was obtained by the code

Pressurized-water reactors

International Nuclear Information System (INIS)

Bush, S.H.

1983-03-01

An overview of the pressurized-water reactor (PWR) pressure boundary problems is presented. Specifically exempted will be discussions of problems with pumps, valves and steam generators on the basis that they will be covered in other papers. Pressure boundary reliability is examined in the context of real or perceived problems occurring over the past 5 to 6 years since the last IAEA Reliability Symposium. Issues explicitly covered will include the status of the pressurized thermal-shock problem, reliability of inservice inspections with emphasis on examination of the region immediately under the reactor pressure vessel (RPV) cladding, history of piping failures with emphasis on failure modes and mechanisms. Since nondestructive examination is the topic of one session, discussion will be limited to results rather than techniques

Reactor pressure boundary materials

International Nuclear Information System (INIS)

Hong, Jun Hwa; Chi, S. H.; Lee, B. S.

2002-04-01

With a long-term operation of nuclear power plants, the component materials are degraded under severe reactor conditions such as neutron irradiation, high temperature, high pressure and corrosive environment. It is necessary to establish the reliable and practical technologies for improving and developing the component materials and for evaluating the mechanical properties. Especially, it is very important to investigate the technologies for reactor pressure boundary materials such as reactor vessel and pipings in accordance with their critical roles. Therefore, this study was focused on developing and advancing the microstructural/micro-mechanical evaluation technologies, and on evaluating the neutron irradiation characteristics and radiation effects analysis technology of the reactor pressure boundary materials, and also on establishing a basis of nuclear material property database

The challenges of dismantling

International Nuclear Information System (INIS)

Sene, Monique; Lheureux, Yves; Leroyer, Veronique; Rollinger, Francois; Gauthier, Florence; Depauw, Denis; Reynal, Nathalie; Fraysse, Thierry; Burger, Eric; Bertrand, Adrien; Vallat, Christophe; Bernet, Philippe; Eimer, Michel; Boutin, Dominique; Bietrix, Philippe; Richard, Francoise; Piketty, Laurence; Mouchet, Chantal; Charre, Jean-Pierre

2014-01-01

This document gathers Power Point presentations which address the contexts and challenges of dismantling (legal framework, safety and radiation protection challenges, waste processing industry), and propose illustrations of dismantling challenges (example of operations to prepare EURODIF dismantling and CLIGEET work-group on EURODIF dismantling, examples of dismantling of EDF installations and CLIs' opinion on the dismantling of EDF installations, Brennilis dismantling follow-up performed by the CLI, examples of dismantling of CEA installations and opinion of a CLI on the dismantling of CEA installations)

Dismantling of the 50 MW steam generator test facility

International Nuclear Information System (INIS)

Nakai, S.; Onojima, T.; Yamamoto, S.; Akai, M.; Isozaki, T.; Gunji, M.; Yatabe, T.

1997-01-01

We have been dismantling the 50MW Steam Generator Test Facility (50MWSGTF). The objectives of the dismantling are reuse of sodium components to a planned large scale thermal hydraulics sodium test facility and the material examination of component that have been operated for long time in sodium. The facility consisted of primary sodium loop with sodium heater by gas burner as heat source instead of reactor, secondary sodium loop with auxiliary cooling system (ACS) and water/steam system with steam temperature and pressure reducer instead of turbine. It simulated the 1 loop of the Monju cooling system. The rated power of the facility was 50MWt and it was about 1/5 of the Monju power plant. Several sodium removal methods are applied. As for the components to be dismantled such as piping, intermediate heat exchanger (IHX), air cooled heat exchangers (AC), sodium is removed by steam with nitrogen gas in the air or sodium is burned in the air. As for steam generators which material tests are planned, sodium is removed by steam injection with nitrogen gas to the steam generator. The steam generator vessel is filled with nitrogen and no air in the steam generator during sodium removal. As for sodium pumps, pump internal structure is pulled out from the casing and installed into the tank. After the installation, sodium is removed by the same method of steam generator. As for relatively small reuse components such as sodium valves, electromagnet flow meters (EMFs) etc., sodium is removed by alcohol process. (author)

Dismantling and waste management: CEA's strategy and research programs

International Nuclear Information System (INIS)

Behar, C.

2012-01-01

There are 3 main dismantling operations in CEA. First, the dismantling of the UP1 facility in the Marcoule site. UP1 was a reprocessing plant of nuclear fuels that operated from 1958 to 1997 and is now the biggest dismantling operation in the world. Its dismantling operation follows a 6-step scheme that will end in 2050. Secondly, the Passage project on the Grenoble site that concerns the dismantling of 3 research reactors (Siloette, Melusine and Siloe), of a laboratory dedicated to the analysis of active materials (Lama) and of a station for the processing of waste (Sted). Thirdly the Aladin project that concerns the installations of the Fontenay-aux-Roses site. The dismantling operations are complex because all the first research programs on high activity chemistry and on transuranium elements were performed in Fontenay-aux-Roses facilities and because ancient activities have to leave a clean place to be replaced by new ones. The radioactive waste produced by CEA enter the flow of waste that is normally processed and managed by ANDRA. Only high-activities waste have not yet a definitive solution, they are stored in waiting the opening of a geological repository. CEA leads research programs on the separation and transmutation of minor actinides and on the long-term behaviour of waste packages put in deep geological layers. (A.C.)

The dismantling of the damaged Chernobyl reactor No 4 and the implications upon the design of a second shelter

International Nuclear Information System (INIS)

Mao, J.L. Le; White, S.J.

1995-01-01

During 1994/95 a study was undertaken, by Alliance, to assess the feasibility of constructing a new containment/shelter over the damaged Chernobyl reactor and its sarcophagus. This paper reviews the implications placed upon the design due to the ultimate dismantling requirements. The paper highlights some of the generic requirements and the impact upon the shelter design solution. Alliance is a consortium of leading European engineering companies comprising Campenon Bernard, AEA Technology, Walter-Bau, SGN, Taylor Woodrow and Bouygues. (Author)

Reactor water spontaneous circulation structure in reactor pressure vessel

International Nuclear Information System (INIS)

Takahashi, Kazumi

1998-01-01

The gap between the inner wall of a reactor pressure vessel of a BWR type reactor and a reactor core shroud forms a down comer in which reactor water flows downwardly. A feedwater jacket to which feedwater at low temperature is supplied is disposed at the outer circumference of the pressure vessel just below a gas/water separator. The reactor water at the outer circumferential portion just below the air/water separator is cooled by the feedwater jacket, and the feedwater after cooling is supplied to the feedwater entrance disposed below the feedwater jacket by way of a feedwater introduction line to supply the feedwater to the lower portion of the down comer. This can cool the reactor water in the down comer to increase the reactor water density in the down comer thereby forming strong downward flows and promote the recycling of the reactor water as a whole. With such procedures, the reactor water can be recycled stably only by the difference of the specific gravity of the reactor water without using an internal pump. In addition, the increase of the height of the pressure vessel can be suppressed. (I.N.)

Underwater-manipulation system for measuring- and cutting tasks in dismantling decommissioned nuclear facilities. Final report

International Nuclear Information System (INIS)

Stegemann, D.; Reimche, W.; Hansch, M.; Spitzer, M.

1995-01-01

Not only manipulators are necessary for dismantling and inspection of structure parts in decomissioned nuclear facilities, but flexible underwater-vehicles. Free-diving underwater-vehicles for inspection and dismantling tasks are still not developed and tested. Aim of the project is the development of sensors and devices for the position determination and the depth regulation. For inspection tasks an ultrasonic measurement and dosimeter device shall be built up. A measurement device has been developed which evaluates the ultrasonic time of flight from a transmitter at the vehicle to several receivers, installed in the reactor pressure vessel. The depth regulation is based on a pressure sensor and the direct control of the thrusters. The ultrasonic measurements are realized by an adapted ultrasonic card, the γ-dosimetry with an ionization chamber and a pA-amplifier. An acoustic orientation system was built up, which measures very accurately with one transmitter mounted on the vehicle and four receivers. Problem occur by reflection from the walls of the basin. The depth regulation is working faultless. The ultrasonic device is preferably used for distance measurement. The radiation measurement device was tested and mounted in the vehicle. (orig./HP) [de

Declassification of radioactive water from a pool type reactor after nuclear facility dismantling

Science.gov (United States)

Arnal, J. M.; Sancho, M.; García-Fayos, B.; Verdú, G.; Serrano, C.; Ruiz-Martínez, J. T.

2017-09-01

This work is aimed to the treatment of the radioactive water from a dismantled nuclear facility with an experimental pool type reactor. The main objective of the treatment is to declassify the maximum volume of water and thus decrease the volume of radioactive liquid waste to be managed. In a preliminary stage, simulation of treatment by the combination of reverse osmosis (RO) and evaporation have been performed. Predicted results showed that the combination of membrane and evaporation technologies would result in a volume reduction factor higher than 600. The estimated time to complete the treatment was around 650 h (25-30 days). For different economical and organizational reasons which are explained in this paper, the final treatment of the real waste had to be reduced and only evaporation was applied. The volume reduction factor achieved in the real treatment was around 170, and the time spent for treatment was 194 days.

EDV supported dynamic fire protection concept adaptation during dismantling of nuclear facilities

International Nuclear Information System (INIS)

Mummert, Maxi; Traichel, Anke; Dilger, Matthias

2013-01-01

Fire protection concepts are supposed to be a decision guide for the definition of measures and priorities in fire fighting and fire prevention. In case of reactor dismantling a fire protection concept for the actual status is required. Following the fuel removal from the reactor the protection goals are reduced to the safe confinement of radioactive materials and the restriction of radiation exposure. A dynamic fire protection concept was developed to allow the compliance with the required protection measures with respect to the protection targets. The implementation of the dynamic fire protection concept simplifies the planning of the dismantling steps and to adjust the fire protection measured in the frame of changes in the plant.

Evaluation of Pressure Changes in HANARO Reactor Hall after a Reactor Shutdown

International Nuclear Information System (INIS)

Han, Geeyang; Han, Jaesam; Ahn, Gukhoon; Jung, Hoansung

2013-01-01

The major objective of this work is intended to evaluate the characteristics of the thermal behavior regarding how the decay heat will be affected by the reactor hall pressure change and the increase of pool water temperature induced in the primary coolant after a reactor shutdown. The particular reactor pool water temperature at the surface where it is evaporated owing to the decay heat resulting in the local heat transfer rate is related to the pressure change response in the reactor hall associated with the primary cooling system because of the reduction of the heat exchanger to remove the heat. The increase in the pool water temperature is proportional to the heat transfer rate in the reactor pool. Consequently, any limit on the reactor pool water temperature imposes a corresponding limit on the reactor hall pressure. At HANARO, the decay heat after a reactor shutdown is mainly removed by the natural circulation cooling in the reactor pool. This paper is written for the safety feature of the pressure change related leakage rate from the reactor hall. The calculation results show that the increase of pressure in the reactor hall will not cause any serious problems to the safety limits although the reactor hall pressure is slightly increased. Therefore, it was concluded that the pool water temperature increase is not so rapid as to cause the pressure to vary significantly in the reactor hall. Furthermore, the mathematical model developed in this work can be a useful analytical tool for scoping and parametric studies in the area of thermal transient analysis, with its proper representation of the interaction between the temperature and pressure in the reactor hall

Development of telerobotic systems for reactor decommissioning, (3)

International Nuclear Information System (INIS)

Usui, Hozumi; Fujii, Yoshio; Shinohara, Yoshikuni

1991-01-01

This paper describes the telerobotic system for reactor decommissioning in the scope of engineering demonstration of dismantling radioactive reactor internals of an experimental boiling water power reactor JPDR. The total system consists of a telerobotic manipulator system equipped with a multi-functional amphibious slave manipulator with a load capacity of 25 daN, a chain-driven transport system, and a computer-assisted monitoring and control system. Preceding to the application of the telerobotic system to actual dismantling operation, a mockup test was performed of dismantling the simulated reactor internals of actual-size by the method of underwater plasma arc cutting in order to study the performance of the telerobotic system in a realistic environment. The system was then successfully applied to dismantling the actual reactor internals according to the JPDR decommissioning program. (author)

Chapter 12. Nullification of nuclear reactors

International Nuclear Information System (INIS)

Toelgyessy, J.; Harangozo, M.

2000-01-01

This is a chapter of textbook of radioecology for university students. In this chapter authors deal with problems connected with nullification of nuclear reactors. There are tree basic methods of nullification of nuclear reactors: (1) conservation, (2) safe close (wall up, embed in concrete), (3) direct dismantlement and remotion and two combined ways: (1) combination of mothball with subsequent dismantlement and remotion and (2) combination of safe close with subsequent dismantlement and remotion. Activity levels as well as volumes of radioactive wastes connected with decommissioning of nuclear reactors are reviewed

The preliminary 3D dynamic simulation on the RSR dismantling process of the KRR-1 and 2

International Nuclear Information System (INIS)

Kim, Hee-Reyoung; Kim, Sung-Kyun; Seo, Bum-Kyoung; Lee, Kune-Woo; Park, Jin-Ho

2003-01-01

A three-dimensional graphic simulation has been carried out for the dismantling process of the Rotary Specimen Rack(RSR) in the Korea Research Reactor-1 and 2 (KRR-1 and 2). First of all, the general steps of the graphic simulation were established and reviewed for the dismantling process of the object. Four dismantling processes, which are the removal of RSR, reactor core region, beam tube, and thermal column and activated concrete, were selected for the graphic simulation on the virtual space by the consideration of the activation, worker training, work difficulty and so on. In the present study, the dismantling procedure of the RSR was divided into several steps and its visual simulation was performed by the 3D graphic software. Finally, the simulation result was converted to moving file with extension of AVI so that easy approach can be made on window OS system

Decommissioning of Salaspils nuclear reactor

International Nuclear Information System (INIS)

Abramenkovs, A.; Malnachs, J.; Popelis, A.

2002-01-01

In May 1995, the Latvian Government decided to shut down the Research Reactor Salaspils (SRR) and to dispense with nuclear energy in future. The reactor has been out of operation since July 1998. A conceptual study for the decommissioning of SRR has been carried out by Noell-KRC-Energie- und Umwelttechnik GmbH from 1998-1999. he Latvian Government decided on 26 October 1999 to start the direct dismantling to 'green field' in 2001. The results of decommissioning and dismantling performed in 1999-2001 are presented and discussed. The main efforts were devoted to collecting and conditioning 'historical' radioactive waste from different storages outside and inside the reactor hall. All radioactive material more than 20 tons were conditioned in concrete containers for disposal in the radioactive waste depository 'Radons' in the Baldone site. Personal protective and radiation measurement equipment was upgraded significantly. All non-radioactive equipment and material outside the reactor buildings were free-released and dismantled for reuse or conventional disposal. Weakly contaminated material from the reactor hall was collected and removed for free-release measurements. The technology of dismantling of the reactor's systems, i.e. second cooling circuit, zero power reactors and equipment, is discussed in the paper. (author)

Plan for Moata reactor decommissioning, ANSTO

International Nuclear Information System (INIS)

Kim, S.

2003-01-01

'Moata' is an Argonaut type 100 kW reactor that was operated by Australian Nuclear Science and Technology Organisation for 34 years from 1961 to 1995. It was initially used as a reactor-physics research tool and a training reactor but the scope of operations was extended to include activation analysis and neutron radiography from the mid 1970s. In 1995, the Moata reactor was shutdown on the grounds that its continued operation could no longer be economically justified. All the fuel (HEU) was unloaded to temporary storage and secured in 1995, followed by drainage of the demineralised water (primary coolant) from the reactor in 1996 and complete removal of electrical cables in 1998. The Reactor Control Room has been renovated into a modern laboratory. The reactor structure is still intact and kept under safe storage. Various options for decommissioning strategies have been considered and evaluated. So far, 'Immediate Dismantling' is considered to be the most desirable option, however, the timescale for actual dismantling needs to take account of the establishment of the national radioactive repository. This paper describes the dismantling options and techniques considered along with examples of other dismantling projects overseas. (author)

EDF's dismantling experience

International Nuclear Information System (INIS)

Mira, J.J.

1993-01-01

The dismantling policy at EDF, taking into account technical, economical and socio-political factors, is presented. The various current realizations are reviewed and their dismantling solution discussed: Chinon A2, Chinon A1, Marcoule G1, G2, G3, Brennilis (EL4). Several dismantling projects are also described (Chinon A3, St-Laurent A1-A2, Chooz A). The various dismantling operations are presented and scheduled

Some aspects of reactor pressure vessel integrity

International Nuclear Information System (INIS)

Korosec, D.; Vojvodic, G.J.

1996-01-01

Reactor pressure vessel of the pressurized water reactor nuclear power plant is the subject of extreme interest due to the fact that presents the pressure boundary of the reactor coolant system, which is under extreme thermal, mechanical and irradiation effects. Reactor pressure vessel by itself prevents the release of fission products to the environment. Design, construction and in-service inspection of such component is governed by strict ASME rules and other forms of administrative control. The reactor pressure vessel in nuclear power plant Kriko is designed and constructed in accordance with related ASME rules. The in-service inspection program includes all requests presented in ASME Code section XI. In the present article all major requests for the periodic inspections of reactor pressure vessel and fracture mechanics analysis are discussed. Detailed and strict fulfillment of all prescribed provisions guarantee the appropriate level of nuclear safety. (author)

Dismantling of nuclear facilities

International Nuclear Information System (INIS)

Tallec, M.; Kus, J.P.

2009-01-01

Nuclear facilities have a long estimable lifetime but necessarily limited in time. At the end of their operation period, basic nuclear installations are the object of cleansing operations and transformations that will lead to their definitive decommissioning and then to their dismantling. Because each facility is somewhere unique, cleansing and dismantling require specific techniques. The dismantlement consists in the disassembly and disposing off of big equipments, in the elimination of radioactivity in all rooms of the facility, in the demolition of buildings and eventually in the reconversion of all or part of the facility. This article describes these different steps: 1 - dismantling strategy: main de-construction guidelines, expected final state; 2 - industries and sites: cleansing and dismantling at the CEA, EDF's sites under de-construction; 3 - de-construction: main steps, definitive shutdown, preparation of dismantling, electromechanical dismantling, cleansing/decommissioning, demolition, dismantling taken into account at the design stage, management of polluted soils; 4 - waste management: dismantlement wastes, national policy of radioactive waste management, management of dismantlement wastes; 5 - mastery of risks: risk analysis, conformability of risk management with reference documents, main risks encountered at de-construction works; 6 - regulatory procedures; 7 - international overview; 8 - conclusion. (J.S.)

Contaminated Metal Components in Dismantling by Hot Cutting Processes

International Nuclear Information System (INIS)

Cesari, Franco G.; Conforti, Gianmario; Rogante, Massimo; Giostri, Angelo

2006-01-01

During the preparatory dismantling activities of Caorso's Nuclear Power Plant (NPP), an experimental campaign using plasma and oxyacetylene metal cutting processes has been performed and applied to plates and tubes exposed to the coolant steam of the reactor. The plant (Boiling Water Reactor, 870 MWe) was designed and built in the 70's, and it was fully operating by 1981 to 1986 being shut down after 1987 Italy's poll that abrogated nuclear power based on U235 fission. The campaign concerns no activated materials, even if the analyses have been performed of by use contaminated components under the free release level, not yet taking into account radioactivity. In this paper, the parameters related to inhalable aerosol, solid and volatile residuals production have been, studied during hot processes which applies the same characteristics of the cutting in field for the dismantling programs of Caorso NPP. The technical parameters such as cutting time and cutting rate vs. pipe diameter/thickness/schedule or plate thickness for ferritic alloys and the emissions composition coming from the sectioning are also reported. The results underline the sort of trouble that can emerge in the cutting processes, in particular focusing on the effects comparison between the two cutting processes and the chemical composition of powders captured by filtering the gaseous emission. Some preliminary considerations on methodology to be used during the dismantling have been presented. (authors)

Study on safety evaluation for unrestricted recycling criteria of radioactive waste from dismantling operation

International Nuclear Information System (INIS)

Yoshimori, Michiro; Ohkoshi, Minoru; Abe, Masayoshi

1995-01-01

The study on safety evaluation was done, under contracting with the Science and Technology Agency, for recycling scrap metal arising from dismantling of reactor facilities. An object of this study is to contribute to the examination of establishing criteria and safety regulation for unrestricted recycling steel scrap. To define amount of market flow of iron material in Japan and the amount of radioactive waste generated from dismantling of reactor facilities, investigation had been carried out. On basis of these investigation results and data in several literature, individual doses to workers and to the members of the public have been calculated as well as collective doses. (author)

Pressure releasing device for reactor container

International Nuclear Information System (INIS)

Takeda, Mika.

1994-01-01

In the present invention, dose rate to public caused by radioactive rare gases can be decreased. That is, a reactor container contains a reactor pressure vessel incorporating a reactor core. There are disposed a pressure releasing system for releasing the pressure in the reactor pressure vessel to the outside, and a burning device for burning gases released from the pressure releasing system. An exhaustion pipe is disposed to the pressure releasing system. A burning device is disposed to the exhaustion pipe. It is effective to dispose a ventilation port at a portion of the exhaustion pipe upstream of the burning device. In addition, the burning device may preferably be disposed in a multi-stage in the axial direction of the exhaustion pipe. With such procedures, hydrogen in gases discharged along with the release of the pressure in the container is burned. Buoyancy is caused to the exhaustion gases by heat energy upon burning. Since the exhaustion gases can reach a higher level by the buoyancy, the dose rate due to the rare gases can be reduced. (I.S.)

Reactor pressure vessel design

International Nuclear Information System (INIS)

Foehl, J.

1998-01-01

As a result of the popularity of the Agencies report 'Neutron Irradiation Embrittlement of Reactor Pressure Vessel Steels' of 1975, it was decided that another report on this broad subject would be of use. In this report, background and contemporary views on specially identified areas of the subject are considered as self-contained chapters, written by experts. In chapter 2, the general principles of reactor pressure vessel design are elaborated. Crack and fracture initiation and propagation are treated in some detail

Nuclear cleanup and decontamination for dismantling operations

International Nuclear Information System (INIS)

Bargues, S.; Solignac, Y.; Lapierre, Y.

2003-01-01

In the May 2003 issue of the review 'Controle', the French Nuclear Safety Authority (Autorite de Surete Nucleaire or ASN) reviewed the radiation protection and waste management principles applicable to dismantling operations carried out on nuclear installations, i.e. reactors, research laboratories, fuel cycle installations and nuclear power reactors. Estelle Chapelain, of the DGSNR (French General Directorate for Nuclear Safety and Radiation Protection), pointed out that dismantling work does not involve the same radioactive risks as operating an installation. For instance, 'the risk of disseminating radioactive material is generally greater because the dismantling process supposes the removal of one or more containment barriers'. In addition to this risk of internal exposure, the possibility of external irradiation of personnel must be taken into account due to the nature of the work carried out by the operators. The probability of conventional hazards is also accentuated, these hazards varying as work progresses (fire hazards during cutting operations, hazards associated with handling tasks, etc). Other risks must also be considered: hazards due to the ageing of installations, to loss of traceability, and finally the risks associated with waste management. Waste management falls within a strict regulatory framework specified by the decree dated December 31, 1999, which makes it compulsory to carry out a 'waste survey' with the aim of producing an inventory of waste and improving waste management. These surveys include 'waste zoning' to identify those areas liable to have been contaminated. These requirements lead operators to adapt their cleanup methodology in order to distinguish suspect rooms or equipment from those that can be deemed with certainty to be conventional. In its conclusion, the safety authority recalls the importance of 'the safety and radiation protection of dismantling operations being effectively managed and optimised, without imposing

Decommissioning strategy for reactor AM, Russian Federation

International Nuclear Information System (INIS)

Suvorov, A.P.; Mukhamadeev, R.I.

2002-01-01

This paper presents the results of studies into the various aspects of decommissioning the oldest Russian research reactor, the AM reactor. Experimental and calculation results of a study to determine the inventory of long lived radioactive materials at the AM reactor are presented, along with a comparison to comparable data for other similar reactors. An analysis, by calculation, of the decay time needed to allow manual dismantling of the reactor vessel and stack, without remote operated equipment, defined it as 90 years. The possibility of burning most of the irradiated graphite to decrease the amount of long lived radioactive wastes was confirmed. The problems associated with the dismantling of the reactor components, contaminated with radioactive corrosion products, were analyzed. A decommissioning strategy for reactor AM was formed which is deferred dismantling, placing most of the radiological areas into long term safe enclosure. An overall decommissioning plan for reactor AM is given. (author)

Nuclear reactor fuel sub-assemblies

International Nuclear Information System (INIS)

Ford, J.; Bishop, J.F.W.

1981-01-01

An improved fuel sub-assembly for liquid metal cooled fast breeder nuclear reactors is described which facilitates dismantling operations for reprocessing purposes. The method of dismantling is described. (U.K.)

Behavior of generated aerosols in decommissioning of reactor

International Nuclear Information System (INIS)

Tomii, H.; Nakamura, K.

1999-01-01

Generated aerosols in dismantling of the JPDR were investigated for making an estimation of air contamination. The maximum dose equivalent rate at the surface of each reactor component was 9.4 Sv/h for core shroud, 80 mSv/h for pressure vessel, 2.0 mSv/h for biological shield, respectively. An under-water cutting method with remote handling plasma torch was used for dismantling of the core shroud and the pressure vessel. The biological shield was dismantled by an in-air cutting method and a controlled blasting method. Pipes connected to recirculation system were dismounted by a conventional mechanical and thermal cutting machine in the air. Generated radioactive aerosols were collected in the exhaust air of green house which enclosed the upper part of the reactor room to control the air contamination. An Andersen sampler was used for the measurement of particle distribution in the aerosols. Most of the particle size was below 0.1 μm in the under-water cutting method. The particle size distribution in the in-air cutting method, however, was divided into two parts at 0.1 μm and 0.3 μm. Dispersion rate of aerosol into the atmosphere was decreased exponentially with the depth of water. The dispersion rate and the size distribution of aerosol generated during cutting of the stainless steel pipes and blasting of the biological shield are also reported in the paper. (Suetake, M.)

Fundamentals of pressurized water reactors

International Nuclear Information System (INIS)

Murray, L.

1982-01-01

In many countries, the pressurized water reactor (PWR) is the most widely used, even though it requires enrichment of the uranium to about 3% in U-235 and the moderator-coolant must be maintained at a high pressure, about 2200 pounds per square inch. Our objective in this series of seven lectures is to describe the design and operating characteristics of the PWR system, discuss the reactor physics methods used to evaluate performance, examine the way fuel is consumed and produced, study the instrumentation system, review the physics measurements made during initial startup of the reactor, and outline the administrative aspects of starting up a reactor and operating it safely and effectively

Pressure Tube and Pressure Vessel Reactors; certain comparisons

Energy Technology Data Exchange (ETDEWEB)

Margen, P H; Ahlstroem, P E; Pershagen, B

1961-04-15

In a comparison between pressure tube and pressure vessel type reactors for pressurized D{sub 2}O coolant and natural uranium, one can say that reactors of these two types having the same net electrical output, overall thermal efficiency, reflected core volume and fuel lattice have roughly the same capital cost. In these circumstances, the fuel burn-up obtainable has a significant influence on the relative economics. Comparisons of burn-up values made on this basis are presented in this report and the influence on the results of certain design assumptions are discussed. One of the comparisons included is based on the dimensions and ratings proposed for CANDU. Moderator temperature coefficients are compared and differences in kinetic behaviour which generally result in different design philosophies for the two types are mentioned, A comparison of different methods of obtaining flux flattening is presented. The influence of slight enrichment and other coolants, (boiling D{sub 2}O and gases) on the comparison between pressure tube and pressure vessel designs is discussed and illustrated with comparative designs for 400 MW electrical output. This paper was presented at the EAES Enlarged Symposium on Heterogeneous Heavy Water Power Reactors, Mallorca, October 10 - 14, 1960.

Pressure Tube and Pressure Vessel Reactors; certain comparisons

International Nuclear Information System (INIS)

Margen, P.H.; Ahlstroem, P.E.; Pershagen, B.

1961-04-01

In a comparison between pressure tube and pressure vessel type reactors for pressurized D 2 O coolant and natural uranium, one can say that reactors of these two types having the same net electrical output, overall thermal efficiency, reflected core volume and fuel lattice have roughly the same capital cost. In these circumstances, the fuel burn-up obtainable has a significant influence on the relative economics. Comparisons of burn-up values made on this basis are presented in this report and the influence on the results of certain design assumptions are discussed. One of the comparisons included is based on the dimensions and ratings proposed for CANDU. Moderator temperature coefficients are compared and differences in kinetic behaviour which generally result in different design philosophies for the two types are mentioned, A comparison of different methods of obtaining flux flattening is presented. The influence of slight enrichment and other coolants, (boiling D 2 O and gases) on the comparison between pressure tube and pressure vessel designs is discussed and illustrated with comparative designs for 400 MW electrical output. This paper was presented at the EAES Enlarged Symposium on Heterogeneous Heavy Water Power Reactors, Mallorca, October 10 - 14, 1960

The dismantling of nuclear installations

International Nuclear Information System (INIS)

Lacoste, A.C.; Duthe, M.; Mignon, H.; Lambert, F.; Pradel, Ph.; Hillewaere, J.P.; Dupre la Tour, St.; Mandil, C.; Weil, L.; Eickelpasch, N.; Finsterwalder, L.

1997-01-01

for nuclear installations, the dismantling is an important part of their exploitation. The technology of dismantling is existing and to get a benefit from the radioactive decay, it seems more easy for operating company such E.D.F. to wait for fifty years before dismantling. But in order to get the knowledge of this operation, the Safety Authority wanted to devote this issue of 'Controle'to the dismantling method. This issue includes: the legal aspects, the risks assessment, the dismantling policy at E.D.F., the site of Brennilis (first French experience of dismantling), the dismantling techniques, the first dismantling of a fuel reprocessing plant, comparison with classical installations, economic aspect, some German experiences, the cleansing of the american site of Handford. (N.C.)

Pressure tube type research reactor

International Nuclear Information System (INIS)

Ueda, Hiroshi.

1975-01-01

Object: To permit safe and reliable replacement of primary pipes by providing a reactor container so as to surround a pressure pipe, with upper portions of the two separably coupled together, and coupling the pressure pipe and primary piping by joint coupling above and below the reactor container, with the lower coupling joint surrounded by drain receptacle. Structure: At the time of replacement of a pressure pipe, a partition valve is opened to exhaust primary cooling water within pressure pipe and upper and lower portions of the primary piping and replace the decelerator within the reactor container with water of the same quality as that of pool water within an upper shield pool. Thereafter, the entire space above the drain receptacle is filled with pool water by closing a partition valve and opening a water supply valve. Then, upper portion seal cover, pool bottom lid, upper joint and upper portion primary piping are removed, then bolts and nuts are loosened, and the pressure pipe is taken out together with the shield block. (Kamimura, M.)

Further retardation could lead to a hold-up of nuclear reactor dismantling; Weitere Verzoegerungen koennten zu einem Stillstand des Kernkraft-Rueckbaus fuehren

Energy Technology Data Exchange (ETDEWEB)

Graf, Konstantin (comp.) [Innovations- und Technologieberatung Altran, Frankfurt am Main (Germany). Bereich Energy and Industry

2015-07-01

The following issues concerning the consequences of the German nuclear power phaseout are discussed: the cost of reactor dismantling could increase; the complete deconstruction of a nuclear power plant including environmental revitalization take a time of 10-15 years; the largest challenge is the still unsolved problem of final disposal; further retardations could trigger a complete deadlock of the deconstruction due to completely filled interim storage facilities. A further problem is the knowledge preservation due to the lack of students.

Development of decommissioning engineering support system for fugen. Development of support system during actual dismantlement works

International Nuclear Information System (INIS)

Masanori Izumi; Yukihiro Iguchi; Yoshiki Kannehira

2005-01-01

The Advanced Thermal Reactor, Fugen Nuclear Power Station was permanently shut down in March 2003, and is now preparing for decommissioning. We have been developing Decommissioning Engineering Support System (DEXUS) aimed at planning optimal dismantlement process and carrying out dismantlement work safely and precisely. DEXUS consists of 'decommissioning planning support system' and 'dismantling support system'. The dismantling support system is developed aiming at using during actual dismantling work. It consists of three subsystems such as 'Worksite Visualization System', 'Dismantling Data Collection System' and 'Generated Waste Management System'. 'Worksite Visualization System' is a support system designed to provide the necessary information to workers during actual dismantlement works. And this system adopts AR (Augmented Reality) technology, overlapping calculation information into real world. 'Dismantling Data Collection System' is to collect necessary data for improving accuracy of decommissioning planning by evaluating work content and worker equipage, work time for dismantlement works. 'Generated Waste Management system' is a system recording necessary information by attaching the barcode to dismantled wastes or the containers. We can get the information of generated waste by recording generation place, generated time, treatment method and the contents. These subsystems enable to carry out reasonable and safe decommissioning of Fugen. In addition, we expect that those systems will be used for decommissioning of other nuclear facilities in the future. (authors)

Evaluation of decontamination during dismantling of plutonium-contaminated glove boxes

International Nuclear Information System (INIS)

Kinugasa, Manabu; Taguchi, Seigi; Ohzeki, Satoru; Inoue, Yoshiaki; Kashima, Sadamitsu

1981-01-01

The dismantling work of plutonium-contaminated glove boxes was carried out. These glove boxes had been used for the R and D of plutonium-uranium mixed oxide fuel for 15 years. The work was carried out in a pressure-controlled greenhouse, and the contamination of air in the greenhouse was monitored continuously. In order to reduce the contamination of air during dismantling, the decontamination and fixation of loose contaminants on the surfaces of glove boxes were very important. The correlation between decontamination and the contamination of air regarding dismantling is reported in this paper. The surface contamination density of the glove boxes was measured utilizing the smear method before and after the decontamination, and the decontamination effects were estimated. The contamination of air during dismantling was continuously measured with a plutonium dust monitor. It was found that loose contamination exponentially decreased by the decontamination process. When the so-called wet glove boxes, which contained wet recovery and waste disposal apparatus, were dismantled, the contamination of air did not exceed 500 (MPC) a. However, the contamination of air exceeded 500 (MPC) a several times in the present work of dismantling the so-called dry glove boxes which had been used for the fabrication of plutonium-uranium mixed oxide pellets. (Kato, T.)

Method of repairing pressure tube type reactors

International Nuclear Information System (INIS)

Asada, Takashi.

1983-01-01

Purpose: To enable to re-start the reactor operation in a short time, upon occurrence of failures in a pressure tube, as well as directly examine the cause for the failures in the pressure tube. Method: The pressure tube reactor main body comprises a calandria tank of a briquette form, pressure tubes, fuel assemblies and an iron-water shielding body. If failure is resulted to a pressure tube, the reactor operation is at first shutdown and nuclear fuel assemblies are extracted to withdraw from the pressure tube. Then, to an inlet pipe way and an outlet pipeway connected to the failed pressure tube, are attached plugs by means of welding or the like at the appropriate position where the radiation exposure dose is lower and the repairing work can be performed with ease. The pressure tube is disconnected to withdraw from the inlet pipeway and the outlet pipeway and, instead, radiation shielding plug tube is inserted and shield cooling device is actuated if required, wherein the reactor is actuated to re-start the operation. (Yoshino, Y.)

Reactor Safety Commission Code of Practice for Pressurized Water Reactors

International Nuclear Information System (INIS)

1990-01-01

The Reactor Safety Commission of the Federal German Republic has summarized in the form of Official Guidelines the safety requirements which, in the Commission's view, have to be met in the design, construction and operation of a nuclear power station equipped with a pressurized water reactor. The Third Edition of the RSK Guidelines for pressurized water reactors dated 14.10.81. is a revised and expanded version of the Second Edition dated 24.1.79. The Reactor Safety Commission will with effect from October 1981 use these Guidelines in consultations on the siting of and safety concept for the installation approval of future pressurized water reactors and will assess these nuclear power stations during their erection in the light of these Guidelines. They have not however been immediately conceived for the adaptation of existing nuclear power stations, whether under construction or in operation. The scope of application of these Guidelines to such nuclear power stations will have to be examined for each individual case. The main aim of the Guidelines is to simplify the consultation process within the reactor Safety Commission and to provide early advice on the safety requirements considered necessary by the Commission. (author)

Dismantling techniques

Energy Technology Data Exchange (ETDEWEB)

Wiese, E.

1998-03-13

Most of the dismantling techniques used in a Decontamination and Dismantlement (D and D) project are taken from conventional demolition practices. Some modifications to the techniques are made to limit exposure to the workers or to lessen the spread of contamination to the work area. When working on a D and D project, it is best to keep the dismantling techniques and tools as simple as possible. The workers will be more efficient and safer using techniques that are familiar to them. Prior experience with the technique or use of mock-ups is the best way to keep workers safe and to keep the project on schedule.

Dismantling techniques

International Nuclear Information System (INIS)

Wiese, E.

1998-01-01

Most of the dismantling techniques used in a Decontamination and Dismantlement (D and D) project are taken from conventional demolition practices. Some modifications to the techniques are made to limit exposure to the workers or to lessen the spread of contamination to the work area. When working on a D and D project, it is best to keep the dismantling techniques and tools as simple as possible. The workers will be more efficient and safer using techniques that are familiar to them. Prior experience with the technique or use of mock-ups is the best way to keep workers safe and to keep the project on schedule

National School of Dismantling

International Nuclear Information System (INIS)

Ivaldi, Fabienne

2003-01-01

The National Institut of Nuclear Sciences and Techniques founded of 2001 a National School of Dismantling, NSD, at the end, which was validated by CEA, COGEMA, EDF and ANDRA. This school addresses four major issues: Decontamination; Dismantling; Demolition and waste Disposal (4D). Dedicated for instructing scientific and technical knowledge and know-how, needed in dismantling the nuclear installations, NSD has as targets: - personnel at engineering and operational level; - personnel occupied with involved trades from conception through intervention; - students and employees on leave; - employees while training on the job. Initial basic education for students in collaboration with schools and universities concerns: - master degree in radioactive waste management; - master degree in dismantling; - professional license in 3 D; - pro 4 D graduation. NSD is also engaged in continual formation for employees qualified, or not, adapted to the needs generated by the following tasks and personnel: - introduction in dismantling; - project team; - specialist engineer; - team head; - agent for remedial action; - agent for dismantling. The National School of Dismantling joins a network of human and technological capabilities confined within the 4 D frame, namely: - scientific and technical competencies (experts, instructors working in the nuclear field and dismantling); - pedagogical competence (professionals from basic and continual education); - specific material means such as those used by construction site schools, mock-ups, rooms for practical training etc

Reactor pressure vessel status report

International Nuclear Information System (INIS)

Strosnider, J.; Wichman, K.; Elliot, B.

1994-12-01

This report gives a brief description of the reactor pressure vessel (RPV), followed by a discussion of the radiation embrittlement of RPV beltline materials and the two indicators for measuring embrittlement, the end-of-license (EOL) reference temperature and the EOL upper-shelf energy. It also summarizes the GL 92-01 effort and presents, for all 37 boiling water reactor plants and 74 pressurized water reactor plants in the United States, the current status of compliance with regulatory requirements related to ensuring RPV integrity. The staff has evaluated the material data needed to predict neutron embrittlement of the reactor vessel beltline materials. These data will be stored in a computer database entitled the reactor vessel integrity database (RVID). This database will be updated annually to reflect the changes made by the licensees in future submittals and will be used by the NRC staff to assess the issues related to vessel structural integrity

Dismantling technologies trends

International Nuclear Information System (INIS)

Devaux, P.

2009-01-01

In this work dismantling technologies trends realized by the CEA are reviewed. There following technologies are presented: Data acquisition from facilities; Scenario studies; Remote handling and carriers; Dismantling techniques; Decontamination.

Pressure tube reactors

International Nuclear Information System (INIS)

Natori, Hisahide.

1981-01-01

Purpose: To improve the electrical power generation efficiency in a pressure tube reactor in which coolants and moderators are separated by feedwater heating with heat generated in heavy water and by decreasing the amount of steams to be extracted from the turbine. Constitution: A heat exchanger and a heavy water cooler are additionally provided to a conventional pressure tube reactor. The heat exchanger is disposed at the pre-stage of a low pressure feedwater heater series. High temperature heavy water heated in the core is passed through the primary side of the exchanger, while feedwater is passed through the secondary side. The cooler is disposed on the downstream of the heat exchanger in the flowing direction of the heavy water, in which heavy water from the heat exchanger is passed through the primary side and the auxiliary equipment cooling water is sent to the secondary side thereof. Accordingly, since extraction of heating steams is no more necessary, the steam can be used for the rotation of the turbine, and the electrical power generation efficiency can be improved. (Seki, T.)

The decommissioning of the KEMA suspension test reactor

International Nuclear Information System (INIS)

Spruyt, A.; Peters, D.; Loon, W.M.G.M. van; Boekschoten, H.J.C.; Brugman, H.

1991-01-01

In this report the decommissioning of the KEMA Suspension Test Reactor (KSTR) is described. This reactor was a 1 MWth aqueous homo-geneous nuclear reactor in which a suspension of a mixed oxide UO 2 / ThO 2 in light water was circulated in a closed loop through a sphere-shaped core vessel. The reactor, located on KEMA premises, made 150 MW of heat during its critical periods. Dismantling of this reactor, with its many connected subsystems, meant the mastering of activated components which were also contaminated on inner surfaces caused by small fuel deposits (alpha contaminants) and fission products (beta, gamma contaminants). A description is given of the save removal of the fuel, the remote dismantling of systems and components and the disposal of steel scrap and other materials. Important features are the measures to be taken and provisions needed for safe handling, for the reduction of the radiation dose for the working team and the prevention of spreading of activity over the working area and the environment. It has been demonstrated that safe dismantling and disposal of such systems can be achieved. Experience gained at KEMA for the proper dismantling and for safety measures to be taken for workers and the environment can be made available for similar dismantling projects. A cost break-down is included in the report. (author). 22 refs.; 52 figs.; 12 tabs

Pressure tube reactor

International Nuclear Information System (INIS)

Matsumoto, Tomoyuki; Fujino, Michihira.

1980-01-01

Purpose: To equalize heavy water flow distribution by providing a nozzle for externally injecting heavy water from a vibration preventive plate to the upper portion to feed the heavy water in a pressure tube reactor and swallowing up heavy water in a calandria tank to supply the heavy water to the reactor core above the vibration preventive plate. Constitution: A moderator injection nozzle is mounted on the inner wall of a calandria tank. Heavy water is externally injected above the vibration preventive plate, and heavy water in the calandria tank is swallowed up to supply the heavy water to the core reactor above the vibration preventive plate. Therefore, the heavy water flow distribution can be equalized over the entire reactor core, and the distribution of neutron absorber dissolved in the heavy water is equalized. (Yoshihara, H.)

Some regulation aspects in dismantling

International Nuclear Information System (INIS)

Niel, J.C.

1993-01-01

In the French regulation framework, operations linked to dismantling are controlled by an overall technical and legislative system applied to all the different stages of the facility (commissioning, etc.). Government control on facilities under dismantling is aimed at dismantling operation safety and security, and dismantling waste processing in order to ensure public and environmental protection

Development of plasma arc cutting technique for dismantlement of reactor internals in JPDR decommissioning program

International Nuclear Information System (INIS)

Yanagihara, Satoshi; Tanaka, Mitsugu; Ujihara, Norio.

1988-01-01

The decommissioning program for JPDR has been conducted by JAERI since 1981 under contact with the Science and Technology Agency of Japan. The development of cutting tools for dismantling the JPDR is one of the important items in the program. An underwater plasma arc cutting technique was selected for dismantling the JPDR core internals. The study was concentrated on improving the cutting ability in water. Various cutting tests were conducted changing the parameters such as arc current, supply gas and cutting speed to evaluate the most effective cutting condition. Through the study, it has been achieved to be able to cut a 130 mm thick stainless steel plate in water. In addition, the amount and the characteristics of by-products were measured during the cutting tests for the safety evaluation of the dismantling activities. Final cutting tests and checkout of whole plasma arc cutting system were conducted using a mockup water pool and test pieces simulating the JPDR core internals. It was proved from the tests that the cutting system developed in the program will be applicable for the JPDR core internals dismantlement. (author)

Results of reactor pressure vessels ISI

International Nuclear Information System (INIS)

Cepcek, S.

1994-01-01

To find out the possible influence of the annealing process to reactor pressure vessel integrity, a large in-service inspection programme has been implemented as an associated activity to reactor pressure vessel annealing. In this paper the approach to the RPV in-service inspection is shown. Also, the main results and conclusions following in-service inspection are presented. (author). 3 refs, 1 fig

The Grenoble CEA Center: dismantled and rehabilitated

International Nuclear Information System (INIS)

Anon.

2013-01-01

The denuclearization program of the CEA center in Grenoble was launched in 2001. It involves 6 nuclear facilities (3 research reactors: Melusine, Siloette, and Siloe, and 1 laboratory (LAMA) and 2 units for processing wastes). The dismantling works were finished at the end of 2012 and the 2013 program concerns: the demolition of the buildings homing Melusine and Siloe reactors, the final rehabilitation of the Siloe raft, and the final rehabilitation of the laboratory and of the waste processing units. The budget is 117*10 6 euros for Siloe, 28*10 6 euros for Melusine, 6*10 6 euros for Siloette, 70*10 6 euros for the LAMA, and 90*10 6 euros for the 2 waste processing units. (A.C.)

Computerized reactor pressure vessel materials information system

International Nuclear Information System (INIS)

Strosnider, J.; Monserrate, C.; Kenworthy, L.D.; Tether, C.D.

1980-10-01

A computerized information system for storage and retrieval of reactor pressure vessel materials data was established, as part of Task Action Plan A-11, Reactor Vessel Materials Toughness. Data stored in the system are necessary for evaluating the resistance of reactor pressure vessels to flaw-induced fracture. This report includes (1) a description of the information system; (2) guidance on accessing the system; and (3) a user's manual for the system

Recycling of concrete generated from Nuclear Power Plant dismantling

International Nuclear Information System (INIS)

Ogawa, Hideo; Nawa, Toyoharu; Ishikura, Takeshi; Tanaka, Hiroaki

2013-01-01

Reactor decommissioning required various technologies such as dismantling of facilities, decontamination, radioactivity measurement and recycling of dismantling wastes. This article discussed recycling of demolished concrete wastes. Dismantling of reactor building of large one unit of nuclear power plants would generate about 500 K tons of concrete wastes, about 98% of which was non-radioactive and could be used as base course material or backfill material after crushed to specified particle size. Since later part of 1990s, high quality recycled aggregate with specified limit of bone-dry density, water absorptivity and amount of fine aggregate had been developed from demolished concrete with 'Heat and rubbing method', 'Eccentric rotor method' and 'Screw grinding method' so as to separate cements attached to aggregate. Recycled aggregates were made from concrete debris with 'Jaw crusher' to particle size less than 40 mm and then particle size control or grinded by various grinding machines. Recycled fine aggregates made from crushing would have fragile site with cracks, air voids and bubbles. The author proposed quality improvement method to selectively separate fragile defects from recycled aggregates using weak grinding force, leaving attached pastes much and preventing fine particle generation as byproducts. This article outlined experiments to improve quality of recycled fine aggregates and their experimental results confirmed improvement of flow ability and compressive strength of mortal using recycled fine aggregates using 'Particle size selector' and 'Ball mill' so as to remove their fragile parts less than 2%. Mortal made from recycled fine aggregate could also prevent permeation of chloride ion. Recycled aggregate could be used for concrete instead of natural aggregate. (T. Tanaka)

U P1, an example for advanced techniques applied to high level activity dismantling

International Nuclear Information System (INIS)

Michel-Noel, M.; Calixte, O.; Blanchard, S.; Bani, J.; Girones, P.; Moitrier, C.; Terry, G.; Bourdy, R.

2014-01-01

The U P1 plant on the CEA Marcoule site was dedicated to the processing of spend fuels from the G1, G2 and G3 plutonium-producing reactors. This plant represents 20.000 m 2 of workshops housing about 1000 hot cells. In 1998, a huge program for the dismantling and cleaning-up of the UP1 plant was launched. CEA has developed new techniques to face the complexity of the dismantling operations. These techniques include immersive virtual reality, laser cutting, a specific manipulator arm called MAESTRO and remote handling. (A.C.)

State space modeling of reactor core in a pressurized water reactor

Energy Technology Data Exchange (ETDEWEB)

Ashaari, A.; Ahmad, T.; M, Wan Munirah W. [Department of Mathematical Science, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Shamsuddin, Mustaffa [Institute of Ibnu Sina, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Abdullah, M. Adib [Swinburne University of Technology, Faculty of Engineering, Computing and Science, Jalan Simpang Tiga, 93350 Kuching, Sarawak (Malaysia)

2014-07-10

The power control system of a nuclear reactor is the key system that ensures a safe operation for a nuclear power plant. However, a mathematical model of a nuclear power plant is in the form of nonlinear process and time dependent that give very hard to be described. One of the important components of a Pressurized Water Reactor is the Reactor core. The aim of this study is to analyze the performance of power produced from a reactor core using temperature of the moderator as an input. Mathematical representation of the state space model of the reactor core control system is presented and analyzed in this paper. The data and parameters are taken from a real time VVER-type Pressurized Water Reactor and will be verified using Matlab and Simulink. Based on the simulation conducted, the results show that the temperature of the moderator plays an important role in determining the power of reactor core.

Health and Safety Considerations Associated with Sodium-Cooled Experimental Nuclear Fuel Dismantlement

Energy Technology Data Exchange (ETDEWEB)

Carvo, Alan E. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2015-04-01

Between the mid-1970s and the mid-1980s Sandia National Laboratory constructed eleven experimental assemblies to simulate debris beds formed in a sodium-cooled fast breeder reactor. All but one of the assemblies were irradiated. The experimental assemblies were transferred to the Idaho National Laboratory (INL) in 2007 and 2008 for storage, dismantlement, recovery of the uranium for reuse in the nuclear fuel cycle, and disposal of unneeded materials. This paper addresses the effort to dismantle the assemblies down to the primary containment vessel and repackage them for temporary storage until such time as equipment necessary for sodium separation is in place.

Decommissioning and dismantling of nuclear and fuel cycle facilitites in Spain

International Nuclear Information System (INIS)

Gravalos, J.M.; Alamo, S.

1992-01-01

In the recent past, and as a consequence of a fire in the turbine island of the Vandellos I Graphite Gas type Nuclear Plant, which damaged the facility to a point that recovery was not judged economically feasible, the authorities decided on the final shutdown of the plant. Several studies were performed in order to select the dismantling strategy to be adopted. In spite of Valdellos I being the first commercial reactor to be decommissioned in Spain, several research reactors and fuel cycle facilities, which have reached the end of their commercial lives, are at present at different stages of their dismantling and decommissioning process as is described further. The development of an exemption policy for below regulatory concern wastes is considered a very significant issue regarding decommissioning as it has a large impact on radioactive waste volumes, and thus on costs. Aware of this problem ENRESA together with Spanish regulatory authorities are working in close cooperation with CEC research programs to complete the development of criteria and methodologies for the application of exemption practices in Spain

Pressure vessel for nuclear reactor plant consisting of several pre-stressed cast pressure vessels

International Nuclear Information System (INIS)

Bodmann, E.

1984-01-01

Several cylindrical pressure vessel components made of pressure castings are arranged on a sector of a circle around the cylindrical cast pressure vessel for accommodating the helium cooled HTR. Each component pressure vessel is connected to the reactor vessel by a horizontal gas duct. The contact surfaces between reactor and component pressure vessel are in one plane. In the spaces between the individual component pressure vessels, there are supporting blocks made of cast iron, which are hollow and also have flat surfaces. With the reactor vessel and the component pressure vessels they form a disc-shaped connecting part below and above the gas ducts. (orig./PW)

Reactor pressure vessel support

International Nuclear Information System (INIS)

Butti, J.P.

1977-01-01

A link and pin support system provides the primary vertical and lateral support for a nuclear reactor pressure vessel without restricting thermally induced radial and vertical expansion and contraction. (Auth.)

Press kit. EPR (European pressurized water reactor). The advanced nuclear reactor

International Nuclear Information System (INIS)

2004-10-01

Nuclear energy, which provides a steady supply of electricity at low cost, has its rightful place in the energy mix of the 21 century, which puts the emphasis on sustainable development. In this framework, this document presents the advantages of the EPR (European Pressurized water Reactor). The EPR is the only third generation reactor under construction today. It is an evolutionary reactor that represents a new generation of pressurized water reactors with no break in the technology used for the most recent models. The EPR can guarantee a safe, inexpensive electricity supply, without adding to the greenhouse effect. It meets the requirements of the safety authorities and lives up to the expectations of electricity utilities. (A.L.B.)

Stationary low power reactor No. 1 (SL-1) accident site decontamination ampersand dismantlement project

International Nuclear Information System (INIS)

Perry, E.F.

1995-01-01

The Army Reactor Area (ARA) II was constructed in the late 1950s as a test site for the Stationary Low Power Reactor No. 1 (SL-1). The SL-1 was a prototype power and heat source developed for use at remote military bases using a direct cycle, boiling water, natural circulation reactor designed to operate at a thermal power of 3,000 kW. The ARA II compound encompassed 3 acres and was comprised of (a) the SL-1 Reactor Building, (b) eight support facilities, (c) 50,000-gallon raw water storage tank, (d) electrical substation, (e) aboveground 1,400-gallon heating oil tank, (f) underground 1,000-gallon hazardous waste storage tank, and (g) belowground power, sewer, and water systems. The reactor building was a cylindrical, aboveground facility, 39 ft in diameter and 48 ft high. The lower portion of the building contained the reactor pressure vessel surrounded by gravel shielding. Above the pressure vessel, in the center portion of the building, was a turbine generator and plant support equipment. The upper section of the building contained an air cooled condenser and its circulation fan. The major support facilities included a 2,500 ft 2 two story, cinder block administrative building; two 4,000 ft 2 single story, steel frame office buildings; a 850 ft 2 steel framed, metal sided PL condenser building, and a 550 ft 2 steel framed decontamination and laydown building

Pressurized water reactor with a reactor pressure vessel

International Nuclear Information System (INIS)

Werres, L.

1979-01-01

The core barrel is suspended from a flange by means of a grid. The coolant enters the barrel from below through the grid. In order to get a uniform flow over the reactor core there is provided for a guiding device below the grid. It consists of a cylindrical shell with borings uniformly distributed around the shell as well as fins on the inner surface of the shell and slots at the bottom facing the pressure vessel. (GL) [de

Sampling of Reactor Pressure Vessel and Core Internals

International Nuclear Information System (INIS)

Oberhaeuser, R.

2011-01-01

Decommissioning and dismantling of nuclear power plants is a growing business, as a huge number of plants built in the 1970s have now reached their lifetime. It is well known that dismantling a nuclear power plant means an extraordinary expense for the owner respectively operator. Besides the dismantling works, the disposal of activated components and other nuclear waste is very expensive. Moreover, the fact that, in most countries, final disposal facilities are not available yet implies the need for interim storage on-site in specially built facilities. It can be concluded that a special attention is paid on producing a minimal radioactive waste volume. For this, optimized dismantling and packaging concepts have to be developed. The challenge is a fair balance between the obtainment of optimized packing and on the other side the fulfillment of stringent regulations set by the authorities and the storage requirements. The basis of a well-founded, optimized dismantling and packaging concept must always be the detailed knowledge of the radiological condition of the component to be dismantled. In the best case a 3- dimensional activation model contributes to this basis.

Towards a more professional demolition and dismantling industry

International Nuclear Information System (INIS)

1988-01-01

The work of the National Economic Development Office Demolition and Dismantling Group in four areas which are crucial to the economic performance of the demolition and dismantling industry and its safety record is considered. The first concerns the availability and accessibility of information about unconventional structures and details are given of the sort of information often kept for different types of structure. Secondly, the need is stressed for guidelines for the client, particularly on the risks involved and the choice of a competent contractor. Thirdly, basic credentials which it is important for contractors to set out in order to establish a good reputation for the industry are set out. Finally, the particular case of nuclear power station decommissioning is considered with reference to the size of the market, the pioneering knowledge to be gained from the decommissioning of the Windscale Advanced Gas-cooled Reactor, private sector involvement and the special techniques required. (U.K.)

Pressurized water reactor flow arrangement

International Nuclear Information System (INIS)

Gibbons, J.F.; Knapp, R.W.

1980-01-01

A flow path is provided for cooling the control rods of a pressurized water reactor. According to this scheme, a small amount of cooling water enters the control rod guide tubes from the top and passes downwards through the tubes before rejoining the main coolant flow and passing through the reactor core. (LL)

Pressurized water reactor systems

International Nuclear Information System (INIS)

Meyer, P.J.

1975-01-01

Design and mode of operation of the main PWR components are described: reactor core, pressure vessel and internals, cooling systems with pumps and steam generators, ancillary systems, and waste processing. (TK) [de

French activities on gas cooled reactors

International Nuclear Information System (INIS)

Bastien, D.

1996-01-01

The gas cooled reactor programme in France originally consisted of eight Natural Uranium Graphite Gas Cooled Reactors (UNGG). These eight units, which are now permanently shutdown, represented a combined net electrical power of 2,375 MW and a total operational history of 163 years. Studies related to these reactors concern monitoring and dismantling of decommissioned facilities, including the development of methods for dismantling. France has been monitoring the development of HTRs throughout the world since 1979, when it halted its own HTR R and D programme. France actively participates in three CRPs set up by the IAEA. (author). 1 tab

Pressurized water reactor inspection procedures

International Nuclear Information System (INIS)

Heinrich, D.; Mueller, G.; Otte, H.J.; Roth, W.

1998-01-01

Inspections of the reactor pressure vessels of pressurized water reactors (PWR) so far used to be carried out with different central mast manipulators. For technical reasons, parallel inspections of two manipulators alongside work on the refueling cavity, so as to reduce the time spent on the critical path in a revision outage, are not possible. Efforts made to minimize the inspection time required with one manipulator have been successful, but their effects are limited. Major reductions in inspection time can be achieved only if inspections are run with two manipulators in parallel. The decentralized manipulator built by GEC Alsthom Energie and so far emmployed in boiling water reactors in the USA, Spain, Switzerland and Japan allows two systems to be used in parallel, thus reducing the time required for standard inspection of a pressure vessel from some six days to three days. These savings of approximately three days are made possible without any compromises in terms of positioning by rail-bound systems. During inspection, the reactor refueling cavity is available for other revision work without any restrictions. The manipulator can be used equally well for inspecting standard PWR, PWR with a thermal shield, for inspecting the land between in-core instrumentation nozzles, BWR with and without jet pumps (complementary inspection), and for inspecting core support shrouds. (orig.) [de

Reactor decommissioning strategy: a new start for BNFL

International Nuclear Information System (INIS)

Woollam, P.; Nurden, P.

2001-01-01

The key points of BNFL Magnox Electric's revised waste management and reactor decommissioning strategy for the reactor sites are enlisted. Reactors will be defuelled as soon as practicable after shutdown. Predominantly Caesium contaminated plant will be dismantled when it is no longer needed. Cobalt contaminated plant such as boilers will remain in position until the reactors are dismantled, but appropriate decontamination technology will be regularly reviewed. All buildings except the reactor buildings will be dismantled as soon as practicable after they are no longer needed. Operational ILW, except some activated components, will be retrieved and packaged during the Care and Maintenance preparation period. All wastes will be stored on site, and handled in the long term in accordance with Government policy. Reactor buildings and their residual contents will be placed in a passive safe storage Care and Maintenance condition in a manner appropriate for the site. Contaminated land will be managed to maintain public safety. The reactors will be finally dismantled in a sequenced programme with a start date and duration to be decided at the appropriate time in the light of circumstances prevalent at that time. Currently, the Company is considering a sequenced programme across all sites, notionally beginning around 100 years from station shutdown, leading to a range of deferral periods. For provisioning purposes, the Company has costed a strategy involving reactor dismantling deferrals ranging from 85 to about 105 years in order to demonstrate prudent provisioning to meet its liabilities. A risk provision to reflect the potential for shorter deferral periods is included in the cost estimates. The end point for reactor decommissioning is site clearance and delicensing, based on the assumption that a reasonably practicable interpretation of the 'no danger' clause in the Nuclear Installations Act 1965 (as amended) can be developed. In line with Government policy, and taking

Leak detector for reactor pressure vessel

International Nuclear Information System (INIS)

Morimoto, Mikio.

1991-01-01

A branched pipe is disposed to a leak off pipeline led from a flange surface which connects the main body and the upper lid of a reactor pressure vessel. An exhaust pump is disposed to the branched pipe and a moisture gage is disposed on the side of the exhaustion and a dry air supplier is connected to the branched pipe. Upon conducting a pressure-proof leak test for the reactor pressure vessel, the exhaust pump is operated and an electromagnet valve disposed at the upstream of the dry air supplier is opened and closed repeatedly. The humidity of air sucked by the exhaust pump is detected by the moisture gage. If leaks should be caused in the joining surface of the flange, leaked water is diffused as steams. Accordingly, occurrence of leak can be detected instantly based on the comparison with the moisture level of the dry air as a standard. In this way, a leak test can be conducted reliably in a short period of time with no change of for the reactor pressure container itself. (I.N.)

N Reactor pressure tube 2566 postirradiation examination

International Nuclear Information System (INIS)

Scott, K.V.

1978-01-01

Pressure tube 2566 was removed from N Reactor in July, 1977 to initiate the postirradiation examination program required by the Technical Specifications. Destructive examination of the pressure tube, after a maximum accumulated fluence of 4.6 x 10 21 n/cm 2 (E > 1 MeV), was conducted at the Hanford Engineering Development Laboratory to determine the effects of reactor service on the mechanical properties and hydrogen absorption and corrosion characteristics of the pressure tube. Tube 2566 is the sixth tube removed for destructive examination since the initial reactor startup. Evaluation of test results reveal that no significant detrimental changes have occurred in the parameters studied, since the last tube was removed in 1974

Experience acquired by EDF in implementation of its dismantling programme

Energy Technology Data Exchange (ETDEWEB)

Klaeyle, S.; Dalmas, R.; Davoust, M. [EDF - Centre d' Ingenerie Deconstruction Environnement (CIDEN), 69 - Villeurbanne (France)

2008-07-01

EDF decided in 2001 to implement immediate dismantling of its first generation nuclear plants. Seven years after this decision, the physical progress of the programme is 24% and is due to reach 50 % by 2013. This paper presents the experiences acquired in the fields of organization, project and programme management, purchasing strategies and waste management. Until now, the principal works involve Brennilis (Heavy water), ChoozA (PWR) and Creys Malville (fast breeder reactor). The detailed pre-project concerning the first of the six gas graphite reactors is complete and the call for bids process has been launched. The organization to manage projects, established at the De-construction and Environment Engineering Center (CIDEN), is effective and productive. Estimates of costs and expenses are coherent, which makes the forecasts put together to finance the programme secure. CIDEN has carried out significant engineering work over the last six years, making it possible to apply for the administrative authorizations which have now been obtained or are in the process of being obtained. Technical specifications are prepared at an optimized level of detail according to a contractual policy adapted to the complexity of the operations and the sharing of risk with manufacturers. The ChoozA contractualization process has been launched and the first dismantling work has begun in the nuclear auxiliary part. The main Brennilis contract will be completed in mid- 2008 and dismantling works will restart after renewal of the decree which was cancelled in mid-2007. Treatment of sodium from Creys Malville is about to begin, leading to elimination of the sodium risk by 2013. The very low activity waste (TFA) and low to medium activity waste (FA-MA) removal chains are operational. The intermediate activity/long lived (MA-VL) waste will be stored in a facility which will be brought into operational service in 2012. The graphite storage center is due to open between 2017 and 2019

Ultrasound periodic inspections of reactor pressure vessels

International Nuclear Information System (INIS)

Haniger, L.

1980-01-01

Two versions are described of ultrasonic equipment for periodic inspections of reactor pressure vessels. One uses the principle of exchangeable programmators with solid-state logic while the other uses programmable logic with semiconductor memories. The equipment is to be used for inspections of welded joints on the upper part of the V-1 reactor pressure vessel. (L.O.)

Decommissioning of the Salaspils Research Reactor

Directory of Open Access Journals (Sweden)

Abramenkovs Andris

2011-01-01

Full Text Available In May 1995, the Latvian government decided to shut down the Salaspils Research Reactor and to dispense with nuclear energy in the future. The reactor has been out of operation since July 1998. A conceptual study on the decommissioning of the Salaspils Research Reactor was drawn up by Noell-KRC-Energie- und Umwelttechnik GmbH in 1998-1999. On October 26th, 1999, the Latvian government decided to start the direct dismantling to “green-field” in 2001. The upgrading of the decommissioning and dismantling plan was carried out from 2003-2004, resulting in a change of the primary goal of decommissioning. Collecting and conditioning of “historical” radioactive wastes from different storages outside and inside the reactor hall became the primary goal. All radioactive materials (more than 96 tons were conditioned for disposal in concrete containers at the radioactive wastes depository “Radons” at the Baldone site. Protective and radiation measurement equipment of the personnel was upgraded significantly. All non-radioactive equipment and materials outside the reactor buildings were released for clearance and dismantled for reuse or conventional disposal. Contaminated materials from the reactor hall were collected and removed for clearance measurements on a weekly basis.

N Reactor pressure tube 1350 postirradiation examination

International Nuclear Information System (INIS)

Cook, D.J.

1977-01-01

The N Reactor pressure tubes were fabricated from Zircaloy-2 primarily due to the excellent corrosion resistance, low neutron absorption, and high strength properties of this alloy. Irradiation damage mechanisms increase the strength and decrease the ductility of the Zircaloy-2. Irradiation data available at the time the tubes were installed indicated that fast neutron irradiation damage mechanisms would not decrease the ductility to unacceptable levels over the estimated plant life of 25 to 30 years. However, because the tubes are a primary coolant system component and only limited data are available on irradiation effects at high fluences, a Postirradiation Examination (PIE) program was developed to assure that service factors do not compromise pressure tube integrity essential to reactor safety. The PIE program requires that a pressure tube be periodically removed from the reactor for destructive testing. The N Reactor Technical Specifications specify that the frequency of pressure tube removal and examination be based upon the previous PIE test results. Four pressure tubes were examined before tube 1350, and the test results were summarized in individual reports. PIE results on tube 1350 were summarized along with the test results on the previous four tubes in a previous report. The purpose of this report is to present in detail the results on PIE of pressure tube 1350, and, in particular, document the technique by which the fracture toughness of the pressure tube was determined

LEP dismantling starts

CERN Multimedia

2000-01-01

Since the end of November, various teams have been getting stuck into dismantling the LEP accelerator and its four experiments. After making the installations safe, the dismantling and removal of 40,000 tonnes of equipment is underway. Down in the tunnel, it is a solemn moment. It is 10 o'clock on 13 December and Daniel Regin, one of those heading the dismantling work, moves in on a magnet, armed with a hydraulic machine. Surrounded by teams gathered there for a course in dismantling, he makes the first cut into LEP. The great deconstruction has begun. In little over than a year, the accelerator will have been cleared away to make room for its successor, the LHC. The start of the operation goes back to 27 November. Because before setting about the machine with hydraulic shears and monkey wrenches, LEP had first to be made safe - it was important to make sure the machine could be taken apart without risk. All the SPS beam injection systems to LEP were cut off. The fluids used for cooling the magnets and superc...

Reactor Pressure Vessel (RPV) Acquisition Strategy

Energy Technology Data Exchange (ETDEWEB)

Mizia, Ronald Eugene [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2008-04-01

The Department of Energy has selected the High Temperature Gas-cooled Reactor design for the Next Generation Nuclear Plant (NGNP) Project. The NGNP will demonstrate the use of nuclear power for electricity and hydrogen production. It will have an outlet gas temperature in the range of 900°C and a plant design service life of 60 years. The reactor design will be a graphite moderated, helium-cooled, prismatic or pebble-bed reactor and use low-enriched uranium, TRISO-coated fuel. The plant size, reactor thermal power, and core configuration will ensure passive decay heat removal without fuel damage or radioactive material releases during accidents. The NGNP Materials Research and Development (R&D) Program is responsible for performing R&D on likely NGNP materials in support of the NGNP design, licensing, and construction activities. Selection of the technology and design configuration for the NGNP must consider both the cost and risk profiles to ensure that the demonstration plant establishes a sound foundation for future commercial deployments. The NGNP challenge is to achieve a significant advancement in nuclear technology while at the same time setting the stage for an economically viable deployment of the new technology in the commercial sector soon after 2020. The purpose of this report is to address the acquisition strategy for the NGNP Reactor Pressure Vessel (RPV). This component will be larger than any nuclear reactor pressure vessel presently in service in the United States. The RPV will be taller, larger in diameter, thicker walled, heavier and most likely fabricated at the Idaho National Laboratory (INL) site of multiple subcomponent pieces. The pressure vessel steel can either be a conventional materials already used in the nuclear industry such as listed within ASME A508/A533 specifications or it will be fabricated from newer pressure vessel materials never before used for a nuclear reactor in the US. Each of these characteristics will present a

Cleanup and Dismantling of Highly Contaminated Ventilation Systems Using Robotic Tools - 13162

International Nuclear Information System (INIS)

Chambon, Frederic; CIZEL, Jean-Pierre; Blanchard, Samuel

2013-01-01

The UP1 plant reprocessed nearly 20,000 tons of used natural uranium gas cooled reactor fuel coming from the first generation of civil nuclear reactors in France. Following operating incidents in the eighties, the ventilation system of the continuous dissolution line facility was shut down and replaced. Two types of remote controlled tool carriers were developed to perform the decontamination and dismantling operations of the highly contaminated ventilation duct network. The first one, a dedicated small robot, was designed from scratch to retrieve a thick powder deposit within a duct. The robot, managed and confined by two dedicated glove boxes, was equipped for intervention inside the ventilation duct and used for carrying various cleanup and inspection tools. The second type, consisting of robotic tools developed on the base of an industrial platform, was used for the clean-up and dismantling of the ventilation duct system. Depending on the type of work to be performed, on the shape constraints of the rooms and any equipment to be dismantled, different kinds of robotic tools were developed and installed on a Brokk 40 carrier. After more than ten years of ventilation duct D and D operations at the UP1 plant, a lot of experience was acquired about remote operations. The three main important lessons learned in terms of remote controlled operation are: characterizing the initial conditions as much as reasonably possible, performing non-radioactive full scale testing and making it as simple and modular as possible. (authors)

Cleanup and Dismantling of Highly Contaminated Ventilation Systems Using Robotic Tools - 13162

Energy Technology Data Exchange (ETDEWEB)

Chambon, Frederic [AREVA FEDERAL SERVICES, Columbia MD (United States); CIZEL, Jean-Pierre [AREVA BE/NV, Marcoule (France); Blanchard, Samuel [CEA DEN/DPAD, Marcoule (France)

2013-07-01

The UP1 plant reprocessed nearly 20,000 tons of used natural uranium gas cooled reactor fuel coming from the first generation of civil nuclear reactors in France. Following operating incidents in the eighties, the ventilation system of the continuous dissolution line facility was shut down and replaced. Two types of remote controlled tool carriers were developed to perform the decontamination and dismantling operations of the highly contaminated ventilation duct network. The first one, a dedicated small robot, was designed from scratch to retrieve a thick powder deposit within a duct. The robot, managed and confined by two dedicated glove boxes, was equipped for intervention inside the ventilation duct and used for carrying various cleanup and inspection tools. The second type, consisting of robotic tools developed on the base of an industrial platform, was used for the clean-up and dismantling of the ventilation duct system. Depending on the type of work to be performed, on the shape constraints of the rooms and any equipment to be dismantled, different kinds of robotic tools were developed and installed on a Brokk 40 carrier. After more than ten years of ventilation duct D and D operations at the UP1 plant, a lot of experience was acquired about remote operations. The three main important lessons learned in terms of remote controlled operation are: characterizing the initial conditions as much as reasonably possible, performing non-radioactive full scale testing and making it as simple and modular as possible. (authors)

Dismantling and decommissioning of Jose Cabrera nuclear power plant

International Nuclear Information System (INIS)

Rodriguez, A.

2009-01-01

With the start of the dismantling works at the Jose Cabrera nuclear power plant now in sight, this is an appropriate moment to look back and consider recent history. The first time that the issue of nuclear power plant dismantling was dealt with was in 1975, at a conference in Paris entitled Nuclear Energy Maturity. Up until then the entire question had been one of design, construction and operation, but since that moment and it has been quite a while since that conference dismantling has begun to be seen as just another activity in the nuclear cycle, a final activity that will sooner or later affect all the facilities, an activity different from its predecessors and with the ultimate objective of restoring the sites for whatever use might be determined. During the 1960s and 1970s, the construction of nuclear power plants was widespread across the entire world. It was the baby boom of nuclear energy and now, forty or fifty years later, we are seeing the arrival of the end of the service lifetime of these plants and are faced with the corresponding general process of dismantling these installations. The dismantling of nuclear power plants has ceased to be an emerging issue and is now consolidated as a regular activity in the nuclear industry, albeit an activity that lacks adequate financing or specific regulation in certain countries. Fortunately this is not the case in Spain, since economic provisions have been planned and the regulatory framework developed. In view of the above, the dismantling of the nuclear power plants is an industrial activity involving specific technologies that implies new professional and business opportunities that should be absorbed and seized by society. In Spain the path followed in this direction has been a long one, as is underlined by the experiences of dismantling the Argos (Barcelona, 1998- 2004) and Arbi (Bilbao, 2002-2005) research reactors, the Andujar Uranium Mill (Jaen, 1991-1995), the Vandellos I nuclear power plant

Evolution of radiation protection of overall decommissioning and Dismantling of a Nuclear Power Plants

International Nuclear Information System (INIS)

Ortiz, M. T.; Ondaro, M.; Irun, I.; Just, J.

2000-01-01

From the point of view of Radiological Protection, the overall Decommissioning and Dismantling (D and D) Plan of a Nuclear Power Plant cannot be considered in isolation without considering the evolution of the radiological characteristics of the installation and the site itself from previous, during and final states. This experience of D and D is the first in Spain and in other European countries due to several aspects: 1) the reference reactor technology, 2) total grass power, and 3) management of a great amount of materials to be released. Three decommissioning alternatives were studied: Indefinite maintenance in shutdown state, Stage 1. Stage 2 for the defuelled reactor vessel and contents, with decontamination of most of the rest of the site. Immediate dismantling to Stage 3. Stage 2 was the alternative selected with the release of 80% of the site, keeping the remaining 20% of the site as a regulated area, housing the reactor vessel in a new structure and removing the radioactive waste. The above, along with the fact that this is a specific type of natural uranium-graphite-gas plant (NUGG) and that ownership of the facility has been transferred for dismantling (from HIFRENSA to ENRESA), implies a series of preliminary considerations that, for the purposes of this article, are compiled in the following aspects: a) Preliminary phase prior to transfer, b) Preparatory phase, and c) Dismantling phase. This paper describes aspects under the D and D experiences at CN-V1 NPP, now in progress, from the point of view of the radiological aspects in relation with the continuous updating of the source term. Operative Radiological nuclide vectors, applicable in the Radiation Protection tasks, are also commented to prevent and evaluate several risks during the execution of the works. Finally, there is a description of the results obtained from the work performed to decay the three actual nuclide vectors, to evaluate and obtain activity calculations for the release of the

Integrity of the reactor coolant boundary of the European pressurized water reactor (EPR)

Energy Technology Data Exchange (ETDEWEB)

Goetsch, D.; Bieniussa, K.; Schulz, H.; Jalouneix, J.

1997-04-01

This paper is an abstract of the work performed in the frame of the development of the IPSN/GRS approach in view of the EPR conceptual safety features. EPR is a pressurized water reactor which will be based on the experience gained by utilities and designers in France and in Germany. The reactor coolant boundary of a PWR includes the reactor pressure vessel (RPV), those parts of the steam generators (SGs) which contain primary coolant, the pressurizer (PSR), the reactor coolant pumps (RCPs), the main coolant lines (MCLs) with their branches as well as the other connecting pipes and all branching pipes including the second isolation valves. The present work covering the integrity of the reactor coolant boundary is mainly restricted to the integrity of the main coolant lines (MCLs) and reflects the design requirements for the main components of the reactor coolant boundary. In the following the conceptual aspects, i.e. design, manufacture, construction and operation, will be assessed. A main aspect is the definition of break postulates regarding overall safety implications.

Integrity of the reactor coolant boundary of the European pressurized water reactor (EPR)

International Nuclear Information System (INIS)

Goetsch, D.; Bieniussa, K.; Schulz, H.; Jalouneix, J.

1997-01-01

This paper is an abstract of the work performed in the frame of the development of the IPSN/GRS approach in view of the EPR conceptual safety features. EPR is a pressurized water reactor which will be based on the experience gained by utilities and designers in France and in Germany. The reactor coolant boundary of a PWR includes the reactor pressure vessel (RPV), those parts of the steam generators (SGs) which contain primary coolant, the pressurizer (PSR), the reactor coolant pumps (RCPs), the main coolant lines (MCLs) with their branches as well as the other connecting pipes and all branching pipes including the second isolation valves. The present work covering the integrity of the reactor coolant boundary is mainly restricted to the integrity of the main coolant lines (MCLs) and reflects the design requirements for the main components of the reactor coolant boundary. In the following the conceptual aspects, i.e. design, manufacture, construction and operation, will be assessed. A main aspect is the definition of break postulates regarding overall safety implications

Pressurized Water Reactors (PWR) and Boiling Water Reactors (BWR) are compared

International Nuclear Information System (INIS)

Greneche, D.

2014-01-01

This article compares the 2 types of light water reactors that are used to produce electricity: the Pressurized Water Reactor (PWR) and the Boiling Water Reactor (BWR). Historically the BWR concept was developed after the PWR concept. Today 80% of light water reactors operating in the world are of PWR-type. This comparison is comprehensive and detailed. First the main technical features are reviewed and compared: reactor architecture, core and fuel design, reactivity control, reactor vessel, cooling systems and reactor containment. Secondly, various aspects concerning reactor operations like reactor control, fuel management, maintenance, inspections, radiation protection, waste generation and reactor reliability are presented and compared for both reactors. As for the issue of safety, it is highlighted that the accidental situations are too different for the 2 reactors to be compared. The main features of reactor safety are explained for both reactors

Reactor Structural Materials: Reactor Pressure Vessel Steels

International Nuclear Information System (INIS)

Chaouadi, R.

2000-01-01

The objectives of SCK-CEN's R and D programme on Rector Pressure Vessel (RPV) Steels are:(1) to complete the fracture toughness data bank of various reactor pressure vessel steels by using precracked Charpy specimens that were tested statically as well as dynamically; (2) to implement the enhanced surveillance approach in a user-friendly software; (3) to improve the existing reconstitution technology by reducing the input energy (short cycle welding) and modifying the stud geometry. Progress and achievements in 1999 are reported

Analysis of removal alternatives for the Heavy Water Components Test Reactor at the Savannah River Site. Revision 1

Energy Technology Data Exchange (ETDEWEB)

Owen, M.B.

1997-04-01

This engineering study evaluates different alternatives for decontamination and decommissioning of the Heavy Water Components Test Reactor (HWCTR). Cooled and moderated with pressurized heavy water, this uranium-fueled nuclear reactor was designed to test fuel assemblies for heavy water power reactors. It was operated for this purpose from march of 1962 until December of 1964. Four alternatives studied in detail include: (1) dismantlement, in which all radioactive and hazardous contaminants would be removed, the containment dome dismantled and the property restored to a condition similar to its original preconstruction state; (2) partial dismantlement and interim safe storage, where radioactive equipment except for the reactor vessel and steam generators would be removed, along with hazardous materials, and the building sealed with remote monitoring equipment in place to permit limited inspections at five-year intervals; (3) conversion for beneficial reuse, in which most radioactive equipment and hazardous materials would be removed and the containment building converted to another use such as a storage facility for radioactive materials, and (4) entombment, which involves removing hazardous materials, filling the below-ground structure with concrete, removing the containment dome and pouring a concrete cap on the tomb. Also considered was safe storage, but this approach, which has, in effect, been followed for the past 30 years, did not warrant detailed evaluation. The four other alternatives were evaluate, taking into account factors such as potential effects on the environment, risks, effectiveness, ease of implementation and cost. The preferred alternative was determined to be dismantlement. This approach is recommended because it ranks highest in the comparative analysis, would serve as the best prototype for the site reactor decommissioning program and would be most compatible with site property reuse plans for the future.

Analysis of removal alternatives for the Heavy Water Components Test Reactor at the Savannah River Site. Revision 1

International Nuclear Information System (INIS)

Owen, M.B.

1997-04-01

This engineering study evaluates different alternatives for decontamination and decommissioning of the Heavy Water Components Test Reactor (HWCTR). Cooled and moderated with pressurized heavy water, this uranium-fueled nuclear reactor was designed to test fuel assemblies for heavy water power reactors. It was operated for this purpose from march of 1962 until December of 1964. Four alternatives studied in detail include: (1) dismantlement, in which all radioactive and hazardous contaminants would be removed, the containment dome dismantled and the property restored to a condition similar to its original preconstruction state; (2) partial dismantlement and interim safe storage, where radioactive equipment except for the reactor vessel and steam generators would be removed, along with hazardous materials, and the building sealed with remote monitoring equipment in place to permit limited inspections at five-year intervals; (3) conversion for beneficial reuse, in which most radioactive equipment and hazardous materials would be removed and the containment building converted to another use such as a storage facility for radioactive materials, and (4) entombment, which involves removing hazardous materials, filling the below-ground structure with concrete, removing the containment dome and pouring a concrete cap on the tomb. Also considered was safe storage, but this approach, which has, in effect, been followed for the past 30 years, did not warrant detailed evaluation. The four other alternatives were evaluate, taking into account factors such as potential effects on the environment, risks, effectiveness, ease of implementation and cost. The preferred alternative was determined to be dismantlement. This approach is recommended because it ranks highest in the comparative analysis, would serve as the best prototype for the site reactor decommissioning program and would be most compatible with site property reuse plans for the future

Decommissioning activities for Salaspils research reactor - 59055

International Nuclear Information System (INIS)

Abramenkovs, A.; Malnacs, J.

2012-01-01

In May 1995, the Latvian government decided to shut down the Salaspils Research Reactor (SRR). The reactor is out of operation since July 1998. A conceptual study for the decommissioning of SRR has been carried out by Noell-KRC-Energie- und Umwelttechnik GmbH at 1998-1999. The Latvian government decided to start the direct dismantling to 'green field' in October 26, 1999. The upgrade of decommissioning and dismantling plan was performed in 2003-2004 years, which change the main goal of decommissioning to the 'brown field'. The paper deals with the SRR decommissioning experience during 1999-2010. The main decommissioning stages are discussed including spent fuel and radioactive wastes management. The legal aspects and procedures for decommissioning of SRR are described in the paper. It was found, that the involvement of stakeholders at the early stages significantly promotes the decommissioning of nuclear facility. Radioactive waste management's main efforts were devoted to collecting and conditioning of 'historical' radioactive wastes from different storages outside and inside of reactor hall. All radioactive materials (more than 96 tons) were conditioned in concrete containers for disposal in the radioactive wastes repository 'Radons' at Baldone site. The dismantling of contaminated and activated components of SRR systems is discussed in paper. The cementation of dismantled radioactive wastes in concrete containers is discussed. Infrastructure of SRR, including personal protective and radiation measurement equipment, for decommissioning purposes was upgraded significantly. Additional attention was devoted to the free release measurement's technique. The certified laboratory was installed for supporting of all decommissioning activities. All non-radioactive equipments and materials outside of reactor buildings were released for clearance and dismantled for reusing or conventional disposing. Weakly contaminated materials from reactor hall were collected

Decontamination of the HFR dismantling cell

International Nuclear Information System (INIS)

Cloes, K.; Husmann, K.; Hardt, P. von der.

1976-05-01

The Commission of the European Communities operates in the Petten Establishment of the Joint Research Centre (EURATOM), a 45 MW light-water cooled materials testing reactor, the HFR. Inside the reactor containment building, on top of a side wing of the main pool, a hot cell had been constructed for the dismantling, of irradiated equipment, and brought into active service in July 1966. Early in 1973, the cell was contaminated by 0.1 to 1 Ci of Po 210 , originating from an irradiation capsule containing Bi impregnated graphite specimens. Due to the elevated radiotoxicity of this isotope, and to numerous potential ways of spreading out the contamination it was decided to stop routine operation of the cell until a satisfactory degree of decontamination had been reached. Two years have been spent for preparation of specialized equipment and thorough clean-up and overhaul work of the cell. It went back into normal operation on February 21st, 1975 and has since then been working very successfully

Fuel assembly for pressure loss variable PWR type reactor

International Nuclear Information System (INIS)

Yoshikuni, Masaaki.

1993-01-01

In a PWR type reactor, a pressure loss control plate is attached detachably to a securing screw holes on the lower surface of a lower nozzle to reduce a water channel cross section and increase a pressure loss. If a fuel assembly attached with the pressure loss control plate is disposed at a periphery of the reactor core where the power is low and heat removal causes no significant problem, a flowrate at the periphery of the reactor core is reduced. Since this flowrate is utilized for removal of heat from fuel assemblies of high powder at the center of the reactor core where a pressure loss control plate is not attached, a thermal limit margin of the whole reactor core is increased. Thus, a limit of power peaking can be moderated, to obtain a fuel loading pattern improved with neutron economy. (N.H.)

Supercritical-pressure light water cooled reactors

CERN Document Server

Oka, Yoshiaki

2014-01-01

This book focuses on the latest reactor concepts, single pass core and experimental findings in thermal hydraulics, materials, corrosion, and water chemistry. It highlights research on supercritical-pressure light water cooled reactors (SCWRs), one of the Generation IV reactors that are studied around the world. This book includes cladding material development and experimental findings on heat transfer, corrosion and water chemistry. The work presented here will help readers to understand the fundamental elements of reactor design and analysis methods, thermal hydraulics, materials and water

Dismantling of a furnace and gloveboxes of a U3O8 with 20% enrichment production line

International Nuclear Information System (INIS)

Yorio, Daniel; Cinat, Enrique; Cincotta, Daniel; Fernandez, Carlos A.; Bruno, Hernan R.; Camacho, Esteban F.; Boero, Norma

1999-01-01

In the Uranium Powder Manufacturing Plant at CAC, U 3 O 8 with 20% enrichment is manufactured for fuel plates to be used in test reactors. This plant is in full operation since 1986, producing uranium oxide for Peru, Algeria, Iran, Egypt and the RA-3-CAE reactors. Some of the equipment of the Plant have finished their life time and one of the furnaces of the processing line had to be replaced. This work implied the dismantling not only of the furnace, but also of the gloveboxes connected to the furnace and the dismantling of the extraction lines and air injection of the gloveboxes. The work had to be performed with the necessary care in order to minimize risks and effects on personnel, installations and environment involved. (author)

Decommissioning of the MZFR nuclear power plant at the Karlsruhe Nuclear Research Center

International Nuclear Information System (INIS)

Demant, W.; Engelhardt, G.

1991-01-01

The MZFR multipurpose research reactor was permanently shut down on May 3, 1984. The envisaged decommissioning concept provides for disposal in five steps. The first two steps are devoted to preparatory work on dismantling and simplification of the systems needed for dismantling. In the third step the reactor auxiliary systems in the auxiliary building and in the fourth step the reactor systems in the reactor building will be dismantled. In the fifth step remote dismantling of the reactor pressure vessel and demolition of the building will take place. The scheduled date of completion is the year 2001. (author)

Prestressed concrete pressure vessels for nuclear reactors - 1973

Energy Technology Data Exchange (ETDEWEB)

1977-01-01

This standard deals with the design, construction, inspection and testing of prestressed concrete pressure vessels for nuclear reactors. Such pressure vessels serve the dual purpose of shielding and containing gas cooled nuclear reactors and are a form of civil engineering structure requiring particularly high integrity, and ensured leak tightness. (Metric)

Analysis of aging mechanism and management for HTR-PM reactor pressure vessel

International Nuclear Information System (INIS)

Sun Yunxue; Shao Jin

2015-01-01

Reactor pressure vessel is an important part of the reactor pressure boundary, its important degree ranks high in ageing management and life assessment of nuclear power plant. Carrying out systematic aging management to ensure reactor pressure vessel keeping enough safety margins and executing design functions is one of the key factors to guarantee security and stability operation for nuclear power plant during the whole lifetime and prolong life. This paper briefly introduces the structure and aging mechanism of reactor pressure vessel in pressurized water reactor nuclear power plant, and introduces the design principle and structure characteristics of HTR-PM. At the same time, this paper carries out preliminary analysis and exploration. and discusses aging management of HTR-PM reactor pressure vessel. Finally, the advice of carring out aging management for HTR-PM reactor pressure vessel is proposed. (authors)

SCW Pressure-Channel Nuclear Reactor Some Design Features

Science.gov (United States)

Pioro, Igor L.; Khan, Mosin; Hopps, Victory; Jacobs, Chris; Patkunam, Ruban; Gopaul, Sandeep; Bakan, Kurtulus

Concepts of nuclear reactors cooled with water at supercritical pressures were studied as early as the 1950s and 1960s in the USA and Russia. After a 30-year break, the idea of developing nuclear reactors cooled with SuperCritical Water (SCW) became attractive again as the ultimate development path for water cooling. The main objectives of using SCW in nuclear reactors are: 1) to increase the thermal efficiency of modern Nuclear Power Plants (NPPs) from 30-35% to about 45-48%, and 2) to decrease capital and operational costs and hence decrease electrical energy costs (˜1000 US/kW or even less). SCW NPPs will have much higher operating parameters compared to modern NPPs (pressure about 25 MPa and outlet temperature up to 625°C), and a simplified flow circuit, in which steam generators, steam dryers, steam separators, etc., can be eliminated. Also, higher SCW temperatures allow direct thermo-chemical production of hydrogen at low cost, due to increased reaction rates. Pressure-tube or pressure-channel SCW nuclear reactor concepts are being developed in Canada and Russia for some time. Some design features of the Canadian concept related to fuel channels are discussed in this paper. The main conclusion is that the development of SCW pressure-tube nuclear reactors is feasible and significant benefits can be expected over other thermal-energy systems.

A methodology to simulate the cutting process for a nuclear dismantling simulation based on a digital manufacturing platform

International Nuclear Information System (INIS)

Hyun, Dongjun; Kim, Ikjune; Lee, Jonghwan; Kim, Geun-Ho; Jeong, Kwan-Seong; Choi, Byung Seon; Moon, Jeikwon

2017-01-01

Highlights: • Goal is to provide existing tech. with cutting function handling dismantling process. • Proposed tech. can handle various cutting situations in the dismantlement activities. • Proposed tech. can be implemented in existing graphical process simulation software. • Simulation results have demonstrated that the proposed technology achieves its goal. • Proposed tech. enlarges application of graphic simulation into dismantlement activity. - Abstract: This study proposes a methodology to simulate the cutting process in a digital manufacturing platform for the flexible planning of nuclear facility decommissioning. During the planning phase of decommissioning, visualization and verification using process simulation can be powerful tools for the flexible planning of the dismantling process of highly radioactive, large and complex nuclear facilities. However, existing research and commercial solutions are not sufficient for such a situation because complete segmented digital models for the dismantling objects such as the reactor vessel, internal assembly, and closure head must be prepared before the process simulation. The preparation work has significantly impeded the broad application of process simulation due to the complexity and workload. The methodology of process simulation proposed in this paper can flexibly handle various dismantling processes including repetitive object cuttings over heavy and complex structures using a digital manufacturing platform. The proposed methodology, which is applied to dismantling scenarios of a Korean nuclear power plant in this paper, is expected to reduce the complexity and workload of nuclear dismantling simulations.

EPR (European Pressurized Reactor)

International Nuclear Information System (INIS)

2015-01-01

This document presents the EPR (European Pressurized Reactor), a modernised version of PWRs which uses nuclear fission. It indicates to which category it belongs (third generation). It briefly describes its operation: recalls on nuclear fission, electricity production in a nuclear reactor. It presents and comments its characteristics: power, thermal efficiency, redundant systems for safety control, double protective enclosure, expected lifetime, use of MOX fuel, modular design. It discusses economic stakes (expected higher nuclear electricity competitiveness, but high construction costs), and safety challenges (design characteristics, critics by nuclear safety authorities about the safety data processing system). It presents the main involved actors (Areva, EDF) and competitors in the field of advanced reactors (Rosatom with its VVER 1200, General Electric with its ABWR and its ESBWR, Mitsubishi with its APWR, Westinghouse with its AP100) while outlining the importance of certifications and delays to obtain them. After having evoked key data on EPR fuel consumption, it indicates reactors under construction, evokes potential markets and perspectives

Radiation embrittlement of Spanish nuclear reactor pressure vessel steels

International Nuclear Information System (INIS)

Bros, J.; Ballesteros, A.; Lopez, A.

1993-01-01

Commercial pressurized water reactor (PWR) and boiling water reactor (BWR) nuclear power plants contain a series of pressure vessel steel surveillance capsules as the principal means of monitoring radiation effects on the pressure vessel. Changes in fracture toughness are more severe in surveillance capsules than in reactor vessel materials because of their proximity of the reactor core. Therefore, it is possible to predict changes in fracture toughness of the reactor vessel materials. This paper describes the status of the reactor vessel surveillance program relating to Spanish nuclear power plants. To date, twelve capsules have been removed and analyzed from seven of the nine Spanish reactors in operation. The results obtained from the analysis of these capsules are compared with the predictions of the Nuclear Regulatory Commission (NRC) Regulatory Guide 1.99, Rev. 2, by means of measured and expected increase of the nil-ductility transition reference temperature (RT NDT ). The comparison is made considering the different variables normally included in the studies of radiation response of reactor pressure vessel materials, such as copper content of steel, level of neutron fluence above 1 MeV, base metal or weld metal, and so forth. The surveillance data have been used for determining the adjusted reference temperatures and upper shelf energies at any time. The results have shown that the seven pressure vessels are in excellent condition to continue operating with safety against brittle fracture beyond the design life, without the need to recuperate the degraded properties of the materials by annealing of the vessel

Standard Technical Specifications for Westinghouse pressurized water reactors

International Nuclear Information System (INIS)

Virgilio, M.J.

1980-09-01

The Standard Technical Specifications for Westinghouse Pressurized Water Reactors (W-STS) is a generic document prepared by the U.S. NRC for use in the licensing process of current Westinghouse Pressurized Water Reactors. The W-STS sets forth the Limits, Operating Conditions and other requirements applicable to nuclear reactor facility operation as set forth in by Section 50.36 of 10 CFR Part 50 for the protection of the health and safety of the public. This document is revised periodically to reflect current licensing requirements

Real-time reactor coolant system pressure/temperature limit system

International Nuclear Information System (INIS)

Newton, D.G.; Schemmel, R.R.; Van Scooter, W.E. Jr.

1991-01-01

This patent describes an system, used in controlling the operating of a nuclear reactor coolant system, which automatically calculates and displays allowable reactor coolant system pressure/temperature limits within the nuclear reactor coolant system based upon real-time inputs. It comprises: means for producing signals representative of real-time operating parameters of the nuclear reactor cooling system; means for developing pressure and temperature limits relating the real-time operating parameters of the nuclear reactor coolant system, for normal and emergency operation thereof; means for processing the signals representative of real-time operating parameters of the nuclear reactor coolant system to perform calculations of a best estimate of signals, check manual inputs against permissible valves and test data acquisition hardware for validity and over/under range; and means for comparing the representative signals with limits for the real-time operating parameters to produce a signal for a real-time display of the pressure and temperature limits and of the real-time operating parameters use an operator in controlling the operation of the nuclear reactor coolant system

Pressurizer pump reliability analysis high flux isotope reactor

International Nuclear Information System (INIS)

Merryman, L.; Christie, B.

1993-01-01

During a prolonged outage from November 1986 to May 1990, numerous changes were made at the High Flux Isotope Reactor (HFIR). Some of these changes involved the pressurizer pumps. An analysis was performed to calculate the impact of these changes on the pressurizer system availability. The analysis showed that the availability of the pressurizer system dropped from essentially 100% to approximately 96%. The primary reason for the decrease in availability comes because off-site power grid disturbances sometimes result in a reactor trip with the present pressurizer pump configuration. Changes are being made to the present pressurizer pump configuration to regain some of the lost availability

The dismantling of nuclear installations: The dismantling of nuclear installations at the CEA's Directorate for nuclear energy; The CEA's sanitation and dismantling works: example of one of the Marcoule UP1 program lots; Research and innovation in sanitation-dismantling; Global optimisation of the management of dismantling radioactive wastes

International Nuclear Information System (INIS)

Hauet, Jean-Pierre; Piketty, Laurence; Moitrier, Cyril; Blanchard, Samuel; Soulabaille, Yves; Georges, Christine; Dutzer, Michel; Legee, Frederic

2016-01-01

This publication proposes a set of four articles which addresses issues related to the dismantling of nuclear installations in France, notably for the different involved actors such as the CEA and the ANDRA. The authors more particularly address the issue and the general strategy of dismantling within the Directorate for nuclear energy of the CEA; comment the example of one of the Marcoule UP1 program lots to highlight sanitation and dismantling works performed by the CEA; discuss current research and innovation activities within the CEA regarding sanitation and dismantling; and comment how to globally optimise the management of radioactive wastes produced by dismantling activities

Visualization of a dismantling environment for an evaluation of a worker's dose during the decommissioning of KRR-1 and 2

International Nuclear Information System (INIS)

Park, Hee Seong; Kim, Sung Kyun; Lee, Kune Woo; Jung, Chong Hun; Jin, Seong Il

2008-01-01

The purpose of this paper is to provide a basis for an optimization of a dismantling process of a research reactor and nuclear facility. An optimization of a dismantling process should be at the beginning of a study for an evaluation of the radioactivity inventory and the safety of the workers. Many countries have conducted an optimization to achieve a shortened dismantling schedule, a reduction of the amount of waste, and cut down on the decommissioning by using computer graphics such as animation, simulation, and virtual reality. In the present study, we propose methods for identifying the existence of radioactivity which is contained in the dismantled objects and for evaluating a worker's dose through a simulation. To evaluate a worker's external dose under a virtual dismantling environment generated by computer graphics, the shape of the thermal column horizontal door was created by 3D CAD and the radiation dose surrounding the door was calculated by using MCNP-4C. An animation that can demonstrate a dismantling procedure according to a dismantling scenario was produced. For matching the radiation dose, which was calculated by MCNP-4C with an area where workers are dismantling a door, a simulation module was developed which could show a worker's external dose in real-time. The result from the distribution of the radioactivity enables us to specify where the most contaminated part of the dismantling objects is. In the animation, a virtual worker demonstrated a dismantling activity procedure as a chosen scenario. In the simulation, a worker's exposure dose rate in real-time has been evaluated

Fracture risk assessment for the pressurized water reactor pressure vessel under pressurized thermal shock events

International Nuclear Information System (INIS)

Chou, Hsoung-Wei; Huang, Chin-Cheng

2016-01-01

Highlight: • The PTS loading conditions consistent with the USNRC's new PTS rule are applied as the loading condition for a Taiwan domestic PWR. • The state-of-the-art PFM technique is employed to analyze a reactor pressure vessel. • Novel flaw model and embrittlement correlation are considered in the study. • The RT-based regression formula of NUREG-1874 was also utilized to evaluate the failure risks of RPV. • For slightly embrittled RPV, the SO-1 type PTSs play more important role than other types of PTS. - Abstract: The fracture risk of the pressurized water reactor pressure vessel of a Taiwan domestic nuclear power plant has been evaluated according to the technical basis of the U.S.NRC's new pressurized thermal shock (PTS) screening criteria. The ORNL's FAVOR code and the PNNL's flaw models were employed to perform the probabilistic fracture mechanics analysis associated with plant specific parameters of the domestic reactor pressure vessel. Meanwhile, the PTS thermal hydraulic and probabilistic risk assessment data analyzed from a similar nuclear power plant in the United States for establishing the new PTS rule were applied as the loading conditions. Besides, an RT-based regression formula derived by the U.S.NRC was also utilized to verify the through-wall cracking frequencies. It is found that the through-wall cracking of the analyzed reactor pressure vessel only occurs during the PTS events resulted from the stuck-open primary safety relief valves that later reclose, but with only an insignificant failure risk. The results indicate that the Taiwan domestic PWR pressure vessel has sufficient structural margin for the PTS attack until either the current license expiration dates or during the proposed extended operation periods.

The dismantling of nuclear installations in the Grenoble CEA centre - Press book 2013

International Nuclear Information System (INIS)

Laveissiere, Stephane; Coronini, Vincent

2013-01-01

After having outlined the importance of the project for the Grenoble CEA centre, this document presents the objectives, issues and challenges of dismantling activities performed on various nuclear installations located in the CEA centre of Grenoble. Objectives are presented in terms of agenda, predicted production of radioactive wastes, budget, personnel and steering committee. The various nuclear installations are presented: experimental reactors (Melusine, Siloe, Siloette), LAMA (laboratory of analysis of active materials), STED (station for the treatment of effluents and wastes). The safety and protection of workers is addressed in terms of protection and monitoring measures, and of exposure to radiations. The next part deals with the monitoring of the environment (actors, history of control of the centre's releases, control points, releases, atmosphere monitoring, and hydrological monitoring). A second part presents the global strategy of the CEA for its activities of sanitation and nuclear dismantling: present operations, dismantling activities in Fontenay-aux-Roses and in Marcoule, economic organization, contribution of advanced technology in radiological measurement and control, simulation and modelling, decontamination techniques, cutting operations, and remotely controlled operations

The dismantling of CEA nuclear installations

International Nuclear Information System (INIS)

Piketty, Laurence

2016-03-01

After having indicated locations of French nuclear installations which are currently being dismantled (about 30 installations), and recalled the different categories of radioactive wastes with respect to their activity level and the associated storage options, this article gives an overview of various aspects of dismantling, more precisely in the case of installations owned and managed by the CEA. These operations comprise the dismantling itself, the recovery and packaging of wastes, old effluents and spent fuels. The organisation and responsible departments within the CEA are presented, and the author outlines some operational problematic issues met due to the age of installations (traceability of activities, regulation evolutions). The issue of financing is then discussed, and its uncertainties are outlined. The dismantling strategy within the CEA-DEN is described, with reference to legal and regulatory frameworks. The next parts of the article address the organisation and the economic impact of these decontamination and dismantling activities within the CEA-DEN, highlight how R and D and advanced technology are a support to this activities as R and D actions address all scientific and technical fields of nuclear decontamination and dismantling. An overview of three important dismantling works is proposed: Fontenay-aux-Roses, the Marcoule CEA centre (a reference centre in the field of nuclear dismantling and decontamination) and the Grenoble CEA centre (reconversion in R and D activities in the fields of technologies of information, of communication, technologies, for health, and in renewable energies). The last part addresses the participation to the Strategic Committee of the Nuclear Sector (CSFN)

Thermal annealing of an embrittled reactor pressure vessel

International Nuclear Information System (INIS)

Mager, T.R.; Dragunov, Y.G.; Leitz, C.

1998-01-01

As a result of the popularity of the Agencies report 'Neutron Irradiation Embrittlement of Reactor Pressure Vessel Steels' of 1975, it was decided that another report on this broad subject would be of use. In this report, background and contemporary views on specially identified areas of the subject are considered as self-contained chapters, written by experts. Chapter 11 deals with thermal annealing of an embrittled reactor pressure vessel. Anneal procedures for vessels from both the US and the former USSR are mentioned schematically, wet anneals at lower temperature and dry anneals above RPV design temperatures are investigated. It is shown that heat treatment is a means of recovering mechanical properties which were degraded by neutron radiation exposure, thus assuring reactor pressure vessel compliance with regulatory requirements

Limit regulation system for pressurized water nuclear reactors

International Nuclear Information System (INIS)

Aleite, W.; Bock, H.W.

1976-01-01

Described is a limit regulation system for a pressurized water nuclear reactor in combination with a steam generating system connected to a turbine, the nuclear reactor having control rods as well as an operational regulation system and a protective system, which includes reactor power limiting means operatively associated with the control rods for positioning the same and having response values between operating ranges of the operational regulation system, on the one hand, and response values of the protective system, on the other hand, and a live steam-minimal pressure regulation system cooperating with the reactor power limiting means and operatively connected to a steam inlet valve to the turbine for controlling the same

The AIDA-MOX 1 program: Results of the French-Russian study on peaceful use of plutonium from dismantled Russian Nuclear weapons

International Nuclear Information System (INIS)

Yegorov, N.N.; Kudriavtsev, E.; Poplavsky, V.; Polyakov, A.; Ouin, X.; Camarcat, N.; Sicard, B.; Bernard, H.

1997-01-01

The Intergovernmental Agreement signed on November 12, 1992, between the governments of France and the Russian Federation instituted cooperation between the two countries for the safe elimination of the excess Russian nuclear weapons. France has allocated 400 million francs to this program, covering transportation and dismantling of nuclear weapons, interim storage and subsequent commercial use of the nuclear materials from the dismantled weapons, nuclear materials accountancy and safeguards, and scientific research. The concept of loading commercial Russian reactors with fuel fabricated from the plutonium recovered from dismantled nuclear weapons of the former Soviet Union is gaining widespread acceptance, and is at the heart of the French-Russian AIDA/MOX project

Project WAGR: The UK demonstration project for power reactor decommissioning - removing the core and looking to completion

International Nuclear Information System (INIS)

Benest, T. G.

2003-01-01

The United Kingdom Atomic Energy Authority (UKAEA) has built and operated a wide range of nuclear facilities since the late 1940's. UKAEA's present mission is to restore the environment of these facilities in a safe and environmentally responsible manner. This restoration includes the decommissioning of a number of redundant research and power reactors, one of which is the Windscale Advanced Gas-cooled Reactor (WAGR). Following shut down, UKAEA decided to continue the prototype function of the reactor into the decommissioning phase to develop dismantling techniques and establish waste routes. The reactor core and pressure vessel are now being dismantled in a programme of 10 campaigns, seven of which have been completed since 1998. It is anticipated that the current programme will be completed by summer 2005. This paper outlines the history of the reactor, the operation of the waste-processing route, the installed dismantling equipment and the successful completion of the first seven campaigns. This earlier work has been described in a number of publications and conferences, so this paper concentrates on recent work to select and develop cutting equipment to dismantle the core support structures and the pressure vessel. The decommissioning of the Windscale Advance Gas-cooled reactor is being undertaken to demonstrate that a power reactor can be decommissioned shortly after shutdown. The removal of the core and pressure vessel has been broken down into a series of 10 campaigns associated with particular core components. The first 7 campaigns have been successfully completed and the 8., is expected to commence in September 2003 17 months earlier than planned. Dismantling methodologies and tools have been developed specifically for each of these campaigns. Full-scale mock-ups have been used to test the tools, train the operators and assess the duration of operations. However, despite successful trials, operational experience has shown that some of these tools have not

Nuclear reactors built, being built, or planned: 1987

International Nuclear Information System (INIS)

1988-06-01

Nuclear Reactors Built, Being Built, or Planned contains unclassified information about facilities built, being built, or planned in the United States for domestic use or export as of December 31, 1987. The Office of Scientific and Technical Information, US Department of Energy, gathers this information annually for Washington headquarters and field offices of DOE; from the US Nuclear regulatory Commission; from the US reactor manufacturers who are the principal nuclear contractors for foreign reactor locations; from US and foreign embassies; and from foreign governmental nuclear departments. The major change in this revision involves the data related to shutdown and dismantled facilities. Because this information serves substantially different purposes, it has been accumulated in a separate section, ''Reactors and Facilities Shutdown or Dismantled.'' Cancelled reactors or reactors whose progress has been terminated at some stage before operation are included in this section

Stability analysis of supercritical-pressure light water-cooled reactor in constant pressure operation

International Nuclear Information System (INIS)

Suhwan, JI; Shirahama, H.; Koshizuka, S.; Oka, Y.

2001-01-01

The purpose of this study is to evaluate the thermal-hydraulic and the thermal-nuclear coupled stabilities of a supercritical pressure light water-cooled reactor. A stability analysis code at supercritical pressure is developed. Using this code, stabilities of full and partial-power reactor operating at supercritical pressure are investigated by the frequency-domain analysis. Two types of SCRs are analyzed; a supercritical light water reactor (SCLWR) and a supercritical water-cooled fast reactor (SCFR). The same stability criteria as Boiling Water Reactor are applied. The thermal-hydraulic stability of SCLWR and SCFR satisfies the criteria with a reasonable orifice loss coefficient. The decay ratio of the thermal-nuclear coupled stability in SCFR is almost zero because of a small coolant density coefficient of the fast reactor. The evaluated decay ratio of the thermal-nuclear coupled stability is 3,41 ∼ 10 -V at 100% power in SCFR and 0,028 at 100% power in SCLWR. The sensitivity is investigated. It is found that the thermal-hydraulic stability is sensitive to the mass flow rate strongly and the thermal-nuclear coupled stability to the coolant density coefficient. The bottom power peak distribution makes the thermal-nuclear stability worse and the thermal-nuclear stability better. (author)

Decommissioning and dismantling of nuclear research facilities in Switzerland: lessons learned

International Nuclear Information System (INIS)

Leibundgut, Fritz

2017-01-01

Paul Scherrer Institute is the largest research institute for natural and engineering science in Switzerland. It operated various nuclear facilities from 1960 to 2011: Research reactors DIORIT, SAPHIR and PROTEUS, and an incineration plant for low and medium level radioactive waste. Concerning SAPHIR research reactor: in operation from 1958 to 1993, planning of decommissioning from 1998 to 2000. Decommissioning work started in 2004. Finishing is planned for 2019. Concerning DIORIT research reactor: operation as DIORIT I (20 MWth) from 1960 to 1967, then reconstruction to DIORIT II (30 MWth) and operation from 1970 until 1977. Planning of decommissioning from 1992 to 1994. Decommissioning work started in 1994 and was finished in 2012. Concerning PROTEUS research reactor: in operation from 1966 to 2011. Planning of decommissioning from 2013 to 2014. Starting of decommissioning work is planned for 2017, finishing is planned for the end of 2018 Incineration plant: In operation from 1974 to 2002. Planning of decommissioning from 2011 to 2012. Starting of decommissioning work in 2016. Finishing planned for end of 2019. Treatment of various material categories from dismantling: Concerning aluminum: because of the production of H_2 during solidification in concrete, it was necessary to minimize the surface area. When dismantling research reactors, the aluminum removed was melted in an induction furnace and poured into a 4.5 m"3 concrete container to solidify. Cutting the metal and handling it was largely accomplished remote control, using conventional technology. Concerning Steel/Cast-iron: the storage containers to be filled determined the method used for reducing the size of these materials, and the technique used for handling them. The goal was to optimize the packing density to reduce repository costs. The selected method of reducing the size of components is to cut them up using diamond-tipped tools, like saw blades. Concerning Graphite: for graphite, grinding was the

CFD simulation analysis and validation for CPR1000 pressurized water reactor

International Nuclear Information System (INIS)

Zhang Mingqian; Ran Xiaobing; Liu Yanwu; Yu Xiaolei; Zhu Mingli

2013-01-01

Background: With the rapid growth in the non-nuclear area for industrial use of Computational fluid dynamics (CFD) which has been accompanied by dramatically enhanced computing power, the application of CFD methods to problems relating to Nuclear Reactor Safety (NRS) is rapidly accelerating. Existing research data have shown that CFD methods could predict accurately the pressure field and the flow repartition in reactor lower plenum. But simulations for the full domain of the reactor have not been reported so far. Purpose: The aim is to determine the capabilities of the codes to model accurately the physical phenomena which occur in the full reactor vessel. Methods: The flow field of the CPR1000 reactor which is associated with a typical pressurized water reactor (PWR) is simulated by using ANSYS CFX. The pressure loss in reactor pressure vessel, the hydraulic loads of guide tubes and support columns, and the bypass flow of head dome were obtained by calculations for the full domain of the reactor. The results were validated by comparing with the determined reference value of the operating nuclear plant (LingAo nuclear plant), and the transient simulation was conducted in order to better understand the flow in reactor pressure vessel. Results: It was shown that the predicted pressure loss with CFD code was slightly different with the determined value (10% relative deviation for the total pressure loss), the hydraulic loads were less than the determined value with maximum relative deviation 50%, and bypass flow of head dome was approximately the same with determined value. Conclusion: This analysis practice predicts accurately the physical phenomena which occur in the full reactor vessel, and can be taken as a guidance for the nuclear plant design development and improve our understanding of reactor flow phenomena. (authors)

The nuclear reactor strategy between fast breeder reactors and advanced pressurized water reactors

International Nuclear Information System (INIS)

Seifritz, W.

1983-01-01

A nuclear reactor strategy between fast breeder reactors (FBRs) and advanced pressurized water reactors (APWRs) is being studied. The principal idea of this strategy is that the discharged plutonium from light water reactors (LWRs) provides the inventories of the FBRs and the high-converter APWRs, whereby the LWRs are installed according to the derivative of a logistical S curve. Special emphasis is given to the dynamics of reaching an asymptotic symbiosis between FBRs and APWRs. The main conclusion is that if a symbiotic APWR-FBR family with an asymptotic total power level in the terawatt range is to exist in about half a century from now, we need a large number of FBRs already in an early phase

Aging considerations for PWR [pressurized water reactor] control rod drive mechanisms and reactor internals

International Nuclear Information System (INIS)

Ware, A.G.

1988-01-01

This paper describes age-related degradation mechanisms affecting life extension of pressurized water reactor control rod drive mechanisms and reactor internals. The major sources of age-related degradation for control rod drive mechanisms are thermal transients such as plant heatups and cooldowns, latchings and unlatchings, long-term aging effects on electrical insulation, and the high temperature corrosive environment. Flow induced loads, the high-temperature corrosive environment, radiation exposure, and high tensile stresses in bolts all contribute to aging related degradation of reactor internals. Another problem has been wear and fretting of instrument guide tubes. The paper also discusses age-related failures that have occurred to date in pressurized water reactors

When reactors reach old age

International Nuclear Information System (INIS)

Fischetti, M.

1986-01-01

While the battle over whether to build new nuclear plants has quieted in recent times, a second struggle is shaping up in the United States as reactors approach a new stage of life: retirement. Four decades into the nuclear power age, questions of how best to dismantle and dispose of a nuclear power plant remain largely unanswered. The debates have been mainly academic until now - although reactors have operated for 25 years, decommissioning retired reactors has simply not been fully planned in this country. But the Shippingport Atomic Power Station in Pennsylvania, the first large-scale power reactor to be retired, is now being decommissioned. The work has rekindled the debates in the light of reality. Outside the United States, decommissioning is also being confronted on a new plane. Virtually all groups involved in decommissioning a reactor in the United States - the utility, the Nuclear Regulatory Commission, the U.S. Department of Energy, the U.S. Environmental Protection Agency, state public service commissions, and citizen organizations - agree that for the most part the technology to dismantle and dispose of a reactor safely is available. They disagree, however, on which technical option is the safest or cheapest and on who should pay for dismantlement. And there are further complications: Which regulations must be complied with. How much radiation exposure for workers and the public is acceptable. Even with answers to these questions, uncertainty about where to dispose of the radioactive waste and about how much residual radiation can be left at a former reactor site plagues the architects of decommissioning. This article discusses these questions

Thorough Chemical Decontamination with the MEDOC Process : Batch Treatment of Dismantled Pieces or Loop Treatment of Large Components Such as the BR3 Steam Generator and Pressurizer

International Nuclear Information System (INIS)

Ponnet, M.; Klein, M.; Massaut, V.; Davain, H.; Aleton, G.

2003-01-01

The dismantling of the BR3-PWR reactor leads to the production of large masses of contaminated metallic pieces, including structural materials, primary pipings, tanks and heat exchangers. One of our main objectives is to demonstrate that we can minimize the volume of radioactive waste in an economical way, by the use of alternative waste routes, such as the clearance of materials after thorough decontamination. The SCKoCEN uses its own developed chemical decontamination process, so-called MEDOC (Metal Decontamination by Oxidation with Cerium), based on the use of cerium IV as strong oxidant in sulphuric acid with continuous regeneration using ozone. An industrial installation has been designed and constructed in close collaboration with Framatome-ANP (France). This installation started operation in September 1999 for the treatment of the metallic pieces arising from the dismantling of the BR3 reactor. Since then, more than 25 tons of contaminated material including primary pipes have been treated batchwise with success. 75 % of material could be directly cleared after treatment (Activity lower than 0.1 Bq/g for 60Co) and the other 25% free released after melting activity. The SCKoCEN performed in April 2002 the closed loop decontamination of the BR3 Steam Generator by connection of the MEDOC plant after few adaptations. The decontamination was done within 30 cycles in 3 weeks with consecutive steps like decontamination steps (injection of the solution into the SG) and regeneration steps with ozone. In total, 60 hours of decontamination at 70 C and 130 hours of regeneration were needed to reach the objectives. The tube bundle (600 m2) was attacked and about 10 (micro)m representing more than 41 kg of stainless steel and 2.06 GBq of 60Co was dissolved into the solution. The residual contamination measurements made directly into the water box are still going on, however it seems that the objective to reach the free release criteria after melting is achieved. The next

Experience in the decontamination and dismantling of alpha facilities

International Nuclear Information System (INIS)

Charamathieu, A.

1988-01-01

Experience in dismantling alpha-containing radiochemical installations in France is described. The dismantling programme undertaken by the Societe des Techniques en Milieu Ionisant since 1977 is tabulated. This includes the dismantling of CALCIO and FLUO (plutonium metal), the dismantling of a slag processing plant, the dismantling of part of a medium activity plutonium mine and the dismantling of rooms 82-100 at Marcoule, France. (author)

Windscale advanced gas-cooled reactor (WAGR) decommissioning project overview

International Nuclear Information System (INIS)

Pattinson, A.

2003-01-01

The current BNFL reactor decommissioning projects are presented. The projects concern power reactor sites at Berkely, Trawsfynydd, Hunterstone, Bradwell, Hinkley Point; UKAEA Windscale Pile 1; Research reactors within UK Scottish Universities at East Kilbride and ICI (both complete); WAGR. The BNFL environmental role include contract management; effective dismantling strategy development; implementation and operation; sentencing, encapsulation and transportation of waste. In addition for the own sites it includes strategy development; baseline decommissioning planning; site management and regulator interface. The project objectives for the Windscale Advanced Gas-Cooled Reactor (WAGR) are 1) Safe and efficient decommissioning; 2) Building of good relationships with customer; 3) Completion of reactor decommissioning in 2005. The completed WAGR decommissioning campaigns are: Operational Waste; Hot Box; Loop Tubes; Neutron Shield; Graphite Core and Restrain System; Thermal Shield. The current campaign is Lower Structures and the remaining are: Pressure vessel and Insulation; Thermal Columns and Outer Vault Membrane. An overview of each campaign is presented

Technical challenges for dismantlement verification

International Nuclear Information System (INIS)

Olinger, C.T.; Stanbro, W.D.; Johnston, R.G.; Nakhleh, C.W.; Dreicer, J.S.

1997-01-01

In preparation for future nuclear arms reduction treaties, including any potential successor treaties to START I and II, the authors have been examining possible methods for bilateral warhead dismantlement verification. Warhead dismantlement verification raises significant challenges in the political, legal, and technical arenas. This discussion will focus on the technical issues raised by warhead arms controls. Technical complications arise from several sources. These will be discussed under the headings of warhead authentication, chain-of-custody, dismantlement verification, non-nuclear component tracking, component monitoring, and irreversibility. The authors will discuss possible technical options to address these challenges as applied to a generic dismantlement and disposition process, in the process identifying limitations and vulnerabilities. They expect that these considerations will play a large role in any future arms reduction effort and, therefore, should be addressed in a timely fashion

Pressure suppression facility for reactor container

International Nuclear Information System (INIS)

Fujii, Tadashi; Fukui, Toru; Kataoka, Yoshiyuki; Tominaga, Kenji.

1993-01-01

In a nuclear reactor comprising heat transfer surfaces from a pressure suppression pool at the inside to the outer circumferential pool at the outside, a means for supplying water from a water supply source at the outside of the container to the pools is disposed. Then, a heat transfer means is disposed between the pressure suppression chamber and the water cooling pool. The water supply means comprises a pressurization means for applying pressure to water of the water supply source and a water supply channel. Water is supplied into the pressure suppression pool and the outer circumferential pool to elevate the water level and extend the region of heat contact with the water cooling heat transfer means. In addition, since dynamic pressure is applied to the feedwater, for example, by pressurizing the water surface of the water supply source, water can be supplied without using dynamic equipments such as pumps. Then, since water-cooling heat transfer surface can be extended after occurrence of accident, enlargement of a reactor container and worsening of earthquake proofness can be avoided as much as possible, to improve function for suppressing the pressure in the container. Further, since water-cooling heat transfer region can be extended, the arrangement of the water source and the place to which water is supplied is made optional without considering the relative height therebetween, to improve earthquake proofness. (N.H.)

Functional systems of a pressurized water reactor

International Nuclear Information System (INIS)

Heinzel, V.

1982-01-01

The main topics, discussed in the present paper, are: - Principle design of the reactor coolant system - reactor pressure vessel with internals - containment design - residual heat removal and emergency cooling systems - nuclear component cooling systems - emergency feed water systems - plant electric power supply system. (orig./RW)

Pressurized water reactors: the EPR project

International Nuclear Information System (INIS)

Py, J.P.; Yvon, M.

2007-01-01

EPR (originally 'European pressurized water reactor', and now 'evolutionary power reactor') is a model of reactor initially jointly developed by French and German engineers which fulfills the particular safety specifications of both countries but also the European utility requirements jointly elaborated by the main European power companies under the initiative of Electricite de France (EdF). Today, two EPR-based reactors are under development: one is under construction in Finland and the other, Flamanville 3 (France), received its creation permit decree on April 10, 2007. This article presents, first, the main objectives of the EPR, and then, describes the Flamanville 3 reactor: reactor type and general conditions, core and conditions of operation, primary and secondary circuits with their components, main auxiliary and recovery systems, man-machine interface and instrumentation and control system, confinement and serious accidents, arrangement of buildings. (J.S.)

Heat insulation device for reactor pressure vessel in water

International Nuclear Information System (INIS)

Nakamura, Heiichiro; Tanaka, Yoshimi.

1993-01-01

Outer walls of a reactor pressure vessel are covered with water-tight walls made of metals. A heat insulation metal material is disposed between them. The water tight walls are joined by welding and flanges. A supply pipeline for filling gases and a discharge pipeline are in communication with the inside of the water tight walls. Further, a water detector is disposed in the midway of the gas discharge pipeline. With such a constitution, the following advantages can be attained. (1) Heat transfer from the reactor pressure vessel to water of a reactor container can be suppressed by filled gases and heat insulation metal material. (2) Since the pressure at the inside of the water tight walls can be equalized with the pressure of the inside of the reactor container, the thickness of the water-tight walls can be reduced. (3) Since intrusion of water to the inside of the walls due to rupture of the water tight walls is detected by the water detector, reactor scram can be conducted rapidly. (4) The sealing property of the flange joint portion is sufficient and detaching operation thereof is easy. (I.S.)

Excess-pressure suppression device in a reactor container

International Nuclear Information System (INIS)

Nishio, Masahide

1985-01-01

Purpose: To reliably decrease the radioactivity of radioactive gases when they are released externally. Constitution: The exit of a gas exhaust pipe for discharging gases in a reactor container, on generation of an excess pressure in the reactor container upon loss of coolant accident, is adapted to be always fluided in the cooling tank. Then, the exhaust gases discharged in the cooling tank is realeased to the atmosphere. In this way, the excess pressure in the reactor container can be prevented previously and the radioactivity of the gases released externally is significantly reduced by the scrubbing effect. (Kamimura, M.)

The future 700 MWe pressurized heavy water reactor

International Nuclear Information System (INIS)

Bhardwaj, S.A.

2006-01-01

The design of a 700 MWe pressurized heavy water reactor has been developed. The design is based on the twin 540 MWe reactors at Tarapur of which the first unit has been made critical in less than 5 years from construction commencement. In the 700 MWe design boiling of the coolant, to a limited extent, has been allowed near the channel exit. While making the plant layout more compact, emphasis has been on constructability. Saving in capital cost of about 15%, over the present units, is expected. The paper describes salient design features of 700 MWe pressurized heavy water reactor

Integrity of Magnox reactor steel pressure vessels

International Nuclear Information System (INIS)

Flewitt, P.E.J.; Williams, G.H.; Wright, M.B.

1992-01-01

The background to the safety assessment of the steel reactor pressure vessels for Magnox power stations is reviewed. The evolved philosophy adopted for the 1991 safety cases prepared for the continued operation of four Magnox power stations operated by Nuclear Electric plc is described, together with different aspects of the multi-legged integrity argument. The main revisions to the materials mechanical property data are addressed together with the assessment methodology adopted and their implications for the overall integrity argument formulated for the continued safe operation of these reactor pressure vessels. (author)

Power reactor pressure vessel benchmarks

International Nuclear Information System (INIS)

Rahn, F.J.

1978-01-01

A review is given of the current status of experimental and calculational benchmarks for use in understanding the radiation embrittlement effects in the pressure vessels of operating light water power reactors. The requirements of such benchmarks for application to pressure vessel dosimetry are stated. Recent developments in active and passive neutron detectors sensitive in the ranges of importance to embrittlement studies are summarized and recommendations for improvements in the benchmark are made. (author)

Neutron fluence determination for light water reactor pressure vessels

International Nuclear Information System (INIS)

Gold, R.

1994-01-01

A general description of limitations that exist in pressure vessel neutron fluence determinations for commercial light water reactors is presented. Complexity factors that arise in light water reactor pressure vessel neutron fluence calculations are identified and used to analyze calculational limitations. Two broad categories of calculational limitations are introduced, namely benchmark field limitations and deep penetration limitations. Explicit examples of limitations that can arise in each of these two broad categories are presented. These limitations are used to show that the recent draft regulatory guide for the determination of pressure vessel neutron fluence, developed by the Nuclear Regulatory Commission, is based upon procedures and assumptions that are not valid. To eliminate the complexity and limitations of calculational methods, it is recommended that the determination of light water reactor pressure vessel neutron fluence be based upon experiment. Recommendations for improved methods of pressure vessel surveillance neutron dosimetry are advanced

Decommissioning of reactor facilities (2). Required technology

International Nuclear Information System (INIS)

Yanagihara, Satoshi

2014-01-01

Decommissioning of reactor facilities was planned to perform progressive dismantling, decontamination and radioactive waste disposal with combination of required technology in a safe and economic way. This article outlined required technology for decommissioning as follows: (1) evaluation of kinds and amounts of residual radioactivity of reactor facilities with calculation and measurement, (2) decontamination technology of metal components and concrete structures so as to reduce worker's exposure and production of radioactive wastes during dismantling, (3) dismantling technology of metal components and concrete structures such as plasma arc cutting, band saw cutting and controlled demolition with mostly remote control operation, (3) radioactive waste disposal for volume reduction and reuse, and (4) project management of decommissioning for safe and rational work to secure reduction of worker's exposure and prevent the spreading of contamination. (T. Tanaka)

Examination of VVER-1000 Reactor Pressure Vessel

International Nuclear Information System (INIS)

Matokovic, A.; Picek, E.; Markulin, K.

2008-01-01

The increasing demand of a higher level of safety in the operation of the nuclear power plants requires the utilisation of more precise automated equipment to perform in-service inspections. That has been achieved by technological advances in computer technology, in robotics, in examination probe technology with the development of the advanced inspection technique and has also been due to the considerable and varied experience gained in the performance of such inspections. In-service inspection of reactor pressure vessel, especially Russian-designed WWER-1000 presents one of the most important and extensive examination of nuclear power plants primary circuit components. Such examination demand high standards of inspection technology, quality and continual innovation in the field of non-destructive testing advanced technology. A remote underwater contact ultrasonic technique is employed for the examination of the base metal of vessel and reactor welds, whence eddy current method is applied for clad surface examinations. Visual testing is used for examination of the vessel interior. The movement of inspection probes and data positioning are assured by using new reactor pressure vessel tool concept that is fully integrated with inspection systems. The successful performance of reactor pressure vessel is attributed thorough pre-outage planning, training and successful performance demonstration qualification of chosen non-destructive techniques on the specimens with artificial and/or real defects. Furthermore, use of advanced approach of inspection through implementation the state-of-the-art examination equipment significantly reduced the inspection time, radiation exposure to examination personnel, shortening nuclear power plant outage and cutting the total inspection costs. This paper presents advanced approach in the reactor pressure vessel in-service inspections and it is especially developed for WWER-1000 nuclear power plants.(author)

Investigation of the failure of a reactor pressure vessel by plastic instability

International Nuclear Information System (INIS)

Laemmer, H.; Ritter, B.

1994-01-01

A possible consequence of a core meltdown accident in a pressurized water reactor is the failure of the reactor pressure vessel under high internal pressure. With the aid of the finite element program ABAQUS and using a material model of the thermo-plasticity for large deformation, the failure of the reactor pressure vessel due to plastic instability was examined. It was apparent from the finite element calculations that solely due to reduction in strength of the material, even for internal wall temperatures clearly below the core melt; of about 2000 C, the critical internal pressure can fall to values which are lower than the working pressure. With the aid of simplified geometry, a lower limit for the pressure at failure of the reactor pressure vessel can be calculated. (orig./HP) [de

Application and development of dismantling technologies for decommissioning of nuclear installations

International Nuclear Information System (INIS)

Bach, W.; Kremer, G.; Ruemenapp, T.

2006-01-01

The decommissioning of nuclear installations poses a challenge to high performance underwater cutting technologies because of complex limiting conditions, like radioactive contamination, accessibility, geometry of work piece, material thickness and composition. For the safe dismantling of the moderator tank and the thermal shield of the Multi-purpose Research Reactor (MZFR) Karlsruhe the development and the use of thermal cutting tools will be demonstrated, in this case the underwater plasma arc cutting and the contact arc metal cutting (CAMC). (orig.)

Structural integrity evaluation of PWR nuclear reactor pressure vessels

International Nuclear Information System (INIS)

Cruz, Julio R.B.; Mattar Neto, Miguel

1999-01-01

The reactor pressure vessel (RPV) is the most important structural component of a PWR nuclear power plant. It contains the reactor core and is the main component of the primary system pressure boundary, the system responsible for removing the heat generated by the nuclear reactions. It is considered not replaceable and, therefore, its lifetime is a key element to define the plant life as a whole. Three critical issues related to the reliability of the RPV structural integrity come out by reason of the radiation damage imposed to the vessel material during operation. These issues concern the definition of pressure versus temperature limits for reactor heatup and cooldown, pressurized thermal shock evaluation and assessment of reactor vessels with low upper shelf Charpy impact energy levels. This work aims to present the major aspects related to these topics. The requirements for preventing fracture of the RPV are reviewed as well as the available technology for assessing the safety margins. For each mentioned problem, the several steps for structural integrity evaluation are described and the analysis methods are discussed. (author)

The installation welding of pressure water reactor coolant piping

International Nuclear Information System (INIS)

Deng Feng

2010-01-01

Large pressure water reactor nuclear power plants are constructing in our country. There are three symmetry standard loops in reactor coolant system. Each loop possesses a steam generator and a primary poop, in which one of the loops is equipped with a pressurizer. These components are connected with reactor pressure vessel by installation welding of the coolant piping. The integrity of reactor coolant pressure boundary is the second barrier to protect the radioactive substance from release to outside, so the safe operation of nuclear power plant is closely related to the quality of coolant piping installation welding. The heavy tube with super low carbon content austenitic stainless steel is selected for coolant piping. This kind of material has good welding behavior, but the poor thermal conductivity, the big liner expansion coefficient and the big welding deformation will cause bigger welding stress. To reduce the welding deformation, to control the dimension precision, to reduce the residual stress and to ensure the welding quality the installation sequence should be properly designed and the welding technology should be properly controlled. (authors)

Reactor core and passive safety systems descriptions of a next generation pressure tube reactor - mechanical aspects

Energy Technology Data Exchange (ETDEWEB)

Yetisir, M.; Gaudet, M.; Rhodes, D.; Hamilton, H.; Pencer, J. [Atomic Energy of Canada Limited, Chalk River, ON (Canada)

2014-07-01

Canada has been developing a channel-type supercritical water-cooled nuclear reactor concept, often called the Canadian SCWR. The objective of this reactor concept is to meet the technology goals of the Generation IV International Forum (GIF) for the next generation nuclear reactor development, which include enhanced safety features (inherent safe operation and deploying passive safety features), improved resource utilization, sustainable fuel cycle, and greater proliferation resistance than Generation III nuclear reactors. The Canadian SCWR core concept consists of a high-pressure inlet plenum, a separate low-pressure heavy water moderator contained in a calandria vessel, and 336 pressure tubes surrounded by the moderator. The reactor uses supercritical water as a coolant, and a direct steam power cycle to generate electricity. The reactor concept incorporates advanced safety features such as passive core cooling, long-term decay heat rejection to the environment and fuel melt prevention via passive moderator cooling. These features significantly reduce core damage frequency relative to existing nuclear reactors. This paper presents a description of the design concepts for the Canadian SCWR core, reactor building layout and the plant layout. Passive safety concepts are also described that address containment and core cooling following a loss-of coolant accident, as well as long term reactor heat removal at station blackout conditions. (author)

Design study on steam generator integration into the VVER reactor pressure vessel

International Nuclear Information System (INIS)

Hort, J.; Matal, O.

2004-01-01

The primary circuit of VVER (PWR) units is arranged into loops where the heat generated by the reactor is removed by means of main circulating pumps, loop pipelines and steam generators, all located outside the reactor pressure vessel. If the primary circuit and reactor core were integrated into one pressure vessel, as proposed, e.g., within the IRIS project (WEC), a LOCA situation would be limited by the reactor pressure vessel integrity only. The aim of this design study regarding the integration of the steam generator into the reactor pressure vessel was to identify the feasibility limits and some issues. Fuel elements and the reactor pressure vessel as used in the Temelin NPP were considered for the analysis. From among the variants analyzed, the variant with steam generators located above the core and vertically oriented circulating pumps at the RPV lower bottom seems to be very promising for future applications

Thermohydraulic analysis of pressurized water reactors

International Nuclear Information System (INIS)

Veloso, M.A.

1980-01-01

The computer program PANTERA is applied in the thermo-hydraulic analysis of Pressurized Water Reactor Cores (PWR). It is a version of COBRA-IIIC in which a new thermal conduction model for fuel rods was introduced. The results calculated by this program are compared with experimental data obtained from bundles of fuel rods, simulating reactor conditions. The validity of the new thermal model is checked too. The PANTERA code, through a simplified procedure of calculation, is used in the thermo-hydraulic analysis of Indian Point, Unit 2, reactor core, in stationary conditions. The results are discussed and compared with design data. (Autor) [pt

Standard Technical Specifications for Combustion Engineering Pressurized Water Reactors

International Nuclear Information System (INIS)

Vito, D.J.

1980-12-01

The Standard Technical Specifications for Combustion Engineering Pressurized Water Reactors (CE-STS) is a generic document prepared by the US NRC for use in the licensing process of current Combustion Engineering Pressurized Water Reactors. The CE-STS sets forth the limits, operating conditions, and other requirements applicable to nuclear reactor facility operation as set forth by Section 50.36 of 10 CFR 50 for the protection of the health and safety of the public. The document is revised periodically to reflect current licensing requirements

Pressurized water reactor fuel rod design methodology

International Nuclear Information System (INIS)

Silva, A.T.; Esteves, A.M.

1988-08-01

The fuel performance program FRAPCON-1 and the structural finite element program SAP-IV are applied in a pressurized water reactor fuel rod design methodology. The applied calculation procedure allows to dimension the fuel rod components and characterize its internal pressure. (author) [pt

Light Water Reactor-Pressure Vessel Surveillance project computer system

International Nuclear Information System (INIS)

Merriman, S.H.

1980-10-01

A dedicated process control computer has been implemented for regulating the metallurgical Pressure Vessel Wall Benchmark Facility (PSF) at the Oak Ridge Research Reactor. The purpose of the PSF is to provide reliable standards and methods by which to judge the radiation damage to reactor pressure vessel specimens. Benchmark data gathered from the PSF will be used to improve and standardize procedures for assessing the remaining safe operating lifetime of aging reactors. The computer system controls the pressure vessel specimen environment in the presence of gamma heating so that in-vessel conditions are simulated. Instrumented irradiation capsules, in which the specimens are housed, contain temperature sensors and electrical heaters. The computer system regulates the amount of power delivered to the electrical heaters based on the temperature distribution within the capsules. Time-temperature profiles are recorded along with reactor conditions for later correlation with specimen metallurgical changes

Pressure vessel for nuclear reactors

International Nuclear Information System (INIS)

1975-01-01

The invention applies to a pressure vessel for nuclear reactors whose shell, made of cast metal segments, has a steel liner. This liner must be constructed to withstand all operational stresses and to be easily repairable. The invention solves this problem by installing the liner at a certain distance from the inner wall of the pressure vessel shell and by filling this clearance with supporting concrete. Both the concrete and the steel liner must have a lower prestress than the pressure vessel shell. In order to avoid damage to the liner when prestressing the pressure vessel shell, special connecting elements are provided which consist of welded-on fastening elements projecting into recesses in the cast metal segments of the pressure vessel. Their design is described in detail. (TK) [de

Information report published in application of article 146 of the Regulation by the Commission of information related to the technical and financial feasibility of the dismantling of basic nuclear installations on the behalf of the Commission for sustainable development and land planning. Nr 4428

International Nuclear Information System (INIS)

Aubert, Julien; Romagnan, Barbara

2017-01-01

Based on visits, on hearings and on debates within the Commission, this report addresses the issue of the technical and financial feasibility of the dismantling of nuclear installations. Indeed, it appears that the technical feasibility is not as mastered as supposed, and that dismantling works will last longer than foreseen, with therefore a higher cost than foreseen. Thus, existing and foreseen funding might be insufficient, and the global strategy for dismantling should be seriously reviewed regarding both technical and financial points of view. Before reaching this conclusion, the report presents the general context: definition of dismantling, perspective of development of dismantling activities, specific case of marine reactors. The authors then present and comment initial basic principles (extrapolation with the Dampierre model, immediate dismantling, soil decontamination) and parameters which could result in cost reduction. The second part of the report discusses the technical issue, first by recalling and commenting the difficulties faced by EDF to dismantle its first reactors (case of Brennilis, complete shift by EDF regarding its strategy for graphite-gas reactors, case of Superphenix), secondly by outlining that waste management largely determines dismantling (situation for the different types of wastes, problem of saturation of some centres, issue of a release threshold, case of wastes from graphite-gas reactors), and thirdly by discussing the issue of subcontracting. The third part addresses the financial issue and EDF funding by discussing assessment principles and method used by EDF, by showing that the result is probably an under-assessment (due to optimistic hypotheses, to many unfunded expenses, and to under-assessed dismantling costs). The authors then compare the French situation with other countries (Germany, USA, Belgium, OECD countries) to show that institutional comparisons are consistent with each other. They propose a more detailed

Pressurized water reactor simulator. Workshop material

International Nuclear Information System (INIS)

2003-01-01

The International Atomic Energy Agency (IAEA) has established an activity in nuclear reactor simulation computer programs to assist its Member States in education. The objective is to provide, for a variety of advanced reactor types, insight and practice in their operational characteristics and their response to perturbations and accident situations. To achieve this, the IAEA arranges for the development and distribution of simulation programs and educational material and sponsors courses and workshops. The workshops are in two parts: techniques and tools for reactor simulator development; and the use of reactor simulators in education. Workshop material for the first part is covered in the IAEA Training Course Series No. 12, 'Reactor Simulator Development' (2001). Course material for workshops using a WWER- 1000 reactor department simulator from the Moscow Engineering and Physics Institute, the Russian Federation is presented in the IAEA Training Course Series No. 21 'WWER-1000 Reactor Simulator' (2002). Course material for workshops using a boiling water reactor simulator developed for the IAEA by Cassiopeia Technologies Incorporated of Canada (CTI) is presented in the IAEA publication: Training Course Series No.23 'Boiling Water Reactor Simulator' (2003). This report consists of course material for workshops using a pressurized water reactor simulator

EPR (European Pressurized water Reactor) The advanced nuclear reactor

International Nuclear Information System (INIS)

2004-01-01

Nuclear energy, which provides a steady supply of electricity at low cost, has its rightful place in the energy mix of the 21. century, which puts the emphasis on sustainable development. The EPR is the only 3. generation reactor under construction today. It is an evolutionary reactor that represents a new generation of pressurized water reactors with no break in the technology used for the most recent models. The EPR was developed by Framatome and Siemens, whose nuclear activities were combined in January 2001 to form Framatome ANP, a subsidiary of AREVA and Siemens. EDF and the major German electricity companies played an active part in the project. The safety authorities of the two countries joined forces to bring their respective safety standards into line and draw up joint design rules for the new reactor. The project had three objectives: meet the requirements of European utilities, comply with the safety standards laid down by the French safety authority for future pressurized water reactors, in concert with its German counterpart, and make nuclear energy even more competitive than energy generated using fossil fuels. The EPR can guarantee a safe, inexpensive electricity supply, without adding to the greenhouse effect. It meets the requirements of the safety authorities and lives up to the expectations of electricity utilities. This document presents the main characteristics of the EPR, and in particular the additional measures to prevent the occurrence of events likely to damage the core, the leak-tight containment, the measures to reduce the exposure of operating and maintenance personnel, the solutions for an even greater protection of the environment. The foreseen development of the EPR in France and abroad (Finland, China, the United States) is summarized

The inner containment of an EPR trademark pressurized water reactor

Energy Technology Data Exchange (ETDEWEB)

Ostermann, Dirk; Krumb, Christian; Wienand, Burkhard [AREVA GmbH, Offenbach (Germany)

2014-08-15

On February 12, 2014 the containment pressure and subsequent leak tightness tests on the containment of the Finnish Olkiluoto 3 EPR trademark reactor building were completed successfully. The containment of an EPR trademark pressurized water reactor consists of an outer containment to protect the reactor building against external hazards (such as airplane crash) and of an inner containment that is subjected to internal overpressure and high temperature in case of internal accidents. The current paper gives an overview of the containment structure, the design criteria, the validation by analyses and experiments and the containment pressure test.

Thermohydraulic feedbacks in self-pressurized reactor systems

International Nuclear Information System (INIS)

Fiebig, R.

1977-01-01

The impact on the dynamic behaviour of a self-pressurized reactor by the thermodynamic properties of the steam dome is investigated. For self-stabilization of the system the water of the primary circuit must be coupled thermodynamically to the steam in the steam dome, or alternatively the water in the reactor core must be subcooled sufficiently. Ways of thermodynamically coupling the water to the steam are heat conduction, boiling and condensation. A heat sink within the steam dome forces thermodynamic equilibrium between water and steam. This condition yields excellent self-control. Without heat sink thermal coupling is suspended at transients resulting in pressure rises. However, the reactor is still controlable as long as circuit and steam dome have direct contact. At the reactor of the NCS-80 a buffer volume of water separates primary circuit and steam volume. Stability is achieved by a heat sink in the steam dome and a shift of the core temperature into the subcooled domain effected by steam bubbles rising into the steam dome. (orig.) [de

Thermohydraulic feedbacks in self-pressurized reactor systems

International Nuclear Information System (INIS)

Fiebig, R.

1977-01-01

The impact on the dynamic behaviour of a self-pressurized reactor by the thermodynamic properties of the steam dome is investigated. For self-stabilization of the system the water of the primary circuit must be coupled thermodynamically to the steam in the steam dome, or alternatively the water in the reactor core must be subcooled sufficiently. Ways of thermodynamically coupling the water to the steam are heat conduction, boiling and condensation. A heat sink within the steam dome forces thermodynamic equilibrium between water and steam. This condition yields excellent self-control. Without heat sink thermal coupling is suspended at transients resulting in pressure rises. However, the reactor is still controllable as long as circuit and steam dome have direct contact. At the reactor of the NCS-80 a buffer volume of water separates primary circuit and steam volume. Stability is achieved by a heat sink in the steam dome and a shift of the core temperature into the subcooled domain effected by steam bubbles rising into the steam dome. (orig.) [de

Cascading pressure reactor and method for solar-thermochemical reactions

Science.gov (United States)

Ermanoski, Ivan

2017-11-14

Reactors and methods for solar thermochemical reactions are disclosed. The reactors and methods include a cascade of reduction chambers at successively lower pressures that leads to over an order of magnitude pressure decrease compared to a single-chambered design. The resulting efficiency gains are substantial, and represent an important step toward practical and efficient solar fuel production on a large scale.

Development of a pressurizer level compensator for use on N Reactor

International Nuclear Information System (INIS)

Bussell, J.H.

1985-07-01

The instrument described in this report has been developed to compensate the measured water level in the N Reactor pressurizer for temperature effects. N Reactor is a pressurized water nuclear reactor (PWR). The instrument is defined as a pressurizer level compensator (PLC). A pressurizer is used in a PWR to control the primary coolant pressure and provide a surge volume for primary coolant expansion and contraction. A means of compensating for water and steam density is required because of the wide range of pressure and temperature that result from different steady state and transient reactor power levels. The uncompensated level is determined by measurement of differential pressure between the top of the level measurement zone and the bottom of the level measurement zone. Temperature of the water in the pressurizer is the parameter that is used to determine the proper level compensation since water and steam density are primarily functions of temperature in this case. The PLC uses a microprocessor to calculate the compensated level from temperature and differential pressure measurements. This report includes a description of the design, development, and implementation of software and hardware that are in the PLC. 9 refs., 51 figs., 17 tabs

Decommissioning of nuclear facilities: COGEMA expertise devoted to UP1 reprocessing plant dismantling programme

International Nuclear Information System (INIS)

Gay, A.

2001-01-01

Over the last past decades, the French nuclear industry has acquired a great experience and know-how in the field of dismantling. Today this experience amounts to more than 200,000 hours. The fundamental aims within dismantling strategy are the same as for all nuclear facilities: minimising doses received by workers, minimising waste volume and adapting waste management to radioactivity levels, minimising costs. French experience is based on technologies which are currently used in nuclear maintenance facilities. Dismantling is a dynamic process especially in the field of decontamination (chemical and mechanical), cleaning, robotics and remote control operations. The strategy for the dismantling of former UP1 reprocessing plant is based on the feedback of experience gained through the dismantling of other facilities such as the AT1 workshop at La Hague. This workshop, a pilot plant for reprocessing of fast-breeder reactor fuels (Rapsodie and Phenix) has to be dismantled to IAEA level 3 (unrestricted site use), excluding civil works structures. Currently conducted by trained shifts, this dismantling project should end in 1999. The experience already acquired proves that chemical rinsings with the use of specific reagents is sufficient to decontaminate the hot cells and that the use of remote operations or robotics is not as important as previously envisaged. The UP1 reprocessing plant of Marcoule operated from 1958 to 1997. End of the operation was pronounced on the 31st of December 1997. 20,000 tons of spent fuels were reprocessed at UP1. The cleaning and dismantling operations at the Marcoule site depend upon the CEA, EDF and COGEMA. The Defence and Industry Ministries asked for a specific structure to be set up. An economic interest group called CODEM was created in May 1996. CODEM decides, finances and supervises dismantling operations, while respecting the constraints of nuclear safety, environmental protection and cost-effectiveness. The cleaning operations of

BWR [boiling-water reactor] and PWR [pressurized-water reactor] off-normal event descriptions

International Nuclear Information System (INIS)

1987-11-01

This document chronicles a total of 87 reactor event descriptions for use by operator licensing examiners in the construction of simulator scenarios. Events are organized into four categories: (1) boiling-water reactor abnormal events; (2) boiling-water reactor emergency events; (3) pressurized-water reactor abnormal events; and (4) pressurized-water reactor emergency events. Each event described includes a cover sheet and a progression of operator actions flow chart. The cover sheet contains the following general information: initial plant state, sequence initiator, important plant parameters, major plant systems affected, tolerance ranges, final plant state, and competencies tested. The progression of operator actions flow chart depicts, in a flow chart manner, the representative sequence(s) of expected immediate and subsequent candidate actions, including communications, that can be observed during the event. These descriptions are intended to provide examiners with a reliable, performance-based source of information from which to design simulator scenarios that will provide a valid test of the candidates' ability to safely and competently perform all licensed duties and responsibilities

Pilot tests for dismantling by blasting of the biological shield of a shut down nuclear power station

International Nuclear Information System (INIS)

Freund, H.U.

1995-01-01

Following free-field tests on concrete blocks the feasibility of explosive dismantling of the biological shield of nuclear power stations has been succesfully tested at the former hotsteam reaction in Karlstein/Main Germany. For this purpose a model shield of scale 1:2 was embedded into the reactor structure at which bore-hole blasting tests employing up to about 15 kg of explosive were performed. An elaborate measurement system allowed to receive detailed information on the blast side-effects: Special emphasis was focussed on the quantitative registration of the dynamic blast loads; data for the transfer of the dismantling method to the removal of real ractor structures were obtained. (orig.) [de

Decommissioning technology development for research reactors

International Nuclear Information System (INIS)

Lee, K. W.; Kim, S. K.; Kim, Y. K.

2004-03-01

Although it is expected that the decommissioning of a nuclear power plant will happen since 2020, the need of partial decommissioning and decontamination for periodic inspection and life extension has been on an increasing trend and domestic market has gradually been extended. Therefore, in this project the decommissioning DB system on the KRR-1 and 2 was developed as establishing the information classification system of the research reactor dismantling and the structural design and optimization of the decommissioning DB system. Also in order to secure the reliability and safety about the dismantling process, the main dismantling simulation technology that can verify the dismantling process before their real dismantling work was developed. And also the underwater cutting equipment was developed to remove these stainless steel parts highly activated from the RSR. First, the its key technologies were developed and then the design, making, and capability analysis were performed. Finally the actual proof was achieved for applying the dismantling site. an automatic surface contamination measuring equipment was developed in order to get the sample automatically and measure the radiation/radioactivity

Jose Cabrera dismantling and decommissioning project

International Nuclear Information System (INIS)

Ondaro, Manuel

2013-01-01

The Jose Cabrera Nuclear Power Plant (NPP) was the first commercial power reactor (Westinghouse 1 loop PWR 510 MWth, 160 MWe) commissioned in Spain and provided the base for future development and training. The reactor construction started in 1963 and it was officially on-line by 1969. The NPP operated from 1969 until 2006 when it became the first reactor to be shut down after completing its operational period. The containment is reinforced concrete with a stainless steel head. In 2010 responsibility for D and D was transferred to Enresa to achieve IAEA level 3 (a green field site available for unrestricted re-uses) by 2017. Of the total of more than 104,000 tons of materials that will be generated during dismantling, it is estimated that only ∼4,000 tons will be radioactive waste, some of which, 40 t are considered as intermediate level long-lived wastes and the rest (3,960 t) will be categorized as VLLW and ILLW. The Project is divided into five phases: Phase 0 - Removal of fuel and preliminary work.. Phase 1 - Preparatory Activities for D and D. complete. Phase 2 - Dismantling of Major Components. Phase 3 - Removal of Auxiliary Installations, Decontamination and Demolition. Phase 4 - Environmental Restoration. Phase 2, is currently ongoing (50% completed). To manage the diverse aspects of decommissioning operations, Enresa uses an internally developed computerized project management tool. The tool, based on knowledge gathered from other Enresa projects, can process operations management, maintenance operations, materials, waste, storage areas, procedures, work permits, operator dose management and records. Enresa considers that communication is important for both internal and external stakeholder relations and can be used to inform, to neutralize negative opinions and attitudes, to remove false expectations and for training. Enresa has created a new multi-purpose area (exhibition/visitor centre) and encourages visits from the public, local schools, local and

Jose Cabrera dismantling and decommissioning project

Energy Technology Data Exchange (ETDEWEB)

Ondaro, Manuel [ENRESA, Madrid (Spain)

2013-07-01

The Jose Cabrera Nuclear Power Plant (NPP) was the first commercial power reactor (Westinghouse 1 loop PWR 510 MWth, 160 MWe) commissioned in Spain and provided the base for future development and training. The reactor construction started in 1963 and it was officially on-line by 1969. The NPP operated from 1969 until 2006 when it became the first reactor to be shut down after completing its operational period. The containment is reinforced concrete with a stainless steel head. In 2010 responsibility for D and D was transferred to Enresa to achieve IAEA level 3 (a green field site available for unrestricted re-uses) by 2017. Of the total of more than 104,000 tons of materials that will be generated during dismantling, it is estimated that only ∼4,000 tons will be radioactive waste, some of which, 40 t are considered as intermediate level long-lived wastes and the rest (3,960 t) will be categorized as VLLW and ILLW. The Project is divided into five phases: Phase 0 - Removal of fuel and preliminary work.. Phase 1 - Preparatory Activities for D and D. complete. Phase 2 - Dismantling of Major Components. Phase 3 - Removal of Auxiliary Installations, Decontamination and Demolition. Phase 4 - Environmental Restoration. Phase 2, is currently ongoing (50% completed). To manage the diverse aspects of decommissioning operations, Enresa uses an internally developed computerized project management tool. The tool, based on knowledge gathered from other Enresa projects, can process operations management, maintenance operations, materials, waste, storage areas, procedures, work permits, operator dose management and records. Enresa considers that communication is important for both internal and external stakeholder relations and can be used to inform, to neutralize negative opinions and attitudes, to remove false expectations and for training. Enresa has created a new multi-purpose area (exhibition/visitor centre) and encourages visits from the public, local schools, local and

Measurement and analysis of pressure tube elongation in the Douglas Point reactor

International Nuclear Information System (INIS)

Causey, A.R.; MacEwan, S.R.; Jamieson, H.C.; Mitchell, A.B.

1980-02-01

Elongations of zirconium alloy pressure tubes in CANDU reactors, which occur as a result of neutron-irradiation-induced creep and growth, have been measured over the past 6 years, and the consequences of thses elongations have recently been analysed. Elongation rates, previously deduced from extensive measurements of elongations of cold-worked Zircaloy-2 pressure tubes in the Pickering reactors, have been modified to apply to the pressure tubes in the Douglas Point (DP) reactor by taking into account measured diffences in texture and dislocation density. Using these elongation rates, and structural data unique to the DP reactor, the analysis predicts elongation behaviour which is in good agreement with pressure tube elongations measured during the ten years of reactor operation. (Auth)

Development of Zr-2.5Nb pressure tubes for Advanced CANDU Reactor

International Nuclear Information System (INIS)

Bickel, G.A.; Griffiths, M.; Douchant, A.; Douglas, S.; Woo, O.T.; Buyers, A.

2010-01-01

In an Advanced CANDU Reactor (ACR), pressure tubes of cold-worked Zr-2.5Nb materials will be used in the reactor core to contain the fuel bundles and the light water coolant. They will be subjected to higher temperature, pressure and flux than that in a CANDU reactor. In order to ensure that these tubes will perform acceptably over their 30-year design life in such an environment, a manufacturing process has been developed to produce 6.5 mm thick ACR pressure tubes with optimized chemical composition, improved mechanical properties and in-reactor behaviour. The test and examination results show that, when compared with current in-service pressure tubes, the mechanical properties of ACR pressure tubes are significantly improved. Based on previous experience with CANDU reactor pressure tubes an assessment of the grain structure and texture indicates that the in-reactor creep deformation will be improved also. Analysis of the distribution of texture parameters from a trial batch of 26 tubes shows that the variability is reduced relative to tubes fabricated in the past. This reduction in variability together with a shift to a coarser grain structure will result in a reduction in diametral creep design limits and thus a longer economic life for the fuel channels of the advanced CANDU reactor. (author)

Dismantling of transuranic contaminated facilities

International Nuclear Information System (INIS)

Roux, P.

1985-01-01

The dismantling of transuranic contaminated facilities raises specific problems. A large part of these problems relates to the management of the waste resulting from dismantling. From the experience gained in the different centers CEA and COGEMA it appears that there are industrial solutions in the group CEA and that an engineering company such as SGN can export them [fr

Machine for dismantling metal parts

Energy Technology Data Exchange (ETDEWEB)

Prokopov, O.I.; Loginovskiy, V.I.; Yagudin, S.Z.

1982-01-01

The purpose of the invention is to reduce the outlays of time for dismantling metal parts under conditions of eliminating open gas and oil gushers in operational drilling. This goal is achieved because the machine for dismantling the metal parts is equipped with a set of clamping elements arranged on the chassis, where each of them has a drive.

Conceptual mechanical design for a pressure-tube type supercritical water-cooled reactor

Energy Technology Data Exchange (ETDEWEB)

Yetisir, M.; Diamond, W.; Leung, L.K.H.; Martin, D.; Duffey, R. [Atomic Energy of Canada Limited, Chalk River, ON (Canada)

2011-07-01

This paper presents a conceptual mechanical design for a heavy-water-moderated pressure-tube supercritical water (SCW) reactor, which has evolved from the well-established CANDU nuclear reactor. As in the current designs, the pressure-tube SCW reactor uses a calandria vessel and, as a result, many of today's technologies (such as the shutdown safety systems) can readily be adopted with small changes. Because the proposed concept uses a low-pressure moderator, it does not require a pressure vessel that is subject to the full SCW pressure and temperature conditions. The proposed design uses batch refueling and hence, the reactor core is orientated vertically. Significant simplifications result in the design with the elimination of on line fuelling systems, fuel channel end fittings and fuel channel closure seals and thus utilize the best features of Light Water Reactor (LWR) and Heavy Water Reactor (HWR) technologies. The safety goal is based on achieving a passive 'no core melt' configuration for the channels and core, so the mechanical features and systems directly reflect this desired attribute. (author)

Conceptual mechanical design for a pressure-tube type supercritical water-cooled reactor

International Nuclear Information System (INIS)

Yetisir, M.; Diamond, W.; Leung, L.K.H.; Martin, D.; Duffey, R.

2011-01-01

This paper presents a conceptual mechanical design for a heavy-water-moderated pressure-tube supercritical water (SCW) reactor, which has evolved from the well-established CANDU nuclear reactor. As in the current designs, the pressure-tube SCW reactor uses a calandria vessel and, as a result, many of today's technologies (such as the shutdown safety systems) can readily be adopted with small changes. Because the proposed concept uses a low-pressure moderator, it does not require a pressure vessel that is subject to the full SCW pressure and temperature conditions. The proposed design uses batch refueling and hence, the reactor core is orientated vertically. Significant simplifications result in the design with the elimination of on line fuelling systems, fuel channel end fittings and fuel channel closure seals and thus utilize the best features of Light Water Reactor (LWR) and Heavy Water Reactor (HWR) technologies. The safety goal is based on achieving a passive 'no core melt' configuration for the channels and core, so the mechanical features and systems directly reflect this desired attribute. (author)

Feedback from Westinghouse experience on segmentation of reactor vessel internals - 59013

International Nuclear Information System (INIS)

Kreitman, Paul J.; Boucau, Joseph; Segerud, Per; Fallstroem, Stefan

2012-01-01

With more than 25 years of experience in the development of reactor vessel internals segmentation and packaging technology, Westinghouse has accumulated significant know-how in the reactor dismantling market. Building on tooling concepts and cutting methodologies developed decades ago for the successful removal of nuclear fuel from the damaged Three Mile Island Unit 2 reactor (TMI-2), Westinghouse has continuously improved its approach to internals segmentation and packaging by incorporating lessons learned and best practices into each successive project. Westinghouse has developed several concepts to dismantle reactor internals based on safe and reliable techniques, including plasma arc cutting (PAC), abrasive water-jet cutting (AWJC), metal disintegration machining (MDM), or mechanical cutting. Westinghouse has applied its technology to all types of reactors covering Pressurized Water Reactors (PWR's), Boiling Water Reactors (BWR's), Gas Cooled Reactors (GCR's) and sodium reactors. The primary challenges of a segmentation and packaging project are to separate the highly activated materials from the less-activated materials and package them into appropriate containers for disposal. Since space is almost always a limiting factor it is therefore important to plan and optimize the available room in the segmentation areas. The choice of the optimum cutting technology is important for a successful project implementation and depends on some specific constraints like disposal costs, project schedule, available areas or safety. Detailed 3-D modeling is the basis for tooling design and provides invaluable support in determining the optimum strategy for component cutting and disposal in waste containers, taking account of the radiological and packaging constraints. Westinghouse has also developed a variety of special handling tools, support fixtures, service bridges, water filtration systems, video-monitoring systems and customized rigging, all of which are required for a

Fuel rod bundles proposed for advanced pressure tube nuclear reactors

International Nuclear Information System (INIS)

Prodea, Iosif; Catana, Alexandru

2010-01-01

The paper aims to be a general presentation for fuel bundles to be used in Advanced Pressure Tube Nuclear Reactors (APTNR). The characteristics of such a nuclear reactor resemble those of known advanced pressure tube nuclear reactors like: Advanced CANDU Reactor (ACR TM -1000, pertaining to AECL) and Indian Advanced Heavy Water Reactor (AHWR). We have also developed a fuel bundle proposal which will be referred as ASEU-43 (Advanced Slightly Enriched Uranium with 43 rods). The ASEU-43 main design along with a few neutronic and thermalhydraulic characteristics are presented in the paper versus similar ones from INR Pitesti SEU-43 and CANDU-37 standard fuel bundles. General remarks regarding the advantages of each fuel bundle and their suitability to be burned in an APTNR reactor are also revealed. (authors)

Reactor pressure vessel steels

International Nuclear Information System (INIS)

Van De Velde, J.; Fabry, A.; Van Walle, E.; Chaouuadi, R.

1998-01-01

Research and development activities related to reactor pressure vessel steels during 1997 are reported. The objectives of activities of the Belgian Nuclear Research Centre SCK/CEN in this domain are: (1) to develop enhanced surveillance concepts by applying micromechanics and fracture-toughness tests to small specimens, and by performing damage modelling and microstructure characterization; (2) to demonstrate a methodology on a broad database; (3) to achieve regulatory acceptance and industrial use

Assessment of Loss-of-Coolant Effect on Pressurized Heavy Water Reactors

International Nuclear Information System (INIS)

Kim, Won Young; Park, Joo Hwan; Kim, Bong Ghi

2009-01-01

A CANDU reactor is a heavy-water-moderated, natural uranium fuelled reactor with a pressure tube. The reactor contains a horizontal cylindrical vessel (calandria) and each pressure tube is isolated from the heavy-water moderator in a calandria. This allows the moderator system to be operated of a high-pressure and of a high-temperature coolant in pressure tube. This causes the pressurized liquid coolant in the channel to void and therefore give rise to a reactivity transient in the event of a break or fault in the coolant circuit. In particular, all CANDU reactors are well known to have a positive void reactivity coefficient and thus this phenomenon may lead to a positive feedback, which can cause a large power pulse. We assess the loss-of-coolant effect by coolant void reactivity versus fuel burnup, four factor parameters for fresh fuel and equilibrium fuel, reactivity change due to the change of coolant density and reactivity change in the case of half- and full-core coolant

Renovation of the sealing planes of WWER-400 reactors pressure vessel

International Nuclear Information System (INIS)

Jablonicky, P.; Pilat, P.

2007-01-01

An article describes technical solution for renovation of the sealing planes of WWER-440 reactor's pressure vessel. Four nickel sealing rings placed in four concentric grooves are providing hermetic sealing between the vessel and the lid of this type of the reactor. Impeccable seal of the reactor's pressure vessel, where the fission reaction takes place, represents a basic security factor for safe electric energy production. Principle of renovation of the reactor's pressure vessel and lid sealing planes is based on mechanical enlargement of defective grooves and following cladding of the new material by TIG welding. Final step for renovation includes machining of new grooves according to geometrical and surface quality requirements (Authors)

Radiation effects on reactor pressure vessel supports

International Nuclear Information System (INIS)

Johnson, R.E.

1996-05-01

The purpose of this report is to present the findings from the work done in accordance with the Task Action Plan developed to resolve the Nuclear Regulatory Commission (NRC) Generic Safety Issue No. 15, (GSI-15). GSI-15 was established to evaluate the potential for low-temperature, low-flux-level neutron irradiation to embrittle reactor pressure vessel (RPV) supports to the point of compromising plant safety. An evaluation of surveillance samples from the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) had suggested that some materials used for RPV supports in pressurized-water reactors could exhibit higher than expected embrittlement rates. However, further tests designed to evaluate the applicability of the HFIR data to reactor RPV supports under operating conditions led to the conclusion that RPV supports could be evaluated using traditional method. It was found that the unique HFIR radiation environment allowed the gamma radiation to contribute significantly to the embrittlement. The shielding provided by the thick steel RPV shell ensures that degradation of RPV supports from gamma irradiation is improbable or minimal. The findings reported herein were used, in part, as the basis for technical resolution of the issue

Pressure test method for reactor pressure vessel in construction field

International Nuclear Information System (INIS)

Takeda, Masakado; Ushiroda, Koichi; Miyahara, Ryohei; Takano, Hiroshi; Matsuura, Tadashi; Sato, Keiya.

1998-01-01

Plant constitutional parts as targets of both of a primary pressure test and a secondary pressure test are disposed in communication with a reactor pressure vessel, and a pressure of the primary pressure test is applied to the targets of both tests, so that the primary pressure test and the second pressure test are conducted together. Since the number of pressure tests can be reduced to promote construction, and the number of workers can also be reduced. A pressure exceeding the maximum pressure upon use is applied to the pressure vessel after disposing the incore structures, to continuously conduct the primary pressure test and the secondary pressure test joined together and an incore flowing test while closing the upper lid of the pressure vessel as it is in the construction field. The number of opening/closing of the upper lid upon conducting every test can be reduced, and since the pressure resistance test is conducted after arranging circumference conditions for the incore flowing test, the tests can be conducted collectively also in view of time. (N.H.)

Dismantling institutional racism: theory and action.

Science.gov (United States)

Griffith, Derek M; Mason, Mondi; Yonas, Michael; Eng, Eugenia; Jeffries, Vanessa; Plihcik, Suzanne; Parks, Barton

2007-06-01

Despite a strong commitment to promoting social change and liberation, there are few community psychology models for creating systems change to address oppression. Given how embedded racism is in institutions such as healthcare, a significant shift in the system's policies, practices, and procedures is required to address institutional racism and create organizational and institutional change. This paper describes a systemic intervention to address racial inequities in healthcare quality called dismantling racism. The dismantling racism approach assumes healthcare disparities are the result of the intersection of a complex system (healthcare) and a complex problem (racism). Thus, dismantling racism is a systemic and systematic intervention designed to illuminate where and how to intervene in a given healthcare system to address proximal and distal factors associated with healthcare disparities. This paper describes the theory behind dismantling racism, the elements of the intervention strategy, and the strengths and limitations of this systems change approach.

Weapons dismantlement issues in independent Ukraine

International Nuclear Information System (INIS)

Zack, N.R.

1995-01-01

The American Association for the Advancement of Science sponsored a seminar during September 1993 in Kiev, Ukraine, titled, ''Toward a Nuclear-Free Future--Barriers and Problems.'' It brought together Ukrainians, Belarusians and Americans to discuss the legal, political, economic, technical, and safeguards and security dimensions of nuclear weapons dismantlement and destruction. US representatives initiated discussions on legal and treaty requirements and constraints, safeguards and security issues surrounding dismantlement, storage and disposition of nuclear materials, warhead transportation, and economic considerations. Ukrainians gave presentations on arguments for and against the Ukraine keeping nuclear weapons, the Ukrainian Parliament's nonapproval of START 1, alternative strategies for dismantling silos and launchers, and economic and security implications of nuclear weapons removal from the Ukraine. Participants from Belarus discussed proliferation and control regime issues. This paper will highlight and detail the issues, concerns and possible impacts of the Ukraine's dismantlement of its nuclear weapons

The European pressurized water reactor

International Nuclear Information System (INIS)

Leny, J.C.

1993-01-01

The present state of development of the European Pressurized Water Reactor (EPR) is outlined. During the so-called harmonization phase, the French and German utilities drew up their common requirements and evaluated the reactor concept developed until then with respect to these requirements. A main result of the harmonization phase was the issue, in September 1993, of the 'EPR Conceptual Safety Feature Review File' to be jointly assessed by the safety authorities in France and Germany. The safety objectives to be met by the EPR are specified in the second part of the paper, and some details of the primary and secondary side safety systems are given. (orig.) [de

Head spray nozzle in reactor pressure vessel

International Nuclear Information System (INIS)

Hatano, Shun-ichi.

1990-01-01

In a reactor pressure vessel of a BWR type reactor, a head spray nozzle is used for cooling the head of the pressure vessel and, in view of the thermal stresses, it is desirable that cooling is applied as uniformly as possible. A conventional head spray is constituted by combining full cone type nozzles. Since the sprayed water is flown down upon water spraying and the sprayed water in the vertical direction is overlapped, the flow rate distribution has a high sharpness to form a shape as having a maximum value near the center and it is difficult to obtain a uniform flow rate distribution in the circumferential direction. Then, in the present invention, flat nozzles each having a spray water cross section of laterally long shape, having less sharpness in the circumferential distribution upon spraying water to the inner wall of the pressure vessel and having a wide angle of water spray are combined, to make the flow rate distribution of spray water uniform in the inner wall of the pressure vessel. Accordingly, the pressure vessel can be cooled uniformly and thermal stresses upon cooling can be decreased. (N.H.)

Pumps for German pressurized water reactors

Energy Technology Data Exchange (ETDEWEB)

Dernedde, R.

1984-01-01

The article describes the development of a selection of pumps which are used in the primary coolant system and the high-pressure safety injection system and feed water system during the past 2 decades. The modifications were caused by the step-wise increasing power output of the plants from 300 MW up to 1300 MW. Additional important influences were given be the increased requirements for quality assurance and final-documentation. The good operating results of the delivered pumps proved that the reliability is independent of the volume of the software-package. The outlook expects that consolidation will be followed by additional steps for the order processing of components for the convoy pumps. KW: main coolant pump; primary system; boiler feed pump; reactor pump; secondary system; barrel insert pump; pressure water reactor; convoy pump; state of the art.

Decommissioning and dismantling of 305-M test pile at the Savannah River Plant

International Nuclear Information System (INIS)

Horton, H.L.

1985-01-01

The 305-M Test Pile was started up at the Savannah River Plant in 1952 and operated until 1981. The pile was used to measure the uranium content of reactor fuel. In 1984 work began to decommission and dismantle the pile. Extensive procedures were used that included a detailed description of the radiological controls and safety measures. These controls allowed the job to be completed with radiation doses as low as reasonably achievable

Probabilistic approach to the analysis of reactor pressure vessel integrity during a pressurized thermal shock

International Nuclear Information System (INIS)

Adamec, P.

2000-12-01

Following a general summary of the issue, an overview of international experience (USA; Belgium, France, Germany, Russia, Spain, Sweden, The Netherlands, and the UK; and probabilistic PTS assessment for the reactor pressure vessel at Loviisa-1, Finland) is presented, and the applicable computer codes (VISA-II, OCA-P, FAVOR, ZERBERUS) are highlighted and their applicability to VVER type reactor pressure vessels is outlined. (P.A.)

The pressurized water reactor

International Nuclear Information System (INIS)

Gallagher, J.L.

1987-01-01

Pressurized water reactor technology has reached a maturity that has engendered a new surge of innovation, which in turn, has led to significant advances in the technology. These advances, characterized by bold thinking but conservative execution, are resulting in nuclear plant designs which offer significant performance and safety improvements. This paper describes the innovations which are being designed into mainstream PWR technology as well as the desings which are resulting from such innovations. (author)

Pressure thermal shock analysis for nuclear reactor pressure vessel

International Nuclear Information System (INIS)

Galik, G.; Kutis, V.; Jakubec, J.; Paulech, J.; Murin, J.

2015-01-01

The appearance of structural weaknesses within the reactor pressure vessel or its structural failure caused by crack formation during pressure thermal shock processes pose as a severe environmental hazard. Coolant mixing during ECC cold water injection was simulated in a detailed CFD analysis. The temperature distribution acting on the pipe wall internal surface was calculated. Although, the results show the formation of high temperature differences and intense gradients, an additional structural analysis is required to determine the possibility of structural damage from PTS. Such an analysis will be the subject of follow-up research. (authors)

Fusion Reactor Materials

International Nuclear Information System (INIS)

Decreton, M.

2001-01-01

The objective of SCK-CEN's programme on fusion reactor materials is to contribute to the knowledge on the behaviour of fusion reactor materials and components during and after irradiation. Ongoing projects include: the study of the mechanical behaviour of structural materials under neutron irradiation; the investigation of the characteristics of irradiated first wall material such as beryllium; the detection of abrupt electrical degradation of insulating ceramics under high temperature and neutron irradiation; and the study of dismantling and waste disposal strategy for fusion reactors. Progress and achievements in these areas in 2000 are discussed

Technological status of reactor coolant pumps in generation III+ pressurized nuclear reactors

Energy Technology Data Exchange (ETDEWEB)

Brecht, Bernhard; Bross, Stephan [KSB Aktiengesellschaft, Frankenthal (Germany)

2016-05-15

KSB has been developing and producing pumps for thermal power plants for nearly 90 years. Consequently, KSB also started to develop and manufacture pumps for all kinds of nuclear power plants from the very beginning of the civil use of nuclear energy. This is especially true for reactor coolant pumps for pressurized water reactors. For the generation of advanced evolutionary reactors (Generation III+ reactors), KSB developed an advanced shaft seal system which is also able to fulfill the requirements of station blackout conditions. The tests in the KSB test rigs, which were successfully completed in December 2015, proved the full functionality of the new design. For generation III+ passive plant reactors KSB developed a new reactor coolant pump type called RUV, which is based on the experience of classic reactor coolant pumps and reactor internal pumps. It is a very compact, hermetically sealed vertical pump-motor unit with a wet winding motor. A full scale prototype successfully passed the 1st stage qualification test program in October 2015.

Implementation of the environmental management plan for the dismantling of nuclear powered submarines at Zvezdochka Shipyard, Russia

International Nuclear Information System (INIS)

Washer, M.; Cull, M.; Crocker, C.; Ivanov, V.; Shepurev, A.; Khan, B.U.Z.; Lee, M.; Gerchikov, M.

2007-01-01

Department of Foreign Affairs and International Trade Canada is funding the dismantling of twelve nuclear powered submarines (NPS) from the Russian Federation's Northern Fleet as part of the Global Partnership Initiative against weapons and materials of mass destruction. In this paper, work performed by Nuclear Safety Solutions Ltd. and its collaborators in support of these activities is described. First, an environmental impact assessment of towing and dismantling NPS in the Kola Peninsula, and the Barents and White Seas was performed. The assessed activities included: towing of NPS from Naval Bases in Murmansk Region to the Zvezdochka shipyard (Severodvinsk); defuelling of onboard reactors; dismantling of NPS at Zvezdochka; and waste management. The assessment helped identify mitigation measures that could prevent the occurrence of adverse effects. Next, the project team defined and implemented an environmental management plan (EMP) based on the shipyard's existing environmental policy and the mitigating measures identified during the environmental assessment. Specific targets were defined to track the progress of the EMP implementation, and are described in this paper. During the study period, three Victor Class NPS were dismantled at Zvezdochka. The major benefits realized include: removal and spent nuclear fuel assemblies; treatment/decontamination of liquid and solid radioactive waste; and the cultivation of collaboration between Russian and Western expertise. (author)

Implementation of the environmental management plan for the dismantling of nuclear powered submarines at Zvezdochka shipyard, Russia

International Nuclear Information System (INIS)

Washer, M.; Cull, M.; Crocker, C.; Ivanov, V.; Shepurev, A.; Khan, B.U.Z.; Lee, M.; Gerchikov, M.

2008-01-01

Department of Foreign Affairs and International Trade Canada is funding the dismantling of twelve nuclear powered submarines (NPS) from the Russian Federation's Northern Fleet as part of the Global Partnership Initiative against weapons and materials of mass destruction. In this paper, work performed by Nuclear Safety Solutions Ltd. and its collaborators in support of these activities is described. First, an environmental impact assessment of towing and dismantling NPS in the Kola Peninsula, and the Barents and White Seas was performed. The assessed activities included: towing of NPS from Naval Bases in Murmansk Region to the Zvezdochka shipyard (Severodvinsk); defuelling of onboard reactors; dismantling of NPS at Zvezdochka; and waste management. The assessment helped identify mitigation measures that could prevent the occurrence of adverse effects. Next, the project team defined and implemented an environmental management plan (EMP) based on the shipyard's existing environmental policy and the mitigating measures identified during the environmental assessment. Specific targets were defined to track the progress of the EMP implementation, and are described in this paper. During the study period, three Victor Class NPS were dismantled at Zvezdochka. The major benefits realized include: removal of spent nuclear fuel assemblies; treatment/ decontamination of liquid and solid radioactive waste; and the cultivation of collaboration between Russian and Western expertise. (author)

Plastic reactor suitable for high pressure and supercritical fluid electrochemistry

DEFF Research Database (Denmark)

Branch, Jack; Alibouri, Mehrdad; Cook, David A.

2017-01-01

The paper describes a reactor suitable for high pressure, particularly supercritical fluid, electrochemistry and electrodeposition at pressures up to 30 MPa at 115◦C. The reactor incorporates two key, new design concepts; a plastic reactor vessel and the use of o-ring sealed brittle electrodes...... by the deposition of Bi. The application of the reactor to the production of nanostructures is demonstrated by the electrodeposition of ∼80 nm diameter Te nanowires into an anodic alumina on silicon template. Key advantages of the new reactor design include reduction of the number of wetted materials, particularly...... glues used for insulating electrodes, compatability with reagents incompatible with steel, compatability with microfabricated planar multiple electrodes, small volume which brings safety advantages and reduced reagent useage, and a significant reduction in experimental time....

Analysis code for pressure in reactor containment vessel of ATR. CONPOL

International Nuclear Information System (INIS)

1997-08-01

For the evaluation of the pressure and temperature in containment vessels in the events which are classified in the abnormal change of pressure, atmosphere and others in reactor containment vessels in accident among the safety evaluation events of the ATR, the analysis code for the pressure in reactor containment vessels CONPOL is used. In this report, the functions of the analysis code and the analysis model are shown. By using this analysis code, the rise of the pressure and temperature in a containment vessel is evaluated when loss of coolant accident occurs, and high temperature, high pressure coolant flows into it. This code possesses the functions of computing blow-down quantity and heat dissipation from reactor cooling facility, steam condensing heat transfer to containment vessel walls, and the cooling effect by containment vessel spray system. As for the analysis techniques, the models of reactor cooling system, containment vessel and steam discharge pool, and the computation models for the pressure and temperature in containment vessels, wall surface temperature, condensing heat transfer, spray condensation and blow-down are explained. The experimental analysis of the evaluation of the pressure and temperature in containment vessels at the time of loss of coolant accident is reported. (K.I.)

Plant life management strategies for pressurized heavy water reactors

Energy Technology Data Exchange (ETDEWEB)

Kim, Young Suk; Kwon, Sang Chul; Choo, Ki Nam; Ahn, Sang Bok; Kuk, Il Hyun [Korea Atomic Energy Research Institute, Taejon (Korea)

1998-06-01

This technical report reviewed aging mechanism of the major components of CANDU 6 reactor such as pressure tubes, calandria tube, end fitting, fuel channel spacer and calandria. Furthermore, the surveillance methodology was described for monitoring and inspection of these core components. Based on the in-reactor performances data such as delayed hydride cracking, leak-before-break, enhanced deformation-creep and growth, the life management of pressure tubes was illustrated in this report. (author). 19 refs., 11 figs., 2 tabs.

Development and design of control rod drive mechanisms for pressurized water reactors

International Nuclear Information System (INIS)

Leme, Francisco Louzano

2003-01-01

The Control Rod Drive Mechanisms (CRDM) for a Pressurized Water Reactor (PWR) are equipment, integrated to the reactor pressure vessel, incorporating mechanical and electrical components designed to move and position the control rods to guarantee the control of power and shutdown of the nuclear reactor, during normal operation, either in emergency or accidental situations. The type of CRDM used in PWR reactors, whose detailed individual description will be presented in this monograph are the Roller-Nut and Magnetic-Jack. The environment, where the CRDM performs its above presented operational functions, includes direct contact with the fluid used as coolant peculiar to the interior of the reactor, and its associated chemical characteristics, the radiation field next to the reactor core, and also the temperature and pressure in the reactor pressure vessel. So the importance of the CRDM design requirements related to its safety functions are emphasized. Finally, some aspects related to the mechanical and structural design of CRDM of a case study, considering the CRDM for a PWR from the experimental nuclear plant to be applied by CTMSP (Centro Tecnologico da Marinha em Sao Paulo), are pointed out. The design and development of these equipment (author)

Fabrication of mixed oxide fuel using plutonium from dismantled weapons

International Nuclear Information System (INIS)

Blair, H.T.; Chidester, K.; Ramsey, K.B.

1996-01-01

A very brief summary is presented of experimental studies performed to support the use of plutonium from dismantled weapons in fabricating mixed oxide (MOX) fuel for commercial power reactors. Thermal treatment tests were performed on plutonium dioxide powder to determine if an effective dry gallium removal process could be devised. Fabrication tests were performed to determine the effects of various processing parameters on pellet quality. Thermal tests results showed that the final gallium content is highly dependent on the treatment temperature. Fabrication tests showed that the milling process, sintering parameters, and uranium feed did effect pellet properties. 1 ref., 1 tab

The safety of pressurized water reactors

International Nuclear Information System (INIS)

Panossian, J.; Tanguy, P.

1991-01-01

In this paper we present a review of the status of the safety level of modern pressurized water reactors, that is to say those that meet the safety criteria accepted today by the international nuclear community. We will mainly rely on the operating experience and the Probabilistic Safety Assessments concerning French reactors. We will not back over the basic safety concepts of these reactors, which are well known. We begin with a brief review of some of the lessons learned from the two main accidents discussed in the present meeting. Three Mile Island and Chernobyl, without entering into details presented in previous papers. The presentation ends with a rather lengthy conclusion, aimed more at those not directly involved in the technical details of nuclear safety matters

Installation dismantling system, working process and hood utilizable in this system

International Nuclear Information System (INIS)

Poirier, J.C.; Mulcey, P.; Morel, P.; Vavasseur, C.

1989-01-01

The system for dismantling an installation under a controlled atmosphere is made by a tool polluting the atmosphere, a gas blanket creating a continement zone around the tool, an extractor removing polluted gas from the zone, a purifier for the extracted gas and a controller regulating the flow of gas in the blanket and keeping the installation at constant pressure [fr

Decontamination and dismantling at the CEA

International Nuclear Information System (INIS)

2006-01-01

This document presents the dismantling policy at the CEA (French Research Center on the atomic energy), the financing of the decontamination and the dismantling, the regulatory framework, the knowledge and the technology developed at the CEA, the radiation protection, the environment monitoring and the installations. (A.L.B.)

Advanced Approach of Reactor Pressure Vessel In-service Inspection

International Nuclear Information System (INIS)

Matokovic, A.; Picek, E.; Pajnic, M.

2006-01-01

The most important task of every utility operating a nuclear power plant is the continuously keeping of the desired safety and reliability level. This is achieved by the performance of numerous inspections of the components, equipment and system of the nuclear power plant in operation and in particular during the scheduled maintenance periods at re-fueling time. Periodic non-destructive in-service inspections provide most relevant criteria of the integrity of primary circuit pressure components. The task is to reliably detect defects and realistically size and characterize them. One of most important and the most extensive examination is a reactor pressure vessel in-service inspection. That inspection demand high standards of technology and quality and continual innovation in the field of non-destructive testing (NDT) advanced technology as well as regarding reactor pressure vessel tool and control systems. A remote underwater contact ultrasonic technique is employed for the examination of the defined sections (reactor welds), whence eddy current method is applied for clad surface examinations. Visual inspection is used for examination of the vessel inner surface. The movement of probes and data positioning are assured by using new reactor pressure vessel tool concept that is fully integrated with NDT systems. The successful performance is attributed thorough pre-outage planning, training and successful performance demonstration qualification of chosen NDT techniques on the specimens with artificial and/or real defects. Furthermore, use of advanced approach of inspection through implementation the state of the art examination equipment significantly reduced the inspection time, radiation exposure to examination personnel, shortening nuclear power plant outage and cutting the total inspection costs. The advanced approach as presented in this paper offer more flexibility of application (non-destructive tests, local grinding action as well as taking of boat samples

Reactor Pressure Vessel Steels

Energy Technology Data Exchange (ETDEWEB)

Van de Velde, J.; Fabry, A.; Van Walle, E.; Chaoudi, R

1998-07-01

SCK-CEN's R and D programme on Reactor Pressure Vessel (RPV) Steels in performed in support of the RVP integrity assessment. Its main objectives are: (1) to develop enhanced surveillance concepts by applying micromechanics and fracture-toughness tests to small specimens, and by performing damage modelling and microstructure characterization; (2) to demonstrate the applied methodology on a broad database; (3) to achieve regulatory acceptance and industrial use. Progress and achievements in 1999 are reported.

Radiation embrittlement in pressure vessels of power reactors

International Nuclear Information System (INIS)

Kempf, Rodolfo; Fortis, Ana M.

2007-01-01

It is presented the project to study the effect of lead factors on the mechanical behavior of Reactor Pressure Vessel steels. It is described the facility designed to irradiate Charpy specimens with V notch of SA-508 type 3 steel at power reactor temperature, installed in the RA-1 reactor. The objective is to obtain the fracture behavior of irradiated specimens with different lead factors and to know their dependence with the diffusion of alloy elements. (author) [es

Definition of a dismantling project

International Nuclear Information System (INIS)

Meyers, H.; Claes, J.; Geens, L.

1988-01-01

The shutdown of the fuel reprocessing plant of Eurochemic having been decided, a study for defining the facilities to be dismantled and how to do it, was conducted by Belgoprocess. The cost of the operation was estimated by an accurate investigation and by a pilot project on the dismantling of the wastes storage building. The work carried out up to now and the problems to be solved are summarized [fr

A reactor for high-throughput high-pressure nuclear magnetic resonance spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Beach, N. J.; Knapp, S. M. M.; Landis, C. R., E-mail: landis@chem.wisc.edu [Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53719 (United States)

2015-10-15

The design of a reactor for operando nuclear magnetic resonance (NMR) monitoring of high-pressure gas-liquid reactions is described. The Wisconsin High Pressure NMR Reactor (WiHP-NMRR) design comprises four modules: a sapphire NMR tube with titanium tube holder rated for pressures as high as 1000 psig (68 atm) and temperatures ranging from −90 to 90 °C, a gas circulation system that maintains equilibrium concentrations of dissolved gases during gas-consuming or gas-releasing reactions, a liquid injection apparatus that is capable of adding measured amounts of solutions to the reactor under high pressure conditions, and a rapid wash system that enables the reactor to be cleaned without removal from the NMR instrument. The WiHP-NMRR is compatible with commercial 10 mm NMR probes. Reactions performed in the WiHP-NMRR yield high quality, information-rich, and multinuclear NMR data over the entire reaction time course with rapid experimental turnaround.

The extension of the SWS period or CANDU reactors with particular reference to Douglas Point

International Nuclear Information System (INIS)

Bennett, C.R.

1985-01-01

The foregoing approach to the determination of the fate of a concrete containment building is worth much consideration. The expenditure of $10 8 or its escalated equivalent is too much to pay for the probable saving of fraction of a statistical life. The unquestioning adoption of the dogma of reactor dismantlement displays a complete misunderstanding of the numerics of ''risk'', even the place of reactor dismantling in the spectrum of nuclear risk. The position of the risk of reactor dismantling is more than an order of magnitude lower than the former of these. The most altruistic criterion for any engineering activity is the achievement of the greatest expected net benefit (or the least expected net detriment) when all the consequences of the activity are taken into account. As has been shown this criterion leads to the conclusion that, at least in CANDU reactors and particularly Douglas Point, there is apparently no reason why the S.W.S. period should not be extended indefinitely

Pressure vessel codes: Their application to nuclear reactor systems

International Nuclear Information System (INIS)

1966-01-01

A survey has been made by the International Atomic Energy Agency of how the problems of applying national pressure vessel codes to nuclear reactor systems have been treated in those Member States that had pressurized reactors in operation or under construction at the beginning of 1963. Fifteen answers received to an official inquiry form the basis of this report, which also takes into account some recently published material. Although the answers to the inquiry in some cases data back to 1963 and also reflect the difficulty of describing local situations in answer to standard questions, it is hoped that the report will be of interest to reactor engineers. 21 refs, 1 fig., 2 tabs

SCW Pressure-Channel Nuclear Reactors: Some Design Features and Concepts

International Nuclear Information System (INIS)

Duffey, R.B.; Pioro, I.L.; Gabaraev, B.A.; Kuznetsov, Yu. N.

2006-01-01

Concepts of nuclear reactors cooled with water at supercritical pressures were studied as early as the 1950's and 1960's in the USA and Russia. After a 30-year break, the idea of developing nuclear reactors cooled with supercritical water (SCW) became attractive again as the ultimate development path for water-cooling. The main objectives of using SCW in nuclear reactors are 1) to increase the thermal efficiency of modern nuclear power plants (NPPs) from 33 -- 35% to about 40 -- 45%, and 2) to decrease capital and operational costs and hence decrease electrical energy costs (∼$ 1000 US/kW). SCW NPPs will have much higher operating parameters compared to modern NPPs (pressure about 25 MPa and outlet temperature up to 625 deg. C), and a simplified flow circuit, in which steam generators, steam dryers, steam separators, etc., can be eliminated. Also, higher SCW temperatures allow direct thermo-chemical production of hydrogen at low cost, due to increased reaction rates. Pressure-channel SCW nuclear reactor concepts are being developed in Canada and Russia. Design features related to both channels and fuel bundles are discussed in this paper. Also, Russian experience with operating supercritical steam heaters at NPP is presented. The main conclusion is that development of SCW pressure-channel nuclear reactors is feasible and significant benefits can be expected over other thermal energy systems. (authors)

Management of wastes from dismantled nuclear power plants

International Nuclear Information System (INIS)

1979-01-01

The problems associated with the management of radioactive wastes encountered in the dismantling of a 1200MWe PWR reactor are considered. It is possible to extend all the conclusions reached in these studies to BWR's or other reactors of the same type using light water as a coolant and moderator. The studies performed established the specific characteristics of these wastes: a gamma activity due essentially to 60 Co (after some fifty years this radioisotope will have decayed sufficiently to enable it to be stored without shielding); the presence of 63 Ni and 59 Ni (these long half-life beta emitting radioisotopes need to be stored over a long or even indefinite period of time); contaminated components (60% of the overall wastes), the reselling of these components involving costly decontamination processes. Extensive studies have been conducted on the management and handling of these wastes: packaging, transport, processing, storage and a great many techniques have been developed. However, further developments in concentration methods (fusion, crushing, cryogenics etc) and the selection of storage sites for this type of waste are necessary. Depending on the solutions chosen, the global cost of the wastes coming from a 1200 MW PWR reactor can vary between 10 and 20 million BFR

Fusion Reactor Materials

International Nuclear Information System (INIS)

Decreton, M.

2002-01-01

The objective of SCK-CEN's programme on fusion reactor materials is to contribute to the knowledge on the radiation-induced behaviour of fusion reactor materials and components as well as to help the international community in building the scientific and technical basis needed for the construction of the future reactor. Ongoing projects include: the study of the mechanical and chemical (corrosion) behaviour of structural materials under neutron irradiation and water coolant environment; the investigation of the characteristics of irradiated first wall material such as beryllium; investigations on the management of materials resulting from the dismantling of fusion reactors including waste disposal. Progress and achievements in these areas in 2001 are discussed

Welding of the A1 reactor pressure vessel

International Nuclear Information System (INIS)

Becka, J.

1975-01-01

As concerns welding, the A-1 reactor pressure vessel represents a geometrically complex unit containing 1492 welded joints. The length of welded sections varies between 10 and 620 mm. At an operating temperature of 120 degC and a pressure of 650 N/cm 2 the welded joints in the reactor core are exposed to an integral dose of 3x10 18 n/cm 2 . The chemical composition is shown for pressure vessel steel as specified by CSN 413090.9 modified by Ni, Ti and Al additions, and for the welding electrodes used. The requirements are also shown for the mechanical properties of the base and the weld metals. The technique and conditions of welding are described. No defects were found in ultrasonic testing of welded joints. (J.B.)

Behavior of a corium jet in high pressure melt ejection from a reactor pressure vessel

International Nuclear Information System (INIS)

Frid, W.

1988-04-01

Discharge of the molten core debris from a pressurized reactor vessel has been recognized as an important accident scenario for pressurized water reactors. Recent high-pressure melt streaming experiments conducted at Sandia National Laboratories, designed to study cavity and containment events related to melt ejection, have resulted in two important observations: (1) Expansion and breakup of the ejected molten jet. (2) Significant aerosol generation during the ejection process. The expansion and breakup of the jet in the experiments are attributed to rapid evolution of the pressurizing gas (nitrogen or hydrogen) dissolved in the melt. It has been concluded that aerosol particles may be formed by condensation of melt vapor and mechanical breakup of the melt and generation. It was also shown that the above stated phenomena are likely to occur in reactor accidents. This report provides results from analytical and experimental investigations on the behavior of a gas supersaturated molten jet expelled from a pressurized vessel. Aero-hydrodynamic stability of liquid jets in gas, stream degassing of molten metals, and gas bubble nucleation in molten metals are relevant problems that are addressed in this work

A quantitative methodology for reactor vessel pressurized thermal shock decision making

International Nuclear Information System (INIS)

Ackerson, D.S.; Balkey, K.R.; Meyer, T.A.; Ofstun, R.P.; Rupprecht, S.D.; Sharp, D.R.

1983-01-01

The recent operating experience of the Pressurized Water Reactor (PWR) Industry has focused increasing attention on the issue of reactor vessel pressurized thermal shock (PTS). Previous reactor vessel integrity concerns have led to changes in vessel and plant system design and to operating procedures, and increased attention to the PTS issue is causing consideration of further modifications. Events such as excess feedwater, loss of normal feedwater, and steam generator tube rupture have led to significant primary system cooldowns. Each of these cooldown transients occurred concurrently with a relatively high primary system pressure. Considerations of these and other postulated cooldown events has drawn attention to the impact of operator action and control system effects on reactor vessel PTS. A methodology, which couples event sequence analysis with probabilistic fracture mechanics analyses, was developed to identify those events that are of primary concern for reactor vessel integrity. Operating experience is utilized to aid in defining the appropriate event sequences and event frequencies of occurrence for the evaluation. (orig./RW)

Decontamination and recycle of zirconium pressure tubes from Pressurized Heavy Water Reactor

International Nuclear Information System (INIS)

Gantayet, L.M.; Verma, R.; Remya Devi, P.S.; Banerjee, S.; Kotak, V.; Raha, A.; Sandeep, K.C.; Joshi, Shreeram W.; Lali, A.M.

2009-01-01

An ion exchange process has been developed for decontamination of zirconium pressure tubes from Pressurized Heavy Water Reactor and recycling of neutronically improved zirconium. Distribution coefficient, equilibrium isotherm, kinetic and breakthrough data were used to develop the separation process. Effect of gamma radiation on indigenous resins was also studied to assess their suitability in high radiation field. (author)

BRET fuel assembly dismantling machine

International Nuclear Information System (INIS)

Titzler, P.A.; Bennett, K.L.; Kelley, R.S. Jr.; Stringer, J.L.

1984-08-01

An automated remote nuclear fuel assembly milling and dismantling machine has been designed, developed, and demonstrated at the Hanford Engineering Development Laboratory (HEDL) in Richland, Washington. The machine can be used to dismantle irradiated breeder fuel assemblies from the Fast Flux Test Facility prior to fuel reprocessing. It can be installed in an existing remotely operated shielded hot cell facility, the Fuels and Materials Examination Facility (FMEF), at the Hanford Site in Richland, Washington

Nuclear reactor of pressurized liquid coolant type

International Nuclear Information System (INIS)

Costes, D.

1976-01-01

The reactor comprises a vertical concrete pressure vessel, a bell-housing having an open lower end and disposed coaxially with the interior of the pressure vessel so as to delimit therewith a space filled with gas under pressure for the thermal insulation of the internal vessel wall, a pressurizing device for putting the coolant under pressure within the bell-housing and comprising a volume of control gas in contact with a large free surface of coolant in order that an appreciable variation in volume of liquid displaced within the coolant circuit inside the bell-housing should correspond to a small variation in pressure of the control gas. 9 claims, 3 drawing figures

Comparison of thorough decontamination techniques on dismantled pieces of a PWR reactor

International Nuclear Information System (INIS)

Klein, M.; Rahier, A.; Mandoki, R.; Ponnet, M.

1998-01-01

The decontamination experience gained during the BR3 dismantling project is developed. This started with the full system decontamination of the primary loop and was followed by R and D on thorough decontamination projects. First, a wet abrasive installation has been installed and is now in operation for the thorough cleaning of metallic pieces of simple geometry. Afterwards, the chemical cerium process has been developed. The results of the regeneration with ozone and with electrochemistry are presented in detail. The ozone regeneration process has been selected for the industrial installation of which the construction is foreseen in 1998. (author)

Design of virtual SCADA simulation system for pressurized water reactor

International Nuclear Information System (INIS)

Wijaksono, Umar; Abdullah, Ade Gafar; Hakim, Dadang Lukman

2016-01-01

The Virtual SCADA system is a software-based Human-Machine Interface that can visualize the process of a plant. This paper described the results of the virtual SCADA system design that aims to recognize the principle of the Nuclear Power Plant type Pressurized Water Reactor. This simulation uses technical data of the Nuclear Power Plant Unit Olkiluoto 3 in Finland. This device was developed using Wonderware Intouch, which is equipped with manual books for each component, animation links, alarm systems, real time and historical trending, and security system. The results showed that in general this device can demonstrate clearly the principles of energy flow and energy conversion processes in Pressurized Water Reactors. This virtual SCADA simulation system can be used as instructional media to recognize the principle of Pressurized Water Reactor

Design of virtual SCADA simulation system for pressurized water reactor

Energy Technology Data Exchange (ETDEWEB)

Wijaksono, Umar, E-mail: umar.wijaksono@student.upi.edu; Abdullah, Ade Gafar; Hakim, Dadang Lukman [Electrical Power System Research Group, Department of Electrical Engineering Education, Jl. Dr. Setiabudi No. 207 Bandung, Indonesia 40154 (Indonesia)

2016-02-08

The Virtual SCADA system is a software-based Human-Machine Interface that can visualize the process of a plant. This paper described the results of the virtual SCADA system design that aims to recognize the principle of the Nuclear Power Plant type Pressurized Water Reactor. This simulation uses technical data of the Nuclear Power Plant Unit Olkiluoto 3 in Finland. This device was developed using Wonderware Intouch, which is equipped with manual books for each component, animation links, alarm systems, real time and historical trending, and security system. The results showed that in general this device can demonstrate clearly the principles of energy flow and energy conversion processes in Pressurized Water Reactors. This virtual SCADA simulation system can be used as instructional media to recognize the principle of Pressurized Water Reactor.

Coolant mixing in pressurized water reactors

Energy Technology Data Exchange (ETDEWEB)

Hoehne, T; Grunwald, G

1998-10-01

The behavior of PWRs during cold water or boron dilution transients is strongly influenced by the distribution of coolant temperature and boron concentration at the core inlet. This distribution is the needed input to 3-dimensional neutron kinetics to calculate the power distribution in the core. It mainly depends on how the plugs of cold or unborated water formed in a single loop are mixed in the downcomer and in the lower plenum. To simulate such mixture phenomena requires the application of 3-dimensional CFD (computational fluid dynamics) codes. The results of the simulation have to be validated against mixture experiments at scaled facilities. Therefore, in the framework of a research project funded by BMBF, the institute creates a 1:5 mixture facility representing first the geometry of a German pressurized water reactor and later the European Pressurized Water Reactor (EPR) geometry. The calculations are based on the CFD Code CFX-4. (orig.)

Problems in manufacturing and transport of pressure vessels of integral reactors

International Nuclear Information System (INIS)

Kralovec, J.

1997-01-01

Integral water-cooled reactors are typical with eliminating large-diameter primary pipes and placing primary components, i.e. steam generators and pressurizers in reactor vessels. This arrangement leads to reactor pressure vessels of large dimensions: diameters, heights and thick walls and subsequently to great weights. Thus, even medium power units have pressure vessels which are on the very limit of present manufacturing capabilities. Principal manufacturing and inspection operations as well as pertinent equipment are concerned: welding, cladding, heat treatment, machining, shop-handling, non-destructive testing, hydraulic pressure tests etc. Tile transport of such a large and heavy component makes a problem which effects its design as well as the selection of the plant site. Railway, road and ship are possible ways of transport each of them having its advantages and limitations. Specific features and limits of the manufacture and transport of large pressure vessels are discussed in the paper. (author)

Flooding of a large, passive, pressure-tube light water reactor

International Nuclear Information System (INIS)

Hejzlar, P.; Todreas, N.E.; Driscoll, M.J.

1997-01-01

A reactor concept has been developed which can survive loss of coolant accidents without scram and without replenishing primary coolant inventory, while maintaining safe temperature limits on the fuel and pressure tubes. The proposed concept is a pressure tube type reactor of similar design to CANDU reactors, but differing in three key aspects. First, a solid SiC-coated graphite fuel matrix is used in place of fuel pin bundles to enable the dissipation of decay heat from the fuel in the absence of primary coolant. Second, the heavy water coolant in the pressure tubes is replaced by light water, which also serves as the moderator. Finally, the calandria tank, surrounded by a graphite reflector, contains a low pressure gas instead of heavy water moderator, and this normally-voided calandria is connected to a light water heat sink. The cover gas displaces the light water from the calandria during normal operation, while during loss of coolant or loss of heat sink accidents it allows passive calandria flooding. Calandria flooding also provides redundant and diverse reactor shutdown. This paper describes the thermal hydraulic characteristics of the passively initiated, gravity driven calandria flooding process. Flooding the calandria space with light water is a unique and very important feature of the proposed pressure-tube light water reactor (PTLWR) concept. The flooding of the top row of fuel channels must be accomplished fast enough so that in the total loss of coolant, none of the critical components of the fuel channel, i.e. the pressure tube, the calandria tube, the matrix and the fuel, exceed their design limits. The flooding process has been modeled and shown to be rapid enough to maintain all components within their design limits. (orig.)

Evaluation of hydride blisters in zirconium pressure tube in CANDU reactor

International Nuclear Information System (INIS)

Cheong, Y. M.; Kim, Y. S.; Gong, U. S.; Kwon, S. C.; Kim, S. S.; Choo, K.N.

2000-09-01

When the garter springs for maintaining the gap between the pressure tube and the calandria tube are displaced in the CANDU reactor, the sagging of pressure tube results in a contact to the calandria tube. This causes a temperature difference between the inner and outer surface of the pressure tube. The hydride can be formed at the cold spot of outer surface and the volume expansion by hydride dormation causes the blistering in the zirconium alloys. An incident of pressure tube rupture due to the hydride blisters had happened in the Canadian CANDU reactor. This report describes the theoretical development and models on the formation and growth of hydride blister and some experimental results. The evaluation methodology and non-destructive testing for hydride blister in operating reactors are also described

Evaluation of hydride blisters in zirconium pressure tube in CANDU reactor

Energy Technology Data Exchange (ETDEWEB)

Cheong, Y M; Kim, Y S; Gong, U S; Kwon, S C; Kim, S S; Choo, K N

2000-09-01

When the garter springs for maintaining the gap between the pressure tube and the calandria tube are displaced in the CANDU reactor, the sagging of pressure tube results in a contact to the calandria tube. This causes a temperature difference between the inner and outer surface of the pressure tube. The hydride can be formed at the cold spot of outer surface and the volume expansion by hydride dormation causes the blistering in the zirconium alloys. An incident of pressure tube rupture due to the hydride blisters had happened in the Canadian CANDU reactor. This report describes the theoretical development and models on the formation and growth of hydride blister and some experimental results. The evaluation methodology and non-destructive testing for hydride blister in operating reactors are also described.

Rupture tests with reactor pressure vessel head models

International Nuclear Information System (INIS)

Talja, H.; Keinaenen, H.; Hosio, E.; Pankakoski, P.H.; Rahka, K.

2003-01-01

In the LISSAC project (LImit Strains in Severe ACcidents), partly funded by the EC Nuclear Fission and Safety Programme within the 5th Framework programme, an extensive experimental and computational research programme is conducted to study the stress state and size dependence of ultimate failure strains. The results are aimed especially to make the assessment of severe accident cases more realistic. For the experiments in the LISSAC project a block of material of the German Biblis C reactor pressure vessel was available. As part of the project, eight reactor pressure vessel head models from this material (22 NiMoCr 3 7) were tested up to rupture at VTT. The specimens were provided by Forschungszentrum Karlsruhe (FzK). These tests were performed under quasistatic pressure load at room temperature. Two specimens sizes were tested and in half of the tests the specimens contain holes describing the control rod penetrations of an actual reactor pressure vessel head. These specimens were equipped with an aluminium liner. All six tests with the smaller specimen size were conducted successfully. In the test with the large specimen with holes, the behaviour of the aluminium liner material proved to differ from those of the smaller ones. As a consequence the experiment ended at the failure of the liner. The specimen without holes yielded results that were in very good agreement with those from the small specimens. (author)

Development of alternative fuel for pressurized water reactors

International Nuclear Information System (INIS)

Cardoso, P.E.; Ferreira, R.A.N.; Ferraz, W.B.; Lameiras, F.S.; Santos, A.; Assis, G. de; Doerr, W.O.; Wehner, E.L.

1984-01-01

The utilization of alternative fuel cycles in Pressurized Water Reactors (PWR) such as Th/U and Th/Pu cycles can permit a better utilization of uranium reserves without the necessity of developing new power reactor concepts. The development of the technology of alternative fuels for PWR is one of the objectives of the 'Program on Thorium Utilization in Pressurized Water Reactors' carried out jointly by Empresas Nucleares Brasileiras S.A. (NUCLEBRAS), through its Centro de Desenvolvimento da Tecnologia Nuclear (CDTN) and by German institutions, the Julich Nuclear Research Center (KFA), the Kraftwerk Union A.G. (KWU) and NUKEM GmbH. This paper summarizes the results so far obtained in the fuel technology. The development of a fabrication process for PWR fuel pellets from gel-microspheres is reported as well as the design, the specification, and the fabrication of prototype fuel rods for irradiation tests. (Author) [pt

Dismantling and waste managing benefit from digital technologies

International Nuclear Information System (INIS)

Moitrier, C.

2017-01-01

Dismantling is a very important challenge for nuclear industry as its success will prove the ability of the industry to deal with all the stages of a nuclear power plant from design to the end. A dismantling project is constraint by costs, time, feasibility, safety and environment protection and all of this implies a perfect knowledge of both the initial state of the facility at the beginning of the dismantling and the supply chain to avoid delays and extra-costs. Digital tools have a very important role to play as a provider of a 3-dimensional digital twin of the facility. This digital model allows: a remote preparation of the dismantling actions, to assess and optimize the radiation exposure during the intervention, to simulate various scenarios and select the most adequate, to ease collaborative work between various teams, to assess the volume and kind of waste at a very early stage of the dismantling, and to train operators and workers for x. (A.C.)

Preservation of the first research nuclear reactor in Korea

International Nuclear Information System (INIS)

2008-06-01

This book describes preservation of the first research nuclear reactor in Korea and necessity of building memorial hall, sale of the Institute of Atomic Energy Research in Seoul and dismantlement of the first and the second nuclear reactor, preservation of the first research nuclear reactor and activity about memorial hall of the atomic energy reactor, assignment and leaving the report, and the list of related data.

Leak detection device for nuclear reactor pressure vessel

International Nuclear Information System (INIS)

Ikeda, Jun.

1988-01-01

Purpose: To test the leakage of a nuclear reactor pressure vessel during stopping for a short period of time with no change to the pressure vessel itself. Constitution: The device of the present invention comprises two O-rings disposed on the flange surface that connects a pressure vessel main body and an upper cover, a leak-off pipeway derived from the gap of the O-rings at the flange surface to the outside of the pressure vessel, a pressure detection means connected to the end of the pipeway, a humidity detection means disposed to the lead-off pipeway, a humidity detection means disposed to the lead-off pipeway, and gas supply means and gas suction means disposed each by way of a check valve to a side pipe branched from the pipeway. After stopping the operation of the nuclear reactor and pressurizing the pressure vessel by filling water, gases supplied to the gap between the O-rings at the flange surface by opening the check valve. In a case where water in the pressure vessel should leak to the flange surface, when gas suction is applied by properly opening the check valve, increase in the humidity due to the steams of leaked water diffused into the gas is detected to recognize the occurrence of leakage. (Kamimura, M.)

Superheated steam annealing of pressurized water reactor vessel

International Nuclear Information System (INIS)

Porowski, J.S.

1993-01-01

Thermal annealing of an embrittled Reactor Pressure Shell is the only recognized means for recovering material properties lost due to long-term exposure of the reactor walls to radiation. Reduced toughness of the material during operation is a major concern in evaluations of structural integrity of older reactors. Extensive studies performed within programs related to life extension of nuclear plants have confirmed that the thermal treatment of 850 deg. F for 168 hours on irradiated material essentially recovers material properties lost due to neutron exposure. Dry and wet annealing methods have been considered. Wet annealing involves operating the reactor at near design temperatures and pressures. Since the temperature of wet annealing must be limited to vessel design temperature of 650 deg. F, only partial recovery of the lost properties is achieved. Thus dry annealing was selected as an alternative for future development and industrial implementation to extend the safe life of reactors. Dry thermal annealing consists of heating portions of the reactor vessel at a specific temperature for a given period of time using a high temperature heat source. The use of spent fuel assemblies, induction heating and resistance heating elements as well as the circulation of heated fluid were investigated as potential candidate methods. To date the use of resistance heating elements which are lowered into a dry empty reactor was considered to be the preferred method. In-depth research in the United States and practical applications of such a method in Russia have confirmed feasibility of the method. The method of using circulating superheated steam to anneal the vessel at 850 deg. F without complete removal of the reactor internals is described herein. After removing the reactor head and fuel, the core barrel along with the upper and lower core in PWRs is lifted to open an annular space between the reactor shell flange and the core barrel flange. The thermal shield can remain

Acoustic Emission for on-line reactor pressure boundary monitoring

International Nuclear Information System (INIS)

Hutton, P.H.; Kurtz, R.J.; Pappas, R.A.

1985-01-01

The program objective is to develop AE for continuous surveillance to assess flaw growth in reactor pressure boundaries. Technology in the laboratory is being evaluated on structures. Results have demonstrated basic feasibility of the program objective. AE monitoring a long term fatigue test of a pressure vessel demonstrated an instrument system, and the ability to detect unexpected as well as well as known fatigue cracks. Monitoring a nuclear reactor system shows that the coolant flow noise problem is manageable and AE can be detected under simulated operating conditions

Basic conceptions for reactor pressure vessel manipulators and their evaluation

International Nuclear Information System (INIS)

Popp, P.

1987-01-01

The study deals with application fields and basic design conceptions of manipulators in reactor pressure vessels as well as their evaluation. It is shown that manipulators supported at the reactor flange have essential advantages

Absorber rod bundle actuator in a pressurized water nuclear reactor

International Nuclear Information System (INIS)

Martin, J.; Peletan, R.

1984-01-01

The invention concerns an absorber rod bundle actuator in a pressurized water reactor with spectral shift control. The device comprises two coaxial control bars. The inner bar is integral with the absorber rod bundle; it has an enlarged zone which acts as a proton under pressure difference across an annular seal which can be radially expanded, the pressure difference allowing to the absorber rod bundles actuating on the piston. When a pressure difference is applied, the seal expands radially by a sufficient amount to make sealing contact with the zone of larger diameter in the outer bar. The invention applies more particularly to reactors with spectral shift control using bundles of fertile rods [fr

Study of the boron homogenizing process employing an experimental low-pressure bench simulating the IRIS reactor pressurizer – Part I

International Nuclear Information System (INIS)

Bezerra, Jair de Lima; Lira, Carlos Alberto Brayner de Oliveira; Barroso, Antonio Carlos de Oliveira; Lima, Fernando Roberto de Andrade; Bezerra da Silva, Mário Augusto

2013-01-01

Highlights: ► Experimental bench with test section made of transparent acrylic, simulating the pressurizer reactor IRIS. ► Workbench used to study the process of homogenization of boron in the pressurizer IRIS nuclear reactor. ► Results were obtained through videos and digital photos of the test section. - Abstract: The reactivity control of a nuclear reactor to pressurized water is made by means of controlling bars or by boron dilution in the water from the coolant of a primary circuit. The control with boron dilution has great importance, despite inserting small variations in the reactivity in the reactor, as it does not significantly affect the distribution of the neutron flux. A simplified experimental bench with a test section manufactured in transparent acrylic, was built in reduced scale as to be used in a boron homogenizing process, simulating an IRIS reactor pressurizer (International Reactor Innovative and Secure). The bench was assembled in the Centro Regional de Ciências Nucleares do Nordeste (CRCN-NE), an entity linked to the Comissão Nacional de Energia Nuclear (CNEN), Recife – PE

Study of the boron homogenizing process employing an experimental low-pressure bench simulating the IRIS reactor pressurizer – Part II

International Nuclear Information System (INIS)

Bezerra, Jair de Lima; Lira, Carlos Alberto Brayner de Oliveira; Barroso, Antonio Carlos de Oliveira; Lima, Fernando Roberto de Andrade; Silva, Mário Augusto Bezerra da

2013-01-01

Highlights: • Experimental bench with test section made of transparent acrylic, simulating the pressurizer reactor IRIS. • Workbench used to study the process of homogenization of boron in the pressurizer IRIS nuclear reactor. • Results were obtained through videos and digital photos of the test section. - Abstract: The reactivity control of a nuclear reactor to pressurized water is made by means of controlling bars or by boron dilution in the water from the coolant of a primary circuit. The control with boron dilution has great importance, despite inserting small variations in the reactivity in the reactor, as it does not significantly affect the distribution of the neutron flux. A simplified experimental bench with a test section manufactured in transparent acrylic, was built in reduced scale as to be used in a boron homogenizing process, simulating an IRIS reactor pressurizer (International Reactor Innovative and Secure). The bench was assembled in the Centro Regional de Ciências Nucleares do Nordeste (CRCN-NE), an entity linked to the Comissão Nacional de Energia Nuclear (CNEN), Recife–PE

Vandellos 1 NPP. Dismantling at the level 1

International Nuclear Information System (INIS)

Pla, E.; Perez Pallares, J.

1998-01-01

Because of the fire in a main turbogenerator in October 1989, the Spanish Ministry of Industry ordered the definitive shutdown of Vandellos 1 NPP. The tasks allowed to the owner in the Ministerial Order were: the reactor defueling, the operation radwaste conditioning. The size of the reactor core needed to prepare an adequate defueling plan in order to prevent the potential reactivity oscillations and ensure the refrigeration of the nuclear fuel remaining in the core. The operation radwastes were divided in four types, according to the conditioning method: the low level solid radwaste, the irradiated metallic materials, the resins and zeolites used for decontaminating the liquid effluents, the radwaste stored in three graphite silos. The low level solid radwastes were stored during operation in drums of 220 litres. Recently they were compacted at a pressure of 40 tones before to be shipped to en ENRESA disposal. The irradiated metallic materials are, essentially, some parts of the refuelling machine. For deactivating the liquid effluents, Vandellos 1 used both organic resins and zeolites. The presence of zeolites helps the cementation, but its rough surface makes difficult to flow in the pipes of the cementation plant. 35 m 3 of this mixture have been conditioned into 670 drums of 220 liters. Vandellos 1 has three silos designed to store the graphite sleeves (reactor fuel support). In the silo number 1 some other radwastes were stored, as low level solid radwastes and two fuel elements. An international request for tenders was made in order to undertake the extraction and conditioning all these radwastes. The project was awarded to the Spanish/French Consortium EQUIPOS NUCLEARES-FRAMATOME. The achievement of the graphite silos project needed to design specific devices for separating irradiated wires from graphite, and searching and extracting two fuel elements jumbled up with the graphite sleeves. The spent fuel ponds have been emptied and its internals confined

Dismantling of Vandellos I

International Nuclear Information System (INIS)

Armada, J. R.

2003-01-01

Spain is witnessing the phase-out of a nuclear power plant. It is a unique experience in our country and therefore the dismantling work has been watched closely, not only from here but also from abroad. The Empresa Nacional de Residuos Radiactivos (ENRESA) is in charge of managing the dismantling and decommissioning work of the Vandellos-I nuclear power plant, located in the municipality of L'Hospitalet de l'Infant (Tarragona). the work began five years ago and has been executed on schedule. the appearance of what was one of the first Spanish commercial nuclear power plants has been changed radically to leave premises suitable for any other activity. (Author)

STMI: several years of experience in nuclear plant dismantling

International Nuclear Information System (INIS)

Moreau, J.C.

1985-01-01

Since 1977, when STMI performed its first dismantling operation, the Company appreciably improved in that field through important operations: the dismantling of the calciothermy and fluoration metal Pu preparation facility, in La Hague reprocessing plant; the dismantling of the slag treatment chain, associated to calciothermy and fluoration processes, in La Hague reprocessing plant; and the cleaning of EL4 cell in Marcoule. To perform these operations, STMI's operating teams, on top of decontamination and dismantling technologies, strived to improve handling and transportation technologies, and to nuclearize many equipments. In order to increase its technical efficiency, STMI signed a cooperation agreement with FRAMATOME company. Therefore, the union between the operational know-hows of STMI and the design experience of TECHNICATOME allow the needs of any customs facing a dismantling case to be satisfied [fr

Self-pressurization analysis of the natural circulation integral nuclear reactor using a new dynamic model

Directory of Open Access Journals (Sweden)

Ali Farsoon Pilehvar

2018-06-01

Full Text Available Self-pressurization analysis of the natural circulation integral nuclear reactor through a new dynamic model is studied. Unlike conventional pressurized water reactors, this reactor type controls the system pressure using saturated coolant water in the steam dome at the top of the pressure vessel. Self-pressurization model is developed based on conservation of mass, volume, and energy by predicting the condensation that occurs in the steam dome and the flashing inside the chimney using the partial differential equation. A simple but functional model is adopted for the steam generator. The obtained results indicate that the variable measurement is consistent with design data and that this new model is able to predict the dynamics of the reactor in different situations. It is revealed that flashing and condensation power are in direct relation with the stability of the system pressure, without which pressure convergence cannot be established. Keywords: Condensation Power, Flashing Phenomenon, Natural Circulation, Self-Pressurization, Small Modular Reactor

Technical report on natural evaporation system for radioactive liquid waste treatment arising from TRIGA research reactors' decontamination and decommissioning activities

International Nuclear Information System (INIS)

Moon, J. S.; Jung, K. J.; Baek, S. T.; Jung, U. S.; Park, S. K.; Jung, K. H.

1999-01-01

This technical report described that radioactive liquid waste treatment for dismantling/decontamination of TRIGA Mark research reactor in Seoul. That is, we try safety treatment of operation radioactive liquid waste during of operating TRIGA Mark research reactor and dismantling radioactive liquid waste during R and D of research reactor hereafter, and by utilizing of new natural evaporation facility with describing design criteria of new natural evaporation facility. Therefore, this technical report described the quantity of present radioactive liquid waste and dismantling radioactive liquid waste hereafter, analysis the status of radial-rays/radioactivity, and also treatment method of this radioactive liquid waste. Also, we derived the method that the safeguard of outskirts environment and the cost down of radioactive liquid waste treatment by minimize of the radioactive liquid waste quantities, through-out design/operation of new natural evaporation facility for treatment of operation radioactive liquid waste and dismantling radioactive liquid waste. (author). 6 refs., 12 tabs., 5 figs

Modelling of SOEC-FT reactor: Pressure effects on methanation process

International Nuclear Information System (INIS)

Chen, Bin; Xu, Haoran; Ni, Meng

2017-01-01

Highlights: • Numerical study on combined SOEC-FT reactor in pressurized condition. • Effects of operating pressure on co-electrolysis and CH_4 production are studied. • The lower limit temperature of the FT section is dependent on the operating pressure. • The CH_4 production can be improved at higher voltage due to the current increase. • Effects of higher exchange current density is predicted at different temperature. - Abstract: In this paper a numerical model is developed for a novel reactor combining a Solid Oxide Electrolyzer Cell (SOEC) section with a Fischer Tropsch like section for methane production under pressurized & temperature-gradient condition. Governing equations for mass, momentum, charge transport are solved with Finite Element Method. The chemical reaction kinetics of reversible water gas shift reaction and reversible methanation reaction in Ni/YSZ cathode are fully considered. The model is validated by comparing simulation results with experimental data. Parametric simulations are conducted to understand the physical-chemical processes in the reactor with a focus on the pressure effect. It is predicted that the optimal operating pressure is around 3 bar, beyond which the CH_4 conversion ratio (2.5 times enhanced than 1 bar operating) cannot be further increased. It is also found that it is feasible to operate the pressurized SOEC at a lower temperature for CH_4 production with improved catalyst activity.

Use of superheated steam to anneal the reactor pressure vessel

International Nuclear Information System (INIS)

Porowski, J.S.

1994-01-01

Thermal annealing of an embrittled Reactor Pressure Shell is the only recognized means for recovering material properties lost due to long-term exposure of the reactor walls to radiation. Reduced toughness of the material during operation is a major concern in evaluations of structural integrity of older reactors. Extensive studies performed within programs related to life extension of nuclear plants have confirmed that the thermal treatment of 850 degrees F for 168 hours on irradiated material essentially recovers material properties lost due to neutron exposure. Dry and wet annealing methods have been considered. Wet annealing involves operating the reactor at near design temperatures and pressures. Since the temperature of wet annealing must be limited to vessel design temperature of 650 degrees F, only partial recovery of the lost properties is achieved. Thus dry annealing was selected as an alternative for future development and industrial implementation to extend the safe life of reactors

Fusion Reactor Materials

Energy Technology Data Exchange (ETDEWEB)

Decreton, M

2002-04-01

The objective of SCK-CEN's programme on fusion reactor materials is to contribute to the knowledge on the radiation-induced behaviour of fusion reactor materials and components as well as to help the international community in building the scientific and technical basis needed for the construction of the future reactor. Ongoing projects include: the study of the mechanical and chemical (corrosion) behaviour of structural materials under neutron irradiation and water coolant environment; the investigation of the characteristics of irradiated first wall material such as beryllium; investigations on the management of materials resulting from the dismantling of fusion reactors including waste disposal. Progress and achievements in these areas in 2001 are discussed.

Activation calculation for the dismantling and decommissioning of a light water reactor using MCNP™ with ADVANTG and ORIGEN-S

Directory of Open Access Journals (Sweden)

Schlömer Luc

2017-01-01

Full Text Available The decommissioning of a light water reactor (LWR, which is licensed under § 7 of the German Atomic Energy Act, following the post-operational phase requires a comprehensive licensing procedure including in particular radiation protection aspects and possible impacts to the environment. Decommissioning includes essential changes in requirements for the systems and components and will mainly lead to the direct dismantling. In this context, neutron induced activation calculations for the structural components have to be carried out to predict activities in structures and to estimate future costs for conditioning and packaging. To avoid an overestimation of the radioactive inventory and to calculate the expenses for decommissioning as accurate as possible, modern state-of-the-art Monte-Carlo-Techniques (MCNP™ are applied and coupled with present-day activation and decay codes (ORIGEN-S. In this context ADVANTG is used as weight window generator for MCNP™ i. e. as variance reduction tool to speed up the calculation in deep penetration problems. In this paper the calculation procedure is described and the obtained results are presented with a validation along with measured activities and photon dose rates measured in the post-operational phase. The validation shows that the applied calculation procedure is suitable for the determination of the radioactive inventory of a nuclear power plant. Even the measured gamma dose rates in the post-operational phase at different positions in the reactor building agree within a factor of 2 to 3 with the calculation results. The obtained results are accurate and suitable to support effectively the decommissioning planning process.

Activation calculation for the dismantling and decommissioning of a light water reactor using MCNP™ with ADVANTG and ORIGEN-S

Science.gov (United States)

Schlömer, Luc; Phlippen, Peter-W.; Lukas, Bernard

2017-09-01

The decommissioning of a light water reactor (LWR), which is licensed under § 7 of the German Atomic Energy Act, following the post-operational phase requires a comprehensive licensing procedure including in particular radiation protection aspects and possible impacts to the environment. Decommissioning includes essential changes in requirements for the systems and components and will mainly lead to the direct dismantling. In this context, neutron induced activation calculations for the structural components have to be carried out to predict activities in structures and to estimate future costs for conditioning and packaging. To avoid an overestimation of the radioactive inventory and to calculate the expenses for decommissioning as accurate as possible, modern state-of-the-art Monte-Carlo-Techniques (MCNP™) are applied and coupled with present-day activation and decay codes (ORIGEN-S). In this context ADVANTG is used as weight window generator for MCNP™ i. e. as variance reduction tool to speed up the calculation in deep penetration problems. In this paper the calculation procedure is described and the obtained results are presented with a validation along with measured activities and photon dose rates measured in the post-operational phase. The validation shows that the applied calculation procedure is suitable for the determination of the radioactive inventory of a nuclear power plant. Even the measured gamma dose rates in the post-operational phase at different positions in the reactor building agree within a factor of 2 to 3 with the calculation results. The obtained results are accurate and suitable to support effectively the decommissioning planning process.

The WAK decommissioning and dismantling program

International Nuclear Information System (INIS)

Eiben, K.; Fritz, P.

1995-01-01

After an extensive rinsing of the reprocessing equipment the operation in the plant was terminated in 1991 following the principal political decision to abolish reprocessing of nuclear fuel in Germany. Since July 1991 only the safety relevant units are still in operation including the waste storage facilities for 80 m 3 of high active waste concentrate (HAWC). The decommissioning and dismantling will be achieved in six steps taking into account that some of the reprocessing equipment can be dismantled before and the rest only after the HAWC has been vitrified approximately by mid 2000. So far two licenses for decommissioning have been granted. An application for the dismantling of twelve systems in the process building including headend and tailend facilities will be licensed in 1995. The remote dismantling of equipment from the hot cells in the process building is being planned and will be executed between 1998--2001. New remote handling equipment will be cold tested in a test facility scheduled to start in the middle of this year. The final task is the green meadow after demolishing of the building and remediation of the site which is scheduled for 2005

Manipulator for testing a top-opened reactor pressure vessel

International Nuclear Information System (INIS)

Bauer, R.; Kastl, H.

1991-01-01

The design is described of a manipulator to be inserted into the inside of reactor pressure vessels opened at the top. The main components of the manipulator include a fixed column protruding into the pressure vessel and a support which is slidable on the column and carries the bearing component for the measuring, testing, inspection and repair instruments. The device includes a driving equipment for the support as well as the power supply for the sets accommodated on the support, with the aim to reduce the failure rate of the manipulator as a whole, shorten the time necessary for its assembling and thus the time of staying in the reactor pressure vessel and, at the same time, make its maintenance and operation easier. (Z.S.). 13 figs

Testing of acoustic emission method during pressure tests of WWER-440 steam generators and pressurizers

International Nuclear Information System (INIS)

Wuerfl, K.; Crha, J.

1987-01-01

The results are discussed of measuring acoustic emission in output pressure testing of steam generators and pressurizers for WWER-440 reactors. The objective of the measurements was to test the reproducibility of measurements and to find the criterion which would be used in assessing the condition of the components during manufacture and in operation. The acoustic emission was measured using a single-channel Dunegan/Endevco apparatus and a 16-channel LOCAMAT system. The results showed that after the first assembly, during a repeat dismantle of the lids and during seal replacement, processes due to seal contacts and bolt and washer deformations were the main source of acoustic emission. A procedure was defined of how to exclude new acoustic emission sources in such cases. The acoustic emission method can be used for the diagnostics of plastic deformation processes or of crack production and propagation in components during service. (Z.M.)

Interfacing systems LOCA (loss-of-coolant accidents): Pressurized water reactors

International Nuclear Information System (INIS)

Bozoki, G.; Kohut, P.; Fitzpatrick, R.

1989-02-01

This report summarizes a study performed by Brookhaven National Laboratory for the Office of Nuclear Regulatory Research, Reactor and Plant Safety Issues Branch, Division of Reactor and Plant Systems, US Nuclear Regulatory Commission. This study was requested by the NRC in order to provide a technical basis for the resolution of Generic Issue 105 ''Interfacing LOCA at LWRs.'' This report deals with pressurized water reactors (PWRs). A parallel report was also accomplished for boiling water reactors. This study focuses on three representative PWRs and extrapolates the plant-specific findings for their generic applicability. In addition, a generic analysis was performed to investigate the cost-benefit aspects of imposing a testing program that would require some minimum level of leak testing of the pressure isolation valves on plants that presently have no such requirements. 28 refs., 31 figs., 64 tabs

TORT application in reactor pressure vessel neutron flux calculations

International Nuclear Information System (INIS)

Belousov, S.I.; Ilieva, K.D.; Antonov, S.Y.

1994-01-01

The neutron flux values onto reactor pressure vessel for WWER-1000 and WWER-440 reactors, at the places important for metal embrittlement surveillance have been calculated by 3 dimensional code TORT and synthesis method. The comparison of the results received by both methods confirms their good consistency. (authors). 13 refs., 4 tabs

Arkansas Tech University TRIGA nuclear reactor

International Nuclear Information System (INIS)

Sankoorikal, J.; Culp, R.; Hamm, J.; Elliott, D.; Hodgson, L.; Apple, S.

1990-01-01

This paper describes the TRIGA nuclear reactor (ATUTR) proposed for construction on the campus of Arkansas Tech University in Russellville, Arkansas. The reactor will be part of the Center for Energy Studies located at Arkansas Tech University. The reactor has a steady state power level of 250 kW and can be pulsed with a maximum reactivity insertion of $2.0. Experience gained in dismantling and transporting some of the components from Michigan State University, and the storage of these components will be presented. The reactor will be used for education, training, and research. (author)

Probabilistic integrity assessment of pressure tubes in an operating pressurized heavy water reactor

Energy Technology Data Exchange (ETDEWEB)

Oh, Young-Jin; Park, Heung-Bae [KEPCO E and C, 188 Gumi-dong, Bundang-gu, Seongnam-si, Gyeonggi-do 463-870 (Korea, Republic of); Lee, Jung-Min; Kim, Young-Jin [School of Mechanical Engineering, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon-si, Gyeonggi-do 440-746 (Korea, Republic of); Ko, Han-Ok [Korea Institute of Nuclear Safety, 34 Gwahak-ro, Yuseong-gu, Daejeon-si 305-338 (Korea, Republic of); Chang, Yoon-Suk, E-mail: yschang@khu.ac.kr [Department of Nuclear Engineering, Kyung Hee University, 1 Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of)

2012-02-15

Even though pressure tubes are major components of a pressurized heavy water reactor (PHWR), only small proportions of pressure tubes are sampled for inspection due to limited inspection time and costs. Since the inspection scope and integrity evaluation have been treated by using a deterministic approach in general, a set of conservative data was used instead of all known information related to in-service degradation mechanisms because of inherent uncertainties in the examination. Recently, in order that pressure tube degradations identified in a sample of inspected pressure tubes are taken into account to address the balance of the uninspected ones in the reactor core, a probabilistic approach has been introduced. In the present paper, probabilistic integrity assessments of PHWR pressure tubes were carried out based on accumulated operating experiences and enhanced technology. Parametric analyses on key variables were conducted, which were periodically measured by in-service inspection program, such as deuterium uptake rate, dimensional change rate of pressure tube and flaw size distribution. Subsequently, a methodology to decide optimum statistical distribution by using a robust method adopting a genetic algorithm was proposed and applied to the most influential variable to verify the reliability of the proposed method. Finally, pros and cons of the alternative distributions comparing with corresponding ones derived from the traditional method as well as technical findings from the statistical assessment were discussed to show applicability to the probabilistic assessment of pressure tubes.

Dismantling without contaminating: The EUREX plant experience

International Nuclear Information System (INIS)

2001-01-01

The EUREX pilot plant of ENEA Research Centre of Saluggia (Italy) reprocessed, between 1970 and 1983, some 600 elements and 1.5 tonnes of irradiated fuel from MTR and CANDU reactors. The general programme of denuclearization of the site actually focuses on the main priority of the conditioning of the about 400 m 3 of High and Low Level Liquid wastes stored in Saluggia. For this reason, in 1997 a project for the H and LLW conditioning, named 'CORA' has started. The 'CORA' unit will solidify the liquid wastes applying the Cold Crucible Melter (CCM) technology; due to the low volume amount of wastes to vitrify, the 'CORA' project has been accurately tailored in order to reduce social impact on public acceptance, costs and conditioning plant volumes to dismantle at the end of the work. For this reason, all the main nuclear components of the conditioning unit (input tank and pretreatment section, CC Melter, pot handling, off-gas system, interim glass storage) will be hosted inside four existing cells of the EUREX plant, duly dismantled. The EUREX plant services (electric and process fluid supplies, controlled areas, ventilation system...) will be reused too, revamped in some cases. The reuse of a nuclear plant which was built in the 60's, as the EUREX is, for future conditioning activities to be 'transplanted' there in the next years, it is not quite an easy job: the partial EUREX dismantling must permit an easy recovery of process areas and spread of contamination from old components (tanks, pipes, valves...) has to be minimized as far as possible. In order to minimize contamination spread, pipe cutting is made by a hydraulic shear, leaving the cut edges closed. Size reduction of pipes and tanks, to optimize the 5 m 3 steel storage containers filling is, as far as possible, made out of the working area of the cells. To achieve this goal a preliminary sketch of pipes to be cut and where the minimal cuts ought to be done is prepared before each intervention. The time

Microstructural evolution in neutron irradiated reactor pressure vessel steels

International Nuclear Information System (INIS)

English, C.A.; Phythian, W.J.

1998-01-01

As a result of the popularity of the Agencies report 'Neutron Irradiation Embrittlement of Reactor Pressure Vessel Steels' of 1975, it was decided that another report on this broad subject would be of use. In this report, background and contemporary views on specially identified areas of the subject are considered as self-contained chapters, written by experts. The microstructural evolution in neutron irradiated reactor pressure vessel steels is described. The damage mechanisms are elaborated and techniques for examining the microstructure are suggested. The importance of the initial damage event is analysed, and the microstructural evolution in RPV steels is examined

Some local dilution transient in a pressurized water reactor

International Nuclear Information System (INIS)

Jacobson, S.

1989-01-01

Reactivity accidents are important in the safety analysis of a pressurized water reactor. In this anlysis ejected control rod, steam line break, start of in-active loop and boron dilution accidents are usually dealt with. However, in the analysis is not included what reactivity excursions might happen when a zone,depleted of boron passes the reactor core. This thesis investigates during what operation and emergency conditions diluted zones might exist in a pressurized water reactor and what should be the maximum volumes for then. The limiting transport means are also established in terms of reactivty addition, for the depleted zones. In order to describe the complicated mixing process in the reactor vessel during such a transportation, a typical 3-loop reactor vessel has been modulated by means of TRAC-PF1's VESSEL component. Three cases have been analysed. In the first case the reactor is in a cold condition and the ractor coolant has boron concentration of 2000 ppm. To the reactor vessel is injected an clean water colume of 14 m 3 . In the two other cases the reactor is close to hot shutdown and borated to 850 ppm. To the reactor vessel is added 41 and 13 m 3 clean water, respectively. In the thesis is shown what spatial distribution the depleted zone gets when passing through the reactor vessel in the three cases. The boron concentration in the first case did not decrease the values which would bring the reactor to critical condition. For case two was shown by means of TRAC's point kinetics model that the reactor reaches prompt criticality after 16.03 seconds after starting of the reactor coolant pump. Another prompt criticality occured two seconds later. The total energy developed during the two power escalations were about 55 GJ. A comparision with the criteria used to evaluate the ejected control rod reactivity transient showed that none of these criteria were exceeded. (64 figs.)

Electrochemical noise measurements under pressurized water reactor conditions

International Nuclear Information System (INIS)

Van Nieuwenhove, R.

2000-01-01

Electrochemical potential noise measurements on sensitized stainless steel pressure tubes under pressurized water reactor (PWR) conditions were performed for the first time. Very short potential spikes, believed to be associated to crack initiation events, were detected when stressing the sample above the yield strength and increased in magnitude until the sample broke. Sudden increases of plastic deformation, as induced by an increased tube pressure, resulted in slower, high-amplitude potential transients, often accompanied by a reduction in noise level

Light-water-reactor pressure-vessel surveillance dosimetry using solid-state track recorders

International Nuclear Information System (INIS)

Ruddy, F.H.; Roberts, J.H.; Gold, R.; Preston, C.C.

1983-07-01

The accumulation of neutron dose by the pressure vessel of an operating nuclear power plant results in damage in the form of steel embrittlement. In order to ascertain the safe operating lifetime of the reactor pressure vessel, dosimetric measurements must be made to evaluate the neutron dose to the pressure vessel and relate this dose to the cumulative radiation damage. Advanced dosimetry techniques are being evaluated for surveillance of operating reactors. Solid-state track recorder (SSTR) techniques are included among these advanced dosimetry techniques. Described herein are low neutron fluence calibration and standardization measurements that are being carried out in pressure vessel mockup benchmark neutron fields in the USA, Belgium, and England. In addition, high fluence SSTR dosimetry capsules have been irradiated with metallurgical specimens in a pressure vessel mockup facility. The design and deployment of advances SSTR dosimetry capsules in operating power reactors are also described

Neutron irradiation effects in reactor pressure vessel steels and weldments. Working document

International Nuclear Information System (INIS)

1998-10-01

As a result of the popularity of the Agencies report 'Neutron Irradiation Embrittlement of Reactor Pressure Vessel Steels' of 1975, it was decided that another report on this broad subject would be of use. In this report, background and contemporary views on specially identified areas of the subject are considered as self-contained chapters, written by experts. A separate abstract was prepared for the introduction and for each of the eleven chapters, which are: 1. Reactor Pressure Vessel Design, 2. Reactor Pressure Materials, 3. WWER Pressure Vessels, 4. Determination of Mechanical Properties, 5. Neutron Exposure, 6. Methodology of Irradiation Experiments, 7. Effect of Irradiation on Mechanical Properties, 8. Mechanisms of Irradiation Embrittlement, 9. Modelling of Irradiation Damage, 10. Annealing of Irradiation Damage, 11. Safety Assessment using Surveillance Programmes and Data Bases

Pressurized water reactor simulator. Workshop material. 2. ed

International Nuclear Information System (INIS)

2005-01-01

The International Atomic Energy Agency (IAEA) has established an activity in nuclear reactor simulation computer programs to assist its Member States in education. The objective is to provide, for a variety of advanced reactor types, insight and practice in their operational characteristics and their response to perturbations and accident situations. To achieve this, the IAEA arranges for the development and distribution of simulation programs and educational material and sponsors courses and workshops. The workshops are in two parts: techniques and tools for reactor simulator development. And the use of reactor simulators in education. Workshop material for the first part is covered in the IAEA Training Course Series No. 12, 'Reactor Simulator Development' (2001). Course material for workshops using a WWER- 1000 reactor department simulator from the Moscow Engineering and Physics Institute, the Russian Federation is presented in the IAEA Training Course Series No. 21, 2nd edition, 'WWER-1000 Reactor Simulator' (2005). Course material for workshops using a boiling water reactor simulator developed for the IAEA by Cassiopeia Technologies Incorporated of Canada (CTI) is presented in the IAEA publication: Training Course Series No.23, 2nd edition, 'Boiling Water Reactor Simulator' (2005). This report consists of course material for workshops using a pressurized water reactor simulator

Decontamination and remote dismantling tests in the Itrec reprocessing plant

International Nuclear Information System (INIS)

Candelieri, T.; Gerardi, A.; Soffietto, G.

1993-01-01

The scope of this research is to evaluate the advantages of the rack removal system in the dismantling of reprocessing installations. The objective of this work is to verify experimentally the possibility of the decontamination of any particular module and the capability of the remote dismantling of components installed in the mobile rack. In particular, the main objective is to develop remotely operated equipment for the dismantling of centrifugal contactors. The decontamination of the equipment which represents the most important preliminary phase of the decommissioning operation, allowed to obtain low-level radioactivity. A supporting programme has been performed in order to collect sufficient data for the project and design of the remote dismantling machine. On the basis of technological cold test results, the project of the dismantling machine's construction has been optimized. Positive results obtained during the hot dismantling operations on the Rack 6 bis attested the effectiveness of the rack removal system as an original design which facilitates decommissioning of reprocessing plants. 2 tabs., 18 figs

Management routes for materials arising from the decommissioning of a PWR reactor

International Nuclear Information System (INIS)

Klein, M.; Demeulemeester, Y.; Moers, S.; Ponnet, M.

2001-01-01

The management of wastes from decommissioning is described for the on-going dismantling of the BR3 PWR small reactor. The incentive is put on the radionuclides characterization, the description of the various waste streams, the conditioning techniques for low radioactive waste (LAW) to high radioactive waste (RAW), the alternative evacuation routes (recycling in the nuclear, free release by decontamination) and the minimization of secondary wastes during dismantling. Finally, some considerations are given on the overall dismantling cost and on the relative costs of the various evacuation routes. (author)

In-service ultrasonic inspection of nuclear reactor pressure vessels

International Nuclear Information System (INIS)

Prepechal, J.; Sulc, J.

1982-01-01

Ultrasonic tests of pressure vessels for WWER 440 reactors, type 213 V, are carried out partly manually and partly by test equipment. The inner surface of the pressure vessel is tested using device REACTORTEST TRC which is fully mobile. The outer surface of the cylindrical parts and bottoms of the body is tested using handling equipment permanently in-built under the pressure vessel and dismountable testing heads. A set of these heads may be used for two reactor units. The testing equipment REACTORTEST TRC is equipped with a TRC 800 ultrasound device. The equipment for testing the outer surface of the vessel operates with the UDAR 16 ultrasound apparatus to which may be simultaneously connected 10 ultrasound probes and six probes for acoustic feedback. The whole system of ultrasonic tests makes possible a first-rate and reliable volume control of the whole pressure vessel and all points where cracks may originate and grow. (Z.M.)

Decommissioning and decontamination of licensed reactor facilities and demonstration nuclear power plants

International Nuclear Information System (INIS)

Lear, G.; Erickson, P.B.

1975-01-01

Decommissioning of licensed reactors and demonstration nuclear power plants has been accomplished by mothballing (protective storage), entombment, and dismantling or a combination of these three. The alternative selected by a licensee seems to be primarily based on cost. A licensee must, however, show that the decommissioning process provides adequate protection of the health and safety of the public and no adverse impact on the environment. To date the NRC has approved each of the alternatives in the decommissioning of different facilities. The decommissioning of small research reactors has been accomplished primarily by dismantling. Licensed nuclear power plants, however, have been decommissioned primarily by being placed in a mothballed state in which they continue to retain a reactor license and the associated licensee responsibilities

Overview of recycling technologies for decommissioned materials. Lessons learned during the dismantling of a small PWR reactor

International Nuclear Information System (INIS)

Klein, M.; Emond, O.; Ponnet, M.

2001-01-01

Full text: SCK CEN is dismantling its 11 MWe PWR reactor. The reactor was shutdown in 1987 after 25 years of operation and the dismantling started in 1990. For the management of the low radioactive materials, we apply a strategy promoting the minimisation of the production of radioactive waste and hence the maximisation of the production of recycled materials while keeping the costs as low as possible. The recycled materials are either reused in the non- nuclear industry as raw materials (metal scrap industry or building industry for the concrete) or recycled in the nuclear industry for specific applications (reuse of metals for fabrication of shielding, potential reuse of concrete for production of 'radioactive mortar'). The clearance of radioactive materials and their reuse require the strict respect of procedures and specifications. In our case, the Health Physics department under supervision of the Competent Authority establishes the procedures. This procedure is still a case by case practice but the legislation in Belgium is progressively put in place. For the recycling in the nuclear industry, we must respect the specifications of the end-user. Up to now, we have recycled low radioactive metals for the fabrication of shielding in the USA, so we had to respect the specifications of the melting facility and to obtain the authorisations for the transport abroad and for the transfer of property. Besides the radioactive waste route, we are using several evacuation routes for the dismantled materials: Evacuation of the cleared metals (iron, stainless steel, copper, electric motors...) to a local scrap dealer; Evacuation of metals to the Studsvik melting facility situated in Sweden: after clearance by the Swedish Authority, the non radioactive materials are sent to a local scrap dealer and the secondary radioactive waste is sent back to Belgium and conditioned by Belgoprocess. This technology further decontaminates the metals and allows performing an accurate

Pressure-accelerated azide-alkyne cycloaddition: micro capillary versus autoclave reactor performance.

Science.gov (United States)

Borukhova, Svetlana; Seeger, Andreas D; Noël, Timothy; Wang, Qi; Busch, Markus; Hessel, Volker

2015-02-01

Pressure effects on regioselectivity and yield of cycloaddition reactions have been shown to exist. Nevertheless, high pressure synthetic applications with subsequent benefits in the production of natural products are limited by the general availability of the equipment. In addition, the virtues and limitations of microflow equipment under standard conditions are well established. Herein, we apply novel-process-window (NPWs) principles, such as intensification of intrinsic kinetics of a reaction using high temperature, pressure, and concentration, on azide-alkyne cycloaddition towards synthesis of Rufinamide precursor. We applied three main activation methods (i.e., uncatalyzed batch, uncatalyzed flow, and catalyzed flow) on uncatalyzed and catalyzed azide-alkyne cycloaddition. We compare the performance of two reactors, a specialized autoclave batch reactor for high-pressure operation up to 1800 bar and a capillary flow reactor (up to 400 bar). A differentiated and comprehensive picture is given for the two reactors and the three methods of activation. Reaction speedup and consequent increases in space-time yields is achieved, while the process window for favorable operation to selectively produce Rufinamide precursor in good yields is widened. The best conditions thus determined are applied to several azide-alkyne cycloadditions to widen the scope of the presented methodology. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A model for structural analysis of nuclear reactor pressure vessel flanges

International Nuclear Information System (INIS)

Oliveira, C.A. de.

1987-01-01

Due to the recent Brazilian advances in the nuclear technology area, it has been necessary the development of design and analysis methods for pressurized water reactor components, also as other components of a nuclear plant. This work proposes a methodology for the structural analysis of large diameter nuclear reactor pressure vessel flanges. In the analysis the vessel is divided into shell-of-revolution elements, the flanges are represented by rigid rings, and the bolts are treated as beams. The flexibility method is used for solving the problem. A computer program is shown, and the given results (displacements and stresses) are compared with results obtained by the finite element method. Although developed for nuclear reactor pressure vessel calculations, the program is more general, being possible its use for the analysis of any structure composed by shells of revolution. (author)

Lessons Learned From Developing Reactor Pressure Vessel Steel Embrittlement Database

Energy Technology Data Exchange (ETDEWEB)

Wang, Jy-An John [ORNL

2010-08-01

Materials behaviors caused by neutron irradiation under fission and/or fusion environments can be little understood without practical examination. Easily accessible material information system with large material database using effective computers is necessary for design of nuclear materials and analyses or simulations of the phenomena. The developed Embrittlement Data Base (EDB) at ORNL is this comprehensive collection of data. EDB database contains power reactor pressure vessel surveillance data, the material test reactor data, foreign reactor data (through bilateral agreements authorized by NRC), and the fracture toughness data. The lessons learned from building EDB program and the associated database management activity regarding Material Database Design Methodology, Architecture and the Embedded QA Protocol are described in this report. The development of IAEA International Database on Reactor Pressure Vessel Materials (IDRPVM) and the comparison of EDB database and IAEA IDRPVM database are provided in the report. The recommended database QA protocol and database infrastructure are also stated in the report.

Enriched uranium cycles in pressurized heavy water reactors

International Nuclear Information System (INIS)

Mazzola, A.

1994-01-01

A study was made on the substitution of natural uranium with enriched and on plutonium recycle in unmodified PHWRs (pressure vessel reactor). Results clearly show the usefulness of enriched fuel utilisation for both uranium ore consumption (savings of 30% around 1.3% enrichment) and decreasing fuel cycle coasts. This is also due to a better plutonium exploitation during the cycle. On the other hand plutonium recycle in these reactors via MOX-type fuel appears economically unfavourable under any condition

Light-water reactor pressure vessel surveillance standards

International Nuclear Information System (INIS)

Anon.

1981-01-01

The master matrix standard describes a series of standard practices, guides, and methods for the prediction of neutron-induced changes in light-water reactor (LWR) pressure vessel steels throughout a pressure vessel's service life. Some of these are existing American Society for Testing and Materials (ASTM) standards, some are ASTM standards that have been modified, and some are newly proposed ASTM standards. The current (1) scope, (2) areas of application, (3) interrelationships, and (4) status and time table of development, improvement, validation, and calibration for a series of 16 ASTM standards are defined. The standard also includes a discussion of LWR pressure vessel surveillance - justification, requirements, and status of work

Nuclear power - replacement of pressure tubes in CANDU reactors

International Nuclear Information System (INIS)

Anon.

1992-01-01

The CANDU pressure tube reactor is an effective electricity generator. While most units have been built in Canada, units are successfully operated in Argentina and Korea as well as India and Pakistan, which have early versions of the same concept. Units are also under construction in Korea and Romania. The main constructional components of a CANDU core are the calandria vessel, the fuel channels and the reactivity control mechanisms. The fuel channel, in particular the pressure tubes, see an environment comprising high flux, high temperature water at high pressures, which induces changes in the properties and dimensions of the channel components. From the first, fuel channels were designed to be replaced because of the difficulty in predicting the behaviour of zirconium alloys in such service over a long period of time. In fact some phenomena, that were not known at the time of the earliest designs, have led to unacceptable changes in the properties of the channels and these early reactors have had to be retubed at half their intended life. These deficiencies have been corrected in the latest designs and fuel channels in reactors that have commenced operation over the last 10 years, are predicted to reach the intended 30 years life before replacement is necessary. The changing of fuel channels, the details and experience of which are explained, has been shown to be an effective way of refurbishing the CANDU reactor, extending its lifetime a further 25-30 years. (author)

The Westinghouse Advanced Passive Pressurized Water Reactor, AP1000

International Nuclear Information System (INIS)

Schene, R.

2009-01-01

Featuring proven technology and innovative passive safety systems, the Westinghouse AP1000 pressurized water reactor can achieve competitive generation costs in the current electricity market without emitting harmful greenhouse gases and further harming the environment. Westinghouse Electric Company, the pioneer in nuclear energy once again sets a new industry standard with the AP1000. The AP1000 is a two-loop pressurized water reactor that uses simplified, innovative and effective approach to safety. With a gross power rating of 3415 megawatt thermal and a nominal net electrical output of 1117 megawatt electric, the AP1000 is ideal for new base load generation. The AP1000 is the safest and most economical nuclear power plant available in the worldwide commercial marketplace, and is the only Generation III+ reactor to receive a design certification from the U.S. Nuclear Regulatory Commission (NRC). Based on nearly 20 years of research and development, the AP1000 builds and improves upon the established technology of major components used in current Westinghouse designed plants. These components, including steam generators, digital instrumentation and controls, fuel, pressurizers, and reactor vessels, are currently in use around the world and have years of proven, reliable operating experience. Historically, Westinghouse plant designs and technology have forged the cutting edge technology of nuclear plant around the world. Today, nearly 50 percent of the world's 440 nuclear plants are based on Westinghouse technology. Westinghouse continues to be the nuclear industry's global leader. (author)

EDF's nuclear safety approach for pressurized water reactors

International Nuclear Information System (INIS)

Tanguy, P.; Kus, J.P.

1987-01-01

The realization of the important French program fifty-four units equipped with pressurized water reactors in service, or under construction-had led to the progressive implementation of an original approach in the field of nuclear safety. From an initial core consisting of the deterministic approach to safety devised on the other side of the Atlantic, which has been entirely preserved and often specified, further extras have been added which overall increase the level of safety of the installations, without any particular complications. This paper aims at presenting succinctly the outcome of the deliberation, which constitutes now the approach adopted by Electricite de France for the safety of nuclear units equipped with pressurized water reactors. This approach is explained in more detail in EDF's 'with book' on nuclear safety. (author)

EDF'S nuclear safety approach for pressurized water reactors

International Nuclear Information System (INIS)

Tanguy, P.; Kus, J.P.

1988-01-01

The realization of the important French program fifty-four units equipped with pressurized water reactors in service, or under construction - had led to the progressive implementation of an original approach in the field of nuclear safety. From an initial core consisting of the deterministic approach to safety devised on the other side of the Atlantic, which has been entirely preserved and often specified, further extras have been added which overall increase the level of safety of the installations, without any particular complications. This paper aims at presenting succinctly the outcome of the deliberation, which constitutes now the approach adopted by Electricite de France for the safety of nuclear units equipped with pressurized water reactors. This approach is explained in more detail in EDF's white book on nuclear safety

The market of nuclear plant dismantling. The new EDF's strategy, process standardisation, robotization: which perspectives for the market by 2030?

International Nuclear Information System (INIS)

2017-09-01

Dismantling appears as the most promising activity in the nuclear sector due to ageing plants, to ambitious objectives of reduction of the nuclear share in the energy mix, or to high expertise of French companies in robotic and digital solutions for deconstruction in radioactive environments. However, the development of the dismantling market depends on EDF decisions: the extension of nuclear reactor lifetime postpones the development of this market. In this context, this study aims at giving an anticipated view of the plant dismantling market by 2030, at deciphering growth levers for the sector actors, and at understanding the sector operation and the business model of operators. Thus, the report presents the main components of the market (key figures, dismantling types, dismantling steps, sector ecosystem, barriers to enter the market, costs, contractual relationships), proposes an analysis of the market and of its perspectives (situation in France, and at the world level, predictive scenario for 2030), and discusses the development axes and demand evolutions (robotization and digitalisation, elaboration of standardised processes, management of wastes produced by nuclear dismantling, internationalisation of French actors). It also proposes an overview of actors in France, and identity sheets for commissioners (EDF, New Areva), contractors (Onet, Vinci, Engie), and other actors (Veolia, Assystem, Ortec, Cybernetix, Oreka Group). The last part proposes synthetic sheets for more than 110 companies of the sector (general information, management and financial performance data under the form of tables and figures) and comparative tables according to 5 key indicators. Data are presented for a period ranging from 2010 to 2016

Regulatory supervision of the radiation protection and release during the dismantling of the German NPP Wuergassen

International Nuclear Information System (INIS)

Boerchers, F.; Hillberg, M.

2003-01-01

The NPP Wuergassen (KWW) is a commercial, single unit boiling water reactor with a capacity of 670 MW el . It was commissioned by PreussenElektra and constructed by AEG/KWU between 1968 and 1971. This NPP was finally shut down in 1994. The decommissioning, started in April 1997, is still under progress. Up to now, approx. 9,500 Mg of various materials (e.g. metal scrap, cable, concrete) have been deconstructed and released from the site. In this paper we describe the contribution from the authority and the independent expert during the radiological characterisation, the dismantling work, and the material flow up to the release. Special focus will be on the necessary control steps and the documentation regarding the dismantling work and the procedure of release. There is always a close fit between the radiation protection and the release of material on the basis of the radiological characterisation. (authors)

Environmental Assessment for decontamination and dismantlement, Pinellas Plant

International Nuclear Information System (INIS)

1995-06-01

The US Department of Energy (DOE) has prepared an Environmental Assessment (EA) (DOE/EA-1092) of the proposed decontamination and dismantlement of the Pinellas Plant in Largo, Florida. Under the Decontamination and Dismantlement EA, the DOE proposes to clean up facilities, structures, and utilities; dismantle specific structures; and mitigate or eliminate any environmental impacts associated with the cleanup, dismantlement, and related activities. Related activities include utilization of specific areas by new tenants prior to full-scale cleanup. Based on the analyses in the EA, the DOE has determined that the proposed action is not a major Federal action significantly affecting the quality of the human environment, within the meaning of the National Environmental Policy Act of 1969. Therefore, the preparation of an environmental impact statement is not required. This report contains the Environmental Assessment, as well as the Finding of No Significant Impact (FONSI)

The dynamic pressure measurements of the nuclear reactor coolant for condition-based maintenance of the reactor

International Nuclear Information System (INIS)

Es-Saheb, M.H.H.

1990-01-01

The condition-based maintenance of the nuclear reactor, by monitoring and measuring the instantaneous dynamic pressure distribution of the coolant (water) impact on the solid surfaces of the reactor during operation is presented. The behaviour of water domes (jets) produced by underwater explosions of small changes of P.E.T.N. at various depths in two different size cylindrical containers, which simulate the nuclear reactor, is investigated. Water surface domes (jets) from the underwater explosions are photographed. Depending on the depth of the charge, curved and flat top jets of up to 455 mm diameter and impact speeds of up to 70 m/sec. are observed. The instabilities in the dome surfaces are observed and the instantaneous profiles are analysed. It is found that, in all cases tested, the maximum pressure takes place at the center of the jet and could reach up to 3.0 times the on-dimensional impact pressure value. The use of their measurements, as online monitoring for condition-based maintenance and design-out maintenance is discussed. 18 refs

Impact of radiation embrittlement on integrity of pressure vessel supports for two PWR [pressurized-water-reactor] plants

International Nuclear Information System (INIS)

Cheverton, R.D.; Pennell, W.E.; Robinson, G.C.; Nanstad, R.K.

1988-01-01

Recent pressure-vessel surveillance data from the High Flux Isotope Reactor (HFIR) indicate an embrittlement fluence-rate effect that is applicable to the evaluation of the integrity of light-water reactor (LWR) pressure vessel supports. A preliminary evaluation using the HFIR data indicated increases in the nil ductility transition temperature at 32 effective full-power years (EFPY) of 100 to 130/degree/C for pressurized-water-reactor (PWR) vessel supports located in the cavity at midheight of the core. This result indicated a potential problem with regard to life expectancy. However, an accurate assessment required a detailed, specific-plant, fracture-mechanics analysis. After a survey and cursory evaluation of all LWR plants, two PWR plants that appeared to have a potential problem were selected. Results of the analyses indicate minimum critical flaw sizes small enough to be of concern before 32 EFPY. 24 refs., 16 figs., 7 tabs

Pressure suppression system for a nuclear reactor

International Nuclear Information System (INIS)

Jost, N.

1977-01-01

The invention pertains to a pressure suppression system for PWR reactors where the parts enclosing the primary coolant are contained in two pressure-tight separate chambers. According to the invention, these chambers are partly filled with water and are connected with each other below the water surface. This way, gases cannot escape from the containment, not even if a valve and a line are damaged at the same time, as the vapours released condensate in the water of at least one of the other chambers. (HP) [de

Decree no. 2005-78 from January 26, 2005, authorizing the Atomic Energy Commission to proceed to the definitive shutdown and dismantling operations of the nuclear facility no.20, named Siloe reactor, in the Grenoble city territory (Isere)

International Nuclear Information System (INIS)

2005-02-01

On March 19, 2003, the French atomic energy commission (CEA) addressed an authorization demand for the definitive shutdown and dismantling of the Siloe reactor. After a technical and administrative instruction of this demand by the French nuclear safety authority (ASN), a project of decree has been presented on July 6, 2004 at the permanent section of the inter-ministry commission of basic nuclear facilities. The commission gave its favourable judgment which is the object of this decree. (J.S.)

Dismantling of nuclear facilities. From a structural engineering perspective

International Nuclear Information System (INIS)

Block, Carsten; Henkel, Fritz-Otto; Bauer, Thomas

2014-01-01

The paper summarizes some important aspects, requirements and technical boundary conditions that need to be considered in dismantling projects in the nuclear sector from a structural engineering perspective. Besides general requirements regarding radiation protection, occupational safety, efficiency and cost effectiveness it is important to take into account other conditions which have a direct impact on technical details and the structural assessment of the dismantling project. These are the main aspects highlighted in this paper: - The structural assessment of dismantling projects has to be based on the as-built situation. - The limitations in terms of available equipment and space have to be taken into account. - The structural assessments are often non-standardized engineering evaluations. A selection of five dismantling projects illustrates the various structural aspects. (orig.)

Stresses in reactor pressure vessel nozzles -- Calculations and experiments

International Nuclear Information System (INIS)

Brumovsky, M.; Polachova, H.

1995-01-01

Reactor pressure vessel nozzles are characterized by a high stress concentration which is critical in their low-cycle fatigue assessment. Program of experimental verification of stress/strain field distribution during elastic-plastic loading of a reactor pressure vessel WWER-1000 primary nozzle model in scale 1:3 is presented. While primary nozzle has an ID equal to 850 mm, the model nozzle has ID equal to 280 mm, and was made from 15Kh2NMFA type of steel. Calculation using analytical methods was performed. Comparison of results using different analytical methods -- Neuber's, Hardrath-Ohman's as well as equivalent energy ones, used in different reactor Codes -- is shown. Experimental verification was carried out on model nozzles loaded statically as well as by repeated loading, both in elastic-plastic region. Strain fields were measured using high-strain gauges, which were located in different distances from center of nozzle radius, thus different stress concentration values were reached. Comparison of calculated and experimental data are shown and compared

Decommissioning of the research nuclear reactor IRT-M and problems connected with radioactive waste

International Nuclear Information System (INIS)

Abramidze, S.P.; Katamadze, N.M.; Kiknadze, G.G.; Saralidze, Z.K.

2000-01-01

The nuclear research reactor IRT-2000 is described, along with modifications and upgrades made over the past three decades. Considerations are outlined which followed a decision to shut-down the reactor and to dismantle it. (author)

Nuclear reactor installation with outer shell enclosing a primary pressure vessel

International Nuclear Information System (INIS)

1975-01-01

The high temperature nuclear reactor installation described includes a fluid cooled nuclear heat source, a primary pressure vessel containing the heat source, an outer shell enclosing the primary pressure vessel and acting as a secondary means of containment for this vessel against outside projectiles. Multiple auxiliary equipment points are arranged outside the outer shell which comprises a part of a lower wall around the primary pressure vessel, an annular part integrated in the lower wall and extending outwards as from this wall and an upper part integrated in the annular part and extending above this annular part and above the primary pressure vessel. The annular part and the primary pressure vessel are formed with vertical penetrations which can be closed communicating respectively with the auxiliary equipment points and with inside the pressure vessel whilst handling gear is provided in the upper part for vertically raising reactor components through these penetrations and for transporting them over the annular part and over the primary pressure vessel [fr

Additional Stress And Fracture Mechanics Analyses Of Pressurized Water Reactor Pressure Vessel Nozzles

International Nuclear Information System (INIS)

Walter, Matthew; Yin, Shengjun; Stevens, Gary; Sommerville, Daniel; Palm, Nathan; Heinecke, Carol

2012-01-01

In past years, the authors have undertaken various studies of nozzles in both boiling water reactors (BWRs) and pressurized water reactors (PWRs) located in the reactor pressure vessel (RPV) adjacent to the core beltline region. Those studies described stress and fracture mechanics analyses performed to assess various RPV nozzle geometries, which were selected based on their proximity to the core beltline region, i.e., those nozzle configurations that are located close enough to the core region such that they may receive sufficient fluence prior to end-of-life (EOL) to require evaluation of embrittlement as part of the RPV analyses associated with pressure-temperature (P-T) limits. In this paper, additional stress and fracture analyses are summarized that were performed for additional PWR nozzles with the following objectives: To expand the population of PWR nozzle configurations evaluated, which was limited in the previous work to just two nozzles (one inlet and one outlet nozzle). To model and understand differences in stress results obtained for an internal pressure load case using a two-dimensional (2-D) axi-symmetric finite element model (FEM) vs. a three-dimensional (3-D) FEM for these PWR nozzles. In particular, the ovalization (stress concentration) effect of two intersecting cylinders, which is typical of RPV nozzle configurations, was investigated. To investigate the applicability of previously recommended linear elastic fracture mechanics (LEFM) hand solutions for calculating the Mode I stress intensity factor for a postulated nozzle corner crack for pressure loading for these PWR nozzles. These analyses were performed to further expand earlier work completed to support potential revision and refinement of Title 10 to the U.S. Code of Federal Regulations (CFR), Part 50, Appendix G, Fracture Toughness Requirements, and are intended to supplement similar evaluation of nozzles presented at the 2008, 2009, and 2011 Pressure Vessels and Piping (PVP

Dual pressurized light water reactor producing 2000 M We

Energy Technology Data Exchange (ETDEWEB)

NONE

2010-10-15

The dual unit optimizer 2000 M We (Duo2000) is proposed as a new design concept for large nuclear power plant. Duo is being designed to meet economic and safety challenges facing the 21 century green and sustainable energy industry. Duo2000 has two nuclear steam supply systems (NSSS) of the unit nuclear optimizer (Uno) pressurized water reactor (PWR) in a single containment so as to double the capacity of the plant. Uno is anchored to the optimized power reactor 1000 M We (OPR1000) of the Korea Hydro and Nuclear Power Co., Ltd. The concept of Duo can be extended to any number of PWRs or pressurized heavy water reactors (PHWR s), or even boiling water reactor (BWRs). Once proven in water reactors, the technology may even be expanded to gas cooled, liquid metal cooled, and molten salt cooled reactors. In particular, since it is required that the small and medium sized reactors (SMRs) be built as units, the concept of Duo2000 will apply to SMRs as well. With its in-vessel retention as severe accident management strategy, Duo can not only put the single most querulous PWR safety issue to end, but also pave ways to most promising large power capacity dispensing with huge redesigning cost for generation III + nuclear systems. The strengths of Duo2000 include reducing the cost of construction by decreasing the number of containment buildings from two to one, minimizing the cost of NSSS and control systems by sharing between the dual units, and lessening the maintenance cost by uniting NSSS. The technology can further be extended to coupling modular reactors as dual, triple, or quadruple units to increase their economics, thus accelerating the commercialization as well as the customization of SMRs. (Author)

Activities in the Czech Republic for reactor pressure components lifetime management

International Nuclear Information System (INIS)

Brumovsky, M.

1994-01-01

The following activities in the Czech republic for reactor pressure components lifetime management are described: upgrading and safety assurance of nuclear power plants (NPP) with reactors of WWER-440/V-230 type, safety assurance of NPPs with reactors of WWER-440/V-213, lifetime management programme of NPPs with WWER-440/V-213 reactors, preparation of start-up of NPPs with WWER-1000/V-320 reactors, preparation of guides for lifetime as well as defect allowability evaluation in main components of primary and secondary circuits. 3 figs

Influence of operating pressure on the biological hydrogen methanation in trickle-bed reactors.

Science.gov (United States)

Ullrich, Timo; Lindner, Jonas; Bär, Katharina; Mörs, Friedemann; Graf, Frank; Lemmer, Andreas

2018-01-01

In order to investigate the influence of pressures up to 9bar absolute on the productivity of trickle-bed reactors for biological methanation of hydrogen and carbon dioxide, experiments were carried out in a continuously operated experimental plant with three identical reactors. The pressure increase promises a longer residence time and improved mass transfer of H 2 due to higher gas partial pressures. The study covers effects of different pressures on important parameters like gas hourly space velocity, methane formation rate, conversion rates and product gas quality. The methane content of 64.13±3.81vol-% at 1.5bar could be increased up to 86.51±0.49vol-% by raising the pressure to 9bar. Methane formation rates of up to 4.28±0.26m 3 m -3 d -1 were achieved. Thus, pressure increase could significantly improve reactor performance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Preventive protection device and method for bottom of reactor pressure vessel

International Nuclear Information System (INIS)

Hayashi, Eisaku; Kurosawa, Koichi; Furukawa, Hideyasu; Morinaka, Ren; Enomoto, Kunio; Otaka, Masahiro; Yoshikubo, Fujio; Chiba, Noboru; Sato, Kazunori.

1995-01-01

In a preventive protection device for improving stresses in reactor structural components by jetting highly pressurized water with cavitation bubbles from a jetting nozzle toward structural components in a reactor pressure vessel, a fixed structure to a CRD housing is provided with a rotational body attached to the structure, a multi joint arm and a jetting nozzle supported to the multi joint arm. The jetting nozzle is disposed at a position where the center of the jetting deviates from the center of the CRD housing. In addition, a monitoring camera is disposed for displaying the target for preventive protection. The state of stresses on a plurality of targets for preventive protection can be improved by the preventive protection device at a fixed position in the bottom of a reactor pressure vessel where housings stand densely, thereby enabling to attain the preventive protection operation easily and rapidly. (N.H.)

User Interface Technology to Reduce Mental Transformations for Tangible Remote Dismantling Simulator

Energy Technology Data Exchange (ETDEWEB)

Hyun, Dongjun; Kim, Ikjune; Lee, Jonghwan; Kim, Geun-Ho; Jeong, Kwan-Seong; Choi, Byung-Seon; Moon, Jeikwon; Choi, Jong-Won [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

High-level radiation of the major components restricts access by human workers, and makes an accident or outage during the dismantling process more difficult to deal with. Since unexpected situations causes waste of budget and an aggravation of safety, the preliminary verification of the dismantling processes and equipment by the tangible remote dismantling simulator is very important. The design optimization of the dismantling processes and equipment is one of the most important objectives of the tangible remote dismantling simulator, as well. This paper proposes a user interface technology to reduce mental transformations for the tangible remote dismantling simulator. At the dismantling process simulation using the tangible remote dismantling simulator, the most difficult work is the remote operation handling the high degrees-of-freedom (DOF) manipulator due to complex mental transformations. The proposed user interface technology reduces mental transformations with constraints using the point projection and direction projection. The test result of the cutting process over the closure head of the RPV demonstrates that the proposed mental transformation reduction technology is operated successfully in the tangible remote dismantling simulator, and lets the operator be easy to control the high DOF manipulator even in the most difficult operation by reducing DOFs to be controlled manually.

User Interface Technology to Reduce Mental Transformations for Tangible Remote Dismantling Simulator

International Nuclear Information System (INIS)

Hyun, Dongjun; Kim, Ikjune; Lee, Jonghwan; Kim, Geun-Ho; Jeong, Kwan-Seong; Choi, Byung-Seon; Moon, Jeikwon; Choi, Jong-Won

2015-01-01

High-level radiation of the major components restricts access by human workers, and makes an accident or outage during the dismantling process more difficult to deal with. Since unexpected situations causes waste of budget and an aggravation of safety, the preliminary verification of the dismantling processes and equipment by the tangible remote dismantling simulator is very important. The design optimization of the dismantling processes and equipment is one of the most important objectives of the tangible remote dismantling simulator, as well. This paper proposes a user interface technology to reduce mental transformations for the tangible remote dismantling simulator. At the dismantling process simulation using the tangible remote dismantling simulator, the most difficult work is the remote operation handling the high degrees-of-freedom (DOF) manipulator due to complex mental transformations. The proposed user interface technology reduces mental transformations with constraints using the point projection and direction projection. The test result of the cutting process over the closure head of the RPV demonstrates that the proposed mental transformation reduction technology is operated successfully in the tangible remote dismantling simulator, and lets the operator be easy to control the high DOF manipulator even in the most difficult operation by reducing DOFs to be controlled manually

Towards the creation of an industrial sector dedicated to nuclear dismantling

International Nuclear Information System (INIS)

Anon.

2015-01-01

In next decades the business of nuclear dismantling is expected to grow exponentially due to the decommissioning of nuclear facilities that will have reached the end of their operating life. Dismantling has 2 main features: dismantling operations on a same site can span decades and dismantling is a new activity in which innovations are likely to appear and may benefit other sectors. In France regional authorities have promoted public-private partnerships in order to make working together small enterprises very specialized in sectors like robotic, laser cutting, waste processing, remote operations... with public laboratories dedicated to nuclear research, and with graduate schools to include dismantling in curriculum and with major industrial operators of the nuclear industry. The aim is the creation of jobs and the building of an industrial sector able to win market shares in the worldwide business of nuclear dismantling. (A.C.)

Reactor coolant pressure boundary leakage detection system

International Nuclear Information System (INIS)

Dissing, E.; Svansson, L.

1980-01-01

This study deals with a system for monitoring the leakage of reactor coolant. This system is based primarily on the detection of the 13 N content in the containment atmosphere. 13 N is produced from the oxygen of the reactor water via the recoil proton nuclear process Hl+016/yields/ 13 N+ 4 He. The generation is therefore independent of fuel element leakage and of the corrosion product content in the water. It is solely related to the neutron flux level in the reactor core. Typical figures for the equilibrium 13 N concentration in the containment atmosphere following a 4 kg/minute coolant leakage are 5 kBq m/sup -3/ and 7 kBq m/sup -3/ for BWR and PWR respectively. These levels are readily measured with a 10 liter Ge(Li) flow detector assembly operated at elevated pressure. 8 refs

Reactor coolant pressure boundary leakage detection system

International Nuclear Information System (INIS)

Dissing, E.; Svansson, L.

1980-01-01

This study deals with a system for monitoring the leakage of reactor coolant. This system is based primarily on the detection of the N13 content in the containment atmosphere. N13 is produced from the oxygen of the reactor water via the recoil proton nuclear process Hl+016/yields/Nl3+He4. The generation is therefore independent of fuel element leakage and of the corrosion product content in the water. It is solely related to the neutron flux level in the reactor core. Typical figures for the equilibrium N13 concentration in the containment atmosphere following a 4 kg/minute coolant leakage are 5 kBq m/sup -3/ and 7 kBq m/sup -3/ for BWR and PWR respectively. These levels are readily measured with a 10 liter Ge(Li) flow detector assembly operated at elevated pressure. 8 refs

Reactor coolant pressure boundary leakage detection system

International Nuclear Information System (INIS)

Dissing, E.; Svansson, L.

1979-08-01

The present paper deals with a system for monitoring the leakage of reactor coolant. This system is based primarily on the detection of the N13 content in the containment atmosphere. N13 is produced from the oxygen of the reactor water via the recoil proton nuclear process H1+016 → N13+He4. The generation is therefore independent of fuel element leakage and of the corrosion product content in the water. It is solely related to the neutron flux level in the reactor core. Typical figures for the equilibrium N13 concentration in the containment atmosphere following a 4 kg/minute coolant leakage are 5 kBq m -3 and 7 kBq m -3 for BWR and PWR respectively. These levels are readily measured with a 10 liter Ge (Li) flow detector assembly operated at elevated pressure. (Auth.)

Methodology of fuel rod design for pressurized light water reactors

International Nuclear Information System (INIS)

Teixeira e Silva, A.; Esteves, A.M.

1988-01-01

The fuel performance program FRAPCON-1 and the structural finite element program SAP-IV are applied in a pressurized water reactor fuel rod design methodology. The applied calculation procedure allows to dimension the fuel rod components and characterize its internal pressure. (author) [pt

Decision support system for the dismantling of building in nuclear facilities

International Nuclear Information System (INIS)

Zeiher, M.

2009-01-01

In case of decommissioning and dismantling the complex structure of nuclear facilities requires a thorough selection of dismantling methods and a detailed operations planning. The decision for an appropriate technology with respect to economic, environmental and radiation protection aspects has to take into account that the different procedural steps are coordinated. Component specific boundary conditions and process parameters have to be considered. A data base was established that includes the process parameters for different dismantling methodologies. The next step is the determination of specific requirements of plant operators and engineers in order to identify the tasks in the frame of the dismantling process. The authors describes the decision support algorithm that allows to enhance the dismantling efficiency.

Method of decommissioning nuclear reactor building by utilizing sea water buyoancy

International Nuclear Information System (INIS)

Iwashima, Sumio; Ogoshi, Shigeru; Kobari, Shin-ichi.

1989-01-01

Upon dismantling nuclear reactor buildings, peripheral yards are excavated and channels leading to sea shore are formed. Since the outer walls of the reactor buildings are made of iron-reinforced concretes, the opening poritons are grouted with concretes to attain a tightly such closed structure that radioactive wastes, etc. in the inside are not flown out upon reactor discommisioning. Peripheral buildings at relatively low level of radiation contaminations are dismantled and withdrawn. The fundations of the nuclear reactor buildings were dug out and jacked to separate base rocks and the reactor buildings. Then, sea water is introduced into the water channels to entirely float up the buildings. A water gate is disposed in the water channel on the side of sea shore to control the level of sea water. The buildings are moved and guided to the sea shore and towed to a site optimum as a permanent storage area and then burried in that place. The operation period for the discommissioning work can greatly be shortened and the radiation dose and the amount of the wastes can be reduced. (T.M.)

Vandellos-I Dismantling nearing completion

International Nuclear Information System (INIS)