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JAEA Reports

Prototype fast breeder reactor Monju; Its history and achievements

Tsuruga Comprehensive Research and Development Center

JAEA-Technology 2019-007, 159 Pages, 2019/07


This report summarizes the history and achievements of the prototype fast breeder reactor Monju. The development of Monju started in 1968 as a prototype reactor following the experimental fast reactor Joyo. The development covers all the activity related to the fast reactor; plant design, mockup tests, construction, operation, and plant management. This report summarizes the history and achievements for 11 technical areas: history and principal achievements, design and construction, operation test, plant safety, core physics, fuel, plant system, sodium technology, materials and mechanical design, plant management, and trouble management.

Journal Articles

Analytical study on safety margins against significant core damage during loss-of-heat-removal-system events in a sodium-cooled fast reactor

Fukano, Yoshitaka

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 9 Pages, 2017/04

Loss-of-heat-removal-system (LOHRS) events are identified as some of most dominant severe accident sequences in a sodium-cooled fast reactor. Safety margins against significant core damage in LOHRS events were therefore studied in this paper assuming large fuel-cladding gap and fuel cladding failure. It was clarified through analyses by the developed code that neither fuel melting nor further mechanical pin failure occurs owing to large fuel-cladding gap and fuel cladding failure. It was therefore concluded that large safety margins against significant core damage are provided during LOHRS events. These results will be effectively used in formulating the safety criteria for severe accidents or beyond-design-basis-accidents as one of the supporting evidences to be seriously considered.

JAEA Reports

Proceedings of the Workshop on Reactor Safety Research, Focusing on the Integrity of Aged Components; March 17, 2003, Tokai Research Establishment, Tokai-mura

Hidaka, Akihide; Suzuki, Masahide

JAERI-Conf 2003-014, 178 Pages, 2003/09


The Workshop on Reactor Safety Research focusing on the integrity of aged components was held at the Tokai Research Establishment on March 17, 2003. The purpose of the Workshop was to obtain useful information to proceed with the reactor safety research in future and to resolve the issues on the integrity evaluation of aged components through the discussions followed by the presentations on the results of the research at JAERI on all the research subjects assigned to JAERI in the Five-Year Program of Safety Research for Nuclear Installations established by the Nuclear Safety Commission, and on those of the studies at JAERI on the integrity of core shrouds of BWR plants. Thirty-eight people from outside JAERI including the press such as Nihon Television Network Corporation and Shin-Ibaraki Shinbun and fifty-seven people from JAERI attended the Workshop. This proceeding compiles all the viewgraphs presented in the workshop, the opinions of participants for forum and the answers, and summary of questionnaire on workshop.

JAEA Reports

JAEA Reports


JNC TN1400 2001-002, 172 Pages, 2001/01


no abstracts in English

JAEA Reports

Report of the review committee on evaluation of the R&D subjects in the field of nuclear safety research

Research Evaluation Committee

JAERI-Review 2000-021, 36 Pages, 2000/09


no abstracts in English

JAEA Reports

Studies on sodium cooled fast breeder reactor

Nibe, Nobuaki; Shimakawa, Yoshio; ; ; ; ;

JNC TN9400 2000-074, 388 Pages, 2000/06


Large sized sodium-cooled fast breeder reactors of large-size are being studied and have been operated in Japan and many countries. ln this feasibility study, evaluation was made on technical feasibinty for design concepts or 1 loop type and 3 pool types, specially from the viewpoint of improvement of economical competence. The design concepts include the ideas of cost reduction measures such as large-scaled components, reduction of loop number and integration of components on the basic of utilization of sodium characteristics. From the results of the evaluation, it may be possible for all the concepts to attain the economical target of 200 thousands yen per kilowatt, though further confirmation should be made for technical feasibility of those concepts. ln addition, the following items were listed up as further cost-reduction measures. (1)Higher temperature cooling system and steam cycle efficiency (2)Shortening of construction term (3)Reduction of safety systems by using measuring instruments with high performmce (4)Adoption of SG-ACS

JAEA Reports

Investigation of molten salt fast breeder reactor

; ; ; ;

JNC TN9400 2000-066, 52 Pages, 2000/06


Phase I of feasibility studies on commercialized fast reactor system is being peformed for two years from Japanese Fiscal Year 1999. In this report, results of the study on fluid fuel reactors (especialiy a molten salt fast breeder reactor concept) are described from the viewpoint of technical and economical concerns of the plant system design. ln JFY1999, we have started to investigate the fluid fuel reactors as alternative concepts of sodium cooled FBR systems with MOX fuel, and selected the unique concept of a molten chloride fast, breeder reactor, whose U-Pu fuel cycle can be related to both light water reactors and fast breeder reactors on the basis of present technical data and design experiences. We selected a preliminary composition of molten fuel and conceptual plant design through evaluation of technical and economical issues essential for the molten salt reactors and then compared them with reference design concepts of sodium cooled FBR systems under limited information on the molten chloride fast breeder reactors. The following results were obtained. (1)The molten chloride fast breeder reactors have inherent safety features in the core and plant performances, ad the fluid fuel is quite promising for cost reduction of the fuel fabrication and reprocessing. (2)On the other hand, the inventory of the molten chloride fuel becomes high and thermal conductivity of the coolant is inferior compared to those of sodium cooled FBR systems, then, the size of main components such as lHX's becomes larger and the amount of construction materials is seems to be increased. (3)Furthermore economical vessel and piping materials which contact with the molten chloride salts are required to be developed. From the results, it is concluded that further steps to investigate the molten chloride fast breeder reactor concepts are too early to be conducted.

JAEA Reports

Annual report on the environmental radiation monitoring around Tokai reprocessing plant FY 1999

; Shinohara, Kunihiko; ; ; ; Takeyasu, Masanori;

JNC TN8440 2000-007, 141 Pages, 2000/06


Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed since 1975, based on "Safety Regulations for the Tokai Reprocessing Plant, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitants due to the radioactivity discharged from the plant during April 1999 to March 2000. Appendices present comprehensive information, such as monitoring program, monitoring results, meteorological data and annual discharges from the plant.

JAEA Reports


JNC TN4420 2000-009, 11 Pages, 2000/06



JAEA Reports

Study on optimaI vertical isolation characteristics


JNC TN9400 2000-060, 168 Pages, 2000/05


Optimal vertical isolation characteristics were studied for the structural concept of vertical seismic isolation system, which uses a common deck and a set of large coned dish springs. Four kinds of earthquake wave and three kinds of artificial seismic wave were used. The earthquake response analysis of a base isolated building was carried out considering some ground conditions and some vertical vibration characteristics of the building isolator. Floor response and acceleration time history at the vertical isolation level were arranged. Using the acceleration time history as a seismic input, the earthquake response analysis of the vertical isolation system according to single degree of freedom model was carried out. Linear analysis and non-linear analysis were made. ln the linear analysis, vertical isolation frequency was examined within 0.8 to 2.5 Hz, and damping ratio was examined within 2 to 60%. ln the non-linear analysis, it was examined within vertical isolation frequency 0.5 to 5Hz, which depended only on the rigidity of the coned disk spring, rigidity ratio of the damping devise 1 to 20 and yield seismic intensity of the damping devise 0.01 to 0.2. As the optimal vertical isolation characteristics of the system, the criterion of largest relative displacement, maximum acceleration and maximum value of the floor response acceleration between 5 to 12Hz was set, the combination region of the appropriate parameter were examined. ln case of largest relative displacement 50mm, acceleration response magnification of 0.75, floor response magnification of 0.33 were used as a criterion, from the result of the linear analysis, vertical frequency was set at 0.8 to l.2 Hz, and by combining the damping ratio over 20 %, it was proven that appropriate vertical isolation characteristics were obtained. The result of the non-linear analysis showed that the combination of the coned disk spring of vertical frequency 0.8 to 1.0 Hz and the damping element of rigidity ...

JAEA Reports

Study of safety aspects for pyrochemical reprocessing systems


JNC TN9400 2000-051, 237 Pages, 2000/04


In this study, we have proposed the concept of safety systems (solutions of safety problems) in pyrochemical reprocessing systems (lt consists of pyrochemical reprocessing methods and the injection casting process for the metal fuel fabrication, or vibro-packing process for the oxide fuel fabrication.) which has different concept from the existing PUREX reprocessing method and pellet fuel fabrication process. And we performed its safety evaluations. FoIlowing the present Japanese safety regulations for reprocessing facilities, we pointed out functions, design requirements and equipments relating to its safety systems and picked up subjects. For the survey of safety evaluations, we first selected anticipated events and accident events, and second by evaluated 6the correspondence of the limitation of the public exposure to the accidents above, by using two parameters, the safety design parameter (the filter performance to confine radioactive matelials) and the leak inventory of radioactivities, and last by picked up its problems. ln addition to the above evaluations we performed basic criticality analyses for its systems to utilize these results for the design and evaluation of the criticality safety management system. Thus this study specified the concept of safety systems for pyrochemical reprocessing processes and then issues in order to establish safety design policies (matters which must consider for the safety design) and guides and to advance more definite safety design.

JAEA Reports

An Evaluation study of measures for prevention of Re-criticality in sodium-cooled large FBR with MOX fuel

JNC TN9400 2000-038, 98 Pages, 2000/04


As an effort in the feasibility study on commercialized Fast Breeder Reactor cycle systems, an evaluation of the measures to prevent the energetic re-criticality in sodium-cooled large MOX core, which is one of the candidates for the commercialized reactor, has been performed. The core disruptive accident analysis of Demonstration FBR showed that the fuel compaction of the molten fuel by radial motion in a large molten core pool had a potential to drive the severe super-prompt re-criticality phenomena in ULOF sequence. ln order to prevent occurrence of the energetic re-criticality, a subassembly with an inner duct and the removal of a part of LAB are suggested based on CMR (Controlled Material Relocation) concept. The objective of this study is the comparison of the effectiveness of CMR among these measures by the analysis using SIMMER-III. The molten fuel in the subassembly with inner duct flows out faster than that from other measures. The subassembly with inner duct will work effectively in preventing energetic re-criticality. Though the molten fuel in the subassembly without a part of LAB flows out a little slower, it is still one of the promising measures. However, the UAB should be also removed from the same pin to prevent the fuel re-entries into the core region due to the pressurization by FCl below the core, unless it disturbs the core performance. The effect of the axial fuel length of the center pin to CMR behavior is small, compared to the effect of the existence of UAB.

JAEA Reports

ICONE-8 participation and investigation report of dry process in Argonne National Laboratory (ANL), USA

; Washiya, Tadahiro;

JNC TN8420 2001-009, 48 Pages, 2000/04


ICONE(International Conference on Nuclear Engineering) is an international conference on nuclear chemical engineering held among the United States, Japan and Europe, and ICONE8 (the 8th time of the conference) was held at Baltimore, USA on April 2 to 6, 2000. The authors of this paper reported the latest information on the reprocessing technology in the following session of the conference and audited the panel discussion and the technical report of the dry reprocessing technology etc. in the conference. (1)Investigation of Safety Evaluation Method and Application to Tokai Reprocessing Plant (TRP) in session of Track-5 "Non-reactor Safety and Reliability" (Nakamura) (2)Structural Improvement on the continuous rotary dissolver in session of Track-9 "Spent Nuclear Fuel and Waste Processing" (Washiya) (3)Development of Evaporators Made of Ti-5% Ta Alloy and Zr - Endurance Test By Mock-Up unit" in session of Track-2 "Aging and Modeling of Component Aging, Including corrosion of Metals and Welds.. passivation, and passive films" (Takata) At the conference, about 650 people participated from the United States, Japan, France, Canada and others, about700 research announcements, 7 keynote lecture and 8 panel discussion were done, flourishing with many participants. Moreover, as the conference was held in the year of 2000, the evaluation of this century and the direction of the next century of nuclear energy were discussed. After the conference, authors visited Argonne National Laboratory (ANL-E, ANL-W) and exchanged information concerning dry process with researchers of ANL-E and ANL-W, visiting ANL facilities. It was very significant to be able to acquire the information on the dry process developed in ANL and realize the device scale and the development environment, etc. and acquire technical information in detail which would not be able to obtain by engineering data, exchanging information with ANL engineers directly. It is suggested to be very valuable that the ...

JAEA Reports

Criticality safety evaluation in Tokai reprocessing plant

Shirai, Nobutoshi; ; ; Shirozu, Hidetomo; Sudo, Toshiyuki; Hayashi, Shinichiro;

JNC TN8410 2000-006, 116 Pages, 2000/04


Criticality limits for equipments in Tokai Reprocessing Plant which handle fissile material solution and are under shape and dimension control were reevaluated based on the guideline No.10 "Criticality safety of single unit" in the regulatory guide for reprocessing plant safety. This report presents criticality safety evaluation of each equipment as single unit. Criticality safety of multiple units in a cell or a room was also evaluated. The evaluated equipments were ones in dissolution, separation, purification, denitration, Pu product storage, and Pu conversion processes. As a result, it was reconfirmed that the equipments were safe enough from a view point of criticality safety of single unit and multiple units.

JAEA Reports


Koshizuka, Seiichi*; *; Okano, Yasushi; *; Yamaguchi, Akira

JNC TY9400 2000-012, 91 Pages, 2000/03


no abstracts in English

JAEA Reports

Development of JOYO plant operation management expert Tool (JOYPET)

; Terano, Toshihiro; ; ;

JNC TN9410 2000-004, 30 Pages, 2000/03


The Operation and Maintenance Support Systems for JOYO are being developed, with the aim of ensuring the stable and safe operation of JOYO and improving operational reliability of future FBR plants. Plant Operation Management Expert Tool named JOYPET had been developed as one of the Operation and Maintenance Support Systems, which helps plant operation management. The following functions were developed and applied. (1)Papers management (Plant status management) function for maintenance activities (2)Isolation management support function for plant operation (3)Automatically drawing function of plant operation schedule (4)Isolation judgment function for plant operation By use this system, the plant management of JOYO was able to improved reliability and reduced manpower.

JAEA Reports

Examination of safety design guideline; Safety objective and elimination of re-criticality issues

; ; *;

JNC TN9400 2000-043, 23 Pages, 2000/03


ln the feasibility study on commercialized fast breeder reactor (FBR) cycle systems conducted in JNC, it is required for candidate FBR plants that the level of safety should be enhanced so as to assure: (1)Comparative or superior safety level to that of light water reactors (LWRs), and (2)releaf of the public from anxiety about potential nuclear hazard. Adopting Passive safety characteristics is one of the measures. To attain the above safety objective, we considered implication of the basic safety principles for nuclear power plants that were created by the international nuclear safety advisory group of IAEA. The way to relieve from the anxiety was also taken into account. Then a definite safety objective was set from the standpoint of prevention of core disruptive accident (CDA). Furthermore, as a definite safety goal relating to reactor coresafety, elimination of re-criticality issues under CDA was set by considering characteristics of FBR in comparison with those of LWR. To examine measures for elimination of re-criticality issues, we developed a quick method to estimate possibility of re-criticality under CDA, by drawing a map about criticality characteristics under CDA in various degraded cores. Then hopeful measures were proposed for elimination of re-criticality issues in sodium-cooled FBR with mixed-oxide fuel. Molten fuel discharge behavior of their measures was preliminarily analyzed. We concluded that discharge capability of "a subassembly with an internal duct" was effective, and that "partial removal of axial blanket" was also effective as one of the measures though it has small effect on core performance.

JAEA Reports

Improvement of DYANA; The Dynamic analysis program for event transition

Tamura, Kazuo*; Iriya, Yoshikazu*

JNC TJ9440 2000-004, 22 Pages, 2000/03


In the probabilistic safety assessment(PSA), the fault tree/event tree technique has been widely used to evaluate accident sequence frequencies. However, event tansition which operators actually face can not be dynamically treated by the conventional technique. Therefore, we have made the dynamic analysis program(DYANA) for event transition for a liquid metal cooled fast breeder reactor. In the previous development, we made basic model for analysis. However, we have a probrem that calculation time is too long. At the current term, we made parallelization of DYANA usig MPI. So we got good performance on WS claster. It performance is close to ideal one.

JAEA Reports

Analyses of transient plant response under emergency situations (2)

*; *

JNC TJ9440 2000-002, 90 Pages, 2000/03


In order to support development of the dynamic reliability analysis program DYANA, analyses were made on the event sequences anticipated under emergency situations using the plant dynamics simulation computer code Super-COPD. In this work 9 sequences were analyzed and integrated into an input file for preparing the functions for DYANA using the analytical model and input data which developed for Super-COPD in the previous work. These sequences could not analyze in the previous work, which were categorized into the PLOHS (Protected Loss of Heat Sink) event.

177 (Records 1-20 displayed on this page)