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Journal Articles

Innovation for flexible use of nuclear power in JAEA

Kamide, Hideki; Shibata, Taiju

NREL/TP-6A50-77088 (Internet), p.35 - 38, 2020/09

JAEA Reports

Inspection and repair techniques in the reactor vessel of the experimental fast reactor Joyo; Replacement of upper core structure

Ito, Hiromichi*; Ota, Katsu; Kawahara, Hirotaka; Kobayashi, Tetsuhiko; Takamatsu, Misao; Nagai, Akinori

JAEA-Technology 2016-008, 87 Pages, 2016/05


In the experimental fast reactor Joyo, as a part of the restoration work of a partial dysfunction of fuel handling, the replacement of the upper core structure (UCS) was started from March 2014, and was completed in December 2014. In the jack-up test, the UCS was jacked-up to 1000 mm without significant sodium shearing resistance and interference. In the replacement of the UCS, a procedure was prepared with the use of wire-jack equipment assuming the interference. As a result, with the procedure and wire-jack were effectively functioned, the work was successfully completed.

Journal Articles

Validation of decay heat evaluation method based on FPGS cord for fast reactor spent MOX fuels

Usami, Shin; Kishimoto, Yasufumi; Taninaka, Hiroshi; Maeda, Shigetaka

Proceedings of International Conference on the Physics of Reactors; Unifying Theory and Experiments in the 21st Century (PHYSOR 2016) (USB Flash Drive), p.3263 - 3274, 2016/05

The present paper describes the validation of the new decay heat evaluation method using FPGS90 code with both the updated nuclear data library and the rational extent of uncertainty, by comparing the results of the decay heat measurement of the spent fuel subassemblies in Joyo MK-II core and by comparing with the calculation results of ORIGEN2.2 code. The calculated values of decay heat (C) by FPGS90 based on the JENDL-4.0 library were coincident with the measured ones (E) within the calculation uncertainties, and the C/E ranged from 1.01 to 0.93. FPGS90 evaluated the decay heat almost 3% larger than ORIGEN2.2, and it improved the C/E in comparison with the ORIGEN2.2 code. Furthermore, The C/E by FPGS90 based on the JENDL-4.0 library was improved than that based on the JENDL-3.2 library, and the contribution of the revision of reaction cross section library to the improvement was dominant rather than that of the decay data and fission yield data libraries.

Journal Articles

Development of a fast reactor for Minor Actinides (MAs) transmutation, 3; Evaluation of measurement data with MA transmutation

Sugino, Kazuteru; Takeda, Toshikazu*

Proceedings of 21st International Conference & Exhibition; Nuclear Fuel Cycle for a Low-Carbon Future (GLOBAL 2015) (USB Flash Drive), p.573 - 581, 2015/09

Journal Articles

Analysis of natural circulation tests in the experimental fast reactor JOYO

Nabeshima, Kunihiko; Doda, Norihiro; Ohshima, Hiroyuki; Mori, Takero; Ohira, Hiroaki; Iwasaki, Takashi*

Proceedings of 16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-16) (USB Flash Drive), p.1041 - 1049, 2015/08

Natural circulation is one of the most important mechanisms to remove decay heat in the sodium cooled fast reactors from the viewpoint of passive safety. On the other hand, it is difficult to evaluate plant dynamics accurately under low flow natural circulation condition. In this study, Super-COPD has been validated through the application to the analysis of natural circulation tests in the experimental fast reactor JOYO. Almost all plant components in JOYO including four air-coolers were modeled in Super COPD. Furthermore, the full scale modeling of fuel subassembly was also adopted in this analysis. The natural circulation test after reactor scram from 100 MW full power at JOYO was selected and simulated by Super-COPD. The transient behaviors predicted by Super-COPD showed good agreement with the experimental data.

Journal Articles

Replacement of upper core structure in experimental fast reactor Joyo, 1; Existing damaged upper core structure jack-up test

Ito, Hiromichi; Suzuki, Nobuhiro; Kobayashi, Tetsuhiko; Kawahara, Hirotaka; Nagai, Akinori; Sakao, Ryuta*; Murata, Chotaro*; Tanaka, Junya*; Matsusaka, Yasunori*; Tatsuno, Takahiro*

Proceedings of 2015 International Congress on Advances in Nuclear Power Plants (ICAPP 2015) (CD-ROM), p.1058 - 1067, 2015/05

In the experimental fast reactor Joyo (Sodium-cooled Fast Reactor (SFR)), it was confirmed that the top of the irradiation test sub-assembly had bent onto the in-vessel storage rack as an obstacle and had damaged the upper core structure (UCS). There is a risk of deformation of the UCS and guide sleeve (GS) caused by interference between them unless inclination is controlled precisely. To mitigate the risk, special jack-up equipment for applying three-point suspension was developed. The existing damaged UCS (ed-UCS) jack-up test using the jack-up equipment was conducted on May 7, 2014. As a result of this test, it was confirmed that the ed-UCS could be successfully jacked-up to 1000 mm without consequent overload. The experience and knowledge gained in the ed-UCS jack-up test provides valuable insights and prospects not only for UCS replacement but also for further improving and verifying repair techniques in SFRs.

Journal Articles

Development of a faulty reactivity detection system appling a digital H$$infty$$ estimator

Suzuki, Katsuo; Suzudo, Tomoaki; Nabeshima, Kunihiko

Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(1), p.24 - 33, 2004/03

This paper concerns an application of digital optimal H$$infty$$ estimator to the detection of faulty reactivity in real-time. The detection system, fundamentally based on the reactivity balance method, is composed of three modules, i.e. the net reactivity estimator, the feedback reactivity estimator and the reactivity balance circuit. H$$infty$$ optimal filters are used for these two reactivity estimators, and the nonlinear neutronics are taken into consideration especially for the design of the net reactivity estimator. A series of performance tests of the detection system are conducted by using numerical simulations of reactor dynamics with the insertion of a faulty reactivity for an experimental fast breeder reactor JOYO. The system detects the typical artificial reactivity insertions of 1¢ within a few seconds with the accuracy of 0.1¢, and is satisfactory for its practical use.

JAEA Reports

Post irradiation examination of (U,Pu)C and (U,Pu)N fuels for fast reactors; Destructive examination result of the fuel pins (Joint research)

Iwai, Takashi; Nakajima, Kunihisa; Kikuchi, Hironobu; Nagashima, Hisao; Kimura, Yasuhiko; Matsui, Hiroki; Arai, Yasuo

JAERI-Research 2002-038, 69 Pages, 2003/01


Uranium-plutonium mixed carbide and nitiride fuel pins were fabricated in JAERI and irradiated at fast test rector JOYO based on the JAERI-JNC joint research program. The results of non-destructive and destructive post irradiation examinations cariied out at JNC were reported elsewhere. This report summarizes the results of destructive post irradiation examinations of (U,Pu)C and (U,Pu)N fuel pins carried out at JAERI.

Journal Articles

Weldability of neutron-irradiated type 316 stainless steel

Watanabe, Katsutoshi; Jitsukawa, Shiro; Hamada, Shozo; Kodaira, Tsuneo; Hishinuma, Akimichi

Fusion Engineering and Design, 31, p.9 - 15, 1996/00

 Times Cited Count:6 Percentile:50.36(Nuclear Science & Technology)

no abstracts in English

Oral presentation

Evaluation of $$gamma$$-ray dose rates on the upper core structure of the experimental fast reactor Joyo

Ito, Chikara; Yamamoto, Takahiro; Maeda, Shigetaka; Ito, Hideaki; Sekine, Takashi

no journal, , 

In the experimental fast reactor Joyo, the upper core structure (UCS) was replaced. We have evaluated $$gamma$$-ray dose rates on UCS in order to conduct radiation shielding design of the UCS cask and radiation exposure control in the UCS removal work. The $$gamma$$-ray dose rates was calculated using the QAD-CGGP2R and corrected by the measured in-vessel axial distributions of $$gamma$$-ray dose rate. In order to verify the $$gamma$$-ray dose rate evaluation procedure, we measured spatial distribution of $$gamma$$-ray on the surface of the cask, which contained UCS using plastic scintillating optical fiber (PSF) during the UCS removal work. The calculated PSF output values were approximately twice as large as measured through the UCS. Correcting the calculated $$gamma$$-ray dose rates on the surface of the cask by results of the comparison has shown appropriate $$gamma$$-ray dose rates distribution.

Oral presentation

Restart and future of research reactors, 4; Status of projects to restart of JAEA research reactors

Kugo, Teruhiko

no journal, , 

Status of projects to restart of JAEA research reactors, such as JRR-3, NSRR, STACY, HTTR and JOYO, are presented.

Oral presentation

Study of few-group constant generation methods with Serpent Monte Carlo code based on JOYO MK-I fast reactor data

Szogradi, M.*; Nagaya, Yasunobu

no journal, , 

A new nodal diffusion solver Ants has been developed at VTT for the development of Generation IV reactor concepts. The two-step approach where group constants are generated via Monte Carlo (MC) methods is used for the reactor core analysis. To validate this approach, the JOYO MK-I core published in the International Handbook of Evaluated Reactor Physics Benchmark Experiments was analyzed. The Serpent Monte Carlo code was used to obtain group constants of the JOYO MK-I core. The Serpent few-group cross sections were then used as input data for Ants. Calculations were also carried out with Serpent and the MVP Monte Carlo code for a full-core 3D model to assess the general performance of the code comparing neutron spectrums and power spatial distributions. Results obtained with the 3D Ants JOYO model were compared with the MC results as the first assessment of the nodal diffusion solver with fast system.

Oral presentation

Consultancy Meeting on preparation for the International Workshop on policy and strategy for decommissioning of research reactors & fast reactors and management of spent fuel

Nagaoki, Yoshihiro; Sekine, Takashi

no journal, , 

According to the Backend Roadmap, JAEA is proceeding with the decommissioning of research facilities. Monju is proceeding with defueling work, and Joyo is preparing to restart. Thought Japan is promoting the nuclear fuel cycle, the future power supply has uncertain. Therefore, it is necessary to strategically manage the spent fuel of the fast reactor.

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