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Moriyama, Kiyofumi; Nakamura, Hideo; Nakamura, Koichi*
Transactions of the American Nuclear Society, 103(1), p.463 - 464, 2010/11
A computer code, Kiche, was developed at JAEA for the evaluation of the influence of radiolytic volatilization of iodine in the containment of light water reactors during an accident. It solves a chemical kinetics model including water radiolysis, reactions among iodine species, water radiolysis products, and organic compounds. The reactions and rate constants were collected from the literature. The organic iodine production model of Kiche, which was initially based on LIRIC model, was not applicable to low oxygen concentration conditions like inserted containments of BWRs. We modified the model by considering different reaction paths according to the availability of oxygen. The modified model showed improved agreement with our experimental data with various concentrations of organic impurity and oxygen.
Kitano, Akihiro; Okawachi, Yasushi; Kishimoto, Yasufumi*; Hazama, Taira
Transactions of the American Nuclear Society, 103(1), p.785 - 786, 2010/11
The Japanese prototype fast breeder reactor Monju has restarted its operation in May, 2010 after 14-year interruption. This paper summarizes reactor physics experiments in the restart core, for criticality, control rod worth, and isothermal temperature coefficient. The largest change from the previous core, a core before the interruption, is in the contents of 
Pu and Am. The content of Pu has halved and that of Am doubled through the Pu decay during the interruption. The calculation accuracy on the transition from the previous core to the restart core is investigated. The transition is best simulated with JENDL-4 among three nuclear data; JENDL-3.3, JENDL-4, and ENDF/B-VII. The difference mainly appears in Pu fission and Am capture cross sections. It is confirmed that the reactor physics data measured in the Monju restart core is valuable to verify nuclear data of the two nuclides.
Maeda, Shigetaka; Ito, Chikara; Aoyama, Takafumi; Maeda, Yukimoto; Chatani, Keiji
Transactions of the American Nuclear Society, 103(1), p.581 - 582, 2010/11
The experimental fast reactor Joyo of the Japan Atomic Energy Agency is the first liquid sodium fast reactor in Japan. Thirty years of successful operation of Joyo has shown excellent safety and reliability, and has contributed much to the LMFBR development program. Many kinds of irradiation experience have been accumulated to develop the fuels and materials for the prototype reactor Monju and future fast reactors. Accumulated data have been registered with OECD/NEA database with expectation that these data will be widely used. Joyo is presently temporary shutdown because of periodical inspection including in-vessel inspection and repair. After restart, Joyo will play a key role for a wide variety of science and technology fields as fast neutron irradiation bed.
Tachi, Yoshiaki; Wakabayashi, Toshio*
Transactions of the American Nuclear Society, 103(1), p.268 - 269, 2010/11
It is very attractive technique to transmute long-lived fission products such as iodine-129 included in spent fuel by using Fast Reactors (FRs) to minimize environmental burden and toxic risk due to high level waste disposal. Iodine has low melting point (386K) and low boiling points (457K) compared with FR core temperature. Furthermore, it is corrosive against iron based materials. Then, it is the most important issue to search suitable chemical forms for FR core conditions, having high stability at elevated temperature and good compatibility with cladding material. From the viewpoint of melting point, nuclides generation by neutron irradiation, reactivity with stainless steel, easy fabrication method and recyclability, 5 kinds of iodides of CuI, MgI
, YI
, RbI and YI were selected as the candidate chemical form of iodine for transmutation in FR. In order to evaluate stability of the candidate iodides at elevated temperature, TG-DTA of CuI, RbI, BaI and YI were performed. According to TG-DTA results, no significant mass change showed in BaI beyond those temperatures. Mass of CuI, RbI and YI started to be lost severely at the lower temperature than their melting points. Compatibility test between iodides and cladding materials were conducted. Cladding materials in contact with iodides were heated in a capsule filled with pure Ar gas at 873K for 5000h maximum. Results of cross-section observation showed that MgI and YI made pit corrosion on SUS316 and ODS. It appeared that the upper part of the inner surface test capsules with RbI, YI were degraded severely. Based on the experimental results, the most applicable iodide for transmutation by FR is BaI from the viewpoints of stability at elevated temperature and compatibility with cladding material.
Nakai, Satoru; Kaneko, Yoshihisa; Uchihashi, Masaya
no journal, ,