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Suzuki, Eriko; Ogawa, Hiroaki; Nakajima, Kunihisa; Nishioka, Shunichiro; Osaka, Masahiko; Yamashita, Shinichiro; Kurishiba, Ryoko*; Endo, Takashi*; Isobe, Shigehito*; Hashimoto, Naoyuki*
no journal, ,
To elucidate Cs chemisorption behaviour onto stainless steel under LWR severe accident condition, elemental distribution measurement at microlevel was performed by using XPS and TEM. As a result, it was found that Cs-(Fe)-Si-O compounds, which have different composition, could be distributed.
and GdO
Tsuchimochi, Ryota; Sugata, Hiromasa*; Sunaoshi, Takeo*
no journal, ,
Solid solution reaction of MOX pellet procceds at sintering process, but at what temperature and how fast the reaction proceeds have not been understood. CeO and GdO were used as simulating materials of UO and PuO, respectively. A shrinkage rate measurement on CeO and GdO mixed compact was carried out in the temperature range of 300K to 1923K. The shringage curve has two positive peaks at around 1213K and 1600K. High temperature X-ray diffraction measurements on CeO and GdO mixed powder were carried out at 1213K and 1600K for 240 minutes. The solid solution formation was observed at 1600K, but not at 1213K. It is considered that the first shrinkage region at 1213K was caused by initial sintering and the second region at 1600K was caused by mid-final sintering.
Narukawa, Takafumi
no journal, ,
no abstracts in English
Yamashita, Susumu; Yoshida, Hiroyuki
no journal, ,
no abstracts in English
Amaya, Masaki
no journal, ,
no abstracts in English
Yamashita, Kiyoto; Segawa, Tomoomi
no journal, ,
no abstracts in English
Takaki, Seiya; Takano, Masahide
no journal, ,
Regarding nitride fuel for nuclear transformation of minor actinides, in order to obtain fundamental knowledge for sintering density control by adding pore former, under the various grinding conditions, Dy
Zr
N simulated nitride fuel Sintering experiments were carried out. Although the sintered density of the simulated nitride fuel increases with the increase of the specific surface area of the pulverized powder, it can be confirmed that the sintered density decreases as the strain in the grain increases.
Nomi, Takayoshi; Nagatani, Taketeru; Shiromo, Hideo; Asano, Takashi
no journal, ,
no abstracts in English
Tasaki, Yudai; Yamaji, Akifumi*; Amaya, Masaki
no journal, ,
In breeding core designs with light water, tight lattice fuel bundle design in which the coolant flow area is small is adopted to prevent the neutron moderating. Additionally, the core often consists of MOX fuel and blanket fuel, which aims to irradiate depleted uranium effectively. In preceding study, the concept of "Multi-axial fuel shuffling" has been proposed for a higher breeding core design of supercritical-water cooled reactor (SCWR), in which the core consists of multiple layers of MOX fuels and blanket fuels with independent fuel shuffling for the upper blanket layer where coolant density is lowest. As a result, the SCWR with multi-axial fuel shuffling has shown improvement of breeding performance. The same principle may be applied to BWR, since the coolant density gets low due to developing void fraction. However, the fuel rod included such a core design has two kinds of fuel pellets, and MOX fuel parts tend to get high power peaking. Therefore, it is necessary to investigate and mitigate the fuel maximum temperature and the shear stress of the boundary between MOX and blanket fuel parts which may occur by the difference of PCMI characteristics of two fuel parts. Moreover, it is possible that the cladding outer diameter change especially in MOX fuel parts may impact on the thermal-hydraulics, because the gap between rods is narrow owing to the tight lattice fuel bundle design. This study has shown the improvement of breeding performance of BWR with multi-axial fuel shuffling, and the fuel design which mitigates the above design issues. The cladding outer diameter change doesn't impact on critical heat flux ratio mostly, but depends on pressure drop of the flow channel. Therefore, this result suggests a design issue with respect to the core flow distribution.
Iwasa, Toma
no journal, ,
Minor actinide (MA) transmutation by ADS (accelerator driven system) is studied for volume and radioactivity reduction of high-level radioactive waste. Candidate of the MA transmutation fuel is nitride, and it is important to acquire physical properties of the MA-bearing nitride fuel. Melting point is one of the crucial thermophysical properties, however measuring melting point of nitride fuel is difficult because of its high melting point and high radioactivity. So, this study focus on measuring melting point by combination of laser local heating and measuring spectral emissivity that is able to measure without contact and container. Considering scalability, the measuring system with spectrometer have been constructed. Samples are ZrN as the inert matrix and (Er,Zr)N solid solution as surrogate fuel material. High pressure vessel filled with pure nitrogen gas and preheating by CW laser enabls to measure with minimal oxidation and cracking by thermal shock. Measuring by spectrometer enabls to obtain thermal emission spectrum and calculate spectral radiance of sample.