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Oral presentation

Distribution measurement at microlevel of Cs chemisorbed compounds onto stainless steel under LWR severe accident

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.

Oral presentation

In situ analysis of solid solution formation of CeO$$_{2}$$ and Gd$$_{2}$$O$$_{3}$$

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$$_{2}$$ and Gd$$_{2}$$O$$_{3}$$ were used as simulating materials of UO$$_{2}$$ and PuO$$_{2}$$, respectively. A shrinkage rate measurement on CeO$$_{2}$$ and Gd$$_{2}$$O$$_{3}$$ 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$$_{2}$$ and Gd$$_{2}$$O$$_{3}$$ 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.

Oral presentation

Development of fuel melting behavior analysis code based on computational fluid dynamics and material science

Yamashita, Susumu; Yoshida, Hiroyuki

no journal, , 

no abstracts in English

Oral presentation

Recent achievements of the fuel safety research at JAEA

Amaya, Masaki

no journal, , 

no abstracts in English

Oral presentation

Optimization study of Ball-Mill using

Yamashita, Kiyoto; Segawa, Tomomi

no journal, , 

no abstracts in English

Oral presentation

R&D on nitride fuel cycle for MA transmutation to enhance safety and economy, 4; Correlation of milling condition and sintered density of nitride fuel surrogate material

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$$_{0.3}$$Zr$$_{0.7}$$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.

Oral presentation

Study for nuclear material quantification in fuel deblis at Fukushima Daiichi Nuclear Power Station

Nomi, Takayoshi; Nagatani, Taketeru; Shiromo, Hideo; Asano, Takashi

no journal, , 

no abstracts in English

Oral presentation

Core and fuel design of BWR with multi-axial fuel shuffling

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.

Oral presentation

Development of melting point measuring device with laser local heating system; Application to measuring nitride sample

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.

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