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Pshenichnikov, A.; Yamazaki, Saishun; Nagae, Yuji; Kurata, Masaki
no journal, ,
Nakajima, Kunihisa; Nishioka, Shunichiro; Suzuki, Eriko; Miradji, F.; Osaka, Masahiko
no journal, ,
Radioactive cesium (Cs) localized in the upper region of reactor pressure vessel (RPV) is one of the major concerns, especially in the case of the fuel debris retrieval accessing from top of the RPV. For estimation of amount of Cs chemisorbed onto structure materials, Cs chemisorption model is developed and incorporated into present severe accident codes. However, this chemisorption model cannot accurately reproduce experimental results. Therefore, this study elucidates essential factors influencing the Cs chemisorption behavior and construct the Cs chemisorption model considering these factors. It was found that this model can more accurately reproduce not only our experimental results but also the results used to construct the existing chemisorption model.
Imoto, Jumpei; Miwa, Shuhei; Osaka, Masahiko
no journal, ,
The chemical reactions for release of B from Fe-B and Zr-B compounds formed in the BWR control blade melts at severe accident in light water reactor were experimentally estimated by thermal analysis and X-ray diffraction analysis. For the Zr-B compounds, it was found that B was released via only B
O
formed by oxidation. On the other hand, for the Fe-B compounds, it was found that B were released via two kinds of B oxides, BO and stable Fe-B-O compounds.
Sudo, Ayako; Mizusako, Fumiki*; Hoshino, Kuniyoshi*; Sato, Takumi; Nagae, Yuji; Kurata, Masaki
no journal, ,
Miwa, Shuhei; Nakajima, Kunihisa; Miyahara, Naoya; Nishioka, Shunichiro; Suzuki, Chikashi; Suzuki, Eriko; Horiguchi, Naoki; Imoto, Jumpei; Liu, J.; Miradji, F.; et al.
no journal, ,
We have been conducting the fundamental study on fission product (FP) chemistry under severe accident (SA) conditions. The objective is to construct the FP chemistry database and to improve FP chemistry model for the improvement of source term evaluation technology. We have established the technical basis, such as experimental set-up and analysis tool, for the evaluation of FP chemistry in SA conditions. Fundamental knowledges on the effects of boron on the cesium and iodine chemistry were also obtained.
Sato, Takumi; Hirata, Naoya*; Oikawa, Katsunari*; Nagae, Yuji; Kurata, Masaki
no journal, ,
Macroscopic segregation of molten core and melt components occurs with slow cooling rate in the accident of Fukushima Daiichi Nuclear Power Plants. In this study, solidification and microscopic segregation are simulated with the Scheil model and thermal properties calculated by Thermo-calc in order to investigate an influence of cooling conditions on macroscopic segregation. A macroscopic segregation behaviour has been calculated for UO-ZrO-FeO system, which are major oxides of molten core materials in various conditions. According to calculated results, UO and ZrO were concentrated in initial solidification area. On the other hand, FeO was strongly concentrated in later solidification area. FeO was significantly segregated because FeO does not be dissolved in UO and ZrO. In addition, macroscopic segregation tends to become stronger in the conditions of slow solidification rate and fast velocity of solidification interface.
Yamazaki, Saishun; Pshenichnikov, A.; Pham, V. H.; Nagae, Yuji; Kurata, Masaki
no journal, ,
no abstracts in English