Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Di Lemma, F. G.; Yamashita, Shinichiro; Nakajima, Kunihisa; Takada, Juntaro; Osaka, Masahiko; Nagase, Fumihisa
no journal, ,
Fission products chemisorption on reactor structural materials is an important phenomenon to be considered following an accident, as it can lead to retention of fission products in the containment, affecting the radioactive release to the environment and reactor decommissioning. The knowledge acquired from this study could help improve the models for cesium(Cs) chemisorption and could be applied to evaluate the distribution and properties of Cs deposits in the Fukushima-Daiichi Nuclear Power Plant, providing guidance for its decommissioning. Our studies were performed vaporizing CsOH over stainless steel samples, varying experimental parameters, such as temperature (800-1000
C) and atmosphere (H
/Ar, H/HO/Ar). Sample surfaces were analyzed by SEM/EDX, XRD to evaluate the deposit microstructure and chemical composition. The EDX characterization results demonstrate a congruent distribution between Cs and Si, and the XRD patterns indicate the formed Cs compound as CsFeSiO
. These results show the importance of the presence of impurities in stainless steel, affecting the formation of stable Cs deposits.
Yamashita, Susumu; Tokushima, Kazuyuki; Yoshida, Hiroyuki; Kurata, Masaki
no journal, ,
To simulate each process of the core melt progression in detail and contribute the improvement of severe accident analysis codes, we have performed the melt relocation experiments by using simplified fuel support pieces of the BWR. In addition, we are developing a numerical simulation code, JUPITER, to simulate the melt relocation in a fuel assembly scale. In this study, the JUPITER was applied to numerical simulations of the melt behavior of the complicated fuel support structures and the melt relocation experiment. As a result, the JUPITER is able to simulate melt relocation behavior in the complicated structures stably, and showed good agreement with the experimental results qualitatively. Therefore, it was confirmed that the JUPITER has potential to provide accurate understanding of the melt relocation behavior. In the near future, in order to simulate the more realistic behavior of the melt relocation, we will implement the eutectic reaction model to the JUPITER and also proceed the experimental analysis.