Chemical interaction between granular BC and 304L-type stainless steel materials used in BWRs in Japan

Shibata, Hiroki ; Sakamoto, Kan*; Ouchi, Atsushi*; Kurata, Masaki 

Chemical interactions between S.S. and BC may lead to the melting of control rods and subsequent relocation of control rod materials in the early stage of severe accident. The liquid products interact with the surroundings such as control rod blades, Zircaloy channel boxes and fuel rods, which may accelerate the fuel bundle degradation. Previous studies on the chemical interactions between S.S. and BC have been performed using the BC powders or pellets. However, almost all of control rods of BWR in Japan consist of granular BC filled in S.S. tubes. In the present study, the chemical reaction tests were carried out using the materials adopted in BWR in Japan, namely granular BC and 304L type S.S. and it was concluded that the kinetics of chemical interaction between S.S. and granular BC is clearly different from that between S.S. and pellet or powder BC.