Research on fission product chemistry for FP release and transport behavior

Osaka, Masahiko  ; Miwa, Shuhei  ; Yamashita, Shinichiro   ; Takai, Toshihide  ; Nakajima, Kunihisa  ; Furukawa, Tomohiro  ; Nagase, Fumihisa 

Fission product (FP) chemistry under the LWR severe accident (SA) conditions should be deeply understood for more accurate evaluation of FP release and transport behavior, which can lead to reduction of uncertainty in the evaluation of source term. This paper describes the contents of research program that is focused on the FP chemistry. Results of the FP chemical form just after release from fuel by a chemical equilibrium calculation considering dependences of release kinetics for related elements showed that dominant vapor species have changed according to the atmospheres and Cs-B-O species became dominant in the presence of BC. As for the Cs-chemisorption behavior, it was found by a literature review that resultant compounds formed by the Cs-chemisorption onto the SS could be divided into two categories, Cs-Cr-O and Cs-Si-O compounds.