Chemical interaction between Sr vapor species and nuclear reactor core structure

Abstract

ABSTRACT The distribution of Sr in the reactor during the Fukushima Daiichi Nuclear Power Station (1 F-NPS) accident would be influenced by the chemical interaction of Sr vapor species with the core structure materials of the internal reactor and the fuel cladding, such as stainless steel (SS) and Zircaloy (Zry) cladding. The chemical interactions between Sr and Zry and between Sr and SS have been described. Chemical interaction tests have been performed to investigate the chemical interaction behavior under possible severe accident conditions. The tests have been conducted up to 1523 K under steam atmosphere. It was confirmed that Sr–Zr–O and Sr–Si–O compounds were formed through two kinds of chemical interactions: gas–solid chemical interaction and liquid–solid chemical interaction. The gas and liquid species of Sr are in good contact with the solid Zry and SS to form the Sr–Zr–O and Sr–Si–O compounds, respectively. Sr was deposited onto the Zry and SS surfaces, leading to the formation of the fission product chemical species. Thus, this study highlights the possibility that Sr was deposited and retained in the core structure where the temperature was elevated during the 1 F-NPS accident.