Corrosion behavior and mechanical property of spent fuel cladding tube immersed in warm artificial seawater

Motooka, Takafumi; Suzuki, Kazuhiro; Suzuki, Miho; Toyokawa, Takuya ; Kimura, Yasuhiko

Spent fuels were stored in the spent fuel pool (SFP) at the Fukushima Daiichi Nuclear Power Plant. Seawater was injected into SFP to cool spent fuels for emergency measure in the Fukushima Daiichi Nuclear Accident. Seawater can cause local corrosion. The purpose of this study is to investigate the effect of seawater on corrosion behavior and mechanical property of the spent fuel cladding. We immersed short spent fuel cladding tubes (50 GWd/t) in artificial seawater at 353 K for 300 h and conducted visual, metallographic and strength examinations of the tubes after immersion. Visual and metallographic examination indicated that warm seawater little affected the corrosion behavior of the spent fuel cladding. Black oxides formed on the surface of the cladding during the reactor operation were observed. No local corrosion and crack were observed. Ultimate tensile strength (UTS) and 0.2% yield strength (0.2%YS) of tubes with and without immersion in artificial seawater at 353 K for 300 h were measured. The strength of immersed tube was comparable to that of non-immersed tube. The results suggest that the seawater injection little affects on corrosion behavior and mechanical property of the spent fuel cladding.