Oxidation behavior of Zircaloy-2 cladding tube with axial temperature gradient under mixed steam-air atmosphere

Ioka, Ikuo  ; Kato, Hitoshi; Ogawa, Hiroaki  ; Osaka, Masahiko  

When the function of cooling system for a spent fuel pool loses, the spent fuel pin put under vapor and air environment. Oxidization of the spent fuel pin is considered to be the severe conditions, which have axial temperature gradient including an air-water interface. The oxidation behavior of the Zircaloy-2 with axial temperature gradient was investigated. The oxidation test was carried out at 600 C in mixed steam-air atmosphere. The axial temperature gradient was about 100 C/cm. The amount of hydrogen gas was measured during the test, and the oxide film was analyzed. The amount of hydrogen gas decreased to about 100 ppm after increasing rapidly in early stages of the test. No remarkable difference in thickness of the oxide film was observed in this test condition. There was little influence in mixed steam-air atmosphere on oxidation of Zircaloy-2 with temperature gradient.