Aging effect for hydrogen embrittlement behavior of Ta/Zr explosive joint

Nakabachi, Kaito*; Yokoyama, Kenichi*; Ishijima, Yasuhiro ; Ueno, Fumiyoshi  ; Abe, Hitoshi 

The effects of thermal aging on hydrogen embrittlement behavior were investigated for Zr/Ta/SUS explosive joints used in spent nuclear fuel reprocessing plants, especially at the Zr/Ta interface, which is considered to be susceptible to hydrogen embrittlement. The results showed that brittle fracture occurred at the Zr/Ta interface when the hydrogen concentration of Ta was over 20 ppm, and the ductility of the specimens with such hydrogen concentration was recovered when the hydrogen concentration of Ta decreased below 10 ppm by thermal aging at 300C for 1000 hr, while the hydrogen concentration was reduced to The ductility of the Ta/Zr interface was not recovered without significant decrease in hydrogen concentration. These results suggest that the hydrogen concentration in Ta at the Ta/Zr interface affects the hydrogen embrittlement behavior of the explosion joint and that the hydrogen state changes with thermal aging.