Irradiation growth behavior and effect of hydrogen absorption of Zr-based cladding alloys for PWR

PWR用ジルコニウム系合金の照射成長挙動および水素吸収の影響

垣内 一雄 ; 天谷 政樹  ; 宇田川 豊  

Kakiuchi, Kazuo; Amaya, Masaki; Udagawa, Yutaka

In order to understand the dimensional stability of the fuel rod during long-term use in commercial LWRs, an irradiation growth testing in the Halden reactor of Norway was conducted on various fuel cladding materials including the improved Zr alloy. In this paper, the effect of hydrogen, which was absorbed in the cladding tube due to corrosion, on the irradiation growth behavior was evaluated. Comparison between the specimens with or without pre-charged hydrogen revealed that the effect of hydrogen absorption, accelerating irradiation growth, became significant when the hydrogen content exceeded the hydrogen solubility limit in the corresponding irradiation temperature. Analysis based on this understanding derived growth acceleration effect (0.060.01)%/100 ppm, whose denominator is defined as the amount of absorbed hydrogen involved in hydride precipitation under irradiation as a relevant parameter.