Hydrogen absorption behavior on zirconium under -radiolysis of nitric acid solution

Ishijima, Yasuhiro ; Ueno, Fumiyoshi  ; Abe, Hitoshi 

Zirconium (Zr) has been used as a structural material at the spent nuclear fuel reprocessing plant in Japan because of its excellent corrosion resistance against nitric acid solution. And the radiolytic hydrogen is known to be generated in the spent nuclear fuel solution. Zr is known to be highly susceptible to hydrogen embrittlement. Therefore, evaluating the radiolytic hydrogen absorption behavior of Zr in nitric acid solution (HNO) is essential. In this study, immersion tests were conducted on Zr in nitric acid solutions under -ray irradiation to evaluate its radiolytic hydrogen absorption behavior. Results showed that hydrogen concentration on Zr increased both in 1-3 mol/L HNO and pure water at 5 and 7 kGy/h after immersion. The amount of hydrogen absorption on Zr under -ray irradiation had a direct correlation with the radiolytic hydrogen generation value in HNO. The results of glow discharge optical emission spectrometry, thermal desorption spectroscopy, and X-ray diffraction result shows that the absorbed radiolytic hydrogen generated a hydride on the surface of Zr.