Transport mechanism of hydrogen through oxide film formed on zircaloy-4

The diffusion behavior of hydrogen in the oxide films of zircaloy-4 specime ns containing different size of Zr(Fe,Cr)(2) precipitates was examined. In the case of the specimen containing fine precipitates, hydrogen diffused un iformly through the zirconium oxide phase. The diffusion coefficient was 2 . 10(-21) m(2) . s(-1) at room temperature and 6 . 10(-19) m(2) . s(-1) at 673 K. The transport rate of hydrogen in the oxide film of the specimen con taining coarse precipitates was significantly higher than that of the speci men containing fine ones at both room temperature and 673 K.