The nuclear magnetic resonance method was used to study diffusion in ZrHx, where x ranged from 1.588 to 1.960 and the structure could be cubic or tetragonal. It was found that the activation energy was essentially independent of the H content of cubic samples (table 197). The pre-exponential factor was equal to 22.5(2-x) x 1012Hz. In the case of the tetragonal phases, the activation energy increased slightly with H content. It was deduced that a very fast channel, for about 3% of the H atoms, was created by the tetragonality. These atomic jumps were associated with a pre-exponential factor which was some 2 orders of magnitude greater than that for the remainder of the H atoms.

NMR Study of Hydrogen Diffusion in Zirconium Hydride. C.Korn, S.D.Goren: Physical Review B, 1986, 33[1], 68-78

Table 198

Diffusivity of H in α-Zr, Zircaloy-2 and Zircaloy-4