A simple model for hydrogen re-distribution in zirconium-lined fuel claddings

A simple model of hydrogen diffusion and hydride precipitation was developed to estimate the radial re-distribution of hydrogen in zirconium-lined Zircaloy-2 claddings for light water reactors. Numerical calculation based on the model agreed well with experimental data and clearly showed that a slight difference of the terminal solid solubility of hydrogen in the two materials caused a significant flow of hydrogen from Zircaloy-2 to zirconium during slow cooling. The model would also evaluate the hydrogen distribution in the claddings of which the terminal solid solubility is not uniform.