On the Fate of Tritium in Nickel

Abstract

Uptake, distribution, and release behavior of tritium in Ni was investigated by chemical etching and thermal release rate measurements. Liberated tritium was found to consist almost exclusively of tritiated water. The chronic release rate of tritium from Ni was significantly larger than that from type 316 stainless steel. Depth profiles in specimens that partially lost tritium due to its chronic release into vacuum, air or a stream of argon could be reproduced by a one-dimensional diffusion model using best fit diffusion coefficients. Values of the best-fit diffusion coefficients at 298 K were found to be independent from the ambient into which tritium was released. The average diffusion coefficient from all measurements at 298 K, i.e. (2.7 ± 1.3) × 10-10 [cm2/s] was in line with diffusion coefficients calculated from literature data at the same temperature. Hence, the diffusion model constitutes a useful tool for the prediction of tritium bulk depth profiles in Ni during chronic release (CR).