The plutonium/hydrogen reaction: The pressure dependence of reaction initiation time

The hydrogen pressure dependence of the initiation time (It) of the plutonium hydriding reaction has been determined over a hydrogen pressure range of 10–1000 mbar for plutonium covered in a dioxide over-layer. The data show that hydriding initiation time is inversely proportional to hydrogen pressure. This observation is consistent with a model of hydriding attack in which the dioxide over-layer acts as a diffusion barrier, controlling the flow of hydrogen to the oxide/metal interface. The low scatter and reproducibility of the experimental data set illustrate the importance of synthesising a reproducible oxide layer prior to determining this experimental parameter.