Modelling of dissolved H in Ga stabilised δ-Pu

The behaviour of hydrogen in Ga stabilised δ-Pu has been investigated using atomistic computer simulation techniques. We have considered only the solid solution of H in Pu-Ga. H diffusivity in the undamaged material was calculated and was shown to depend on the Ga concentration of the Pu-Ga alloy. Furthermore, localised regions of high Ga concentration within the material were shown to block H diffusion pathways. These are important findings and could allow for the possibility to control H diffusion if it were possible to control the Ga configuration within the system. The interaction of H with simple point defects was also investigated and suggests that H will behave differently in cascade damaged systems compared to undamaged systems. Vacancies were observed to trap any H interstitials that enter their vicinity, while the likelihood of dissociation was very low, effectively reducing the H diffusion coefficient to zero. On the other hand, binding energy calculations show that it is energetically unfavourable for a H interstitial to be close to a Pu interstitial. No long range interaction between H and the single point defects was observed. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.