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Accommodation of helium in PuO

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<mark>Journal publication date</mark>14/04/2022
<mark>Journal</mark>Physical Chemistry Chemical Physics
Volume24
Number of pages6
Pages (from-to)2845-8250
Publication StatusPublished
Early online date18/03/22
<mark>Original language</mark>English

Abstract

The high alpha-activity of plutonium dioxide (PuO ) results in significant ingrowth of radiogenic helium (He) in the aged material. To safely store/dispose PuO or use in applications such as space exploration, the impact of He accumulation needs to be understood. In this work, defect energies obtained using a density functional theory (DFT) + + D3 scheme are used in a point defect model constructed for PuO to predict the method of He incorporation within the PuO lattice. The simulations predict that the preferred incorporation site for He in PuO is a plutonium vacancy, however, the point defect model indicates that helium will be accommodated as an interstitial irrespective of He concentration and across a wide stoichiometric range. By considering the charge imbalance that arises due to incorporation of Am ions it is shown that He accommodation in oxygen vacancy sites will dominate in PuO as the material ages.