Accommodation of helium in PuO2±x and the role of americium

William D. Neilson, Helen Steele, Nikolas Kaltsoyannis, Samuel T. Murphy

Research output: Contribution to journalArticlepeer-review


The high alpha-activity of plutonium dioxide (PuO 2) results in significant ingrowth of radiogenic helium (He) in the aged material. To safely store/dispose PuO 2 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) + U + D3 scheme are used in a point defect model constructed for PuO 2 to predict the method of He incorporation within the PuO 2 lattice. The simulations predict that the preferred incorporation site for He in PuO 2 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 3+ ions it is shown that He accommodation in oxygen vacancy sites will dominate in PuO 2−x as the material ages.

Original languageEnglish
Pages (from-to)8245-8450
JournalPhysical Chemistry Chemical Physics
Issue number14
Publication statusPublished - 18 Mar 2022


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