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

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

doi:10.1039/d1cp05570d

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

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

Computational and Theoretical Chemistry

Research output: Contribution to journal › Article › peer-review

Abstract

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 language	English
Pages (from-to)	8245-8450
Journal	Physical Chemistry Chemical Physics
Volume	24
Issue number	14
DOIs	https://doi.org/10.1039/d1cp05570d
Publication status	Published - 18 Mar 2022

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title = "Accommodation of helium in PuO2±x and the role of americium",

abstract = "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.",

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AU - Neilson, William D.

AU - Steele, Helen

AU - Kaltsoyannis, Nikolas

AU - Murphy, Samuel T.

PY - 2022/3/18

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AB - 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.

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

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