Neilson William D, Steele Helen, Kaltsoyannis Nikolas, Murphy Samuel T
Engineering Department, Lancaster University, Bailrigg, Lancaster, LA1 4YW, UK.
Sellafield Ltd., Sellafield, Cumbria, CA20 1PG, UK.
Phys Chem Chem Phys. 2022 Apr 6;24(14):8245-8250. doi: 10.1039/d1cp05570d.
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.
二氧化钚（PuO₂）的高α活性会导致老化材料中产生大量的放射性氦（He）。为了安全地储存/处置PuO₂或用于太空探索等应用，需要了解氦积累的影响。在这项工作中，使用密度泛函理论（DFT）+D3方案获得的缺陷能量被用于为PuO₂构建的点缺陷模型中，以预测氦在PuO₂晶格中的掺入方式。模拟结果预测，He在PuO₂中的首选掺入位置是钚空位，然而，点缺陷模型表明，无论He浓度如何以及在很宽的化学计量范围内，氦都将作为间隙原子存在。通过考虑由于掺入镅离子而产生的电荷不平衡，结果表明，随着材料老化，氧空位处的氦容纳将在PuO₂中占主导地位。
