The formation and persistence of α-UH3 in uranium hydride under conditions relevant to metallic fuel and nuclear waste storage

IF 3.2 2区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Nuclear Materials Pub Date : 2025-08-06 DOI:10.1016/j.jnucmat.2025.156097

Nick Hodge , Hugh Godfrey , Simon Everall , Sarah May , Andrew Diggle , Matthew O’Sullivan , Anna Adamska

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引用次数: 0

Abstract

The formation of uranium hydride is recognised as a hazard during the storage of uranium metal owing to its potentially pyrophoric properties. Uranium hydride exists mainly in the form of cubic trihydride with two crystal structures. Denoted as α-UH₃ and β-UH₃, the two forms of hydride have different chemical properties, with α-UH₃ being the more chemically reactive phase. The formation and persistence of α-UH₃ under conditions relevant to waste storage will likely have a significant bearing on the reactivity of the residual uranium hydride in waste stored in legacy storage facilities. This study has assessed the formation and persistence of α-UH₃ at a range of temperatures. The work has shown that the fraction of α-UH₃ in uranium hydride gradually increases at decreasing formation temperatures. This means that it could potentially be the dominant phase formed under typical waste storage conditions, which, for the purposes of this paper, can be broadly considered to be typically about 25 °C, with uranium containing wastes either submerged under water, dry or drying with air access or damp in sealed containers. Therefore, in some cases, waste may be stored under conditions where a hydrogen atmosphere may be present to some extent. The work has further shown that in the absence of appreciable oxidant, α-UH₃ is stable at 30 °C and 50 °C for at least 100 d and for over 300 d at ambient temperature and pressure. Given the high α-UH₃ fraction at low formation temperatures and the stability of α-UH₃ at low storage temperatures, it is feasible that α-UH₃ could be the dominant phase in any uranium hydride remaining in uranium metal bearing waste. Hence, the properties of α-UH₃ could have a significant bearing on the behaviour of the waste during the planned retrieval and packaging of legacy uranium bearing wastes. These results add significantly to the understanding of uranium hydride behaviour in the context of storage, retrieval and packaging of uranium metal bearing wastes.

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与金属燃料和核废料贮存有关的条件下，α-UH3在氢化铀中的形成和持续

氢化铀的形成被认为是金属铀储存过程中的一种危险，因为它具有潜在的焦性。氢化铀主要以立方三氢化物形式存在，具有两种晶体结构。表示为α-UH3和β-UH3，两种形式的氢化物具有不同的化学性质，α-UH3是化学反应更活跃的相。α-UH3在核废料贮存条件下的形成和持续可能会对遗留贮存设施中核废料中剩余氢化铀的反应性产生重大影响。本研究评估了α-UH3在一定温度下的形成和持久性。研究表明，随着地层温度的降低，氢化铀中α-UH3的含量逐渐增加。这意味着它可能是在典型的废物储存条件下形成的主要相，就本文的目的而言，可以广泛地认为典型的约25°C，含铀废物要么浸没在水中，要么在空气中干燥或在密封容器中潮湿。因此，在某些情况下，废物可能在某种程度上存在氢气氛的条件下储存。研究进一步表明，在没有明显氧化剂的情况下，α-UH3在30°C和50°C环境温度和压力下稳定至少100 d，超过300 d。考虑到α-UH3在低温下的高分数和α-UH3在低温下的稳定性，α-UH3可能是含铀金属废料中剩余的任何氢化铀的主导相。因此，α-UH3的性质可能对遗留含铀废物的计划回收和包装过程中的废物行为有重要影响。这些结果大大增加了对铀金属废料储存、回收和包装过程中氢化铀行为的理解。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Nuclear Materials 工程技术-材料科学：综合

CiteScore

5.70

自引率

25.80%

发文量

601

审稿时长

63 days

期刊介绍： The Journal of Nuclear Materials publishes high quality papers in materials research for nuclear applications, primarily fission reactors, fusion reactors, and similar environments including radiation areas of charged particle accelerators. Both original research and critical review papers covering experimental, theoretical, and computational aspects of either fundamental or applied nature are welcome. The breadth of the field is such that a wide range of processes and properties in the field of materials science and engineering is of interest to the readership, spanning atom-scale processes, microstructures, thermodynamics, mechanical properties, physical properties, and corrosion, for example. Topics covered by JNM Fission reactor materials, including fuels, cladding, core structures, pressure vessels, coolant interactions with materials, moderator and control components, fission product behavior. Materials aspects of the entire fuel cycle. Materials aspects of the actinides and their compounds. Performance of nuclear waste materials; materials aspects of the immobilization of wastes. Fusion reactor materials, including first walls, blankets, insulators and magnets. Neutron and charged particle radiation effects in materials, including defects, transmutations, microstructures, phase changes and macroscopic properties. Interaction of plasmas, ion beams, electron beams and electromagnetic radiation with materials relevant to nuclear systems.