Continuum-mechanics-based multi-scale modeling of fission gas swelling and release coupling behaviors for UO2 fuels

IF 2.8 2区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Nuclear Materials Pub Date : 2025-03-15 DOI:10.1016/j.jnucmat.2025.155757

Jing Zhang , Feng Yan , Shurong Ding

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Abstract

Under the extreme in-pile environments, gaseous fission products continuously accumulate within nuclear fuels, causing macroscopic fuel swelling and fission gas release. Fission gas swelling and release effects are coupled to each other, related to the diffusion behavior of fission gas atoms within fuel grains. With the evolution of bubbles, the fuels transform into porous structures, degrading their macroscopic thermo-mechanical properties and thereby affecting the overall thermo-mechanical behaviors of the fuel elements. Conducting multi-scale modeling studies on the coupling behaviors of fission gas swelling and release, and achieving accurate predictions of these behaviors, are essential scientific problems and important concerns in reactor engineering design. In this study, the macroscopic volume changes and fission gas release behaviors of porous fuels are considered to be associated with the diffusion of fission gas atom, the growth of inter-granular bubbles, grain recrystallization effects and the creep deformations of the solid skeleton. By considering the contributions of bubble internal pressure, surface tension and external hydrostatic pressure, a multi-scale model describing fission gas swelling and release coupling behaviors is established based on continuum mechanics theory. This model is validated using abundant experimental results. Furthermore, the underlying mechanisms of fission gas swelling and release coupling behaviors are revealed. It is found that the creep deformation of the surrounding skeleton is the primary contributor to fission gas swelling, and creep-related damage of the skeleton appears to be the dominant mechanism for fission gas release and bubble connection. This study can provide technical support for the multi-scale thermo-mechanical behavior analysis of many advanced fuel elements.

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基于连续力学的UO2燃料裂变气体膨胀与释放耦合行为多尺度模拟

在极端堆内环境下，气态裂变产物在核燃料内不断积累，造成宏观燃料膨胀和裂变气体释放。裂变气体膨胀和释放效应相互耦合，与裂变气体原子在燃料颗粒内的扩散行为有关。随着气泡的演化，燃料转变为多孔结构，使其宏观热力学性能下降，从而影响燃料元件的整体热力学行为。对裂变气体膨胀与释放的耦合行为进行多尺度模拟研究，并实现对这些行为的准确预测，是反应堆工程设计中必不可少的科学问题和重要关注。本研究认为多孔燃料的宏观体积变化和裂变气体释放行为与裂变气体原子的扩散、颗粒间气泡的生长、晶粒再结晶效应和固体骨架的蠕变变形有关。基于连续介质力学理论，考虑气泡内压力、表面张力和外部静水压力的作用，建立了描述裂变气体膨胀与释放耦合行为的多尺度模型。大量的实验结果验证了该模型的正确性。此外，还揭示了裂变气体膨胀和释放耦合行为的潜在机制。研究发现，周围骨架的蠕变变形是裂变气体膨胀的主要原因，骨架的蠕变损伤是裂变气体释放和气泡连接的主要机制。该研究可为多种先进燃料元件的多尺度热-力学行为分析提供技术支持。

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.