In this study, a multi-physics modeling method was developed to analyze a nuclear fuel rod's thermo-mechanical behavior especially for high temperature anisotropic creep deformation during ballooning and burst occurring in Loss of Coolant Accident (LOCA). Based on transient heat transfer and nonlinear mechanical analysis, the present work newly incorporated the nuclear fuel rod's special characteristics which include gap heat transfer, temperature and burnup dependent material properties, and especially for high temperature creep with material anisotropy. The proposed method was tested through various benchmark analyses and showed good agreements with analytical solutions. From the validation study with a cladding burst experiment which postulates the LOCA scenario, it was shown that the present development could predict the ballooning and burst behaviors accurately and showed the capability to predict anisotropic creep behavior during the LOCA. Moreover, in order to verify the anisotropic creep methodology proposed in this study, the comparison between modeling and experiment was made with isotropic material assumption. It was found that the present methodology with anisotropic creep could predict ballooning and burst more accurately and showed more realistic behavior of the cladding.

在这项研究中，开发了一种多物理场建模方法来分析核燃料棒的热机械行为，特别是在冷却剂损失事故 (LOCA) 中发生膨胀和爆裂期间的高温各向异性蠕变变形。在瞬态传热和非线性力学分析的基础上，本工作新结合了核燃料棒的特殊特性，包括间隙传热、温度和燃耗相关的材料特性，特别是具有材料各向异性的高温蠕变。所提出的方法通过各种基准分析进行了测试，并显示出与分析解决方案的良好一致性。从包层爆裂实验的验证研究中，假设了 LOCA 场景，结果表明，目前的发展可以准确预测膨胀和爆裂行为，并显示出预测 LOCA 期间各向异性蠕变行为的能力。此外，为了验证本研究中提出的各向异性蠕变方法，在各向同性材料假设下进行了建模与实验的比较。发现采用各向异性蠕变的本方法可以更准确地预测膨胀和爆裂，并显示出更真实的包层行为。