In LWR fuel claddings the embrittlement due to hydrogen precipitates (i.e., hydrides) is a degrading mechanism that concerns in nuclear safety, particularly in dry storage. A relevant factor is the radial distribution of the hydrogen absorbed, especially the hydride rim formed. Thus, a reliable assessment of fuel performance should account for hydrogen migration. Based on the current state of modelling of hydrogen dynamics in the cladding, a 1D radial model has been derived and coupled with the FRAPCON code.

The model includes the effect of the oxidation front progression on in-clad hydrogen migration, based on experimental observations found (i.e., dissolution/diffusion/re-precipitation of the hydrogen in the matrix ahead of the oxidation front). A remarkable quantitative impact of this new contribution has been shown by analyzing the hydrogen profile across the cladding of several high burnup fuel scenarios (>60 GW d/tU); other potential contributions like thermodiffusion and diffusion in the hydride phase hardly make any difference. Comparisons against PIE measurements allow concluding that the model accuracy notably increases when the effect of the oxidation front is accounted for in the hydride rim formation. In spite of the promising results, further validation would be needed.

在轻水堆燃料包壳中，由于氢沉淀物（即氢化物）引起的脆化是涉及核安全特别是在干燥存储中的降解机制。一个相关因素是吸收的氢，特别是形成的氢化物边沿的径向分布。因此，对燃料性能的可靠评估应考虑到氢的迁移。基于包层中氢动力学建模的当前状态，已导出一维径向模型并将其与FRAPCON代码耦合。

基于发现的实验观察结果（即，氢在氧化前沿之前在基质中的溶解/扩散/再沉淀），该模型包括氧化前沿进展对包层氢迁移的影响。通过分析几种高燃耗燃料情景（> 60 GW d / tU）的整个包壳中的氢分布，已表明了这一新贡献的显着定量影响。氢化物相中的热扩散和扩散等其他潜在贡献几乎没有任何区别。与PIE测量值的比较可以得出结论，当在氢化物边沿形成过程中考虑到氧化前沿的影响时，模型的准确性会显着提高。尽管结果令人鼓舞，但仍需要进一步验证。