In this article it is examined how the non-uniform oxidation and the resulting change in the properties of the ballooned cladding in a LOCA scenario relate to the assumption of a “uniform ballooning” used in the LOCA criteria. This was achieved by creating a code that calculates how steam diffuses through the opening in the cladding after the burst, what happens during oxidation if the cladding wall thickness is non-uniform, and how this affects the load-bearing capacity of the fuel rod. The results were compared to experimental data and results of calculations using uniform geometry.

With this program the severity of oxidation for different geometries and scenarios was calculated. The results show that local values differ significantly for uniform and non-uniform oxidation. We have also examined the variation in the load bearing capacity in different scenarios and we have found that for a design basis LOCA accident the remaining thickness of the beta layer in the zirconium cladding will prevent brittle failure.

在本文中，我们将研究LOCA场景中非均匀氧化和膨胀包层特性的最终变化如何与LOCA标准中使用的“均匀膨胀”假设有关。这是通过创建一个代码来实现的，该代码计算爆裂之后蒸汽如何通过包层中的开口扩散，如果包层壁厚不均匀，在氧化过程中会发生什么，以及这如何影响燃料棒的承载能力。将结果与实验数据和使用均匀几何形状的计算结果进行比较。

通过该程序，可以计算出不同几何形状和场景下的氧化严重程度。结果表明，对于均匀氧化和非均匀氧化，局部值显着不同。我们还研究了在不同情况下承载能力的变化，并且发现基于LOCA事故的设计，锆包层中β层的剩余厚度将防止脆性破坏。