压水堆核电站乏燃料元件γ扫描测量

在压水堆核电站乏燃料元件检验中，完成了4根完整元件棒、4根破损元件棒的γ扫描测量，元件燃耗分布在9600～45000 MW?d/t（U）之间，获得了完整元件轴向相对燃耗分布、破损元件¹³⁷Cs分布及迁移流失情况。结果显示，破损元件均存在不同程度的Cs迁移流失，破口处存在¹³⁷Cs计数突变（降低）。破损元件¹³⁴Cs/¹³⁷Cs原子比分布与相邻完整元件基本一致，表明¹³⁴Cs、¹³⁷Cs流失比例近似相等，可用¹³⁴Cs/¹³⁷Cs原子比表征其相对燃耗分布；破口处可通过低挥发性核素¹⁵⁴Eu计数水平判断燃料芯块是否缺失。检验结果可为燃料元件破损原因分析及堆内行为分析提供重要依据。

Gamma Scanning of Spent Fuel Element from PWR

4 intact and 4 failed spent fuel elements from PWR with burnup range of 9600-45 000 MW?d/t（U） were measured by gamma scanning, and the axial Cs distributions were obtained, which can indicate the burnup distribution of the intact elements and the Cs loss of the failed elements. The results show that there are different degrees of Cs migration and loss in the failed elements, and there is a Cs counting mutation (decrease) at the failure position. The distribution of ¹³⁴Cs/¹³⁷Cs atom ratio of one failed element is basically the same with the sibling intact element, indicating that the loss ratio of¹³⁴Cs and ¹³⁷Cs is approximately equal, and the relative burnup distribution can be characterized by the atom ratio. The low volatility fission product ¹⁵⁴Eu can be used to identify the fuel pellet damage. The results can provide an important basis for the failure cause analysis and the in-pile behavior analysis.