同一燃耗区域核燃料包壳破损建模分析

核反应堆燃料包壳是构成反应堆安全的重要屏障, 一旦发生破损,放射性裂变产物就会释放到一回路的冷却剂中。本文通过一回路134Cs/137Cs比值确定破损燃料棒所在燃耗区域，对该燃耗区域裂变产物的产生、裂变产物进入芯块间隙、一回路核素平衡分别进行建模，然后，利用建立的数学模型对破口处裂变产物向一回路释放过程进行分析，得出破口的大小和破损根数及所在燃耗区域，并以压水堆核电站燃料包壳破损的数据进行验证，证实了模型的合理性。

Modeling and analysis situation of fuel rod cladding crevasse in same burnup area

The fuel cladding is the first barrier of nuclear power plant. Once it failed, fission products would release to reactor coolant system (RCS) through the crevasse. So determining the general position and size of the crevasse would help a lot to know the seriousness of the accident. This paper builds four models, which are models for cases of fission products accumulated in fuel pellets, diffused to the gap between pellet and cladding and released from the gap to RCS, and the balance model in RCS. By detecting the activities of fission products in RCS, we can deduce the initial products released from the crevasse and subsequently the specific situation of the crevasse. These models have been proved applicable by an accident of fuel rod failure in the Daya Bay Nuclear Power Plant.