功能可靠性分析方法在XAPR堆芯自然循环可靠性评价中的应用

功能失效是导致自然循环系统运行失效的重要因素，需要在其可靠性分析中予以考虑。基于功能可靠性评价流程，通过RELAP5程序模拟自然循环物理过程，对西安脉冲堆（XAPR）池水自然循环冷却堆芯能力的可靠性进行评价。结合中破口失水事故，根据包壳完整性的功能准则，确定影响自然循环的关键参数；采用拉丁超立方抽样确定输入参数组合，进行参数敏感性分析和功能可靠性评价，并将功能可靠性评价结果整合到概率安全评价（PSA）模型中。分析结果表明:在PSA模型中不仅需要考虑硬件可靠性，还应充分考虑功能可靠性，以更好地指导XAPR运行及提高其安全性。 

Application of Functional Reliability Assessment Method in Reliability Analysis of XAPR Reactor Core Natural Circulation

Functional failure becomes an important factors in natural circulation system operation failure, which needs to be considered in the system reliability analysis. However, the reliability evaluation work of these passive systems is still in the primary stage. In this paper, based on the passive functional reliability evaluation process, the physical process of passive natural circulation was simulated by RELAP5 program and the reliability on capacity of natural circulation cooling in Xi'an Pulsed Reactor (XAPR)reactor core was estimated. Combined with middle loss of coolant accident, the functional failure criteria was established based on the integrity of fuel claddings and the key parameters of natural circulation were identified. According to Latin Hypercube Sampling, sensitivity assessment and functional reliability evaluation were carried out. Then the functional reliability evaluation results can be integrated in the Probabilistic safety accessment (PSA)?model. The results show that XAPR PSA not only analyzed the hardware reliability but also considered the functional reliability, to better guide the XAPR operation and improve the safety.