XAPR中破口失水事故下堆芯自然循环冷却能力的功能可靠性研究

Functional Reliability Investigation on Capacity of Reactor Core Natural Circulation Cooling in XAPR under MLOCA

功能失效是导致自然循环系统运行失效的重要因素,需在其可靠性分析中予以考虑。针对多维不确定性参数及小功能失效概率问题,提出了一种将改进响应面法及重要抽样子集模拟法相结合的功能可靠性分析方法。以西安脉冲堆(XAPR)堆池水自然循环冷却为例,结合中破口失水事故,考虑输入参数及模型的不确定性,对其进行了功能可靠性评估和灵敏度分析。结果表明:XAPR堆芯自然循环功能失效概率为3.796×10^(-3),需充分考虑系统功能的可靠性。本文方法具有较高的计算效率,同时又能保证很高的计算精度,对XAPR堆芯自然循环非线性功能函数具有很强的适应性。

Functional failure becomes an important factor in the natural circulation system operation failure,which needs to be considered in the system reliability analysis.In order to solve the problem of multi-dimensional uncertainty parameters and small functional failure probability of passive system,an efficient functional reliability estimation method based on improved response surface and importance sampling subset simulation methods was presented.This method was applied in natural circulation cooling in Xi’an Pulsed Reactor (XAPR) core.Combined with MLOCA,the uncertainties related to the input parameters and the model were considered.And then the probability of functional failure and the sensitivity measures were estimated.The assessment results show that the functional failure probability of natural circulation for XAPR core is 3.796×10^-3,and the functional failure in the passive system reliability analysis should be fully considered.This method has high computed efficiency and excellent computed accuracy compared with traditional probability analysis methods,and it is robust to nonlinear functional function of natural circulation for XAPR core.