VVER机组LBLOCA始发严重事故工况下堆芯出口温度BEPU分析

最佳估算加不确定性（BEPU）方法目前广泛应用于核电厂设计基准事故（DBA）的分析。考虑到严重事故现象复杂及不确定性较大，BEPU方法在严重事故领域应用较少。堆芯出口温度（CET）是核电厂安全运行的重要监测参数，本文以VVER1000压水堆核电厂为研究对象，采用BEPU方法对大破口失水事故（LBLOCA）始发严重事故工况下包壳破裂对应的CET进行不确定性分析，并对输入参数进行敏感性分析。计算结果表明：气隙释放对应CET的单侧统计容忍限值（95/95）为430.85 ℃；CET对输入参数中的衰变热系数和包壳厚度较为敏感。

BEPU Analysis of Core Exit Temperature under Severe Accident Initialed by LBLOCA for VVER Unit

Best estimate plus uncertainty (BEPU) method is widely used in design basis accident analysis in nuclear power plant nowadays. Considering complicated severe accident phenomenon and high uncertainty, the BEPU method is seldomly used in severe accident. Core exit temperature (CET) is an important monitoring parameter for safe operation of nuclear power plant (NPP). In this paper, VVER1000 pressurized water reactor nuclear power plant was taken as the research object, the BEPU method was used to study the uncertainty of CET corresponding to cladding rupture under severe accident initialed by large break loss of coolant accident (LBLOCA), and the sensitivity of the input parameters was analyzed. The results show that the unilateral tolerance limit (95/95) of CET corresponding to gas release is 430.85 ℃. The CET is more sensitive to the factor of decay power and the thickness of cladding.