AP1000首堆非能动堆芯补水箱(CMT)再循环试验流量分析方法研究

The Study on the Flowrate Analysis Method for the Passive Core Makeup Tank(CMT)Recirculation Test in the First AP1000 Nuclear Power Plant

堆芯补水箱(CMT)再循环试验是AP1000的首三堆试验,目的是验证CMT再循环流量满足应急补水和硼化的安全功能要求,通过测量试验流量来证明满足安全分析要求(验收准则),因此试验成功的关键是获得较高精度的流量。由于CMT出入口管道均没有设置永久流量计,若使用临时超声波流量计(UFM)会带来较大的流量不确定性。本文通过采用ASME流量计测量和误差分析法规中介绍的方法,利用CMT容积和液位的关系(MAP法)在机组冷态条件下标定UFM和压差法(DP法),得到流量修正因子。因为相互独立的流量分析方法可以采用权重因子方法计算综合的流量偏差,可减小过于保守的流量误差。以上分析计算可以得到与真实流量较为接近的计算流量(置信度95%),并通过与热工软件RELAP 5和NOTRUMP模型预测流量对比,数据曲线的符合性较为一致,证明试验满足验收准则且该分析方法的合理性。

The core makeup tank(CMT)recirculation test is one of the F3OAK tests of AP1000.The purpose of test is to validate the safety function requirement of the emergency makeup water and boronation.The measured flowrate with a high accuracy is the key of the successful test,because the requirement for the safety analysis(test acceptance criteria)is verified by measuring test flowrate.Because the inlet and outlet line of CMT have no permanent flow-meter,there will have a large uncertainty of flowrate if use temporary ultrasonic flowmeter(UFM).The flowrate analysis method in this paper come from the ASME code for the flowrate measurement and test uncertainty.The method of volume&level(MAP)relationship is used to calibrate the flowrate derived by UFM and differential gauge(DP)method in the cold and atmosphere condition to get the corrected factors.The flow uncertainty from independent analysis method can be adjusted to a combined one,which decreases the over-conservative flow uncertainty.The final calculated flowrate will get close to real one,with 95%level of confidence,and its rationality is proved through comparing with the result of RELAP 5 and NOTRUMP.The fitness of curves is well,so it proves the acceptance criteria is satisfied and rationality of the analysis method.