堆芯旁通流量对小破口失水事故影响分析

Analysis on the Influence of Core Bypass Flow during SBLOCA

核电厂在小破口失水事故（SBLOCA）期间的行为受到许多参数影响，堆芯旁通流量就是其中之一。本文基于秦山核电厂的数据，用Relap5／Mod3程序模拟了不同堆芯旁通流量值的几个工况。计算结果表明堆芯旁通流量越小，环路水封扫除前堆芯水位下降得越低。燃料包壳峰值温度越高，环路水封扫除的时间越早。本文对计算结果作了分析，并根据简单的数学模型，从原理上对一些基本现象给出了解释。

Many parameters affect the behavior of NPP during a Small Break Loss of Coolant Accident （SBLOCA）. The bypass flow between the upper plenum and the downcomer is one of them. Based on the Qinshan NPP database, the cases with different core bypass flow are analyzed using RelapS/Med3. The calculation results show that the smaller the core bypass flow is, the lower the core collapsed level depression before loop seal clearance is, the higher the fuel clad peak temperature is, and the earlier the loop seal clearance is. Some fundamental phenomena are explained in principle with simplified mathematical models.