考虑一二回路耦合的核电站凝结水泵跳闸工况分析

Analysis of Condensate Pumptrip in Nuclear Power Plant Considering Two-Circuit Coupling

摘要: 凝结水系统是核电站二回路的主要组成部分之一，丧失凝结水会导致除氧器水位降低，进而导致给水泵跳闸，影响SG水位。核电站目前对于凝结水泵跳闸的控制策略是快速降负荷以减少核岛对主给水量的需求，稳定除氧器和SG水位。本文以先进压水堆AP1000为例，通过FLOWNEX和RELAP软件将一二回路进行耦合计算，对凝结水泵跳闸后未降负荷工况进行分析计算。计算结果表明，凝结水泵跳泵后，除氧器水位会以0.009 m/s的速率下降，在运行148 s后，给水泵由于除氧器触发低低水位而跳闸，主给水完全丧失。在主给水完全丧失后38 s (运行186 s)，反应堆因SG水位低低而发生停堆。如果SG水位保护系统未响应，主给水流量与主蒸汽流量不匹配，有在主给水完全丧失之前因SG水位低低而停堆的风险。

Abstract: The condensate system is one of the main components of the second circuit of the nuclear power plant. The loss of condensate water will cause the deaerator water level to decrease, which will cause the feed pump to trip and affect the SG water level. The current control strategy for condensate pump tripping at the nuclear power plant is to rapidly reduce the load to reduce the main water supply demand of the nuclear island and stabilize the deaerator and SG water level. Taking advanced pressurized water reactor AP1000 as an example, this paper analyzes and calculates the tripping condition of condensate pump by coupling the one-two circuit with FLOWNEX and RELAP software. The calculation results show that after the condensate pump jumps off the pump, the water level of the deaerator will drop at a rate of 0.009 m/s. After 148 s of operation, the feed pump will trip due to the low water level triggered by the deaerator, and the main water supply will be completely lost. At 186s after operation (38 s after total loss of main feed water), the reactor was shut down due to low SG water level. If the SG water level protection system is not responsive, there is a risk of shutdown due to low SG water level before the main feed is completely lost.