方家山核电汽水分离再热器壳侧疏水设计优化与改进

Design Optimization and Improvement of the Drainage on the Shell Side of the Moisture Separator and the Reheater in Fangjiashan Nuclear Power Plant

方家山核电为两台百万千瓦级压水堆核电机组,采用二代改进型压水堆技术。两台汽水分离再热器的壳侧疏水泵长期在高温条件下连续运行,故障率较高。原设计仅考虑每列MSR的壳侧疏水设置1台疏水泵,故当疏水泵故障停运时,MSR壳侧疏水必须切换排至凝汽器,会造成机组热效率下降,如同时备用疏水阀门故障会危及机组安全。通过对汽水分离再热器壳侧疏水设计优化的必要性与改进的可行性进行分析,采取在每列MSR的壳侧疏水管增设一台疏水泵回路构成备用列的方式,实现当一台疏水泵故障停运后另一台疏水泵启动,将疏水排至ABP系统上游管道。避免了因一台疏水泵故障停运导致MSR的壳侧疏水只能依靠单一管线切换至凝汽器。改进结果达到了预期,增加了MSR疏水泵运行方式的灵活性,提高了GSS系统壳体疏水的可靠性。

Fangjiashan nuclear power plant consists of two 1000 MWe pressurized water reactor nuclear power plants,using the second-generation plus pressurized water reactor technology.The shell-side drain pumps of the two MSRs have been running continuously under high temperature conditions for a long time,so the failure rate is high.The original design only considers that one drain pump is installed on the shell side drain of each MSR train,so when the drain pump fails and shuts down,the MSR shell side drain must be switched to drain to the condenser,which will cause the thermal efficiency of the plant to decrease,such as the failure of the standby drain valve at the same time.It will endanger the safety of the plant.This paper analyzes the necessity of the design optimization and feasibility of the design improvement for the drainage on the shell side of the MSR.A drain pump circuit is added to the shell side drain pipe of each MSR train to form a standby train,so that when one drain pump fails and shuts down,the other drain pumps will start and drain to the upstream pipelines of the ABP system.It is avoided that once a drain pump fails,the shell side drainage of the MSR can only be switched to the condenser by a single pipeline.The optimization and improvement achieve the expectation that both the flexibility of the operation mode of the MSR drainage pump and t he reliability of the shell drainage of the GSS system have been improved.