CPY核电厂低温超压保护改进的研究

Study of on Site LTOP Update for CPY Nuclear Power Plant

法国CPY核电厂的双重低温超压保护,即在一回路满水的冷停堆工况下,降低稳压器先导式安全阀的开启/关闭压力整定值,在余热排出系统(RRA)正常运行时由RRA安全阀提供低温超压保护,在RRA因破口或误操作隔离时,则由降低了开启/关闭压力整定值的稳压器安全阀提供低温超压保护。低温超压的瞬态模拟和应力分析的结果显示降低稳压器安全阀的开启/关闭压力整定值能够在低温冷停堆状态下为反应堆冷却剂系统(RCP)提供有效的超压保护,避免反应堆压力容器出现脆性断裂,确保一回路压力边界的结构完整性。

The dual Low Temperature Overpressure Protection(LTOP)of French CPY nuclear power plant when the RCP is at solid cold shutdown state is implemented by decreasing the opening/closing pressure set points of the pressurizer safety valve;then the LTOP is implemented by the RRA safety valve when the RRA operation is normal;in case of isolation of RRA because of break or mishandling,the LTOP is implemented by the pressurizer safety valve with decreased set points of opening/closing pressure.The results of transient simulations and stress analysis demonstrate that by decreasing the opening/closing pressure set points of the pressurizer safety valve,the LTOP is successfully implemented,the brittle fracture of RPV is avoided and hence the structural integrity of pressure boundary of RCP is guaranteed.