先进三代核电AP1000丧失正常给水事故研究

Study on Loss of Normal Feedwater Accident of Advanced Third Generation NPP AP1000

本文对先进三代核电AP1000的丧失正常给水事故从稳压器满溢、冷却剂系统压力边界完整性和燃料包壳完整性方面进行分析研究。由于AP1000设计中考虑汽机停机可能会引起电网扰动,因此考虑了反应堆紧急停堆之后汽机停机引起的丧失厂外交流电的情况。丧失厂外交流电后,主泵将停运,一次侧排热能力将降低,冷却剂升温升压;但丧失厂外交流电也将引起化容系统不可用,从而可能降低稳压器满水和冷却剂系统超压的风险。因此,本文对于不同的限制准则,分别进行交流电是否有效的分析评价。结果表明,无论交流电是否有效,在非能动堆芯冷却系统的运行下和操纵员动作下,堆芯余热可以有效导出,稳压器没有满溢,冷却剂系统的压力边界以及燃料包壳的完整性均能得到保证。

This paper studies the loss of normalfeedwater accident of advanced third generation NPP AP1000 from the aspects of overfilling of pressurizer and integrity of RCS's pressure boundary and fuel cladding.For each criterion,different initial conditions and assumptions of reactor control and protection system will be considered to get the most conservative results. Furthermore,the turbine trip may lead to disruption of the grid in the design of AP1000,thus a loss of offsite AC power will be considered due to turbine trip following reactor trip. The reactor coolant pump will coast down after the loss of offsite AC power,the capability of heat removal of primary side will decrease and the RCS's temperature and pressure will increase. However the loss of offsite AC power will also cause the isolation of Chemical and Volume Control System,which may reduce the risk of overfilling of pressurizer and overpressure of RCS.Therefore,for different limiting criterion,it is necessary to analyze availability of AC power. The results show that with the operation of PXS and the action of the operator,core residual heat could be removed effectively,pressurizer will not overfill and integrity of RCS's pressure boundary and fuel cladding will be maintained whether AC power is available or not.