大亚湾核电站改进燃料管理中的超温和超功率ΔT紧急停堆整定值初步研究

Preliminary Overtemperature ΔT and Overpower ΔT Setpoint Analysis in Improved Fuel Management for Daya Bay NPP

加深燃耗和延长换料周期是提高核电站经济效益的手段之一。但燃耗加深后，偏离泡核沸腾比ＤＮＢＲ限制值将增大；长燃耗的堆芯装载布置使径向功率峰因子Ｆｘｙ上升、额定工况和事故工况下的最小ＤＮＢＲ大幅度下降。在大亚湾核电站改进燃料管理初步可行性研究中分析那些ＤＮＢＲ裕量较小的事故时，如沿用《广东核电站最终安全分析报告》ＦＳＡＲ中给出的超温和超功率保护定值进行计算，其计算结果不能满足ＤＮＢＲ安全限制准则。分析其原因，是由于ＤＮＢＲ准则值和Ｆｘｙ的改变，超温和超功率保护图也将随之变化，使原整定值不能满足安全要求。因此，需重新确定超温和超功率ΔＴ保护整定值。采用ＦＬＩＣＡⅢ程序和ＤＥＬＴＡＴ程序，对长燃耗条件下的超温和超功率ΔＴ整定值进行了初步研究，并将其结果应用于提棒事故分析，使该事故满足了ＤＮＢＲ安全准则。

One of the way to enhance the economic benefit for nuclear power plant is to deepen burnup and extend reload cycle.If the burnup is deepened,the departure from nucleate boiling ratio DNBR limit will increase.The core loading pattern makes the radial power peak factor Fxy increase,the minimum DNBR under nominal condition and accident condition will decrease.If the overtemperature ΔT and overpower ΔT setpoints given in GNPS FSAR are used to analyze the accidents for GNPS improved fuel management study,which have lower DNBR margin,the results will not meet the DNBR safety criterion.In fact,the overtemperature ΔT and overpower ΔT setpoints will change along with the changes of DNBR safety criterion and Fxy,it is reasonable that formerly setpoints can not meet the safety requirement.So it is necessary to re determine the overtemperature ΔT and overpower ΔT setpoints.FLICA _F code and DELAT code are used to determine the overtemperature ΔT and overpower ΔT setpoints for long cycle.The results are used in control rod withdraw accident analysis,and the DNBR safety criterion are met.