CAP1400 MSLB事故破口谱分析及极限工况瞬态分析

Break Spectrum Analysis and Transient Analyses of Limited Condition for CAP1400 MSLB

CAP1400核电厂与传统的"二代"核电厂区别较大。CAP1400反应堆在AP1000的基础上进行了一系列改进。采用RELAP5/MOD3.3程序建立CAP1400核电厂模型,对主蒸汽管道破裂事故的破口谱进行分析,结果表明,直到0.058m^2的蒸汽管道破口都不会触发反应堆停堆。对于0.059～0.105 m^2的蒸汽管道破口,反应堆由超功率△T信号触发停堆。对于0.106～0.15 m^2的蒸汽管道破口,反应堆由蒸汽管道低压力安注信号触发停堆。从DNB和燃料中心熔化保护角度考虑,极限工况是破口尺寸为超功率触发停堆的最大破口尺寸0.105 m^2。对极限工况的热工水力瞬态进行研究,分析堆芯流量、热流密度、温度、压力等关键参数随时间变化的趋势。采用VIPRE程序对DNBR进行计算,得到事故对应的最小DNBR为1.914,大于验收准则1. 45,表明CAP1400反应堆在主蒸汽管道破裂事故下安全可靠。

CAP1400 reactor is quite different from traditional Gen.II nuclear power plants worldwide.The primary system of CAP1400 is modeled using RELAP5/MOD 3.3 code, and the transient thermal hydraulic characteristics are analyzed under the accident sequence of main steam line break (MSLB).DNBR of core is calculated by VIPRE code.Through summarizing the break spectrum, the results show that when the break size is less than 0.058 m^2 , the reactor will not shut down;when the break size is between 0.059 m^2 and 0.105 m^2 , the reactor will shut down by overpower Δ T triggering reactor trip;and when the break size is between 0.106 m 2 and 0.15 m^2 , the reactor will shut down by the steam pipe low pressure injection signal.And the limited condition is 0.105 m^2 .The results of the limited condition show that the core heat flux and reactor coolant system temperature and pressure fluctuate with time.The minimum value of the DNBR is 1.914, greater than limited value 1.45.It indicates that CAP1400 reactor is very safe and reliable under the MSLB condition.