压水堆破口事故下裂变产物源项释放及衰变热分析  

Analysis of fission product source term release and decay heat under pressurized water reactor rupture accident

作　　者：袁显宝[1,2] 彭珏钦 张彬航 毛璋亮 唐海波 魏靖宇 周建军 YUAN Xianbao;PENG Jueqin;ZHANG Binhang;MAO Zhangliang;TANG Haibo;WEI Jingyu;ZHOU Jianjun(College of Science,China There Gorges University,Yichang 443002,China;College of Mechanical and Power Engineering,China There Gorges University,Yichang 443002,China;Hubei Key Laboratory of Hydroelectric Machinery Design&Maintenance,China There Gorges University,Yichang 443002,China)

机构地区：[1]三峡大学理学院,宜昌443002 [2]三峡大学机械与动力学院,宜昌443002 [3]三峡大学湖北省水电机械设备设计与维护重点实验室,宜昌443002

出　　处：《核技术》2024年第4期147-158,共12页Nuclear Techniques

基　　金：国家自然科学基金(No.12175116,No.12275153,No.11805112)资助。

摘　　要：反应堆严重事故时堆芯发生熔化现象,导致部分放射性源项不再留存于燃料中,将会通过各种途径释入环境,对周围造成严重的放射性污染。为了研究不同模型下裂变产物在压力容器内外释放量及其衰变热分布,分析喷淋系统对控制源项释放及热量的影响。基于典型的百万千瓦级压水堆核电站模型,利用一体化安全分析程序MAAP建模,分析计算CORSOR-M、CORSOR-O和ORNL-BOOTH三种源项释放模型反应堆一回路热管段破口叠加高、低压安注失效的事故序列和后果。结果表明:裂变产物源项主要在压力容器内释放,释放量远多于压力容器外的释放量。CORSOR-O模型下压力容器最晚融穿,安全壳失效最早;ORNL-BOOTH中压力容器虽最先融穿,但安全壳失效远晚于其他两种模型。源项释放差异导致不同模型衰变热现象不同,主要热源皆为挥发性裂变产物。开启喷淋不仅可以使悬浮碘化物充分控制在安全壳内,还能有效带走源项产生的衰变热,降低安全壳压力,保证安全壳完整性。[Background]During severe reactor accidents,melten core causes the radioactive source term material to be no longer retained in the fuel but is released into the environment,causing serious radioactive contamination in the surrounding areas.[Purpose]This study aims to investigate the release of fission products,both inside and outside the pressure vessel,using different models in order to analyze the effectiveness of the spray system in controlling the source term release and the decay heat generated.[Methods]Based on a typical mega kilowatt pressurized water reactor(PWR)nuclear power plant model,the integrated security analysis program MAAP was applied to modeling reactor rupture accident.Then,the accident sequence and consequences of the reactor primary circuit heat pipe breakage superimposed high and low voltage safety injection failure were calculated and analyzed under CORSOR-M,CORSOR-O and ORNL-BOOTH source term release models.[Results]The findings indicate that the fission product source term is mainly released in the pressure vessel,and the release amount is significantly higher than that released outside the pressure vessel.Under the CORSOR-O model,the pressure vessel fails the last whereas the containment fails the first;although the pressure vessel fails first in the ORNL-BOOTH model,the containment vessel fails much later than that in the other two models.The difference in source term release leads to different decay heat phenomena in different models,and the main heat source is the volatile fission product.Turning on the spray can not only keeps the suspended iodide in the containment vessel but also effectively removes the decay heat generated by the source items and reduces the pressure of containment.[Conclusions]The ORNL-BOOTH model results in lesser release of source term in the pressure vessel,the greatest variety of source term released,and the maximum time to containment failure.In addition,the opening of the spraying system effectively ensures the integrity of the containment.

关 键 词：破口事故 裂变产物源项 安全壳失效 喷淋系统 衰变热 

分 类 号：TL99[核科学技术—核技术及应用]