非能动核电厂全厂断电事故自然循环现象研究  

Study on natural circulation phenomena of passive nuclear power plant under station blackout accident

作　　者：刘宇生[1] 许超 攸国顺[1] 安婕铷 庄少欣[1] LIU Yusheng;XU Chao;YOU Guoshun;AN Jieru;ZHUANG Shaoxin(Nuclear and Radiation Safety Center,Ministry of Environmental Protection,Beijing 100082,China)

机构地区：[1]环境保护部核与辐射安全中心,北京100082

出　　处：《核技术》2018年第11期73-79,共7页Nuclear Techniques

基　　金：国家科技重大专项(No.2015ZX06002007)资助~~

摘　　要：为识别全厂断电事故下非能动核电厂的主要热工水力现象,对AP1000核电厂全厂断电工况下的事故序列和自然循环现象进行了研究。通过建立AP1000的节点模型,进行了全厂断电事故序列的模拟,并划分了事故阶段,分析了非能动堆芯冷却系统中堆芯补水箱(Core Makeup Tank, CMT)投入失效和安全壳内置换料水箱(In-containment refueling water storage tank, IRWST)参数异常对事故自然循环过程的影响,研究结果表明:全厂断电事故下,非能动核电厂的堆芯衰变热由多个单相自然循环过程导出,其中堆芯与非能动余热排出热交换器(Passive Residual Heat Removal Heat Exchanger, PRHR HX)之间的自然循环对堆芯衰变热的导出具有显著影响。根据热阱的不同和系统参数变化的特点,事故序列可划分为主回路自然循环、非能动堆芯冷却系统(Passive Core Cooling System, PXS)自然循环和长期冷却三个阶段;CMT投入、IRWST水箱参数对PXS自然循环过程存在重要影响。[Background] Station blackout （SBO） accidents increasingly become the focus of research in the field of nuclear safety after Japan＇s Fukushima nuclear plant accident. Core decay heat under SBO condition will be transferred by natural circulation （NC） occurring in passive systems for the nuclear plants incorporated passive safety design concept such as AP 1000 or CAP1400. As a result, response of safety systems will differ in accident sequence and kind between passive safety plant and traditional plant. [Purpose] This study aims to identify main thermal hydraulic phenomena of passive nuclear power plants （NPPs） during SBO accident. [Methods] SBO accident progress and NC phenomena of AP1000 were investigated. The event sequence and stages were obtained as a result of Relap5 simulation with the nodalization model established according to design parameters. The sensitivity analysis for injection quantity of core makeup tank （CMT） and parameter deviation of in-containment refueling water storage tank （IRWST） were also conducted in the calculation. [Results] The results show that multiple NC phenomena occur in loop formed by core, steam generators, passive residual heat removal heat exchanger （PRHR HX）, and CMTs under accident conditions. The whole SBO accident progress of passive NPPs can be divided into three periods, namely reactor coolant system （RCS） NC process, passive core cooling system NC process and long term cooling process, based on characteristics of heat sink and parametric variation. What is more, the natural circulation rate between core and PRHR HX, pressure of RCS are both significantly affected by the injection failure of one CMT and parameter deviation of IRWST. [Conelusions] The NC process between core and PRHR HX plays a vital role in removal of core decay heat. The multiple NC processes occurring in passive core cooling system NC process period are unique to passive NPPs and they are worthy of research in experimental verification and code development.

关 键 词：全厂断电 自然循环 非能动核电厂 AP1000 

分 类 号：TL364.4[核科学技术—核技术及应用]