Nuclear Techniques ›› 2018, Vol. 41 ›› Issue (11): 110603-110603.doi: 10.11889/j.0253-3219.2018.hjs.41.110603

• NUCLEAR ENERGY SCIENCE AND ENGINEERING • Previous Articles     Next Articles

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

LIU Yusheng, XU Chao, YOU Guoshun, AN Jieru, ZHUANG Shaoxin   

  1. Nuclear and Radiation Safety Center, Ministry of Environmental Protection, Beijing 100082, China
  • Received:2017-07-24 Revised:2018-04-19 Online:2018-11-10 Published:2018-11-20
  • Supported by:
    Supported by Major National Science and Technology Program (No.2015ZX06002007)

Abstract: [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 AP1000 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.[Conclusions] 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.

Key words: Station blackout, Natural circulation, Passive nuclear power plant, AP1000

CLC Number: 

  • TL364+.4