Emergency condition analysis for MBLOCA along with SBO initiated severe accident using MELCOR. Issue 2 (February 2019)

• Record Type: Journal Article
• Authors: Wang, Ning; Chen, Lei; Wang, Renze; Yang, Yapeng; Xu, Xiaoxiao; Feng, Zongyang; Jia, Linsheng
• Is Part Of: IOP conference series. Volume 227:Issue 2(2019)
• Publication Date: 2019-02
• Subjects: Earth sciences -- Periodicals; Environmental sciences -- Congresses; Environmental sciences -- Periodicals; 550.5
• DOI: 10.1088/1755-1315/227/2/022011
• Languages: English
• ISSNs: 1755-1307

Abstract

Abstract: Much interest in severe accident research has been attracted since Fukushima accident, which indicates that severe accident could possibly happen although the probability is extremely low. Although many researches have been conducted in severe accident progression simulation and emergency condition analysis, it is still necessary to do some research on emergency conditions of severe accident that have not been sufficiently analysed. In this paper, a 250mm medium break loss of coolant accident (MBLOCA) in cold leg along with station blackout (SBO) initiated severe accident was simulated using MELCOR code. Before the calculation, steady state was simulated in order to check the model. Main parameters of the model were compared with operating parameters of nuclear power plant (NPP), and relative error was acceptable, which indicated that the model could be used to simulate the accident. Emergency condition progression of the accident was obtained, including start of core uncover, start of zirconium-water reaction, failure of fuel cladding and failure of the lower head. Thermal-hydraulics response of reactor was analysed. The calculation ended with failure of lower head, and the response of the containment was not studied. Results show that a 250mm break is relative a large one among MBLOCA, and the progression is similar with that of large break loss of coolant accident (LBLOCA). The accident progresses quite fast. The core starts to melt at 526s, and lower head fails at 2314s. Results of the paper could be used to provide basis for decision making in case of emergency and severe accident mitigation.