Effect of passive auxiliary feedwater system on mitigation of DEC accidents: Part I. MSGTR, SBLOCA-LOSI, and SBO

• Published in: Annals of nuclear energy 2024-10, Vol.206, p.110643, Article 110643
• Main Authors: Park, Youngjae, Jeon, Seong-Su, Lee, Dong-Young, Wook Chung, Young, Gyun Nam, Sang, Hyun Hwang, Do
• Format: Article
• Language: English
• Subjects: Design extension condition (DEC); Multiple steam generator tube ruptures (MSGTR); Passive auxiliary feedwater system (PAFS); RELAP5; Small break loss of coolant accident with loss of safety injection (SBLOCA-LOSI); Station blackout (SBO)
• ISSN: 0306-4549; 1873-2100
• DOI: 10.1016/j.anucene.2024.110643

•RCS cooling by SG is essential for mitigation of MSGTR, SBLOCA-LOSI, and SBO.•PAFS was developed as an advanced safety design feature to replace the active AFWS.•The MSGTR, SBLOCA-LOSI, and SBO in 1,000 MWe PWR with PAFS are analyzed by RELAP5.•The effects of PAFS for accident mitigation and operator actions are investigated. Multiple Steam Generator Tube Ruptures (MSGTR), Small Break Loss of Coolant Accident with Loss of Safety Injection (SBLOCA-LOSI), and Station Blackout (SBO) are Design Extension Condition (DEC) accidents where the SG secondary-side cooling with operator actions are essential for the mitigation of the accidents. In the Republic of Korea, the Passive Auxiliary Feedwater System (PAFS) was developed to replace the active Auxiliary Feedwater System (AFWS). It is important to examine the existing accident mitigation strategies and evaluate whether they can be effectively applied to DECs using PAFS as well. To investigate the changes in accident mitigation characteristics and operator actions when PAFS is implemented instead of AFWS, the DEC accidents such as MSGTR, SBLOCA-LOSI, and SBO are analyzed with RELAP5/MOD3.3. Research results presented in this paper have significant implications and can be utilized to improve the accident mitigation strategies and the operator training for DEC accidents where PAFS is implemented.