Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
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Application of a combined safety approach for the evaluation of safety margin during a Loss of Condenser Vacuum event

  • Shin, Dong-Hun (Department of Quantum and Nuclear Engineering, Sejong University) ;
  • Jeong, Hae-Yong (Department of Quantum and Nuclear Engineering, Sejong University) ;
  • Park, Moon-Ghu (Department of Quantum and Nuclear Engineering, Sejong University) ;
  • Sohn, Jung-Uk (ZettaCognition)
  • Received : 2021.09.08
  • Accepted : 2021.11.06
  • Published : 2022.05.25
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Abstract

A combined safety approach, which uses a best-estimate computer code and adopts conservative assumptions for safety systems availability, is developed and applied to the safety margin evaluation for the Loss of Condenser Vacuum (LOCV) of the 1000 MWe Korean Nuclear Power Plant. The Multi-dimensional Analysis of Reactor Safety-KINS standard (MARS-KS) code is selected as a best-estimate code and the PAPIRUS program is used to obtain different initial operational conditions through random sampling of control variables. During an LOCV event, fuel integrity is not threatened by the increase in Departure from Nuclear Boiling Ratio (DNBR). However, the high pressure in the primary coolant system and the secondary system might affect the system integrity. Thus, the peak pressure becomes a major safety concern. Transient analyses are performed for 124 cases of different initial conditions and the most conservative case, which results in the highest system pressure is selected. It is found the suggested methodology gives similar peak pressures when compared to those predicted from existing methodologies. The proposed approach is expected to minimize the time and efforts required to identify the conservative plant conditions in the existing conservative safety methodologies.

Keywords

Acknowledgement

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2016R1A5A1013919) and by the Korea Foundation of Nuclear Safety (KoFONS) grant funded by the Nuclear Safety and Security Commission (NSSC) of Republic of Korea (No.2101062).

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