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Analysis of steam generator tube rupture accidents for the development of mitigation strategies

  • Bang, Jungjin (School of Energy Systems Engineering, Chung-Ang University) ;
  • Choi, Gi Hyeon (School of Energy Systems Engineering, Chung-Ang University) ;
  • Jerng, Dong-Wook (School of Energy Systems Engineering, Chung-Ang University) ;
  • Bae, Sung-Won (Korea Atomic Energy Research Institute) ;
  • Jang, Sunghyon (The University of Tokyo) ;
  • Ha, Sang Jun (Central Research Institute, Korea, Hydro & Nuclear Power Co.)
  • Received : 2021.03.29
  • Accepted : 2021.07.19
  • Published : 2022.01.25

Abstract

We analyzed mitigation strategies for steam generator tube rupture (SGTR) accidents using MARS code under both full-power and low-power and shutdown (LPSD) conditions. In general, there are two approaches to mitigating SGTR accidents: supplementing the reactor coolant inventory using safety injection systems and depressurizing the reactor coolant system (RCS) by cooling it down using the intact steam generator. These mitigation strategies were compared from the viewpoint of break flow from the ruptured steam generator tube, the core integrity, and the possibility of the main steam safety valves opening, which is associated with the potential release of radiation. The "cooldown strategy" is recommended for break flow control, whereas the "RCS make-up strategy" is better for RCS inventory control. Under full power, neither mitigation strategy made a significant difference except for on the break flow while, in LPSD modes, the RCS cooldown strategy resulted in lower break and discharge flows, and thus less radiation release. As a result, using the cooldown strategy for an SGTR under LPSD conditions is recommended. These results can be used as a fundamental guide for mitigation strategies for SGTR accidents according to the operational mode.

Keywords

Acknowledgement

This research was partly supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP: Ministry of Science, ICT and Future Planning) (No. NRF-2017M2B2B1072552) and by the Nuclear Safety Research Program through the Korea Foundation Of Nuclear Safety (KoFONS) funded by the financial resource granted by the Nuclear Safety and Security Commission (NSSC) of the Republic of Korea (No. 1305008).

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