중수로 증기발생기 다중 전열관 파단사고시 파단 전열관 수에 대한 영향 분석 = Influence Analysis on the Number of Ruptured SG u-tubes During mSGTR in CANDU-6 Plants

다국어 초록 (Multilingual Abstract)

An influence analysis on multiple steam generator tube rupture (mSGTR) followed by an unmitigated station blackout is performed to compare the plant responses according to the number of ruptured u-tubes under the assumption of a total of 10 ruptured u-tubes. In all calculation cases, the transient behaviour of major thermal-hydraulic parameters, such as the discharge flow rate through the ruptured u-tubes, reactor header pressure, and void fraction in the fuel channels is found to be overall similar to that of the base case having a single SG with 10 u-tubes ruptured. Additionally, as the conditions of low-flow coolant with high void fraction in the broken loop continued, causing the degradation of decay heat removal, the peak cladding temperature (PCT) would be expected to exceed the limit criteria for ensuring nuclear fuel integrity. However, despite the same total number of ruptured u-tubes, because of the different connection configuration between the SG and pressurizer, a difference is foud in time between the pressurizer low-level signal and reactor header low-pressure signal, affecting the time to trip the reactor and to reach the PCT limit.
The present study is expected to provide the technical basis for the accident management strategy for mSGTR transient conditions of CANDU-6 plants.

참고문헌 (Reference)

1 유선오 ; 조민기 ; 이경원 ; 백경록, "중수로 원전 교류전원 완전상실 사고 시 일차측 열수송 펌프 밀봉 누설 영향에 대한 코드 분석" 한국압력기기공학회 16 (16): 11-21, 2020

2 유선오 ; 이경원 ; 백경록 ; 김만웅, "중수로 원전 가상의 mSGTR과 SBO 다중 사건에 대한 MARS-KS 코드 분석" 한국압력기기공학회 17 (17): 18-27, 2021

3 IAEA, "The Fukushima Daiichi Accident" International Atomic Energy Agency 2015

4 KINS, "MARS-KS Code Manual" Korea Institute of Nuclear Safety 2021

5 OECD, "Five Years after the Fukushima Daiichi Accident: Nuclear Safety Improvements and Lessons Learnt" Nuclear Energy Agency 2016

6 KHNP, "Final Safety Assessment Report of Wolsong 3, 4 units" Korea Hydro & Nuclear Power Co., Ltd 2022