Examination of the Coping Strategies (FLEX) of APR1400 for Extended Station Blackout using MARS Code

다국어 초록 (Multilingual Abstract)

Since the Fukushima Dai-ichi NPP accident, the Korean regulatory agency as well as the US NRC have strengthened the SBO mitigation capability for all operating and new reactors as a part of the defense-in-depth measure. In this paper, the multi-dimensional analysis of reactor safety (MARS) code is used to model APR1400 under the extended SBO condition. A thermal hydraulic analysis is undertaken to ascertain the plant's coping capability for up to 72 hours if a set of diverse and flexible coping strategies (FLEX) is implemented as proposed by the American nuclear energy institute, NEI[1]. Notably, for the extended SBO, the RCP seal leakage is an important yet uncertain parameter that may significantly affect the thermal hydraulic response of the plant. Given the significance and uncertainty of the RCP seal leakage rates on the plant's response, a parametric study is conducted for different leakage rates. The plant's response to the extended SBO with attendant RCP seal leakage solely relying on the existing equipment is first examined. Subsequently, an optimized coping strategy using the additional FLEX equipment (primary-side and secondary-side external injection) is developed with different RCP seal leakage rates for up to 72 hours into the accident.

참고문헌 (Reference)

1 U.S. NRC, "Recommendations for Enhancing Reactor Safety in the 21st Ceontury"

2 Westinghouse, "Reactor Coolant Pump Seal Leakage Model for Westinghouse PWRs"

3 TEPCO, "Overview of the Earthquake &Tsunami and Nuclear Accident: The Great East Japan Earthquake and Current Status of Nuclear Power Stations" 2011

4 KAERI, "MARS code manual"

5 Lee, S.W, "Extended Station Blackout Coping Capabilities of APR1400" 2014 : 2014

6 Kim, W.B, "Extended Station Blackout Analyses of an APR1400with MARS-KS" 31 (31): 318-326, 2016

7 Eom, S, "Examination of SBO Emergency Operating Procedure of APR1400 using MARS code" 2017

8 NEI, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide, Rev.4"

9 Hwang, J.R, "Developing Optimal Procedure of Emergency Outside Cooling Water Injection for APR1400 Extended SBO Scenario Using MARS Code" 2013

10 KEPCO, "APR1400 Design Control Document Tier 2"