A Comparison on Application of MARS and RELAP5 to KINS Realistic Evaluation Methodology

The best estimate method with the uncertainty evaluation has been broadly used worldwide in licensing NPP. The KINS (Korea Institute of Nuclear Safety) has also conducted the regulatory audit calculation by using the KINS Realistic Evaluation Methodology (KINSREM). The RELAP5/MOD3.3 code has been used in KINS-REM. Currently, KINS has evaluated the applicability of the MARS code for KINS-REM, which is the major part of the development and application of reactor transient analysis system for regulatory audit (RETAS). Since the dialing method of MARS was different from that of RELAP5/MOD3.3 in considering the uncertainty parameters, the effect for the code change should be evaluated. The accident scenario is selected as the LBLOCA of APR1400. The objective of this study is to compare the results for MARS and RELAP5 that were obtained from the regulatory audit calculation. Also, the causes of the difference between results of two codes are identified