Development and Verification of MAAP5.0.3 Parameter file for APR1400

After the Fukushima accident, EPRI has continuously upgrade the MAAP5 (Modular Accident Analysis Program version 5) that is expected to expand the limitation of MAAP4. As a result of those efforts, the MAAP5.0.2 (Build 5020000) was released officially in December, 2013. Also, in August, 2014, the newest version of MAAP5, MAAP 5.0.3 (Build 5030000), was officially released. The parameter file development is essential for severe accident analysis using MAAP code for specific plant. In 2014, KHNP developed the first draft version of MAAP 5.0.2 parameter file for APR1400 type NPP and had tested for some basic severe accident sequence. And, until now, KHNP has continuously complemented the first draft version of APR1400 type NPP parameter file for MAAP 5.0.2 and 5.0.3. In this study, we analysis the MCCI phenomena using MAAP 5.0.3 version with the 2''n''d draft version of APR1400 parameter file developed by KHNP. The purpose of this study is to compare the major difference in MAAP 5.0.2 and 5.0.3 MCCI model and to verify the appropriateness of the 2''n''d draft version of parameter file. The MCCI phenomena have been controversial issues in the severe accident progression, so there have been great efforts to solve them until now. As the part of these efforts, EPRI published MAAP 5.0.3 version which is known that the 'Lower head plenum model' and the 'MCCI model' was upgraded. KHNP have the plan in order to upgrade the old parameter file based on MAAP4 to that based on MAAP5.0.2 or higher version for all domestic nuclear power plants. So, we have continuously developed the MAAP 5.0.2 and 5.0.3 parameter file for APR1400 type NPP. In this study, we analyzed the MCCI phenomena using MAAP 5.0.3 and 2''n''d draft version parameter file. And we found some insight as belows; (1) The Melt Eruption Model can greatly affect the MCCI progression only in the case of limestone concrete in the wet cavity condition. (2) In the wet cavity condition, the large amount of off-gas generated in MCCI became the main factor for the faster containment failure even though the BMT can be mitigated. (3) In the dry cavity condition, the BMT should be happened even though the containment failure cannot happen during the mission time. (4) In the case of basaltic concrete in the wet cavity, both the BMT and the containment failure due to overpressurization are the threat for the containment integrity