Re-evaluation of NUPEC M-7-1 Hydrogen Experiment using MELCOR 1.8.6

Evaluation of hydrogen distribution in containment building is still of keen interests. KINS is evaluating the hydrogen risk for the continued operation of Kori-1 and also for the new reactors like Shin-Kori-1,2, Shin Wolsong-1,2 etc. Considering these needs and also that the code used in KINS is moving from MELCOR 1.8.5 to MELCOR 1.8.6, we have evaluated the NUPEC hydrogen test M-7-1 using MELCOR 1.8.6. The NUPEC test was chosen just because it is the only available data we have. We will continue to evaluate other experimental data of hydrogen once they are available. In NUPEC's Hydrogen Mixing and Distribution Test M-7-1, steam/helium mixture was released into the lower region of a simplified 1/4 scale model of large dry containment of 4-loop PWR(fig.1) to simulate break of a steam generator (SG) system. Total helium volume was decided by volumetric scaling of hydrogen released due to 100% Zr-H2O reaction. At the same time, containment spray was also activated to simulate the impact of spray water. Test containment had 25 compartments and 66 paths, and each compartment had measuring instruments for temperature (wall/air), pressure and helium concentration