Hydrogen distribution and burning analysis following core melt down of a nuclear reactor using CONTAIN

Hydrogen distribution and burning inside the 1,000 MWe Korea Standard Nuclear Power Plant containment are analyzed using computer code CONTAIN. It is assumed that 100% of the reactor core is melted down and reacted with steam to generate hydrogen. MBLOCA and TMLB' cases are considered. For each case, hydrogen distributions are computed with and without containment spray and fan operation. Pressure, temperature and hydrogen concentrations of the 19 cells are computed for hydrogen burning. Although hydrogen mole fractions of certain cells reach the detonation threshold, detonation might not take place due to excessive vapor, excessive hydrogen and limitation of containment geometry. During hydrogen burning, peak pressure and temperature in the containment annulus region reach about 30.5 psia (210.3 KPa) and 2,017 F (1,103 C) respectively