Sensitivity analyses on hydrogen generation for KNGR using MELCOR

The amount of in-vessel hydrogen generation during severe accidents affects the integrity of containment. For the Korean Next Generation Reactors, sensitivity analyses on the in-vessel hydrogen generation are described. The typical accident sequences of a station blackout and a large LOCA scenario are selected. A lower head failure model, a Zircaloy oxidation reaction model and a B4C oxidation reaction model are considered as the sensitivity parameters. As for the base case, 1273.15K for a failure temperature of the penetrations or the lower head, an Urbanic-Heidrich correlation for the Zircaloy oxidation reaction model and the B4C oxidation reaction model are used. The results of the studies are summarized below : (1) When the penetration failure temperature is higher, or the creep rupture failure model is considered, the amount of hydrogen increases for two sequences. (2) When the MATPRO-EG and G correlation for a Zircaloy oxidation reactor is considered, the amount of hydrogen is less than the Urbanic-Heidrich correlation (Base cae) for both scenarios. (3) When the B4C reaction model turns off, the amout of hydrogen decreases for two sequences