Preliminary Evaluation of Hydrogen Risk for Pressurized Heavy Water Reactor Using MELCOR Code

Abstract

Hydrogen behavior is a significant issue for the severe accident management. Various researches have been performed to confirm the risk of hydrogen behaviors such as generation, distribution, combustion, and mitigation in the containment building for light water reactors. However, only few studies have been performed for the pressurized heavy water reactors (PHWR) regarding hydrogen risk analysis. In this study, the hydrogen behavior of the PHWR under the postulated accident of station black out was investigated using MELCOR 2.1 code. The reference PHWR was Wolsung Unit 1 and initial sources of hydrogen, steam, and water released into the containment building were obtained from the ISAAC code results. The hydrogen behavior was analyzed for with and without operation of the Filtered Containment Venting Systems (FCVS). The hydrogen explosion occurred in the containment for two cases. The maximum pressure of the containment building approached the limitation of the containment failure (0.517MPa). The containment maintained the integrity when the FCVS operated without a hitch.