Hydrogen combustion during direct containment heating events

Abstract

Direct containment heating (DCH) has the potential to cause short-term overpressure failure of the containment in a nuclear power plant that has experienced a core melt accident. This paper addresses the possible modes of hydrogen combustion in the dome region of a pressurized water reactor containment building during a DCH event. The combustion modes considered are: combustion of hot hydrogen jets, deflagrations, volumetric combustion, and mixing limited combustion. The limits for each combustion mode are defined and interpreted in the context of both experiment and reactor applications. With the exception of jet combustion, heat transfer to structures can significantly limit the contribution of hydrogen combustion to peak containment pressures on the DCH time scale. Implementation of these hydrogen combustion models into the two-cell equilibrium model is discussed.