Analysis Method for Licensing Application of Passive Autocatalytic Recombiner System as a Hydrogen Mitigation System of OPR-1000

As a result, for some plants, dual hydrogen mitigation systems are prepared with a combination of PARs and igniters that each system has a 100% of full capacity for hydrogen control for postulated severe accident conditions. In the original design of OPR-1000, hydrogen mitigation systems consist of a thermal recombiner and twenty glow-type igniters, which are used for design basis accident and severe accident, respectively. This paper presents an analysis method for licensing application in Korea to determine the capacity and locations of PARs for the design of a hydrogen mitigation system with PAR. A licensed analysis method of OPR-1000 has been presented to determine the capacity and locations of PAR for the design of a hydrogen mitigation system with PAR. A lumped parameter code of MAAP 4.0.6+ has been adopted to simulate various severe accident scenarios with a 26 multi-compartment containment model. Hydrogen generations were analysed and required capacity and locations of PAR were determined for six accident scenarios selected from a combination of probabilistic and deterministic considerations. A total of twenty-four PARs in the containment dome, steam generator rooms, annulus and adjacent areas was designed and the adequacy of this system has been confirmed through detailed analyses including sensitivity analyses with/without operations of safety systems such as containment heat removal systems, reactor coolant depressurization system and safety injection by accumulator, etc. Through the assessment on the possibility of global FA and DDT, it has been concluded that new PAR system with twenty-four recombiners can remove hydrogen effectively in the containment atmosphere and prevent from global FA and DDT. Further works are required in the future to develop a well-balanced analysis methodology with a combination of lumped and CFD tools focusing on the optimum locations of recombiners and local hydrogen behaviour in containment compartments