Hydrogen control using PARs and igniters

The KSNP+ design adopted Passive Autocatalytic Recombiners (PARs) for the hydrogen control in the reactor containment following DBA LOCA, to replace the conventional thermal recombiner. Although the PAR system is basically intended for design basis hydrogen control, it is also expected to function during severe accidents by the passive characteristics for hydrogen removal. The capacity and the number of PARs were determined to limit the hydrogen concentration below the flammability limit following a DBA LOCA. Then, the three-dimensional flow pattern analysis was performed using GOTHIC computer code to optimize the locations of PARs. Finally, the combined effects on the hydrogen removal by both igniters and PARs during severe accidents were also evaluated. The results showed that PARs could supplement hydrogen igniters effectively through long-term and continuous hydrogen removal during severe accidents. (author)