Hydrogen concentration variation and examination of PAR installation in reactor containment building during hydrogen release from different direction failure places

Concentration on a hydrogen explosion mitigation strategy increased after the accident in Fukushima. A passive autocatalytic recombiner (PAR) is considered as the most realistic mitigation technology during a severe accident where electric power is lost. Hydrogen distribution and concentration might be accurately predicted because PAR must be installed in a place having a proper amount of hydrogen in order to produce positive performance. In this paper, hydrogen distributions and concentrations were predicted and analyzed during hydrogen release from different direction failure places, and then PAR installation was examined. The result shows that the hydrogen concentrations are randomly changed in the containment overall, and the behavior of hydrogen in the case of upper part failure is completely different from the case of a side part failure. It is expected that PAR works well in the area among small compartments located at the lower part of the containment building; however, the performance of PAR installed on another area is inferior.