Development and validation of CFD model for catalytic recombiner against experimental results

The damage caused to the containment of a nuclear reactor because of generation of hydrogen and its subsequent combustion has been evident in the few major nuclear accidents witnessed by the world so far. Deployment of Passive Catalytic Recombiner Devices (PCRDs) is being widely used to mitigate the hydrogen risk. Experimental and numerical studies are underway around the world to characterise such recombiner devices. CFD studies involving PCRDs are important to spatially and temporally resolve flow fields and hydrogen concentrations inside reactor containment. In the present work, the reaction kinetics evolved earlier for a catalyst device developed in-house has been empirically approximated as a single step Arrhenius equation. This kinetics has been implemented as a CFD based PCRD model. The detailed model resolves individual catalyst plates and simulates the surface reaction occurring at the fluid-solid interface along with conjugate heat transfer, thermal radiation and buoyancy induced turbulent flows inside the multi-species gas mixture. Simulation results of the model have been compared against in-house experimental data. The validated CFD model will be a useful tool for accurate quantitative prediction of specific PCRD performance inside closed geometries.