Analysis of hydrogen control in severe accidents of CANDU6

After Fukushima accident, hydrogen control system reliability evaluation is implemented for most of nuclear power plants around the world. For early CANDU6 design, there is no hydrogen control system used for severe accidents. For CANDU6 hydrogen control in severe accidents, accept criteria is different with PWR. Consideration of deuterium is discussed. CL4, LLOCA and FBS are selected as typical severe accident sequences. Hydrogen concentration and hydrogen risk without mitigation are investigated. With the analysis base of hydrogen behavior without mitigation, 18 passive autocatalytic recombiner (PAR) is located into containment compartments. According to analysis results, hydrogen concentration is controlled below 10% during accidents, hydrogen risk is eliminated.