An Alternative Method to Mitigate the Hydrogen Challenge in Severe Accidents at a Nuclear Power Plant

Power systems and electric network

Abstract

Mitigation of hydrogen challenge is one of the basic goals of severe accident management at a NPP. The main measures for hydrogen control are inertization of the atmosphere and removal of hydrogen. Most of the commonly used strategies for hydrogen removal is based on the use of Passive Autocatalytic Recombiners (PAR) of hydrogen. The analysis of PAR operation specificity reveals that in some scenarios PARs can turn out to be not efficient and reliable enough. The efficiency of the hydrogen removal system will depend on the strategies used, the accident scenario and many different factors. A conclusion is made that the hydrogen mitigation strategy should consist of a combination of different strategies (e.g., PARs with venting) to be more flexible in hydrogen challenge management, and efficient and reliable in a broad scope of accident scenarios. The authors of the paper propose a new alternative method for coping with the hydrogen challenge. The concept and advantages of the method (strategy) are presented. The strategy is more applicable, but not limited for the PWR power plants having big dry containments. The proposed strategy, besides mitigation of hydrogen challenge, also ensures the removal of aerosols from the containment atmosphere, as well as heat removal from the containment as opposed to the operation of PARs, which is in line with the main goals of the severe accident management.