Simulation of the hydrogen distribution in the confinement of the Ignalina nuclear power plant

Abstract

Abstract The Accident Localisation System (ALS) of the Ignalina nuclear power plant is a “pressure suppression” type confinement, which protects the population, workers and environment from radiation hazards. According to the safety justification of RBMK-1500 reactors, ∼110 m3 of hydrogen is released to the ALS compartments during a maximum design basis accident. To prevent the possible hydrogen accumulation and combustion, a hydrogen concentration control system is installed. The main goal of the present paper is to present the ALS model for the COCOSYS code and assess the effectiveness of the hydrogen control system of the Ignalina nuclear power plant. The analysis performed identified locations of possible hydrogen accumulation in the ALS compartments during the transient processes and assessed the mixture combustibility in these locations for a maximum design basis accident scenario.