Simulation of Ignalina NPP accident localisation system behaviour employing the RALOC4 code in the case of group distribution header rupture Original Research Article

The response of the RBMK Accident Localisation System (ALS) to a medium break LOCA (group distribution header (GDH) rupture) is analysed employing the RALOC4 code. The analysis employs a best estimate mass/energy source and considers both short and long-term (up to 24 h) responses of the ALS. The main long-term energy sources and sinks are taken into account and modelled in detail in this analysis. The technical systems connected to the ALS are taken into account and modelled in detail in this analysis in order to achieve correct mass and energy balances. The analysis results demonstrate that the pressures in the ALS compartments are below the maximum allowed design pressures in the case of GDH rupture.