Self-protection of fast lead-cooled reactors against the partial blockage of the core flow area

Abstract

An analysis of the consequences for an accident caused by the blockage of the core flow area is of particular importance for the safety of metal-cooled reactors. A blockage may be caused by the release of slag accumulated in the primary circuit due to the violation of the coolant technology. In order to identify the self-protection margins of BREST-OD-300 and BR-1200 reactors, a comparative analysis of the consequences was carried out for an accident caused by the partial blockage of the core flow area. The velocity and temperature of the coolant in the core, as well as the temperature of the fuel and fuel element claddings during the blockage of the fuel assembly inlet was calculated using the SVIR 3D thermal-hydraulic code. Both reactors were demonstrated having high self-protection against the accident caused by the blockage of the most flow area at the core inlet. Thus, BR-1200 and BREST-OD-300 fuel elements maintain gas integrity until the inlet flow areas of 12 and 40 fuel assemblies is blocked, respectively.