Thermal hydraulic analysis and design of the WWR-M2 nuclear research reactor – power upgrading

Abstract This paper presents the outline of the core thermal hydraulic design and analysis (Operational Safety Analysis) of the Budapest nuclear research reactor (WWR-M2 type), which is a tank-type, light water-cooled nuclear research reactor with 36% enriched uranium coaxial annuli fuel. The research reactor is currently upgraded to 10 MWth of thermal power, while the cooling capacity of the reactor was designed and constructed for 20 MWth. This reserve in the cooling capacity serves redundancy today but can be used for future upgrading too. The core thermal hydraulic design was, therefore, done for the normal operation conditions so that fuel elements have enough safety margins both against nucleate boiling anywhere in the reactor core. Thermal hydraulic performance was studied. It is shown that the 36% enriched UAlx-Al fuel elements in WWR-SM fuel coolant channel do not allow to force up the reactor power to 20 MWth. The study was carried out for an equilibrium core, with compact load (223 fuel assemblies) under normal operation conditions only (steady state condition).