SUBCOOLED BOILING AND VOID FLASHING IN A NATURAL CIRCULATION SYSTEM AT HEATING REACTOR CONDITIONS

This paper describes a calculational and experimental investigation of subcooled boiling and void flashing in a natural circulation system. A one-dimensional two-phase flow drift model with four governing equations was used for the analysis. Inlet subcooling and system pressure are varied as parameters. For comparison, a simplified model, which is based on saturated boiling only, was also used. The results show that subcooled boiling and void flashing may have great influence on the distribution of the void fraction and on the mass flow rate of the system, and that subcooled boiling and void flashing are more intense at lower system pressures than at higher pressure.