Effective water cooling of very hot surfaces during the LOCA accident

Abstract

The quench front propagation in the case of the water emergency cooling of water cooled fusion nuclear components is studied during the LOCA accident. In the case of the LOCA accident, heat removal can be successful only when water rewetts the surface. The place where water meets the very hot surface is called the quench front. The quench front propagation depends on the initial wall temperature, coolant flow rate, and heat accumulated in the cooled components. Results of the quench front experiment in an annular 1.7m length channel with initial wall temperatures within the range from 250°C up to 800°C and coolant mass fluxes 100kg/m2s and 180kg/m2s are presented. From the results is concluded, that quenching velocities and rewetting temperatures are strongly dependent on the initial wall temperature as well as the pressure spikes. The behaviour of the heat transfer coefficient at the quench front is analyzed.