Study on Heat Transfer Behavior of a Rectangular Particle Bed With Volumetric Heating

Abstract During core disruptive accidents (CDA) in sodium-cooled fast reactors, the core debris bed could be formed due to the interaction between the molten fuel and coolant. At the late stage of CDA, the heat removal of decay heat will be achieved mainly by the natural circulation of the molten stainless steel to the surrounding environment. To investigate the coolability of fuel debris bed, a rectangular experimental system was built in which the particle bed was volumetrically heated via direct current heating. The experimental apparatus consists of a Nd-Fe-B magnetic particle bed immersed in water and a water pool above it, which simulate disrupted solid fuel and molten steel, respectively. Magnetism ensures the good contact between particles; therefore, the stable volumetric heating is truly achieved, which is similar to the characteristic of fuel debris with internal decay heating. Computer code simulations with the reactor safety analysis code SIMMER-IV were performed to help understand the heat transfer characteristics and to validate the applicability of the newly embedded momentum exchange function (MXF) models. The time variation of average temperatures of particle bed and water pool, and their difference were evaluated to compare with the experimental results. The comparison results show the most applicable MXF model under current experimental conditions and well reproduce the influence of water pool height in the experiments.