Experimental Study on Cooling Characteristics of Mixed Particle Size Debris Bed under Different Water Injection Methods

The liquid core melt interacts with the coolant and breaks into a particle bed. Effective cooling of the particle bed can realize the retention of the melt and stop the accident process. In this paper, based on the particle size distribution and porosity of the fragments after the prototype molten FCI experiment, a mixed particle size sand debris bed with internal heat source was constructed, and the dryout characteristics of the debris bed under different enhanced heat removal measures (submerged pool at the top, water injection at the bottom driven by natural circulation, and circumferential water inlet) were studied. The results show that, under the condition of submerged pool at the top, the bubble clogging zone appears first in the middle and upper part of the debris bed, and then the liquid deficiency dryout zone appears in the middle and lower part of the debris bed. Under the condition of water injection at the bottom driven by natural circulation, the fluid deficiency at the bottom of the debris bed was greatly improved, and the dryout heat flux (DHF) increased by more than 2.5 times, the dryout area was located in the middle and upper part of the debris bed. Under the circumferential water inlet, DHF also increased by more than 2.5 times. © 2023 Yuan Zi Neng Chuban She. All rights reserved.