Estimation of equivalent conductivity of porous debris bed

The particulate debris bed formed during the course of severe accident is a complex porous formation. The thermal behaviour of the bed depends on nature contact between the particles and degree of consolidation. For the analysis of the macroscopic heat flow through the bed, the local volume-averaged (or effective) properties such as effective thermal conductivity are used. The contact resistance between the non-consolidated particles, i.e., the solid surface oxidation and other coatings are all crucial. The analytical modelling of the equivalent conductivity depends on the topology of inter-particle contact, degree of consolidation, conductivity ratio of the matrix and the fluid. A number of models have been examined for prediction of equivalent conductivity. Their limiting behaviour have been analysed to asses the applicability for a different configuration of the porus bed. (author)