The state of validation of porous media debris coolability models

This paper describes a steady state model of boiling in a particulate bed which drew heavily on published material for multi-phase flow in a porous medium. The model gives reasonable agreement with measured dryout heat fluxes (the largest heat flux that can be removed when the debris temperature is restricted to the boiling point of the coolant). It also provides an explanation of the low dryout heat fluxes of stratified (fine over coarse particles) beds. Because of experimental variability it is not clear how well the model describes the detailed physical processes in the bed. A one-dimensional transient model for a packed bed at saturation temperature has been extended to included sub-cooled and dry regions. Transient calculations allow a more extended comparison of the model with experimental data such as time and position of first dryout, pressure and saturation histories, temperatures evolution in dry and sub-cooled regions, and quench behaviour