ABSTRACT
This chapter presents the results of an experimental study that addresses several aspects of the coolability question with emphasis on the effects of pressure and flow from below. The pressure effect is studied in the chapter over a range sufficient to cover much of the range needed to evaluate severe accidents. Flow from below can also significantly impact on the dryout heat flux. The effect of flow is studied in the chapter to see how much forced flow should be provided to avoid dryout. The experimental results show that the dryout heat flux increases very rapidly with pressure when the reduced pressure is small. The gases from core-concrete interactions may lower the dryout heat flux dramatically and lead to remelting of the core debris. Multi-dimensional dryout heat flux is mainly controlled by the resistance of the heated particles. Gas flow from below decreases the dryout heat flux. The decrease in dryout heat flux is monotonic with increasing gas flow rate.
