DC-1 and DC-2 debris coolability and melt dynamics experiments

The DC experiment series investigates the heatup and melt of dry reactor core debris through nuclear heating of actual reactor materials in order to obtain the thermal properties of dry debris, the nature of the transition from a debris bed to a molten pool, and the thermal and kinetic behavior of molten pools. The purpose is to develop a data base in support of model development. This report provides a description of the two experiments in the DC series and documents the configuration and the data. These tests investigated dry debris beds (approx.2 kg) composed of pure UO2 and mixed UO2 and stainless steel. Heat transfer characteristics were studied at several steady-state conditions below melt. The beds were then taken into melt to observe the growth of a molten pool in the UO2 bed and the agglomeration and migration of steel in a composite bed. The peak measured temperature in the UO2 bed above 30000C. Approximately 50% of the urania formed a molten pool. In the mixed UO2 and steel bed, the peak measured temperature was 26000C. With about 90% of the steel molten, material migration occurred resulting in a significant increase in the gross bed thermal conductivity