Heat-transfer characteristics of dry porous particulate beds with internal heat generation

A combined experimental and analytical program was undertaken to study the thermal characteristics of dry debris beds especially at high temperatures where radiative heat transfer contributes. Experiments were conducted in-pile using intrinsic fission heating of UO2 to simulate decay heat power levels. Both pure UO2 and mixed UO2/steel beds in a helium atmosphere were studied. Temperatures as high as 3100 K were attained. Thermocouples and ultrasonic thermometers were used to measure the bed temperatures. Also recent post-test metallographic examinations have revealed useful information on the materials interactions which can be correlated to changes in the thermal behavior of the bed. In addition to the experiments, a number of porous medium thermal conductivity models were evaluated. From these, two models representing upper and lower bounds for the conductivity, in conjunction with a two dimensional heat transfer analysis were compared to the data.