Enthalpy and heat capacity of liquid plutonium and uranium

The enthalpy and effective heat capacity of delta-plutonium and oralloy have been measured at temperatures high in the liquid region. The Super Kukla prompt-burst reactor was used to heat thin wafers of these metals by neutron-induced fission. The temperature increase in the samples was measured with thermocouples and the number of fissions in the sample determined radiochemically. From these data, heat capacity and enthalpy were calculated. The heat capacity of oralloy was calculated as 159 J/kg.0C up to 22000C. A constant value of 180 J/Kg.0C was computed for the effective heat capacity of liquid delta-plutonium up to 22000C. Because molten plutonium and uranium would chemically attack even the most refractory crucible materials, it would be very difficult to obtain such data by conventional laboratory calorimetry; it is believed that the use of neutron heating in these investigations is unique. (Auth.)