A calorimeter for assaying radioactive material

The world-wide nuclear power programme entails the reprocessing of spent nuclear fuel, and quantities of recovered fissile plutonium and uranium must be safely and accountably stored. If, as is usual, the isotopic composition of the stored material is known, a precise measurement of the thermal power that it is producing enables the the masses of the active components to be determined, or assayed, since the specific powers of isotopes are tabulated. The calorimeter described has been designed to assay material in containers of sizes used by the International Atomic Energy Agency (IAEA) and the European Atomic Energy Agency (EURATOM). It is of the isothermal or replacement type, and is capable of measuring sample powers of up to 50W