Improving Twin Calorimeter Designs with Heat-Flux Sensors

Heat-flow calorimetry provides a precise measurement of the thermal power produced by a radioactive source. When combined with isotopic analysis, the thermal power can be used to determine the mass of nuclear material. Calorimetry is used to obtain accurate measurements for plutonium material accountancy and is a primary non-destructive assay for plutonium. Current calorimeter designs have an accuracy of 0.5% to 0.1% in most cases. By replacing precisely wound nickel wiring as the arms of a Wheatstone bridge with heat-flux sensors, modifying the internal geometry of the calorimeters, and altering the insulation, this new twin calorimeter design aims to improve measurement stability and sensitivity including by reducing the effects of source weight and room temperature fluctuations. This design simultaneously aims to minimize the footprint required for the instrument and to improve its manufacturability and long-term serviceability by replacing difficult to produce and service custom components with off-the-shelf components or components with simpler manufacturing processes.