Year
2017
Abstract
The precise determination of the amount of nuclear material within a container has long been a challenge, and especially with complex matrix and lack of homogeneity. A measurement approach combining calorimetry, gamma spectrometry and radiological modelling will be presented as an integrated nuclear material characterization system. Calorimetry is one of the best solutions to determine the overall quantity of nuclear material on a wide range of mass, from a few milligrams up to kilograms of radionuclides. It has many advantages as it features a non-destructive method which remains independent of matrix effect or the chemical composition. Modern technological developments within the calorimetry field give the promise of faster measurement times and precise measurements with low levels of uncertainty. Gamma spectrometry allows the determination of the isotopic abundance to qualify precisely each radionuclide. Until now, calorimetry allows to measure at the lowest 0.5 to 1 mW for samples but nowadays, thanks to new technological breakthroughs, KEP-Technologies calorimeters are able to measure as low as 50 µW for 40 liters samples and less for a few liters containers. This new calorimeter named µLVC is based on a new design with twin cells, a new temperature regulation loop and a heat-flow measurement system inside a vacuum chamber (Patent deposit P005299 LA/VL). The µLVC is a differential heat-flow calorimeter for precise measurement independent of the residual fluctuations caused by environmental changes. The new calorimeter is an industrial product able to work in environmental conditions with wide temperature variations. Its software is friendly user and allows measurement time optimization and uncertainty calculation. A device combining calorimetry and gamma spectrometry is designed as a new tool for quantification of nuclear material to characterize Pu-Am samples, i-graphite, and low tritium samples with high precision and reliability.