Utilization of calorimetry for determining accurately a mass of Pu

Error calculations are discussed and the formula relating the mass determination of a plutonium sample to the response of a calorimeter and to the knowledge of isotopic composition and specific powers are established. It is shown how the uncertainty on the mass is related to the incertainty on the measurement of the power produced by the sample and to the weighted uncertainties on the concentrations and specific powers of the different isotopes. The various parameters and results of error calculations are then studied in detail. They show that by calorimetry it is possible to determine the mass of plutonium in a sample with an accuracy of about +-1%, at a 95% confidence level, for isotope 239 concentrations ranging from 98 to 8%, on condition that an accurate isotopic analysis is available