Year
1990
Abstract
Calorimetry is an important non-destructive technique for the measurement of plutonium bearing samples. The technique has advantages over other measurement methods in that it is not biased by sample inhomogeneity or the presence of moisture and it does not suffer from neutron multiplication effects which can lead to errors with passive neutron coincidence counting. In the present paper the performance of the JRC Ispra (EURATOM) prototype transportable isothermal plutonium calorimeter is described. The device, which is intended for use by EURATOM safeguards inspectors, has been evaluated using a wide range of PERLA and Mound Laboratory plutonium heat standards. The dynamic measurement range of the instrument of up to 50 Watts has been covered with samples varying in power from 4 Watts to 37 Watts. The effects of varying lengths of preheating have been investigated as has the effects of different sample - calorimeter thermal coupling. The measurement precision has been determined and a preliminary determination of the heat distribution error has been made using heat standards. A measurement accuracy of better than 0.5 % has been determined using the decay corrected heat standards. Measurement times using sample preheating ranged from two to four hours depending on the thermal properties of the samples being measured.