Year
2003
Abstract
High precision small sample radiometric calorimeters are designed to make accurate measurements of small plutonium samples, of typically a few grams, in order to reduce the requirement for costly and time-consuming destructive assay (DA). The present paper describes preliminary measurements of the low power performance of an ANTECH small sample calorimeter, which was designed to support both IAEA and EURATOM safeguards non-destructive assay (NDA) measurements and measurement standards certification activities. The design characteristics of the instrument are described and the measurement performance (both precision and accuracy) is presented for a preliminary campaign of electric calibration sample measurements in the range from 10 microwatts up to 2 milliwatts. The instrument is transportable and employs a solid aluminum heat sink as the reference temperature environment, avoiding the need for a water bath temperature reference. Two identical measurement chambers (wells or cups) which are based on the use of thermopile technology, allow the calorimeter to operate in dual cell cup A minus B mode. The measurement stability and performance of the device have been improved through the use of new technology in the measurement instrumentation. The instrument is designed to operate using direct resistance measurement for temperature control. The instrument is equipped with an internal electric calibration system for which measurements of electrical power are traceable to NIST. As a result of the enhanced temperature control, improvements have been made in the performance of the prediction algorithms used for the sample equilibrium power determination. The results of these design efforts are presented. The calorimeter exhibited improved low power performance extends the operating range to include the measurement of low level pyrochemical salts. [1]