Year
1997
Abstract
There is a requirement for high precision calorimetry measurements of large volume plutonium samples for the re-calibration of Pu heat standards and as a substitute for some destructive assay measurements. The present paper describes the development and the design characteristics of a large sample plutonium calorimeter of high measurement precision and accuracy. The measurement stability and performance of the device have been improved through the use of new technology III the measurement instrumentation. The instrument is designed to operate either using traditional resistance bridge circuitry or 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 and illustrated using measurements from production calorimeter systems. The calorimeters exhibit a small bias, typically