Uncertainty propagation in Pu isotopic composition calculation by gamma spectrometry: theory versus experiment

Abstract

Abstract Calculation and reporting of total uncertainties are essential criteria in the nuclear industry since measured results are used in decision making. Plutonium isotopic compositions (Pu IC) in different matrices are required at various stages of a close-loop nuclear fuel cycle. Under- and/or over-estimating uncertainties in Pu IC may result in avoidable radiological emergencies. In this work, we present the uncertainty budget for Pu IC determination using 120–450 keV gamma emission lines recorded with an HPGe. Detailed uncertainty propagation equations based on the propagation of partial derivatives are constructed and solved. Effects of the individual uncertainties on the total uncertainty are studied for different counting durations starting from 5 min up to 24 h. Results are compared with TIMS results and the theoretically calculated uncertainties were verified with multiple experimental data.