Year
1970
Abstract
A plutonium reactor fuel inventory can be verified as reliably by gamma ray measurements as by conventional chemical-mass spectrometric techniques. A recent evaluation of the comparative reliability of assay of plutonium reactor fuel by destructive (chemical-mass spectrometry) or nondestructive (gamma ray spectrometry) techniques indicated that the measurement uncertainties associated with each case were nearly equivalent. This evaluation resulted from a numerical analysis of measurements made of 725 plutonium alloyed metal fuel plates. Every plate was assayed for Pu-239 and Pu-241 by the gamma ray spectrometry technique and 189 chemical- siass spectrometry analyses were made of the material from which the plates were fabri- cated. These two sets of measurements were used to determine the total quantity of material. The totals differed from each other by only three parts in 25,000 and the measurement error was established as about two parts in 1,770 for each case. This close agreement was possible despite the fact that the uncertainty of a single chemical-mass spectrometry measurement was ^ 1.8% as compared to jf 3.0% for a single plate measurement by the gamma ray technique.