Determination of 242Pu by correlation with 239Pu only

Correlations are used to determine the 242Pu content of material using high resolution gamma measurements on the other plutonium isotopes because 242Pu itself has no practically detectable gamma emission lines. This paper presents an improved correlation that is particularly useful because, unlike some previous correlations, no prior knowledge of the reactor type or initial enrichment is required. This correlation has been shown to perform well over a range of plutonium from commercial BWR and PWR reactors. The agreement of the calculated 242Pu values with IDMS values is within 1% for 239Pu content of less than 70% and within 4% for 239Pu content of less than 80%. This simple form of the correlation is somewhat surprising given the complex behavior of 239/240 and 242/240 ratios.