A critical evaluation of different isotope correlations for the determination of 242Pu

Different correlations are evaluated for the determination of 242Pu in Pu generated from PHWR reactors with an average burn-up of about 10,000 MWd/TU. It is shown that the correlations involving ratios of Pu isotopes, except for 241Pu, provide data with better confidence compared with those involving the atom% abundance. These correlations are also attractive when the decay period of the given sample is not known. In addition, it is shown that instead of using 239Pu atom% abundance alone (Swinhoe et al., 2010), either 240Pu atom% or a linear combination of 239Pu and 240Pu gives abundance of 242Pu with better reliability. The uncertainty due to different decay periods also remains unaffected when using the correlation involving both 239Pu and 240Pu atom%. The present conclusions are based on Pu isotopic composition data from PHWR reactors (239Pu 65–75%) whereas those reported by other investigators are for PWR and BWR types of reactors.