DETERMINATION OF THE RATIOS OF PU-239 AND PU-240 TO AM-241 FOR NUCLEAR-WEAPONS TEST SITES IN AUSTRALIA

Recent measurements of the plutonium contamination at former nuclear weapons test sites in Australia have used the 59.5 keV gamma ray from the Am-241 impurity to estimate levels of (239)pU and (240)pU. Measurements of the activity ratio of (239)pU to Am-241 are presented for sites where suitable samples could be collected. Measurements of (240)pU were also made when interferences from fission products were absent. All measurements were made using a planar Ge detector of sufficient resolution to separate the 51.6 keV (239)pU gamma ray from the Ge K x-ray escape peaks and Compton scattering continuum from the much stronger 59.5 keV Am-241 gamma ray. Results are given for most of the plutonium-contaminated sites in Australia.