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 w eapons test sites in Australia have used the 59.5 keV gamma ray from t he Am-241 impurity to estimate levels of (239)pU and (240)pU. Measurem ents of the activity ratio of (239)pU to Am-241 are presented for site s where suitable samples could be collected. Measurements of (240)pU w ere also made when interferences from fission products were absent. Al l measurements were made using a planar Ge detector of sufficient reso lution 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 5 9.5 keV Am-241 gamma ray. Results are given for most of the plutonium- contaminated sites in Australia.