Alpha spectrometry and liquid scintillation counting for the measurement Pu-238, Pu-239, Pu-240, Pu-241, Pu-242 and age

A method for the measurement of the isotopic composition and time since last chemical separation (age) of plutonium is presented. The method includes alpha spectrometric measurement of Pu-238, Pu-239 and Pu-240 where the ratio of Pu-239 and Pu-240 was determined using spectral deconvolution, and liquid scintillation counting of Pu-241, after chemical separation of plutonium and americium. For the age determination, the Pu-241 determined using liquid scintillation counting was combined with alpha spectrometric measurement of Am-241. The results of the isotopic composition were compared with certified reference materials with known isotopic composition, and the results of the age determination were compared with literature values of the separation dates.