Verification of the 239Pu content, isotopic composition and age of plutonium in Pu–Be neutron sources by gamma-spectrometry

A non-destructive, gamma-spectrometric method for verifying the plutonium content of Pu–Be neutron sources has been developed. Gamma-spectra were taken in the far-field of the sample, which was assumed to be cylindrical. The Pu content of the sources was evaluated from the count rates of the gamma-peaks of 239Pu, relying on the assumption that the gamma-rays are coming to the detector parallel to each other. The uncertainty components are studied in detail. It is also shown that the isotopic composition and the age of plutonium (Pu) can be determined in the intensive neutron field of these sources by the “multi-group analysis” method. The determination of the specific neutron yields is also discussed.