Determination of alpha activity ratios by alpha spectrometry in the presence of large amounts of uranium

A direct evaporation method is described for the preparation of sources using stainless steel as the backing material and tetraethylene glycol (TEG) as a spreading agent in the presence of large amounts of uranium. It is shown that FWHM and tail contribution at the low energy peak due to energy degradation of the high energy peak can be optimized by heating the source under controlled conditions in a furnace at 500-600 deg C for about 15 min. An accuracy of 0.5-1% is demonstrated for the determination of sup(238)Pu/(sup(239)Pu+sup(240)Pu) alpha activity ratio in the U/Pu range of 10 to 1500 generally encountered in dissolver solution of irradiated fuel. (author)