Fast source preparation for alpha-spectrometry of uranium and transuranium isotopes

Abstract

A very fast and simple source preparation procedure for α-spectrometry, especially for the Large-Area Grid Ionization Chamber, has been developed. It is based on two liquid-liquid extractions and direct evaporation of the extractants, containing the uranium and transuranium isotopes, on the counting dishes. From the sample two thin-layer counting sources are prepared to take into account the α-spectrometric interference of the nuclides234U−237Np and238Pu−241Am, where one counting source contains the U- and Pu-isotopes and the other one the Np- and Am-isotopes. The chemical yields are in the range of 95 and 98% so that no yield tracers are necessary. Starting with the dissolved sample, the two counting sources can be prepared in only about 1 hour. A second even faster preparation version, with only one counting source, has been devised, if discrimination of the interfering nuclides mentioned above is dispensed with. This version can also be used for gross α-activity measurements in a liquid scintillation counter. With the preparation procedures described here the sample volume is limited to 1 ml. Therefore it is preferably applied to medium-active samples from nuclear power plant waste stream, but it can also be used for low-level environmental samples after suitable preconcentration procedures.