DETECTION OF ALPHA-EMITTERS IN SOLIDIFIED RADIOACTIVE-WASTE

According to the German ''Richtlinie zur Kontrolle radioaktiver Abfalle'', the specific activity of waste nuclides has to be declared if specific limiting values are exceeded. An example of these values is 130 Bq/g for Pu-239/240. This paper describes checks on alpha emitters in waste at the above mentioned activity level. Cemented waste products are dissolved in nitric acid. These solutions are well suited for subsequent solvent extraction. U and Pu are extracted by an organic TOPO-heptane phase from the acid liquid solution, and after neutralization Am and Cm are extracted from an almost neutral solution. The extractions can be counted in the liquid scintillation counter, e.g. for the determination of Pu-241, and with a gamma detector. Counting samples for alpha spectroscopy are prepared from the original solution and from both extractions by drying and evaporation. Uniform counting layers are obtained from the TOPO solutions by controlled heating of the planchet from the rim. The resolution of the alpha peaks from these extractions is better than 100 keV. The activity from different extractions is compared with the original solution to confirm the results.