RAPID-DETERMINATION OF SR-90 IN ENVIRONMENTAL-SAMPLES BY SINGLE CERENKOV COUNTING USING 2 DIFFERENT COLOR QUENCH CURVES

The validation of the Cerenkov radiation measurement of Y-90 to determ ine the activity concentration of Sr-90 in environmental samples is de scribed, Liquid-liquid extraction with di-2-ethyhexylphosphoric acid i n toluene was used to separate Y-90 from Sr-90, Optimum conditions for Cerenkov counting (low-level counting option, counting windows, mass of solution to be measured) were established, The need for a counting efficiency correction by using a colour quench curve is stated to be e ssential, otherwise a significant error may occur, Two different colou r quench curves (counting efficiency versus the channel ratio or spect ral index parameter) were used and the results were compared, The meth od was applied to 12 environmental matrices: sea-water, algae, carobs, milk, almonds, hake, honey, shellfish, lamb meat, sardine, pork meat and shore sand, No significant differences were observed on using eith er of the two colour quench curves for any of these environmental matr ices, In order to validate the proposed method,a certified soil refere nce material (CRM IAEA-375) was used, together with participation in a n interlaboratory exercise to determine Sr-90 in a natural water sampl e. Again, efficiency correction was performed by using either of the t wo colour quench curves and in both instances the calculated Sr-90 act ivity concentration was in good agreement with the known values.