SR-90 IN CORAL SOIL DOE/ERSP PROCEDURE NO. 23 APPROVED: I DATE DRAFTED: 17 January 1979 20 January 1979 by Ernie Campbell (ERSP Manager) Introduction This procedure does not depend on secular equilibrium between 90sr and 90y in the soil sample. Yttrium-90, 152Eu, 154Ey, 155pu, and 13%Cs are stripped away from the 9%sr. After a two week period to allow 90y ingrowth, the 99y will have reached 97% of its equilibrium value. At this point, the 90y is again stripped away and counted, Because the secular equilibrium is essentially complete, the 99Sr activity can be calculated from the measured 99Y activity. The second separation of 99y from 99sr ean be done after a shorter ingrowth period if a correction is made for incomplete 99y ingrowth. 18 Procedure A. Sample Preparation 1. Samples must be screened to select the proper aliquot size for chemistry. All samples to be analyzed for 90sr will be counted for gross beta after ballmilling. A 10 g aliquot will be used for samples which contain 200 pCi/g or less, For samples between 200 and 500 pCi/g, a 5 g aliquot will be used. For samples which contain greater than 500 pCi/g of activity, consult the EIC chemist for further instructions. B. 2. Weigh out the appropriate aliquot in a porcelain crucible and place in a muffle furnace and ash for 8 hours at 800°C. 3. Remove from furnace and allow to cool. The sample is now ready for chemistry. Ty, Separation (First Milking) 1. Transfer the sample into a 150 ml beaker with deionized water. Rinse the erucible three times with 10 ml portions of cone HNOs, and transfer each rinse to the beaker with swirling. Add 10,000 dpm 895sr tracer. Evaporate volume to about 5 ml. Add 20 ml cone HC! and evaporate sample to dryness. 2. Cool sample and dissolve in 10 ml of 0.08M HCl. 3. Transfer sample into a 40 ml conical centrifuge tube. Rinse beaker with two 10 ml portions of 0.08M HCl and transfer each rinse to the centrifuge tube. 4. Centrifuge for 10 minutes at 1800 rpm. 5. Transfer supernatant to a 125 ml separatory funnel. If a residue is present, wash 6. Add 30 ml of 20% HDEHP(v/v in toluene) and shake for two minutes. Allow the phases to separate and drain the aqueous layer into a second 125 ml separatory funnel. Discard the organic layer and rinse the first separatory funnel with 5 ml of toluene. 7. Add 30 ml of 20% HDEHPto the second separatory funnel, shake for two minutes and allow the phases to separate. Drain the aqueous layer into the first separatory funnel and discard the organic layer. with 5 ml of 0.08M HCl, recentrifuge and transfer supernatant to separatory funnel. A-23-1