C. If the sample read less than 60 pCi/g in 24lam activity it was logged in and processed according to the general sample preparation procedure. For gross alpha measurement the sample was stirred with a disposable spoon and an arbitrary portion of soil was removed and dried. About 50 g of the dried soil, representing an infinite thickness, was spread evenly in an AC-3 plastic holder; then a spacer was emplaced and the sample was counted for gross alpha activity using an Eberline AC-3 Probe. A. B. If the gross alpha activity read above 400 pCi/g the sample was handled as a "high" level sample. If gross alpha activity read below 400 pCi/g the sample was processed according to general sample preparation procedures. After completing the general sample preparation, another 50 g aliquot was spread on an AC-3 plastic holder and an alpha measurement made as a double check prior to processing the sample through the wet chemistry lab. Sample preparation for plutonium, americium, strontium, and uranium chemistry required the aliquot to be ashed in a muffle furnace at 700°C for 12 hours. Aliquoting samples for chemistry analysis followed these criteria: a) 5 g aliquots were taken if gross alpha activity was less than 100 pCi/g; b) 1 g aliquots were taken if gross alpha activity was greater than 100 pCi/g but less than 400 pCi/g. Aliquots of 100 g were taken for gamma scan, sealed in a petri dish (100x20mm) and the lid secured with tape. This sample geometry was used for beta counting using an HP-210 Beta Probe with a thin screen of plastic between the sample and the detector. After all analyses were completed the samples were placed in the original cans and taken to the sample storage area. 4.3.3 Radioisotope Counting and Calculation Counting Radioisotope counting at. the RADLAB was designed for specific and gross measurements techniques. Counting for 238py, 239,240py, 24lam, and 2384u, 255y and 288U was completed using an ND 600 pulse height analyzer with four ORTEC silicon surface barrier detectors. The average performance rating for the semi-conductor detectors gave a FWHMresolution of about 45 keV with efficiencies of about 25 percent using a 239 py electroplated alpha standard. (See alpha efficiency records in the microfiche.) This alpha spectrometer covered a range of about 3.8 to 6 meV with 500 channels devoted to each detector. The 9%Sr concentration was determined by the measurement of its yttrium-90 (99Y) daughter. The Y was counted in a Canberra low background beta counter. efficiency of about 40 percent based on a The Canberra counter had a beta Osr souree and a background of less than 1.0 epm. The Sr internal tracer was determined by measuring the gamma energy on an ND 600 PHA with a coaxial intrinsic germanium detector. Swipes and air particulate samples were counted in one of several units depending on the size of the sample. Swipes and air particulate filters smaller than a two-inch diameter were counted in an Eberline scintillation alpha counter; samples larger than a two-inch diameter were counted in an Eberline large-area alpha counter and/or in the large-area beta counter. Plots of the background and efficiency data for the alpha and beta detectors appear in Figures 4-9, 4-10, 4-11 and 4-12. Calculation The radioactive concentration of the specifie radionuclide was determined by use of the appropriate equation as presented below. The 20 error term, at the 95 percent confidence level, associated with each of the results was included in the final calculation. The specific calculations were programmed on magnetic cards for use in an HP-97 desktop calculator. The final analytical results were reviewed and approved by the EIC laboratory managerprior to submittal to DOE/ERSP and DRL. 125