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MEMORANDUM FOR RECORD of Pu in Enewetak Soil by Alpha Particle Counting for Record, 27 Ott 76, Same Subject 1. Ref 1 reported interim results of a study to compare alpha particle count rates of Enewetak soil samples with their total specific alpha particle zctivity zs determined by radiochemi.stry and reported in lWO-140. A reasonably Good correlation was determined for 11 of 13 samples investigated. Since alpha particle count rates for the two “outliers” was reproducible, and their Pu content appeared too large, both samples were reanalyzed for Pu at USAF/MCL by radiochemistry. Results are as NUMBER PU CONC CONC (pCi/g) CONC (pCi/g) a ACTIVITY 2. Enclosure 1 tabulates the net alpha particle count rates and total specific activities for all 13 samples. The average count rate per unit specific activity was determined both as the ratio of the means, $1 , and the mean of the ratios, B*: A linear regression yielded the relationship: with a coefficient of determination, r2 = 0.9525. in enclosure 2 as a broken line. All data points withf.n cj.rcles, and the solid line is a plot of Y This curve is plotted are shown in enclosure 2 3. Alpha particle counting (without chemistry) continues to look suitable as a rapid method for estimatin~;the concentration of transuranics in Enewetak soil at concentration levels of interest to Cleanup. A possible explanation for the high Pu concentrations reported in lWO-140 for samples 5116 and 5196 is that (WOg) aliquots contained “hot particles” and the
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SUBJECT: Determination of Pu in Enewetak Soil by Alpha Particle Counting aliquots were not representative of the entire (~1000g) ball-milled sample. This explanation suggests that alpha particle counting (without chemistry) might also be used as a simple independent check of radiochemical analyses whenever small aliquots of large environmental samples are analyzed for transuranics. as Health Physicist
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Alpha Particle Counting of Enewetak Soil Samples NET a COUNT RATE TOTAL u SPECIFIC ACTIVITY
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