COMPARISONS OF IMP SCREENING AND LAB RESULTS DOE/ERSP TECH NOTE NO. 6.1 DATED: 9 September 1978 AUTHOR: J. Giacomini, DRI An in-the-field soil screening procedure has been developed whereby soil samples are counted using the in situ van (IMP). A physieal description is given by Burson in Tech Note 6.0, IMP Soil Sample Counting System. This tech note offers data comparing the field screening method to laboratory assay methods for identical samples. Table B-6-2 shows results for IMP screening and by radiochemistry and alpha spectroscopy. The mean ratio for IMP to gamma results is 1.05 with a standard deviation of 0.35. The mean ratio for the IMP to chemistry results is 1.20 with a standard deviation of 0.32. Table B-6-3 shows 2414m results for soil samples counted by the IMP and by laboratory gamma counting. The results shown are for soil samples collected from Sally. Figure B-6-2 is a plot of the data shown in Table B-6-3. The line shown is the simple linear regression line calculated from the data plotted. The regression line has a slope of 0.96 and an intercept of 0.53. The correlation coefficient is 0.94. The 95% confidence interval for both sets of data includes the ratio 1.0. Using the IMP as deseribed in Tech Note 6.0 is an acceptable method of in-the-field soil sample screening. It is not intended to be used as a replacement for laboratory soil sample counting or analysis by radiochemistry but does provide a method for rapid field screening of 241Am in soil samples. TABLE B-6-2. COMPARISON OF IMP SCREENING DATA WITH LAB CHEMISTRY RESULTS (pCi/g 241Am, BALLMILLED SAMPLES) STAKE LOCATION ~11,5-N-4.5 9.25-S-7.25 9.25-S-7.5 -14-N-6 DEPTH,cm 0 20 40 60 80 100 0 60 0 20 0 20 40 80 IMP 3 2 <1 <1 <1 <1 13 3.5 3 118 209 2.8 4.9 4.0 GAMMA 4.97 0.90 <MDA 0.10 <MDA 0.13 27.42 2.96 3.84 121.75 0.6 2.47 2.69 3,15 B-6-3 CHEM. 9-64 1.30 0.25 0.25 0.17 0.29 11.59 2.67 3.32 122.04 2.70 2.65 2.43 2.86 RATIO (IMP/CHEM) -89 1.54 1.12 1.31 -90 97 93 1.06 1.85 1.40