ADDENDUM TO TECH NOTE 2.0: DETERMINATION OF THE RATIO OF TOTAL TRANSURANICS TO AMERICIUM IN SOIL ON ISLAND PEARL DOE/ERSP TECH NOTE NO,2.0-B* DATED: 15 March 1978 AUTHOR: M. Barnes, DRI A re-examination of all the existing soil data on ratios of total transuranics (238,239,240py and 241 4m) to americium on Pearl indicated the existence of multiple distinct underlying populations. The ratios of 239, 240py to 24l4m at each soil sample location were plotted against distance from Inea ground zero (GZ) (Figure B-2-2). Three distinct clusters of ratios were apparent: Cluster 1, containing samples within 150 meters of Inca GZ; Cluster 2, containing samples further than 150 meters but less than 350 meters from Inca GZ; and Cluster 3, containing samples more than 350 meters from Inca GZ. Simple means and standard deviations of the ratios in each cluster follow. The three means were compared using t-tests, and found to be statistically different at the 95% significance level. Cluster 1 2 3 Mean Ratio Standard Deviation 6.63 5,28 2.90 1.79 1.72 1.07 These results were used to draw boundaries around relatively homogeneous populations of ratios. Within each area so determined, the simple mean and standard deviation of the ratios of total transuranics to americium were calculated,** and those values used to compute total transuranics at each sample point in that area. Table B-2-1 shows the actual total transuranics to americium ratios at each soil sample location, and the mean and standard deviation for each area. The computed total transuranics values were used to derive estimates and upper bounds of quarter hectare and half hectare average concentrations. *This Tech Note supersedes Tech Note 2.0-A which is cancelled. **This method of estimating the ratio and error was later replaced by a method based on more accurate assumptions as described in Tech Note 2.2-A. B-2-4