Instruction from Las Vegas indicated the need to incorporate 238py into the ratio computations. This was done in the same manner as described above with the results being a total Pu/24lam ratio of 5.63. The new ratio, computed several ways, still appears to be acceptable for application to the entire island. "A" Samples Ratio No. 1 3 5 7 9 "B" Samples Ratio Ratio No. Ratio 1.877 3.451 5.591 5.536 9.228 2 4 6 8 10 1.871 5.319 5.392 5.352 8.060 Set or Subset "A" Samples "B" Samples Weighted Mean Simple 5.70 3.90 5.13 5.19 1-8 4.56 4.29 3-8 3-10 5,16 6.22 5.16 5.99 Nos. 1-10 5.63 5.16 Since it appears likely that more surface samples will be analyzed, and the resulting ratios used in final computations, the decision was made to proceed using a conservative value. ratio used to compute the second estimates was 6.0. Therefore, the If, in fact, different ratios are used on different parts of the island, the expectation is that the final distribution map would show lower values than are currently estimated for a significant portion of the island. Determination of an error term to associate with the mean ratio of 238,239,240py to 24lam is accomplished by computing the low-to-high range in ratio for each sample, then take the square root of the sum of the square of one-half the range for each sample, all divided by the number of samples (prior to taking the square root). The Pearl data has a weighted mean ratio and error term of 5.66 + .598. When the 238py is excluded from the data the weighted mean and error term is 3.825 + .495. 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-A DATED: 13 February 1978 AUTHORS: M. Barnes, DRI J. Giacomini, DRI A re-examination of all the existing soil data on ratios of total transuranics (238,289,240py ond 241 4m) to americium on Pearl indicated the existence of multiple distinct underlying populations. The ratios of total transuranies to 2414m at each soil sample location were plotted against distance from Inca ground zero (GZ) (Figure B-2-1). 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 B-2-2