The reason behind this unusual discrepancy was because detector SN:496, used to measure Lucy, had been mistakenly operated at a bias of -2000v rather than -3000v. An experiment was conducted on Sally to determine a factor to apply to the IMP data collected when the detector was operated at the lower voltage. (See Tech Note 5.0 for details on this experiment.) The decision was made in March 1978 to remeasure Lucy with the IMP on the same 50 m grid to verify the correction factor computed from Sally data. The same detector was used to remeasure the island and was operated at the correct voltage. These new data indicated that the correction factor applied to the original data was appropriate. : Using the corrected IMP data and the estimated ratio, TRU numbers were calculated based on original data. (See Tech Note 23 for discussion on original versus final data). Estimates of the 0.5 s upper bounds on the 0.25 hectare averages were made using the kriging technique, where s is the standard deviation of the kriging error (see Section 5.1). removal Lucy met condition B without any soil An additional problem in efficiency with detector 5N:496 was discovered shortly after Lucy was remeasured. Because the agreement between IMP measurements and the soil sample results was never as good as other islands, more IMP measurements (with detector SN:386) and soil samples were collected in March 1979. Only six locations on the initial 50 m grid were remeasured by the IMP because of a higher priority mission, but seven locations were soil sampled, where five of the locations were the original sites and the other two were new locations. The six IMP spectra showed no significant difference when compared to the corrected initial data. The soil sample results also confirmed the initial data were acceptable after they were corrected for the low voltage problem. Isopleths of surface TRU activity based on final data are shown in Figure 7-28. Table 7-4 gives the island averages for computed TRU, !37Cs and 89Co activities from IMP measurements. Fission Product Sampling Soil samples were collected on the 50 m grid already established in support of the dose assessment (see Section 6.11). Soil from eight of the 22 sampling locations was analyzed for Osr, Tables 7-1, 7-2 and 7-3 summarize the results for 0-15 em data for 13%Csg, 90sr and estimated 239,240py results, respectively. The island average transuranics value reported in the Certification is 35 pCi/gm for surface soil, and the transuranics classification is Agricultural. we we wa we a. ta £4 ‘ | N APPROXIMATE HIGH TIDE J Pwt 19°72 LUCY — KIDRINEN “50m FIGURE 7-28. ISOPLETHS ON FINAL ESTIMATED SURFACE TRU ACTIVITY IN pCi/g FOR ISLAND LUCY 236