7.4.9 Ruby Background Island Ruby (Marshallese: Eleleron) is a small moderately vegetated islet, 1.5 hectares in area, lying between Pearl and Sally. This island was originally much larger and was connected to Sally by a causeway, but most of the island was destroyed by the George and Mohawk nuclear events which were conducted there. (See Section 7.5 for more information on Ruby and the changes it went through due to the testing operations.) Some debris remained on Ruby but was removed during the cleanup operation. This island ranks 2nd among the islands in the Atoll with 10,643 R/h total H+ 1 hour exposure rate, but most of the land mass receiving this exposure has been blasted or eroded away. There were no known or suspected burials of radioactive materials on Ruby. 1972 Survey Results Five locations were soil sampled during the 1972 survey and a few vegetation samples were also taken. There was only one profile sample and the other four locations had 0-15 em core, samples. The one profile showed a homogeneous distribution of low activities for 1 Cs, 905p and 239, 240p,,, Tables 7-1, 7-2 and 7-3 summarize the results of the 1972 sampling for the 0-15 em data for 137s, 90Sr, and 239,240py, respectively. Characterization Ruby was measured by the IMP at 9 locations with a 25 m spacing in March 1978. Four locations were soil sampled to determine a ratio of TRU to 241m with each location having two composites at each of three depths for a total of 24 samples (see Section 4.2.1 for details on surface sampling). A ratio of 6.42 + 0.39 was estimated for Ruby (see Tech Note 2.16). Figure 7-38 indicates both IMP and soil sample locations. Using the ratio and the 241Am IMP results, TRU values were calculated. Due to the small size of this island and few data points, no kriging estimates were made. All computed TRU values were below 10 pCi/g based on original data. (See Tech Note 23 for discussion of original versus final data.) After this initial characterization of Ruby, it was discovered that the detector used to measure Ruby experienced a loss in efficiency and the calculated 241 am IMP data were low. A correction factor was estimated and the data adjusted for the final characterization. (See Tech Note 5.2 for details on this problem and the determination of the correction factor.) Figure 7-39 shows the isopleth of TRU activity based on final data after the IMP data were ggrrected for the detector efficiency. Table 7-4 gives island means for computed TRU, 137Cs and Co activities for the final IMP data. Two locations were sampled to a depth of 80 em to verify that no subsurface pockets of contamination existed on Ruby. The subsurface samples were taken because the original island was the site of two ground zeros. One 80 cm data result did indicate an elevated TRU activity but it was below 160 pCi/g. Fission Product Sampling Three locations were sampled on Ruby for the Fission Product Data Base Program in support of the dose assessment (see Section 6.11). Soil from one of the three locations was analyzed for 9%sr. Tables 7-1, 7-2 and 7-3 summarize the 0-15 em data for 13% Gg, 90s- and 239,240 py. respectively. The island average transuranics value reported in the Certification is 8 pCi/gm for surface soil, and the transuranics classification is Residence. 248