7.4.14 Wilma Background Island Wilma (Marshallese: Billae) is a small island in the east-northeastern part of the Atoll with an area of 6.4 hectares. The island is densely vegetated and was the site of several scientific stations used during the nuclear testing program. There appeared to be some soil disturbance as a result of debris removal, but all IMP measurements were made after debris removal. Wilma had no ground zero sites and ranks 21st among the islands in the Atoll with a 294 R/h totai H + 1 hour exposure rate. There are no known or suspected burials of radioactive material on this island. 1972 Survey Results During the 1972 survey, soil samples were collected at 23 locations and one vegetation sample was taken. Of the 23 samples, 19 were 0-15 cm core samples, two were 0-35 em profiles, and two were 0-65 em profiles. The profile results indicated the activities of 13 Cs, 90sr and 239,240 py to be declining steadily with increasing depth. Tables 7-1, 7-2 and 7-3 summarize the results for 137 og, 90sr and 239,240 py activities, respectively, for the 0-15 cm core samples. Characterization Wilma was measured with the IMP on a 50 m gridin March 1978. To determine a TRU to 241 am ratio, four locations were soil sampled with each location having two composites at each of three depths for a total of 24 samples (see Section 4.2.1 for more information on soil sampling). A ratio of 2.76 + 0.09 was estimated based on these results (see Tech Note 2.14). Both IMP and soil sample vo OO i“ © 00 ®@ Ne !) OO © LAGCON “— OO O sf BO NNpperoxiMaTe HIGH TIDE LINE, I972 / BL /® © = IMP LOCATION / OCEAN 52 C) s-\ & \ A = BENCHMARK PIRAI! C) ( nipe locations are shown in Figure 7-47. TRU values were calculated using the estimated ratio and the X = SOIL SAMPLE LOCATION ©)YY / WILMA - BILLAE " 50m FIGURE 7-47. COASTLINE AND DATA COLLECTION LOCATIONS FOR ISLAND WILMA 298