The ratio of nuclide activity to total activity was estimated from all of the activities listed in Table 13. The total activity in Bikini ash included the contribution of transuranics and activation products and was somewhat differ- ent in composition from hypothetical and undisturbed fission products. On day 0.5 at Rongelap, a total activity per unit mass of soil of 5.5 x 10° Bq gt (15 uCi g~1) was estimated from Bikini ash. A good portion of the activity was due to the decay of 239Np and 237y and other short-lived nuclides. The presence of short-lived activation and transuranic nuclides influenced the overall fallout decay exponent. A value for total activity per unit mass of soil of 1.6 x 10% Bq g™! (0.44 uci g@!) at 1.5 days at Utirik was estimated. The ratio of nuclide activity to total activity based on Bikini ash is tabulated in Table 7, column D. 7. Comparison of Archival Soil Measurements to Thermonuclear Fission Data and Bikini Ash Estimates. The archival soil results were compared using the ratios of nuclide activity to total activity (Table 7, columns B/E, D/E, and B/D). For !25gph the ratios were not similar; however, soil sample-size was small. For 1558u and 137¢., results were in accord at both Rongelap and Utirik. The archival soil results for 129t at Rongelap and Utirik were distinctly different from the hypothetical thermonuclear-fission results and Bikini Ash results. In order to estimate the significance of the wide differences for 1297 results, the standard deviations of the activity ratios were determined. The standard deviation of the archival soil best-fit value at 0.5 day (Table 7, column A) was gpproximated by linear regression methods (Be69). The archival soil result for 497 at Rongelap was 7.8 x 10> + 6.7 x 10°¢ Bq gt (2.1 x 1079 + 1.8 x 1072 pci gt) at the time of fallout cessation. The standard deviation of the four measurements of total activity per unit mass of soil on March 8, 1954, was 134% of the mean (0C68). The mean and standard deviation of the archival soil activity ratio (Table 7, colum B) was estimated to be 2.6 x 10719 + 2.35 x 1079. Thus it is concluded that a significant difference between this ratio and the other two cannot be determined due to the large standard deviation. Columns B/E and B/D are also uncertain for 1291. Errors in the thermonuclear fission product activity ratio for 1297 (Table 7, column E) were due to errors in independent yield data and half-life measurements and were estimated by Crocker to be on the order of 10% (Cr65). mean and standard deviation of this hypothetical ratio was estimated to be 3.5 The x 10712 + 5.0 x 10713, A wide divergence between the measured activity ratio and the hypothetical activity ratio was possible. It may have been due to chemical and physical phenomena experienced by nuclides in the 129 mass chain at different times postdetonation. Enrichment by a maximum factor of 100 has been noted occasionally (Fr6l). the 155gu and !37¢s archival soil activity ratios relative to the hypothetical ratio and the Bikini Ash ratio ranged between 0.87 and 1.4 for Rongelap soils and 0.33 and 0.45 for Utirik soils. These ratios were within acceptable limits of statistical uncertainty and are comparable. -17- The Bikini Ash activity