SLIDE 12 Iodine activity on the surface. Based on archival soil measurements the iodine isotope activity per unit area of soil at the cessation of fallout at Rongelap was tabulated. It was assumed that iodine isotopes were enriched in the same amount as I, as indicated to us by archival soil results. The total radioiodine soil activity per unit area, based on archival soils from Rongelap, exceeded the measured total activity per unit area by a factor of ten! The total activity per unit area was based on four soil samples taken and measured for gross beta activity on March 8, 1954 (0C68). Conversion of the fodine surface activity (derived from archival soils) to exposure rate one meter above a plane source yields an estimated exposure rate 12 times greater than what was measured. Because of this disparity, the ggsumption could not be made that todine isotopes reflected the behavior of I in archival soils. The level of 1297 in archival soil may be real, an artifact of the neutron activation technique, or the residue from other weapons tests occurring near the §ime of soil collection. Comparison of Bikini Ash 129) to the hypothetical I leads one to believe that some enrichment of occurred but not to the extent indicated by our extrapolation of archival soil measurements. ACTIVITY PER UNIT AREA AT RONGELAP 0.6 DAYS POST DETONATION Bq m~* Archival Soils Nuclide tal 132! saa me ae I . Exposure Rate One Meter Above Plane of Activity Measured Total Exposure Rate 52X10) - 7.0X10 2.2% 10° 0.14 ° 2.5 7.4102 2.4 74X10 9.3X10 0.098 7.0 17