samples), the surface ‘density ranged from 4 to 7 ple at 16). mg/so ft (with - On Shot 3, the surface density of a ores from300)to 7000 mg/sq ft (with one sample at 12,000). The surface density of equivalent sea water on Shot 2 ranged from 2 to 11 ml/sq ft. The samples collected wers both dry and wet, For those containing liquid, the concentration analysas gave too low values to indicate a pure sea water splash-1a. Some rain was experienced during recovery of these samples. ‘ence, Shot 2 fallout was probably essentially a dry material when it arrived at the collectors. On Shot 3, the surface density of sea water ranged from 2 to 30 ml/sq ft. The island station and 3-bottle sampler values were near the lower end of the ranges the total collector on Coca Head gave a mid-range value; the total collectors on the lagoon rafts and buoys generally gave values at the high end of the range as shown by the split distribution plot. No definite information is available as to when the sample bottles were last checked for splash-in prior to shot time. It seems likely, however, from the analyses alone that the higher distribution was due to splash-in and that the 2 to 15 ml/sq ft surface density is the more reliable distribu- tion. On Shot 4, the single sample gave a value of 11 ml/sq ft for the equivalent surface density of the sea water component, The surface density of the device is given for Fe in terms of fraction of the device which fell on each square foot range from about 1 x 10722 to 10 x 10722 on Shot 1 for the lagoon station samples. & mid-range fractional density of 4.3 x 10°12 per sq ft would give (as a minimum) a coverage of about 8000 sq mi for a 100 per cent fallout. On Shot 2, the fractional surface density for the device ranged from about 3 x 10712 to 20 x 10722 per sq ft. On Shot 3, the fractional surface density ranged from about 100 x 10°12 to 300 x 10712 for the majority of samples. A mid-range fractional density of 230 x lot per sq ft would give a coverage of about 1450 sq mi for a 190 per cent fallout. The areas for a 100 per cent fallout are given only for a qualitative check on the analytical data and do not indicate the actual coverage such as do the fallout distributions as given in the CASTLE report of Project 2.5a. If it would have been possible to analyze the fallout samples at more sta- tions, fallout contours of surface density of coral, sea water, and device products could have been determined for comparison with the dosage contours. On Shot 4, the one value at 1.5 x 10~12 per sq ft was about a factor of 3 less than the mid-range value for Shot 1 and roughly a factor of 5 or 6 less than that for Shot 2. A comparison of an estimated radiation field to the surface density of each component is made in Table 3.21, with the corresponding distributions given by Figs. 3.15 through 3.17. The total gamma counts for each fallout collector bottle (taken in the same geomatry) were corrected back to 1 hr from a calculated beta decay scheme (see Chapter 5). For Shot 1, the estimated radiation field reeding at 1 hr given by Project 2.5a was used. On Shots 2 and 4, preliminary estimates of the field were made using uncorrected data taken from recorded data on a 50 x 50 ft section of flight deck of the YAG 40 at as early a time as possible (5 te 16 hr). These readings were compared to the total gamma count in the Project 2.5a total collectors. On Shot 2, the ratio of r/hr to c/m ranged from 0.026 x 1077 to 0.051 x 10°? while on Shot 4, the ratio 75