tion or by assumingthat all effects decay alike, consider the lagoon-area ionization curve for Shot Tewa (Figure 3.39) which indicates that the 1-hour dose rate may be obtained by multiply- ing the 24-hour value by 61.3. At‘? correction yields instead a factor of 45.4 (—26 percent error), and if the doghouse-decay curve is assumed proportional to the ionization-decay curve, a factor of 28.3 (—-54 percent) results. To correct any effect to another time it is important, therefore, to use a theoretical or observed decay rate for that particular effect. 4.3.4 Fraction of Device by Chemistry and Radiochemistry. The size of any sample may be expressed as somefraction of device. In principle, any device component whoseinitial weight is known may serve as a fraction indicator; and in the absence of fractionation and analytical errors, all indicators would yield the same fraction for a given sample. In practice, however, only one or two of the largest inert components will yield enough material in the usual fallout sample to allow reliable measurements. These measurements also require accurate knowledge of the amount and variability of background material present, and fractionation must not be introduced in the recovery of the sample from its collector. The net amounts of several elements collected have been given in Section 3.4.4, with an assessment of backgrounds and components of coral and sea water. The residuals of other ele- ments are considered to be due to the device, and may therefore be converted to fraction of device (using Table B.17) and compared directly with results obtained from Mo. This has been done for iron and uranium, with the results shown in Table 4.8. Fractions by copper proved inexplicably high (factors of 100 to 1,000 or more), as did a few unreported analyses for lead; these results have been omitted. The iron and uranium values for the largest samples are seen to compare fairly well with Mo™®, while the smaller samples tend to yield erratic and unreliable results. 4.3.5 Total Dose by Dosimeter and Time-Intensity Recorder. Standard film-pack dosimeters, prepared and distributed in the field by the U.S. Army Signal Engineering Laboratories, Project 2.1, were placed af each major and minor sampling array for all shots. Following sample recovery, the film packs were returned to this project for processing and interpretation as describ- ed in Reference 76; the results appear in Table 4.9. The geometries to which the dosimeters were exposed were always complicated and, ina few instances, varied between shots. In the case of the ship arrays, they were located on top of the TIR domein the standard platform. On How-F and YFNB 29, Shot Zuni, they were taped to an OCC support ~ 2 feet above the deck of the platform before the recovery procedure became established. All other major array film packs were taped to the RA mast or ladder stanchion ~2.5 feet above the rim of the platform to facilitate their recovery under high-dose-rate conditions. Minor array dosimeters were located on the exterior surface of the shielding cone ~ 4.5 feet above the base in the case of the rafts and islands, and ~5 feet above the deck on the masts of all skiffs except Skiffs BB and DD where they were located ~ 10 feet above the deck on the mast for Shot Zuni; subsequently the masts were shortened for operational reasons. Where possible, the dose recorded by the film pack is compared with the integrated TIR Teadings (Table B.1) for the period between the time of fallout arrival at the station and the time when the film pack was recovered; the results are shown in Table 4.9. It has already been indicated (Section 3.4.6) that the TIR records only a portion of the total dose ina given radiation field because of its construction features and response characteristics. This is borne out by Table 4.10, which summarizes the percentages of the film dose represented in each case by the TR dose. It is interesting to observethat for the ships, where the geometry was essentially constant, this percentage remains much the samefor all shots except Navajo, where it is consistently low. The same appears to be generally true for the barge platforms, although the results are Much more difficult to evaluate. A possible explanation maylie in the energy-response curves of the TIR and film dosimeter, because Navajo fallout at early times contained Mn** and Na™ —both of which emit hard gamma rays— while these wereoflittle importance or absent in the Other shots. 121