major stations constitutes an adjustment for relative platform bias, the question remains as to what percent of the total numberof fissions per unit area, which would have been deposited in the absence of the collector, were actually collected by it. This question is considered in detall in Section 4.3.2. 3.3.4 Chemical Composition and Surface Density. The total mass of the fallout collected per unit area at each of the major stations is summarized for all four shots in Table 3.16. Results are further divided into the amounts of coral and sea water making up the totals, on the assumption that all other components in the device complex contributed negligible mass. These values were obtained by conventional quantitative chemical analysis of one or more of the OCC tray collections from each station for calcium, sodium, chlorine, potassium, and magnesium (Ref- erences 35 through 38); in addition analyses were made for iron, copper and uranium (private communication from C.M. Callahan and J.R. Lai, NRDL). The basic ¢hemical results are presented in Tables B.16 and B.18. (Analyses were also attempted for aluminum and lead; possibly because of background screening, however, they were quite erratic and have not been included.) The chemical analysis was somewhat complicated by the presence in the collections of a rela- tively large amount of debris from the fiberglass honeycomb (or hexcell) inserts, which had to be cut to collector depth and continued to spall even after several removals of the excess material. It was necessary, therefore, to subtract the weight of the fiberglass present in the samples in order to arrive at their gross weights (Table B.18I). The weight of the fiberglass was determined in each case by dissolving the sample in hydrochloric acid to release the carbonate, fil- tering the resultant solution, and weighing the insoluble residue. In addition, the soluble portion of the resin binder was analyzed for the elements listed above and subtracted out as hexcell contribution to arrive at the gross amounts shown (References 39 and 40). Aliquots of the solution were then used for the subsequent analyses. It was also necessary to subtract the amount of mass accumulated as normal background. These values were obtained by weighing and analyzing samples from a number of OCC trays which were known to have collected no fallout, although exposed during the fallout period. Many of the trays from Shot Cherokee, as well as a numberof inactive trays from other shots, were used; and separate mean weights with standard deviations were computed for each of the elements under ocean and land collection conditions (Tables B.16 and B.18). After the net amount of each element due to fallout was determined, the amountsof original coral and sea water given in Table 3.16 could be readily computed with the aid of the source compositions shown in Table B.16. In most cases, coral was determined by calcium; however, where the sea water/coral ratio was high, as for the barge shots, the sea water contribution to the observed calcium was accounted for by successive approximation. Departure from rere the residual weights of the coral and sea water components shown in Table B.18 reflect combined errors in analyses and compositions. It should be noted that all + values given in these data represent only the standard deviation of the background collections, as propagated through the successive subtractions. In the case of Shot Zuni, two OCC trays from each platform were ‘analyzed several months apart, with considerable variation resulting. It is not known whether collection bias, aging, or inherent analytical variability is chiefly responsible for these discrepancies. The principal components of the device and its immediate surroundings, exclusive of the naturally occurring coral and sea water, are listed in Table B.17. The quantities of iron, copper and uranium in the net fallout are shown in Table B.18I to have come almost entirely from this source. Certain aliquots from the OCC trays used for radiochemical analysis were also ana- lyzed independently for these three elements (Table B.18I). These data, when combined with the tabulated device complex information, allow computation of fraction of device; the calculations have been carried out in Section 4.3.4 for uranium and iron and compared with those based on Mo”®, 3.4 RADIONUCLIDE COMPOSITION AND RADIATION CHARACTERISTICS 3.4.1 Approach. If the identity, decay scheme, and disintegration rate of every nuclide in 56