canceling, it is assumed the results are correct to within ~20 percent. The geometries (or counts/beta) for Shelves 1 through 5 are given in Section A.2. Air-ionization rates 3 feet above an infinite uniformly contaminated plane, hereafter referred to as standard conditions (SC), are based on the curve shown in Figure B.6, which was originally obtained in another form in Reference 7. The particular form shown here, differing mainly in choice of parameters and units, has been published in Reference 45. Points computed in Ref- erence 46 and values extracted from Reference 47 are also shown for comparison. values are low, because air scattering is neglected. Thelatter The ionization rate (SC) produced by each fission-product nuclide as a function of time for 10‘ reference fissions/ft? (Reference 17), was computed on a line-by-line basis; the induced products appear in Table B.19 for 10‘ fissions/ft? and a product/fission ratio of 1, with lines grouped as described for the doghouse-counter-response calculations. The foregoing sections provide all of the background information necessary to obtain the objectives listed in the first paragraph of Section 3.4.1, with the exception of the actual radionuclide composition of the samples. The following sections deal with the available data and methods used to approximate the complete composition. 3.4.4 Observed Radionuclide Composition. Radiochemical R-values of fission products are given in Table 3.17 and observed actinide product/fission ratios appear in Table 3.18, the two tables summarizing most of the radiochemistry done by the Nuclear and Physical Chemistry, and Analytical and Standards Branches, NRDL (Reference 34). The radiochemical results in Reference 34 are expressed as device fractions, using fission yields estimated for the particular device types. These have been converted to R-values by use of the equation: FODg(x) FYp(x) RG (x) = FOD(O9) * FYq(x) Where R*}(x) is the R-value of nuclide x relative to Mo”?; FODg(x) and FYp(x) are respec- tively the device fraction and estimated yield of nuclide x reported in Reference 34, FY (x) is “the thermal yield of nuclide x, and FOD(99) is the device fraction by Mo*®. The thermal yields used in making this correction were taken from ORNL 1793 and are as follows: Zr®, 6.4 per- cent; Te!™, 4.4 percent; Sr®®, 4.8 percent; Sr®, 5.9 percent; Cs?87, 5.9 percent; and Ce, 6.1 percent. The yield of Mo’? was taken as 6.1 percent in all cases. The R-values for all cloudsample nuclides were obtained in that form directly from the authors of Reference 34. Published radiochemica] procedures were followed (References 48 through 54), except for modifications of the strontium procedure, and consisted of two Fe(OH), and BaCrO, scavenges and one extra Sr(NOQ), precipitation with the final mounting as SrCO,. Table 3.19 lists princi- pally product/fission ratios of induced activities other than actinides for cloud samples; sources are referenced in the table footnotes. Supplementary information on product/fission ratios in fallout and cloud samples was ob- tained from gamma-ray spectrometry (Tables B.20 and B.21) and appears in Table 3.20. 3.4.5 Fission-Product- Fractionation Corrections. Inspection of Tables 3.17 through 3.20, as well as the various doghouse-~counter and ion-chamber decay curves, led to the conclusion that the radionuclide compositions of Shots Flathead and Navajo could be treated as essentially unfractionated. It also appeared that Shots Zuni and Tewa, whose radionuclide compositions seemed to vary continuously from lagoon to cloud, and probably within the cloud, might be cov- ered by two compositions: one for the close-in lagoon area, and one for the more-distant ship and cloud samples. The various compositions are presented as developed, starting with the simplest. The general method and supporting data are given, followed by the results. Shots Flathead and Navajo. Where fission products are not fractionated, that is, where the observed R®%(x) values are reasonably close to 1 (possible large R-values among lowyield valley and right-wing mass numbersare ignored), gross fission-product properties may 58