measurements and the expected beta activity data given in Table 1 represented differences between fractionated and unfractionated fallout. | As previously implied, the term fractionation indicated alterations of nuclide composition in fallout debris. The ratio of two nuclides in fallout was often used to describe fractionation quantitatively (Fr61). nominator of the ratio was taken to be the activity of ZrNb-95 (Fr61). The de- To quan- tify fractionation between two nuclides the beta activity ratios were compared. The term "degree of fractionation" represented the range of variability of the nuclide ratio. The term "extent of fractionation" represented the portion of the total nuclide produced which departed from the unfractionated ratio. A review of the data in Table 1 indicated the nuclides’ Te-132, I-132, I-131, Ce-141, RuRh-106, CePr~144 measured activity ratios (ratioed to measured ZrNb-95 beta activity) did not differ by a factor greater than about 1.5 from the unfractionated ratios. The nuclides BaLa~140, Nd-147, Y-91, SrY- 90, Ru-103 and Pr-143 fractionated by about a factor of 2 relative to the unfractionated ratios and the nuclides Sr-89 and Te-129m-Te-129 fractionated by about a factor of 3 relative to the unfractionated ratios. The nuclides Y-91, RuRh-106, Te-129m-Te-129, Te-132, I-132, CePr-144, Pr~-143 and Nd-147 were in greater abundance relative to unfractionated debris. The other nuclides were in less abundance. Freiling (Fr61) indicated that the degree of fractionation from a surface burst could be significant. The extent of the fractionation throughout the debris was another variable he observed to be significant. Freiling emphasized the high degree of fractionation between nuclides classified as volatile and refractory for coral atoll surface bursts. with much caution were made. Generalizations to be used Freiling, indicated that fractionation in general