in cloud material: Na and K were found to undergo extensive fractiona- tion in JANGLE, 20/ 5.3.3 in The most important radionuclides produced by neutron reactions in the device components are p739 , 0237, and 0240, (9239 18 also important but is too short-lived to have been seen in our measurements). They were produced in sufficiently high yields to affect the gross decay rates of the residual contamination and to contribute significantly to the radiations from the contaminant, 5 e3edelL Results To illustrate the extent to which these radionuclides contribute, their counting rates measured at the same shelf geometry and corrected for chemical yield and decay are presented in Table 5.16. In order to allow comparisons of their acti levels with those of fission products, corrected counting rates for Mo”? at the same shelf geometry are also presented, Conversion of the above relative counting rates to relative numbers of atoms requires determination of counting efficienci These have been obtained for all of the above radionuclides except 7240, Consequently, there are presented in Table 5.17, for each sample, the number of atoms of Npe39 and 0237 uced relative to the number of fissions ocourring aa measured by Mo7’. 54 IN Radiochemical methods can provide an accurate determination of the fraction of the bomb included in fallout samples. The data required are the total number of fissions occurring in the detonation and the number of fissions giving the activity in the fallout sample. These determinations have been made bv radiochemical means, the first at Los Alamos Scientific Laboratory,2Yand the second here. 5 ehel Result