RADIOCHEMICAL-DATA CORRELATIONS ON DEBRIS FROM SILICATE BURSTS GLENN R. CROCKER, FRANCIS K. KAWAHARA, and EDWARD C. FREILING U. S. Naval Radiological Defense Laboratory, San Francisco, California ABSTRACT Local-fallout samples collected in 1962 in the Johnie Boy, Small Boy, and Sedan shots were analyzed radiochemically for *Sr, *sr, *'y, zr, 9Mo, Ru, Ru, 7, pe, Mog Wicg MB, Mice Mice 2%Np and ?39pu. These results, as reported by the project officers, have been correlated by plotting the log of the ratio of equivalent fissions of each nuclide, i, to equivalent fissions of *Zr, Yr;95, against the log of the similar ratio for ™Sr and *°Zr, roy 9¢. The data werefitted to straight lines by linear regression; and slopes, intercepts, coefficients of correlation, and confidence limits were determined. The slope of such a line for a nuclide i is an indication of the degree of fractionation of the nuclide relative to the fractionation of *’Sr. For all cases observed in these Nevada shots, the same groupof nuclides (®Sr, °°sr, *ty, *Ru, Ru, MY, pe, B8Cg MOR, MICs Mice, and 78°Np) fractionated from *°Z7r. The nuclides Mo, '“4Ce, and ***Pu did not fractionate appreciably from ™Zr. For the Sedan shot the slope of the '’Cs plot is near 1.0, but, for the remaining fractionating nuclides, the slopes lie within a narrow intermediate range. For the Johnie Boy and Small Boy shots, for which the results are quite similar, these slopes show much wider variation. The results of the correlation have been compared with those from similar correlations for a coral-surface burst and some air bursts. Aside from the fact that °*Mo fractionated from *°Zr in the air bursts and that ?Np did not fractionate from *°Zr in the coral- surface burst, the results indicate that differences in the fractionation behavior of the nuclides are of degree rather than of kind. Correlation of radiochemical results with particle size indicates increasing degree of fractionation with increasing particle size. 72