Radionuclide Fractionation in Bomb Debris

The composition of fractionated samples from high-yield surface bursts is correlated logarithmically. The slopes obtained for the various mass chains (except for molybdenum-99) are relatively insensitive to the environment and are empirically related to precursor volatility. Zirconium95, cerium-144, uranium- 237, and neptunium-239 do not fractionate grossly from one amother, nor does molybdenum-99 fractionate from these radionuclides when coral is in the environment; cesium-137 does not fractionate grossly from strontium-89. The fact that the slopes of the correlation curve for two radionuclides are identical within their respective mangins of error cannot be interpreted as meaning that no fractionation was observed. Small degrees of fractionation between similarly behaving radionuclides are best tested by plotting the ratio of their f values against the fractionation index. Even the data with the poorest fit fall wide of the correlation lines only by a factor of about 2. IN all cases except that of the deep-water surface burst, the cloud sample was found to be rich in strontium- 89. (auth)