Sensitivity Analysis of the Radial Distribution Model. Sensitivity to Carrier Material, Yield and Type of Fission

摘要

A method was previously developed for calculating the distribution of fission-product nuclides among fallout particles as a function of size. Calculations from this Particle Activity Module of radionuclide fractionation in land-surface nuclear bursts were tested for sensitivity to three kinds of input parameter variation: (1) variation in weapon yield, (2) variation in type of fission and (3) difference in solidification temperature of the carrier material (silicate soil or coral). During the calculations a fourth input parameter, particle-size distribution, was unchanged. The calculations show the model to be relatively insensitive to variation in weapon yield and type of fission. The calculations at a solidification temperature appropriate to coral (2887K) indicated that particles smaller than 47 microns in diameter contribute about 70% of the total exposure rate, while the calculations at the silicate soil solidification temperature (1673K) indicate about 60%. The proportions of the 1-hr exposure-rate contributed by volatile, mixed, and refractory fission-product chains are considerably different for the two solidification temperatures. The temperature sensitivity of the model should be investigated in more detail, since there is reason to believe that changes in fractionation behavior which are not apparent at 1 hour after burst might be important at later times. (Author)