Forecasting radiation rates and exposure from multi-aged fallout.

A graphical method for forecasting radiation exposure rates from multi-aged fallout is extended to include a nomogram method. A simple method for forecasting accumulated radiation exposure is also presented. It is shown mathematically that these methods can provide estimates of radiation exposure rates or cumulative exposures for intervals of a few days to a few weeks in the future to within +/- 30% from assumed actual radiation exposure rates or accumulated exposures for fallout that decays according to t-n, where n is any number from 0.8 to 1.6. Because of the self-adjusting feature of the method which results in an estimated effective age for the fallout, it is not necessary to attempt to subtract contributions from separate fallouts with different ages. The method can be applied to composite fallout without knowledge of the previous history of the various-aged contributions.