Exposure to local fallout, which has the greatest potential for producing human casualties, is very sensitive to assumptions about height of burst, winds, time of exposure, protection factor, and other variables. The total amount of gamma-ray radioactivity dispersed in a nuclear exchange is dominated by the weapon fission products whose production is proportional to the total fission yield of the exchange. Potential internal doses from ingestion and inhalation of gamma and beta emitters are estimated in only an approximate manner, as these are much more difficult to quantify. Contributions from external beta emitters are not estimated because of the limited penetration ability of beta radiation, but there is the possibility that in areas of local fallout, beta radiation can have a significant impact on certain biota directly exposed to the emitters by surface deposition (Svirezhev, 1985). Mainly the dose from gamma-ray emitters external to the body is considered. Global fallout will be further subdivided into an intermediate time scale, sometimes called tropospheric, of 1 to 30 days, and a long-term (beyond 30 days) stratospheric component.
The contributions from local (first 24 hours) and more widely distributed, or global fallout, will be considered separately. Prompt initial ionizing radiation within the first minute after the explosion is not considered here, because the physical range for biological damage from this source for large-yield weapons is generally smaller than the ranges for blast and thermal effects. Our focus is on the areas outside the zone of the initial blast and fires.
In this paper the potential doses associated with the radionuclides created by nuclear explosions are assessed.
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