VARIATIONS IN NATURAL ENVIRONMENTAL GAMMA RADIATION AND ITS EFFECT ON THE INTERPRETABILITY OF TLD MEASUREMENTS MADE NEAR NUCLEAR FACILITIES

摘要

Monthly measurements made with LiF (TLD-700) thermoluminescence dosimeters at several sites for two years form the basis of a study of the variations in natural environmental radiation both with location and with time. Various methods for estimating environ¬mental exposures in the absence of direct measurements are examined. They include the assumptions that natural environmental radiation does not vary with location and time and the use of a model based on the soil-water balance for estimating exposure variations with time at any particular location. Included is a discussion of the applicability of the various techniques for accurately subtracting background radiation from total exposure measurements for the purpose of isolating exposures attributable to the release of radioactivity from nuclear facilities. Examples are presented of TLD measurements made in the vicinity of nuclear power plants analyzed to isolate plume exposures. The results are compared with ionization chamber measurements of plume exposure and estimates made with models based on reactor effluents and meteorological conditions.