Sampling of Technetium-99 in Vegetation and Soils in the Vicinity of Operating Gaseous Facilities. Environmental Sciences Division Publication No. 1550

摘要

Technetium-99 was measured in vegetation and soils collected near three operating gaseous diffusion facilities to obtain estimates of the soil-to-vegetation concentration factor. Analyses were performed primarily using radiochemical separations and low-level beta counting techniques with selected samples checked by isotope dilution mass spectroscopy. The concentration factor pooled from all three facilities appeared to be lognormally distributed with a geometric mean of 9.5 and a geometric standard deviation of 2.4. These values are comparable to calculated equilibrium concentration factors derived from other field experiments in which concentrations in soil and vegetation were observed to decrease with time subsequent to a single application of/sup 95m/TcO sub 4- . These field values are one to two orders of magnitude less than concentration factors derived from laboratory experiments using potted plants. It is suggested that the radiologic significance of exp 99 Tc in terrestrial food chains of importance to humans may be substantially lower than indicated by the simple difference between laboratory and field concentration factors if the time dependence of technetium activity in vegetation and soil is taken into consideration in radiological assessment models. (ERA citation 05:038713)