Evaluation of Atmospheric Radon in the Vicinity of Uranium Mill Tailings

Abstract

A field study is currently being concluded at Grand Junction and Durango, Colorado, and at Monticello and Salt Lake City, Utah, to evaluate the public health aspects of atmospheric 222Rn in the vicinity of uranium tailings piles. Air is collected continuously for 48 hr periods from each station in order to average out diurnal fluctuations. The integrated sample is then analyzed for 222Rn. A total of 57 stations is in operation. Each station is re-sampled every three weeks for one calendar year to include seasonal fluctuations and to permit a more realistic estimate of the yearly dose to people in the immediate vicinity. This paper presents data and conclusions from the 1 yr study. Of the 13 stations directly over tailings, average radon concentrations ranged from 3.5 pCi/l. to 16 pCi/l. Of the 44 stations not over tailings, only two averaged greater than 1 pCi/l. The results indicate negligible radiation exposure of the surrounding population from this source.

Scientific Basis for Risk Assessment and Management of Uranium Mill Tailings

“…The flux is highly variable in space and time: in space because of differences in 226Ra concentrations and porosity and permeability over very short distances, in time because of continually varying meteorological conditions and the degree of water saturation. Furthermore, it is difficult to make an accurate measurement of this flux-even at a specific time on a specific small area-without great care and special equipment (Shearer and Sill, 1969).…”

“…Despite the measurement problems, several studies (Kovach, 1945;Kraner et al 1964;Shearer and Sill, 1969;Clements and Wilkening, 1974) have examined the fluctuations in radon flux and radon concentration in air at a given location produced by changes in atmospheric factors. These studies show a substantial, but far from perfect, correlation between changes in atmospheric pressure and radon flux (Figure 2-3).…”

Radon and radon-daughter concentrations in air in the vicinity of the Anaconda Uranium Mill

“…Shearer and Sill (1969) measured background radon concentrations at selected mills and reported concentrations of 380 pCi/m^ for Vitro, 800 pCi/m^ for Grand Junction, 510 pCi/m^ for Durango, and 340 pCi/m^ for Monticello. Radon concentration at about 0.5 km from the Grand Junction tailings is between 780 and 1100 pCi/m^, decreasing to about 800 pCi/m^ at 1.5 km (Shearer and Sill 1969). At Durango, concentration of radon in air is about 500 pCi/m^ at 0.5 km and remains nearly the same to 4 km, but the concentration on the tailings is 12 000 to 19 000 pCi/m^.…”

“…Concentration of radon in the vicinity of inactive tailings has been reported (Shearer and Sill 1969, Snelling 1971, Schiager 1974, but concentration of radon and working level in the vicinity of an active mill has not been reported. The purpose of this study was to obtain long-term experimental data for the prediction of radiological impacts of uranium-milling operations.…”

Environmental Radiation and the Lung

“…The actinium series and other primordial radioisotopes in the earth's crust contribute very little to man's radiation dose (4)(5)(6)(7)(8)(9). The isotope 40K contributes about 17 mrem/yr of the 25 mrem/yr average internal whole body dose (3b).…”