Radon-222, from uranium mining

Bigu J, Grenier NK, Dave TP, et al. 1984. Study of radon gas concentration surface radon flux and other radiation variables from uranium mine tailings areas. Uranium 1 257-277. 

Austin, S.R., 1975. A laboratory study of radon emanation from domestic uranium ores. Radon in uranium mining, IAEA Vienna, PL-565/8, pp. 151-160. 

Barnes, I., Platfker, G., White, D. and Armstrong, A.K., 1980. Potential natural gas in the Gulf of Alaska indicated by calcite depleted in carbon-13. In W.L. Coonrad (cd.). The United States Geological Survey in Alaska - accomplishments during 1980. US Gcol. Survey, Circular 844, pp. 143-146.Barretto, P.M.C., 1975. Radon-222 emanation characteristics of rocks and minerals. Reprint from "Radon in Uranium Mining", IAEA, Vienna, pp. 129-150. 

In some instances, the source of radon is in wastes from uranium mining or phosphate production. In most cases, it is emitted by the radioactive decay of present in small amounts in rocks and soils. Because radon is a gas, it readily passes through air passages in the body and is breathed in and out. The product formed when a Rn atom gives up an a particle is the isotope polonium-218, which also emits a particles. Unlike radon, polonium is a solid. Health hazards posed by radon seem to be from Po and other radioactive decay products becoming attached to dust particles in the air and then being breathed into the lungs. 

Care must be taken in handling radon, as with other radioactive materials. The main hazard is from inhalation of the element and its solid daughters which are collected on dust in the air. Good ventilation should be provided where radium, thorium, or actinium is stored to prevent build-up of the element. Radon build-up is a health consideration in uranium mines. Recently radon build-up in homes has been a concern. Many deaths from lung cancer are caused by radon exposure. In the U.S. it is recommended that remedial action be taken if the air in homes exceeds 4 pCi/1. 

The presence of radiation in the workplace - which is an inevitable consequence of the radioactivity of uranium - requires that additional safety precautions be taken over and above those observed in other similar workplaces. There are generally three sources from which radiation exposure may occur (i) radiation emitted from uranium ore in-situ and/or during handling (ii) airborne radiation resulting from the decay of radon gas released from the ore and uranium dust and (iii) contamination by ore dust or concentrate. Radiation levels around uranium mining and milling facilities are quite low - for the most part only a few times the natural background levels - and they decrease rapidly as the distance from... 

This concentration is equivalent to a partial pressure of radon of 6.6x10 atmospheres. Yet this value is an elevated radon concentration. If all of the decay products formed by the decay of the radon remain in the air, then there would also be 10 pCi/1 of Po-218, Pb-214, etc. Such a mixture would be said to be in secular equilibrium. From the monitoring of uranium mines, an equilibrium mixture of these decay products at 100 pCi/1 is called a working level (WL). Thus, a 10 pCi/1 equilibrium mixture represents 0.1 working level. 

This paper deals mainly with the condensation of trace concentrations of radioactive vapor onto spherical particles of a substrate. For this situation the relation between the engineering approach, the molecular approach, and the fluid-dynamic approach are illustrated for several different cases of rate limitation. From these considerations criteria are derived for the use of basic physical and chemical parameters to predict the rate-controlling step or steps. Finally, the effect of changing temperature is considered and the groundwork is thereby laid for a kinetic approach to predicting fallout formation. The relation of these approaches to the escape of fission products from reactor fuel and to the deposition of radon and thoron daughters on dust particles in a uranium mine is indicated. 

The first surveys of radon in US (Colorado) uranium mines were made in 1952, when the raised incidence of lung cancer in miners first became apparent (United States Public Health Service, 1957). The level was highly variable, with medians for each mine varying from 7 x 102 to 3 x 105 Bq m-3. The median of the medians was 4 x 104 Bq m-3,1000 times higher than the median concentration in houses (Table 1.4). Subsequently, ventilation was improved and other measures were taken, for example disused parts of mines were sealed off. The median of medians was reduced to 1 x 104 Bq m-3 in 1956 and to 4 x 103 Bq m-3 in 1966. In a survey of six mines in New Mexico in 1970, George Hinchliffe (1972) found a median radon concentration of 7 x 103 Bq m-3. 

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