US EPA

1422686 

Journal Article 

A method for determining relative amounts of combined and uncombined radon daughter activity in underground uranium mines 

Craft, BF; Oser, JL; Norris, FW 

1966 

Yes 

American Industrial Hygiene Association Journal
ISSN: 0002-8894 

NIOSH/00073555 

27 

2 

154-159 

English 

5953999 

10.1080/00028896609342809 

A method is described and tested for determining relative amounts of combined and uncombined radon daughter activity in underground uranium mines. It is based on the different diffusion coefficients of atomic size radon daughter products compared with those combined with particulates and operates by means of a diffusion tube that separates out a calculable fraction of the atomic-size daughter products and permits larger particulates to pass through the tube. A table summarizes the field studies in several underground uranium mines in southern Utah and Colorado. The amount of uncombined radon daughter activity ranges from almost zero up to 73 percent. This wide ranges indicates that it would be impossible to select any particular fraction of uncombined atoms as representative of actual mine conditions. Factors affecting the percentage of radon daughter atoms existing in the uncombined state are the atmospheric concentration of particulates, the amount of water vapor in the air, and the rate of air change in the area. It appeared that in areas where diesel smoke was present the fraction of uncombined daughters was low. It is stressed that if there is a difference between the combined or uncombined state as far as effective radiation dose is concerned, then this method of distinguishing between the two states would be critical in estimating effective exposure. 

DCN-178626; NIOSH Author; Analytical methods; Measurement methods; Radon daughters; Separation; Atomic particles; Radioactive products; Ionizing radiation; Radioactive materials; Radiation dosage; Radiation dosimetry; Radiation environment; Uranium miners