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High surface soil concentrations of 226Ra and high above-ground measurements of gamma-ray intensity in the vicinity of the inactive uranium-mill tailings at Mexican Hat show both wind and water erosion of the tailings. The former mill area, occupied by a trade school at the time of this survey, shows a comparatively high level of contamination, probably from unprocessed ore on the surface of the ore storage area near the location of the former mill buildings. However, the estimated health effect of exposure to gamma rays during a 2000-hr work year in the area represents an increase of 0.1% in the risk of death from cancer. Exposure of less than 600 persons within 1.6 km of the tailings to radon daughters results in an estimated 0.2%/year increase in risk of lung cancer.

It appears that nothing has been done to implement the recommendation of an earlier (1968) survey that tailings at this site be stabilized or that access be restricted with periodic monitoring to assure that population exposures are acceptably low. Data provided in this report and in an engineering assessment report by Ford, Bacon and Davis Utah Inc. will provide guidance for remedial action if that should be undertaken.


ORNL-5448 Dis. Category UC-41 Contract No. W-7405-eng-26 Health and Safety Research Division