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• - <br />To assess exposures to members of the public, DOE evaluated a scenario in which an <br />individual camps on a mine-tack waste pile for 24 hoots a day over a 14-day period. This <br />time period was used at the suggestion of EPA (Iammering 1994). Lease tract 13 was <br />selected for assessment because it is the most accessible to the public and because of its close <br />proximity to State Highway 141 and the historical community of Slick Rock. Additionally, <br />this area is populaz with visitors for viewing desert bighorn sheep and for rafting the Dolores <br />River. The exposure value resulting from this scenario on lease tract 13 is considered <br />representative of the amount of radiation an individual could be exposed to at any other lease <br />tract because of the physical similarities of all the mine sites and mine-rock waste piles. <br />The TEDE resulting from exposure was estimated with RESRAD software (Argonne <br />National L,abotatory 1993), which is a software package that performs random dose <br />calculations using pathway analysis. The calculated TEUE was 79 mrem/yr, this value does <br />not exceed the NRC standard of 100 mrem/yr. The average value of 0.04 percent U~08, <br />derived from historic data collected on lease tract 13, was used in the random dose <br />calculations. Several assumptions also were used in these calculations:, natural uranium was <br />assumed to be 99.28 percent uranium-238; the concentration of uranium-235 was assumed <br />to be 5 percent of the uranium-238 concentration (by activity); and uranium-235 and <br />uranium-238 were assumed to be in equilibrium with their decay products. The exposure <br />pathways analyzed included external exposur+t:.to gars-tnat~4liagQtt;,,inhalation of contaminated <br />dust and radon (and radon decay products}, and ingestion of cdtit"aetliia~ed"sot`t.'{"Y'tie~most <br />significant exposure pathway was external exposure from gamma radiation emitted from the <br />mine-tack waste pile, which caused 90 percent of the TEDE. <br />4.17.2 Vonradiological Hazards <br />Nontadiological hazards at the lease tracts that could pose a threat to human health include <br />unprotected mine openings such as adits. shafts. or inclines/declines. Currently, the lease <br />tracts posing the greatest risk to members of the public from the presence of physical hazards <br />are lease tracts 5. 6. 7, 9, 21, and 22A in the Paradox Valley area: lease tracts 11. 13. 13A. <br />14, and 15 in [he Slick Rock area: and lease tracts 18, 19, and 25 in the Uravan area. <br />UL\iP EA DOE Grind .lunctiuu Prgjects Ulrcr <br />P~~r 50 Arav 19, 199 <br />