REP15563

• Permit No: M1981021
• IBM Index Class Name: Report
• Doc Date: 9/1/1995
• Doc Name: MEMO REPORTS CONCERNING US DOE ADMINISTRATION OF URANIUM LEASE TRACTS IN SOUTHWESTERN COLO SOUTH
• From: MICHELLE REHMANN
• To: JIM DILLIE
• Media Type: D
• Archive: No

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4.17 Human ~iealth~
The mine sites on each o1' the lease tracts currently are considered inactive: however, both
rddiological and nonradiological physical hazards that could pose a threat to human health
exist on the lease tracts.
4.17.1 Radiological Hazards
Long-term exposure to ionizing radiation has been shown to cause a statistical increase in the
occurrence of cancer in humans (International Commission on Radiation Protection 1990).
Mine sites on the DOE lease [[acts comprise rocks and soils that contain narurally occurring
radioactive material (NORIvT); the majority of NORM is derived from the uranium-238 and
uranium-235 decay chains. One of the products in these decay chains is radium-226, which
is the principal radionuclide of concern for characterizing the redistribution of radioactivity in
the environment.
Background levels of radium-226 are normally present in soil in trace concentrations of about
I picocutic per gram (pCi,rg); however, background concentrations within ore-bearing
formations may be as high as hundreds of tfiousands of pieociiries per gram. Background
concentrations of radium-726 in mine-rock waste piles average 23.7 pCi/g (EPA 1991). The
primary radioactive sources on the DOE lease tracts are mine-rock waste piles, mine portals.
ore-bearing outcrops (Salt Wash Member of the Morrison Formation), and airborne
particulates derived from these sources. In underground mines, the primary radium-226
source is the ore-bearing Salt Wash Member.
The amount of radiation that is received by mine workers and members of the public is
directly related [o the amount of time they spend on or near the radioactive sources and to
the level of radioactivity inherent to the sources. At the present time, mine workers typically
visit the lease tracts for approximately 3 hours each month of the year, or for a total of
36 hours per year. Because most of the lease tracts are readily accessible by public roads
and are not secured by fern:es or locked gates. members of the public may spend more or
less time on the lease tract'. than the mine worker. Although members of the public are not
permitted [o permanently or temporarily reside on the lease tracts, some visitors may camp
for 1 or more days. Other activities that bring public visitors to the lease tracts include
hunting. hiking, and mountain biking. In general. a public visitor would not spend more
than 2 weeks (336 hours) per year on the lease tracts.
An individual may be exposed to radiation on the lease tracts through three primary
pathways: (1) external exposure to gamma radiation, (2) inhalation and ingestion of
resuspended radioactive particulates. and (3) inhalation of radon and radon daughter
products. These exposure pathways are analyzed to determine health effects on mine
workers and members of the public. Presently, the leaseholders ensure that worker and
public exposures do not exceed MSHA, NRC, and EPA regulations (see discussion in
Section 3.2 for exposure thresholds).
DOE Crmd Junction Projecu Onke UL1.IP EA
"{ ntny r9, 1995 Page 49