Design of UMTRA covers to mitigate the effect of frost penetration
The Uranium Mill Tailings Remedial Action (UMTRA) Project, contracted by the US Department of Energy (DOE), requires construction of disposal cells for residual radioactive materials from abandoned uranium mill tailings. A disposal cell consists of contaminated material placed within a stabilized embankment with a top cover. The embankment and cover should be effective for up to 1000 years, to the extent reasonably achievable, and in any case for at least 200 years. The embankment cover usually consists of a radon/infiltration barrier, a frost barrier and erosion protection layer consisting of bedding and riprap layers. The radon/infiltration barrier and frost barrier are two important elements of the cover systems. A radon/infiltration barrier is designed to reduce the radon emissions from the contaminated materials and to limit the surface water infiltration into the contaminated material. However, a radon/infiltration barrier has to be protected from repeated freeze-thaw cycles to prevent an increase in permeability. Frost penetration depth is site specific and depends on local climatic conditions and soil properties of the cover system. However, placing a frost barrier is not only very costly but also reduces the disposal capacity of the embankment. Recent laboratory test results indicate that freeze-thaw cycles do not significantly effect the permeability of compacted sand-bentonite mixtures. Therefore, radon/infiltration barriers using sand-bentonite mixtures may not require frost barriers for protection against the effects of freeze-thaw. In this paper the design of UMTRA covers is briefly explained; the criteria to determine a 200 year freeze event, and the frost penetration depth are discussed. The results of freeze-thaw permeability tests on compacted clay and sand-bentonite mixtures are also presented.
- Research Organization:
- Morrison-Knudsen Corp., Inc., Boise, ID (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-91AL62350
- OSTI ID:
- 10134889
- Report Number(s):
- CONF-940225-79; ON: DE94008604; BR: EW2010102/EX2040010
- Resource Relation:
- Conference: Waste management `94: working towards a cleaner environment,Tucson, AZ (United States),27 Feb - 3 Mar 1994; Other Information: PBD: [1994]
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
54 ENVIRONMENTAL SCIENCES
MILL TAILINGS
REMEDIAL ACTION
CONTAINMENT SYSTEMS
WATER INFLUX
BENTONITE
PERMEABILITY
RADIOACTIVE WASTE STORAGE
R CODES
GROUND WATER
DIAGRAMS
STATISTICAL MODELS
SAND
CLAYS
SITE CHARACTERIZATION
CLIMATE MODELS
052002
054000
540230
540250
WASTE DISPOSAL AND STORAGE
HEALTH AND SAFETY
RADIOACTIVE MATERIALS MONITORING AND TRANSPORT
SITE RESOURCE AND USE STUDIES