Evaluation of backfill as a barrier to radionuclide migration in a high level waste repository

Technical Report · Thu Jan 01 04:00:00 EST 1981

OSTI ID:5158859

Ahn, T M; Dayal, R; Wilke, R J

The feasibility of using highly sorptive synthetic minerals such as zeolites or titanates as backfill in a HLW repository has been evaluated in terms of the NRC 1000 yr containment and 10/sup -5//yr controlled release criteria. The results indicate that for groundwater velocities below 1 ft/yr, diffusion and sorption are the dominant processes controlling radionuclide migration in backfill systems. A 3-ft-thick bed of synthetic zeolite backfill can provide total containment of activity released continuously from a 55-gallon glass monolith for a period of up to 1000 years. In the absence of the waste form as an engineered barrier, a bed thickness of 3 to 10 ft is required to satisfy the controlled release criterion for a period of up to 10/sup 5/ years. With a bed thickness of 200 ft, synthetic zeolites can be used as backfill to provide containment of the total US waste inventory (10/sup 9/ Ci), if it were placed in one repository, for periods up to 10/sup 6/ years. Zeolites are known to exhibit radionuclide-specific sorption properties. We believe that the range of sorption coefficients (10/sup 3/ to 10/sup 4/ ml/g) considered in the calculations will cover the various zeolite-radionuclide systems. We wish to emphasize that the above estimates are conservative since diffusion occurs radially and we have only considered uni-dimensional transport in our models. In addition, radioactive decay of the nuclides has not been considered in the calculations. We also wish to note that in this report we have not dealt with radiation and thermal stability of backfill materials. It appears that other materials will have to be added to backfill to maximize its effectiveness for retention of all radionuclides of interest. 23 refs., 3 figs., 7 tabs.

• Research Organization: Brookhaven National Lab., Upton, NY (USA)
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 5158859
• Report Number(s): BNL-NUREG-30107; CONF-810499-2; ON: TI86000935
• Country of Publication: United States
• Language: English

Related Subjects

052002* -- Nuclear Fuels-- Waste Disposal & Storage
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
BACKFILLING
DATA
DIFFUSION
DIMENSIONS
ENVIRONMENTAL TRANSPORT
EVALUATION
EXPERIMENTAL DATA
FEASIBILITY STUDIES
GROUND WATER
HIGH-LEVEL RADIOACTIVE WASTES
HYDROGEN COMPOUNDS
INFORMATION
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MANAGEMENT
MASS TRANSFER
MATERIALS
MINERALS
NUMERICAL DATA
OXYGEN COMPOUNDS
RADIOACTIVE MATERIALS
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTES
RADIONUCLIDE MIGRATION
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
THICKNESS
TITANATES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES
WATER
ZEOLITES