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

Abstract

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 thatmore » 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.« less

Authors:
; ;
Publication Date:
Research Org.:
Brookhaven National Lab., Upton, NY (USA)
OSTI Identifier:
5158859
Report Number(s):
BNL-NUREG-30107; CONF-810499-2
ON: TI86000935
DOE Contract Number:  
AC02-76CH00016
Resource Type:
Technical Report
Resource Relation:
Conference: National Bureau of Standards workshop of R and D needs in backfill for nuclear waste repositories, Gaithersburg, MD, USA, 13 Apr 1981
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; BACKFILLING; EVALUATION; HIGH-LEVEL RADIOACTIVE WASTES; RADIOACTIVE WASTE DISPOSAL; ZEOLITES; SORPTIVE PROPERTIES; DIFFUSION; EXPERIMENTAL DATA; FEASIBILITY STUDIES; GROUND WATER; RADIONUCLIDE MIGRATION; SORPTION; THICKNESS; TITANATES; DATA; DIMENSIONS; ENVIRONMENTAL TRANSPORT; HYDROGEN COMPOUNDS; INFORMATION; INORGANIC ION EXCHANGERS; ION EXCHANGE MATERIALS; MANAGEMENT; MASS TRANSFER; MATERIALS; MINERALS; NUMERICAL DATA; OXYGEN COMPOUNDS; RADIOACTIVE MATERIALS; RADIOACTIVE WASTES; SURFACE PROPERTIES; TITANIUM COMPOUNDS; TRANSITION ELEMENT COMPOUNDS; WASTE DISPOSAL; WASTE MANAGEMENT; WASTES; WATER; 052002* - Nuclear Fuels- Waste Disposal & Storage

Citation Formats

Ahn, T M, Dayal, R, and Wilke, R J. Evaluation of backfill as a barrier to radionuclide migration in a high level waste repository. United States: N. p., 1981. Web.
Ahn, T M, Dayal, R, & Wilke, R J. Evaluation of backfill as a barrier to radionuclide migration in a high level waste repository. United States.
Ahn, T M, Dayal, R, and Wilke, R J. Thu . "Evaluation of backfill as a barrier to radionuclide migration in a high level waste repository". United States.
@article{osti_5158859,
title = {Evaluation of backfill as a barrier to radionuclide migration in a high level waste repository},
author = {Ahn, T M and Dayal, R and Wilke, R J},
abstractNote = {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.},
doi = {},
url = {https://www.osti.gov/biblio/5158859}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1981},
month = {1}
}

Technical Report:
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