Backfill barrier as a component in a multiple barrier nuclear waste isolation system
- 1 May 1980
- report
- Published by Office of Scientific and Technical Information (OSTI)
Abstract
Quantitative estimates of the potential effectiveness of backfill barriers based on a linear sorption model are presented. Using getters such as clays (known sorbents), a backfill approximately 1-foot-thick can delay by 10/sup 4/ to 10/sup 5/ years the breakthrough of transuranics. A delay of 10/sup 3/ years is possible for major cationic fission products. These delays can be achieved provided that (1) the distribution coefficient (K/sub d/, a measure of affinity for sorbed species) for the barrier material is equal to or greater than 2000 ml/g for transuranics and 200 ml/g for fission products; (2) the interstitial groundwater velocity through the barrier is limited to 1 ft/year or less; (3) the effective porosity of the barrier is equal to or less than 0.1; and (4) the physical integrity of the barrier is maintained (no channels or cracks). Mixtures containing expanding clays such as smectites and other getters are expected to satisfy these criteria.Keywords
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