Survey and review of near-field performance assessment

Although buffering can result by interaction of groundwater with all the materials in the engineered barrier structures (EBS) for nuclear waste repositories, the buffering properties of bentonite may be particularly important for two reasons. The first is that bentonite backfill will physically separate the host rock from other components of the waste package. Bentonite's mineralogy is the second reason. In considering the reaction between pore water and compacted bentonite backfill (dominated by smectitic clay), a number of tests have been conducted, and a number of alternate conceptual models have been developed. These models are summarized. (R.P.)