High level waste compacted bentonite

Bradbury, M. H. Baeyens, B. 2002a. Near-Field Sorption Data Bases for Compacted MX-80 Bentonite for Performance Assessment of a High Level Radioactive Waste Repository in Opalinus Clay Host Rock. Nagra Technical Report NTB 02-18, Nagra, Wettingen, Switzerland. Also issued as PSI Bericht Nr. 03-07, Paul Scherrer Institut, Villigen, Switzerland. 

Figure 13.33 Schematic diagram of the engineered barrier system (BBS) showing the high-level nuclear waste in its metal container, surrounded by a buffer or backfill (usually of compacted bentonite clay), in contact with the host rock. The BBS and rock affected thermally by the waste are sometimes termed the near field, with more distant surrounding rock termed the far field. After The status of near field modeling. Proc. Technical Workshop, copyright 1995 by OECD. Used by permission.

The engineered barriers are composed of vitrified waste encapsulated in a canister, metal overpack and buffer material in a geological disposal system of high-level radioactive waste (HLW) adopted by INC (2000). Highly compacted bentonite is considered as the candidate buffer material for the system. Figure I shows the schematic view of the geological disposal system and expected processes after emplacement of the engineered barriers. 

---