Most of the proposed techniques for chemical shielding of
radioactive waste implies use of smectite clay, which degrades according to a well-known
scheme. Since such “buffer” clay has to serve for many thousands of years, the
mechanisms in the unavoidable long-term degradation process must be understood
and accounted for as described in the paper. In addition to conversion of
smectite to non-expandable minerals cementation by precipitation of siliceous
matter created in the degradation process is of concern since it can reduce the
self-sealing capacity of desiccated or mechanically damaged clay.
Smectite clays, diffractogram, radioactive wastes, montmorillonite,
XRD, TEM, Holmehus clay.