The KBS-3 method. The method involves encapsulating the spent fuel in copper canisters which are then emplaced, surrounded by a buffer of bentonite clay, in deposition holes in a tunnel system at a depth of 400–700 m in the bedrock (SKB, 2011, reproduced with permission). BWR: boiling water reactor.
Two options for disposal according to the Canadian concept: the containers will be placed in vertical boreholes drilled in the ground along the axis of a placement room, or placed horizontally within the confines of a placement room, depending on the nature of the rock and characteristics of the site (from Nuclear Waste Management Organization, 2012; reproduced with permission).
View of the Swiss concept for a SF/HLW/ILW repository in the Opalinus clay with inset of SF canister-emplacement tunnel and longitudinal section of emplacement tunnels for SF for the design option using low-pH shotcrete tunnel support. SF: spent fuel; HLW: high-level waste; ILW: intermediate-level waste (Copyright Nagra)  (Nagra, 2002).
Heat conductivity (λ) of laboratory-scale bentonite samples as a function of saturation ratio (Sr) for a number of values of the void ratio (e) (from Börgesson et al., 1994; reproduced with permission).
Equilibrium pressure vs. temperature for Dep-Can (Ibeco RWC) bentonite at a swelling pressure of ~7 MPa at temperatures >0°C. The freezing point (Tc) of the sample is below 8°C. The line labeled ‘Theory’ shows the expected pressure response if the water-saturated bentonite is treated as thermodynamically equivalent to a salt solution (from Birgersson et al., 2010; reproduced with permission).
Swelling pressures of MX-80 exposed to NaCl solutions (upper) and Ibeco RWC (Deponit CA-N) exposed to CaCl2 solutions (lower). Concentration expressed as M (from Karnland et al., 2006; reproduced with permission).
Degree of saturation and dry density for a buffer ring at canister mid-height after test dismantling. Experimental and model results (from Zandarin et al., 2012; reproduced with the permission of Elsevier).
Smectite content vs. depth in smectite-illite mixed-layer material in two sediments representing relatively fast burial rate (left) and slow burial rate (right). T.G. indicates the present temperature gradient and B.R. indicates the burial rate (after Velde and Vasseur, 1992; reproduced with permission).