The LIT was emplaced during 2014 successfully on May 12th 2014. It consists of a solid bentonite (FEBEX and Zn-Montmorillionite) source with radionuclide tracers added in glass vials. The bentonite source was placed into the MI shear zone, which is a known water-conducting zone.

Monitoring of the bentonite colloid formation and the subsequent transport of radionuclides was performed in three dedicated monitoring boreholes and in the existing tunnel outflows such as Pinkel. The hydraulic flow field around the bentonite source was controlled by the continuous outflow at Pinkel.

The emplaced effective swelling pressure of the bentonite is expected to reach approximately 1.05 MPa. The bentonite was built-in as bentonite rings around a mandril. The tracer cocktail contains strongly sorbing tracers (²⁴¹Am, ²⁴²Pu, ¹³⁷Cs) and weakly sorbing tracers (⁹⁹Tc, ⁴⁵Ca, ⁷⁵Se, ²³⁷Np, ²³³U).

The packer system used for the bentonite source was custom-made to allow a later overcoring and therefore disconnection of the packer 3 from the packer 1 and 2. The bentonite source being emplaced between packer 1 and 2.

Final preparation of the bentonite rings and assemblage of the bentonite source

Schematic representation of a bentonite ring interface

Bentonite source emplacement procedure

3D images showing CFM LIT study with CFM 06.002 host of the LIT