Colloid Formation and Migration : LIT (Long-term In situ Test)

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.

CFM preparation of the bentonite rings 

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

 schematic bentonite ring sml

Schematic representation of a bentonite ring interface

Bentonite source emplacement procedure 

Bentonite source emplacement procedure

 CFM LIT study with CFM 06.002

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

The GTS underground facilities are also available to interested 3rd parties for underground testing and research. The GTS offers cost-effective access to a fully developed, well characterised underground research facility with round the year logistical support - please contact Dr. Ingo Blechschmidt, Head of the Grimsel Test Site, for further details.
You are here: Home GTS Phase VI CFM - Colloid Formation & Migration CFM : LIT (Long-term In situ Test) [2014]