The FEBEX project at the
Grimsel Test Site (GTS) has been established as a large scale experiment
focusing on:
Demonstrating the feasibility of actually manufacturing
and assembling an engineered barrier system based on the
Spanish SF disposal concept for a crystalline host rock.
Developing methodologies and models for assessment of
the thermo-hydro-mechanical (THM) and thermo-hydro-geochemical
(THG) behaviour of the engineered barrier system (near field).
As part of the FEBEX site instrumentation,
Nagra took responsibility for the installation of a TDR (Time
Domain Reflectometry) system for measuring the water content
changes in both the bentonite backfill and the granite rock
formation. The TDR system was emplaced in summer 1996; long-term
monitoring of water content started immediately after sensor
emplacement.
Febex TDR Monitoring
The FEBEX project formally ended in December 2004, but the in-situ
work is carried on within the frame of the EC integrated NF-Pro
project (cf. www.nf-pro.org
).
The integrated THM (C) experiment at real scale - actually started
on 1st of January 2005. A vital aspect of Nagra's involvement is,
beside the further monitoring of water content changes in the bentonite
buffer, the refinement of the TDR technique as a method for water
content measurements in low porosity rock formations.
