During the EU project NF-Pro (www.nf-pro.org), an experiment chamber was developed to control and monitor air temperature and humidity as well as the mass of a rock overcore (Fig. 1). Additionally, the cores were equipped with self made single-rod TDR (time domain reflectometry) probes.

 

 Figure 1: Photographs of a granite overcore from GTS (a) and an Opalinus clay overcore from Mont Terri URL (b) standing on a balance inside the drying chamber at GTS.

 

The drying chamber is used for two purposes (Fig. 2):

 

1) to monitor the desaturation of large overcores (e.g. granite matrix, fractured granite or Opalinus clay) under controlled humidity conditions. This provides insight into 2-phase flow properties for host rock specimens that are much larger than the common core samples and thus much more representative. As a consequence, the test duration usually is much longer. For example, a test with an Opalinus clay sample from the Mont Terri rock laboratory is running since August 2007 (Fig. 1/b).

 

2) to calibrate TDR probes developed at Nagra and to further develop interpretation techniques for their data records.

 

Figure 2: Schematic picture of drying chamber and data acquisition