A series of laboratory experiments are also being carried out by JNC (now JAEA).

Both column and batch experiments are underway to examine the alteration of the Grimsel rocks (fault gouge and Grimsel granite). The experimental set up is shown below.

Samples from the alteration experiments were then examined using a Scanning Electron Microscope (SEM). The images below clearly show the alteration of the samples subject to percolation of high pH solution.

SEM Analysis of high pH-altered rock

Experiments are also being carried out to examine the effect of overcoring techniques on the shear zone. The technique planned for overcoring involves injection of isopropanol followed by epoxy resin to stabilise the core prior to overcoring. Although these techniques have already been carried out at the GTS, the previous experiments were under normal Grimsel conditions and not the high pH conditions present for the HPF experiment. The current lab work includes the effects of isopropanol and epoxy resin injections on any secondary phases that may be present.