The second stage was to remove the bentonite blocks to allow removal of the first heater. This task required careful work to avoid disturbing the monitoring instrumentation installed within the Engineered Barrier System (EBS).

A careful sampling program was also carried out to examine the properties of the bentonite after 4 years of heating and hydration.

Exposure of the bentonite blocks behind the concrete plug
Close up of the bentonite blocks, note the lack of gaps between the blocks

During the original emplacement of the EBS, gaps could be seen between the. bentonite, these then sealed up as the clay expanded due to hydration with groundwater (October 1996)
Compare the original gaps (shown left) to the situation found when excavating in June 2002

Sampling of the bentonite was carried out
Cores of bentonite removed from the EBS


Full-scale High Level Waste Engineered Barriers (FEBEX) - Excavation Phase