Swedish Nuclear Fuel and Wast Management Co. (SKB), Sweden
The FEBEX (Full-scale Engineered Barriers Experiment ) experiment at the Grimsel Test Site consists of an in-situ full-scale Engineered Barrier System (EBS) test performed under natural conditions. A "mock-up" test, at almost full scale runs in parallel in the laboratories at Ciemat in Madrid. With the start of the heating in 1997, the FEBEX experiment is the longest running full-scale experiment in the world leading to a unique dataset.
The FEBEX experiment has been the research subject in three subsequent European research projects: FEBEX, FEBEX II and NF-PRO, under the leadership of Enresa (Spain). Starting in 2008, a consortium of four partners (SKB, Ciemat, Posiva and Nagra) was brought together which continues running the in situ experiment and the mock-up as part of Grimsel Phase VI under the name FEBEXe until 2012, when excavation of the second
heater is planned.
Project history and future of the FEBEX in situ experiment
The experiment is based on the Spanish reference concept for the disposal of high level radioactive waste in crystalline rock in which the canisters enclosing the conditioned waste are placed horizontally in drifts and surrounded by a swelling clay barrier constructed of highly compacted bentonite blocks.
With the start of the heating in 1997, the FEBEX experiment (heater No. 2 and EBS; see Fig. 4) is the longest running full-scale experiment. A constant temperature of 100°C has been maintained at the heaters/bentonite contact during this time, while the bentonite buffer has been slowly hydrating with the water naturally coming from the rock. A total of 632 sensors of diverse types were installed in the clay barrier, the rock mass, the heaters and the service zone to measure the following variables: temperature, humidity, total pressure, displacement, pore pressure etc.
Partial dismantling of the in-situ test was carried out during 2002. After five years of heating, heater No. 1 was removed and the materials recovered (bentonite, metals, instruments, etc.) have been analysed to investigate the different types of processes undergone, while the second heater continued.
The current lay-out of the FEBEX in situ test
For more information please contact: Irina. Gaus