Radiation Protection at the GTS

Recent work at the GTS

A wide range of radionuclide tracers have been successfully applied at the GTS since the building of the laboratory. In Phase V at the GTS, two projects used radionuclides as tracers. These were the Hyperalkaline Plume in Fractured rock (HPF) section, Phase V and the Colloid and Radionuclide Retardation project (CRR) section, Phase V. The CRR project is complete and the final reports are due for publication soon, whereas the HPF project is in the sample analysis stage.

To date all work has been carried out safely, all wastes have been dealt with according to HSK regulations and no doses above the natural background have been received by the workers.

Radionuclides applied in-situ at the GTS

Currently, the Long Term Diffusion (LTD) project utilises a range of radioactive tracers in the various work packages (WP 1, WP 2 and WP 4).

After the success of the on site analysis during the HPF experiment, a new Radiation Controlled Zone has been established in the Central Facility of the GTS. The Level C laboratory is licensed up to the end of GTS Phase VI (in 2013) and provides a great deal of flexibility for the experiments. Preliminary post-mortem analysis of excavated rock material can now be carried out at the GTS.


Pb shields for exposure of Imaging Plates for autoradiography


The BAS 1800i scanner for beta autoradiography

Gamma spectrometer for determination of radionuclide concentration in various sample geometry

Want to know more ?

Please e-mail Dr. Andrew Martin (responsible for radiation protection at the Grimsel Test Site):

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Links for radiation protection.

http://www.bag.admin.ch
Bundesamt für Gesundheit/Swiss Federal Office of Public Health. This is our regulator. (German, French, Italian or English)
 

http://www.iaea.org
The International Atomic Energy Authority
 

http://www.hpa.org.uk/radiation
Some good general information on radiation
 

http://www.icrp.org/
The International Commision for Radiation Protection.
 

 

Fate of Radionuclides at the GTS

The radionuclides we add can have several fates and the waste treatment we use depends on the physical and chemical properties of the radionuclides used.

Much of the work at the Grimsel Test Site (GTS) has involved short half-life tracers, which decay very quickly to non-radioactive forms. Radioactive tracers with longer half lives are taken to the Paul Scherrer Institute (PSI) for treatment and final disposal.

Removal of cores from the excavation Project
Removal of cores from the Excavation Project

In specific cases (e.g. Excavation Project), where the radionuclides are held very tightly by the rock, the whole rock mass can be immobilised via injection of an epoxy resin. The area of rock containing the radionuclides is then physically removed by taking large (30 cm diameter) cores of rock (which also contains the radionuclides) from the GTS.

Animation of overcoring procedure at the GTS
Overview of the overcoring procedure

The extracted cores can then be analysed by very precise radiochemical techniques, which allow the sites of radionuclide retardation to be observed.

 

Monitoring of Radioactivity at the GTS

Every person working in the radiation controlled zone (whether as level B or C) wears a detector that records any radiation dose that they receive. This badge is called a thermo-luminescence detector (TLD). The area within the laboratory is also monitored using state-of-the-art instruments that measure the radiation levels within the laboratory and also with contamination monitors to ensure no spillages have occurred. Computer systems linked to very precise measuring equipment monitor the radionuclide tracers in the groundwater in real time.

Monitoring Equipment at the GTS
Monitoring equipment at the GTS

We have received clearance from ENSI for the use of transuranics radionuclides in the GTS. This is based on the successful application of "simpler" radionuclide tracers in previous experiments and the GTS is, to date, the only underground rock laboratory in the world where transuranics radionuclides can be added directly to the ground water.

All the work carried out in the controlled zone is strictly regulated now by BAG and permission is needed before any work involving radionuclides commences.
 

The GTS underground facilities are also available to interested 3rd parties for underground testing and research. The GTS offers cost-effective access to a fully developed, well characterised underground research facility with round the year logistical support - please contact Dr. Ingo Blechschmidt, Head of the Grimsel Test Site, for further details.
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