At the Grimsel Test Site (GTS), we carry out experiments with radionuclides as tracers of the processes in the rocks. Radionuclide tracers are very useful because we can detect them at much lower concentrations than non-radioactive tracers and because they provide individual "fingerprints" which allow us to follow natural mechanisms in the rock and groundwater unambiguously and this makes our experiments more useful than if we used non-radioactive tracers

In addition, use of radioactive tracers in the GTS allows us to study safety-relevant radionuclides in an environment analogous to that of a real radioactive waste repository

What is radiation protection?

Radiation protection is ensuring that the use of radionuclide tracers at the GTS does not harm the people who work and visit the GTS and ensures that there is no contamination of the environment. We follow very strict regulations set by HSK (Hauptabteilung für die Sicherheit der Kernanlagen/Swiss Federal Nuclear Safety Inspectorate) and all work with radionuclides is supervised by a Radiation Protection Officer (RPO).

We wish to thank HSK for their continued support of our work at the GTS.

Safe use of radionuclides at the GTS

In 1988, a special area of the GTS tunnels was designated as a radiation controlled zone and this conforms to regulations laid down by HSK regarding the safe handling and use of radionuclides. In the unlikely case of an accident, the controlled zone would ensure minimal contamination to the GTS and any staff or visitors present.

Location of controlled zone on GTS map and picture of gate

In normal experiments, the lab operates as a Level C radiochemistry laboratory. The staff working in the controlled zone are monitored for any contamination and all material is handled according to strict regulations.

In addition, our laboratory can routinely be upgraded to a Level B radiochemistry laboratory. This is used when higher activities of radionuclide tracers are required when alpha-emitting radionuclides are used or the set-up of the experiment poses a greater radiological risk to the workers (e.g. during excavation of rock cores as in the Excavation Project). The requirements of a level B lab are:

• Protective clothing must be worn when working in the controlled zone.
  
  
• There is a special changing area at the entrance to the lab.
  
  
• All people and equipment coming in and out of the laboratory are monitored.
  
  
• The air supply within the laboratory is separate to that for the rest of the GTS, is maintained under atmospheric pressure (to contain any possible contamination) and is filtered with any particles trapped in these filters monitored for radiation.

Tracer injection during the EP Project