Voir en


X-ray imaging in progress: keep clear!

Radiography on the CERN site
Industrial radiography under way at CERN. The safety cordon is there for your safety – never cross it except under the supervision of a qualified radiation worker! (Image: CERN)


Industrial radiography is a non-destructive testing technique used widely at CERN to examine the internal structure of samples ranging from welds to structural elements of buildings. It uses high-energy radioactive sources or an X-ray generator to examine the structure and integrity of samples in a non-destructive way. It is widely deployed at CERN by the Engineering department’s Mechanical and Materials Engineering (EN-MME) group to examine structures as diverse as the piping that feeds fuel to the new diesel groups close to Entrance B and welds in the fire extinction network of the new Building 311. The work may be outsourced to one or more companies, depending on the workload at any given time.

Radiography can be carried out anywhere on the CERN sites, indoors or outdoors, including in areas where you would not normally expect to encounter radiological hazards. Where radiography is planned, it is clearly announced through the IMPACT procedure and the relevant TSO, building occupants and others who may be immediately concerned are informed. If you are not informed in this way, you will still be able to identify the area where the radiography is taking place. It will be clearly cordoned off and there will be clearly visible information panels displaying telephone numbers that you can call for further information. Radiographical examinations normally take place outside working hours, between 7 p.m. and 6 a.m.

All radiographical procedures at CERN are carried out according to the internationally-accepted ALARA (As Low As Reasonably Achievable) principle, which ensures that every intervention is necessary, with radiation doses limited and optimised. Each campaign is painstakingly prepared. Nevertheless, within the marked-off area, there is a risk of exposure to very high levels of radiation, and it is therefore important to respect the safety cordon.

Remember, at CERN, we are each responsible for our own safety. If you see a cordon indicating that radiography is in progress, do not cross it. Only qualified radiation workers carrying out the inspection are authorised to do so.

If you have to cross the area for work or personal reasons – if you have parked your car on the other side, for example – call one of the phone numbers on the information panels. A qualified radiation worker will help you cross the zone safely.

Last but not least, if you have not done so already, follow the e-learning course “Radiation Protection – Awareness”, which is now obligatory for everyone working on the CERN sites.