Ionising radiation is constantly monitored inside and outside the CERN perimeter. The Laboratory operates an extensive network of environmental radiation monitors and online sampling systems. In 2022, the environmental monitoring programme included 130 measuring stations comprising 640 monitoring channels, 494 of which are dedicated to radiological monitoring.

This robust radiation monitoring infrastructure is underpinned by the Radiation and Environment Monitoring Unified Supervision (REMUS) tool. This innovative system developed by CERN provides supervision, control and data acquisition for the entire suite of monitoring stations and is continually upgraded to ensure that it evolves with the Organization’s needs.

The methods used to evaluate the doses that members of the public could potentially receive are based on widely recognised models and standards and consider the specific nature of CERN’s facilities. A revision of the models was completed in 2022 and was agreed with the Host States authorities. The revised models will be used from now on for all future assessments of CERN’s radiological environmental impact.

CERN collaborates with the Host States to allow their own services to monitor stray radiation and environmental radioactivity inside and outside the CERN perimeter. A network of thermoluminescent dosimeters for assessing ionising radiation around the sites is completed by a high-volume aerosol sampler for sensitive laboratory analyses. A monitoring device on CERN's Meyrin site sends real-time data to the Swiss Federal Office of Public Health (FOPH). In addition, the FOPH conducts annual site measuring campaigns.

Heinz Vincke is the deputy leader of the CERN Radiation Protection group.

— With accelerators moving towards higher intensity over time, what are the main implications for radiation protection?

HV: Higher intensity would inevitably lead to more radiation. To mitigate this, we have a formalised approach to optimising the design of entire installations and to work coordination, work procedures and the handling of tools.

— What approaches and tools are used for optimal radiation protection management?

HV: During the design stage, we must choose the right materials, shielding and location to minimise the amount of radiation. We mainly use computer-based simulations to ensure optimised dose reduction for personnel and the environment. Furthermore, we use the ActiWiz software, which was developed by the CERN Radiation Protection group. It applies a customised risk assessment model to allow us to choose materials with low activation risks. CERN has developed additional tools that allow us to respect most stringent regulations, such as OPEDOSI for monitoring operational doses received by personnel working in radiation areas, TREC for recording and tracing radioactive material and RAISIN, a database covering all radiation areas at CERN.

The Intervention Management Planning and Activity Coordination Tool (IMPACT) facilitates the assessment of risk, including radiation risk, and ensures a formalised approval process for work in radiation areas. The radiation monitoring tools REMUS (Radiation and Environment Monitoring Unified Supervision) and ERGO (Environment and Radiation Graphic Observer), the visualisation counterpart of REMUS, are further examples of the comprehensive suite of tools in place.

— What about repairing equipment?

HV: The repair of equipment brings specific challenges, especially when we need to work in high-activation areas. For some installations, we can handle equipment or do repairs remotely using robots. When this is not possible, we optimise the work procedure and tools, for example by using mock-up models, so that the time spent in the area of concern is kept to the minimum.

Thanks to this comprehensive approach, CERN has succeeded in continuously reducing the doses to which its personnel and the environment are exposed over the last decade.

Questions regarding this report may be addressed to environment.report@cern.ch.