Nirma Project – Non Ionising Radiation Mapping & Assessment at CERN

The NIRMA Project Non-Ionising Radiation Mapping & Assessment at CERN (NIRMA)

As part of its continuous commitment to health, safety, and transparency, CERN is carrying out the Non-Ionising Radiation Mapping and Assessment (NIRMA) project.

The objective of NIRMA is to StartFragment create a map of the electric and magnetic fields on CERN premisesEndFragment and to ensure that electromagnetic field (EMF) levels remain within applicable safety limits for:

• CERN workers,
• users of CERN facilities,
• authorised visitors present on site,
• and in particular users of Active Implantable Medical Devices (AIMDs) such as pacemakers, implantable cardioverter-defibrillators (ICDs), and neurostimulators.

Electromagnetic fields are a common feature of technical and industrial environments and are generated by electrical installations, power systems, and communication equipment. The NIRMA project provides a structured and preventive approach to managing these fields at CERN.

What is being measured?

The NIRMA project focuses on electromagnetic fields, which are a form of non-ionising radiation. These fields span a wide frequency range and differ from ionising radiation, as they do not cause ionisation or changes in atomic structure.

StartFragment Electromagnetic fields are harmless and play essential roles in our mobile networks and energy infrastructure, but very strong fields such as those used at CERN can interfere with metallic or electrical equipment such as medical implants.EndFragment

How are the measurements performed?

Measurements are carried out using a vehicle equipped with calibrated electromagnetic field probes, operated along selected CERN roads and other accessible areas within CERN premises.

The mobile measurement system installed on the vehicle is called TURTLE:

TURTLE – Top-mounted Unit for NIR Time-averaged Field Level Evaluation

As the vehicle moves, electromagnetic field levels are recorded continuously, allowing CERN to build a map of the electromagnetic environment across the site under representative operating conditions. It needs to drive slowly to do this effectively.

The measurement system:

• does not record images, audio, personal data, or vehicle information,
• does not emit any electromagnetic fields,
• performs purely passive measurements of the existing environment.

Why is the vehicle driving so slowly? TURTLE in operation! During the measurement campaign, the vehicle may operate at reduced speed. This is intentional and necessary to ensure measurement accuracy. The driving speed depends on: the frequency range being measured, and the sampling rate and time-averaging requirements of the monitoring equipment. Driving too fast would reduce the number of samples collected per location and could affect data quality. The selected vehicle speed therefore represents a balance between measurement accuracy and operational practicality.

Frequency ranges covered

To characterise the electromagnetic environment relevant for CERN activities, measurements are performed using two interchangeable probes covering complementary frequency ranges:

Low-frequency range: 10 Hz – 3 kHz

This range is mainly associated with:

• electrical power systems,
• large currents,
• transformers and industrial installations.

High-frequency range: 100 kHz – 8 GHz

This range is mainly associated with:

• communication systems and antennas,
• wireless technologies,
• certain accelerator-related and technical equipment.

Together, these ranges cover the dominant electromagnetic field sources present in accessible areas on CERN premises.

Why is the frequency range between 3 kHz and 100 kHz not included?

The intermediate frequency range between 3 kHz and 100 kHz is not included in the mobile mapping phase for the following reasons:

• At CERN, very few installations generate significant electromagnetic fields in this range in accessible areas.
• Sources operating in this band are typically localised and equipment-specific, making them better suited for targeted, local measurements rather than wide-area mobile surveys.

Where specific equipment or situations justify it, dedicated measurements in this intermediate frequency range can be carried out as part of a focused assessment.

Mobile mapping and identification of areas of interest

The NIRMA project follows a progressive, data-driven methodology.

Mobile mapping provides a site-wide overview of electromagnetic field levels and allows the identification of areas of interest, i.e. locations where levels are higher than the surrounding background.

Based on these results, further actions may include:

• targeted on-site detailed measurements, and
• the selection of locations for fixed monitoring stations for long-term follow-up.

This approach ensures that detailed assessments are focused where they are most relevant, while maintaining a high level of safety, transparency, and regulatory compliance.

Regulatory framework

NIRMA measurements and assessments are performed in accordance with applicable Swiss, European, and French regulatory frameworks, as well as internationally recognised scientific guidelines, including:

• Swiss Ordinance on Protection from Non-Ionising Radiation (ORNI, RS 814.710),
• EU Directive 2013/35/EU,
• French Decree No. 2002-775 of 3 May 2002,
• ICNIRP guidelines.

These references form the basis for interpreting measurement results and verifying compliance.

Project ownership and contact

The NIRMA project is conducted under the responsibility of the HSE-OHS-GI section, with support from the ATS Electromagnetic Compatibility (EMC) forum.

For further information, please contact:
Igor Neuhold
Project Leader – NIRMA
CERN, HSE-OHS-GI