Radiation monitoring

Ionising radiation from radioactive sources can be very dangerous for humans and their environment. Therefore, it is important to take measures to protect oneself from its harmful effects. The most common radiation protection measures include shielding, evacuation and the use of personal protective equipment. By taking these precautions, we can minimise our exposure to ionising radiation and help keep ourselves and our communities safe.

What is radiation monitoring ?

Radiation protection refers to all the measures taken to ensure the protection of humans and their environment against the harmful effects of exposure to ionising radiation: alpha, beta, gamma and X-rays.

• Exposure to radiation

Certain types of radiation (alpha, beta, gamma and X-rays) are said to be "ionising" because they carry enough energy to cause a change in the electrical charge of the atoms through which they pass (ionisation phenomenon). Exposure therefore corresponds to the interaction of ionising radiation with matter. Exposure is usually low, but in the event of an accident, for example, people may be exposed to high doses of radiation.

• Irradiation

External exposure causes external radiation. This can be controlled by the duration of exposure, the distance to the radiation source and the use of protective shielding.
A person exposed to an external source of radiation (such as an X-ray) will never carry any trace of radioactivity.

• Contamination

Radioactive contamination is often defined as "the unwanted presence of radioactive substances on the surface of or within any medium, including the human body".
Contamination is necessarily the result of the dispersion of a radioactive substance, for example, as a result of careless handling.
Radioactive substances come from a wide variety of sources and can be in solid, liquid or gaseous form.

* Source: Essential information on radiation protection - CEA (Commissariat à l'Energie Atomique et aux Energies Alternatives)

Regulatory framework on radiation protection

The regulatory framework concerning the protection of workers against the effects of ionising radiation is based on the harmonisation of national regulations, the Public Health and Labour Codes and European Directives. This framework also follows the recommendations of the International Commission on Radiological Protection (ICRP).

The ICRP recommendations relate to three general principles:

• the justification of activities that lead individuals to be exposed to radiation
• optimisation of protection,
• limitation of individual doses (ALARA concept: As Low As Reasonably Achievable).
   

How to protect workers and the public from ionising radiation?

The implementation of surveillance, prevention, protection and access control measures in risk areas aims to prevent or limit the effects of ionising radiation received by workers and the public.

Radiation protection measures

• Contamination control using systems and equipment to monitor the contamination of people, objects or surfaces that have been exposed to radioactivity.
• Access control via radiological control systems for people and vehicles (portal detector)
• Environmental monitoring through the use of monitoring solutions by measuring radioactivity in the air, water, soil or in gaseous and liquid effluents.

Radiation protection instruments

Passive dosimetry

Dosimetry is mandatory for all workers likely to be exposed to ionising radiation (in supervised or controlled areas).
The reading of the doses received is accumulated over a predefined period.
Several technologies co-exist: radiophotoluminescence (RPL), optically stimulated luminescence (OSL), thermally stimulated luminescence (TLD).
 

Active or operational dosimetry

Active dosimetry is mandatory for access to controlled areas. Complementary to passive dosimetry, it allows real-time measurement of the dose rate and the integrated dose equivalent.

A series of alarms integrated into the dosimeter alerts the worker or the control centre if the individual dose or dose rate reaches predetermined thresholds.
 

Radiation survey

Portable radiometry is used for contamination detection and allows quick and immediate measurements of X-ray, gamma and neutron radiation in the field. It is an additional support for the protection and safety of workers during interventions.