∙the presence of an unlocking device which can be actuated from inside the rooms in which particle accelerators are used; ∙the correct operation of the audio signal associated with the in-situ check process to ensure nobody is in the room before the emission of ionising radiation can be enabled; ∙the presence of locks with captive keys on the control console(3) and on all the accesses to the rooms in which particle accelerators are used. Although the main access is always equipped with this type of lock, this is not always the case for the secondary access points which are used more occasionally; ∙the control of the technical means (password, dedicated key, etc.) allowing the safety systems to be overridden in the context of highly specific maintenance and servicing procedures. These means must be monitored constantly to ensure they are not used otherwise than for these specific procedures; ∙the availability of radiation monitoring devices in sufficient quantities for the operators who access these rooms and the keeping of these devices in good working order. Lastly, with regard to experience feedback, two Significant Radiation Protection Events (ESRs) were reported to ASN in 2024 by facilities using particle accelerators for scientific research purposes: ambient environment measurements taken by the licensees revealed exposure levels that were higher than usual and incompatible with the radiological zones in place on their premises, including in areas that were not subject to radiological zoning. In the first case, the event was caused by a change in the experimental conditions of use without informing the RPE. The second case was caused by a maintenance operation on the accelerator that led to a malfunction: the anomaly was detected at an early stage in the maintenance process. These two events, which were well managed from the radiation protection viewpoint, did not lead to overexposure of persons. Furthermore, recurrent events linked to the use of particle accelerators during customs cargo checks were reported to ASN, as happens each year. When conducting these checks, the customs services take precautions (such as broadcasting information messages in several languages) to avoid the unjustified irradiation of people who could be hiding in these vehicles (see point 3.3.1). However, despite these 3. One and the same key can be used to gain access to the room and render operational the accelerator’s control console. Furthermore, these keys cannot be removed from the access door locks if the doors are open. 4. Among these inspections, 17 exclusively concerned the use of sealed radioactive sources or electrical devices emitting ionising radiation. precautions, the customs services regularly notify ASN of events relating to the exposure of people hidden in checked vehicles. Although this exposure is unjustified, it nevertheless remains extremely low with effective doses of just a few microsieverts per person. 3.4 Research activities involving unsealed radioactive sources 3.4.1 The devices used In the research sector, as at 31 December 2024, ASN counted 318 licenses and 174 registrations issued under the Public Health Code, of which nearly 90% are issued to public or mixed (public/private) entities. The number of licenses is constantly decreasing, essentially due to the replacement of ionising radiation sources by alternative technologies that do not use ionising properties, but also to the changes in the system introduced in the last few years. Since 2019, certain nuclear activities have switched from the licensing system to the notification system (see point 2.4.2) and, since July 2021, other activities are now subject to the registration system (see point 2.4.3). This new system addresses in particular the possession/use of unsealed source which until then were governed solely by the licensing system. The complete transitions of research laboratories from the licensing system to the registration system will continue over the coming years, particularly for the laboratories that reduce the quantities of radio- nuclides handled. These facilities and laboratories use mainly unsealed sources for medical and biomedical research, molecular biology, the agrifood business, the sciences of matter and materials, etc. They can also be suppliers of unsealed sources. They also use sealed sources for performing gas-phase chromatography, liquid scintillation counting or in irradiators. Electrical devices emitting ionising radiation are also used for X-ray fluorescence or X-ray diffraction spectrum analysis. Particle accelerators are used in research into matter or for the production of radionuclides. 3.4.2 Evaluation of the radiation protection situation In 2024, ASN carried out 43 inspections in this sector(4) (compared with 52 inspections per year on average over the 2022‑2024 period). Broadly speaking, the actions undertaken over the last few years have brought improvements in the implementation of radiation protection within research laboratories. However, this trend is slowing down, with recurrent nonconformities persisting from one year to the next, as is the case with waste management for example. Even if the standard of radiation protection in the research laboratories remains broadly satisfactory, it remains dependent on the involvement of the individuals designated as RPEs and the means at their disposal. The radiation risks in many research laboratories are fairly low or tending to decrease, resulting in their nuclear activity changing from the Synchrotrons Belonging to the same family of circular particle accelerators as the cyclotrons (see point 4.2), the synchrotron, which is much larger, can attain energy levels of several gigaelectronvolts by using successive accelerators. Owing to the low mass of the particles (generally electrons) the acceleration created by the curvature of their trajectory in a storage ring, produces an electromagnetic wave when the speeds achieved become relativistic: this is synchrotron radiation. This radiation is collected at various locations called beam lines and is used to conduct scientific experiments. Research activities The use of ionising radiation in research activities extends to various fields such as medical research, molecular biology, the agri-food industry, materials characterisation, etc. It primarily involves the use of unsealed sources (iodine-125, phosphorous-32, phosphorous-33, sulphur-35, tritium-3, carbon-14, etc.). Sealed sources (barium-133, nickel-63, caesium-137, cobalt-60, etc.) are also used in gas chromatographs or scintillation counters or, with high-level sources, in irradiators. X-ray generators rays are used for X-ray fluorescence or X-ray diffraction spectrum analyses. The use of scanners for small animals (cancer research) in research laboratories and faculties of medicine should also be noted. Particle accelerators are used in research into matter or for the manufacture of radionuclides. ASN Report on the state of nuclear safety and radiation protection in France in 2024 269 11 12 13 14 15 AP 10 09 Sources of ionising radiation and their industrial, veterinary and research applications 08 01 02 03 04 05 06 07
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