The impact of these events on the people living near the sites remained limited and very far below the regulatory annual dose limit for the public (1 mSv). These two events led to an incident notice published on the ASN website and were rated level 1 on the INES scale. The site on which discharge limits were exceeded over several months was moreover given formal notice to restore a compliant situation. There are disparities in the technical and organisational means implemented by the licensees, depending on the age of the facilities and the type of activities performed (research or industrial production). Experience feedback in this area has led ASN, assisted by IRSN, to draw up a draft regulatory text on the technical design and operating rules applicable to companies producing radionuclides using a cyclotron. This draft text was made available for consultation by the stakeholders in 2016. A revised version was produced in 2018, taking account of the observations received and including additional chapters on the control and monitoring of gaseous effluent discharges. This second version of this draft underwent a new consultation by the stakeholders in 2019. Preparation of this draft text will continue in 2022, taking into account the discussions held with the DGT in 2019 and information provided by IRSN in 2020 in order to establish a single regulatory baseline for the entire sector of activity concerned. The main conclusions of this regulatory work are already being used in the examination of license applications in order to include appropriate individual license conditions. CYCLOTRONS A cyclotron is a device 1.5 to 4 metres in diameter, belonging to the circular particle accelerator family. The accelerated particles are mainly protons, with energy levels of up to 70 MeV. A cyclotron consists of two circular electromagnets producing a magnetic field and between which there is an electrical field, allowing the rotation of the particles and their acceleration at each revolution. The accelerated particles strike a target which is activated and produces radionuclides. Low and medium energy cyclotrons are primarily used in research and in the pharmaceutical industry to produce positron emitting isotopes, such as fluorine-18 or carbon-11. The radionuclides are then combined with molecules of varying complexity to form radiopharmaceuticals used in medical imaging. The best known of them is 18F-FDG (fluorodeoxyglucose marked by fluorine-18), which is an industrially manufactured injectable drug, commonly used for early diagnosis of certain cancers. Other radiopharmaceutical drugs manufactured from fluorine-18 have also been developed in recent years, such as 18F-Choline, 18F-Na, 18F-DOPA, along with other radiopharmaceuticals for exploring the brain. To a lesser extent, the other positron emitters that can be manufactured with a cyclotron of an equivalent energy range to that necessary for the production of fluorine-18 and carbon-11 are oxygen-15 and nitrogen-13. Their utilisation is however still limited due to their very short radioactive half-life. The approximate levels of activities involved for the fluorine-18 usually found in pharmaceutical facilities vary from 30 to 500 GBq per production batch. The positron emitting radionuclides produced for research purposes involve activities that are usually limited to a few tens of gigabecquerels. SIMPLIFIED DIAGRAM OF THE OPERATION OF A CYCLOTRON Semi-cylindrical D-shaped hollow electrodes Magnetic field generated by two electromagnets Progressively accelerated particles Electric field AC voltage generator Beam extraction channel Isotopes transferred and then used in shielded cells Target in which the isotopes are generated Source of electrically charged particles Electromagnet Semi-cylindrical hollow electrode ASN Report on the state of nuclear safety and radiation protection in France in 2021 257 08 – SOURCES OF IONISING RADIATION AND THEIR INDUSTRIAL, VETERINARY AND RESEARCH APPLICATIONS 08 07 13 04 10 06 12 14 03 09 05 11 02 AP 01
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