LES ACTIVITÉS NUCLÉAIRES : RAYONNEMENTS IONISANTS ET RISQUES POUR LA SANTÉ ET L’ENVIRONNEMENT One of the major challenges in the decommissioning of an installation is linked to the large volumes of waste produced, which are usually very much greater than the volumes produced during its operation. The decommissioning of the former facilities of the Alternative Energies and Atomic Energy Agency (CEA) and Orano’s first generation plants (in particular the plants which were involved in France’s deterrence policy, such as the gaseous diffusion facilities of the Pierrelatte Defence Basic Nuclear Installation (DBNI(1) – defence sector) in Tricastin, and the UP1 facility at the Marcoule DBNI, will thus lead to the production of a very large quantity of very low level (VLL) waste. The scale and the difficulty of the work must be assessed as early as possible in the life of the installation, and as of the design stage for new facilities, in order to ensure that they can be decommissioned safely within as short a time frame as possible. Furthermore, radioactive substances are still present in some old installations, sometimes in large quantities; these substances are not always readily accessible and some of them remain to be characterized. The conditions of retrieving and conditioning these substances in such cases constitute projects in their own right within the decommissioning projects. This is the case in particular with the former effluent treatment facilities of CEA and Orano (see chapter 13). Lastly, correct performance of the decommissioning operations is also dependent on the availability of the decommissioning support facilities (waste storage, processing and conditioning facilities, effluent treatment facilities) and of appropriate management routes for all the types of waste likely to be produced. When the final waste disposal outlets are likely not to be available at the time the decommissioning waste is produced, the licensees must prudently set up the facilities necessary for the safe interim storage of this waste pending opening of the corresponding disposal route. The adequacy of the available interim storage capacities for the waste resulting from BNI operation and decommissioning, and the progress of the studies concerning the various definitive radioactive waste management options, are regularly examined in this respect under the French National Radioactive Material and Waste Management Plan (PNGMDR) – see chapter 13). The question of management of the waste resulting from the decommissioning operations is addressed with particular attention during the assessment of the decommissioning and waste management strategies established by the CEA, EDF and Orano (see point 4 and Les cahiers de l’ASN #04). 1. Classification as a secret basic nuclear installation is decided by the Prime Minister on a proposal from the Minister for Defence when at least one of the facilities within the perimeter has the technical characteristics set by order of the Minister for Defence, is of interest to national defence and warrants special protection against nuclear proliferation, malicious intent or disclosure of classified information. 1.2 The ASNR decommissioning doctrine Many factors can influence the choice of one decommissioning strategy rather than another: national regulations, social and economic factors, financing of the operations, availability of waste disposal routes, decommissioning techniques and qualified personnel, knowledge of the operating history, exposure of the personnel and the public to ionising radiation resulting from the decommissioning operations, etc. 1.2.1 – Immediate dismantling The principle of decommissioning “in the shortest time frame possible under economically acceptable conditions” figures in the regulations applicable to BNIs (Order of 7 February 2012 setting the general rules relative to BNIs). This principle, which ASNR has affirmed since 2009 as regards BNI decommissioning and delicensing, has been enshrined in legislation by Act 2015-992 of 17 August 2015 relative to Energy Transition for Green Growth. This approach aims to avoid placing the technical and financial burden of decommissioning on future generations. It also provides the benefit of retaining the knowledge and skills of the personnel present during operation of the installation, which are vital during the first decommissioning operations. The regulatory framework in effect in France aims to ensure that: ∙The licensee prepares the decommissioning of its installation as of the design stage and updates this preparation throughout the life of the installation. ∙The licensee anticipates decommissioning and sends ASNR the decommissioning application file before it stops operating the installation. ∙The licensee has the financial resources to finance decommissioning, covering its anticipated expenses by dedicated assets. ∙The decommissioning operations are carried out in as short a time frame time frame as possible after shutting down the installation, a time which can nevertheless vary from a few years to a few decades, depending on the type of installation and the decommissioning complexity. The decommissioning plan, which describes the operations the licensee intends implementing to decommission its facility, aims to ensure optimal preparation and forward planning for decommissioning. Since 2007, this document has been required as from commissioning of the facility, and is then updated regularly during its lifetime. It capitalises on Operating Experience Feedback (OEF) by identifying any impacts on the future decommissioning operations, and must enable the licensee to justify the chosen decommissioning strategy on the basis of technical and economic criteria. 1.2.2 – Post operational clean-out and achieving the final state The decommissioning and Post-Operational Clean-Out (POCO) operations of a nuclear facility must lead to the gradual removal of the radioactive or hazardous substances from the structures and soils, with a view to delicensing the facility and its subsequent withdrawal from the list of BNIs. The radioactive substances can result from activation or deposition phenomena caused by the activities of the BNI or the incidents it has experienced. Hazardous chemical substances can also be present in the facility due to the use of certain processes or products (hydrocarbons, hydrofluoric acid, sodium, etc.). HIGHLIGHT No.1 Decommissioning: limiting false alarms from radiation protection monitors ASNR’s R&D aims to improve monitoring of decommissioning worksites by reducing false alarms at radiation protection monitors. The deployment of airborne radioactivity monitors (Continuous Air Monitors – CAMs) on decommissioning worksites for the radiation protection of workers has shown a recurrence of false alarms triggered by increased dust in the premises. These false alarms are mainly due to poor assessment of the contribution of radon daughter products, whose interaction with the artificial alpha measurement is strongly influenced by the sudden presence of a large quantity of particles. In this context, an R&D programme is currently being carried out to characterise the interactions between the ambient aerosols and the radioactivity, collected by a CAM, by combining aerosol models and nuclear simulations and using AI methods. This combination of approaches – theory, simulations and experiments – is helping to improve understanding of monitor behaviour in difficult situations, particularly at decommissioning worksites. ASNR Report on the state of nuclear safety and radiation protection in France in 2025 337 11 13 12 A / Z 10 09 08 01 05 02 06 03 07 04
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