The decommissioning phase may be preceded by a preparatory stage, provided for in the initial operating licence. This preparatory phase for example permits the removal of a portion of the radioactive and chemical substances (including the fuel of a nuclear reactor) as well as preparation for the decommissioning operations (readying of premises, preparation of worksites, training of teams, etc.). It is also during this preparatory phase that the installation characterisation operations can be carried out (radiological mapping, analysis of the operating history), which are vital for establishing the targeted POCO scenarios. The Environment Code requires – as is the case for all other BNIs – that the safety of a facility undergoing decommissioning be reviewed periodically and at least every ten years. ASN’s objective with these periodic safety reviews is to ascertain that the installation complies with the provisions of its Decommissioning Decree and the associated safety and radiation protection requirements through to its delicensing, by applying the principles of “Defence in Depth” specific to nuclear safety, with an approach that is proportionate to the risks. This is because, if the decommissioning operations result in a weakening, or even the disappearance of the existing physical barriers, the licensee must, depending on the residual safety and radiation exposure risks, maintain appropriate lines of defence necessary for the protection of workers and the environment (setting up of air locks, nuclear ventilation, radiation monitors, etc.). On completion of decommissioning, a nuclear facility can be delicensed by an ASN resolution approved by the Minister responsible for nuclear safety. It is then removed from the list of BNIs and is no longer subject to the BNI regulatory framework. Some twenty facilities, most of them old research reactors, have been decommissioned and delicensed to date. As at 31 December 2023, ASN was examining 23 decommissioning files for definitively shut down facilities whose decommissioning has not yet been prescribed or whose decommissioning conditions have substantially changed. 1.4 THE FINANCING OF DECOMMISSIONING AND RADIOACTIVE WASTE MANAGEMENT Articles L. 594-1 to L. 594-10 and D. 594‑1 to D. 594‑18 of the Environment Code define the system for ring-fencing funds to cover the costs of decommissioning nuclear facilities and managing the spent fuel and radioactive waste. This system is clarified by the Order of 21 March 2007 relative to ring-fencing of the funding of the nuclear costs. This Order aims to secure the financing of nuclear costs, following the “polluter-pays” principle. It is therefore up to the nuclear licensees to take charge of this financing by setting up a dedicated portfolio of assets capable of covering the expected costs. These costs must be evaluated conservatively, taking the various uncertainties into account. The licensees are thus obliged to submit three-yearly reports on these costs along with annual update notices to the Government. Provisioning is carried out under direct control of the State, which analyses the situation of the each licensee and can prescribe the necessary measures should it be found to be insufficient or inadequate. The General Directorate of the Treasury (DGT) and the General Directorate for Energy and the Climate (DGEC) constitute the administrative authority with competence for this control. The DGEC asks ASN to issue a technical opinion on the hypotheses adopted by the licensees. Whatever the case may be, the nuclear licensees remain responsible for the satisfactory financing of their long-term costs. 2 Situation of nuclear facilities undergoing decommissioning: specific challenges At the end of 2023, 36 nuclear facilities in France are definitively shut down or undergoing decommissioning, that is to say about a quarter of the BNIs (see map page 352). These facilities vary considerably (nuclear power reactors, research reactors, “fuel cycle” facilities, support installations, etc.), and the decommissioning challenges differ from one facility to the next. These risks are nevertheless all linked to the large quantity of waste to be managed during decommissioning and the need to carry out work very close to contaminated or activated zones. The risks for safety and radiation protection are all the higher if the facilities contain legacy waste; this is in particular the case with the Orano former spent fuel reprocessing plants and CEA’s old storage facilities. Furthermore, one of the major decommissioning problems is the loss of memory of the design and operation of the installation. Therefore maintaining skills and the installation characterisation phase to determine its initial state (state of the installation at the start of decommissioning) are of vital importance. 2.1 NUCLEAR POWER REACTORS 2.1.1 Pressurised water nuclear power reactors The decommissioning of Pressurized Water Reactors (PWRs) benefits from OEF from numerous projects around the world and the design of these reactors facilitates their decommissioning compared with other reactor technologies. The decommissioning of this type of installation presents no major technical challenges and its feasibility is guaranteed. Nevertheless, whatever the service life of the reactors in operation, EDF will be confronted with the simultaneous decommissioning of several PWRs. EDF will therefore have to organise itself to industrialise the decommissioning process in order to meet the requirement to decommission each installation in the shortest time possible. The first PWR decommissioning worksite in France is the Chooz A reactor (BNI 163). This is a small model compared with the nuclear power reactors in operation. It presents some specific technical difficulties due to its construction inside a cavern. This makes some operations more complex, such as the removal of large components like the steam generators. Decommissioning of the Chooz A reactor pressure vessel began in 2014 and is continuing satisfactorily. The Fessenheim Nuclear Power Plant (NPP) was finally shut down in 2020. These will be the first two 900 Megawatts electric (MWe) reactors to be decommissioned in France and are representative of the fleet of reactors currently operated by EDF. Decommissioning of the Fessenheim reactors will therefore also provide EDF with considerable experience feedback for its other PWRs (see “Regional overview” in the introduction of this report). 350 ASN Report on the state of nuclear safety and radiation protection in France in 2023 • 14 • Decommissioning of Basic Nuclear Installations
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