BNI 56 and the pits of BNI 72 and BNI 166. Retrieval of the waste from these facilities is complex and will span several decades. The waste must then be packaged and stored again in safe conditions. New packaging and storage facilities are thus projected or in the course of construction. The Effluent Treatment Stations (STEs) for their part have been shut down due to their ageing or because the facilities producing the effluents treated in these stations have stopped functioning. Examples include BNI 37-B at Cadarache and station STE2 of the La Hague plan (BNI 38). The difficulties associated with decommissioning of the effluent treatment stations are closely linked to their shutdown conditions, particularly the emptying and rinsing of their tanks. The decommissioning of these support facilities raises many issues. Firstly, poor knowledge of the operating history and the state of the facility to be decommissioned (taking account of the corrosion of waste drums or pollution of soils resulting from significant events that occurred when in service, for example) necessitates prior characterisation of the old stored waste and of the sludge or present in certain tanks. Moreover, taking into account the quantities, the physical and chemical forms and the radiotoxicity of the waste contained in these facilities, the licensee must develop means and skills that involve complex engineering techniques (radiation protection, chemistry, mechanics, electrochemistry, robotics, artificial intelligence, etc.). In effect, this waste is highly irradiating and heterogeneous, as it comprises structural elements from fuel reprocessing, technological waste, rubble, soils and sludge. Some of the waste has been stored in bulk with no prior sorting. The retrieval operations therefore require remotely operated pick-up means, conveyor systems, sorting systems, sludge pumping and waste packaging systems. The development of these means and carrying out the operations under conditions ensuring a satisfactory level of safety and radiation protection represent a major challenge for the licensee. Given that these operations can last several decades, the management of ageing of the facilities is also a challenge. 3. ASN actions related to facilities being decommissioned: a graded approach 3.1 The graded approach according to the risks of the facilities ASN ensures the oversight of facilities undergoing decommissioning, as it does for facilities in operation. The BNI System also applies to definitively shut down facilities. ASN implements an approach that is proportional to the extent of the risks or drawbacks inherent in the facility. The risks with facilities undergoing decommissioning differ from those for facilities in operation. For example, the risks of significant off-site discharges decrease as decommissioning progresses because the quantity of radioactive substances decreases. Consequently, the requirements relating to the control of risks and impacts are proportionate to the risks borne by the facilities. ASN thus considers that it is generally inappropriate to start significant reinforcement work on a facility undergoing decommissioning, on condition that the decommissioning operations reduce the sources of danger in the short term. 3.2 The periodic safety reviews of facilities undergoing decommissioning Given the diversity of the facilities and the situations in question, each periodic safety review necessitates an appropriate examination method. Some facilities undergoing decommissioning warrant particular attention owing to the risks they present and may be reviewed by the GPDEM. For others presenting a lower level of risk, the extent of the inspections and examinations is adapted accordingly. In 2022, ASN examined the periodic safety review reports of 17 facilities in final shutdown status. Inspections focusing on the periodic safety review were conducted in 2022 on four facilities undergoing decommissioning. These inspections are used to check the means implemented by the licensee to carry out its review, as well as compliance with the action plan resulting from its conclusions. They led to several requests for corrective action and additional information. In 2022, ASN rendered public its conclusions on the periodic safety review of the Solid Radioactive Waste Management Zone (ZGDSw BNI 72) and Chooz A (BNI 163). 3.3 Financing decommissioning: ASN’s opinion on the triennial reports The regulatory framework for ring-fencing the funds necessary for management of the long-term decommissioning and waste management expenses is presented in point 1.4. In 2022, ASN examined the licensees’ triennial reports of the accounts closed at the end of 2021. It published opinion CODEPCLG-061286 of 14 December 2022 and sent its observations to the Ministry responsible for energy. The next triennial reports will be submitted in 2025. More generally, ASN notes that the evaluation perimeter of the expenses considered in the majority of these reports must be supplemented because it does not take into account certain operations that could represent major financial issues, particularly the decommissioning preparation operations. Moreover, ASN considers that the initial states of the sites at the beginning of their decommissioning must be described more precisely, taking account of any pollution present in the soils and structures and evaluating the associated clean-out costs. In effect, the assumptions concerning the initial state of the sites are not sufficiently robust on the whole, whereas it is of fundamental importance to have sound knowledge of the state of the sites in order to evaluate the decommissioning expenses conservatively. Lastly, ASN underlines that the assumptions adopted for evaluating the complete costs must be reassessed in order to show reasonable caution in the scheduling of the decommissioning projects and programmes, taking account of the risks related to the unavailability of storage, treatment and disposal facilities. 350 ASN Report on the state of nuclear safety and radiation protection in France in 2022 • 13 • Decommissioning of Basic Nuclear Installations 13
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