LES CAHIERS DE L’ASN #04 DECOMMISSIONING CHALLENGES Ensuring the correct progress of this final phase in the life of a nuclear facility AUTORITÉ DE SÛRETÉ NUCLÉAIRE #04 • JUNE 2022 The decommissioning framework BNIs being decommissioned Informing the public

Contents THE DECOMMISSIONING FRAMEWORK • Decommissioning, a complex phase under surveillance 4 • What happens after final shutdown? 6 • What types of facilities and what are the stakes? 8 BNIs BEING DECOMMISSIONED • Nuclear installations definitively shut down 10 • Licensee decommissioning strategies assessed by ASN 12 • Close-up on a few BNIs undergoing decommissioning 16 • And elsewhere? 24 INFORMING THE PUBLIC • Your questions, our answers 26 GLOSSARY 30 2 • Les cahiers de l’ASN • June 2022

The lifetime of a basic nuclear installation (BNI*) comprises four main phases: design, construction, operation and decommissioning. ASN intervenes at each of these phases. It issues an opinion on the draft creation authorisation or decommissioning decrees for the installations, and regulates operation by means of binding requirements. Decommissioning concerns removal of radioactive substances and waste, equipment disassembly operations, and clean-out of structures and soils. Responsibility for this lies with the site licensees. In France, decommissioning of a BNI* is governed by regulations based on the principle of dismantling as rapidly as possible and in economically acceptable conditions. The decommissioning process concerns a large number of installations in France. It comprises technical challenges regarding the safety, environmental or radiation protection aspects. It can take one or more decades. Shall we start decommissioning? Yes, it’s safe! * See glossary page 30 Decommissioning challenges • 3

The regulatory framework: work as rapidly and as effectively as possible... Decommissioning, a complex phase under surveillance The decommissioning of a BNI* is regulated by the Environment Code and the Order of 7 February 2012 “setting the general rules relative to BNIs*”. It is based on two key objectives: “Work rapidly” so that future generations do not bear the burden of decommissioning, while benefiting from the knowledge and skills of the teams present during the operation of the installation; “Work effectively”, means gradually removing the radioactive or dangerous substances from the structures and soil, with a view to the delicensing* of the installation. Clean-out will be taken as far as reasonably achievable. • With regard to “Work rapidly”, decommissioning operations are often lengthy and costly. They represent a real challenge for the licensee. The licensee must be able to draw on the installation’s operating history, in particular the know-how and knowledge of the personnel teams present during its operation. Since 2015, the strategy adopted in France aims for the following: ∙ the licensee makes provision for the decommissioning of its installation as of the design stage; ∙ the time between final shutdown of the installation and the first decommissioning operations is as short as possible. • With regard to “work effectively”, ASN asks that the licensees study a complete clean-out scenario. This scenario aims to guarantee lasting, long-term protection for people and the environment. If, owing to the nature of the contamination, it were to prove difficult to apply this approach, ASN considers that the licensee must go as far as reasonably possible in the site clean-out process. Similarly, in accordance with the general radiation protection principles, the dosimetric impact of the site after delicensing* shall be As Low As Reasonably Achievable (ALARA principle). ASN is not in favour of introducing general thresholds and considers that it is preferable to adopt a case-by-case approach according to the intended subsequent use of the site once cleaned-out. The final shutdown of a BNI* marks the beginning of a phase that is often lengthy, and comprises new and changing risks. ASN conducts its oversight in accordance with the Decrees setting out the main steps in decommissioning, the date of completion of decommissioning and the final state to be attained. * See glossary page 30 DECOMMISSIONING FILE SUBMISSION 4 • Les cahiers de l’ASN • June 2022 THE DECOMMISSIONING FRAMEWORK

Once a BNI* is definitively shut down, it must be decommissioned. The decommissioning of a BNI* is prescribed by a Decree, issued after consulting ASN. A decommissioning file describes all the envisaged work and, for each step, explains the nature and scope of the risks presented by the facility, as well as the means used to manage them. This file is the subject of a public inquiry among the local residents, associations and competent administrative authorities. On the basis of the file, the decommissioning decree specifies the main steps in decommissioning, its completion date and the final state to be attained. In addition, the Environment Code requires that the safety of a facility being decommissioned, in the same way as that of all the other BNIs*, must undergo a periodic safety review. This periodic safety review shall take place every 10 years. ASN ensures that the installation complies with the provisions of its decommissioning decree and the safety and radiation protection requirements through to its delicensing*. These requirements are consistent with an approach that is proportionate to the safety implications of the installation. On completion of decommissioning, a BNI* 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 governed by this system. In support of its delicencing* application, the licensee must notably provide a file containing a description of the state of the site after decommissioning (analysis of the state of the soils, remaining buildings or equipment, etc.) and demonstrating that the planned final state has indeed been reached. Depending on the final state reached, ASN may require the implementation of active institutional controls* as a condition of delicensing*. These may set a number of restrictions on the use of the site and buildings – as is the case on certain industrial sites (limited to industrial use only for example) - or precautionary measures (radiological measurements to be taken in the event of excavation*, etc.). WHO PROVIDES THE FINANCING? The Environment Code defines the system for securing the funds to meet the nuclear costs for the decommissioning of nuclear installations, and managing the spent fuel and the radioactive waste. The financing of decommissioning is inspired by the “polluter-pays” principle. As of the creation of the installation, the nuclear licensees are required to cover the cost of this financing, taking care to make provision for the funds needed for its decommissioning. They are obliged to submit triennial reports on these costs and annual update notices to the Government. Provisioning is carried out under direct control of the State, which analyses the situation of each licensee and can prescribe the necessary measures should it be found to be insufficient or inadequate. In any case, the nuclear licensees remain responsible for the satisfactory financing of the decommissioning costs. ...in compliance with a rigorous process Decommissioning challenges • 5

As of the date of final shutdown, the licensee is no longer authorised to operate its installation. It begins to prepare for its decommissioning. The operations in preparation for decommissioning often consist in removing the radioactive and chemical substances present in the installation (spent fuel), in preparing the premises (organisation of storage areas), or adapting the utility networks (ventilation, electricity distribution). At least 2 years before the date envisaged for final shutdown, the licensee informs the Minister responsible for nuclear safety, and ASN, of its intention to definitively shut down its installation. This declaration is made known to the public. No later than 2 years after the shutdown declaration, the licensee must send the Minister its decommissioning file. This file presents the decommissioning operations proposed by the licensee, as well as the steps it takes to mitigate the impacts on persons and the environment. Once a BNI* has been definitively shut down, it must be decommissioned. France has opted for “immediate” dismantling. A regulatory procedure is implemented to oversee decommissioning of the installation up to its delicensing*. What happens after final shutdown? Preparation for decommissioning End of operation Transmission of decommissioning file 2 years maximum Final shutdown Shutdown declaration * Voir glossaire page 30 NPP SHUT DOWN See glos ary page 30 6 • Les cahiers de l’ASN • June 2022 THE DECOMMISSIONING FRAMEWORK

On the basis of the decommissioning file submitted by the licensee, the Minister issues a Decree stipulating the decommissioning operations to be performed on the installation, along with the duration of decommissioning. In a resolution, ASN may also issue technical requirements to further regulate decommissioning. Decommissioning concerns all the technical operations carried out with a view to achieving a final state that makes delicensing* of the installation possible. It concerns the electromechanical decommissioning and clean-out of soils and structures. From the legal viewpoint, the “decommissioning operations” only begin once the Decommissioning Decree has entered into force. Between final shutdown of the installation and this moment of entry into force, the licensee carries out “operations in preparation for decommissioning”. In this document, for reasons of simplification, all the operations performed after final shutdown are defined as “decommissioning operations”. Delicensing* consists in removing an installation from the BNI* list, which implies that the installation is no longer subject to the BNI* legal and administrative system. Delicensing* takes place at the end of the decommissioning operations, on the basis of a file presenting the final state of the installation. Usage restrictions may be implemented if necessary, if some of the pollution could not be removed. In this case, the State’s decentralised departments are responsible for ensuring compliance with these restrictions. Decommissioning Delicensing* Decommissioning Decree Decommissioning operations Delicensing resolution* ASN’s oversight duties cease. DÉCI DÉCI DÉCI DÉC DECISION Decommissioning challenges • 7

What types of facilities and what stakes? With the exception of pressurised water reactors (PWR) in NPPs, which are all designed using the same model, most BNIs* undergoing decommissioning represent a variety of technologies, uses and past histories which often complicate the decommissioning operations. There is significant operating experience feedback for decommissioning of research reactors, owing to the decommissioning of numerous similar installations in France, notably on CEA’s Grenoble site. During the course of decommissioning, the radioactivity risks rapidly give way to conventional industrial risks, for example the chemical risk during the clean-out phase, or that linked to the management of several simultaneous worksites. Pressurised water reactors After decommissioning of the Chooz A reactor (Ardennes département**), which began in 2007, decommissioning started on the two reactors of the Fessenheim NPP (Haut-Rhin département), which was shut down in 2020. There is considerable operating experience feedback from PWR decommissioning: 42 PWRs are being decommissioned worldwide in 2021. There are no major technical difficulties in the decommissioning of these installations, which takes about twenty years. Other reactors In France, several NPP reactors undergoing decommissioning were based on technologies no longer in use: gas-cooled reactors (GCRs – located in Bugey, Chinon and Saint-Laurent-des-Eaux), heavy water reactor (Brennilis), fast breeder reactors (Phénix and Superphénix). For these reactors, some of which have not been operating for several decades, there is no significant operating experience feedback, unlike with the PWRs. The fact that they are unique means that specific and often complex decommissioning operations must be designed, such as specific remote-operated systems. NUCLEAR POWER REACTORS Different reactor technologies have been used to produce electricity in France. Their decommissioning must take account of their specific characteristics. As of the final shutdown of these reactors, removal of the fuel is a means of achieving a 99% reduction in the radioactivity present in the installation. RESEARCH REACTORS These are characterised by a far lower power level than nuclear power reactors (from 100 Watts thermal – Wth – to 70 Megawatts thermal – MWth). Nine experimental reactors, operated by CEA, are currently definitively shut down; when they were designed back in the 1960s to 1980s, the question of their decommissioning was not considered. * See glossary page 30 ** Administrative region headed by a Prefect. 8 • Les cahiers de l’ASN • June 2022 THE DECOMMISSIONING FRAMEWORK

FUEL PRODUCTION Two installations designed and used to fabricate nuclear fuel are being decommissioned on the Tricastin site (Drôme département): one specialised in the conversion* of uranium (Comurhex), the other in the enrichment* of uranium by gaseous diffusion (Eurodif). The operating history of these old installations is not fully known; determining the pollution present in the soils beneath the structures therefore remains an important issue. Furthermore, the industrial processes used at the time involved large quantities of toxic chemical substances (uranium, chlorine trifluoride and hydrogen fluoride, for example): the containment of these chemical substances is also an issue, as are the risks related to internal contamination of the workers. SUPPORT INSTALLATIONS “Support installations” are certain installations intended for the storage and processing of radioactive effluents and waste. Most of them were commissioned in the 1960s and are located at Cadarache, Fontenay-aux-Roses, La Hague and Saint-Laurent-des-Eaux. These installations were not initially designed to allow the removal of their waste, and in some cases they were seen as being the definitive waste disposal site. Retrieval of the waste from these facilities is all the more complex and will span several decades. The decommissioning operations must take account of severe corrosion and soil pollution phenomena, caused by ageing of the installations and events which occurred during their operation. These difficulties are compounded by incomplete knowledge of the operating history and the state of the installation to be decommissioned. Of these installations, the UP2-400 plant, the first reprocessing plant for the fuel from the first generation reactors (GCRs) is being decommissioned. It contains highly irradiating waste, such as technological waste, rubble, earths and sludges, sometimes stored loose, without preliminary sorting. Decommissioning is thus carried out in parallel with WRC* operations, which require the implementation of complex, unique engineering processes. FUEL REPROCESSING AND WASTE MANAGEMENT This concerns the spent fuel and waste storage and reprocessing installations, located on the La Hague site and operated by Orano. Their decommissioning usually entails prior retrieval and conditioning of legacy nuclear waste (WRC*). Owing to the incomplete record of their history, the waste inventory and radiological status of these installation are hard to establish. The laboratories are faced with the problem of management of the waste stored on the site at a time when the storage or disposal solutions had not yet been put into place. LABORATORIES These installations, which date from the 1960s, were devoted to research, in order to support an emerging nuclear power industry. Four civil laboratories have so far been definitively shut down in France. Decommissioning challenges • 9

CADARACHE MARCOULE TRICASTIN BUGEY FONTENAY-AUX-ROSES CHOOZ SACLAY SAINT-LAURENT- DES-EAUX CREYS-MALVILLE GRENOBLE FESSENHEIM CHINON BRENNILIS LA HAGUE Nuclear installations definitively shut down At the end of 2021, 35 installations had been definitively shut down in France, with 23 of them undergoing decommissioning. * See glossary page 30 MANUFACTURE, TRANSFORMATION OR STORAGE OF RADIOACTIVE SUBSTANCES BNI 32 • Plutonium technology facility (ATPu) Commissioned: 1962 Being decommissioned BNI 52 • Enriched uranium processing facility (ATUe) Commissioned: 1963 Being decommissioned BNI 37-B • Effluent Treatment Station (STE) Commissioned: 2015 (1) Final shutdown BNI 53 • Central fissile material warehouse (MCMF) Commissioned: 1966 Final shutdown BNI 54 • Chemical Purification Laboratory (LPC) Commissioned: 1966 Being decommissioned BRENNILIS – EDF REACTOR BNI 162 • EL4-D Commissioned: 1967 Being decommissioned BUGEY – EDF REACTOR BNI 45 • Bugey 1 Commissioned: 1972 Being decommissioned CADARACHE – CEA REACTORS BNI 25 • Rapsodie Commissioned: 1967 Being decommissioned BNI 39 • Masurca Commissioned: 1966 Final shutdown BNI 42 • ÉOLE Commissioned: 1965 Final shutdown BNI 92 • Phébus Commissioned: 1978 Final shutdown BNI 95 • Minerve Commissioned: 1977 Final shutdown 10 • Les cahiers de l’ASN • June 2022 BNIs BEING DECOMMISSIONED

Key Reactor Plant Laboratory and research reactor GRENOBLE – CEA TRANSFORMATION OF RADIOACTIVE SUBSTANCES BNI 36 • Radioactive effluent and solid waste treatment station (STED) Commissioned: 1964 Being decommissioned BNI 79 • High-level waste storage unit Commissioned: 1972 Being decommissioned LA HAGUE – Orano Recyclage TRANSFORMATION OF RADIOACTIVE SUBSTANCES BNI 33 • Spent fuel reprocessing plant (UP2-400) Commissioned: 1964 Being decommissioned BNI 38 • Radioactive effluent and solid waste treatment station (STE2) Commissioned: 1964 Being decommissioned BNI 47 • ELAN IIB Unit Commissioned: 1970 Being decommissioned BNI 80 • Oxide High Activity facility (HAO) Commissioned: 1974 Being decommissioned MARCOULE – CEA REACTOR BNI 71 • Phénix Commissioned: 1973 Being decommissioned SACLAY – CEA RESEARCH REACTORS BNI 18 • Ulysse Commissioned: 1961 Being decommissioned BNI 40 • Osiris and Isis Commissioned: 1966 Final shutdown BNI 101 • Orphée Commissioned: 1980 Final shutdown UTILISATION OF RADIOACTIVE SUBSTANCES BNI 49 • High activity laboratory (LHA) Commissioned: 1954 Being decommissioned CHINON – EDF UTILISATION OF RADIOACTIVE SUBSTANCES BNI 94 • Irradiated Materials Facility (AMI) Commissioned: 1964 Being decommissioned REACTORS BNI 133 – BNI 153 – BNI 161 Chinon A1D – A2D – A3D Commissioned: 1963 – 1965 – 1966 A1D et A2D : Final shutdown A3D : Being decommissioned CHOOZ – EDF REACTOR BNI 163 • Chooz A Commissioned: 1967 Being decommissioned CREYS-MALVILLE – EDF REACTOR BNI 91 • Superphénix Commissioned: 1985 Being decommissioned FESSENHEIM – EDF REACTORS BNI 75 • Fessenheim 1 – 2 Commissioned: 1977 Final shutdown FONTENAY-AUX-ROSES – CEA RESEARCH FACILITY BNI 165 • Procédé Commissioned: 2006 (2) Being decommissioned EFFLUENT REPROCESSING AND WASTE STORAGE FACILITY BNI 166 • Support Commissioned: 2006 (2) Being decommissioned SAINT-LAURENT-DES-EAUX – EDF REACTORS BNI 46 • Saint-Laurent A1 – A2 Commissioned: 1969 and 1971 Being decommissioned TRICASTIN – Orano Chimie enrichissement TRANSFORMATION OF RADIOACTIVE SUBSTANCES BNI 105 • Comurhex uranium hexafluoride* preparation plant Commissioned: 1978 Being decommissioned BNI 93 • Georges Besse plant for separating uranium isotopes by gaseous diffusion Commissioned: 1979 Being decommissioned 1. This date is because of the separation of BNI 37 (commissioned in 1964) into two BNIs : 37-A and 37-B. 2. This date is because of the merging of former BNIs, commissioned in 1966 and 1968. For more information, scan this QR code. Decommissioning challenges • 11

With the final shutdown of a large number of installations in recent years, the major nuclear licensees are faced with having to carry out several decommissioning projects at the same time. To obtain an overview of these various projects and how they interface with each other, ASN examines the licensees’ decommissioning and waste and materials management strategies. EDF is the licensee of the French nuclear fleet, consisting of 56 PWR reactors in operation in 18 NPPs and it also has to manage the decommissioning a dozen installations. The gas-cooled reactor (GCR) decommissioning strategy EDF’s first generation of nuclear reactors are of the GCR type, operating with natural uranium. The first GCR reactor was commissioned at Chinon (Indre-et-Loire département) in 1963. A total of six reactors of this type were built in France. These reactors were shut down between 1973 and 1994, when this technology was abandoned. The fuel, which accounted for the vast majority of the risk to the safety of these installations, has been removed. However, some of these installations were only partially decommissioned before being placed under surveillance, pending final dismantling. The pertinence of “immediate” dismantling of nuclear installations was in fact only recognised by all players in the early 2000s. An initial scenario studied by EDF consisted in filling the reactor core with water so that the decommissioning operations could be carried out, thus mitigating the radioactivity risks. EDF originally planned to complete decommissioning of these reactors between 2024 and 2031. Given the major technical difficulties (tightness of the reactor vessel and treatment of the contaminated water), but also technological progress which has identified other solutions, remote-operation in particular, EDF in 2016 Licensee decommissioning strategies assessed by ASN Decommissioning strategies appropriate to the reactor model and changing technologies * See glossary page 30 12 • Les cahiers de l’ASN • June 2022 BNIs BEING DECOMMISSIONED

announced that the “under water*” dismantling scenario was no longer the reference solution, resulting in a change in strategy. EDF thus opted for an “in air*” dismantling scenario, eliminating the problems linked to the use of water. This change entailed a significant postponement in the dismantling operations. EDF decided to use an industrial demonstrator to validate certain complex operations, followed by complete dismantling of one reactor vessel before beginning dismantling of the other five vessels. EDF has also significantly increased the time needed to decommission a reactor. The PWR decommissioning strategy The current French NPP fleet consists entirely of PWRs. They operate with enriched uranium. Considerable experience feedback from the decommissioning of these reactors has been acquired through numerous projects internationally: 42 reactors of this type are currently undergoing decommissioning around the world, and 6 have already been decommissioned in the United States. There are thus no major technical issues regarding the feasibility of the decommissioning operations which, according to international experience feedback, last about twenty years. They start following the issue of the decommissioning decree, which sets out the main steps: in the reactor building, removal of the primary system after any necessary decontamination, followed by cutting of the reactor pressure vessel. The systems of the other buildings of the nuclear island are also decontaminated at the same time. After removing all dismantled equipment and waste, the licensee continues with clean-out of the various buildings and then their demolition, with a view to delicensing* of the BNI* and remediation of the site. In France, the first decommissioning decree for a PWR concerned the Chooz A reactor, installed in a cavern in the Ardennes mountains, in 2007. The next one will concern the Fessenheim NPP. ASN’S POSITION • For the GCRs, ASN duly notes the difficulties being encountered for continued decommissioning “under water*” and considers the scenario change to be acceptable. It will examine the safety of the operations to be carried out “in air*” and the corresponding time-frames. In resolutions of March 2020, and following public consultation, ASN instructed EDF to submit an application file for modification of the existing decommissioning decrees for the Bugey 1, Saint-Laurent A1 and A2 and Chinon A3 reactors, and to submit the decommissioning files for those reactors as yet not covered by one (Chinon A1 and Chinon A2), no later than the end of 2022. ASN also indicated that EDF will need to shorten the decommissioning time-frames set out in its strategy, in order to meet the legislative obligation for decommissioning in a period as short as possible for each reactor. Finally, in order to make the reactor decommissioning schedule more reliable, ASN asks EDF to identify adequate waste management routes which could, if necessary, lead to the creation of new waste storage facilities. • For the PWRS, whatever the service life of the reactors currently in operation, EDF will be faced with the simultaneous decommissioning of several PWRs in the coming years. 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. Decommissioning of the Fessenheim NPP will provide useful industrial feedback in this respect. For more information, scan this QR code. Decommissioning challenges • 13

are high. These operations must be based on characterisation of the waste and qualification of the processes envisaged, for which the licensee must reinforce its methods to confirm the feasibility of the envisaged solutions. The WRC* worksites are of particular importance, given the inventory of radioactive substances present and the age of the facilities in which they are stored, which do not meet current safety standards. WRC* projects are becoming increasingly complex owing to the interactions with the plants in operation on the site. Some work could span a period of several decades. In addition, Orano does not systematically envisage demolishing the structure of the facilities: some of them will continue to be used for industrial purposes (equipment storage, etc.). In order to achieve the target final state, clean-out of the structures and soils is Orano’s reference option. However, the licensee does not rule out a two-stage operation, in order to meet the need for temporary use of all or part of the facility. The decommissioning and WRC* operations will generate a large quantity of waste, for which there is no disposal route. When disposal routes are not yet available, the management solution adopted by Orano is interim storage. In order to deal with a high level of industrial complexity, a strategy which envisages reusing certain structures ASN’S POSITION In 2016, Orano transmitted its decommissioning and waste management strategy for the La Hague and Tricastin sites. After reviewing these aspects, which led to a cycle of discussions with Orano, ASN notes progress in the assimilation of the immediate dismantling objectives, progress in the decommissioning operations on several facilities at Tricastin and the definition of conditioning processes for radioactive waste from the La Hague site. ASN nonetheless asked it to improve the following four aspects of its strategy: • decommissioning and waste management must be prioritised according to the risks and Orano must design new reprocessing, conditioning, storage and transport capacity for effluents and waste, in order to replace certain ageing equipment and increase storage capacity; • implementation of the clean-out strategy must be based on sufficient knowledge of the current state of the facilities and more particularly the civil engineering structures and soils. It also ensures that clean-out is taken as far as reasonably achievable if complete clean-out is not possible for technical or economic reasons; • WRC* must be better managed: the issue is to characterise the waste and qualify processes so that it can be retrieved and conditioned in order to reduce the risks from its radioactivity as early as possible; • the oversight of complex projects* must be improved: Orano must analyse the causes of delays to the priority projects and ensure the adequacy of the resources devoted to these projects so that it can submit detailed 5-year activity schedules to ASN, presenting the key milestones. * See glossary page 30 In the future, Orano will have to conduct several large-scale decommissioning projects: that of the first generation fuel reprocessing plant at La Hague (UP2-400 and its support units), as well as that of the uranium conversion* and enrichment* plants at Tricastin. The licensee adopts the principle of immediate dismantling; it must carry out certain particularly complex operations, notably those linked to WRC*, for which the safety and radiation protection stakes For more information, scan this QR code. 14 • Les cahiers de l’ASN • June 2022 BNIs BEING DECOMMISSIONED

In France, nearly 40 CEA civil and defence nuclear facilities have been finally shut down or are being decommissioned. The ageing and varied design of these facilities did not take account either of decommissioning or of radioactive waste management in accordance with current safety requirements. Given the number and complexity of the operations to be carried out, CEA defined priorities, based primarily on an analysis of the potential hazards, in order to mitigate the risks presented by these facilities. The highest-priority operations concern certain individual facilities on the defence basic nuclear installation (DBNI) in Marcoule (Gard département), as well as on the BNIs* in Saclay (Essonne département) and Cadarache (Bouches-du-Rhône département). An accident in one of these facilities could lead to significant nuclear safety and radiation protection consequences. With regard to the lower priority facilities, CEA is moving towards a “two-stage” decommissioning of each facility. First of all, most of the dispersible radiological inventory* will be removed. Secondly, following a potentially lengthy period of interruption, the operations will be completed. The resulting surveillance, upkeep and operations needed to maintain a sufficient level of safety in these facilities, for a period of decades up until delicensing*, will significantly increase the final cost of the decommissioning of all the CEA facilities. Moreover, the priority decommissioning of facilities with significant safety implications will lead to the modification of the regulatory requirements already issued for those facilities for which decommissioning is postponed. A strategy that ranks the priorities according to the risks, taking account of limited resources ASN’S POSITION • In their joint opinion of 27 May 2019, ASN and the Defence Nuclear Safety Authority (ASND) confirmed the overall pertinence of the prioritisation proposed by CEA, taking account of the resources allocated by the State and the large number of nuclear facilities being decommissioned, which implies massive investment. • ASN and ASND have concerns regarding the human and financial resources that are planned in order to address all the situations with safety implications or the most significant environmental harmful effects in the coming 10 years. A specific investment effort, as well as the creation of engineering units and the reinforcement of the safety teams dedicated to these projects, would seem to be necessary. • If these projects are to progress, the licensee’s oversight capabilities will have to be reinforced, allied with rigorous and transparent State monitoring of CEA’s actions, in terms ofcost, time and effectiveness. • The public must be regularly informed of the progress of the programme as a whole. For more information, scan this QR code. Decommissioning challenges • 15

A close look at a few BNIs undergoing decommissioning The installations vary widely and the decommissioning constraints may differ from one BNI* to another. Installation: 70 MWe CO2-cooled heavy water reactor in Brennilis (Finistère département) Licensees: CEA, then EDF Commissioned: 1967 Final shutdown: 1985 Decommissioning phases n  The fuel is removed, and decommissioning is completed for the buildings “outside the reactor block” (exchangers, effluent treatment station, waste hangar, etc.). n  Since 2018, a new file has been under review for management of the reactor block decommissioning operations. n  End of decommissioning envisaged by EDF: in the 2040s. Decommissioning challenges Decommissioning of this unique reactor in a confined space, which notably requires the use of remote-operated resources. Brennilis Installation: two 500 MWe GCR type reactors in Saint-Laurent-Nouan (Loir-et-Cher département) Licensee: EDF Commissioned: 1969 and 1971 Final shutdown: 1990 and 1992 Decommissioning phases n  The fuel is removed and some of the equipment “outside the reactor vessel” is being dismantled (spent fuel pool, etc.). n  Dismantling, initially planned to be “under water*” will now be performed “in air*”. n  New decommissioning file planned for the end of 2022. n  End of decommissioning envisaged by EDF: end of the century. Decommissioning challenges The licensee must ensure that management solutions are available for the graphite components and reduce the overall decommissioning time-frame. Saint-Laurent A * See glossary page 30 16 • Les cahiers de l’ASN • June 2022 BNIs BEING DECOMMISSIONED

Installation: two 900 MWe PWRs (Haut-Rhin département) Licensee: EDF Commissioned: 1977 and 1978 Final shutdown: 2020 Decommissioning phases n  The spent fuel from reactor 1 was completely removed in 2021; removal of the spent fuel from reactor 2 should be completed in 2023. n  In 2022, ASN continues to review the decommissioning file transmitted by EDF and will notably call on its technical support organisations for their analysis of the file: the Institute for Radiation Protection and Nuclear Safety (IRSN) and the Advisory Committee of Experts for Decommissioning (GPDEM). n  The licensee is currently performing a certain number of operations in preparation for decommissioning: drainage and decontamination of systems, removal of waste and chemical products, preparation of spaces for processing of future waste from decommissioning, collection of spares for other sites, etc. n  End of decommissioning envisaged by EDF: end of the 2040s. Decommissioning challenges Once the fuel has been removed, the main decommissioning challenges lie in managing a large-scale worksite with a radiological dimension: worker radiation protection, worksite safety, waste management consistent with the conditioning, storage and disposal facilities, etc., without forgetting project management, and building on experience that is as exemplary as possible with a view to future decommissioning projects on other reactors. Fessenheim Chooz A Installation: first PWR operated in France, with a power of about 300 MWe (Ardennes département) Licensee: EDF Commissioned: 1967 Final shutdown: 1991 Decommissioning phases n  Installations partially located in underground caverns. n  The fuel has been removed, the systems have been drained, the turbine hall, the pumping station and the outside buildings have been demolished; the decontamination and removal operations for the steam generators and primary system components (except for the pressure vessel) have already been carried out. The spent fuel pool and all the auxiliary systems have to a large extent been dismantled. In 2021, dismantling work on the “reactor pressure vessel internals” was completed. n  Next step: with a view to dismantling of the reactor pressure vessel, installation of an evaporator to treat the cavity water before discharge (currently in progress). Operation scheduled to start in the first quarter of 2022. Decommissioning challenges The main challenge of this decommissioning is to manage radiation protection, in particular the risk of contamination of the workers by alpha particles*. Decommissioning challenges • 17

* See glossary page 30 Installation: the UP2-400 plant consists of four BNIs* operated on the La Hague site (Manche département). The installations were intended for reprocessing of certain reactor fuels (those from the GCR reactors for example – BNI 33), the treatment of effluents and the storage of waste and residues from the activities of the various units (BNI 38), the manufacture of sealed radioactive sources* (BNI 47) or the reprocessing of light water reactor fuels (BNI 80). The units, consisting of cells, silos and pools, contain large quantities of waste and residues from the activities of UP2-400: sludges and resins, equipment (mixers-decanters, vessel, etc.), residues of chemical products used to process waste, etc. Licensee: Orano Commissioned: 1964 (except for BNI 47 and BNI 80, which were commissioned in 1970 and 1974 respectively) Final shutdown: 2004 (1973 for BNI 47) UP2-400 La Hague Decommissioning phases n  For BNI 33, the decommissioning operations in the main units consist in dismantling numerous rooms, as well as the numerous shielded cells, vessels, pipes, gloveboxes, used in the process. The retrieval and conditioning of ion exchange resins used to filter the spent fuel pool water also need to be completed. n  For BNI 80, the decommissioning operations consist primarily in collecting the waste stored in the pool and in a silo, by means of a special shielded cell, which will be commissioned in a few years. The fuel stored in the pools of the HAO/Nord unit has been removed. n  For BNI 47, the decommissioning operations consist in completing the removal of the last process equipment, followed by the clean-out operations. n  For BNI 38, the current decommissioning operations are focusing on the retrieval and removal of legacy radioactive waste, notably solid waste and sludges stored loose in silos. Decommissioning challenges Taken together, the four BNIs* constitute an industrial complex housing about ten main units, thousands of rooms each containing numerous items of process equipment (shielded cells, silos, vessels, gloveboxes, pools, etc.) in which highly radioactive and chemical substances were handled. The WRC* operations are a preliminary to the decommissioning and clean-out operations and will span several decades. They require the performance of additional work to characterise the waste, implement new equipment based on remote-operated systems, and to develop specific retrieval and conditioning processes, some of which are still at the design stage. 18 • Les cahiers de l’ASN • June 2022 BNIs BEING DECOMMISSIONED

Installation: BNI 56 consists of a range of storage facilities for the radioactive waste produced on the Cadarache site (Bouches-du-Rhône département): pits (6), pools (3), trenches (5) and hangars (11). Licensee: CEA Commissioned: 1965 Final shutdown: scheduled for 2023 Decommissioning phases With a view to decommissioning, the preparation operations have started. n  The retrieval and removal of waste from the pools are complete and the pools are being cleaned-out. n  Trench T2 has been emptied of the waste it contained. The scenario for waste recovery from the other trenches (T1, T3, T4 and T5) is being defined; it will be based on the lessons learned with trench T2, for which the operations were seriously slowed down by difficulties relating in particular to the uncertainties regarding the physical condition and the radiological inventory* of the waste packages. n  At present, the decommissioning operations focus on the retrieval and removal of “intermediate level” radioactive waste from the recent pits, as the “low level” waste has already been removed. n  The retrieval, removal and conditioning of the waste from the old pits should complete the decommissioning operations on BNI 56. They will notably require the construction of appropriate buildings for handling and conditioning this highly radioactive waste. Decommissioning challenges These relate to the retrieval and conditioning of legacy waste from an installation which, until 1983, was designed to act as its final disposal location. This bulk waste represents a significant dispersible radiological inventory*. The storage conditions led to considerable soil pollution. Clean-out is also a major challenge. Storage yard Cadarache Installation: the Georges Besse 1 plant (or “Eurodif”) was intended for the enrichment* of natural uranium by a gaseous diffusion process, for subsequent use in the nuclear power reactors (Drôme département). On the Tricastin site, the four plants constitute BNI 93, covering a total surface area of 190,000 m2. Licensee: Orano Commissioned: 1978 Final shutdown: 2012 Decommissioning phases n  Scheduled time-frame for complete decommissioning of the installation: 15 years after the study phase. n  Rinsing of diffuser cascades* during the work in preparation for decommissioning (reduction in the quantity of uranium). n As of 2024: demolition of the two cooling towers. n  Studies are in progress to design the future equipment for cutting and conditioning the diffuser cascades*. Decommissioning challenges The decommissioning challenges will first of all concern the diffusers, notably their disassembly, cutting and compacting of massive parts. These operations will require the use of specific tools and the operation of new units. The licensee will be required to ensure that the waste is shipped to the final disposal route (on average about 8,000 m3/year). The decommissioning of Eurodif could generate 130,000 tons of very-low level (VLL) metal waste that could potentially be recycled. Eurodif Tricastin Decommissioning challenges • 19

High activity laboratory Saclay Installation: 18 laboratories (called “cells”) make up the High Activity Laboratory (LHA) on the Saclay site (Essonne département). Performance of research work or production of various radionuclides. Licensee: CEA Commissioned: 1954 Final shutdown: 1996 Decommissioning phases n  Decommissioning of the laboratories has been authorised since 2008. n  The licensee has removed radioactive processes and equipment present in all the cells (except for the shielded line* in cell 10). Some cells have been completely cleaned-out and downgraded. n  In 2022, ASN will review the file applying for a modification of the decommissioning decree. This file was submitted by the LHA licensee following the 2017 discovery of significant soil pollution between certain cells. n  CEA envisages completing the decommissioning and clean-out operations by the 2040 time-frame. n  Three laboratories still in operation should remain, but under the installations classified for protection of the environment (ICPEs*) system. After clean-out, some cells will be kept for the storage of certain equipment and drums of intermediate level, long‑lived waste (ILW-LL). Decommissioning challenges The licensee must clean-out the soils to depths ranging from 1 to 10 m, under containment, with excavations close to the cells, but without destabilising their foundations. * See glossary page 30 20 • Les cahiers de l’ASN • June 2022 BNIs BEING DECOMMISSIONED

AM7 AM3 M61 A21 Ulysse Saclay Installation: Ulysse low-power research reactor (100 kilowatts thermal – kWth), used for teaching and experimentation activities, in Saclay (Essonne département) Licensee: CEA Commissioned: 1961 Final shutdown: 2007 Start of decommissioning: 2014 Decommissioning completed: August 2019 Decommissioning phases n  The fuel has been removed and the clean-out operations were completed in 2019, supplemented by radiological cleanness checks on the buildings and soils. n After the decommissioning operations, the installation’s building was kept and comprises no areas with any irradiation or contamination risk. DECOMMISSIONING WORK After 5 years of work, decommissioning of the Ulysse nuclear reactor was completed in 2019. The work was done on-time. Decommissioning challenges Over and above the organisational challenge, linked to sub-contracting of the operations, decommissioning of the Ulysse reactor represented 1200 days of work. Given the low power of the reactor, the safety and radiation protection issues were minimal. No significant event was reported during the decommissioning operations. n  226 tons of radioactive waste were removed to the VLL waste management route. n  512 tons of conventional waste were taken away. n  ASN is currently reviewing the BNI* delicensing application*. Decommissioning challenges • 21

Some BNI* decommissioning work uses standard techniques, albeit adapted to a nuclear environment. However, certain operations require innovative technologies and tools (robotics, virtual reality, remote-operation, new decontamination processes, etc.), which are specially developed to replace humans in irradiating or inaccessible environments, or to address complex needs on a case by case basis. Round-up of some of the practices used. Using specific tools or technologies CUTTING TOOL DESIGNED FOR DECOMMISSIONING In the auxiliaries cavern, an operator remotely controls the decommissioning operations on contaminated vessels. View on the control screen of a vessel being cut. Here in the Chooz A NPP. ©Philippe Dureuil/Médiathèque IRSN OPERATORS WORKING IN A CONTAMINATED ZONE WEARING A VENTILATED HAZMAT SUIT The ventilated hazmat suit, connected to a breathable air generating unit, is at a slight overpressure by comparison with the contaminated outside environment; it enables the operator to breathe and protects them from any contamination. ©C.Jandaureck/Cadam/ CEA – CEA Valduc * See glossary page 30 DECOMMISSIONING OF THE CHOOZ A REACTOR PRESSURE VESSEL Demolition worksite. Raising and removal of the reactor pressure vessel closure head. ©EDF 22 • Les cahiers de l’ASN • June 2022 BNIs BEING DECOMMISSIONED

“SERVAL” RADIOACTIVE MATERIALS CUTTING ROBOT This robot enables a remote operator to carry out decommissioning operations using a remote-operated robotic arm mounted on a mobile platform. It has two cameras. ©CEA “RODEC” CUTTING ROBOT WITH ITS RACK AND ACCESSORIES Three cutting processes are used: plasma, wiredrawing, laser. Here in the Creys-Malville NPP. ©EDF – Creys-Malville WORK WEARING A PROTECTION SUIT Here in the nuclear waste zone on the site of the Brennilis NPP. ©EDF Decommissioning challenges • 23

And elsewhere? With regard to the decommissioning of nuclear installations following their final shutdown, the international consensus, as expressed in the IAEA safety standards, recognizes two strategies: • deferred dismantling: the parts of the installation containing radioactive substances are kept in or brought to a safe state for several decades before the decommissioning operations begin; • immediate dismantling: decommissioning is initiated as soon as the facility is shut down, without a waiting period, although the dismantling operations can take a long time. United Kingdom The United Kingdom has about thirty definitively shut down power reactors, the vast majority of which are gas-cooled, but there are also a few reactors using other technologies (advanced gas-cooled reactors, heavy water reactors, fast neutron reactors), as well as half-a-dozen definitively shut down research reactors. Although immediate dismantling is legally possible, the strategy currently most widely used in the United Kingdom for power reactors is deferred dismantling. The main reasons put forward are the high level of activation of certain materials (such as graphite), which require decay times of several decades before handling, and the lack of disposal routes for radioactive waste in general. Canada In Canada, the NPP delicensing* plans cover a 50-year period. The licensee wishing to obtain an operating license for an NPP is required to present a delicensing* plan which specifies how they intend to manage the decommissioning and decontamination of their installation. As soon as the delicensing* permit is obtained, implementation of the plan can begin. The activities in this phase include the decontamination and dismantling of the installation. At present, 6 pressurised heavy water nuclear reactors (PHWRs) are undergoing decommissioning. Decommissioning strategies can vary from one country to another. However, most of them refer to the standards set out by the International Atomic Energy Agency (IAEA). United States In the United States, the licensees of nuclear installations (civil or military) can choose from among three decommissioning strategies: immediate dismantling, deferred dismantling, or isolation of the installation by encapsulation (entombment) until radiological levels compatible with delicensing* are attained. To date, about ten nuclear installations have been decommissioned and twenty are undergoing decommissioning. Twelve reactors, including 6 PWRs and 4 boiling water reactors (BWR) are undergoing deferred dismantling and 10 others immediate dismantling, including 4 PWRs and 5 BWRs. * See glossary page 30 24 • Les cahiers de l’ASN • June 2022 BNIs BEING DECOMMISSIONED

Germany After the Fukushima Daiichi accident, Germany decided to abandon nuclear power before the end of 2022. A total of 29 reactors are currently being decommissioned. The site of the 100 MWe heavy water reactor in Niederaichbach has been completely cleaned out and decommissioning of 3 other reactors has been completed. Recently, the 1400 MWe PWR type Phillipsburg 2 reactor was shut down and is being decommissioned, along with the 1344 MWe BWR type Gundremmingen NPP reactor C, the and the reactors of the Grohnde and Brokdorf NPPs. Belgium The decommissioning of the RB3 pressurised water reactor, which started in June 1987, is the first of its kind in Belgium and indeed in Western Europe. The European Commission selected BR3 as the pilot project to demonstrate the technical and economic feasibility of reactor decommissioning in real conditions. According to the decommissioning plan, the reactor will be fully decommissioned by the end of 2023. Spain In Spain, 3 reactors have been definitively shut down, but the dismantling strategies differ according to the reactor technology. The Vandellós 1 gas-cooled reactor is undergoing deferred dismantling, owing to the lack of a management route for graphite waste. Deferred dismantling is also the option chosen for the Santa María de Garoña reactor, shut down in 2013. In 2011, decommissioning of the José Cabrera NPP in Zorita began, after its shutdown in 2006. As at 31 December 2020, it is estimated that more than 90% of the envisaged decommissioning operations have been carried out. Russia In Russia, several power reactors are undergoing or awaiting decommissioning. These are mainly PWRs and reactors with a graphite moderator. Although the decommissioning preparatory operations have been performed, the dismantling strategy for these reactors has not yet been completely determined. Japan In Japan, 24 reactors are currently undergoing or awaiting decommissioning, including the 6 reactors on the Fukushima Daiichi site and 3 reactors already definitively shut down prior to the accident. In most cases, the final shutdown decision was driven by profitability concerns, given the scale of the work required to ensure compliance with the new safety standards. The strategy generally adopted comprises an initial period of about a decade in which the reactor is kept in safe conditions, before decommissioning operations begin. Decommissioning challenges • 25