For reasons of prudence, the estimate also includes an assessment of risks and uncertainties as follows:
The above method for assessing risks and uncertainties leads to an overall margin of some 15.7% for the whole fleet (19.5% for the first 900MW unit).
Since its in-depth revision in 2016 this cost estimate has been reviewed annually. The reviews have led to non-significant annual adjustments.
In 2021, to take account of the impacts of the longer depreciation period for 1,300MW-series plants, the sequence of operations for dispatching waste from decommissioning was adapted to reflect the increase in decommissioning waste to be sent for interim storage in certain years.
Also, the reference cost for decommissioning of the first 900MW units was updated following preliminary studies conducted in preparation for the decommissioning of Fessenheim, and experience gained at the beginning of the pre-dismantling phase. This update also incorporates optimisation of the industrial scenario for management of decommissioning waste before storage, involving prior processing to reduce the volumes stored. Extrapolation of these elements to the whole PWR fleet has a limited impact on the provisions for decommissioning nuclear plants in operation: they are increased by €149 million via adjustment to balance sheet assets.
EDF confirms its analyses through an international intercomparison, taking care to identify and characterise a number of factors that could distort direct comparisons, for example differences in the scope concerned by the cost estimate, or national and regulatory contexts.
Based on the estimates of the different types of cost, the benchmark cost to completion (in 2021 euros) for decommissioning of the first two 900MW units (Fessenheim) amounts to approximately €0.8 billion, giving an average of
€0.4 billion per initial 900MW unit, compared to an average cost of €0.36 billion for the entire PWR fleet, including the series and mutualisation effects described above.
Decommissioning of shut-down reactors involves pilot operations corresponding to four different technologies, each with clear specificities: a PWR reactor at Chooz A located in a cave, UNGG (natural uranium graphite gas-cooled) reactors at Bugey, Saint-Laurent and Chinon, a heavy water reactor at Brennilis, a sodium-cooled fast neutron reactor at Creys-Malville, and the first-of-a-kind second-generation PWR reactor at Fessenheim.
The decommissioning costs are based on contractor quotes, which take account of accumulated industrial experience, unforeseeable and regulatory developments, and the latest available figures. They have been revised annually since 2015. In 2015 the industrial decommissioning strategy for UNGG plants was totally revised. The previously selected strategy was based on a scenario involving “underwater” dismantling of caissons (UNGG reactor buildings) for four of the reactors, with direct graphite storage in a centre currently under examination by ANDRA (see note 28.2 “Long-lived low-level waste”). Several new technical developments showed that the alternative “in-air” dismantling solution for the caissons would improve industrial control of operations and was apparently more favourable in terms of safety, radioprotection and environmental impact. The Company therefore selected a new “in-air” dismantling scenario as the benchmark strategy for all six caissons. This scenario includes a consolidation phase, building on experience acquired from dismantling the first caisson before beginning work on the other five. The decommissioning phase will ultimately be longer than previously planned, leading to a higher estimated cost due to the induced operating charges.
Updating the industrial decommissioning scenario for permanently shut-down power plants, particularly UNGG plants, led to a €590 million increase in the provision at 31 December 2015.
The review of decommissioning provisions for permanently shut-down plants in 2016 led to non-significant adjustments, apart from one increase of €125 million for a specific installation (the Irradiated Materials Workshop at Chinon). In 2017 and 2018, this annual review gave rise to non-significant adjustments.
The amended industrial scenario for dismantling of the UNGG reactors in 2015 was presented to the ASN’s commissioners on 29 March 2016. In 2018 the ASN issued its main questions and conclusions about the UNGG strategy file. A consensus was reached regarding “in-air” dismantling for all reactors, the usefulness of an industrial demonstrator, and the timetable for dismantling the first-of-a-kind reactor (Chinon A2), but discussions continued regarding the dismantling timetable for the other 5 reactors. EDF’s proposed schedule allowed for significant experience-based adjustments (after dismantling the first reactor) before beginning almost simultaneous dismantling of the other 5 reactors. On 12 February 2019, EDF presented all the information justifying the Group’s chosen timetable to the ASN’s commissioners. The ASN then issued draft decisions that were submitted to public consultation between July and November 2019, setting the deadline for filing regulatory applications for authorisation of dismantling work, and the dismantling schedule to be included in the applications. In those draft decisions, the ASN acknowledged that the required operations are complex, and that EDF’s proposed risk control strategy (industrial demonstrator, significant experience with a first reactor) is justified. However, it asked for work on the five reactors after the first-of-a-kind reactor to be brought forward slightly and begin no later than 2055.
In view of the ASN’s draft decisions, the nuclear provisions were increased in 2019 by a total €108 million: €77 million for decommissioning provisions for permanently shut-down nuclear power plants and €31 million for provisions for long-term radioactive waste management (long-lived low-level waste, very low- level and low and medium-level waste).
The ASN’s decisions concerning dismantling of UNGG reactors were published on 17 March 2020 and did not contradict the principles of the draft decisions of 2019. Consequently, the nuclear provisions for decommissioning of UNGG plants were not subjected to any particular re-estimation in 2020, and they reflect the best estimate of the industrial and technical scenario.
In 2020, the annual review of the cost estimates for decommissioning of permanently shut-down plants led to a €45 million increase in provisions due to critical path delays following suspension of work during France’s first lockdown phase, and a major unforeseen event associated with suspension of segmentation work on vessel internals at Chooz A. The costs for decontamination of civil engineering work were also updated, leading to a €43 million increase in provisions for the entire scope of permanently shut-down plants.
In 2021, the annual review of the cost estimates for decommissioning of permanently shut-down plants led to a €77 million increase in provisions following revision of the industrial decommissioning strategy for Chooz A. That strategy has shifted to a full continuous decommissioning scenario, dropping the period of cave runoff water surveillance between the end of installation dismantling and the start of final dismantling and decontamination work, as the quality of the water means this is no longer necessary. Also, the cost estimate for decommissioning of the APEC Fuel Storage Workshop at Creys-Malville – a facility operated by EDF with the principal activity of storing fuel from the Superphénix reactor – was updated based on Summary Preliminary Plan studies conducted in 2020-2021, leading to a €61 million increase in provisions.
Finally, in accordance with its powers under Article 594-4 of the Environment Code, in June 2020 the DGEC commissioned an external audit of the valuation of dismantling operations for EDF’s permanently shut-down nuclear facilities (a UNGG facility and management of long-lived low-level waste, Superphenix and Brennilis), conducted by a consortium of specialist firms. This audit took place from December 2020 to July 2021, and the audit report was posted on the Ministry for the Ecological Transition website in November 2021. Its conclusions (confirming the ASN’s observations during its inspection of complex project management, the conclusions of which were released in the first quarter of 2021) highlights “an organization with a structural focus on execution of dismantling projects”, an “annual estimation and revision process that is robust, and provides good traceability for the assumptions used and the original data”, and “a long-term industrial approach to overcome the small number of technological challenges that remain”. Finally, the report states that apart from a non-significant correction (taken into account in the 2021 provisions), “the provisions are coherent with the basic scenarios or the projects and cover the full scope of expenses for the scope audited”, and of “adequate sizing” through testing the sizing of EDF’s expenses and provisions.
