In the United Kingdom, the operating period currently planned for the reactors in EDF Energy’s existing nuclear fleet ranges from 41 to 47 calendar years for advanced gas reactors (AGRs) and is 40 years for the Sizewell B pressurised water reactor (PWR). Since EDF Energy acquired them, the operating lifespan of the AGR power plants has been extended by 6 years on average and the objective is to increase the operating life of the PWR power plant by 20 years in addition to the 40 years currently planned (see section 1.4.5.1.2.2 “Nuclear generation”). The two reactors at Dungeness B were permanently shut down in June 2021, those at Hunterston B in November 2021 and those at Hinckley Point B in July and August 2022.
b) Main risks
Nuclear fleet in France
- This standardisation of the fleet has a potential parallel risk of the dysfunction being ordinary to several reactors or to a generation or series of reactors (see section 1.4.1.1.2 “Nuclear power generation in France”).
- The Group may be required to make significant or costly repairs or modifications to all or some of its plants. Events may occur that could have an impact on the operation of the fleet or on its output, which could lead to a temporary shutdown or closure of all or part of the fleet.
In particular, the detection of indications (termed “stress corrosion”) discussed above brought about the shutting-down of the reactors of the N4 series. The preventive inspections carried out revealed similar defects in other reactors.
Checks could be further extended within the nuclear fleet, in close consultation with the ASN. They could result in further investigations and entail potentially lengthy and costly repairs.
- During the periodic ten-year reviews, the ASN decides on the measures taken by the operator and may give additional instructions for each reactor. Solutions are being studied to demonstrate the capacity of non-replaceable equipment such as the containment building and reactor vessels, to ensure their operation up to 60 years. These studies, which are based on data available in France but also internationally (1), make it possible to confirm the safety margins available for the operating periods under examination but may also incur the need to adopt additional protective measures, if necessary, for the existing fleet, which could have consequences on its performance.
- In its decision of 23 February 2021 on the conditions for continued operation of EDF’s 900MWe reactors beyond their fourth periodic review, the ASN found that the measures planned by EDF, supplemented by the responses to the requirements formulated by the ASN, will make it possible to achieve the objectives of the review and that these safety improvements open up the prospect of continued operation of the 900MWe reactors for a period of ten years beyond their fourth periodic review, subject to the implementation of additional measures. These new requirements lead to an increase in investments and an additional industrial load of around 25% compared with the already very ambitious initial programme, increasing the risk affecting the ability of industrialists to make the necessary investments within the stipulated deadlines.
- In accordance with the French Environmental Code, the measures proposed by EDF during reviews after the 35th year of operation will be submitted for each reactor individually to the ASN for authorisation, after a public enquiry. For Tricastin 1, whose VD4 (head of series) culminated in recoupling on 23 December 2019, the periodic review conclusion report (RCR) was transmitted in February 2020, and was the subject of a public enquiry from 13 January to 14 February 2022, after publication of the generic ASN opinion regarding the VD4. The ASN’s opinion on the Tricastin 1 RCR is expected to be issued in 2023. At the end of 2022, the VD4s were completed for the following reactors: the Tricastin 1; Tricastin 2; Tricastin 3; Bugey 2; Bugey 4; Bugey 5; Dampierre 1; Dampierre 2; Gravelines 1; and Gravelines 3 reactors, and the VD4 of Blayais 1 is under way. Each ASN opinion may include site-specific requirements in addition to the requirements of the generic opinion, impacting industrial load and costs.
- In 2016, the Board of Directors approved the extension in the consolidated financial statements of the depreciation period for the 900MW PWR plants, except Fessenheim, from 40 years to 50 years, without prejudice to the decisions of the ASN on the measures proposed by EDF for each reactor individually, after each 10-year inspection. The risk cannot be ruled out that the extension of the operating life of certain 900MW reactors may not be authorised, but an important step forward was taken with the generic opinion issued by the ASN on 23 February 2021.
- The continuing in operation of the other series of France’s nuclear fleet (1,300MW and 1,450MW), which are more recent, remains an industrial objective for the Group. In 2021, the Board of Directors approved the extension in the consolidated financial statements of the depreciation period for the 1,300MW PWR plants from 40 years to 50 years (see note 1.4.1 to the consolidated financial statements for the fiscal year ended 31 December 2022). This accounting estimate does not assume that continued operation will be authorised; such authorisation will be granted unit by unit by the Safety Authority after each ten-yearly inspection, as required by law.
- The potential uncertainties regarding the Grand carénage programme include a possible delay in the processing of the authorisations required to start operations, especially as regards the authorisations expected from the French Nuclear Safety Authority (ASN). Such uncertainties may also concern the manufacture and delivery on site of new equipment or work carried out on-site in a situation where a large number of industrial operations are being carried out at the same time. Furthermore, the Group may not receive the expected operating lifespan extension from the competent authorities. Such extensions could also be obtained under certain conditions, the financial impact of which, in particular in terms of investments, could affect the Group’s strategy with respect to extending the operating life of its reactors or the Group’s ability to pursue its global investment strategy. These events could have a significant negative impact on the Group’s financial position.
Nuclear facilities in the United Kingdom
- Given the nuclear safety rules applicable in the United Kingdom and AGR reactor technology in particular, EDF Energy may not obtain the necessary authorisations from the ONR when the time comes to operate its existing nuclear reactors until the currently planned (AGR) or potential (Sizewell B) end of operation date, or may obtain such authorisations under conditions involving significant expenditure or investment by the Group.
- The ongoing analysis of graphite ageing in the AGR (Advanced Gas Reactor) may lead to prolonged unavailability or early shutdown of the reactors. The cracking of graphite subjected to irradiation must be carefully monitored, with inspections carried out regularly, and controlled by the Office for Nuclear Regulation (ONR), to ensure that there is sufficient knowledge of the core to justify continued operation. Following decisions taken in August 2020 and November 2020, Hunterston B was permanently shut down in January 2022, and Hinckley Point B permanently ceased production in July 2022. Following a life review of the AGRs in December 2021, the projected final shutdown dates for Heysham 2 and Torness have been brought forward from 2030 to March 2028.
- An accelerated fuel withdrawal strategy would be implemented in the event of any risk of an early shutdown of the other AGR plants. If this strategy were to be adopted, a re-examination of the value of the assets may be required.
- Given the ageing of the British fleet and the many technical difficulties encountered, the future level of output of the AGRs currently in service is very uncertain.
Other nuclear facilities
- For nuclear reactors where EDF is not in charge of operation but has financial interests (Belgium, China), the Group is also financially exposed to some risks. The Group may need to contribute up to the amount of its share to costly repairs or modifications to be carried out on these units or to events that may have an impact on their operating lifespan, production or availability. As in France and the United Kingdom, the nuclear safety authorities in these countries may take decisions that require additional work or controls, in particular as regards exploiting feedback from international experience and anticipating potentially precursory events. The Group is also exposed in terms of the value of its assets.
