Universal Registration Document 2021

The industrial and natural risks (RIN) network within EDF ensures that the new requirements are monitored, appropriated and integrated on the sites

Furthermore, the Group is committed to biodiversity through its corporate social responsibility concerns relating to the preservation of the planet’s resources (see section 3.2)

2.2.5 Specific risks related to nuclear activities

5A – Failure to comply with the objectives in terms of operation and/or in terms of extending the operating life of nuclear power plants (France and United Kingdom)

Summary : The Group may not meet its nuclear power plants’ operating objectives in terms of safety and availability, notably in the case where controls or defect detection would lead to modifications on the nuclear French fleet. It may also not continue operating its reactors beyond the current planned expiry date, or even be authorised to operate them until that date in both France and the United Kingdom. In addition, the Group may not be able to control costs and deadlines for upgrading its operating fleet (Grand Carénage in France), which represents a major risk for the Group.

Criticality : ●●● Strong

a) Context

The fleet of nuclear reactors that the Group currently operates in France is highly standardised (see section 1.4.1.1.2.1 “EDF’s nuclear fleet in France”). This enables the Group, in particular, to achieve economies of scale, to apply improvements made to its newest reactors to all reactors and, in the event of a reactor malfunction, to anticipate the measures to be taken with the other reactors. The Group has been aiming for several years to continue operating its nuclear power plants in France longer than 40 years

On 15 December 2021, EDF has announced the phenomena known as “stress corrosion” near welds in the safety injection system (RIS) pipes as part of the ten-year inspection of reactor No. 1 at the Civaux plant. Similar defects have been detected in other plants. These phenomena lead to unplanned shutdowns and inspections and have a significant impact on nuclear generation, the medium-term consequences of which are difficult to assess.

During the periodic reviews carried out during the ten-yearly inspections (VD) and following the Fukushima accident in Japan, the Group drew up a major work programme, called Grand Carénage, the principle of which was approved by the Board of Directors (see section 1.4.1.1.2 “Nuclear power generation in France”).

Following the French State’s decision to shut down the Fessenheim nuclear power plant early, the two reactors were definitively shut down in 2020.

In the United Kingdom, the currently planned operating period 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 8 years on average and the objective is to increase the operating life of the PWR power plant by 20 years after the currently planned 40 years (see section 1.4.5.1.2.2 “Nuclear generation”). The two reactors at Dungeness were permanently shut down on 7 June 2021 and those at Hunterston B on 26 November 2021 and 7 January 2022 respectively.

b) Main risks

Nuclear fleet in France

• This standardisation of the fleet has a potential parallel risk of the dysfunction being common to several reactors or to a generation or series of reactors (see section 1.4.1.1.2.1 “EDF's nuclear fleet in France and its operation”)
• 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 the above-mentioned phenomena known as “stress corrosion” led to the shutdown of the other N4 range reactors. The preventive inspections carried out revealed similar evidence in other reactors. The completion of inspections, some of which were destructive, the examination of technical solutions and their deployment led EDF to draw up in February 2022, in consultation with the ASN, a prioritised list of reactors on which inspections will be resumed with optimised resources and taking into account feedback.

The list of pipes potentially affected by these phenomena has not yet been finalised. Thus, the programme of inspections and repairs on the pipes potentially affected by the stress corrosion phenomenon constitutes a major risk in terms of nuclear generation. It has led the Group to revise its nuclear generation estimate for 2022 and 2023 ⁽¹⁾. To date, the Group is not in a position to analyse the impacts beyond 2023.

Checks could be further extended within the nuclear fleet in close consultation with the ASN. They could result in new investigations and potentially long and costly repairs.

• During the periodic 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 ⁽²⁾ , make it possible to confirm the safety margins available for the operating periods under examination but may also lead to 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 to the already very ambitious initial programme, increasing the risk on the ability of industrialists to make the necessary investments within the stipulated deadlines
• In accordance with the French Environmental Code, the provisions proposed by EDF during reviews after the 35th year of operation will be submitted reactor by reactor to the ASN for authorisation, after a public enquiry. For Tricastin 1, whose VD4 (head of series) ended with recoupling on 23 December 2019, the periodic review conclusion report (RCR) was transmitted in February 2020, and will be the subject of a public enquiry from 13 January to 14 February 2022, after publication of the ASN’s generic opinion on the VD4. The ASN’s opinion on the Tricastin 1 RCR is expected to be issued at the end of 2022. At the end of 2021, the VD4s of the Tricastin 1, Bugey 2, Bugey 4 and Tricastin 2 reactors were completed and the VD4s of Dampierre 1, Bugey 5 and Gravelines 1 were underway. Each ASN opinion may include site-specific requirements in addition to the requirements of the generic opinion, impacting industrial load and costs.

(1) See EDF press releases of 7 February 2022 and 11 February 2022.

(2) Four reactors in the United States have been licensed to operate for up to 80 years. For six others, the licence application is currently being processed: The Nuclear Regulatory Commission (NRC) staff has defined subsequent license renewal (SLR) to be the period of extended operation from 60 years to 80 years (www.nrc.gov/reactors/operating/licensing/renewal/subsequent-license-renewal.html).