EDF’s industrial goal for the preparation for the future of the nuclear fleet rests primarily on the following strategic areas:
On 15 September 2011 and in light of the accident at the Fukushima nuclear plant in Japan, EDF submitted 19 Additional Safety Assessment reports to the ASN, at its request, one for each of its nuclear sites, encompassing all its existing reactors and all those under construction.
These assessments consisted of re-examining the defences of existing power plants and those under construction, in light of the events in Japan, taking into account issues set out in the specifications drafted by the safety authorities.
Thus, the safety margins were reassessed against the risks of earthquakes and flooding, when dealing with situations of simultaneous loss of the cooling source and power supplies and the consequences of severe accidents.
These assessments also led to inquire whether certain changes to the scenarios planned beyond situations used for the sizing of the protection systems, would lead to a worsening of the consequences in terms of safety (“cliff effects”). They finally led to deterministically consider the extreme situations that substantially exceed those used in the design of nuclear installations and subsequent safety reviews.
The safety of EDF’s nuclear fleet is based on the principle of continuous improvement: existing and new facilities continuously benefit from feedback from all power plants, and lessons are learnt from incidents and accidents that may occur in the world.
Finally, the ASAs also re-examined the rules applied in outsourcing.
These analyses confirmed first and foremost the adequate level of security through out the EDF nuclear power fleet, particularly because of the periodic reviews carried out in France since the end of the 1980s. EDF also proposed additional measures to the ASN that exceed those considered for sizing safety systems, to contribute to further improving the current safety level of power plants.
In its opinion to the government published on 3 January 2012, the ASN states, on the basis of the analyses of its technical support, that “after the additional safety assessments on priority nuclear facilities, the ASN considers that the facilities examined show an adequate level of safety, and that it will not thus request the immediate shutdown of any of them”. At the same time, the ASN considers that“continuing to operate these facilities requires increasing their robustness, as soon as possible, to an extent beyond existing safety margins, to handle extreme situations”.
The ASN also recommended the “hard core” concept and the FARN system (see section 1.4.1.1.2.2 “Environment, nuclear safety, radiation protection”). The “hardcore” will be made up of the plant’s structures, systems and components that can withstand situations studied in connection with ASAs. On 26 June 2012, the ASN made 19 decisions requiring EDF to follow over 600 technical requirements, which set regulatory requirements according to the post-Fukushima action plan. These technical rules require that all nuclear sites must have an organisation and local crisis centres resistant to the occurrence of a large-scale event affecting several facilities.
For EDF power plants, the prescribed “hard core” must in particular have“bunkerised” electrical resources in each unit. In the meantime, a temporary back-up diesel generator was installed at each of the 58 units in 2013. The complete definition of the “hard core” was covered in technical rules issued by the ASN inJanuary 2014.
The provisions of the French Environment Code do not set a limit on operating life but require a review of facilities every ten years in light of applicable rules and updates of assessments of the risks facilities pose to protected interests, taking into account the state of the facilities, the experience gained during their operation, new developments in nuclear science, and rules applying to similar facilities
(safety standards).
EDF’s industrial strategy is to operate the fleet beyond 40 years in the best conditions of safety and performance, considering the significant investment linked to the third ten-year inspections and the post-Fukushima improvements on the one hand, and the energy needs of France on the other. This target is consistent with trends observed around the world for reactors using similar technologies. To this end, EDF has implemented industrial and R&D action plans. Actions have been launched to renew the major components that can be renewed and solutions are being studied to demonstrate the capacity of non-replaceable equipment such as the confinement containment building and reactor vessels, to ensure their operation up to 60 years.
An extension to the life of the current nuclear fleet would enable, whilst respecting the absolute priority of nuclear safety and as part of the multi-year energy programme, better use of the industrial base it represents and the spreading of the commissioning of new plants over time.
In the first half of 2016, all the technical, economic and governance conditions necessary to match the amortisation period of the 900MW power plants in the French nuclear fleet with the Group’s industrial strategy were met. On 28 July 2016, the Board of Directors of EDF approved the extension of the accounting amortisation periods of PWR 900MW series power plants in France (excluding Fessenheim) from
40 to 50 years from 1 January 2016 onwards, without prejudice to the ASN’s position on the measures suggested by EDF for each of the nuclear units in question.
It is based on the technical capacity of the PWR 900MW fleet facilities to operate for at least 50 years, supported by international benchmarks, as well as by the investments made progressively under the Grand Carénage programme (see section 1.4.1.1.2.1 “Investment programme for the existing nuclear fleet in France”). These investments will enable the PWR 900MW series to reach a level of safety as close as possible to that of the EPR, and one of the highest internationally, after its fourth ten-year inspection (VD4).
On 23 February 2021, the ASN ruled on the terms for continuing to operate 900MW reactors beyond their fourth scheduled inspection. The ASN "deems that the measures put forward by EDF, coupled with its own recommendations, open up the way for the continued operation of 900MW reactors for ten years after their fourth regular re-examination".
Tricastin 1 was the first 900MW reactor unit to successfully undergo its fourth
ten-year inspection (VD4). It was decoupled on 1 June 2019, and diverged at the end of its ten-year inspection on 19 December 2019.
The extension of the operating life of the 900MW units will be implemented according to the multi-year energy programmes for 2019-2023 and 2024-2028.
The amortisation period of the other series of France’s nuclear fleet (1,300MW and 1,450MW), which are more recent, currently remains at 40 years, because the conditions for an extension have not been met. The subsequent extension of the most recently installed reactors in the French nuclear fleet is at the heart of the Group’s industrial strategy.
