French nuclear fleet situation – FAQ

The french nuclear power plants are facing the winter 2022-2023 in a most unusual situation. You will find below the answer to frequently asked questions regarding their status.

For the most up-to-date situation, please check the news on the home page.


A quick overview of the current situation

Recently, weather conditions have not been ideal for solar and wind production. We are going through what can be referred to as Dunkelflaute (also known as anticyclonic gloom), with temperatures 3°C lower than average, low wind (the maximum output for French windfarms since December 4th was 3 GW out of 19,5 GW capacity), and overall cloudy conditions.

However, the long-awaited comeback of reactors on the grid has finally arrived. Nuclear production improved by almost 10 GW in one month and 4 GW in a week but, at 67% of the capacity and 40 out of 56 reactors delivering, still stays way below standard. The following week is expected to be tense as France is still dependent on large imports and generation margins remain very low. Yet, RTE [Eletricity Transmission Network] did not issue any alert so far. Besides, on December 12th France was still able to deliver up to 3 GW to the UK [10h-21h30].

General rule: As EdF rarely delivers on time, one should not rely too much on their forecast and prefer RTE’s instead. Still, for the first time in months, RTE’s mid-November central hypothesis proved a little pessimistic as EdF has already achieved the delivery of 1 more GW of power than expected for the end of the year 2022.

Synthèse hebdomadaire de la consommation électrique française | RTE (

For a more detailed overview of the situation, here is the table of the status of each nuclear reactor :

The french nuclear fleet has a generally lower load factor than other countries

Almost no maintenance is done during operations, except for large maintenance & modification program “Grand Carénage Program”, where more than 70% of works on site are implemented during operations.

Fuel reload: every 12 months for most of the 900 MWe units; every 16 to 18 months for other reactors as in most other countries.

Part of the fleet is capable of load following (partial flexibility of the electricity production), which is done not only with regards to the marginal cost of nuclear electricity, but also for usage value (saving fuel by pausing or lowering production so it can generate when market prices are higher).

Stricter labour laws than, for instance, in the USA, means longer maintenance periods in France: 6 to 18 months for 10-yearly outages (VD); 60 to 80 days for regular outages (VP); 30 to 40 days for refueling outages (ASR).

As a consequence of all this, the French nuclear fleet has generally a lower load rate than other countries.As a consequence of all this, the French nuclear fleet has a generally lower load factor than those of other countries.

This is an identified issue, and EDF has started a large program, called START 2025, to drastically improve outage management performance on all sites. This should lead to progressive improvement in the coming years.

Size effect

EDF France is the largest single country nuclear fleet operator in the world. This leads to less optimal fleet operation: each maintenance delay on one reactor causes cascading delays on the others.


Current situation of the french nuclear fleet

From 2022 to 2025: very intense maintenance and renewal program performed on the French nuclear fleet. For this period, a very low or even negative electricity production margin was already anticipated in early 2020 in France in winter coldest weather.

Back in June 2020, RTE had indicated that, in case EdF confirms reactor outages for maintenance schedule, it forecasted, a “situation of special vigilance” with “lowest nuclear fleet availability from this summer until at least next winter”.


Closure of 14 reactors before 2035 still in the French law

Though president Emmanuel Macron announced, during the Belfort speech early 2022, that no other reactors (than Fessenheim, already closed in 2020), will be closed, the closure of 12 more reactors is still included in the 2019 PPE law. Accordingly, the nuclear sector built a roadmap around this PPE law objectives including operational, organizational changes and cost optimization to stick to the closure target. The sector, set to decrease in the following years, didn’t attract many candidates, and some of the most skilled employees left.

10 year safety review (VD)

All reactors are inspected once a decade in a so-called ten-yearly exhaustive special inspection & testing. Authorization to restart is given by ASN (the French Nuclear Safety Authority) only after completion of upgrades to comply with the latest safety regulations and successful tests.

“Grand Carénage” 2014-2028 program

“Grand Ca“Grand Carénage”: in the context of the 4th 10-yearly safety review, a large upgrade program allowing the 900 MWe reactors to meet new regulations has to be performed to get ASN’s approval to run for ten more years, past the originally expected operating period of 40 years. The corresponding amount of work, spread over several years, leads to outages lasting from 6 to 18 months, obviously hindering overall fleet availability.

In addition to those intense but scheduled maintenance programs, additional shortage has resulted from unexpected damage discovered first on a reactor at the Civaux site at the end of 2021 (see below under Stress Corrosion Cracking).

Covid 19 consequences

Maintenance & refueling have been rescheduled after COVID 19 due to the lockdowns and the application of strict, time-consuming safety rules, thus still affecting production in the current year: operations that should have been done in 2020 have been delayed to the next years.

Stress Corrosion Cracking

Strain corrosion: 12 reactors have been shut down so far, either for inspection, or for repair. In both cases, the corresponding piping had to be cut, then welded back, no matter what the inspection revealed. 

Stress corrosion cracking (SCC) discovered at the end of 2021 on the youngest four reactors (N4 series) on the safety injection system (RIS or SIS) line and/or residual heat removal system (RRA or RHR) line led to the shutdown of 12 reactors. At first, 6 of the piping sections were cut out for further inspection, showing SCC generic issues only on one of them ; SCC was detected on a single defective weld in 2 of them. Removing piping unaffected by SCC is henceforth unnecessary, EDF having put in place non-destructive ultrasonic tests, validated by safety authority ASN. Pipe sections have now been replaced on all those 6 reactors, allowing restart of 5 of them; the last one is to be restarted in early January. RRA & RIS (RHR and SIS) pipe sections on the next 5 reactors where SCC was diagnosed are currently being replaced, and 2 more reactors have been shut down awaiting the repairs.

Most affected reactors by SCC are the most recent N4 (all 4 are affected) and P’4 (4 out of 5 The reactors most affected by SCC are the most recent N4 (all 4 are affected) and the P’4 series (4 out of 5 are affected, generally with minor cracks). All remaining P’4 reactors are to be diagnosed before the end of 2023 – there are 7 more to be analysed. All remaining P4 & 900 MW (P0 to P2 series) are to be diagnosed by the end of 2024.

Four-week strike in September-October

20 of the French reactors were affected for a four-week-long strike in September-October 2022, causing several weeks’ delay in maintenance operations for several units. Unions were seeking a salary increase for workers.

“No trade-off with safety”

Even under such exceptional conditions, EDF categorically states that “there is no trade-off between reactor safety and security of electricity supply.” ASN, the regulatory body, support this position. See the complete message on the SFEN website:

Those are the main explanations of the outage of, currently, 16 out of 56 reactors. But there is another thing: EDF almost never delivers on scheduled time.


Why does EDF almost never deliver on time?

Dates indicated by EDF in the REMIT notices are a best case scenario. EDF indicates “Outage suspension may be extended”.

Delayed restart of reactors is due to many factors, including:

  • General unreliability of initial schedule (initial schedule based on targets, not on previous achievements).
  • September 2022 to November 2022 – nuclear reactor employee strike delaying maintenance operations (see above), leading to the rescheduling of several restarts on part of the fleet.
  • Rescheduling due to different analysis of the situation between EDF and ASN. Ex: ASN rejected EDF maintenance plan and added new requirements (Cattenom 1; nov 4th, 2022).

Cattenom : deux soudures doivent être réparées avant son redémarrage – 04/11/2022 – ASN


Will EDF restart all of its reactors?

Yes, if French policymakers do not order the closure of other reactors, which is very unlikely in the near future. Five of the reactors with reconstructed RIS & RRA (SIS and RHR) circuits are already back on the grid.

(NB: Fessenheim, which has been closed for political reasons in 2 020, will not reopen.)


Will the French electrical system hold this winter?

According to RTE mid-November analysis, shortages will be less likely in December than expected in the worst case scenario (except if a freezing cold wave comes to France), tough According to RTE’s (French transmission grid operator) mid-November analysis, shortages will be less likely in December than expected in the worst-case scenario (except if a freezing cold wave comes to France), even though only 40 GW of nuclear capacity would be on the grid at the end of December/beginning of January (up from approx. 35/36 GW at the beginning of December). RTE sees 45 GW as a best case in January. They are not so optimistic about having the N4 (most recent & highest-capacity) reactors on the grid at the beginning of 2023. RTE’s central forecast proved to be a little pessimistic, since nuclear reactors are already delivering 41 GW (1 GW above RTE’s forecast for the end of December).

But water reservoirs are OK, and natural gas reserves are full, so the back-ups will be there, and demand from electro-intensive industries has shrunk from 11 to 13%. Given the situation, 2 to 3 hours rotating power cuts are still possible in January/February. The risk of a general blackout is still very low.

Thus, for RTE, in France, “electricity prices on futures markets for the beginning of 2023 still include a disproportionate risk premium compared to the forecast supply/demand”, as was the case last summer for the 4th semester 2022, but “these types of prices having not yet been confirmed on the spot market”.

This can be confirmed by viewing the french base electricity price in December – data from eex website (futures for French electricity; price in €/MWh). Although start-of-month climate conditions are way below average with regards to wind and temperature, the electricity price has almost halved since the beginning or November:

And on the futures market, January has also halved, though still at a very high level (635€/MWh for base electricity):


Will France be able to provide electricity to its neighbors in the heart of the winter, from December to February?

The French electricity system is thermosensitive, therefore it relies on its neighbors (mostly Germany and Belgium, but also Spain, UK and Switzerland) when temperature are at their lowest, especially when nuclear production is low and the wind is not blowing. Still, France has remained a net electricity exporter over the entire winter period (early December to end February) at least since 2015, except during winter 2021-2022.

During winter 2022-2023, France will most certainly again be a net electricity importer. Will France be able to get enough electricity for its own needs, and still export some to Italy, Switzerland & UK? That will mostly depend on temperature conditions (1°C less means an additional 2.4 GW of demand), wind conditions (the risky moment = Dunkelflaute – no wind, no sun) and nuclear fleet availability through January (40 GW? 45 GW?).

Hydro stocks are adequate; natural gas storage is almost full (see above). Therefore, in the best-case scenario (nuclear availability of 45 GW+ in January), a decrease in industry demand (3 to 4 GW decrease compared to 2021), plus a decrease in residential demand, will more or less make up for the lower availability of nuclear reactors compared to winter 2021-2022 (approx. 49 GW max).

Electricity flows (import/export) in December / January 2015-2022:

Bar Charts Electricity Generation | Energy-Charts

Bar Charts Electricity Generation | Energy-Charts



French Nuclear Fleet

Fleet of 56 of operational reactors, totalizing approximately 61 GWe:

  • 32 reactors generating 900 MW of electricity (4 CP0, 18 CP1, 10 CP2)
  • 8 reactors generating 1 300 MW of electricity (P4 REP 1300)
  • 12 reactors generating 1 300 MW of electricity (P’4 REP 1300)
  • 4 reactors generating 1 450 MW of electricity (N4 REP 1450)

Where to find data on the french nuclear reactors/electrical system?

Real Time general Data

Total electricity production, export & import (real time & history):

Real time information data & market: View data published by RTE – RTE Services Portal (

Total CO2 emission by countries: Electricity Maps | Émissions CO₂ de la consommation électrique en temps réel

Real time data for French Nuclear reactors

French nuclear Reactors availability from all 56 units with map & info about maintenance & load monitoring (flexibility):

Production & relevant information from all 56 french nuclear reactors

French nuclear availability timeline – Dashboards – Dashboards – Grafana (

Documents from french institutions

RTE / French transmission system operator synthesis. Updated every month: Analyse-passage-hiver-2022-2023-actualisation-novembre.pdf (

And RTE shorter synthesis, updated every week: