France’s nuclear “crisis” and UK energy security

France’s electricity generation since June has been running 5-10GW below normal because of nuclear plants being shut down for inspection. France has made up this shortfall by reducing electricity exports – generation from oil, coal, gas, hydro and renewables has stayed about the same. Exports to UK have decreased to the point where overall the UK now exports more power to France than it imports. The exports, however , occur dominantly during periods of low UK demand. The UK still imports up to 2GW of power from France during peak  periods, although it’s unlikely that it would be able to do so should there be a protracted cold spell in Europe this winter.

Data Used

The data used in this post are from Gridwatch, which provides 15-minute grid data for France since October 2014 and five-minute grid data for the UK since May 2009. The UK data are of generally good quality except for some missing intervals. The French generation data contain missing intervals, the same data entered in different intervals, obviously suspect readings and intervals where zero has been entered to signify no data, and corrections have had to be made to clean the data set up. The French total export values are generally reliable but the export/import entries for individual countries (Germany, UK, Belgium, Spain, Italy and Switzerland) contain numerous suspect readings and often do not add up to anything resembling total exports, so they were not used in the analysis. All numbers are daily averages unless otherwise specified.

French Grid Data:

Figure 1 is a stacked bar chart showing France’s average daily generation by source since the beginning of the Gridwatch data in October 2014. Nuclear continues to dominate despite the nuclear plant shutdowns:

Figure 1: France’s total average daily generation by source, October 2014 to October 2016. The month divisions are approximate.

Figure 2 plots generation from all sources relative to demand since October 2014. France had a generation surplus before the nuclear shutdowns began in June of this year, but now generation and demand are at best in balance:

Figure 2: Average daily generation from all sources versus demand, October 2014 to October 2016

Figure 3 compares France’s nuclear generation by month since October 2014. It’s reported that a third of France’s nuclear plants are now offline but 2016 nuclear generation is down by only about 8GW, or about 20%, relative to 2015 generation:

Figure 3: Average daily nuclear generation by month, 2014, 2015 and 2016

Figure 4 plots France’s generation since October 2014 from nuclear plants, non-nuclear sources (oil, gas, coal, hydro, wind, solar) and “exports”, which here are plotted so that diminishing exports show up as an addition to France’s power supply. The decrease in nuclear generation is evident but there has been no significant increase in non-nuclear generation. The “exports” plot shows that France has made up its nuclear shortfall by cutting exports by 5-10GW relative to historic averages. As a result France is no longer a net power exporter – exports and imports are now roughly in balance.

Figure 4: France’s daily average nuclear generation, non-nuclear generation and exports, October 2014 to October 2016

UK Imports/Exports

Average daily power flows recorded by Gridwatch since June 1, 2016 along the IFA interconnector that links the UK with France are summarized in Figure 5. Imports are plotted as positive values because they add to UK supply:

Figure 5: Average daily power flows along the France-UK IFA interconnector since June 1, 2016

Between the beginning of June and mid-August the UK fairly consistently imported ~1.5GW of electricity from France. In mid-August, however, imports from France began to decline, and since early October the UK has been exporting power to France for most of the time. Fortunately for the UK, however, power is exported to France dominantly during UK off-peak hours. During peak hours the UK still imports power from France up to the maximum 2GW capacity of the IFA interconector, as shown in Figure 6:

Figure 6: UK electricity imports from and exports to France, five-minute data, October 7 to 13, 2016


The fact that France has been able to compensate for the lost nuclear generation simply by reducing power exports suggests that the situation has not yet reached “crisis” levels and that it is unlikely to do so unless yet more nuclear plants are taken down for inspection. But if Europe experiences an unusually cold spell this winter while a number of plants are still down the loss of imported power from France could be the straw that breaks the camel’s back in some of France’s neighbors. (Which? I don’t know because I can’t find any up-to-date information on reserve margins in these countries. Maybe someone knows of some.)

But the UK is undoubtedly one. So long as France can continue to export up to 2GW to the UK during peak demand periods the nuclear plant shutdowns should not cause further deterioration in the UK reserve margin this winter. The problem, however, is that a cold spell could cause power flows from France to UK to dry up altogether. There have been occasions in the past where power flows from France to UK were in fact reversed during such cold spells even when no significant number of French nuclear plants were off line. Figure 7 below, which reproduces Figure 7 of my January 2015 post UK interconnectors – a double-edged sword, is an example. The first graph plots IFA interconnector flows over the wintry period in February 2012 when the UK exported power to France for about four weeks with the interconnector working at capacity for much of the time, effectively losing  4GW of peaking capacity in the process. If such conditions were to recur this winter it would probably be lights out for the UK, or France, or both:

Figure 7: UK power exports to France during January/February 2012 cold spell, five-minute Gridwatch data

This entry was posted in Energy and tagged , , . Bookmark the permalink.

50 Responses to France’s nuclear “crisis” and UK energy security

  1. Tom Bates says:

    Why not discuss the reason for the shut downs, why they are affecting all the plants and what are the result of inspections at plants in the past?

    • 2PetitsVerres says:

      According to (fr) it’s due to possible manufacturing errors on steam generators and possible fraud to cover them. It happen a long time ago, but during the construction of Flamanville’s EPR, an anomaly has been detected, triggering further investigation.

      It seems that the company manufacturing it knew about the problem (sorry I’m not going to try to translate the problem, I don’t fully understand it in french, it’s about discrepancy in the material composition) but did (may have) cover it in the documentation. The problem is that this same company did also produced the equivalent part for older power plant, so they have to inspect them, show that there is no security risk and so on. And probably also some investigation about the fraud part.

      • According to reports received from reliable sources the inspections are a) non-diagnostic and b) probably politically motivated.

        • I am assuming that statutory outages in France for boiler equipment are similar to the UK at 3 years? Or is it different for nuclear?

          Surely during such an outage, you would have time to check your steam equipment. i know we do and we have no many. So it does seem a little suspect that the plant would not have the require info to hand and why that would not be enough unless they were deliberately not doing stat outages (In which case it would be shutdown and fines which we are not exactly seeing).

      • Euan Mearns says:

        It was Greenpeace that originally blew the whistle on this one which has to raise some suspicion. On the one hand, if documentation has been falsified creating genuine risk then that is very serious indeed. On the other hand do we or will we ever know if real risks exist? Roger mentions reliable sources. Do we know exactly what tests are being run?

        • Alex says:

          I have heard that the regulator is keen to demonstrate (1) its independence, and (2) its thoroughness. That’s no bad thing, but could be classed as “political”.

          It seems that the fault first identified in the new plant at Flamanville has been existing for decades in France’s older plants, without issue.

          Of course, better safe than sorry, which is why I have a preference for plants operating at atmospheric pressure. It can’t blow – just drip.

          • benjiiiiiii says:

            Dripping molten salts are more problematic than you realise. They don’t freeze. The decay heat makes them evaporate and then condense on other surfaces. A nightmare to decontaminate when the whole containment building is covered in deadly radioactive salt.

  2. Serphin says:

    In 10 days the Swiss are set to vote on whether to drastically accelerate the shutdown of their nuclear capacity.

    A French blackout before then would actually be quite helpful to sway the vote in the right direction!

    • Alex says:

      That would be blamed on nuclear though. A German blackout would be more helpful, though I’m sure they’d blame that in French nuclear as well.

      With the amount of coal and lignite plant, Germany is probably OK till 2021 – 22 when they lose several GW of nuclear.

    • robertok06 says:

      The right direction being building more nuclear plants, of course! 🙂

  3. Denis CLEMENCEAU says:

    Merci pour votre excellent travail. Il me semble que sur les graphiques on observe des pics vers le bas aux changement d’horaire et que toute la période de l’horaire d’été semble au-dessus de la consommation d’énergie au voisinage de l’heure d’hiver. Le changement d’horaire éloigné du temps solaire ne semble pas à première vue une économie d’énergie sur toute la période de l’heure d’été. Au final sur l’année a-t-on une économie d’énergie ou pas ?
    Cordialement (mon anglais est très mauvais)

    • Merci Denis: My French is probably as bad as your English, but I think you are asking how much energy “summer time” saves, if any. I don’t know. I would have to look into it.

    • Euan Mearns says:

      According to Google: Thank you for your excellent work. It seems to me that on the graphs there are downward peaks at schedule changes and that the whole period of the summer schedule seems to be above the energy consumption in the vicinity of winter time . The change in the timetable away from solar time does not seem at first sight to save energy over the whole period of summer time. At the end of the year, is there an energy saving or not?
      Regards (my English is very bad)

    • It doesn't add up... says:

      Je pense que plus important serait la différence entre GMT et CET qui permet à la demande d’heure de pointe de pointe être rencontrée en partie à partir de l’autre fuseau horaire. Peut-être l’Espagne devrait passer au fuseau horaire GMT pour aider à fournir la France.

      I think that more important would be the difference between GMT and CET which allows peak rush hour demand to be met partly from the other time zone. Perhaps Spain should switch to the GMT time zone to help supply France.

      Voici un exemple où vous pouvez voir la commutation de la direction de l’interconnexion entre la France et le Royaume-Uni pour répondre aux exigences de l’heure de pointe différemment par phases.

      Here is an example where you can see switching of the direction of the interconnector between France and the UK to meet the differently phased rush hour demands.

      • Euan Mearns says:

        EU to Introduce Two New Time Zones

        Earlier today Mr Donald Trunk, EU Commissioner for Social Adjustments, launched an initiative that will see two new time zones introduced before the end of 2017. Mr Trunk explained that spreading electricity demand more evenly across the continent will help integrate the new electricity market and reduce peak demand. What better way to achieve integration than to divide the continent into 5 time zones?

        I’m surprised you haven’t heard.

      • Roger Andrews says:

        I was going to observe that peak winter demands in France and the UK are coincident when the one-hour time difference is allowed for, but it seems I’ve been preempted. 😉

  4. dereklouden says:

    Hello Roger, the UK has an additional problem this year in that Centrica’s Rough Storage facility is off-line for maintenance. We have very little gas in storage to tide us over in a cold spell.

    • Joe Public says:

      Hi Derek

      Your source is misinformed.

      1. Ofgem’s Oct 2016 Statutory Security of Supply Report 2016

      50. The peak winter day demand for 2015/16 was 369mcm, which was 96mcm lower than the record winter peak day demand in January 2010. For the coming winter seasonally normal peak demand is forecast to be 310mcm/d. The 1-in-20 peak demand for this coming winter is 472mcm/d with a peak deliverability of 602mcm/d.

      61. GB gas storage is expected to provide a smaller amount of gas over the coming winter compared to previous winters, this figure being somewhat below the capacity of recent years due to a reduction in deliverability at the Rough storage facility. Based on assessments of current storage sites, National Grid estimate deliverability for this winter is approximately 137mcm/d. Given the diverse nature of the GB gas market National Grid expect sufficient flexibility and diversity across all sources to cope with the reduction in storage space for the coming winter.

      62. Centrica Storage Limited has issued a remit notification to say that the Rough storage facility will be available for withdrawal only, as of 1st November 2016 subject to normal operating conditions.

      My Bold

      (1 mcm ~11GWh)

      2. Rough is but one of a number of GB gas storage assets, and it is by far the largest.

      Existing (2016) gas storage facilities = 4.65 BCM ~51.15TWh

      Withdrawal capacity 175.1 MCM/day ~1.926 TWh/DAY Duration up to 67 days (Rough)

      National Grid’s gas storage stock and deliverability today is available from the link below.

      As of today, our stock level is 35,550 GWh, of which Rough holds 13,714 GWh.

      Deliverability today is 1,380 GWh

      [For context, the pride of the electricity storage industry is Dinorwig at 9.1 GWh]

    • Joe Public says:

      1. Before the 2015 pressure issue occurred, Rough offshore gas storage field could store 135.2 BCF (41.1 TWh).

      2. Even in the winter, extract from storage makes up only a small proportion of GB’s total supplies. Most is from linepack.

      3. On the day of peak supply in winter 2015/16, gas storage provided its highest supply of the winter at 98 mcm. (1.078 TWh)

      4. On 4x days in winter 2015/16 demand exceeded 350 mcm. (3.675GWh)

  5. Hugh Sharman says:

    Super job, Roger (as usual!)

    Charts are so much better than words!

    It is very interesting to see that the sheer preponderance of nukes in French generating capacity “forces” them to cycle its nuclear fleet seasonally and explains why, for the last many years, France is nearly always exporting power to all its neighbours, an important additional revenue for the financially tottering EdF.

    It also explains why the existence of so much surplus, low marginal cost, generating capacity historically appears to justify building new inter-connectors to UK, rather than building new dispatchable capacity in UK itself. As French nuclear capacity decommissions and becomes less reliable with age, we are certain to see capacity shortfall all over Europe, during still, cold winter anticyclones.

    In June, 2014, in my paper at there is a useful chart showing how nuclear output varied (widely) between 2011 and 2014. As UK’s nuclear fleet ages further, it will be less and less a resource on which UK planners can depend.

    Thanks again Leo, for the gift that keeps on giving!

    • Thank you Hugh:

      Seasonal cycling of the French nuclear fleet, which involves a lot of summer downtime, is one reason its overall capacity factor is so low (around 70% as I recollect). Another is that France’s nuclear plants are also cycled to follow daily load.

      Some more data of interest:

      In June 2016 France exported (numbers approximate):

      2GW to UK
      2GW to Germany
      2GW to Belgium
      1GW to Spain
      3GW to Italy
      For a total of 10GW of exports

      So far in November 2016 France has exported (numbers again approximate):
      0GW to UK
      0GW to Germany
      0.5GW to Belgium
      0.5GW to Spain
      And has imported 2GW from Italy
      For a total of 1GW of imports

      There have been no significant power interchanges with Switzerland since October 2015

      Italy is the big loser.

      • robertok06 says:

        “Italy is the big loser.”

        Yep! The MWh on the market has gone up considerably in the past few days…
        This is just a small glimpse at what will happen STEADILY, every day of high consumption, when the green dream of shutting down 33% of the French nukes will materialize, after 2025.

  6. wolsten says:

    How much reliance will the UK have on Short Term Operating Reserve this winter, mostly provided by small diesel generating sets?

  7. gweberbv says:


    you asked for spare capacity. Here is the installed capacity in Germany:
    Some units are probably mothballed, in particular gas plant.

    But spare capacity in Germany or outher countries is not helpful if transmission capacity is a bottleneck. This is defenitely the case now between France and Germany.

    • Euan Mearns says:

      Thanks Gunther, its very interesting. Germany has not reduced its thermal capacity apart from closing down some nuclear. can you please explain to me the rationale behind the UK closing down it thermal capacity and building inter connectors instead to Germany and depending on imports. Why is that better for the UK than having thermal capacity on our own soil?

      • Alex says:

        This is a text book case of dumping. The electricity is subsidised and can then be exported at marginal cost – ie about zero, thereby destroying neighbouring energy markets.

        As with Chinese steel and solar panels, you can one of two things about dumping:
        1. Ban it, or sue, or impose tariffs.
        2. Accept it – if someone gives you something below cost, exploit it.

        The problem with 2. is that they’ll only give it away some of the time.

        • Germany’s neighbors, in particular Poland, the Czech Republic and the Netherlands, were so upset about German power exports screwing up their grids that they complained to the EU and succeeded in getting the renewables subsidy system replaced with the current auction system. They are also said to have installed phase shifters to block German exports altogether, but I don’t have details. More at:

          • OpenSourceElectricity says:

            the phase shifters are present all over well designed grids, also inside the german grid, to allow management (manage power flows) of interconnected grids Those phase shift transformes have been missing in the sovjet style grids in poland and the czech republic, allowing power flows from north to south germany making uncontrolled trips threw poland and czech republic, for which the grid operators there also did not receive payments according todays regulations.
            This is the cause why german utilities and polnish utilities together build the PST’s at the border to prevent uncontrolled circular flows.
            This has nothing to do with regular imports and exports of power. But in Post fact area facts do not seem to matter, so it seems I have to repeat this endlessly.
            The netherlands are building additional capacity towards germany to get better access to cheap power from there. These additional interconnection capacity is also the base for additional interconnectors from UK to belgium.
            Why is it so hard to understand that cheap power is welcome everywhere, while uncontrolled (circular) power flows are not?

      • OpenSourceElectricity says:

        I can not explain the politics in UK, but germany as well expands its interconnector capacity in all directions. The direction where expansion is most difficult are poland and france.
        Beside this the responsible people in german grid management and utilities are people who regular wear belts and suspenders in parallel for safety reasons, and if possible hold their trousers with hands too.
        Which causes them to try to get some GW mothballed capacity above maximum demand even in worse case scenarios.
        This costs a little extra money, but allows to sleep more quiet.
        And a mothballed coal power plant which opperates 100 hours in 5 or 10 years does not really emitt substantial amounts of CO2.

    • jmdesp says:

      No, the nature of the bottleneck between France and Germany is different and is not relevant here.

      Germany now has almost 90W of cumulated wind and solar generation capacity.
      Even if that total is never reached by far, during peaks of generation it still could very realistic become higher than 100% of demand. And as fossil power can’t be switched off because it will be needed as soon as the renewal generation goes down, Germany now frequently can have 20 GW or even more of generation capacity it desperately needs to export somewhere. As a result as I’m writing this, power price in Germany is around 27€ while all the rest of Europe except Netherland is between 50 and 55€ (Spain is above).
      This is the bottleneck that is currently seen, there’s not enough capacity to export all the power to France that Germany would want.

      But here however the question is if France during a cold spell could receive as much power from Germany as it needs. Currently RTE is making sure in December it will be able to import up 4,2GW from Germany if needed, together with 2GW from Belgium and 1,4 GW from Switzerland. ( )
      This should be enough to handle most situations. As the charts you referenced shows Germany has currently around 105 GW of on-demand generation capacity (comprising fossil, hydro and biomass) whilst it’s peak of demand are rarely above 60 GW. It should be able if needed to provide as much as France requests.

  8. Rob says:

    Readers will be aware that the idea that the UK is short of power generation capacity are being
    contradicted by green energy groups promoting the idea of a more flexible approach instead.

    Attached E3G document suggesting flexibility with greater storage and demand side measures up to 15GW of electricity can be displaced.

    The figure of £10 per MWh to cover costs of renewable integration seems very low

    It’s easy to dismiss these reports as nonsense but they seem to be government policy

  9. jmdesp says:

    @Euan Mearns : It’s rarely economically efficient to do as Germany does and have a very large park of fossil capacity that is rarely used. However it has long been the German option, quite unique in Europe as for example France even though it’s peak of demand are higher than Germany has by quite far a smaller total generation park. According to a document I remember reading, the utilities in Germany have long been financially rewarded for building new capacity, even if rarely useful.
    As a result to be honest, Germany is Europe last resort generator, with many fossil units that it can bring out of reserve in case of exceptional needs.

    • Reports of the existence of an enormous amount of surplus fossil fuel capacity in Germany are exaggerated. According to ENTSO-E Germany’s reserve margin in the winter of 2012/13 was minus 0.6%, and things haven’t changed much since then.

  10. Bernard Durand says:

    Energy policy has now become in France a great game of bluff. A part of the nuclear fleet is normally stopped for maintenance during the warm season, to be restarted during the cold one.This time ASN has decided to inspect before restarting a number of reactors, and also has asked for stopping some reactors which were in operation, for a problem that some observers believe to have been created by ASN from nearly nothing for political reasons: the problem consists of an accumulation of carbon in the steel of the reactor, that they say is not normal and could be potentially dangerous. Note that these reactors had no problems sofar.
    Also note that if ASN authorizes the restarting of all these reactors, EDF will become above suspicion to run a fleet of very dangerous reactors, as the Greens say every day.
    As jmesdp says, Germany has now so high wind and solar capacities that it tries to sell at broken prices its production in excess when there is too much wind or solar. It is interesting for EDF and many others to buy this production at such attractive prices. This makes the game of bluff even more complex.

  11. ristvan says:

    I read French so read the most recent 3 ASN reports. The main problem is unreported / undocumented degree of actual carbon segregation in steam generator head forgings. The general root cause goes back to poor QC of the steel ingots used to make these forgings, because that is where carbon segregation occurs if the ingot is not carefully produced and cooled. The French don’t know if it is mainly ‘only’ a paperwork problem, or if corners were cut sourcing lower cost more carbon segregated ingots back in the 1970’s 1980’s. Only way to find out is inspection of the result.
    There is a large metallurgical literature on prevention, detection, and consequences for carbon steel rolled sheet, bar stock, and forgings. I read a DOD document from the 1970’s dealing with the forging of cannon barrels and shafts (ship, generator) because carbon segregation results in mechanical weakness in those ‘stretches’ that can propagate into fatigue microcracking or worse. The DOD report was about how much carbon segregation was permissable, and what barrel thickness saftey margins were needed to cope with inevitable variation within the permissible maximum amount of carbon segregation.
    What started the French old nuc inspections was that one of the two reactors at Flammeville (an old reactor from the 1970’s) actually sprang leaks in its steam generator head. Very not good. Same class issue that caused San Onofre to shut. Rebuilt the steam generator due to fatigue at a cost of over $500 million. New one had corrosion and fatigue problems after just one year, and a third rebuild wasn’t viable. The leaks at Flammeville were traced back to root cause carbon segregation, resulting local mechanical weakness, and resulting fatigue microcracking over time.
    So while Greenpeace may be jumping all over this for the antinuclear propaganda value, the underlying potential safety issue is real and the imspections necessary in my opinion. Apparently the units inspected so far are OK, but another 5 have just been ordered shut for inspection.

  12. oldbrew says:

    The situation with Germany and ‘exports’ to Poland and the Czech republic was more a question of re-routing, to get the power from northern to southern Germany when their own internal (German) transmission lines do not or did not have the necessary capacity.

    As NTZ puts it: ‘The problem with this re-routing is that Poland and the Czech Republic now often find their power grids critically and unpredictably overloaded, and thus have decided to install equipment to keep German electricity out when certain levels are reached.’

    The background seems to be that most of the wind and coal power is in the north, while the on-the-way-out nuclear stations in the south have to be replaced with something. States like Bavaria object to ugly transmission lines and wind turbines disfiguring their nice countryside.

    • Hugh Sharman says:

      @Oldbrew, with due respect to notrickszone, its stuff is mostly propoganda, dressed up as “science”.

      However, this story is basically true. There is a need for phase-changing transformers at cross-over points around the German grids, to deal with the exported instability caused by the Energiewende.

      I offer technically minded readers the following original sources: and

      When and if these considerable investments are actually used, the effect on the stability of the German grids will be profound. Grid stability in Germany remains heavily dependent on balancing its system by constant exports/imports of power from its neighbours.

      A future story for Roger to which I look forward to reading! 😉

      • Hugh: I’m working on something like this, but it ain’t simple. One thing that is apparent, however, is that Germany is two countries from the power supply/demand standpoint. Northern Germany generates more power than it can use but Southern Germany – owing to Merkel’s ill-considered post-Fukushima nuclear plant shutdowns and the lack of NS transmission capacity – has a deficit which is progressively getting worse:

        According to BNetzA, Southern Germany can expect a potential negative balance of up to 5,717 MW by 2018.

        I don’t know whether this number allows for loop flow curtailments through the Czech Republic. Any idea how large they might be?

  13. ralfellis says:

    Why is France importing energy at 3am, when it has the surplus to export in the peak evening? Do they have lots of pumped water storage systems, and are using UK energy to recharge them??


  14. jim brough says:

    What does this mean to the public

  15. Pingback: The European Blackout Risk | Energy Matters

  16. Bernard Durand says:

    @Ristvan the price of a steam generator is around 50 millions Euros, not 500.

Comments are closed.