By Christian J Meier
France’s nuclear power plants are weakening: for the whole of 2022, they will be supplying significantly less electricity than usual. The electricity export nation France imports electrical energy from Germany in phases.
That’s not all: the situation could become “absolutely critical” if there is a cold winter, says Mycle Schneider, an international nuclear policy analyst who lives in France. Almost a third of French apartments and houses are electrically heated.
The power bottleneck in France made headlines especially in the summer, as the reactors were also throttled because of the heat. But the misery continues. During October, French reactors produced less than 30 gigawatts instead of just over 40 gigawatts this month, according to market analysis firm Kpler. Improvement is not in sight. At the beginning of November, the energy company EDF revised its previous annual forecast for 2022 downwards.
The critical lines are actually intended as safety precautions
A major reason for the ongoing power shortages are cracks in safety-relevant pipelines in several reactors, which lead to shutdowns, inspections and costly repairs. The first cracks were discovered in December last year in a reactor at the Civaux power plant. As a result, three identical reactors were shut down. “As a precaution,” praises Mycle Schneider. Two of them later also showed cracks. Inspectors soon discovered more cracks in another type of reactor, of which France has twelve. These were not all shut down as a precaution, Schneider notes. For him, this is a sign that the operator EDF is cutting back on security in favor of security of supply.
In order to classify Schneider’s thesis, it is worth taking a look at the phenomenon. The reactor vessel is filled with water. This is heated by the energy that is released during the nuclear reaction. The hot water flows through a pipe circuit to a heat exchanger. After dissipating its heat there, it flows back into the reactor vessel. Because it transports the heat away for further use, it is called cooling water.
A leak in the reactor vessel can lead to a so-called loss-of-coolant accident. The reactor would shut down. Nevertheless, heat would continue to be generated by the decay of radioactive fission products. If too much cooling water has escaped from the leak, it can no longer be transported away and, in the worst case, a core meltdown can occur.
To prevent this, another pipe system docks onto the cooling water circuit, through which new cooling water flows in the event of a leak. The cracks have now appeared on this “safety feed-in system”. The Society for Plant and Reactor Safety in Garching writes on its website that this is relevant to safety. If the cracks were to exceed a certain size during operation, the line could break and a loss of cooling water accident would occur. In a way, security is proving to be the Achilles’ heel.
EDF removed affected pipe sections to examine the cracks in the laboratory. Accordingly, they are caused by mechanical stresses, such as those caused by temperature differences, especially near weld seams. The design of the piping systems, which differs between different types of reactors, also plays a role. The cracks were less than one to six millimeters deep, about one-fifth of the total thickness of 30 millimeters. In addition to the four confirmed cases of cracks, indications of four other cases have been found so far, only one of the reactors has given the all-clear. By 2025, EDF wants to test all reactors for cracks using a specially developed ultrasonic method.
The majority of reactors are hardly vulnerable, says the nuclear authority
Is the French fleet running at increased risk until then? No, says the French nuclear safety authority. EDF’s testing strategy is “reasonable,” she wrote in July. Only two types of reactors are prone to cracking, mainly because of the design of their safety injection system. These would be examined with priority. The other types, which make up the majority of piles, are “little to very little” susceptible to this type of crack.
However, Mycle Schneider does not believe that the crisis is over. It is “much more far-reaching”. The basic problem is a “degraded” power plant park. “The cracks only came on top,” says the nuclear power expert. “Electricity production from French nuclear power plants has been falling steadily for several years,” emphasizes Schneider, who publishes annual statistics on the global nuclear industry. The historically highest annual production in France was 430 terawatt hours in 2005. In 2020 it was almost a hundred terawatt hours lower. This minus alone is significantly larger than the annual nuclear power production in Germany. According to forecasts by EDF, this year will fall well short of this minus record.
According to Schneider, maintenance that took longer than planned would have led to many unplanned total failures in electricity production. “The operator has lost control of the means of production.” A strict austerity course for 20 years – there was often a lack of spare parts – and a scarce staffing would have contributed to this. The operation of the French nuclear power plants is now increasingly at the expense of safety, he criticizes. Schneider cites a kiln in Cattenom as an example. Despite identified cracks, EDF wanted to restart it quickly and would not repair the damage until a planned shutdown next year. However, the group did not get through to the supervisory authority, which requires immediate repairs, which extends the shutdown until at least the end of February 2023.
The current weakness of French nuclear power plants could therefore be repeated. In February 2022, the French President called the use of nuclear power in France a “great adventure”. He actually wanted to whet the appetite for a “renaissance” of this form of energy. Nine months later, another interpretation suggests itself.