Could the nuclear power plants currently in operation be able to operate beyond 60 years? The proposal had already been blown by Cédric Lewandowski, executive director of EDF, in charge of the nuclear fleet, but it took a new turn on Monday January 23 with the declarations of the boss of the Nuclear Safety Authority (ASN). “We want to enrich ourselves with experiences from abroad who have accepted that their reactors are over 40, then 60 years old, and even, for the United States, 80 years old”, launched Bernard Doroszczuk on the occasion of his wishes for the press.
“A cultural revolution is potentially brewing, as the American and French models differ so much on the way of analyzing the risk or taking the costs into account. However, the threshold of 80 years has not yet been acquired, far from there”, reacts Dominique Grenèche, professor at Sciences Po and at the National Institute of Nuclear Sciences and Techniques (INSTN). “First of all, we must not believe that we are going to suddenly extend the life of the power stations by several decades”, insists Dominique Vignon, former boss of Framatome and head of the energy division of the technology academy.
The law provides for a safety reassessment every ten years. And this gives the necessary conditions to operate ten more years, not more. Our oldest plants, which reach their 40th birthday, have obtained authorization to operate until 50. And when they do, we will ask ourselves the question of adding – or not – ten more years. In fact, before a plant reaches 80 years, three safety reviews will be planned. “It is not a question of operating longer with less safety, but of determining at an equal level of safety how we can improve the calculation of the physical phenomena at work to go further”, explains Julien Collet, the general manager. Deputy of the Nuclear Safety Authority.
In reality, this deadline is not quite a first. Cédric Lewandowski recalled last week before the National Assembly that “six reactors in the United States have obtained an operating license for up to 80 years and it turns out that our technologies are roughly similar”. In concrete terms, extending the life of nuclear reactors requires knowing the aging of parts that cannot be repaired or modified.
Preparing for the future
In this field, technological progress and the experience acquired by the sector are gradually opening up new perspectives. “There is now a consensus to say that technically a power plant can operate for up to 60 years, assures Valérie Faudon, general delegate of the French Nuclear Energy Company (SFEN). For several years, experiments have shown that the tank and the enclosures – two elements that are impossible to change in a power plant – resist damage better than expected. For the rest, upgrading work is possible without major technical difficulties, assure the experts. change almost all the elements, even the very imposing steam generators, whereas thirty years ago, it was unthinkable”, assures Dominique Grenèche.
Encouraging element: EDF, which is struggling to find welders to build new power plants, would experience fewer labor difficulties for the maintenance of its fleet in the years to come, underline several experts. Even if for the moment, shutdowns for maintenance are stretching out with massive recourse to subcontracting. Certainly, it will still be necessary to develop new inspection technologies, and carry out technical studies that will last several years. “However, I think it is interesting to look into these questions today in order to be able to prepare for the future, believes Valérie Faudon. At the end of the 2030s and the beginning of the 2040s, the first EPR2s will arrive online. But we are going to face very rapid closures of production capacities, because many current reactors will reach 60 years of age at the same time. We must prepare for this now”.
And this is also the meaning of the intervention of the boss of the ASN. If the extension of the service life is not possible, other levers will have to be activated: speeding up the delivery of the next EPRs, working twice as hard on renewables… “The positive point that emerges from this reflection is is flexibility. We are emerging from a period of rigidity illustrated by the objective of reducing the share of nuclear power to 50%, set at the start without any real basis”, analyzes François Lévêque, professor of economics at the Ecole des Mines de Paris and specialist in energy matters.
The climate issue
Finally, one of the main challenges could come from climate change. How to extend the lifetime of reactors in a context where extreme weather events are becoming both more intense and more recurrent? “The management of extreme climatic episodes must be anticipated, both for the fleet in service and for new installations, by integrating the accumulation of potential impacts on a territorial scale”, thus evokes the ASN. What will be the effects of a global warming of 2°C on heat waves in France? French nuclear reactors will eventually have to be able to withstand heat records never before achieved, but also be adapted to future episodes of drought. “We are going to look at the risks of extreme heat because high temperatures can affect the proper functioning of equipment, but also the risk of flooding and ensuring that there is always enough water to ensure the cooling of the systems. safety”, explains Julien Collet.
EDF took the lead. The group ensures that it anticipates levels of climate change 30 or 80 years in advance for new installations. “EDF has integrated higher temperature assumptions in recent years, but we can see that they can sometimes be exceeded, as in 2019, for three power plants located in the north of France”, warns Thibault Laconde, engineer and founder Callendar , a company specializing in climate risk assessment.
It will also be necessary to ensure that the activity of the reactors does not degrade its immediate environment. Plants operating with an open cooling circuit draw water from rivers and discharge it into the watercourse, a technique governed by very precise temperature thresholds. These can force a reactor to reduce its electricity production, or even to shut down, if the discharged water is too warm. Electricity or biodiversity? Another dilemma for ecology.