It is commonly said that the lifespan of a power plant is 40 years. After this period, problems may arise, and the plants are then considered old. Thus, many questions may arise: should they continue to operate, should they be refurbished or replaced, or should they be closed drastically?

This is the case for France, which has an aging nuclear fleet that should reach this deadline by 2025, without really having anticipated the problem that would arise. Opinions differ on this subject between the different solutions, which have their advantages and disadvantages.

 If the question arises, it is because nothing prohibits it

Indeed, the French Nuclear Safety Authority (ANS) does not set a maximum lifespan for the operation of a power plant, but simply issues an operating license, after a careful study of the reactors, valid for the next 10 years before having to make one. Extending the life of a plant beyond the recommended 40 years is even possible, if a certain number of criteria are met, meeting the safety conditions set for new reactors, and even advisable to some extent.

Indeed, extending their lifespan avoids new heavy investments to replace them, while management investments are much lower, even with the new safety standards and the related adjustments. As an indication, the total cost of these improvements is estimated at 400 million €, i.e., 10 times less than a new EPR reactor for example, presented as a potential alternative. Moreover, the profitability of the power plants is complex and is amortized over 25 or 30 years, so extending them to the maximum is very interesting financially.

Beyond these undeniable economic advantages, in terms of security of energy supply, extending the life of power plants can also be an asset, especially in the energy transition, whether the new means of producing energy are nuclear or not. So, the scheme would be as follows: extend the life of existing power plants, before slowly replacing them with EPRs and then potentially with new generation reactors such as SMRs.

The technical aspect of extending power plants.

So, according to the experts, although a power plant is initially designed to operate for 40 years, it can be used for up to 60 years, but opinions differ once again, as with the Nuclear Observatory, which fears accidents or dangers if these aging power plants are used too long. The main risk lies in the weakening of the reactor vessel. Nevertheless, some components are not replaceable.

The irreplaceable components.

Replace them in case of obsolescence. But the particularity of the French nuclear fleet is that it was built by a single manufacturer over a short period of time. Thus, this generalization poses a serious problem: a problem on one of them could also be generalized on those of the same level, even though the conditions of the location of these plants play a lot on the evolution of its components, in particular because of the variable weather, the environment, or the operating methods.

Old age means danger?

First, it is important to know that in terms of numbers, the oldest nuclear power plants do not have more problems than the most recent ones. Nevertheless, malfunctions related to old age are among the most numerous of those reported. Opinions also diverge on this point between the anti-nuclearists who necessarily validate the hypothesis that an old reactor would be more dangerous, while those in favor advocate the opposite logic, which is that an old reactor has proven its value and safety in the past, having validated several ten-yearly visits. A simple way was used thanks to the Ines scale, allowing to compare the importance of the different anomalies experienced in the power plants. There is no correlation between the age of the reactor and the number of anomalies or their severity. The number of anomalies stagnates even for reactors that are about to reach 40 years of age, and the severity of accidents decreases over time as the reactors age. For the NGO Greenpeace, nuclear power plants were designed for a period of 30 to 40 years and so the actors are plunging into an unknown area and may well regret it.

A temporary extension.

Indeed, between the new EPR reactors and the SMR modular mini reactors, the future of this sector is assured, but these technologies will take time to be implemented. The testing and certification phases of the latter are much longer, and their efficient commissioning is not expected before 2030. In the meantime, France will not be able to afford to abandon nuclear power, which is so important for its electricity production (about 70% of total production comes from nuclear power). The solution therefore lies in a temporary extension, to compensate for this lack of anticipation and to bridge the gap between the end of the power plants reaching their forties and the arrival of new generation reactors. This will effectively facilitate the transition and make it gradual rather than closing the plants abruptly and replacing them. Moreover, even Greenpeace advocates the development of new ERPs, which they consider safer.

The details about this extension.

To extend these old plants, changes will have to be made as previously mentioned. Indeed, the ANS has authorized the extension of some plants for 10 years, while encouraging EDF to adjust for the new standards. The conditions set for their proper operation beyond the fourth ten-year review are intended to ensure their safety and to be sure that the patina of time is not felt, particularly regarding potential accidents and their severity. In addition, in terms of external hazards, the modifications must ensure that the plants are still capable of withstanding them, particularly in the event of an earthquake, for example, or internal fires. Thus, a refurbishment is not on the agenda because it would be too costly and useless in the face of the future arrival of new generation reactors but making improvements to the reactors already in place has been the solution chosen to promote an effective transition by reducing costs.

Although opinions differ on the future of the French nuclear fleet, the solution of extending it by a few years seemed to be the most appropriate for the current situation, to compensate for the lack of anticipation but also to prepare for the future arrival of the 2.0 nuclear industry.