Two opposing models are facing off. On the one hand, high-power reactors such as EPRs, which rely on the centralization of production with high-power units; on the other hand, modern, small reactors with an electrical capacity ranging between 10 MW and 300 MW.
For several years, although divisions persist, Swiss public opinion has evolved considerably on the question of nuclear energy. A poll conducted by Tamedia, published in late September 2024, revealed that 53% of respondents support the construction of new reactors in our country. It must be said that global demand for electricity increases every year, driven by the electrification of uses as well as by the development of digital technologies and generative artificial intelligence.
While renewable energies, such as solar and wind, are booming, they nevertheless pose a major problem: they do not guarantee linear production. The question of balancing supply and demand for electricity is therefore not resolved, despite advances in smart grids, battery storage capacities, or pumped-storage hydroelectricity.
To compensate for the intermittency of renewables, nuclear could therefore be part of the solution for the energy transition, on the same level as hydropower, because it provides a baseload and decarbonized energy, thus supporting the development of solar and wind.
Nuclear is by no means free of flaws. Very high construction costs make it a highly capital-intensive energy, requiring often complex safety systems. In addition, it is not a renewable energy, because uranium must be extracted from mines, and the question of treatment as well as the storage of waste remains electrical.
According to figures from the Federal Office of Energy (SFOE), and contrary to what one might think, nuclear energy production is growing strongly worldwide. In March 2024, 57 new plants were under construction, representing an additional capacity of 59 GW (bringing the total to 373 GW installed).
Two antithetical models now face each other. On the one hand, high-power reactors such as EPRs rely on the centralization of production with high-power units, on the order of 1,600 MW. For example, the Flamanville EPR (France) accumulated numerous delays, and its cost was recently estimated by the Court of Audit at €23.7 billion, against an initial estimate of €3.2 billion in 2003.
On the other hand, Small Modular Reactors (SMRs) are modern reactors whose electrical capacity ranges between 10 MW and 300 MW. Besides their small size, they are designed as modules, which can be mass-produced in factories and combined with other existing units, giving them greater flexibility.
According to the Nuclear Energy Technology Monitoring, published in July 2024 by the SFOE, the production costs of SMRs are much lower than those of large reactors, thus offsetting the economies of scale obtained at large plants during the production phase.
The cost per kWh produced by SMRs should therefore be in a similar order of magnitude to that of large plants, although many parameters influence their cost price, notably delays, construction costs and changes in interest rates.
For Mathieu Hursin, lecturer and researcher at the Laboratory of Reactor Physics and Systems Behavior at EPFL, “SMRs also have the advantage of being able to power isolated areas disconnected from the grid, currently dependent on gas or oil.”
It is therefore no coincidence that the first country to use this technology was Russia, with the Akademik Lomonosov, the first floating barge equipped with an SMR, moored at a port in the Russian Far East. Its commercial operation began in May 2020, producing energy thanks to two 35 MW reactors each.
“The development of certain reactors, notably graphite ones, makes it possible to reach temperatures on the order of 900 degrees, thus opening the way to the production of decarbonized hydrogen thanks to nuclear technology,” explains Mathieu Hursin, lecturer and researcher at the Laboratory of Reactor Physics and Systems Behavior at EPFL
SMRs are currently under construction in China, Argentina, Canada, South Korea and the United States, representing more than 80 units intended for commercial use. These reactors serve various applications, such as electricity or heat production, integration into hybrid energy systems, or seawater desalination.
According to the researcher, “the wide range of possible uses goes beyond electricity production alone, making this technology particularly interesting for large industries.” He adds that “the development of certain reactors, notably graphite ones, makes it possible to reach temperatures on the order of 900 degrees, thus opening the way to the production of decarbonized hydrogen thanks to nuclear technology.”
Other advantages concern the adaptation of safety procedures, which rely on passive systems exploiting physical phenomena such as natural circulation, gravity or self-pressurization. These devices, less costly, increase the safety margin by reducing the risk of radioactive leakage into the environment.
Furthermore, for some countries that do not have the critical size in terms of needs to host a large nuclear plant, it is difficult to raise the necessary private investments. Reducing costs could thus remove this obstacle.
Regarding the attractiveness of SMRs, Mathieu Hursin specifies: “The first reactors in production always present a higher financial risk, although the technology itself is well mastered. The issue lies more in the design and production, because current SMRs are based on third-generation technologies, for which we have acquired some experience, although the level of mastery is lower than on the current technology.”
The Alpiq group also believes that the first SMRs will use third-generation light-water technologies. Although fourth-generation prototypes now exist, they have not yet been developed to maturity for commercial production.
According to the EPFL researcher, however, SMRs have limited interest for a country like Switzerland, where the electrical grid is dense. Some concepts could nevertheless be useful to reduce the duration of waste storage or for specific industrial applications requiring very high temperatures.
On the other hand, this model could develop in large countries less well equipped with electrical infrastructure, or to power industries such as mines and steel mills. The tech giants, whose electricity needs are exploding due to the development of AI, are also interested.
“The first reactors in production always present a higher financial risk, although the technology itself is well mastered,” believes Mathieu Hursin.
From Alpiq’s side, the question of building a new plant in Switzerland is not currently being considered. However, if this were to be envisaged in the future, SMRs would offer an advantage in terms of flexibility in an increasingly decentralized and volatile market.
Although some envisage restarting nuclear energy, it would require rebuilding an entire sector from the ground up, starting with talent training. In Switzerland, a joint master’s degree in nuclear engineering, offered by EPFL, ETHZ and the Paul Scherrer Institute (PSI), has seen its number of students increase since 2017, from 10 students after Fukushima to 30 this year. This center of expertise is therefore highly valued, and some players, notably in France, recruit talents there due to a lack of qualified labor in their own country.
If, for some, the revival of nuclear reflects our inability to move away from energy abundance and to do better with less, for others it represents a necessary path toward the energy transition. Although it is still too early to assess the commercial success of SMRs, climate challenges and the electrification of uses call for an evaluation of all solutions available and increased risk management. In this context, the development of SMRs could be a step in the right direction, but must not overlook the imperatives of energy efficiency and sobriety, to be implemented from today.
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