Lately, the nuclear sector has seen a trend towards small modular reactors (SMRs), sometimes developed by start-ups. Numerous light water SMR concepts are flourishing around the world, based on a wide range of technologies and outputs. AMRs (Advanced Modular Reactors) are equivalent concepts of 4th generation: fast sodium, molten salt or high-temperature reactors, with a longer deployment time than SMRs.

Jean-Michel Ruggieri

Maxence Cordiez

Stéphane Sarrade

a trend towards small modular reactors (SMRs)

, sometimes developed by start-ups. Numerous light water SMR concepts are flourishing around the world, based on a wide range of technologies and outputs. AMRs (Advanced Modular Reactors) are equivalent concepts of 4th generation: fast sodium, molten salt or high-temperature reactors, with a longer deployment time than SMRs.

outputs ranging from a few MW to a few hundred MW

. With different timeframes, they target different customers and uses: isolated communities, cogeneration, replacement of medium power coal plants, etc. These 

 developed by a small handful of engineers and communicators, most of which will probably never materialise, 

, such as the SMR on board the Russian barge Akademik Lomonosov.

France is part of the game. EDF, CEA, Technicatome, Naval Group and Framatome are jointly working on an SMR model for the end of the decade.  

This article will present the stakes, the interest, but also the issues

 linked to the design and deployment of SMRs to achieve carbon neutrality while preserving our energy security.

As recently outlined by the French electricity grid operator RTE in its Energy Futures 2050, 

 to replace fossil fuels. Today, electricity accounts for 15 to 25% of the final energy mix, depending on the European country (25% in France). However, electricity is probably the easiest energy vector to decarbonise. This is why its share in the final energy mix will have to increase to achieve carbon neutrality (up to 50-60% in France according to the national low carbon strategy).

 the European Union needs to rely on all the low-carbon energies 

at its disposal, including the first among them (in Europe at least): 

many limitations in the current reactor catalogue

, ranging from medium to high power. For instance, large reactors are tailor-made for their location and power grids, and their deployment can be limited by the cost of capital. It is indeed a challenge for many countries (let alone private actors) to finance large 

multi-billion euro reactors, which can take up to 10 years to build

 (thus delaying the start of the return on investment).

Another limitation of these reactors is that, while they are particularly well suited to massively produce competitive electricity on demand, they are less suited to cogeneration: it would be less convenient to locate a 1650 MW EPR next to a conurbation for the cogeneration of electricity and district heat, for example.

The idea of designing low power modular reactors was born to complete the current offer. The 

 (ranging from a few MW to a few hundred MW) in which most of the components are previously assembled in factories to minimise the number of operations to be carried out onsite during the construction. This makes it possible to 

 of slippage by simplifying onsite operations.

These smaller (and cheaper per unit) reactors would be 

. Smaller, they would also be better suited to cogeneration applications closer to the place of consumption, which is of interest in certain regions: electricity and urban heat for Finland, electricity, industrial heat and hydrogen for Poland, etc.

Indeed, without massive production of low-carbon electricity, available regardless of external conditions, the prospects for the deployment of a European hydrogen industry appear compromised. The 

available hydraulic and nuclear capacities

 to implement in some countries than large-scale reactors, which remain economically relevant in countries that can finance them and absorb their output. SMRs can work in synergy with other low-carbon sources of electricity such as wind and solar PV to provide electricity at any time of the day, in any season and under any weather conditions. Their smaller turbine size allows for greater load-following responsiveness than large reactors, and the increased capacity of these reactors to be located across the country can help stabilise the electricity grid. They 

offer the opportunity of moving away from a long-term dependence on coal and fossil gas

design and production of small reactors is not new

. Many countries, including France, the UK, Russia, the USA and China, have been using them for years to power submarines, aircraft carriers and icebreakers. While it is clear that civilian SMRs cannot embody military technologies, this experience enables the incorporation of major innovations. Most of the concepts, such as the French Nuward or the American NuScale, have chosen a primary circuit integrated into the reactor vessel, which eliminates the risk of a primary breach. Nuward has also chosen plate steam generators, which makes it the most compact concept.

The reduced power of these reactors also allows for a 

. This means that in the event of an incident or accident, the reactor remains in a safe configuration for a significant period of time, without human intervention or external power supply.

 (in the plural) for SMRs are becoming increasingly clear: 

 with cogeneration needs, etc. Whether it is the Americans, Russians or Chinese, all the major nuclear reactor designers are deeply involved, with different approaches and concepts. The competition will be tough. In Europe, the United States has kicked off by organising an event to promote its SMR technologies in partnership with the European Commission on 21 October 2019. In this strategic area for its independence, its sovereignty and its climate objectives, the European Union must be proactive. We must develop European technologies, with the intellectual property and the manufacturing industry for critical components.

. This would be the case if European projects (including Nuward) were not to be supported even if nuclear power has been recognised at its true value in the taxonomy of “sustainable” investments that the Commission is currently putting in place.

, this is not without reason: to a certain extent, making a reactor larger allows for 

. Whether a reactor is medium or large, the certification process, public enquiries and construction will be comparable. The more powerful the reactor, the more the costs can be amortised over a large output. In addition, the larger the reactor, the more efficient it is in its fuel use, i.e. the less fuel it consumes and the less waste it produces.

Ensuring the competitiveness of small reactors is therefore not an easy task. 

 One of the challenges is therefore to achieve true modularity, making the most of factory production to reduce the number of actions to be carried out on the construction site.

: SMRs will only be competitive if they are produced in large numbers and if the fixed costs (component production plants, design and certification processes, etc.) are amortised over a large number of units. The use of conventional pressurised water reactor fuel is also a way to take advantage of the available current fuel cycle infrastructures to limit the development time and cost of electricity produced by SMRs.

This raises a twofold issue. Firstly, whatever the SMR, its market cannot be limited to a single country. Secondly, it is necessary to bring the safety requirements of the various countries where an SMR concept may be deployed as close as possible. The objective is to avoid having to modify the concept in each country, as this would require new engineering studies and the modification of industrial chains, which would make the economic equation for SMRs impossible. 

The discussion between SMR manufacturers and safety authorities around the world should therefore start at an early stage of the design.

How to maximise the chances of success for the European projects?

We should all keep in mind that a continent has to anticipate the future and take advantage of all low carbon energy sources. Therefore, 

we cannot give up all our skills and industry in nuclear energy

, at the risk of being left with nothing if – as we believe – we eventually realise that this energy source is absolutely necessary to achieve carbon neutrality while preserving our energy security.

The European Union must therefore support the emergence of one or more European SMRs. The 

, initiated by France, is today the most advanced and is therefore a good candidate. However, this project cannot remain solely French. It must become a truly European project because the first (and potentially most) examples will serve the European market.

This is why the European Union should also work with the national safety authorities on a 

, which respects both the independence and the autonomy of the various safety authorities while avoiding the multiplication of standards in Europe.

Europe is at an energy crossroads. We need to 

ensuring the security of electricity supply

, which is threatened in the next few years by the closure of many European dispatchable power plants. At the same time, the price of fossil fuels is soaring in the face of chronic underinvestment in the upstream oil and gas industry over the past several years and continued strong demand growth in Asia. 

 to answer to all these constraints, not only to produce electricity, but also urban and industrial heat, hydrogen and even to desalinate seawater. The needs are huge and it is 

now time for Europe to position itself on the SMR and AMR technologies

 it will need, in order to have domestic technologies that will provide qualified jobs and guarantee its strategic autonomy. The window is closing and if we do not act quickly, we will once again be dependent on imported technologies in a strategic field.

This article is also published in French on 

Energy Voices is a democratic space presenting the thoughts and opinions of leading Energy & Sustainability writers, their opinions do not necessarily represent those of illuminem.

Small Modular Reactors are a key technology to decarbonize our economy

Jean-Michel Ruggieri is Small Modular Reactors program manager at the 

French Alternative Energies and Atomic Energy Commission

. At the CEA since 2000, he headed successively the Neutronics, Nuclear Physics and Severe Accidents research laboratories and the Innovative Systems Studies Service in Cadarache. 

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Jean-Michel Ruggieri

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