2024-02-26 10:30:40
A spin-off from the CEA, HEXANA is an industrial start-up founded in June 2023 and winner of the France 2030 call for projects “Innovative Nuclear Reactors”.
Cet call for projects aims to promote the emergence of new French players capable of designing fourth generation nuclear reactors, allowing, among other things, to improve the management of the life cycle of radioactive substances.
The specificity ofHEXANAwhich wants to industrialize advanced modular reactors (AMR) with cogeneration, is illustrated by the career of the three engineers behind the project.
Sylvain Nizou, CEO of HEXANA, is an engineer who has worked for a long time in the energy field. He is a specialist in energy issues and in particular questions of CO2 capture and valorization, but also in the decarbonization of industry in general. Based on the observation that innovation would ultimately make it possible to develop efficient CO2 recovery technologies, hydrogen production or new fuels for the aviation sector for example, the problem for the latter consists of benefiting from a access to considerable quantities of carbon-free energy, in the right form and continuously.
Paul Gauthé, CTO of HEXANA, is also an engineer, an expert in the fast neutron nuclear sector, and worked on the operation of Phénix and on the ASTRID project (prototype of a fourth generation sodium-cooled fast reactor). Finally, Jean-Baptiste Droin, CIO of HEXANA, is also an expert engineer in safety, design and operation of advanced nuclear reactors and their coupling to new uses serving industrial needs.
It is from the meeting between the understanding of the energy needs necessary for the decarbonization of industry and the fourth generation nuclear technologies capable of meeting these needs that HEXANA emerged.
Sylvain Nizou explains to us what the advanced nuclear reactor project carried by HEXANA consists of, and how it can specifically respond to the decarbonization challenges of the industry while offering a model for the sustainable development of nuclear energy.
Engineering Techniques: What are the concepts underlying the technological solution developed by HEXANA?
Sylvain Nizou: HEXANA is working on the design of a sodium coolant fast neutron reactor system, known as RNR-Na, associated with an energy storage device, which makes it possible to supply heat on demand up to 500 degrees and electricity for industry.
The technology of FNR-Na (sodium-cooled fast neutron reactors) has been known for more than seventy years in the major countries that are leaders in nuclear energy. France operated the Phénix experimental reactor for 35 years, then developed, built and operated the largest FNR-Na in the world – (Superphénix), thus demonstrating that it was possible to develop FNR technology on an industrial scale and in major power.
Then, the ASTRID project aimed at developing a fourth generation reactor demonstrator made it possible to relaunch this FNR-Na sector, to renew skills, calculation resources, and to get up to speed with a view to industrial deployment.
If the ASTRID project did not continue in 2019, everything did not stop there: analyses, international strategies, and designs of new reactors were developed based on the knowledge accumulated on the ASTRID project, and continued since 2019.
We therefore worked, for three years within the CEA, on a new concept, leading to the creation of HEXANA. There is therefore a form of continuity without the desire to remake ASTRID, since HEXANA benefits from all the work carried out upstream by the nuclear industry on FNR-Na for decades.
Our desire is to develop an innovative object, an advanced SMR (AMR), with all the promises that this conveys in terms of construction time, cost control, competitiveness, and much wider use compared to traditional reactors intended to produce electricity for a national grid. And in particular this ability to produce heat at high temperature and electricity directly and at the same time in a flexible manner, according to needs: the industrial world needs electricity but also heat. And currently this heat is massively generated using fossil fuels. It is therefore very relevant to extract this heat from the RNR-Na, with a recovery which is between 95 and 98%.
How is the heat produced stored?
The heat is stored in molten salts, it is a very specific technology borrowed from the world of concentrated solar energy, which we are the only ones to develop in France and to integrate into an AMR. This heat storage, which offers flexibility in the power delivered, will power either a turbine to produce electricity, or directly the industrial sector which needs this heat.
What fuel is used?
The reactor uses MOX nuclear fuel for its operation. It is a mixture of plutonium and depleted uranium. It is manufactured from materials resulting from the reprocessing of spent EDF fuel and co-products from the enrichment sector. This approach makes it possible to initiate the closure of the nuclear fuel cycle and reduce the dependence of the nuclear sector on imported mineral resources.
What are the challenges in terms of innovation?
We choose to capitalize on past achievements and innovate where necessary. There is an immense challenge in the transition to the industrialization of a standardized modular FNR-Na reactor: there are new components, a completely new design and an industrial organization which the nuclear sector does not yet have. experience.
But we are betting not to innovate on the aspects of the project which work and which have already been validated by the safety authorities: an integrated design reactor like Phénix and Superphénix, a qualified MOX fuel, steels also qualified for all the components. We thus use certain mature technological bricks, which we integrate into our reactor, which produces a power of 400 MW thermal. It is possible to convert this thermal power into electricity, with an efficiency of 42%, or around 300 MW of electricity for a pair of reactors providing a total of 800 MW of thermal power.
We decided to combine these reactors in pairs (or four depending on the customer’s needs) to be able to ensure continuity of service. When one of the reactors must be refueled or put into maintenance, the other provides at least half of the energy requirement. This allows the customer to benefit from a continuous supply of energy, and gives us the possibility of pooling certain systems to save on construction costs. We only innovate where necessary to move quickly. Firstly because this allows us to concentrate our engineering efforts on the challenge of industrializing a modular object that can be mass-produced, but also because we do not have the R&D tools to do so. irradiations of new materials, new systems. We cannot therefore commit to qualifying new objects, which requires a lot of time. However, once the first reactors are started, we will be the first to have R&D capacity to improve our technology and increase our competitiveness with our lead series.
You also rely on historical players in the nuclear industry.
Indeed. We are part of an existing ecosystem, with a supply chain which, even if it needs to be strengthened and renewed, already exists: we work with EDF, with the CEA, with Framatome, ORANO, BOUYGUES CONSTRUCTION and EGIS, among others , to promote this prized know-how and historic intellectual property.
By capitalizing on past achievements, even though we have enormous challenges with new components such as exchangers, pumps, designs, manufacturing and industrialization processes, we are able to move forward quickly. Our first industrial production head is planned for 2035, and we do not need to go through a prototype and a nuclear demonstrator. We are moving directly to an industrial series leader, which will save us time compared to other players in the sector who must have all the new nuclear elements of their system approved and first and foremost go through nuclear prototypes or not. -nuclear.
Many international nuclear players are today interested in FNR-Na…
Indeed. Today, all the major nuclear countries are in the race for RNR-Na. Ten years ago, the United States launched TerraPower, which is developing the Natrium project, whose heat storage system in the form of molten salts is quite similar. This is not an SMR, but a 350 to 500 MW electric reactor not particularly intended to operate in cogeneration, so we are not in competition with them.
China has an experimental reactor and is currently building two 600 MW thermal reactors. India is also developing FNR-Na just like Japan.
Finally, Russia remains the leader in this niche: it today operates an experimental reactor, and two industrial reactors of 600 and 800 MW electric, supported by a MOX sector and continues to develop other power FNRs.
We are therefore not the only ones in this niche, but today we have skills and knowledge in France on these RNR-Na that the whole world envies us.
How do you work with manufacturers who could use the solution you are developing?
Our particular heat storage and downstream energy conversion system is designed to be specifically adapted and flexible to the different uses identified. This is work that we carry out in very close proximity to the industrial world. We are undertaking use case studies with players in the chemical, aviation, maritime, steel, cement, hydrogen and synthetic fuels sectors. We work with them to identify how HEXANA can meet their needs. What is their rate of consumption, the share of heat and electricity they need? At what temperature do they use heat? Is their electricity consumption continuous? Are there significant variations in consumption? Can such a system offer other solutions such as CO2 capture or seawater desalination?
We also address, in terms of customers, the electricity network in a global way: in the projects that we imagine, the fact of being able to resell electricity to the network when it is most needed represents real value, a all the more so in a context where intermittent renewable energies will take an increasingly important place in energy mixes requiring flexibility capacities such as those offered by the HEXANA system.
At this level, our energy storage system is a service provided to the network, very complementary, in favor of the strong integration of renewable energies and the reduction of the use of fossil fuels.
Comments collected by Pierre Thouverez
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