2024-02-27 10:30:41
Blue Capsule is working on the design of a PRM – a small high-temperature nuclear modular reactor – providing industrial heat at 700 degrees, and using ambient air as a cold source.
Winner of the “Innovative Nuclear Reactors” scheme set up via the France 2030 investment plan, Blue Capsule, founded at the end of 2022, is developing a 150 MWth high-temperature nuclear reactor, based on a sodium coolant. The project couples two mature technologies, in order to combine for the first time the intrinsically safe fuel of high-temperature nuclear reactors, made up of Triso microparticles, with high-temperature liquid sodium (above 700°C) as a coolant.
Edouard Hourcade, President and co-founder of Blue Capsule, and Domnin Erard, architect of Blue Capsule, explained to Techniques de l’Ingénieur what makes the reactor project specific to the start-up, as well as the industrial applications envisaged. .
Engineering Techniques: can you go back to the genesis of Blue Capsule?
Edouard Hourcade : Blue Capsule is a “child” of Astrid, which was the GEN 4 prototype sodium-cooled fast neutron reactor of the CEA, a program on which I worked for 5 years, notably as safety manager. When the Astrid project ended, I was asked to think about ways to use the heat produced directly, and not electricity as was initially planned. The heat produced by Astrid was at 550 degrees: developing reactors at high temperatures, between 650 and 1000 degrees, therefore seemed more suited to the needs of manufacturers.
This also corresponded to a period of nuclear renewal in the world, and many new concepts appeared, so I studied all of this to propose the concept of Blue Capsule, which is a mix between two mature technologies that already exist: HTR and sodium-cooled fast reactors (FNR-NA).
How does this reactor work?
Domnin Erard: The idea behind Blue Capsule is to draw the quintessence of technologies that already exist, namely FNR-NA and HTR, with the objective of keeping the temperature high.
Moderation is done by hexagonal graphite blocks, assembled geometrically. We do not use sodium as a direct fuel refrigerant. We circulate it around the protective envelopes of the graphite, and with its very good refrigeration capacity, it allows us to design a smaller, more compact reactor. This allows us to obtain high temperatures, adapted to the needs of industrial customers, while having a core of reasonable size.
The other essential ingredient at the core is fuel. In the graphite matrix we use Triso fuel, already produced in large quantities and qualified quite widely. These are very small balls of around a millimeter in diameter, made up of three layers which give them great robustness, and assembled in small pellets which are stacked on top of each other to slide them into the graphite matrix. .
The fuel is cooled via the sodium, even if the latter is not directly in contact with the graphite. The sodium then comes, thanks to a sodium-air exchanger, to heat the air up to 700 degrees.
What is the advantage of using air as an open loop cold source?
Domnin Erard: The air loop is open for reasons of simplicity, safety, and because it confers advantages at the industrial level. We take ambient air from the environment, which is heated, and it is this hot air which is used directly as such, or as electricity generation capacity, if the customer needs it. a heat-electricity mix. This hot air can also allow the production of steam.
The product we sell is therefore a mix between hot air, steam at different pressure and temperature conditions, and electricity, according to the demands of industrial customers.
Even if electricity is not the heart of the product, it is important to be able to produce it, to be energy independent and that the heart, from an electrical point of view, does not need a connection to the network . Likewise, air cooling ensures us total autonomy and greater safety – air is available everywhere – compared to water-cooled reactors, which are the norm today, knowing that Access to water for industrial customers is not always easy.
What are the technological challenges inherent in the development of Blue Capsule?
Edouard Hourcade : Most of the components that make up our reactor are technologically mature, however their level of integration is rather low, since this is the first time that a sodium-cooled Triso reactor has been developed.
This is where our biggest challenge lies, particularly linked to our choice to separate the sodium from the fuel and to use natural convection.
Domnin Erard: In safety demonstrations, it is not so much the components that can pose a problem but rather the systems. The latter are very complex, interconnected, and it is not always easy to demonstrate their perfect robustness.
To remedy this, we have chosen to develop the simplest systems possible. For example, the choice of natural convection, if it ensures great robustness in relation to the risks of breakdowns and in terms of failure variability, must be the subject of a demonstration which proves this over all conditions. Operating.
What is your strategy for carrying out this demonstration?
Domnin Erard: We are currently setting up a short-term experimental installation, which should demonstrate our understanding over a relatively wide range of operation of the natural convection of the primary sodium circuit. We need to prove that we are capable of modeling this convection, calculating it realistically and measuring it.
With the aim of showing that the primary circuit, which has neither pump nor adjustment system, naturally behaves correctly and robustly. This includes the fact that if we change an input data, there is an automatic rebalancing specific to natural convection.
Following this experiment, which will extend over almost a year, we will move on to the second stage which consists of developing a non-nuclear prototype, close to the scale of the reactor. It will not be at scale one in terms of power, since we are targeting around 10% (of the power) of the reactor we are selling, which will be 150 MWth. This prototype should allow us to show that we are capable of creating simple systems, sufficiently undependent on each other to avoid complex effects of interactions between them.
The entire nuclear part will be simulated, so that future operators are able to train and the operator can have an almost complete vision of the installation.
Who are the industrial customers for Blue Capsule?
Edouard Hourcade : We are targeting customers requiring powers in the hundreds of MW as well as high temperatures.
This may therefore concern plug-in type markets, where our installation replaces a product already used on site in order to decarbonize the process. For example on sites where soda is produced, which requires very large quantities of steam. Another typical example is methane steam reforming, which is today the most widely used way to produce hydrogen, and which also requires a lot of heat.
This more generally concerns industrial customers who need steam and carbon-free electricity.
We then have more prospective markets, such as energy deserts where cold springs are non-existent, or water desalination activities. These are markets with a 20/30 year horizon.
Comments collected by Pierre Thouverez
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