Discover Vacuum Engineering
Primary vacuum, secondary vacuum, leak testing—all areas of specialized expertise for Axima Nucléaire: An Interview with David Primas
When we think of a vacuum, we naturally think of space. But did you know that a vacuum is used in many industrial applications? And that there are several types of vacuum? David Primas, Account Manager at Axima Nucléaire (a division of Equans), explains.
To start with, could you give us your own definition of the void?
A definition of a vacuum that I like: “It’s what remains when you’ve removed everything you knew.” For example, if we remove all the particles—the atoms—from one cubic centimeter of air, we find about 10 billion billion molecules under normal conditions. But in a primary or secondary scientific vacuum, the number of particles is reduced even further. We end up with so few molecules that they no longer touch one another, and the flow transitions from viscous to molecular.
So total emptiness doesn't really exist?
In reality, a vacuum is never completely empty. To create a vacuum environment, a vacuum system is used that pumps out a very large number of particles, so that the remaining particles are so far apart from one another that they cannot come into contact. This creates a tightly sealed environment, protected from molecular disturbances.
So, what are the major industrial needs that require the creation of a vacuum?
Vacuum levels vary: a coarse vacuum, for example, is used in ventilation or food preservation. If we go further, we reach the primary vacuum, and then, even further, the secondary vacuum. This leads to more technical applications: such as protecting a system, a manufacturing process, or an experiment.
If high-power lasers are used and we do not want these lasers to be disrupted by molecules or particles they might encounter, a primary or secondary vacuum is necessary.
Even when manufacturing microchips for a computer or a phone, a vacuum is needed to protect the components. A vacuum can also be used for more experimental applications, such as in space or basic research.
There are therefore numerous industrial applications for vacuums: it is used in fields requiring airtight seals to prevent contamination by external agents, particularly in the healthcare and aerospace sectors. Beyond vacuum technology, airtight sealing is a long-standing area of expertise for Equans. For example, the group works in the nuclear sector to detect leaks in machine assemblies, glove boxes, or flanges, and offers customized solutions tailored to the needs of each facility.
What are the benefits for your customers of working with Equans on projects involving vacuum and sealing systems?
Our customers find it beneficial to work with us because we offer a comprehensive package: we are able to conduct design studies, manufacture piping systems, and perform all necessary tests. These components are manufactured entirely in-house, from start to finish, with all associated quality controls. We also handle the installation of these components and perform performance and safety tests, such as pressure and leak tests, as well as methods like penetrant testing of welds.
David, you are one of the few people in France to be certified as a Level 3 expert according to COFREND (French Confederation for Non-Destructive Testing) standards. Can you tell us more about that?
COFREND specializes in nondestructive testing, which involves a wide range of tests performed on manufactured equipment to determine—without causing damage—whether it complies with the specifications and desired standards. There are many different methods used: penetrant testing, radiography, visual inspection, and many others, including leak testing. I’ve been working in this field for 25 years, and for nearly 10 years, I’ve held COFREND Level 3 certification in leak testing, which allows me to design and identify the best solutions.
You've been involved in some landmark projects—can you name a few?
There are some extraordinary aspects to a vacuum. I had the pleasure of working on the Ariane rocket engine test stand. We had to create a vacuum around the engine to replicate the conditions encountered in flight. What’s fascinating is that, once the engine was ignited, it was the flame itself that maintained the vacuum around the engine.
Can you tell us about your work on the Megajoule Laser and the challenges it presents in terms of vacuum and sealing?
The Megajoule Laser is a military project aimed at advancing research into nuclear fusion. The system relies on laser beams that are amplified to fuse a small target, thereby creating a “mini-sun.” This mini-sun is contained within a massive vacuum-sealed sphere during the fusion process, with numerous instruments surrounding it to monitor the data.
I must say that working on over a kilometer of piping and designing this system from scratch—including all the challenges related to leak prevention—was a fascinating experience.
And today, are you working on the ITER project (an acronym for “International Thermonuclear Experimental Reactor”)?
This is a major project aimed at developing fusion nuclear power plant technology to produce more energy and achieve even higher safety standards than those of conventional fission power plants. It’s a fascinating project, and I’d say it’s sort of the Holy Grail in this field. I have so many fond memories related to this field—it’s a passion of mine.
Vous semblez être un transmetteur passionné. Est-ce important pour vous de partager votre savoir ?
Expliquer est difficile, il faut utiliser des formulations simples pour des concepts de physique, et parfois avoir des représentations graphiques originales de certains phénomènes. Sur mon temps libre, je dessine et peins un carnet de voyage, y intégrant souvent des textes, des images issues de mes rêves, de mes phobies et pensées.
