Discover vacuum engineering
Primary vacuum, secondary vacuum, sealing, so much specialized expertise for Axima Nucléaire: Interview with David Primas
When we think of vacuum, we of course think of space. But did you know that vacuum is used in many industrial applications? And that there are several types of vacuum? David Primas, Business Manager at Axima Nucléaire (an Equans entity) explains.
To begin with, could you give us your own definition of emptiness?
A definition I like of the void: "it's what's left when you've removed everything you knew". For example, if you remove all the particles, the atoms in a cubic centimetre of air, you'll find about 10 billion billion molecules under normal conditions. But in a primary or secondary scientific vacuum, we reduce the number of particles even further. You end up with fewer molecules, to the point where they no longer touch, and switch from viscous to molecular flow.
So total emptiness doesn't really exist?
In reality, a vacuum is never completely empty. To create a vacuum environment, we use a vacuum system that pumps out a very large number of particles, so that those that remain are so far apart that they can't manage to touch each other. This creates a tightly sealed environment, safe from molecular disturbances.
But then, what are the major industrial needs that require the creation of vacuum?
Vacuum levels vary: coarse vacuum, for example, is used in ventilation or food preservation. If we go further, we reach primary vacuum, then, even further, secondary vacuum. We enter more technical applications: such as protecting a system, manufacturing or experimentation.
If you're using high-power lasers and don't want them to be disturbed by any molecules or particles they may encounter, a primary or secondary vacuum is necessary.
Even when manufacturing microchips for a computer or telephone, vacuum is also needed to protect the elements. Vacuum can also be used for more experimental applications, such as in space or fundamental research.
The industrial applications of vacuum are therefore numerous: it is used in fields requiring tightness, to avoid contamination by external agents, notably in the healthcare and space sectors. Beyond vacuum, tightness is a long-standing expertise of Equans. The group operates, for example, in the nuclear sector to detect leaks in machine assemblies, glove boxes or flanges, and offers tailor-made solutions to suit the needs of installations.
What are the advantages for your customers of working with Equans on projects involving vacuum and sealing systems?
Our customers find it worthwhile working with us, because we offer a complete package: we are able to carry out the studies, manufacture the piping networks, and carry out all the necessary tests. We take care of the entire manufacturing process, from A to Z, with all the associated controls. We also take care of the assembly of these elements, and carry out performance and safety tests, such as overpressure and leak tests, or methods like dye penetrant testing of welds.
David, you are one of the few people in France to be certified as a level 3 expert to COFREND (COnfédération FRançaise pour les Essais Non Destructifs) standards. Can you tell us more?
COFREND stands for non-destructive testing, which represents a whole range of tests carried out on manufactured equipment to determine, without destroying it, whether it conforms to specifications and the desired standards. There are many different methods: dye penetrant testing, radiography, visual inspection, and many others, including leak testing. I've been working in this field for 25 years, and for almost 10 years I've been COFREND 3 in watertightness, which enables me to design and find the best solutions.
You've been involved in some emblematic projects. Can you name a few?
There are extraordinary aspects to the vacuum. I had the pleasure of working on the Ariane rocket engine test bench. We had to create a vacuum around the engine to reproduce the conditions encountered in flight. What was fascinating was that, once the engine was ignited, it was the flame that self-maintained the vacuum around the engine.
Can you tell us about your work on the Laser Megajoule, and the challenges it poses in terms of vacuum and sealing?
The Laser Megajoule is a military project designed to work on nuclear fusion. The system relies on laser beams that are amplified to fuse a small target, creating a "mini-sun". This mini-sun is contained in a huge sphere evacuated during fusion, with numerous instruments all around to verify the data.
I have to say that working on over a kilometer of piping, and designing this system from A to Z with all the sealing issues, was an exciting experience.
And today, you're working on the ITER (International Thermonuclear Experimental Reactor) project?
This is a major project to develop fusion nuclear power plant technology to produce more energy and achieve even higher levels of safety than conventional fission power plants. It's a fascinating project, and I'd say it's something of a Holy Grail in this field. I really have a lot of good memories in this field, it's a passion.
