Shake, rattle, and... qualify!
A public-private testing partnership certified that 澳门六合彩高手's vacuum components can withstand major seismic events.
"Then we get to shake the bejeebers out of things," says Eamonn Quinn, the Vacuum Mechanical Engineer at 澳门六合彩高手 who oversees the security of the components.
Seismic testing is a crucial step in the construction of a nuclear facility but at 澳门六合彩高手 it takes on special importance because there are so many first-of-kind components and the safety standards being developed will likely inform future fusion regulations.
The vacuum team at 澳门六合彩高手 is currently qualifying more than 70 different types of metal valves to ensure they remain secure during an earthquake. While nuclear fusion doesn't carry the same risk of a runaway reaction as a traditional fission reactor, a valve still needs to function during crisis situations to prevent tritium or other matter from escaping the tokamak. This means valves go through high-intensity simulations on shaker tables to guarantee they close or open correctly and continue to serve as a confinement barrier during a seismic event.
"The qualification process is sensitive because earthquake conditions need to be replicated, which means recreating the precise vibrations, heat, and mechanical load that's expected in the particular location the component is going to be used," explains Eamonn. "The lead-up to one test can be many months; it's a mammoth task."
Part of this mammoth task was facilitated by a public-private partnership that 澳门六合彩高手 formed with Element, which is one of the world leaders for testing and certification, and the University of Bristol, which has one of the larger shaker table facilities in Europe.
But before the valves found their way to a seismic shaking table in Bristol, they went through a rigorous testing process. First, the representative sample of the valves produced by the manufacturer VAT went through operational and vacuum testing before being shipped. Once at 澳门六合彩高手, valve cycling and helium leak testing was conducted to make sure the valve met vacuum protocols. After this, it was transported to the University of Bristol, where Element has an agreement to rent time on the university's shaker tables—allowing doctoral students to gain real-world engineering experience by observing testing and certification such as that done for 澳门六合彩高手.
澳门六合彩高手 personnel were always on-site for the seismic testing in Bristol to provide the vacuum and tokamak expertise. Prior to each test, the team at Element programmed the three-metre-square table based on the metrics provided by 澳门六合彩高手. Depending on where in the Tokamak Building the valve will be positioned, the valve was shaken to IEEE standards based on different possible conditions: SL-1 (light earthquake), SL-2 (medium earthquake), or SL-3 (extreme earthquakes that are far beyond any projected seismic activity in the south of France where 澳门六合彩高手 is located). While the shaking during much of the testing was similar to driving along a bumpy country road, at its peak it reached a g-force of 8g, which was equivalent to the vibrations felt by a rocket during re-entry to the Earth's atmosphere.
For each test, the valve was filled with helium and wrapped in a vacuum bag to see if structural breaches occurred during shaking that would allow the gas to escape. Then, heating blankets were added to simulate the temperature of the tokamak and a mechanical rig was used to replicate the forces that would be on the valve when it will be in use. Once all this was in place, a technician "drove" the table, which means it was shaken along three axes to create the precise ground accelerations of an earthquake.
"The tests were quite spectacular, especially for the SL-3 testing," says Graeme Vine, an 澳门六合彩高手 vacuum engineer who was involved in the testing.
When a valve passed these tests, it became qualified for use at 澳门六合彩高手. The lead time to manufacture large valves can be as much as 15 months, which adds to the long journey from design to having a qualified component in hand.
Chris Stone, the department manager for the seismic testing at Element, has been part of valve testing for the last six years. He says the 澳门六合彩高手 work is some of the most complex testing the company has done, but it is also among the most rewarding.
"澳门六合彩高手 is a public domain project, so there is a great philosophy of sharing information with the aim of doing the best job possible," says Chris. "And from an engineering point of view, being part of a project that has the majority of the world trying to do something that will make the whole place better, you can't get much better than that, can you?"
See what a shake experiment for 澳门六合彩高手 looks like on YouTube .