alt Hacker NewsI remember hearing somewhere on this site that medical imaging got pretty good at building systems that recycle helium. Does chip manufacturing not do this or are the losses at their scale are still large enough that you need a substantial constant supply?
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observationist • today at 6:42 PM
Some of the fabs do recycle as effectively as they can, but MRIs use it in a single process, in liquid form, in a relatively constrained container. Fabs use it for a variety of processes, ranging from wafer cooling to purging environments, to making ultra ultra clean chambers. The scale of what they use is higher, too, so even if an individual process is more efficiently recapturing helium, they might go through a few tons a day, with an MRI only using a few liters and losing 5% or less.
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The big problem is purity. Fabs use grade 5 and 6 helium where contaminants are 1-10 parts per billion. The infrastructure to get it that pure becomes very specialized and any time the helium goes through a process it picks up so much contamination that recycling it would require the entire purifying and quality control infrastructure for pressure or temperature swing adsorption.
Some fabs are starting to reuse helium in downstream processes but there’s only so much they can do without expanding their core competency into yet another complex chemical manufacturing process.
MRI machines don’t need high purity helium and the contamination doesn’t “gunk up” all the tools so it’s not an issue to recycle it there.