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> What has changed here to make them competitive again?

The article has to be read carefully. "On Actinide's engineering estimates, a single Fortitude machine would provide roughly half the isotope-separation capacity of the U.S. government's current electromagnetic fleet."

The "U.S. government's current electromagnetic fleet" is tiny. Oak Ridge is building a modest plant.[1] Idaho has a benchtop-sized separator. That's what Actinide is comparing against. Not the rows of basketball court sized calutrons from WWII. So the announcement gives the impression of a larger operation than it really is.

> Speaking of which, whatever happened to laser enrichment? That was apparently very promising at some point?

That is a very good question. A company called Silex, and their subsidiary Global Laser Enrichment, has been trying to commercialize this for years.[3][4] Exactly how they do this is classified.[5]

There's another startup in this area, crawling along, underfunded, but building something.[6]

Meanwhile, URENCO continues to operate a centrifuge plant in New Mexico.[7] URENCO is a a European company, and seems to be the leader in centifuge technology. Units in France, Germany, the Netherlands, and the US.

I've been expecting something big to happen in the laser enrichment area since the 1990s, but it never has. This suggest that it either doesn't work very well or is being suppressed because it works too well.

[1] https://www.energy.gov/science/articles/doe-expands-stable-i...

[2] https://inldigitallibrary.inl.gov/content/uploads/50/2026/04...

[3] https://www.silex.com.au/

[4] https://www.gle-us.com/

[5] https://www.nrc.gov/docs/ML2304/ML23045A117.pdf

[6] https://laseristech.com/

[7] https://urencousa.com/

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A friend of mine was involved with AVLIS and Pu-AVLIS. There were/are significant counterproliferation concerns with them. I'm not sure if that has anything to do with the lack of major commercialization, but I wouldn't find it shocking if it were true. As I understand it, it's one of those technologies that the US doesn't strictly need, but we really don't want the Iranians (or similar weapons-pursuing state) to have it.
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They talk about that in the article:

>"A centrifuge plant does one thing, costs billions, and takes years to stand up. Our machines cost a few hundred thousand dollars, produce material within months, deploy anywhere, and are able to be reconfigured in a matter of days to separate various isotopes as they are needed," said Robert Mendelsohn, co-founder and CTO of Actinide.

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The obvious thing to consider is throughput and yield/loss. A centrifuge plant can produce kilograms of material and doesn’t fundamentally misplace any material, although it may struggle to extract all the inputs that are the correct isotope. A calutron needs to ionize every single atom, accelerate it to an appropriate energy, deflect it, and decelerate it without losing it. And it needs to deal with inadvertently multiply-charged ions. And if you’re dealing with radioactive source material, you need to deal with the atoms that embed themselves in your apparatus.

At least uranium isn’t actually all that radioactive.

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This is a bit uncharitable to the concept of a centrifuge here. The Iranian nuclear program seems to have centrifuges that are a lot smaller and cheaper, and you can certainly build one that meets these needs.
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yeah they don't talk about cleaning them either... that's a massive problem in this kind of ion separation techniques, things splatter and stick everywhere.
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> What has changed here to make them competitive again?

Nothing. This is a company that specializes in making medical isotopes, which is something Calutrons are good for - you need high levels of enrichment in a single step, you don't need to process large quantities, and the energy consumption doesn't matter. Any talk of using it for reactor fuel production is pure PR spin.

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Take these numbers with a grain of salt because I got them by chatting with AIs, but if you're producing electricity from HALEU, then centrifuges require reinvesting <1% of the output, whereas historical calutrons required 200% (useless) and modern technology could potentially bring that down to 10%.

So calutrons will always be less energy efficient than centrifuges, but if the capital cost and construction time is low enough, calutrons might still be economically viable.

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If we wanted to find out what an LLM thought we'd ask the LLM. Don't be a meat proxy.

https://gruhn.me/blog/2026-08-03/

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But you weren't going to ask the LLM, and now you know something you weren't aware of. Seems no different than someone reporting what they found out in a Google Search, as long as they disclose that they used an LLM (as long as they used one that actually searches the web, but pretty sure even ChatGPT Free does that these days).
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One of the more annoying pre-llm behaviours was responding with the first link of google when a question was asked (but not of them specifically).
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> but pretty sure even ChatGPT Free does that these days).

It can do, but won't do so reliably; and the guessing it does if it's not grounding with a search is still like someone in a pub saying "I recon…". Admittedly, a Cambridge pub like the Carlton Arms used to be when I lived there (sometimes I'd be the only one at the table who wasn't studying for a PhD), but still, pub.

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Even if you ignore my LLM numbers, "what percent of a reactor's output must be reinvested to enrich its own fuel?" is a meaningful contribution to the discussion.
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This site is intended to be a discussion between people. If we wanted to consult some other resource, we would go do that. Injecting unverified information is not a contribution to a discussion between people, especially if it isn't coming from a human source.
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But are your numbers reliable? By your own admission you don't know. So you aren't contributing expertise but rather the brief use of a tool that everyone has ready access to and which doesn't necessarily return reliable answers. AKA noise, at least from the perspective of a community like HN.
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Are you a meat proxy for that blog post?
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>Under the Atomic Energy Act, all information not specifically declassified is classified as Restricted Data, whether it is privately or publicly held

https://en.wikipedia.org/wiki/Separation_of_isotopes_by_lase...

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Well, for one thing, the only existing Yb-176 production facilities are in Russia. That means demand for a domestic supply is pretty high right now.

The other thing is that for a nuclear reactor, you need many kilograms of uranium. But for a Pluvicto patient, you need less than a gram of ytterbium.

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