To save HN a search: a stable isotope used as a neutron capture target, to produce lutetium-177[i], used in targeted radioligand therapies[ii]. Discussed once on HN[iii].
[i] https://isotopes.gov/Ytterbium-176_is_Available_Now
[ii] https://en.wikipedia.org/wiki/Lutetium_(177Lu)_vipivotide_te...
[iii] https://news.ycombinator.com/item?id=40690196 ("Radioactive drugs strike cancer with precision (knowablemagazine.org)")
https://www.globenewswire.com/news-release/2026/08/26/335139...
[0] https://www.discipulusventures.com/ [1] https://www.forbes.com/sites/davidjeans/2025/02/10/silicon-v... (paywall)
Interesting revival of or use of old technology to accomplish their goal. I'm not sure this belongs as a private tech company. I feel like it should be under the control of the federal government and no, I don't care what the libertarians on HN think about it. This needs to be a regulated company and process with clear reporting responsibilities and permanently disruptive penalties for noncompliance by individuals and the corporation.
What has changed here to make them competitive again? Or are they counting on selling small quantities at close to any cost for R&D reactors?
Speaking of which, whatever happened to laser enrichment? That was apparently very promising at some point?
It's not that difficult from an engineering perspective, the tech is almost a century old. It's just that we will drop bombs on anyone who tries.
Nuclear nonproliferation relies on active enforcement.
low-enrichment (~20%) is what's happening here.
the bad stuff, for nukes, is ~90% enrichment.
Anyways, I didn't mean to downplay it.
https://en.wikipedia.org/wiki/Separation_of_isotopes_by_lase...
There are many, many steps before "drop bombs".
I don't recall us bombing Pakistan, India, Israel, China, or North Korea.
> Nuclear nonproliferation relies on active enforcement.
The comedy hour at HN has arrived. See above ^^^
Calutrons are using the same principle of separating ions by their mass/charge ratio, just in a preparative scale (you want to collect what is separated) rather than analytical (you just want to know how much of what).
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.
A mass spec used as an instrument measures the components of a substance, this is just the same concept for actual separation of components not just to look at them
>"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.
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.
https://world-nuclear.org/information-library/nuclear-fuel-c...
Hence there technically being no enrichment cap for any country that signed the NPT and stuff (not to be confused with protection from US bombs or rogue states that never signed the NPT).
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.
Dallas, TX, August 26 — Actinide, an advanced materials company that designs, builds, and operates its own isotope separation machines, has become the first startup in history to produce high-assay low-enriched uranium (HALEU). The enrichment was performed on the company's first-generation calutron, which, weeks earlier, was producing Actinide’s flagship commercial product: enriched ytterbium-176, delivered to Oklo Isotopes.
There is no end-to-end domestic supply chain for HALEU-based fuel: the Department of Energy says that most advanced reactor designs require HALEU, yet there is currently zero available from domestic suppliers. While conventional centrifuge enrichment is able to produce enriched uranium hexafluoride gas, this still must be converted into solid form before fuel fabrication - a process for which the United States has zero commercial capacity. The Department of Energy contracted six companies in 2024 to build out that deconversion capacity, but Actinide’s technology bypasses the bottleneck entirely by producing solid HALEU directly.
The HALEU was produced in research quantities under the laboratory-scale exclusion in NRC regulations, which carves out facilities used for experimental purposes only. U.S. law defines HALEU as uranium containing more than 5 percent but less than 20 percent uranium-235. An independent ISO/IEC 17025-accredited laboratory assayed the produced material at 15.38% enrichment. This material would still need to be fabricated into rods, pellets, or particles before a reactor could use it.
“This demonstration is a testament to the power and flexibility of our technology. 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.
Actinide’s first-generation calutron is a modern electromagnetic isotope separator that sorts atoms by mass inside a magnetic field. It builds on the same core principle used in the Manhattan Project calutrons at Oak Ridge’s Y-12, but the resemblance ends there. Modern magnets, vacuum systems, power electronics, and controls, refined by proprietary trade-secret advances, deliver the highest productivity of any calutron of its size ever constructed.
The United States built calutrons at Oak Ridge during the Manhattan Project and continued using some of them to supply stable isotopes for medicine, industry and research until 1998. The Department of Energy has since rebuilt federal electromagnetic-separation capacity and is expanding it, but the capability remains concentrated inside the government. America’s dependence extends to uranium enrichment: in 2025, 77% of the enrichment services purchased by U.S. civilian reactor owners came from foreign sources, including 26% from Russia, compared with 23% from American sources.
“America should not have to ask another country for the materials that determine whether a reactor runs or a cancer treatment gets made,” said Eric Olszewski, co-founder and CEO of Actinide.
The company is building Fortitude, its second-generation separator. 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.
Actinide was founded in September 2025 after seven years of research and prototyping by Mendelsohn. Olszewski began financing the work before the company was incorporated, moved his family to Dallas in early 2024 to join Mendelsohn in the lab and invested more than $1 million of his own capital. Actinide raised an oversubscribed seed round in March 2026 led by Onto Ventures, with participation from Neo Ventures, Mana Ventures, Discipulus Ventures, Shor Capital, angel investors Ryan Hiepler, Stephen Cole, and others.
“Whether the application is nuclear energy, cancer medicine or quantum computing, the choke point is the same: access to the right isotope. And almost everyone attacking it is years from producing anything. Eric, Robert and the Actinide team designed and built their own separator, shipped material to a paying customer, and then made HALEU. They’re rebuilding America's isotope capacity and we’re proud to be on that journey with them." - Tom McQuillen, Onto Ventures
About Actinide
Actinide builds modern calutrons — electromagnetic isotope-separation machines — to produce atomically precise materials at scale. Using its first-generation calutron, Actinide has produced and sold ytterbium containing more than 95% ytterbium-176 and has enriched natural uranium into the HALEU range at research scale. Actinide is now building Fortitude, its second-generation system, to expand domestic production of materials required for medicine, nuclear energy, and advanced technologies. Founded in Dallas in September 2025, the company is on a mission to reshape the future of humanity, atom by atom.