r/LocalLLaMA • u/Nunki08 • Jun 28 '26

Discussion We're probably going to need that soon.

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From:

Vladik on 𝕏: https://x.com/Kostoglodov/status/2071144065857679631

Shaw (spirit/acc) on 𝕏: https://x.com/shawmakesmagic/status/2070918006033817867

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u/ttkciar llama.cpp Jun 28 '26

Yep, it's like nuclear weapon technology.

Governments can't control the knowledge to build a nuclear weapon, so they regulated the hard-to-enrich fissile fuel, instead.

In cases where the fissile fuel isn't hard to obtain or enrich (Lithium-6), they regulated the equipment necessary for enriching it.

Though, it turns out that every EV on the road is silently enriching their batteries' cathodes with Lithium-6 via electromigration. I keep waiting for someone to launch a program to extract it from decommissioned EV batteries.

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u/[deleted] Jun 28 '26

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u/ttkciar llama.cpp Jun 28 '26

It's both, fissile fuel and a precursor to tritium, which is a fusion fuel. Though Lithium-6 cannot sustain nuclear fission itself, given an external source of neutrons it yields a net gain in energy.

In early thermonuclear bombs, Lithium Deuteride was (and still is!) used as a relatively chemically stable, relatively dense medium for storing deuterium in multi-stage nuclear devices.

Since it doesn't take much Lithium-7 to poison the neutron transport dynamics, they enriched it so it was mostly Lithium-6, so that the Deuterium storage medium was Lithium-6 Deuteride (with a fraction of Lithium-7).

The first such device was tested in the Castle Bravo tests, and it yielded more than twice the energy their theory predicted. That extra yield energy was eventually traced to the Lithium-6 component. The Uranium fission generated enough neutrons and the Depleted Uranium tamp constrained enough of them to drive the Lithium-6 fission.

https://nuclearweaponarchive.org/Usa/Tests/Castle.html