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Stubsack: weekly thread for sneers not worth an entire post, week ending 2nd November 2025


https://awful.systems/post/6006438?scrollToComments=true

in reply to Soyweiser

That post requires signing in to view; it's a link to this: futurism.com/science-energy/tr…
in reply to blakestacey

Trump Administration Providing Weapons Grade Plutonium to Sam Altman


The "Weapons Grade" part is almost certainly editorializing (hopefully), but this whole shit sounds like another Chernobyl waiting to happen

in reply to BlueMonday1984

The "weapons grade" almost certainly means 239-Pu, which is used in bombs or fissile in reactors. (There are other isotopes but they're not really useful for fueling reactors *or* making bombs.)

I'm rather partial to the idea of silly valley oligarchs putting crude A-bombs under the table at one another's shareholder meetings.

in reply to Charlie Stross

every batch of plutonium is made mostly out of Pu-239 that's just how plutonium works. it can't be separated into isotopes in any meaningful amounts so any batch of plutonium is also a mix of a couple of isotopes. reactor grade might be something like 55% Pu-239 plus say 12% also fissile Pu-241 with the rest being nonfissile Pu-240, Pu-242 and Pu-238 in that order. the newer reactor and fuel pin design, the higher burnup and the less fissile isotopes will be present at the end of the cycle. even in purely uranium fueled reactor about third of energy at the end of the fuel cycle comes from plutonium bred in the same fuel pin. i can elaborate on that if you want to
This entry was edited (2 weeks ago)
in reply to fullsquare

AIUI for optimal nuclear weapons (ie. lightweight pits that maximize fission) you need to be very careful about which phase of metallic plutonium you use (it has dozens). IIRC an alloy with about 2% germanium in delta-phase is densest: make it with as close to 100% Pu-239 as you can get. (This was declassified in the 1970s.) You're also going to need some tritium gas to fill the hollow core, and other exotica (never mind the carefully timed explosive lenses to drive the implosion).