[twothreeone]

Wikipedia points to a source that says it is used for parts of a multi-stage fusion bomb:

> Uranium with enrichments ranging from 40% to 80% U-235 has been used in large amounts in U.S. thermonuclear weapons as a yield-boosting jacketing material for the secondary fusion stage

Source: http://nuclearweaponarchive.org/Nwfaq/Nfaq6.html#nfaq6.2

[sorcerer-mar]

Ah yes, alongside the weapons grade steel and weapons grade copper.

[Retric]

There’s no minimum qualification for steel to be useful in a bomb, there is for uranium which this meets.

[mindslight]

Just to be clear, this isn't "useful [to make] a bomb" - it's useful in a thermonuclear warhead that already has a primary fission stage using the originally-mentioned highly enriched weapons grade uranium, plus a second fusion stage that (as far as I'm aware) Iran is not working to develop.

edit: phrasing. it feels like we're going around in circles nitpicking based on a poor framing and the tendency for innuendo on this topic

[Retric]

You might want to rephrase that as a thermonuclear warhead is obviously a bomb making it “useful in a bomb.”

Also, you can use 60% enriched uranium in the primary stage at the cost of a much larger, less efficient, and dirty device.

[05]

> plus a second fusion stage that (as far as I'm aware) Iran is not working to develop.

All modern nukes are two stage designs, Iran would be insane not to have a fusion stage. It would basically be a Hiroshima style dirty bomb with just 1.5% fissible mass actually fissioned.

[mindslight]

I'm well aware of the difference in yield, but I thought a second fusion stage required modeling and testing well beyond basic development? Like I take a quick look at Wikipedia for what devices (for example) India has, and it seems to say whether they contain a significant fusion stage is an open question.

Hiroshima was pretty terrible as it was. And I thought the capability that everyone focuses on because it gets nations a seat at the nuclear table was just basic fission weapons. But please correct me if I am wrong.

[05]

> I thought a second fusion stage required modeling and testing well beyond basic development

The bottleneck is UF₆ centrifuges, not the modeling. They're definitely aiming for a fission-fusion design: "The sources note that Iran has attempted to produce deuterium-tritium gas on its own inside Iran - with the help of Russian scientists - but has so far been unable to do so, and due to pressures by the Iranian leadership to accelerate the weapons production program, decided to try to purchase this substance abroad." [0]

India and Pakistan did their first tests ~30 years ago, a lot has changed since then and if you're building a nuke in '25 might as well spend some cash on a simulation cluster and buy some multiphysics simulation software from Russia..

[0] The sources note that Iran has attempted to produce deuterium-tritium gas on its own inside Iran - with the help of Russian scientists - but has so far been unable to do so, and due to pressures by the Iranian leadership to accelerate the weapons production program, decided to try to purchase this substance abroad.