[holowoodman]

I guess mass produced nukes would rather be enriched uranium based, due to the far easier construction. No fiddly implosive lens assembly. No weird multi-phase cristallization that goes critical if you blink. Metal that is merely as dangerous and nasty as lead, magnesium or arsenic, not plutonium.

If you really want to go carpet-bombing with nukes, miniturization isn't as important as having a lot, quickly and reliably.

[sadhorse]

Enriching uranium is more expensive than making plutonium by a long shot. Modern nukes are two point implosion, not really fiddly. And when was the last criticality incident related to phase transition? Can't remember one.

[credit_guy]

> Enriching uranium is more expensive than making plutonium by a long shot

I'm not sure. This used to be the case in WW2, but today enriching uranium is quite inexpensive.

Here's an enrichment calculator [1]. The cost of enriching to 80% (weapons grade uranium) is $80000/kg, so you can enough uranium for a Hiroshima-style bomb for about $5 million.

$5 million for a nuclear bomb is basically nothing.

[1] https://www.uxc.com/p/tools/FuelCalculator.aspx

[ben_w]

That's worryingly cheap, but it also feels unlikely due to all the fuss made over stopping Iranian centrifuges.

I assume that's something like the amortised cost over the lifetime of a factory dedicated to making them, rather than something which at least a few people on this forum can personally afford?

[credit_guy]

The webpage that calculator is on is maintained by a nuclear industry market research company, UxC. UxC does not itself run enrichment facilities, but Urenco does, and here's a calculator provided by them [1]. The output of the calculator is separation work units (SWU), the standard unit used in the industry. The two calculators produce exactly the same result.

Urenco is a company that specializes in uranium enrichment. It is owned by the UK government (1/3), the Dutch government (1/3) and 2 German energy companies. They will not sell you weapons grade uranium, and if you don't have a legitimate reason, they will not sell you anything.

But if the UK or the US government asks them for weapons grade uranium for the purpose of making nuclear bombs, I imagine that they would be willing to provide.

As for Iran, they needed to build from scratch the many thousands of centrifuges, and they don't have any paying customer that could help recoup some of the cost. Plus, for a long time they needed to do the enrichment in a covert way, to hide it from the International Atomic Energy Agency inspectors. Once they were caught enriching, they first got hit by Stuxnet then they got sanctioned. Then they did a deal with the US and some European countries, where they promised to stop the enrichment, which they did. They restarted when Trump withdrew from the deal, and now they have enough enriched uranium to make several bombs if they want.

[1] https://www.urenco.com/swu-calculator

[giantg2]

It's probably a lot easier if you're recycling the semi degraded stuff out of the outdated warheads that need to be dismantled anyways.

[harshreality]

Does the U.S. make weapons-grade U235 anymore except for research? I thought gun-type fission weapons were phased out for safety and efficiency reasons. I also thought essentially all "fission" weapons today are fusion-boosted, and I thought the implosion type was the only production-ready design of fusion-boosted weapons.

[GemesAS]

The US isn't producing HEU anymore but still has a decent sized stockpile of it.

A number of the pits in the active stockpile are actually composite Pu/HEU pits & you can actually use HEU in implosion weapons as well.