I’m not sure about the difference between Russian and US measurements, but it could be as simple as atom % vs weight %. The two are slightly different.

I’m not sure if your joke was intended or not Yale, but thanks anyway – claiming that their production is halal just wouldn’t have the same ring to it! :-)

Up to a few days ago if the inspectors had found any uranium enriched to around 20% then suspicions would have been raised that secret, “bomb related” work was going on. Now if anything is found, the Iranians just say, “Yeah, well we told you – so what’s the secret?” After all, lab tests are exquisitely sensitive at telling us about what the level of enrichment is, but not half so good as saying when it was enriched, or where.

It seems very suspicious to me that the first batch of ca. 20% enrichment was produced so quickly – almost as if the Iranians were concerned that a 20% enriched particle would be found somewhere in the near future, and they wouldn’t be able to explain it. Now, though, it’s perfectly explicable.

Of course, political shenanigans may be the primary driver of what’s happening, but the time between announcing the 20% enrichment target and (seemingly) achieving it does seem mighty short.

Assuming 24/7 operation and not counting setup time. I suspect that once the Iranians get a cascade set up properly, they probably can run it close to 24/7 for at least a few weeks straight.

This way they get the best of all worlds.

Although the may produce >20% hex due to imprecision in enrichment they will downblend as Carey pointed out and the IAEA will eagerly give them a pass on the overlimit trace samples.

I personally don’t get freaked by Iran enriching to almost 20% – except for their desire to be provocative.

I already passed freaked when they produced 3.5% LEU.

Seventy percent of the heavy lifting in enriching nat-U to LEU is already in the can. It is only a bit longer going from 3.5 to 90% rather than from 20% to 90%. The difference is in weeks not years.

Less than that, even. Calutrons have a very high separative ratio per pass, and get you small quantities of pure material immediately. Centrifuge cascades (and gaseous diffusion cascades, etc) have to establish the enrichment gradient across the cascade before any useful output happens. That’s part of the system start up period. Before the gradient is established nothing is coming out at the eventual target enrichment, though you may be taking a dump quantity off the top to establish the flow volume which the gradient will eventually support. You can re-feed that dump back into the input, as the enrichment slowly ramps up off the top end…