You would need IR-6 or IR-4 at the minimum. Let’s say both have an SWU of 5. That means with one single cascade (170-200 centrifuges) they could do the work of 1,000 IR-1’s.
Now the only hurdle to your theory is that every centrifuge workshop (only a few exist) are observed by IAEA and all of the West intelligence services. While it’s not out of realm of possibility iran has hidden 1 or 2 centrifuge production workshops, there is no evidence of that. These sites would also need to be completely sealed off and known to just a handful of leaders inside Iran to prevent detection from moles and spies within Iran’s power structure from leaking to West.
Again not impossible, but not an easy feat either given the massive intelligence leaks Iran has had happened in the last 20 years.
Why would there be "evidence" for secret sites? The journalist who propagated this theory was saying that there is a possibility that a handful of known facilities could be a bait and diversion. Only a FOOL would rely upon IADS or a few layers of concrete to stop a mad US/NATO+Israeli attack on Natanz, Bushehr, Fordow etc.
If the words of people from IAEA, Israel, US are gospel then Iran in 2003 already had neutron guns ready for installation on fission core, Parchin was a secret facility so there is considerable evidence that Iran is not playing a sincere game either. There is secrecy in motives from Iranian side because no country on earth otherwise produces 60% U235 in masses.
As for the feasibility of such micro-sites as the guy tweeted. Here is a very possible scenario (pure mathematics):
Trump takes office and settles Iran will have something like 285 KG of 60% enriched U235. IAEA reported the last quantity of 183 KG in November with a 34 KG/month addition rate. By February (3 months) it will be 285 KG.
Hypothetically if there are 40 such micro sites spread across Iran, some in mountains, some in plain sight in urban centers (Shabani's theory) etc then there will barely be small buildings or underground compounds of 100 m^2 area having 3-4 x cascades of IR-4 (5 SWU/year) that can bring 8 KG of 60% U235 to WGU (>90%) within a week to yield a 5 KT device worth 90% WGU. 285 KG means roughly 40 such devices can be made in February. If they start using the extremely efficient C-fiber IR-8 (20-24 SWU/year) then this conversion will take 2-4 days with a single cascade. There are IR-8 at Natanaz.
That was pure mathematics. Considering politics and everything else can it actually happen? Like I said no one knows.
2-6 KT device can annihilate entire Industrial towns, ports, Large military bases, the largest of aircraft carriers, etc. With a powerful missile force like that of Iran, 40 such devices are enough deterrent to push enemies back but mullahs are pu$$ies so they would rather talk with US and keep on cursing Israel in the press.
