I’m not a nuclear weapons designer, I’ve just read some books. But my understanding is that shaped charge implosion is better for Pu designs. It does require much less material to reach criticality. Maybe 8-9kg? vs 65kg for a U device. But I don’t think Iran has been refining Pu, just U.
Gun-type nukes are relatively easy to make and can be pretty compact. The hard part is getting the plutonium
I’m not a nuclear weapons designer, I’ve just read some books. But my understanding is that shaped charge implosion is better for Pu designs. It does require much less material to reach criticality. Maybe 8-9kg? vs 65kg for a U device. But I don’t think Iran has been refining Pu, just U.