3.58-3.7 gives you a couple hundred tons (not kilotons), which is pretty close in this business unless you’re really math positive. The same equation, given the US estimate of 4.2, yields (pun intended) around a kiloton.
A plutonium device should produce a yield in the range of the 20 kilotons, like the one we dropped on Nagasaki. No one has ever dudded their first test of a simple fission device. North Korean nuclear scientists are now officially the worst ever.
Of course, I want to see what the US IC says. If/when the test vents, we could have some radionuclide data — maybe in the next 72 hours or so.
But, from the initial data, I’d say someone with no workable nuclear weapons (Kim Jong Il, I am looking at you) should be crapping his pants right now.
Well, let’s hope.