On Feb 12, 7:29 am, " wrote:

Uranium? I might buy plutonium, but 2 kg seems way low for uranium,
even with a ferocious amount of compression. And the pit, at least in
the drawing, looks solid rather than hollow, which would lessen the
amount of compression.

I gathered that they devoted more effort to the design of the
detonation chamber than to the bombs... or at the very least, more of
their chamber-effort was publicly releasable than their bomb-effort.