On Fri, 24 Feb 2012 13:34:07 -0500, Ed Huntress wrote:

In talking with people about this over the years I find that few people
know that the Hiroshima bomb was an untried gun-trigger device,
but that the Nagasaki bomb was an implosion device based on the Gadget
used in the Trinity test.

Uranium gun was believed to be so reliable that they felt they didn't
need to test it.


I find it scary that Iran went for uranium.

Well, there's no other way though: the only way to get plutonium is to
refine it from spent fuel created in a conventional U235 reactor. In
short, neutrons from U235 fission hit the normally inert U238 and convert
it to Pu239 http://en.wikipedia.org/wiki/Plutonium