"Ed Huntress" wrote in message
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"CaveLamb" wrote in message
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Ed Huntress wrote:
Forget the heat. A 5" sphere of Pu 239 is roughly a critical mass. g

Of course, the waste product from a breeder reactor contains several
isotopes of plutonium, which have various effects that are beyond my
understanding, but I wouldn't want to be on the same planet with a 25'
cube of it.




A 25 foot cube would be the breath of hell...

When you mix in Pu 240, which, I'm told, is a substantial portion of the
Pu produced in a powerplant breeder reactor, the critical mass becomes
*much* larger. But, jeez, this is not something from which to draw
conclusions about waste disposal unless you have a good handle on
plutonium and nuclear fission.

The fast breeders produce more Pu 239, according to some sources I've
read. But all of the science in those layman's descriptions is so
dumbed-down for us layers that I don't really know what the story is. We
do dispose of weapons-grade Pu 239 by somehow oxidizing it and melting it
with borosilicate glass. Again, this is not something to try at home. d8-)

But a sphere of high-grade Pu 239 metal larger than 4" or 5" is
impossible. It would be Trinity, all over again, before you made the ball
any bigger than that.

(Well, not quite, because the plutonium you would try to add to a
subcritical mass explodes before the mass of material can become
supercritical -- and it's not a result of fission, exactly. That's why
gun-type triggers ((which we used in the Little Man bomb on Nagasaki))
don't work with plutonium cores. You need U 235 for that.)

Correction, that was Little Boy, and it was the (previously untested) bomb
we dropped on Hiroshima.

--
Ed Huntress