D_Hall wrote:Jumbo was designed to contain the explosion in the event of a fizzle. Plutonium was valuable enough that they didn't want to lose it in the event the bomb didn't go correctly. If it did, the container would go away. If it didn't, the bomb would be contained.
So... you're correct: Jumbo would not contain a proper Trinity blast but in the same breath, Jumbo was designed to contain a Trinity blast should that blast go less than optimally.
In a "fizzle" there is minimal nuclear reaction, typically the "nuclear" part of the explosion is similar in magnitude to the conventional explosive trigger. It's just a thermal explosion caused by a small amount of nuclear activity. Basically the critical mass undergoes a thermal expansion that spreads the fissile material out enough to dampen (and stop) the chain reaction. The resulting energy is about the same as the triggering explosion, within a factor of a couple or so. Since some fission nucs are built such that the metal containment sort of survives the pretty serious conventional explosion used to slam the piece of fissile material together, the containers tend to be fairly robust. Still, if the device goes "nuclear" at more than just a few hundredths of a percent efficiency the container is irrelevant.
A typical nuc has pretty low efficiency. IIRC, 1 to 10% is normal. Still, that corresponds to many killo
tons of TNT equivalent. That's millions
of pounds of TNT.
In the case of plutonium's bombs, it's interesting that the oft cited concern was saving the precious plutonium instead of keeping the extremely
toxic plutonium from getting spread over a big chunk of the US.