> I have had a lot of oh shit moments in my days, but none gets close to dropping the plutonium onto the uranium and nearly detonating a nuclear payload. Not p

> I have had a lot of oh shit moments in my days, but none gets close to dropping the plutonium onto the uranium and nearly detonating a nuclear payload. Not possible for a plutonium device, and this is why the implosion method was so technically challenging. The plutonium must be transitioned from subcritical to supercritical very, very fast to achieve any significant nuclear energy release. In the final design, shaped plastic explosives, chosen for their very high velocities, were used to compress the plutonium from all directions simultaneously, very fast. Then, after the compression phase is complete, a carefully timed burst of neutrons triggers the nuclear fission event.