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Supposedly static electricity could trigger the detonator in a nuclear weapon. There was a near accidental ignition during the development of "the Gadget" and my understanding is that the ignition system was virtually unchanged for decades.

https://books.google.com/books?id=lJ6JDQAAQBAJ&lpg=PA41&ots=...



Lightning bolt, maybe. Static electricity, no way. The detonators used are exploding-wire devices. They're just hugely overloaded resistors.[1]

Regular detonators have a primary explosive which is triggered by a modest electric pulse. The primary explosive detonates and its energy detonates the secondary explosive. Those can go off by accident, cook off, etc.

The ones used in nuclear weapons are just inert wires. Without a hulking big electrical pulse (about a megawatt for a microsecond, which is one joule) they can't do anything. A big capacitor bank is required to fire such things. It's done this way because all the detonators have to go off within nanoseconds of each other to get the symmetrical implosion squeeze to work. Otherwise the thing just blows itself apart without a nuclear reaction. That's happened a few times in plane crashes.

Newer (post-1950s) nuclear weapons don't even have a full critical mass in them. The core is squeezed down by the implosion to achieve criticality at a density higher than the normal density of the material. Without a symmetrical implosion, not much happens.

This physics makes for a much safer device. It's why nobody has ever had one go off by accident.

(The Hiroshima bomb, though, was very unsafe. It was a gun bomb, basically a 5-inch gun with conventional detonators and propelling charge. The crew of the Enola Gay was told that if they had to return to base without having dropped the bomb, drop it in deep water. Don't try to land with it. A crash or fire on landing probably would have detonated the device. That design was only used once.)

[1] https://en.wikipedia.org/wiki/Exploding-bridgewire_detonator


What design was used for bombing Nagasaki?


Plutonium implosion bomb.[1]

[1] https://en.wikipedia.org/wiki/Fat_Man




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