with the number of nuclear weapons in the world now, and how old a lot are, how is it possible we’ve never accidentally set one off?

Question

Title says it. Really curious how we’ve escaped this kind of occurrence anywhere in the world, for the last ~70 years.

In: Engineering

Answer 1

One of the saving graces of nuclear weapons is that the conventional explosion to compress the plutonium sphere has to be *really* symmetric. Like really really symmetric. Plus the thingy that fires the neutrons in right at maximum compression has to be timed to within a few microseconds. Both of these things are actually pretty hard to do. If the conventional explosion isn’t symmetric, you just get a mess with plutonium blasted around, but no yield. So it’s a cleanup problem, but not much of a bang. If the neutron source doesn’t work, yet get a lot less yield and it’s probably what’s called a fizzle where yield is too small to do much.

An aging weapon having a problem is really unlikely to work correctly and will just make a mess. Bad if you are right there, but not a big deal.