How does the metal ball used in nuclear weapons work, and how can it be handled without constant fear of exploding?
In: Technology
When certain radioactive elements decay they release high energy neutrons, which can be absorbed by neighboring atoms and cause them to decay immediately. However, the neutrons have too much energy and aren’t likely to be absorbed, so most of the decay happens randomly from other atomic forces.
In a nuclear power plant, a mediator like water is used to slow the neutrons down so they get absorbed and cause immediate decay (releasing more neutrons). Controlling how much of the fuel is exposed to each other through the mediator controls the reaction.
In a nuclear (fission) weapon, the goal is to cause such a large burst of neutrons that even with the low chance of them being absorbed there are just so many in such a tight space that it’s inevitable, causing an uncontrolled reaction.
The fuel alone isn’t dense enough or emitting enough neutrons normally to cause this chain reaction. To get it going, an even more unstable element is smashed into the bomb’s core which releases a ton of neutrons. At basically the same time very carefully balanced conventional high explosives all around the core compress the core so that it becomes far more dense and more likely to absorb neutrons.
In a hydrogen (fusion) bomb, all of that also happens but the small fission bomb is used to compress a hydrogen pellet so much that it fuses and releases far more energy.
The uranium or plutonium core can’t undergo that chain reaction on its own.
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