What stops a nuclear bomb’s chain reaction?

Question

What stops a nuclear bomb’s chain reaction?

In: 9

Answer 1

You simply keep the fissile material below critical mass, usually by keeping it in parts that are sufficiently separated or by having it be below critical density to begin with.

To start the chain reaction you either shoot one part into the other, bringing it to critical mass, or put the sub-critical material under massive pressure to condense enough that it becomes critical.