Why do we use uranium and plutonium for nuclear weapons and reactions?

Question

I would think that neutrons can break up any nucleus apart. Why not just use aluminium or iron. Is it because of E=mc^2 ? Greater mass equals greater energy? Would a bomb made of another material be less radioactive?
TIA

In: 30

Answer 1

Simplest reason is two part.

1 st: is the uranium and plutonium naturally give off neutrons as they radiative decay. Granted they aren’t the only ones

2 nd: The waste from the nuclear power plants is closer to the enriching level needed for nuclear weapons. So it gave the government a jump start in building weapons.