A metallic element in nuclear weapons?

Answer 1

There are a few:

Plutonium or Uranium (either, or both, depending on the weapon)

Beryllium

Gold

Steel

Aluminum

Boron

Lead

Copper

Older style or more primitive weapons may contain polonium in the initiator.

Answer 2

Uranium is a metallic element commonly used in nuclear weapons due to its ability to undergo fission, releasing large amounts of energy. Another metallic element used in nuclear weapons is plutonium, which is also fissile and can sustain a chain reaction.