“I think you are referring to a dirty bomb which is not a nuclear device.”
Each weapon has an element of refined radioactive material as the cornel that is intended to implode and reach critical mass. While it’s unlikely that this element will reach critical mass without being actually “fired” they are radioactive and therefore dangerous.
“they are radioactive and therefore dangerous.”
Having slept many hours within inches of nuclear warheads I can confirm they are not very radioactive.
Plutonium in itself is quite dangerous. The isotope Plutonium-239 has a half life of several thousand years. If you inhale plutonium dust it’s lights out. Slowly. You don’t want to be anywhere near an explosion like if a conventional bomb hit a nuclear missile and dispersed the plutonium.