Quote Originally Posted by bunsen_h View Post
I've held a piece of uranium, rod-shaped, about half a kilogram (~ 1 lb.) IIRC. It wasn't even warm to the touch. I don't recall if it was natural uranium or depleted. (My boss at the time had had a lot of experience with radioactive materials, and was perhaps a bit too casual about the hazards.) At any rate, a uranium elemental would cause more harm through toxicity than from radioactivity unless it was enriched, or unless one spent a long time exposed to it. Would a uranium elemental be contaminated by the daughter products: radon, radium, etc.? (EDIT: Special breath weapon, radon cloud?)
One pound of uranium isn't going to do much, no, but the thing about radioactive materials is that they possess a quality called "critical mass"- the smallest amount of material required to sustain a nuclear chain reaction.

Of course, once I started looking up some numbers, I learned that Uranium 238, the most common isotope at 99% of all naturally-occurring uranium, does not have a critical mass, and has a half life of nearly five billion years, or "roughly the age of the Earth."

Plutonium 239, however, which can be relatively easily made from Uranium 238, has a critical mass of 10 kilograms, which is a sphere almost ten centimeters in diameter. A Plutonium elemental, once killed, would almost immediately turn into a nuclear fireball that turns everything in a hundred mile radius into glass and ashes.