system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Is there a reason that only uranium and plutonium is used in nuclear weapons? Could other radioactive elements be used just as easily?
gpt
Nuclear engineer here. 

These elements are chosen because they are fissile. 

Fissile materials have the special property that they can have a self sustaining chain reaction on their own. 

There are many elements which can fission, but only heavy elements release energy when they fission, and only a small number of these heavy elements can have a self sustaining chain reaction, and only 2 of these elements are accessible/available for use (uranium and plutonium). 


It actually has nothing to do with radiation. Uranium and Plutonium are actually very weak radiation emitters and can be held in your hand with no deleterious effects (they are more toxic as a heavy metal than they are dangerous as a radioactive material). Radiation does not cause nuclear fission reactions, however nuclear fission reactions do cause radiation, and also generate radioactive waste which emits even more radiation.