Originally, Radion was defined as the only survivor of a nuclear disaster that altered his body, giving him radioactive powers. Along with his friend, the Protector, they both tried to kill Superman, unsuccessfully.
His posterior appearance was against the Supergirl Cir-El, using a suit than give him nuclear superpowers. However, Cir-El throw him to a futuristic nuclear reactor, which mutated him and gave him natural powers.
He later would join Neutron to try to kill Clark Kent, unknown to them, was powerless.