Not exactly what I had in mind, but pretty good. Way I invisioned Ultimate Captain Atom, his only inherent super power is that his body gives of massive amounts of heat and radiation. This makes it lethal for normal people to be around him, so he wears a containment suit to protect others. The suit is powered by the energy he generates, and aswell as sheilding others from radiation, it boosts his strength to Superman like levels and allows him to fly. He can also release the energy from his suit in focused blasts of intense heat. This version has his powers being an accident.
Another version has his powers not being an accident, but instead part of an experiment to turn a human being into a living nuclear reactor. His body produces vast amounts of heat and radiation, and to help contain it his cellular structure is made vastly more dense, giving him his super strength and invlunerability.
Doesn't matter really, but those were my ideas.