Radioactive Man

Origin

Chen Lu was a nuclear physicist in the People's Republic of China, and was ordered to find a way to defeat the Thunder God Thor, who had thwarted the Red Army's invasion of India. Secreting himself away in a laboratory, Lu exposed himself to small doses of radiation until able to withstand a massive barrage. Becoming a living "Radioactive Man", Lu displayed his new found powers to his superiors and then traveled to New York City to battle Thor. While the newly-named Radioactive Man was able to initially match Thor, the Thunder God brought his powers into play and used a vortex to transport Lu back to China, where he apparently self-detonated.

Chen later survived and was later coerced into joining Baron Zemo's original Masters Of Evil in an attempt at destroying the avengers, but failed in destroying them. Years later, Lu joined another version of the group formed by killer robot Ultron, which also met with defeat. Sometime later the Radioactive Man escaped confinement and traveled to Vietnam, where he joined Soviet villains the Titanium Man and Crimson Dynamo and formed a team called the Titanic Three.Acting as free agent crime fighters in Vietnam, the trio were duped by a con man and petty thief called the Slasher and battled four Avengers, being Thor; Iron Man; Vision and Hawkeye respectively. Once the deception was revealed the battle ended. After a humiliating defeat by Kang, the group finally disbanded when the Crimson Dynamo decided to leave fight Iron Man.

Chen later joined another incarnation of Masters of Evil led by Egghead but was defeated by Hank Pym and deported back to china.Whilst in China, the Radioactive Man worked for The Mandarin in an unsuccessful attempt to kill Iron Man.

Being sick of his constant defeats he tried to reform and joined the Thunderbolts which was comprised of former villains. The Commission on Superhuman Activities noted Lu's efforts to reform, and allowed him to assist Mr. Fantastic and Yellowjacket in building a holding prison for dissenting super-powered beings during the Civil War. 
 
After the events of the Civil War Chen continued to serve alongside the Thunderbolts in hunting down unregistered superheroes. He continued his tenure up until the Skrull Secret Invasion where he fought with other Thunderbolts aganist skrulls with the powers of the orginal Thunderbolts.  
 
In the aftermath of the invasion China recalled all super powered being back to China to help rebuild this included Chen Lu. On his return to China Chen joined the People's Defense Force.
 

Another Radioactive Man

There was another Radioactive Man in the pages of Black Panther. He was Russian. He has no known connection to Chen Lu.

Powers

The Radioactive Man can control radiation along the entire spectrum. He can emit potentially lethal amounts in concentrated blasts or across a wide area to the point of infecting entire areas with radiation posioning. He can also convert Radiation into physical strength which has helped him fight Namor , and he can also make force-fields strong enough to withstand a blow from Mjolnir Thor's hammer. He is also very intelligent and a brilliant scientist.

Alternate Realities

Earth-2182

In Nocturne's home reality Radioactive Man is a member of the Brotherhood of Evil Mutants along with Cyclops, Rogue, Blob, Hyve, White Dwarf and Beast (Not Henry McCoy).

It is not known if he is a mutant, but it's possible. 

Earth-58163 
In the House of M reality  Radioactive Man is part of the Thunderbolts who are a group of humans that fight aganist mutant tyranny. He fights alongside Baron von Strucker, Flashback, Andrea and Andreas Strucker.