Nuklon is the name of two fictional superheroes in the DC Comics Universe.
Godson to Al Pratt (the Golden Age Atom), Albert Rothstein acquired his powers of super-strength and control over his molecular structure from his grandfather, a reluctant supervillain known as Cyclotron, allowing him to fight crime first as Nuklon, and later as Atom Smasher.
As Nuklon, Albert was a charter member of Infinity Inc. and subsequently served in the Justice League. He took the Atom Smasher identity shortly before the re-founding of the Justice Society of America, of which he was a charter member.
52 presents Gerome McKenna as one of the first official subjects for Lex Luthor's "Everyman Project".
Luthor's project grants super-powers to McKenna, who is given the codename Nuklon after Luthor buys the rights to Infinity Inc. from the Pemberton Estate.
So far, Atom Smasher and the new Nuklon have yet to meet.
Infinity Inc #1 (Sept 2007) reveals that, after Luthor shut down his Metagene, Gerome went into a deep state of depression and self-absorption. Gerome discovered that he has gained a new power, the ability to create a fully functional, independently thinking duplicate of himself, seemingly without control. As the series progressed, he managed to create another copy, however this version is dark and amoral, wishing to replace the original. In #8, the team were presented with new costumes and names, Gerome's being "Double Trouble". Gerome's dark double was later captured by Dr. Bud Fogel, and conditioned to be a fighter in The Dark Side Club. In the series' final issue, the dark double killed the original, gaining autonomy. However, Fogel then activated a machine that stripped all but three of the remaining Everyman subjects of their powers, and the dark double simply faded out of existence.