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Nuclear Mutant for Godzilla
Radiation-Induced Superpowers for Hulk
Maybe also look at Phlebotinum du Jour if you're thinking of sci-fi works from a certain era which have a lot of radiation tropes.
Edited by FerrousFaucetSee also Atomic Hate and Radioactive Tropes (formerly I Love Nuclear Power) for indexes collecting tropes in this vein.
Genre-wise, these works generally fall into the overlap of Sci-Fi Horror (esp. the hubris of overreach form) and Survival Horror (both realistic and Weird Science radiation turn the outside world into a hostile environment to humans)

Subgenre of horror centered around the fear of the atomic or nuclear radiation or weapons. This can range anywhere from the horror elements being a metaphor for atomic radiation/weapons to the story literally being centered around atomic radiation/weapons.
Examples of this include Godzilla (1954) and certain Hulk comics.