Teenage Mutant Ninja Turtles (1987)

S10E2 The Beginning of the End

As Raphael, Michelangelo, Donatello, and Carter focus on bringing Leonardo back to his former self, Mung takes the opportunity to swipe all the plutonium from a local power plant. This stolen plutonium will assist Dregg in constructing a Plutonium Ray, which he plans to use to transform Leonardo into a dangerous radioactive assassin.