This happened twice.
They nicknamed it the "demon core," because it was easier to blame the deaths on an evil experiment rather than horribly lax safety protocols.
And then there was the case of scientist Don Mastick, who once picked up a vial of plutonium, unaware that some of the liquid inside had converted into gas. When he tried to uncork it, the vial popped open and sent plutonium spewing into his mouth. He washed his mouth out with sodium citrate and repeatedly pumped his stomach, then handed the contents to a colleague and told him to go separate out the precious plutonium. No point wasting it, right?
Mastick survived without any major health problems, though for days afterward, his breath remained so radioactive that it could affect sensitive lab equipment from across the room. Did he use his powers to briefly fight crime as a superpowered vigilante? History doesn't say, so we're forced to assume that yes, he did, and further that his name was Dr. Meltmouth.