And once their automated safety systems began to fail without human supervision, there would be meltdowns across the planet, rendering many regions simply uninhabitable.
At this point, you might be wondering HOW in the name of Darwin do these animals manage to not only survive, but to thrive in sometimes uninhabitable waters?
Extremely radioactive material will kill living things very quickly, and a large area several kilometers around the crater is now uninhabitable, as is everywhere for hundreds of kilometers downwind.