Well, about 10% of the heat a reactor creates is from the radioactive decay of fission products, so even when a reactor is “scrammed” (shutdown, no fission occu

Well, about 10% of the heat a reactor creates is from the radioactive decay of fission products, so even when a reactor is “scrammed” (shutdown, no fission occurring) you need to be able to extract megawatts of heat to keep it stable - hence you need powered pumps, access to water, condensation towers, etc.