Honestly 5,000 gallons from a nuclear plant into the ocean is not all that much. When refueling occurs in a reactor outage, people aren't in there wearing full suits like in the movies. They have coveralls that have to be disposed of afterwards, but the biggest thing that protects them from the radiation is the water in the reactor vessel itself.
You could probably swim on the surface of that reactor pool and be perfectly fine.
Honestly 5,000 gallons from a nuclear plant into the ocean is not all that much. When refueling occurs in a reactor outage, people aren't in there wearing full suits like in the movies. They have coveralls that have to be disposed of afterwards, but the biggest thing that protects them from the radiation is the water in the reactor vessel itself.
You could probably swim on the surface of that reactor pool and be perfectly fine.