Comment by dzhiurgis
When I visited one (decommissioned one in Ignalina, Lithuania where they filmed Chernobyl series) they said the radiation levels are higher than neutral/ambient, but lower than in city because all the concrete is slightly radioactive.
Yeah, that is my understanding too. Usually the inside the plant the radiation is lower than many other industrial places too. But my concern is when things go wrong (like flooding in Japan) the radius of which it can effect can be quite large and take a long time to recover.