Quake Question #12: Can Nuclear Reactors Survive Blackouts?

Readers ask: Are there any commercial nuclear plants that, when deprived of all electric power for a day, don't self-destruct and blow radiation?

Science answers: All of the most up-to-date designs of reactors, the so-called Generation III+, claim to be able to handle power outages, which are the main problem at Fukushima, some for up to 3 days. They do this by circulating cooling water via convection, rather than pumps, and top up the coolant with tanks positioned above the reactor, so gravity does the pumping work.

Some rely on pumps powered by steam from the reactor. All of them have multiple layers of automatic safety systems and their operators claim that they can theoretically walk away from them and the reactors will remain safe. All would require backup generators to keep control and instrumentation running, or at least batteries. It is impossible to make any such complex systems 100% safe from accidents, of course, but modern machines would cope with a Fukushima-style accident much more reliably.

For a complete list of quake questions and answers, see our Quake Questions page. For our complete coverage of the crisis in Japan, see our Japan Earthquake page.