Onagawa's plant was high enough above sea level to survive the tsunami without enormous damage.

ECONOMIST: Banyan

It isn't known if operator error played a role, as it did three decades ago at Three Mile Island, but it's clear the earthquake exceeded the level for which the plant was designed.

WSJ: Nuclear Industry Likely to Reassess Safety Systems

Duke Energy spokeswoman Rita Sipe said Duke Energy had detected trace radioactive elements, likely to have originated from Japan's Fukushima plant, in North Carolina and South Carolina -- but at a level "far below" reporting requirements.

CNN: Japan's nuclear contamination spreads to more U.S. states

The Sellafield plant is the UK's largest and most hazardous nuclear site, storing enough high and intermediate level radioactive waste to fill 27 Olympic-sized swimming pools.

BBC: Sellafield inspection after 'intolerable risk' report