In March 2011, a devastating earthquake and tsunami in Japan caused a meltdown at the Fukushima nuclear power plant.

As tens of thousands of people were evacuated from nearby towns and villages, the world waited anxiously to see whether the radioactive fallout would spread across the country, or even be carried overseas.

Unsurprisingly, in the wake of this incident, the nuclear operations of other countries have come under considerable scrutiny.

One such country is the US where more than 100 similar reactors - some of them in earthquake zones or close to major cities - are now reaching the end of their working lives.