When the Japanese tsunami damaged the Fukishima nuclear reactor there were 172,000 people living within the 30km danger zone.
But recent analysis by Nature and Columbia University, New York, has discovered that other facilities around the world are located in highly populated areas where a similar accident would put many more residents at risk.
Currently, over two thirds of the world’s nuclear power plants have 170,000 or more people living within 30km, and at 21 plants the number is over a million.
To put that figure into perspective, the US National Terror Alert Response Centre predicts that the fallout from a major explosive blast within a plant would kill everyone within 30km.
Top of the danger list is the 125MW Kanupp nuclear power plant in Karachi, Pakistan, which has an astonishing 8.2 million people living within a 30km radius of its boundaries.
What is more worrying is that the plant lies in close proximity to the Allah Bund Fault line, responsible for the magnitude 7.7 Indian Bhuj earthquake in 2001.
Next in terms of vulnerable population is the much larger Kuosheng plant in Taiwan, which generates 1,933MW and has 5.5 million people inside the 30km zone. Taiwan sits at the convergence of two tectonic plates has a number of fault lines.
Major power cuts and magnitude 6 earthquakes have been experienced here, but worryingly Kuosheng has been constructed to withstand seismic activity of only magnitude 7.
The initial quake that destroyed Fukushima was rated at magnitude 9.
The age of these plants offer little comfort as both are over 30 years old.
However Nature News comments that a “culture of security” is more important than the age of the plant; Chernobyl had only been in operation for two years at the time of the worst nuclear accident in history.
An older plant in a country with stringent safety protocols might afford local residents greater peace of mind - but until this year, Japan’s nuclear safety record was among the best in the world.