Asia nuclear reactors face tsunami risk

April 20, 2011 - 0:0

JAKARTA, Indonesia (AP) -– The skeleton of what will soon be one of the world's biggest nuclear plants is slowly taking shape along China's southeastern coast — right on the doorstep of Hong Kong's bustling metropolis. Three other facilities nearby are up and running or under construction.

Like Japan's Fukushima Dai-ichi plant they lie within a few hundred miles of the type of fault known to unleash the largest tsunami-spawning earthquakes.
Called subduction zones, these happen when one tectonic plate is lodged beneath another. And because the so-called Manila Trench hasn't been the source of a huge quake in at least 440 years, some experts say tremendous stresses are building, increasing the chances of a major rupture.
Should that happen, the four plants in southern China, and a fifth perched on Taiwan's southern tip, could be in the path of a towering wave like the one that struck Fukushima.
""We have to assume they'll be hit,"" said David Yuen, a University of Minnesota professor who has modeled seismic probabilities for the fault. ""Maybe not in the next 10 years, but in 50 or 100 years.""
Asia, the world's most seismically charged region, is undergoing a nuclear renaissance as it struggles to harness enough power for its huge populations and booming economies.
But China, Taiwan, India and several other countries frantically building coastal facilities have made little use of new science to determine whether these areas are safe. At least 32 plants in operation or under construction in Asia are at risk of one day being hit by a tsunami, nuclear experts and geologists warn.
And even when nations have conducted appropriate seismic hazard assessments, in many cases they have not shared the findings with the U.N. International Atomic Energy Agency, leaving experts frustrated and in the dark.
""It's pretty astonishing to a lot of us that so little priority is placed on the work we do,"" said Kerry Sieh of the Earth Observatory of Singapore, who has studied and written about the Manila Trench, where pressure has been building for millions of years.
He is among those who say it is only a matter of time before it snaps.
In assessing the tsunami risks to nuclear power stations, scientists focus on their proximity to subduction faults, volcanoes and areas frequently hit by underwater landslides — all of which can trigger seismic waves. Because giant tsunamis recur, they also look at historic and scientific records, going back up to 4,000 years if possible.
The greatest threat comes from the subduction faults crisscrossing the globe, some far from the minds of policymakers, nuclear industry officials and the public because it has been so long since they exploded.
In places where tectonic plates that form these faults are ""coupled,"" or stuck together, the stresses are the biggest, especially if centuries have passed without a major energy-releasing earthquake.
When the strain eventually forces one plate to pop up or dive under the other, the resulting temblor can spawn mammoth waves like the one that struck off Japan's northeast coast on March 11, triggering the nuclear crisis that has carried on for more than a month.
While there is some ""coupling"" at the Manila Trench, there is debate about just how much. Scientists say more research needs to be done to determine if pressure is building and along which segments.
A computerized simulation by Yuen's students shows a magnitude-9.0 quake along the Manila Trench sending waves racing along the South China Sea, before slamming Taiwan's southern shore 15 minutes later. The tsunami reaches China's southeast coast in around two hours. It also strikes Hong Kong, which sits just 30 miles from the nearest nuclear plant — close enough to see increased radiation levels if a plant were to be damaged by a Fukushima-like event.
Scientists paint a worst-case scenario in which waves 15 to 24 feet high (5 to 8 meters) could strike the plants in China and Taiwan.
This March 11, 2011 photo made available April 16, 2011 shows the Ling'ao Nuclear Power Plant, one of two nuclear stations in Daya Bay, near Shenzhen in southern China. (AP Photo)