As aftershocks from China's devastating earthquake continue to cause havoc, atomic safety experts from around the world are preparing to meet in Japan this month to scrutinize seismic standards at nuclear plants. Because they contain lethal sources of radiation, the plants are designed to withstand major earthquakes and shut down safely. But are the standards adequate?
Asia is leading the renewed global push into nuclear power for generating electricity as China, Japan, South Korea, India and other countries seek to cut global warming emissions and improve their energy security by reducing reliance on fossil fuels like oil, coal and natural gas. Asia's nuclear construction will account for well over one third of the world's total between now and 2020, according to the World Nuclear Association.
More than 110 power reactors are generating electricity in six Asian countries, with dozens more under construction or planned in Northeast, Southeast and South Asia, including Indonesia. There are also more than 50 nuclear research reactors operating in 14 Asian states. The only advanced economies without them are New Zealand and Singapore.
Japan already generates around 30 percent of its electricity, and South Korea 45 percent, from nuclear power. Japan plans to raise this figure to over 40 percent by 2017 and South Korea to 60 percent by 2035. China generates less than 3 percent of its electricity from nuclear power but has announced a massive expansion of capacity over the next two decades. India, too, has ambitious nuclear plans.
Most critics of this program focus on proliferation risks, operational safety standards and the management of highly radioactive waste from spent reactor fuel. But in Asia - a region prone to shattering earthquakes, volcanoes and tsunamis - a continuing challenge for nuclear power regulators and managers will be seismic hazard and the associated risk of catastrophic radiation leakage. The May 12 earthquake in China that destroyed large swathes of southwestern Sichuan province killing more than 67,000 people, is a reminder, if one were needed, of how suddenly a tremor can strike and how much damage it can do.
Worldwide, it is estimated that some 20 percent of nuclear reactors are operating in areas of significant seismic activity. Many are in Asia. For example, because of the frequency and magniture of earthquakes, particular attention is paid in Japan to seismic shock in the siting, design and construction of nuclear plants. Until recently, the systems for assessing, and coping with, the impact of seismic shock appeared to be sufficient.
When an earthquake that measured 7.2 on the Richter scale flattened parts of the Japanese city of Kobe in January 1995, none of the nuclear power reactors within 200 kilometers of the epicenter sustained any damage and those running at the time continued normal operations. Four years later, when a shallow magnitude 7.6 earthquake in central Taiwan killed thousands, it caused three reactors in the north of the island to shut down automatically. They were cleared to restart two days later.
In August 2005, a magnitude 7.2 earthquake struck Honshu in northeastern Japan, triggering automatic shutdowns of three reactors. While no damage was recorded in any sensitive part of the plants, they were only phased back into operation between January 2006 and May 2007. Then, in July last year, nature unleashed another blow. A magnitude 6.8 quake shook the coastal area of Niigata, on the north-west coast of Japan.
The epicenter was only 16 kilometers from the Kashiwazaki Karima nuclear plant. This is the world's biggest nuclear power complex, with seven reactors capable of generating nearly 8,000 megawatts of electricity. Four shut down automatically. The other three were not operating at the time. There was a very small radioactive release, but one said to be well below public health and environmental safety limits.
Detailed inspections showed that the main reactor and turbine units were structurally unaffected, and that there was no damage to the nuclear fuel in the reactor cores. But the episode has nonetheless raised some disturbing questions for nuclear safety experts and regulators.
One is how Japanese officials came to approve the siting of the plant in the 1970s very close to what is now perceived to be a serious geological fault line? Another is that the United Nations nuclear watchdog, the International Atomic Energy Agency, found in a report earlier this year that the July 2007 earthquake "very significantly exceeded" the level of seismic activity for which the plant was designed.
Appropriately, the international conference on the seismic safety of nuclear power plants is being held at Kashwazaki in Japan from June 19-21. It is being organized by the IAEA in cooperation with Western and Japanese nuclear experts. In Japan and other earthquake-prone countries, systems and standards for protecting reactors against seismic shock are regularly reviewed and upgraded. But this is an arcane science that is not always predictable.
Meanwhile, Japan is counting the cost. The world's biggest nuclear power complex remains shut. The plant's operator, Tokyo Electric Power Company, has reported that the closure cost it about $US5.6 billion in the financial year to March, mainly from increased fuel costs in coal- and gas-fired plants to replace the lost nuclear generating capacity. There have also been delays in commissioning several new nuclear reactors in Japan as more stringent seismic conditions are applied.
(Jakarta Post.com)
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