While the Japanese tsunami has reignited the concerns over nuclear power, one thing is clear – the rules governing the location of their construction are sure to change. One would argue that the construction of a nuclear power plant in a seismically unstable region was always a cause for concern, but Michael C. Constantinou, PhD, professor of civil, structural and environmental engineering at the University at Buffalo has said that the next generation of nuclear power plants and other energy facilities will be greatly influenced by the lessons learnt from the recent tragedy.
According to Constantinou, it is possible to seismically isolate an entire facility on a concrete platform, however it is much more “technologically complex”.
“If a nuclear reactor is built at a site where a 30-foot tsunami wave is possible, if it comes, it is going to have a significant effect, there is no way to control for that,” says Constantinou, a structural engineer, and researcher with UB’s Multidisciplinary Center for Earthquake Engineering Research. “The only way to prevent the situation is to build the plant further inland, to seismically isolate it and, perhaps, to elevate it.”
This sort of caution has been implemented with Russia’s oil and gas platforms in the North Pacific near the Sakhalin Island. They lie several hundred miles north of the epicenter of the March 11th Japanese earthquake.
“These platforms sit on concrete bases on the ocean floor with legs that are about 80 meters tall, and the structure on top of the platform is another 20 stories high; the entire structure weighs some 30,000 tons,” he explains.
“Conditions there are extreme,” he added. “It is a multi-hazard environment, where one hazard can worsen the effects of another. The platforms are designed to withstand, without failure or significant effect, major earthquakes, ice forces on platform legs where giant slabs of ice two meters thick can form, temperatures as low as -40, blasts and very large waves, on the order of 10 meters above the ocean’s surface, which only may occur once every 10,000 years, and waves in combination with ice slabs,” he says. “They are very difficult structures to design.”
Constantinou says that steel ductile bearings can cope with very low temperatures and which have a large displacement capacity as well as a capacity to carry such large loads. He says they are the only ones suitable for the extreme conditions encountered in the North Pacific.
“It wouldn’t be possible to use elastomeric — rubber — bearings, which are very frequently used in Japanese buildings,” Constantinou explains. “At those very low temperatures, the rubber bearings become brittle and can shatter like glass. Also, these loads and displacement demands are too large for elastomeric bearings.”
Here’s a better idea – just don’t build potentially hazardous power plants and facilities in seismically unstable regions! You wouldn’t build one in San Francisco…
via Phys Org
Photo credits Joe Zlomek