Safety enhanced in new generation of reactors

Mar 16 - McClatchy-Tribune Regional News - Thomas Olson The Pittsburgh Tribune-Review

New nuclear reactor designs would have stood a much better chance against the type of natural disaster Japan's power plants just encountered, said nuclear engineering experts on Tuesday.

"The main thing that distinguishes newer reactors is the companies have all looked at new designs from the standpoint of how to simplify the plant so there's less that can go wrong," said John Metzger, a nuclear engineer and director of the University of Pittsburgh's nuclear program.

The leader among these so-called "generation three-plus" nuclear reactor designs is Westinghouse Electric Co. in Cranberry. The company is supplying China with four of newly designed AP1000 nuclear reactors, whose "advanced passive" features enhance efficiency and safety.

Westinghouse employs about 3,300 people in the Pittsburgh region.

The first AP1000 reactor is to come online in 2013. Six more of the Westinghouse reactors are under contract to be built at utilities in Georgia, South Carolina and Florida.

A primary safety feature of the AP1000 reactor is its system of cooling the reactor core in the event the uranium fuel overheats, said Ed Cummins, Westinghouse vice president and chief technologist for new plant technologies. If there's an accident, water is released from a tank above the reactor vessel, instead of water being pumped there.

"The biggest difference between the AP1000 and current reactors is that (the AP1000) doesn't need diesel power or the electric grid or batteries to keep the plant safe," said Cummins.

The AP1000 also contains 87 percent less cable, 83 percent less piping, 50 percent fewer valves and 36 percent fewer pumps than the previous generation of reactors, according to Westinghouse. "It's safer because you don't need all the pumps and valves," he said.

General Electric Co., through its GE/Hitachi Nuclear Energy business has designed a more simplified nuclear reactor, said Metzger, with fewer valves and components.

In a statement, GE noted Japan's 9.0 magnitude earthquake was the earth's fifth-largest on record and that its reactors "performed as designed and initiated safe shut down." The company also stated its reactors have "a proven track record of performing reliably and safely for more than 40 years."

GE has about a 10 percent share of the world's nuclear reactors, second behind Westinghouse's 45 percent. GE declined to be interviewed yesterday, including about its current generation of nuclear reactors.

"Most of the new plants have some form of natural circulation of coolant, without actively having to pump it," said Metzger.

"Areva has a similar plant on drawing boards in France and Finland," said Metzger, referring to the French nuclear power company.

Experts believe the General Electric reactors in Japan failed because a tsunami wiped out the main pumping power and the diesel-powered back-up, said Metzger.

The Nuclear Regulatory Commission sets the design standards for nuclear power reactors in the United States and licenses power plant operation.

"We require that they be designed to take into account the most severe natural phenomena ever historically recorded in that area," said Diane Screnci, spokeswoman for the NRC's regional office in King of Prussia.

"They are analyzed for whether they can withstand the most severe earthquake or hurricane or tornado ever reported for that area, out to 200 miles" of a plant site, she said.

Westinghouse is awaiting approval from the NRC for redesigns of its AP1000 nuclear reactor for use in the United States. The agency directed Westinghouse in 2009 to fortify the reactor's outer shell building to sustain the impact of a jetliner, earthquake, hurricane or tornado.