06/11/03

Design flaws uncovered in a part of the emergency core cooling system at the Davis-Besse nuclear power plant have prompted the Nuclear Regulatory Commission to ask the operators of similar reactors nationwide to prove their emergency cooling systems will operate in a crisis.

The NRC yesterday issued a bulletin to owners of 68 other high-pressure reactors. The agency wants to know within 60 days why the utilities think the emergency sumps in the reactor containment buildings are capable of handling the thousands of gallons of coolant that would explode out of a reactor during a major accident.

The NRC has been aware for nearly two decades that debris blown about the containment building by a high-pressure geyser of coolant from a pipe break or other rupture could clog the sumps - and starve emergency pumps pushing the coolant back into the reactor core. The agency and industry groups have researched the problem and possible fixes for years without coming to a definitive conclusion, partly, say critics, because of the high cost of redesigning the sumps and partly because no plants are identical.

Agency researchers last August concluded that debris screens on sumps of the general design found in most reactor buildings could either clog or collapse under the weight of debris following an accident. And a Los Alamos National Laboratories risk study for the NRC released in February suggested strategies to reduce the risk of a catastrophe caused by sump failure.

But it was the work of Davis-Besse's engineers that added urgency to the need to take action, said David Matthews, the NRC's director of regulatory improvement programs.

Davis-Besse's engineering study detailed the weaknesses of the Toledo-area's plant's sump in a thorough analysis last December that predicted the sump's debris screen would clog and the emergency pumps would fail in a major accident.

And this spring, the company declared that a pair of emergency pumps designed to force water back into the reactor before its one-ton-per-square-inch pressures are blown off could, under certain conditions, clog even if the sump's debris screen did not.

Because there is no backup system to the sump and its emergency pumps, a failure of any part of the system could lead to a meltdown of the reactor's nuclear core - challenging the reactor building's ability to keep the radioactivity out of the environment.

"When you get a plant declaring it themselves, you have sufficient information [for a bulletin], said Matthews. Before that, all arguments were theoretical, he said.

Davis-Besse not only declared its sumps a major safety problem. Plant owner FirstEnergy Corp. had its engineers and contractors completely redesign and rebuild Davis-Besse's sump for $3.8 million, expanding the surface area of its debris filters from 50 square feet to about 1200 square feet, said spokesman Todd Schneider. "Our new design is cutting-edge."

Yesterday's bulletin asks each plant owner whether an engineering analysis has been done, how thorough it was, and whether top officials can swear under oath that the sumps and related equipment will work after a major accident.

Plant owners who have not done a rigorous study, or whose examinations turned up design problems, must tell inspectors what their staffs are doing to compensate for the shortcomings while a permanent fix is developed.

The speed with which the NRC is moving has apparently surprised the industry, which is still developing a model sump analysis for plant owners to use in diagnosing their sump problems, said John Butler of the Nuclear Energy Institute, the industry's lobbying arm.

He said until recently the plan was that the NRC was not going to issue a bulletin but instead a less hard-nosed "generic letter" - bureacratese for a typical way of alerting plant owners of a problem and requesting possible solutions, a process that can take from months to years.

NRC engineers are now working on that letter, and the agency will issue it in a few weeks, said Matthews. It will ask for suggestions about how to permanently solve the sump problem. In the meantime, the bulletin will provide the agency with the plant-specific information it needs, he said.

The letter-and-comment strategy could take months, said Paul Gunther of the Nuclear Information and Resource Service, a critic of the NRC.

"We remain concerned that the pace moves like molasses," Gunther said. "They have talked about this for at least a decade. It's time for action, not more talk."

For complete coverage of Davis-Besse, go to www.cleveland.com/davisbesse/

To reach this Plain Dealer reporter:

jfunk@plaind.com, 216-999-4138