The Nuclear Regulatory Commission authorized an updated study of nuclear plant risk from a blackout. The study was authorized after a massive power outage in August 2003 darkened the Midwest and Northeast and caused nine nuclear plants to lose power.

The study, by the Idaho National Engineering and Environmental Laboratory, considered total loss of power at 103 nuclear reactors because of electrical grid blackouts coupled with failure of the plants' backup emergency diesel generators.

The study said the potential for a blackout causing core damage at the southern Wake County plant is one in about 61,000 years, said Edwin Lyman, senior staff scientist of the Union of Concerned Scientists. The Washington-based nonprofit agency advocates on energy and environmental issues.

Core damage means that the metal tubes holding the fuel are breached and start releasing radioactivity -- though not necessarily into the atmosphere.

The reactor vessel, which holds the fuel rods, and the concrete containment dome also would have to be ruptured before radioactivity actually escaped.

"Right now, the threat is at a higher risk than it should be," said Dave Lochbaum, a nuclear safety engineer with the Union for Concerned Scientists. "If I lived five miles from the plant, I wouldn't pack up my family and head out. But I would want to get the plant fixed so that that problem never occurred."

Rick Kimble, a spokesman for Progress Energy, said the report was a still a draft and the utility had not seen it.

"We've got some guys who are going through the report," he said. "Until we do that, we are not going to comment."

At nuclear plants overall, the study said that the risk of core damage from loss of power was lower than previous estimates, generally due to better emergency generator performance.

Lochbaum said Harris ranked high in risk because the plant has fewer backup diesel generators than some plants, and a generator can be out of service for longer periods -- up to 14 days. Lochbaum said the risk factor could be lowered simply by not keeping backup generators down during seasons of unstable weather, such as hurricane season, when there is a greater likelihood of power outage.

Lochbaum and NC WARN, a Durham-based grass-roots nuclear watchdog group, cited the NRC blackout study and unresolved fire and equipment safety issues common at many nuclear plants, including Harris, to argue that no new nuclear reactor should be built.

"We need to solve the problems, and the oversight problems that allowed them to occur, before discussing new reactors," Lochbaum said.

Progress has not committed to building a nuclear plant but estimated that it will need additional power generating capacity by 2017. Based on that timetable, the utility would need to start building a plant in about 2010, Kimble said. It has not announced whether it would be coal-fired, nuclear or another technology.

Progress Energy has joined a consortium of about a dozen utilities that filed a proposal with the Department of Energy to share the cost of preparing a licensing application to get a new nuclear plant under construction by 2010.

Staff writer Wade Rawlins can be reached at 829-4528 or wrawlins@newsobserver.com.