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Emergency core cooling system was “seriously degraded” for a year, greatly
increasing reactor risk in early 1990s. Group demands more openness.
DURHAM, NC – A year-long, high risk condition at the Shearon Harris nuclear plant has been uncovered by a nuclear watchdog in Washington after remaining secret for 15 years. A design flaw in the reactor’s emergency cooling system caused valve and pipe failures that rendered the system inoperable, and unable to respond if called on to prevent a meltdown. The problem went unnoticed until a refueling outage in 1991.
This “precursor event” to a nuclear accident ranks among the highest risk incidents in the U.S. since the 1979 partial meltdown at Three Mile Island, according to Nuclear Regulatory Commission criteria. Agency investigators concluded: “The flow rate of water required to neutralize the effects of ‘design basis’ accidents assumed in the licensing analysis would not have been attained.” (emphasis added)
The discovery was made by Greenpeace’s Jim Riccio while conducting research for a report to be released Monday on U.S. nuclear accidents and near-misses since the 1986 Chernobyl disaster. The Harris failure stemmed from a flaw by plant designer Westinghouse. After Westinghouse alerted several nuclear plants about the defect, Harris owner CP&L attempted to correct the problem, but unknowingly made it worse.
Riccio noted that NRC calculated the year-long Harris failure as having the same risk for a meltdown as did the 2002 near-miss at Ohio’s Davis Besse plant, when a large hole was discovered in the reactor vessel. The NRC calculated the Harris failure as increasing the risk of a reactor meltdown by up to 1,000 times over normal. If a rupture in primary cooling system valves or pipe connections had occurred during that year, the emergency cooling system would have been triggered, but unable to protect the reactor core from overheating and releasing large amounts of radioactive materials.
Durham-based watchdog group NC WARN said today the discovery was further indication that Progress Energy needs to be more open with the public about problems and how the utility is correcting them. “This is dramatic evidence that major system failures do occur at nuclear plants,” said Jim Warren, Executive Director of NC WARN. “It shows that the utilities and NRC do not have everything under control, and that they gamble on the public not finding about these problems – instead of explaining them.”
Warren also questioned why the system failure persisted for a full year without CP&L rechecking the correction it had made after Westinghouse alerted them about the defect. NC WARN has detailed other Harris design flaws that have remained uncorrected for years, according to Warren. Next week, the group will publish a report on serious and ongoing safety problems at Harris, along with other reasons Progress should abandon plans for new reactors at the southeastern Wake County plant.
CP&L was recently renamed Progress Energy, and in January selected Westinghouse to possibly build two more reactors at Harris. Westinghouse is still altering its new design in an effort to entice some utility to build a new plant and revive the fading industry. “Cost-cutting pressures are pervasive in this industry,” said Warren. “This near-miss is another reason the public and local governments should not be shut out during the licensing process for new reactors.”
Union of Concerned Scientists’ David Lochbaum, a technical advisor for NC WARN, said the Harris failure further belies industry claims of being safer over the years “just because they haven’t melted down another reactor since Three Mile Island.” He said there’s a common misconception that only explosions, such as the Chernobyl disaster, can lead to large releases of radiation. During a reactor or steam generator accident, high pressure inside the containment building can last for hours or days, which would push large amounts of radioactive gases through scores of openings and seals in the building’s walls.
NC WARN has urged Progress for years to be more forthcoming about problems at its plants – and whether they are being corrected – instead of the watchdog group and its allies having to discover and expose them.
“Public safety shouldn’t depend on cat and mouse games about problems, nor on watchdog groups having to dig out information from NRC’s Byzantine data system where everything is written in nukespeak,” added Warren. “We call on CEO Robert McGehee to instruct his people to be forthcoming about problems that arise, and whether and how they are being corrected. And we want to know what other skeletons there might be in the Shearon Harris closet.”