|Restarting a Reactor With a
By JOHN SULLIVAN
Published: December 12, 2004
http://www.nytimes.com/2004/12/12/nyregion/12salem.html (must register to view original article)
Managers of the Salem nuclear power station want to restart a troubled reactor later this month, even though New Jersey regulators have objected and an internal company report warn that flaws in a critical pump could cause an accident.
Restarting the reactor at the giant plant in southwestern New Jersey will require the approval of federal regulators. Officials of the plant's operator, P.S.E.G. Nuclear L.L.C., said that restarting the plant would pose no danger to the public and that contingency plans had been drawn up should the pump fail.
The first serious problems with the pump, called a recirculation pump, were raised in an internal report written by company engineers in April 2003. The pump helps cool one of the three reactors at the nuclear power station, about 10 miles south of Wilmington, Del.
Last month, a second engineering team concluded the pump's steel drive shaft was probably cracked, noting that, at certain speeds, the pump bangs "like a freight train." And, an advisory from the reactor's manufacturer, General Electric, said the pump has run far longer than it should without a drive shaft inspection.
One internal company report warns that if the pump burst, it could cause an accident by spilling cooling water from the reactor vessel. The company says this type of accident is highly unlikely. Officials said such an accident would not endanger the public, but it could flood the gigantic building that surrounds the Hope Creek nuclear reactor with radioactive water.
"We would cool the plant down, and we would go in and fix it," said A. Christopher Bakken III, president and chief nuclear officer of P.S.E.G. Nuclear.
Top managers at Salem, as a result, have not replaced or fully repaired the pump, and they have concluded that it can be safely operated in the short term. With the company planning to restart the Hope Creek reactor - it was shut down for repairs following an unrelated emergency in October - company officials say they are prepared to use the pump for another 18 months.
"I would not authorize start-up nor would I allow operation of Hope Creek if I had any doubts about the operational safety of this system or any major plant system," Mr. Bakken said in a written statement.
New Jersey's top nuclear regulator, however, has disputed the decision, arguing that the pump should be repaired before the reactor restarts. Other experts have said the pump is so important - and the potential consequences of its failure so serious - that repairs are required.
"We have advised Chris Bakken that we thought they should replace it," said Jill Lipoti, the New Jersey Department of Environmental Protection's assistant director for radiation protection. "But we have no regulatory role to tell them to shut it down and do so."
That authority rests with the United States Nuclear Regulatory Commission, which now has inspectors reviewing the condition of the plant. Commission officials must sign off on the operation of the pump before the Hope Creek reactor is allowed to restart. Diane Screnci, spokeswoman for the commission's regional office in King of Prussia, Pa., said the agency was reviewing data supplied by P.S.E.G. and would not comment until the review was completed.
The Union of Concerned Scientists, a nuclear watchdog organization in Washington, has called on P.S.E.G. to replace the drive shaft. David Lochbaum, a nuclear engineer with the organization, said there was ample evidence that the pump was damaged and that there was no reason to delay repairs. "The place is shaking itself apart," he said.
The story of the Hope Creek pump is unfolding against a backdrop of chronic problems that P.S.E.G. acknowledges have plagued the station for years. Salem, the country's second largest nuclear power plant in terms of electric generation, supplies electricity to more than two million customers.
But it has recently drawn the ire of regulators for maintenance problems. A nine-month federal investigation this year uncovered problems from a leaky generator to malfunctioning water pumps. Some employees also said they were reluctant to report problems because they feared retaliation from supervisors.
After the investigation finished this summer, regulators placed the plant under increased scrutiny.
The company has committed to spend millions of dollars to fix the problems, both by replacing equipment and ensuring that workers are free to complain without retaliation. In a public meeting on Dec. 2, N.R.C. officials said P.S.E.G. had made notable progress, although more improvements are needed.
The Hope Creek recirculation pump did not figure in the recent federal investigation, although questions have surrounded its operation for several years. The recirculation pump, which is connected by pipes to the Hope Creek reactor vessel, helps move water through the core to increase the reactor's efficiency.
The water level is critical because it helps generate power and cools the fuel inside the reactor. The plant can safely shut down even if the recirculation pump stops, but it cannot operate long without the pump.
"The recirculation pump is an important component of the plant's cooling system and, therefore, is an important safety component," Mr. Bakken said in a recent statement.
Workers first called attention to the pump because parts called seals were wearing out far faster than normal. The seals, which help stop water from spilling from the pump, are supposed to last six years, but they were wearing out every 18 months.
Workers also reported that the pump leaked radioactive water, according to an internal company report. In fact, the report says, it leaks so much that it has forced operators to shut down the reactor at times to avoid exceeding federal limits.
Also, engineers found that pressure waves from the pump had been rattling nearby equipment, causing valve handles and wheels to fall onto the floor. For years, workers have simply screwed the parts back on, Mr. Bakken said. He said the pressure waves were not related to problems with the pump's drive shaft, but were caused by a different part of the pump.
After workers' reports, P.S.E.G. assigned a team of engineers to examine the pump and recommend repairs. In April 2003, the engineers concluded that the steel drive shaft that runs the pump was bent, causing the machine to vibrate every time it rotated. Their report recommended that managers replace the shaft when the reactor was off line for scheduled repairs this fall.
Managers were preparing to shut the reactor down for repairs when a broken steam pipe forced the reactor operators to conduct an emergency shutdown on Oct. 10. During that shutdown, a critical safety system used to blast water into the reactor failed. P.S.E.G. recently said that the failure was caused by workers using the wrong type of lubricant on a pump - unrelated to the recirculation pump - that powers the system, causing the other pump to seize up at a key moment.
After the emergency, the plant remained closed for scheduled repairs. Mr. Bakken then hired the engineering firm Sargent & Lundy to evaluate the recirculation pump.
The firm concluded that the recirculation pump was safe to use for 18 months longer, but the engineers warned that this could change rapidly. In the report, Sargent & Lundy recommended that P.S.E.G. add sensors to the pump and monitor them carefully. If the vibrations increase, Sargent & Lundy said, the "window between the rise and potential shaft failure is expected to be small."
Sargent & Lundy relied on seven years of readings from sensors that record vibrations to make their recommendation. Engineers use the readings to evaluate damage to internal parts like the drive shaft. Engineers with P.S.E.G. have said the vibrations at Hope Creek are well below the manufacturer's safety limits.
After analyzing the readings, Sargent & Lundy concluded that the vibrations were stable and the pump could continue to operate safely. According to Sargent & Lundy's report, the vibrations worsened - nearly doubling - from 2000 to 2002. But in 2002, they suddenly decreased.
Mr. Bakken said P.S.E.G.'s engineers are not certain about why the system suddenly improved. The company acknowledges that it moved the sensors used to measure vibrations at the same time the vibrations lessened. But Mr. Bakken said that did not affect the ultimate analysis that the vibrations had lessened and that the pump was safe.
In any case, Mr. Bakken said, the sensors would be constantly monitored from now on. He said an alarm system was being connected to the sensors, and if vibrations rose, the alarm would sound. Mr. Bakken said he was confident that operators would have enough time to shut down before the pump's drive shaft could break. "I will personally make sure of that before this plant is allowed to start up," he said.
The company is now making its argument to regulators. Although the state says the company should replace the bent drive shaft, the final decision will rest with the federal regulators at the N.R.C.
The commission has assigned a team to evaluate P.S.E.G.'s plan, including pump experts from N.R.C. headquarters. Although the federal regulators will not comment until the investigation is complete, meetings are scheduled with P.S.E.G. officials sometime this week.