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Can Aging Nuclear Reactors Be Safe?

U.S. nuclear power plant owners are gaining regulatory approval to run aging reactors longer but, as the power plants age, the need for rigorous safety supervision steadily mounts



ISTOCKPHOTO/MICHAELUTECH

On Nov. 4, 2008, two divers were cleaning sludge and silt from an entry bay for water pumps that serve Constellation Energy Nuclear Group's Nine Mile Point nuclear power plant near Oswego, N.Y.

In the midst of the operation, the diver and the hose tender shifted their positions and the diver lost control of a plastic suction hose, leaving its trailing section in front of one of the water pipe entries. The force of the water flow, at 9,000 gallons a minute, severed a section of hose and sucked it into one of the system's pumps, fouling it. As the team tried to cope with that problem, a smaller piece of the unattended free end of the hose was pulled into a second water pump, according to an inspection report by the Nuclear Regulatory Commission.

A sudden blockage of cooling water is one of the potential nightmares that nuclear power plant operators and regulators fear most. Although these pumps did not provide cooling water directly to the reactor, they supported other essential equipment, and in this case, other pumps were working. The incident did not create a safety threat to Nine Mile Point's No. 2 reactor, the NRC concluded.

But the NRC did find "significant weaknesses" in CENG's investigation of the incident and the corrective actions it took initially. The operators on duty did not look hard enough to understand the extent and severity of the incident, nor ensure that the pumps were operational after hose intrusion, NRC inspectors later determined.

Across the U.S. nuclear energy sector, plant owners are seeking -- and gaining -- NRC approval to run first-generation plants for 20 years beyond the original license period. Nine Mile Point Unit 1's operating license has been extended to 2029, and Unit 2 is cleared to run until 2046.

The Obama administration considers the 104 U.S. reactors a cornerstone of the nation's long-term quest to reduce carbon dioxide emissions. As the plants age, the need for rigorous safety supervision steadily mounts, industry experts stress.

The pumps incident landed CENG on the NRC's carpet, leading to apologies by company executives and pledges to improve the safety culture at the plant, whose first unit started up 40 years ago. The NRC is holding open its investigation of the incident pending a further inspection.

'We had tunnel vision'

In January, in a meeting with NRC staff, CENG Nine Mile Point site Vice President Sam Belcher summed up the incident as "pretty much an embarrassment. It pointed out we had missed some things we shouldn't have missed. ... We had tunnel vision to some degree. The fact we didn't go into is why the event occurred."

CENG says it has responded with a top-down review of safety processes and a campaign to make sure its employees across the company buy into the need for an exacting attention to safety.

NRC Chairman Gregory Jaczko said in November that while improving performance measures indicate that U.S. reactors are being operated safely, the industry must guard against "distraction and complacency" in meeting safety and security goals. Slower growth in power demand, and smaller profits in the industry, make the challenge greater, he said.

"The resurgence in interest [in nuclear power] is dependent upon the sustained faith and reliability performance of the current fleet," NRC Commissioner Kristine Svinicki said last year. "The nuclear industry remains ... just one incident away from retrenchment."

The oversight of CENG's plants brought company executives and NRC staff together for a daylong performance review at Constellation's Baltimore headquarters on Jan. 19.

NRC Region I Administrator Samuel Collins said the annual meeting was not a formal inspection review but instead a more freewheeling conversation about how CENG was handling reactor safety across the three nuclear plants it operates with its new French partner, EDF. Unlike a customary inquiry into a plant issue, this meeting's focus extended to corporate accountability.

"It does not take the place of our regular oversight process," Collins explained to a reporter. "It does allow us to bring these insights back into our regulatory decisionmaking, so we can understand better why things may have happened, but more important, what's being done about it across the fleet, and whether Constellation is taking away lessons learned."

"What are their standards? How are they reinforcing those rules? Where are they focusing their time, people and money?" Collins said.

Mea culpa and red flags

The meeting was an opportunity for CENG executives to highlight the reduced radiation exposures at their plants, the company's above-average record in keeping its plants online, and its standing at the high end of the performance ratings by the Institute of Nuclear Power Operations, an industry oversight organization.

But CENG's review began with a mea culpa. "We recognize our recent performance ... does not meet expectations and we are taking aggressive fleet-wide actions," the company said.

The several incidents covered during the daylong session at Nine Mile Point and the R.E. Ginna nuclear plant near Rochester, N.Y., accounted for a small fraction of the reactors' operations during 2008 and 2009, but they raised red flags nonetheless.

At Ginna, a turbine-driven auxiliary feed water pump failed in May 26, 2009, then failed again during a test run a little over a month later. While NRC concluded it did not pose a serious safety threat to the plant, it did disable one of the backup systems that would have to remove heat from the reactor in an emergency shutdown accompanied by a loss of outside power to the plant.

The pump failed because the stem of a control valve had become corroded, and the cause of the corrosion, in turn, was leakage of steam from a system involving a connected valve. The steam leak had been going on since 2005, and the NRC said the May 2009 failure should have triggered an exhaustive search for the "root cause." Ginna operators thought they had pinpointed the issue and a fix, but they did not probe deeply enough to identify the rust issue and the steam leak that was causing it, the NRC inspectors said.

"This is a critical system. This is a high safety important system," Ginna plant Vice President John Carlin told NRC officials at the January meeting. "Our performance didn't meet expectations."

"It's caused us to challenge how we were looking at the business," Carlin added. "Do you have the right mindset?"

A progression of errors

Given the stakes involved at nuclear plants, it's not enough for operators to "fix" equipment that fails, said Glenn Dentel, NRC branch chief for the three CENG plants. They have to be certain of the cause and have proved to themselves that the equipment will do its job.

The hose incident at Nine Mile Point was a progression of errors and inadequate responses, NRC inspectors concluded. Although the underwater cleaning operation had never been done before, it was not subject to a rigorous planning process, NRC inspectors said, nor was the change in the cleaning process on Nov. 4 adequately reviewed.

Contrary to expected practice, the divers did not immediately stop work when the incident occurred. Plant management was not immediately notified. An hour passed between when the first and second pumps were fouled, the NRC said.

After pieces of the hose were removed from the intakes of the two pumps after the incident, neither pump was tested to make sure it was working properly and no other pieces of hose were stuck in the piping or pump, the NRC said. The plant's day shift operators knew that the two pumps had sucked in hose pieces, but "for unclear reasons," operators did not record the pumps as inoperable in the control room log, which would have elevated awareness of the incident, the inspectors said.

Three days later, after one pump failed to operate properly, a 5-foot hose section was removed. The next day, a 5-inch piece was found in the other pump.

In its response to the NRC about the incident last year, CENG reported to the NRC inspectors that its managers had failed to impose a "healthy skepticism" toward operators' actions during the recovery from the hose intrusion, and it listed two dozen "missed opportunities" to avoid or correct errors in handling the situation. That characterization understates the failures in the company's response, the NRC staff responded last year.

"We need to adopt a questioning attitude [and] improve the rigor of decisionmaking," Maria Korsnick, CENG's chief operating officer, told the NRC staff at the Baltimore meeting.

The regulators, sitting on one side of a long conference table, and the company officials, on the other side, share an overriding goal -- maintaining safeguards that can prevent an incident or error from triggering a nuclear reactor emergency that could jeopardize the industry's future. That risk is doubly important to CENG, which is seeking approval to build a new reactor at its Calvert Cliffs site in southern Maryland, and possibly at Nine Mile Point.

The downside of buying used nukes

"We're sharing perspectives," said Brew Barron, CENG's CEO and chief nuclear officer and an executive vice president of Constellation Energy. "The more we communicate with each other, the more effective we can be, both of us."

But at times in the meeting, each side took note of differing perspectives. CENG said new regulatory requirements from the NRC are affecting its planning and management operations. "My concern in pressing them to getting this done is what else isn't getting done," Barron said of one NRC requirement.

"We don't make the rules up," said the NRC's James Wiggins. "We waste valuable time debating individual details instead of taking a step back and saying, 'What's the best way to get this done?'" He admonished CENG not to crowd the regulators with a late response on another regulatory requirement. "Don't stick us with a five-day window to do a 10-day job," Wiggins said. "Please give us half a chance to succeed."

For most of their operating lives, the Nine Mile Point reactors were operated by Niagara Mohawk, and Ginna by Rochester Gas & Electric. Now they are part of CENG's small "fleet," along with the Calvert Cliffs reactors in southern Maryland -- three different plants with different technologies, different histories and individual workforce cultures.

Carlin, the vice president in charge of the Ginna plant, described actions to stop water leakages from a reactor refueling pit that had been a chronic problem for three decades (the leakages were contained, Barron said at the meeting). The plant's former operators apparently had decided to live with the problem, Carlin said.

"That was unacceptable," Carlin said. "That's not where our standards are.

"It was frankly the normalization of a deviation, [and] that's not how we're going to operate the facility going forward."

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500

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