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.