The federal Nuclear Regulatory Commission is keeping a close eye on the PPL Susquehanna Steam plant in Salem Twp. near Berwick after the second automatic shutdown of a reactor within a week.
The two incidents are the most recent in a series involving Unit 2, which has had other problems this year, including a computer malfunction and hydraulic oil leak in November and a water leak in June.
Unit 2 shut down automatically early Sunday during routine testing of a valve on its main turbine system.
While restarting the unit Wednesday night and preparing to go into operational mode, there was a problem with one of the water pumps, PPL Susquehanna Spokesman Joe Scopelliti said.
The water level in the reactor core went down to 13 feet instead of the normal 15. But there was still plenty of water above the core and there was never any danger to the public, he said.
"It's all relative to how you think about it. The water level was down, but there was no emergency and no safety issue," Mr. Scopelliti said.
The reactors at the plant contain nuclear fuel rods. Water is pumped from a vessel through these reactors. Splitting the atoms boils the water and converts it to steam, which is pumped through turbines with hundreds of rotating blades that spin to create electricity. Water that is not converted to steam is cooled down and pumped back into the vessel. The water comes from the Susquehanna River.
Neil Sheehan, a Nuclear Regulatory Commission spokesman, said the agency has questions about the two incidents at the PPL plant.
"We are always on the lookout for trends, patterns in terms of overall plant performance, and this certainly would fall into that category," he said. The commission "will see if they are representative of any larger issues at the plant," he said.
Mr. Sheehan said the NRC expects the company will not restart Unit 2 until it fully understands what the problem is and takes corrective action, such as repairing the pump.
"We will continue to monitor this through our two resident inspectors assigned to Susquehanna," he said.
Mr. Scopelliti confirmed Unit 2 will remain down until the cause of Wednesday's shutdown is investigated.
Eric Epstein, chairman of the nuclear watchdog group Three Mile Island Alert, has a chronology of incidents at the Susquehanna plant dating back to 1982. He calls the latest shutdowns a "troubling" trend.
"We need to be careful. If some of these plants are not operating as they should, we need to do triage. We need to correct it," Mr. Epstein said. "This is troubling, because nuclear power plants are not supposed to shut down this frequently."
He said historically, Unit 1 has been the underperforming reactor, but now it seems Unit 2 has that distinction.
It's standard procedure for the NRC to increase oversight on a nuclear plant that has three or more automatic shutdowns within 7,000 hours of operation, Mr. Epstein said.
PPL Susquehanna was subject to additional oversight after Unit 1 was shut down July 16, 2010, when nearly 1 million gallons of water from the Susquehanna River flooded the basement of the turbine building.
Mr. Sheehan said PPL took steps to resolve the issue and the commission closed out the inspection finding.
"At this point, they are back in what we would say is normal oversight with the NRC, which still involves thousands of hours of inspections each year," he said.
However, the commission has questions pertaining to the two shutdowns this week, and will expect a response from PPL as to why they had those issues, Mr. Sheehan said.
Mr. Scopelliti admitted there have been quite a few shutdowns in both units during the past two years, but said a lot of them had to do with routine testing.
"That's the bottom line. The plant's got to operate safely," he said. "And if it can't operate safely, shut the plant down and fix the problem."
Contact the writer: eskrapits@citizensvoice.com Recent plant issues
-âOct. 5: PPL reduced power to both units as a precautionary measure because the data monitoring units showed conditions could cause turbine cracking.
-âOct. 20: PPL shuts Unit 1 down for inspection.
-âNov. 7: Unit 1 started back up; PPL found cracking in small number of turbine blades and is planning replacement in 2013.
-âNov. 9: Computer malfunction causes shutdown of Unit 2.
-âNov. 19: Hydraulic oil leak causes Unit 2 to be shut down again after it was restarted when the computer glitch was fixed.
-âDec. 16: Unit 2 unexpectedly shuts down during routine testing of valve in main turbine system.
-âDec. 19: Unit 2 shuts down again due to low reactor vessel water level as it was being prepared to start back up.