UPDATED: Valve failure at nuke plant leads to special inspection

Published 6:30 am Wednesday, October 4, 2017

The Nuclear Regulatory Commission on Tuesday announced it had launched a special inspection into the failure of a high pressure coolant injection discharge valve on Unit 3 of the Browns Ferry nuclear plant.

According to a press release from the agency, the valve failed Sept. 24 during post-maintenance testing. Instead of pumping water into a storage tank, the valve “unexpectedly” pumped water into the reactor vessel. The release said it was later determined a failed nut on the valve allowed it to remain partially open.

Jim Hopson, a spokesman with the Tennessee Valley Authority, said there was no impact to the health and safety of the public and all units remain at 100 percent power. He added the plant and operators responded to the incident “as intended.”

“Browns Ferry personnel are performing detailed analyses of the valve failure in accordance with established processes and procedures,” he said.

The NRC inspection team will review the valve failure and TVA’s actions as well as maintenance practices and the history of such valves. The onsite portion of the inspection is expected to take several days.

A report documenting the results of the inspection should be issued within 45 days of the completion of the inspection.

NRC Spokesman Roger Hannah said the incident is not being viewed as a “dangerous situation.” He explained that when extra water is added to the reactor, it causes power to increase. There was a slight spike in power, he said, but he did not know when the spike was first noted.

“We’ll talk to the inspectors and look at their logs. One of the first things we do (in an inspection) is a chronology of events,” he said. “(It should) give us more information about how this valve failed.”

Previous valve failure

Browns Ferry Nuclear Plant faced nearly four years of stringent inspections after the failure of a low-pressure coolant injection valve was reported in the fall of 2010. The incident led the NRC to issue a critical “red” finding at the plant in 2011 and placement of the plant’s Unit 1 reactor in the Multiple/Repetitive Degraded Cornerstone Column.

The finding also led the NRC to implement stringent inspection standards at the plant. A 23-person inspection team spent more than 3,000 total hours reviewing a wide range of programs at the plant, including maintenance, operations, engineering, problem identification and resolution and safety culture, as well as management oversight and decision making.

The “red” finding was removed by the NRC in January 2014. The plant returned to normal oversight nine months later.