MONTPELIER — The state of Vermont said it wants more information about this week’s blow-out of a safety panel in the reactor building at Vermont Yankee nuclear plant, a result of three system failures.
Chris Recchia, the commissioner of the Department of Public Service, said Thursday he had written the Nuclear Regulatory Commission about the early Monday morning panel problem, saying he wanted information about whether the NRC had reviewed the systems that failed.
Recchia said he wrote to NRC Region One Administrator William Dean.
“We’re concerned,” Recchia said. “While the panel blowout is a relatively minor issue, the question is why didn’t it work?”
Vermont Yankee is currently shut down for refueling and maintenance, and the temporary hole in the reactor building, which is the secondary containment around the reactor in the event of an incident, posed no safety issues, both the NRC and Entergy Nuclear said earlier.
Recchia said that by his count three systems didn’t work as they were supposed to: an exhaust fan and exhaust louver in the reactor building both didn’t work as expected, and when the panel blew out, it flew onto the roof of the nearby turbine building.
According to design, the panel was supposed to be attached by a wire rope, and was supposed to fall back into the reactor building.
Recchia said that he asked the NRC whether the systems had been reviewed during the relicensing process conducted by the federal regulators.
“After all, this is believed to be original equipment on Vermont Yankee,” Recchia said.
“They turned on an intake fan, an exhaust fan and the exhaust louver did not open. Because of that, the pressure increased in the building and that blew out the panel. The exhaust system did not work,” he said.
“These are older systems and the plant is aging. Are these things upgraded?” Recchia said.
“I think it’s OK to use the safety word when talking to the NRC because that’s their job,” he said, a reference to Entergy Nuclear’s often evoked claim that the state was overstepping onto safety issues.
The hole left by the missing panel, estimated to be 6 feet by 10 feet, has been replaced with a temporary panel made of wood reinforced with metal, said Entergy Nuclear spokesman Robert Williams.
The panel is one of 40 panels in a band around the middle of the reactor building that are designed to “blow out” in the face of increased pressure from an oncoming tornado.
Williams said the replacement panel was made of steel reinforced pressure-treated wood, that was painted and engineered “to meet design requirements for the reactor building including safety classification, seismic capability and wind loading.”
Williams said the problem in the exhaust system had already been fixed. He said the missing panel, which is on top of the turbine building, is not considered radioactive waste even though it came from the reactor building. He said Entergy was considering returning the missing panel to its original location.
“The panel released as it was designed in response to the slight increase in pressure due to the intake fan operating and the exhaust fan initially not starting. That fan start issue has been fixed,” said Williams.
He said the 39 other panels in the reactor building had been inspected, both inside and out. “All (were) found to meet their design requirements. No issues,” he wrote in a follow-up email.
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