Regulators Question Underwater Cables At Vermont Yankee
07/01/10 5:51PM By John Dillon
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(Host) Federal inspectors have called attention to a new potential safety problem at Vermont Yankee.
The Nuclear Regulatory Commission says the plant has electric cables that are frequently submerged in water. That raises the possibility they could short-circuit and disable safety systems.
VPR's John Dillon has more:
(Dillon) The NRC flagged the issue of the electric cables in a May 10 inspection report. The document says Entergy Vermont Yankee has allowed cables that control safety systems to be continually submerged in underground trenches.
The problem is the cables are not designed to be soaked in water. The NRC said this could cause the cables to degrade and fail. The report said - quote - "this finding is more than minor because if left uncorrected, the performance deficiency has the potential to lead to a more significant safety concern."
(Blanch) "To me this is potentially one of the more serious issues that I've seen."
(Dillon) Paul Blanch is an electrical engineer with 45 years experience in the nuclear industry. Blanch is now an expert consultant for the New England Coalition, an anti-nuclear group.
(Blanch) "Failures of electrical wires or cables could result in the failure of many safety systems."
(Dillon) These safety systems include emergency generators or plant controls, says Ray Shadis, a technical advisor to the New England Coalition. Shadis says the problem is getting attention inside the nuclear industry. Recent studies by the Electric Power Research Institute - an industry group - have focused on aging electric systems in nuclear plants.
(Shadis) "They are recommending as a first step that ... nuclear industries examine each plant site to find out how many cables could possibly be affected by wetness or submergence."
(Dillon) At Vermont Yankee, technicians have drained the manholes that contained the submerged cables. Larry Smith is a plant spokesman. He said Vermont Yankee has 81 manholes with electric cables; 21 of those had water in them.
(Smith) "So we're doing periodic pumping and monitoring and Entergy has a fleet initiative to work on submerged cables. And it's called the ‘cable reliability program,' and it's going to include state of the art testing on safety related cables so we can get aggressive."
(Dillon) Ray Shadis, the coalition's technical advisor, says his organization wants to use the cable issue as argument against Yankee's request for a new 20-year operating license. He says the old cables need to be inspected, especially now that it's known that they could be weakened by exposure to water.
(Shadis) "It is our position that all safety related cables should be reviewed for aging management and that it was not done."
(Dillon) The NRC also wants Yankee to go back and examine the cables to see if they can be safely used operated underwater.For VPR News, I'm John Dillon in Montpelier.