The 42-siren alarm system at the Oyster Creek Generating Station in Lacey Township was deemed unreliable for about 33 hours last week, the U.S. Nuclear Regulatory Commission said.
In the event of an emergency, the plant’s alarm system sends a radio signal to the sirens, which would then sound. Oyster Creek conducts a daily test to make sure the sirens are receiving the signals.
About noon Friday, the test showed that the sirens were not receiving the signal, NRC spokesman Neil Sheehan, said.
“They then switched to a different frequency, and at that point demonstrated that they worked,” he said. “In the meantime, they began working with the FCC (Federal Communications Commission) to look at their radio signal issue.
“They’ve identified a preliminary cause, and it has to do with a phenomenon known as tropospheric ducting. It’s a condition that impedes the sending of radio signals. It occurs primarily during the summer. Apparently the conditions were right for this to happen at Oyster Creek.”
About 9 p.m. Saturday, the NRC reported that the signals were again reliable.
The backup plan is called “route alerting,” Sheehan said.
“They will have emergency response vehicles drive three designated routes with loudspeakers and let people know there is a problem at the plant,” he said. “Of course, this is only if it’s needed.”
Personnel were at the ready during the 33-hour period, he said.
Suzanne D’Ambrosio, spokeswoman for Oyster Creek, said the sirens are now reliable and that various agencies were immediately notified.
“It was a very smooth way of identifying the potential issue and assuring that we had reliability for our sirens.
“Long term, the siren vendor is examining the sirens to see what can be done. What they did do was change the frequencies so that the sirens would work. In a long-term sort of strategy, we’re still working on that,” she said.
Sheehan said the NRC was satisfied with the way the incident was handled but that he is interested in hearing a long-term solution.
“If a real event were to happen in a plant, obviously they want to get word out as quickly as possible for people who live in the area,” he said. “And if the sirens aren’t working, that’s problematic.”
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