http://66.225.205.104/JR20120405b.mp3
Around 8 p.m. Wednesday night, the power went out at Duke's Catawba Nuclear Station on Lake Wylie, triggering an emergency response and ongoing investigation. Duke says back-up generators kicked in immediately and the public was never in any danger, but there are details of the incident that trouble regulators. A nuclear power plant needs huge amounts of outside electricity to run the systems that cool off the reactor and spent fuel. Plants have back-up generators in case the power goes out. "But as we learned at Fukushima, if you lose that backup system, there is a serious, serious problem and meltdown of the reactors could occur quite quickly because there's no ability to circulate the cooling water," says Tom Clements, a spokesman for the Alliance for Nuclear Accountability. Unlike the disaster in Japan last year, Duke's backup generators worked like they were supposed to. But Clements and federal nuclear regulators have lingering concerns. First of all, the one reactor at the Duke plant that was operating at the time of the outage shut down immediately. That's what it was supposed to do, but it also stressed the unit. But Roger Hannah of the Nuclear Regulatory Commission says it's a little like slamming on the brakes when driving 100 mph. "It is a safety feature, but you would rather it not happen very frequently because it does challenge safety systems," says Hannah. Ideally, a reactor is allowed to slowly power off - a "coastdown," it's called. The other of Duke's two nuclear units at the Catawba Station was already off for routine refueling. Duke Energy says it took about five hours to restore off-site power to the station. Now Duke and the NRC inspectors stationed at the plant are trying to figure out what happened. Losing off-site power is relatively rare - only about 10 incidents were reported to the NRC nationwide in the last year. Most often, the NRC's Roger Hannah says they're caused by severe weather. "But this was due to something in the electrical system, so it's something we have more questions about," says Hannah. "If a transmission line goes down because of a tornado, you're obviously going to lose that transmission line." In this case, Hannah says there appeared to be power coming into the station, but not getting through to the reactors. Duke Energy spokesman Tim Pettit says both reactors at the Catawba Nuclear Station will stay off for now. "We want to make sure we know exactly what caused the problem before we restart the unit, to make sure it doesn't happen again," says Pettit.