Public Affairs Officer
True to forecasts, New England states bore the brunt of the winter storm dubbed Nemo. With respect to nuclear power plants in the region, only one – Pilgrim, in Massachusetts – had its operations interrupted by the powerful Nor’easter.
At 9:17 p.m. Friday, three off-site power lines that provide electricity for plant safety systems were knocked out of service. In response, the reactor, as designed, automatically shut down and the facility’s emergency diesel generators activated to provide that power.
One of the criteria for a plant to declare an “Unusual Event” – the lowest of four levels of emergency classification – is the loss of off-site power for more than 15 minutes. As such, Pilgrim made that declaration at 10 p.m. Friday. The NRC issued a press release early Saturday morning.
After one of the lines was restored, the plant was able to terminate the Unusual Event as of 10:55 a.m. Sunday. But there was a setback later in the day when the 345-kilovolt line experienced new problems. Once again, the emergency diesel generators started and will supply the power needed for safety systems until the lines are fully restored.
Since the reactor was already in “cold” shutdown condition, Pilgrim did not need to again declare an Unusual Event.
NRC inspectors, and for a good part of the weekend the NRC Region I Incident Response Center, closely monitored the storm recovery efforts at Pilgrim. That will continue as repair work is carried out and plans for placing the unit back in service are developed.
Public Affairs Officer
New England states and other parts of the Northeast are battening down the hatches in anticipation of a winter storm dubbed “Nemo” by the Weather Channel.
Unlike “Finding Nemo,” the 2003 hit movie from Disney featuring a clown fish dad roaming the seas in search of his wayward son, those in the storm’s path won’t have to look far to see its impacts. Indeed, forecasts are calling for blizzard conditions and upwards of two feet of snow in the Boston area.
As with other significant storms, nuclear power plants that could be affected will be required to make preparations. These are actions such as ensuring that fuel oil tanks are adequately filled; that there are no materials on plant grounds that could become airborne missiles amid high winds; and that water-tight doors and other openings are properly closed in the event flooding becomes an issue.
NRC inspectors stationed at all operating plants on a full-time basis will likewise be busy, as they independently verify the facilities – particularly the Pilgrim plant in Massachusetts and the Seabrook plant in New Hampshire — are positioned for whatever wicked weather comes their way. To help guide those evaluations, the inspectors will follow a procedure and checklist focused on adverse weather protection.
Once the storm arrives, plant operators have plans that guide their responses. For instance, if sustained wind speeds exceed a certain level, a plant would have to shut down. Also, if flooding were to be greater than pre-determined thresholds, an emergency declaration would have to be made and a shutdown may be necessary.
During Superstorm Sandy last October, three nuclear power plants ended up shutting down for reasons that included high water intake levels and electrical grid disturbances, but all did so safely and effectively. As always, the work that takes place before the storm arrives is an essential part of ensuring any storm-related problems can be handled in a prompt, safe manner.