Hurricane Irene lingered in the Mid-Atlantic Saturday like a dinner guest who wouldn’t leave, soaking the region with rain and pounding it with wind. Throughout the storm, the NRC has kept watch over the nuclear power plants in her path.
Initial reports show that only one nuclear plant in the Mid-Atlantic experienced any issues as Irene passed. Unit 1 of the two-reactor Calvert Cliffs plant in Lusby, Md., shut down automatically late Saturday evening after heavy wind ripped some siding off a building. The siding struck a transformer, knocking it offline, and that caused a turbine to trip, which in turn triggered the reactor shutdown.
As of Sunday morning, the reactor was safe, there was no release of radioactivity, and NRC inspectors onsite were helping plant personnel inspect and secure the facility. Unit 1 terminated its “unusual event” declaration early Sunday morning. Unit 2 remains operating at 100 percent power.
As Irene moved up the coast, the Oyster Creek plant in Toms River, N.J., which was directly in the projected storm path, shut down in anticipation of experiencing hurricane-force winds. Millstone, further north in Connecticut, reduced power in anticipation that it might also have to shut down. These precautionary moves demonstrate the focus of the NRC and industry on maintaining the safety of nuclear power plants in extreme circumstances such as hurricanes.
None of the plants in areas hit by the storm on Saturday lost offsite power from the grid. However, several plants reported some of their emergency sirens were knocked offline by power outages. All plants have back-up options for such a situation.
The NRC’s Office of Public Affairs handled numerous media inquiries about the status of the plants. The BBC World News even cited Fukushima as evidence of what a natural disaster can do to nuclear power plants. There were of course two huge differences between the double whammy that hit Japan and Hurricane Irene. First, none of the projected wind speeds or storm surges even came close to threatening the levels that the nuclear power plants in Irene’s path were designed to withstand. And, of course, we could see Irene coming – there was time to prepare and send additional NRC inspectors to the plants before the storm hit.
Other questions focused understandably on when Calvert Cliffs 1 and Oyster Creek will be able to resume operations. Unfortunately, it’s easier to shut down a nuclear power plant than it is to start one up again. There are protocols the plants must follow to ensure that everything is ready to operate again. We’ll have more about what plants must do before restarting in a future blog post.
David McIntyre Office of Public Affairs Moderator: This post has been slightly revised from the original.
U.S. NRC Blog 
We get our power from North Anna. The feed goes right by the town of West Point. Politicians were very quiet on this one! We don’t need to know.
Nuclear plants typically operate at 100 percent power and are not ramped up and down each day to meet time-of-day electrical demand. Nuclear plants have tight limits on how fast they can heatup and cool down the reactor vessel during startups/cooldowns to avoid large thermal stresses on the metal. While a hydro plant can go from 0 to100 percent quite rapidly, a gas turbine or a large diesel generator takes slightly longer, and very rapid startups cause premature wear of these machines (e.g., like starting your car on a cold day, then flooring the accelerator). Coal plants do take a while to restart and reach full power since they run on a steam cycle and must heatup a lot of water, as well as avoid overstressing their boiler tubes.
Grid operators take a number of steps to manage the sudden loss of a large electrical unit. Some of the ways they do it is by having plants online providing a so-called “spinning reserve” (they are running, but at a reduced power level so they can ramp up quickly). Other plants such as hydro units can also ramp up quickly as you mentioned. Since electrical systems are interconnected via large transmission lines, they can also pull in power from neighboring systems if necessary.
Nuclear power plants have procedures that they follow when starting up a plant. How long it takes to restart depends on what caused the shutdown in the first place.
In the case of Calvert Cliffs, which tripped offline Saturday night when a piece of siding struck a transformer, causing a turbine trip, which in turn caused a reactor trip, workers needed to assess the condition of equipment, make repairs and complete tests before returning to power. At Oyster Creek, where operators conducted a controlled shutdown as a precaution, the plant began the process of restarting not long after Hurricane Irene made its way past the Jersey Shore. There was no equipment damage, so the plant was able to restart sooner.
As you point out, the loss of electricity in areas affected by Hurricane Irene was unrelated to the nuclear plants that shut down as a precaution. We’ve revised the post.
What are the typical costs associated with the shutdowns? How much electricity is cut off to the public? Where does the alternative power come from during the shutdowns?
Thanks Jay
@David – While your report is mostly factual and reassuring, I have a real problem with your phrasing in the following paragraph:
“Other questions focused understandably on when Calvert Cliffs 1 and Oyster Creek will be able to resume operations. Irene has left millions of people without electricity, and everyone wants to know when their air conditioners, refrigerators and televisions will be working again. Unfortunately, it’s easier to shut down a nuclear power plant than it is to start one up again. There are protocols the plants must follow to ensure that everything is ready to operate again, including their emergency sirens. We’ll have more about what plants must do before restarting in a future blog post.”
There is NO relationship between the people who are without power and the decision to preemptively shut down the nuclear plants. The lack of power at residences and businesses is due to open circuits caused by downed delivery systems, not by a lack of sufficient power generation.
It is misleading and irresponsible to imply otherwise.
IF it was the case that a preemptive shutdown of a nuclear plant in anticipation of high winds that never arrived DID cause people to be without power until the plant started back up, that would be a significant public safety issue that the NRC would have address. As a former submarine engineer officer who operated nuclear plants that reliably supplied vital, life-sustaining power, I know that there is no technical reason why it takes several days to restart a plant that is shut down on purpose and needs no lengthy investigation of the cause of shutdown.
The xenon transient might insert a modest delay depending on the time in the fuel cycle, but otherwise the plant should be good to go and back on the line within hours. If that is not the case, there is something dreadfully wrong with our regulatory system.
How long does it take to restart a nuclear plant and why so long? Is it hard to get it “heated up” again becaues they are so large? I know a hydro or gas plant can be started right away but doesn’t a coal plant take a long time too? Also, what happens when a nuclear plant goes “off line” suddenly the system loses 1000 megawatts but I don’t know of a blackout that happens from that. How do you cope with that?
Thank you so much for this interesting update. As a member of the Sandwich Generation, caring for elderly parents and babysitting grandchildren, my “duties” led me to the East Coast for three years. We have since moved again towards the west, but have several friends and relatives that were impacted by Hurricane Irene and one of our concerns were these power plants. What great news to hear that all is well. And how interesting to learn part of the reason for the delay in getting the power back up. I appreciate this very much.
“Nuclear Plants Safely Weather Hurricane Irene”
As if there was any doubt??
Says something when the media BELIEVES windmill advocates saying windmills can “naturally” take hurricanes better than nuclear plants! Where o where are the nuclear proponents in the media when you need them??
James Greenidge