Nuclear Plant Near Epicenter Shuts Down

NBC Washingwon ^

[matt04]

A nuclear power plant located in Louisa County, the epicenter of the earthquake in Virginia, has shut down.

The North Anna Power Station, operated by Dominion Power, has two reactors. The plant declared an "unusual event" in the wake of the 5.9 magnitude quake, which is the lowest stage on the plant's emergency scale.

As a result, the plant has been shut down.

The AP reports the plant is being run off of four emergency diesel generators, which are supplying power for critical safety equipment.

Nuclear Regulatory Commission spokesman Roger Hannah says the agency was not immediately aware of any damage at nuclear power plants in the southeast.

[wolfpat]

It’s not that big of a deal. This earthquake was way below the limit for what these plants were designed to withstand without damage.

They’ll send a bunch of “Scratch Plates” off to an engineering company to be evaluated for the exact intensity of this quake. That’ll determine if they can start back up. These scratch plates are tuned to different frequencies and set to vibrate each of the three orthogonal planes. They’ll show how strong the vibrations were at what frequency and in what direction.

[OCCASparky]

I certainly hope the reactor was built to withstand a much stronger magnitude quake than a 5.9

They are. Design basis, IIRC, is for at least a 7.0 centered within 5 miles of the plant.

[MindBender26]

A core-trip is usually automatic in cases such as this.

[OCCASparky]

Does it make anyone else nervous when there are "unusual events" at nuclear power plants? I live about 10 miles from Monticello in Minnesota.

Look at what it takes to declare an unusual event and there are lots and lots of things that have nothing to do with nuclear power that can cause that to occur. I'll be willing to bet that St. Lucie or some other southern plants will probably be declaring UE's based solely on wind come this weekend.

[OCCASparky]

Nope—North Anna is a dual-unit PWR.

[OCCASparky]

True, wolfpat. The safety system has redundant “trains”, one of which has the lion’s share of safety-related equipment running. To ensure protection of the decay heat removal and spent fuel cooling systems, only one DG need be functional.

[mad_as_he$$]

I understand. I lived in Kalifornia for many years. Saw the aftermath of all the big quakes. I have seen a great deal of damage from relatively small quakes that had more side to side motion than was anticipated. The scale measures energy released but the vertical and horizontal movement can be very different in the resulting damage. I was in a Semiconductor facility during one quake in Livermore and watched a 30,000 pound machine break all of it's anchors and literally hop across the floor. It's sister machine than was 180 degrees out the other direction never even moved or stressed than anchors.

The natural frequency components of various structures is very interesting

[justa-hairyape]

This earthquake was way below the limit for what these plants were designed to withstand without damage.

Not what I have read. The quake was right at the maximum this plant was designed for. Plant was designed for 5.9 to 6.2. This was the strongest quake recorded in that area during the modern nuclear power plant era. So there must be at least some damage. Dominion itself states that these plants are built to the local requirements. And they have plants scattered around the east and mid-west.

[DKM]

Each unit has two redundant safety trains, i.e. duplicate of everything they need to either shut the plant down safely and/or maintain core temperature. Each safety train has one generator, which by design, is all they need to maintain that unit. Running both trains at the outset of an emergency is likely standard EOP. Loss of one genset does not mean they have inadequate generating capacity. Additionally, they most likey can cross-tie emergency electrical busses across both units, resulting in the availability of 3 gensets, where only two are needed by design for both units. Essentially, they are still up one genset, instead of down one as you imply. 22 years in Nuclear Generation.

[wolfpat]

6.2 is the “Safe Shutdown Earthquake”.

The “Design basis Earthquake” is probably around 7 point something. I’ve been out of the industry for 6 years, and I forget the exact numbers.

No, there doesn’t “have to be some damage”.

[DKM]

Wolfpat - exactly. Left the business in 2002 after 22 years.

[wolfpat]

I was fired in 2004, after 24 in the business.

[wolfpat]

I just realized I’ve been out for 7 years. My how time flies.

[sefarkas]

The U.S. Nuclear Regulatory Commission headquarters in Rockville, Md., is monitoring an Alert at the North Anna nuclear power plant in Virginia, following today’s earthquake in central Virginia. The NRC is also monitoring Unusual Events, the lowest emergency classification, declared at several other Eastern U.S. nuclear power plants. In accordance with agency procedures, the NRC’s regional offices in King of Prussia, Pa., and Atlanta have activated their incident response centers. NRC resident inspectors at the affected nuclear power plants will continue to monitor conditions for the duration of the event. North Anna declared its Alert, the second-lowest of the NRC’s four emergency classifications, when the plant lost electricity from the grid following the quake just before 2 p.m. Tuesday. Power is being provided by onsite diesel generators and the plant’s safety systems are operating normally. Plant personnel and NRC resident inspectors are continuing to examine plant conditions. NRC staff in the Maryland headquarters felt the quake and immediately began checking with U.S. nuclear power plants. The NRC is in direct communications with North Anna and is coordinating its response with other federal agencies. Nuclear power plants are built to withstand environmental hazards, including earthquakes. Even those plants that are located outside of areas with extensive seismic activity are designed for safety in the event of such a natural disaster. The NRC requires that safety significant structures, systems, and components be designed to take into account the most severe natural phenomena historically reported for the site and surrounding area. Plants declaring Unusual Events, which indicate a potential decrease in plant safety, include Peach Bottom, Three Mile Island, Susquehanna and Limerick in Pennsylvania; Salem, Hope Creek and Oyster Creek in New Jersey, Calvert Cliffs in Maryland, Surry in Virginia, Shearon Harris in North Carolina and D.C. Cook and Palisades in Michigan. All these plants continue to operate while plant personnel examine their sites.

ref: http://www.nrc.gov/reading-rm/doc-collections/news/2011/11-153.pdf

[null and void]

*groan*

[sefarkas]

Dominion Virginia Power shut down its two North Anna reactors as a result of the earthquake, according to the the company.

The earthquake was felt at the North Anna Power Station and the reactor operators, following procedures, shut down the reactors," said company spokesman Jim Norvelle. "It was a manual shutdown."

The plant declared an alert, the second lowest level of emergency declaration, a commission spokesman said.

About what you’d expect. Virginia was at the epicenter of the quake.

Dominion Virginia Power's Surry Power Station is operating as normal, he said.

Also about right. Power was knocked out at North Anna – it has diesel generators to keep things running - but retained at Surrey.

How about Limerick in Pennsylvania?

“The earthquake was felt, but it didn’t jeopardize the safe operation of the plant. Both units are 100 percent and are online,” Szafran said in a phone interview just before 3 p.m. Tuesday.

“For this type of event, we have procedures in place, including a walk-down of all structures.” No evacuation was necessary, he said.

Indian Point in New York?

Indian Point Nuclear Power Plants have begun “Abnormal Operating Procedures,” according to Entergy Spokesman Jim Steets, after Tuesday afternoon's 5.9 magnitude earthquake. Abnormal Operating Procedures, or AOP, mean that the plant is being inspected for damage, although none has yet been found.

Calvert Cliffs in Maryland?

The Calvert Cliffs Nuclear Power Plant in Maryland, the closest nuclear plant to Washington, D.C., remained stable at 100% of capacity, a spokesman for Constellation Energy Nuclear Group LLC said Tuesday.

Constellation declared an "unusual event" at the plant, said Constellation spokesman Mark Sullivan.

This story mentions two more.

Mr. Sullivan said the company's nuclear plants in Scriba, N.Y., and Ontario, N.Y., were performing similar examinations although neither plant registered abnormal seismic activity.

These would be Nine Mile Point and R.E. Ginna.

Now, of course, we understand that Fukushima Daiichi in Japan was hit by an earthquake, though it may turn out that it was the tsunami following the earthquake that was the determinative event. No American plant is vulnerable to tsunami and this wasn’t the kind of earthquake that could generate a tsunami.

Regardless of all this, it makes sense that the very fact of an earthquake set reporters to asking about the local nuclear facilities. By and large, reporters have been responsible, calling over to the plants – when the lines were open – and finding out what’s what.

And what’s what? The plant nearest the epicenter closed down – though mostly due to loss of external power - and most of the others (all of the others I found information about) are puttering right along, checking around the plants for any damage but mostly unaffected.



ref: http://neinuclearnotes.blogspot.com/

[sefarkas]

Actually it is not sensible.

The power grid is a superior source of reliable electric power in comparison to on-site sources. The power grid has any number of generators as well as switching equipment to maintain power to the loads. A single nuclear plant running at full power will only draw about 50MWe from the power grid, mostly to run pumps. The load is less at shutdown. The power-grids can easily handle a single nuclear site electric power load. Most nuclear plants have two circuits coming into the station and one going out (for each reactor/turbine pair). The three circuits are fairly independent. A nuclear power plant pushing 800MWe to 1200MWe out to the power grid has to be connected to that power grid -- you cannot sit and spin a turbine at full power with no load, or even partial power for that matter. The circuits coming in from off-site are connected to the same AC bus that the on-site DG is connected to, so that if the off-site circuit trips, the DG picks up that load. Two safety-systems in the nuclear plant; thus, two DGs. Either safety-system is sufficient. Safety-systems are meant to be independent to avoid common-cause failures, so cross-connecting is physically possible, but rarely done.

[justa-hairyape]

That is about what you would expect for a 5.8-5.9 . Only the reactors close to the epicenter would experience significant damage. North Anna lost external power due to damage from the earthquake. Unless of course someone just panicked and turned a switch off during the quake :>

[justa-hairyape]

This website linked below is a little bit on the fringe, but they have put together some interesting points in their article. Just posting it for discussion purpose.

Media Silent On Fate Of North Anna Nuclear Plant At Epicenter Of 5.9 Mineral Virginia Earthquake

[Domestic Church]

You link was blocked for phishing when I clicked.