Power Reactor Event Number: 47201
Facility: NORTH ANNA
Region: 2 State: VA

Event Date: 08/26/2011
Event Time: 13:00 [EDT]

Event Text
UNANALYZED CONDITION BASED ON SEISMIC ACTIVITY THAT POTENTIALLY EXCEEDED DESIGN BASIS EARTHQUAKE MAGNITUDE

On August 23, 2011 at 1351 hours, North Anna Power Station experienced a seismic activity event which resulted in a loss of offsite power and automatic reactor trip of both units. At 1403 hours, an Alert was declared. based on Shift Manager judgment, due to significant seismic activity on the site. Subsequent to the earthquake, both units were stabilized and offsite power was restored. Following the event, seismic data was retrieved from the installed monitoring system and shipped to the vendor to determine the response spectrum for the event. On August 26, 2011 at 1340 hours, initial reviews of the data determined that the seismic activity potentially exceeded the Design Basis Earthquake magnitude value above 5 Hz. Therefore, this is reportable per 10CFR50.72(b)(3)(ii) (B) for the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety.

North Anna Unit 1 is currently in Cold Shutdown with the Residual Heat Removal System providing core cooling. North Anna Unit 2 is currently in Hot Shutdown and will be taken to Cold Shutdown with the Residual Heat Removal System providing core cooling. No significant equipment damage to Safety Related system (including Class 1 Structures) has been identified through site walk-downs nor has equipment degradation been detected through plant performance and surveillance testing following the earthquake. Therefore, there is reasonable assurance that the Safety Related systems are fully functional.


Funny thing is the NRC deleted this report, google will still find the event number and first sentence of the text, but not even google cache will bring up the report now.

google brings up this:
NRC: Current Event Notification Report for August 29, 2011
www.nrc.gov › ... › Event Notification Reports › 2011 - CachedSimilar
Jump to 47201‎: Power Reactor, Event Number: 47201. Facility: NORTH ANNA Region: 2 State: VA Unit: [1] [2] [ ] RX Type: [1] W-3-LP,[2] W-3-LP ...

http://www.google.com/#hl=e...10e&biw=1024&bih=454

uhm yea, plants fine, there are other threads about it, they shut ti down after the quake for a safety inspection, afaik its back online now.

quote Originally posted by hookdonspeed: uhm yea, plants fine, there are other threads about it, they shut ti down after the quake for a safety inspection, afaik its back online now.

That was an NRC report, it trumps any other article. However it was also a preliminary and suggested may be, it doesn't state there is any damage, just there is the possibility of such. I only found it interesting the NRC removed the article from the public section, and posted evidence that they did. I suspect it was to keep from alarming the public on a maybe, but that raises the question, why did they post it at all?

quote Originally posted by dennis_6: That was an NRC report, it trumps any other article. However it was also a preliminary and suggested may be, it doesn't state there is any damage, just there is the possibility of such. I only found it interesting the NRC removed the article from the public section, and posted evidence that they did. I suspect it was to keep from alarming the public on a maybe, but that raises the question, why did they post it at all?

it was covered in several news sources that 2 of the 5 most vulnarable plants were within range of that quake, VA and PA

quote Originally posted by hookdonspeed: it was covered in several news sources that 2 of the 5 most vulnarable plants were within range of that quake, VA and PA

NRC is a federal agency, not local media. The report stated the frequency was above what the plant was designed for, not the strength of the quake. Think of a device that was being fed 120 volts as it should be, but the frequency was 200hz instead of 60hz. Damage to the device would be possible, even though the voltage (magnitude) was within spec. The frequency was beyond what the device was designed for.

[This message has been edited by dennis_6 (edited 08-30-2011).]

Nuclear Panel Expanding Team to Check for Quake Damage
By MATTHEW L. WALD
Published: August 29, 2011

WASHINGTON — The earthquake last Tuesday in Virginia may have produced stronger shaking at the North Anna nuclear plant than the reactors were designed to withstand, and the Nuclear Regulatory Commission has sent additional inspectors to determine what steps are needed to determine if there is damage. No significant damage has been identified so far.

Both reactors shut down automatically because the earthquake, which was centered about 10 miles away, disrupted access to off-site power supplies. Both are now in “cold shutdown,” which means that their fuel is no longer producing much heat and the cooling water temperature is below 212 degrees.

The plant owner, Dominion, reported to the Nuclear Regulatory Commission on Friday that the plant was in an “unanalyzed condition” because preliminary laboratory analysis of a mechanical sensor called a scratch plate showed that the ground motion “potentially exceeded” the level for which the plant was designed.

Nuclear reactors are designed to withstand earthquake energy as measured by ground motion, a technique that takes into account the plant’s distance from the epicenter. Dominion said it was holding off on saying what the ground motion was until analysis of the instruments was complete.

James W. Norvelle, a Dominion spokesman, said an initial “walkdown” had found some thermal insulation shaken off pipes carrying steam or hot water and damage to some electrical conductors on top of a transformer, but no other damage. Plant personnel are now a quarter of the way through a detailed inspection of plant systems, and a third of the way through inspection of walls, floors and other structures, and have yet to find damage. Initial walkdowns were done immediately after the earthquake and found nothing.

“We still have found nothing,” Mr. Norvelle said.

But an office building at the site, built to commercial, nonnuclear standards, had cracks in the foundation, he said.

Cases of reactors experiencing bigger ground motions than the designers had anticipated are rare, industry experts said.

The commission announced Monday that it was sending an “augmented inspection team,” which is expected to be on site for several weeks. Sending the team “should not be interpreted to mean that Dominion staff responded inappropriately or that the station is less safe as a result of the quake,” said Victor McCree, the commission’s administrator for the region that includes Virginia.
A version of this article appeared in print on August 30, 2011, on page A12 of the New York edition with the headline: Nuclear Panel Expanding Team To Check for Quake Damage.
http://www.nytimes.com/2011.../us/30nuke.html?_r=1

---------------------------------------------------------------------------------------------------------------------
The normalcy bias, or normality bias, refers to a mental state people enter when facing a disaster. It causes people to underestimate both the possibility of a disaster occurring and its possible effects. This often results in situations where people fail to adequately prepare for a disaster, and on a larger scale, the failure of the government to include the populace in its disaster preparations. The assumption that is made in the case of the normalcy bias is that since a disaster never has occurred then it never will occur. It also results in the inability of people to cope with a disaster once it occurs. People with a normalcy bias have difficulties reacting to something they have not experienced before.[citation needed] People also tend to interpret warnings in the most optimistic way possible, seizing on any ambiguities to infer a less serious situation.
http://en.wikipedia.org/wiki/Normalcy_bias

[This message has been edited by dennis_6 (edited 08-31-2011).]

Spent nuclear fuel shifted
Inspectors find that containers holding spent fuel shifted several inches in last week's earthquake.
Date published: 9/1/2011

By RUSTY DENNEN

In another indication of the power of last week's magnitude-5.8 earthquake, officials at North Anna Power Station said yesterday that 25 of 27 vertical steel casks that hold highly radioactive spent fuel shifted on their pads.

Richard Zuercher, spokesman for Dominion power's nuclear operations, said none is leaking, all are intact, and there is no danger to the public or plant employees.

"The earthquake did move, slightly, some of the dry storage casks on the pad," he said. The steel casks, which weigh up to 115 tons when loaded, shifted between an inch and 4 inches.

"We're evaluating whether we need to move them back," Zuercher said.

Other newer steel and concrete casks that sit horizontally on pads sustained some minor "cosmetic" damage, Zuercher said. "Everything there is intact and easily fixable." Thirteen of those casks also contain spent fuel.

The fuel for North Anna's two reactors is enriched uranium dioxide, compressed into small ceramic pellets and stacked in metal-alloy tubes called fuel rods.

The rods are bundled together in 8-inch by 14-foot fuel assemblies. There are 157 fuel assemblies in each reactor.

After powering each reactor for about nine months, the fuel is spent, then shifted into a swimming-pool-like container to cool underwater for several years.

When cool enough, the fuel assemblies are shifted to the casks and stored outside the reactor containment domes on pads in a secure area. Each cask contains 32 fuel assemblies.

Plans for a permanent, national repository for the fuel, which remains radioactive for thousands of years, are still in a holding pattern. So the material is accumulating at the nation's 104 commercial nuclear reactors.

Environmental groups argue that spent-fuel pool and storage casks are inviting targets for terrorists; the industry maintains both are safe and secure.

The topic has come up in recent years at North Anna because Dominion has an application pending with the NRC for a third reactor. The plant is on Lake Anna in Louisa County, near Mineral.

The news about the fuel-storage casks comes as a special Nuclear Regulatory Commission team continues its work at North Anna. The team arrived earlier this week to look into reports that ground motion from the quake may have exceeded the plant's design.
Spent nuclear fuel shifted page 2
Inspectors find that containers holding spent fuel shifted several inches in last week's earthquake.
Date published: 9/1/2011

continued

That vibration led to a loss of offsite power, triggered an automatic shutdown of the two reactors and damaged some bushings on the main transformers, along with some pipe insulation. Some minor damage to support buildings was also reported.

The plant's engineers and the NRC inspectors "are basically inspecting everything," Zuercher said, including all structures, pipe supports and hangers, and all system components, including pipes, valves and electrical components.

He said about 40 percent of the inspections have been completed on Unit 1, 29 percent on Unit 2. Both reactors remain shut down, and will remain that way until the inspections and analysis are complete.

He said that 44 percent of inspections of buildings at the plant are done.

"To date, there's no significant damage to any safety-related equipment" or systems for shutdown and cooling the reactors.

Zuercher said the NRC team, which includes seismic and technical experts, is expected to be at North Anna through the end of the week. Then they will look at their findings and return for a follow-up visit. At some point, they will hold a public meeting on what they found.

Meanwhile, North Anna is awaiting an analysis of 36 "scratch plates" that recorded the ground motion at Unit 1. A diamond stylus etched a record of the shaking on each metal plate. That data, which will tell whether the plant exceeded its design for what's known technically as "ground acceleration," could be available tomorrow.

Rusty Dennen: 540/374-5431
Email: rdennen@freelancestar.com
http://fredericksburg.com/N...18/index_html?page=1

Besides the possibility of the "bowling pin" effect of one toppling and causing MANY more to topple, what might be the result? I understand the casks are virtually indestructible.