AP: Long power outages pose risk to U.S. reactors

[dkf]

WASHINGTON >> Long before the nuclear emergency in Japan, U.S. regulators knew that a power failure lasting for days at an American nuclear plant, whatever the cause, could lead to a radioactive leak. Even so, they have only required the nation's 104 nuclear reactors to develop plans for dealing with much shorter blackouts on the assumption that power would be restored quickly.

In one nightmare simulation presented by the Nuclear Regulatory Commission in 2009, it would take less than a day for radiation to escape from a reactor at a Pennsylvania nuclear power plant after an earthquake, flood or fire knocked out all electrical power and there was no way to keep the reactors cool after backup battery power ran out. That plant, the Peach Bottom Atomic Power Station outside Lancaster, has reactors of the same older make and model as those releasing radiation at Japan's Fukushima Dai-ichi plant, which is using other means to try to cool the reactors.

And like Fukushima Dai-ichi, the Peach Bottom plant has enough battery power on site to power emergency cooling systems for eight hours. In Japan, that wasn't enough time for power to be restored. According to the International Atomic Energy Agency and the Nuclear Energy Institute trade association, three of the six reactors at the plant still can't get power to operate the emergency cooling systems. Two were shut down at the time. In the sixth, the fuel was removed completely and put in the spent fuel pool when it was shut down for maintenance at the time of the disaster. A week after the March 11 earthquake, diesel generators started supplying power to two other two reactors, Units 5 and 6, the groups said.

The risk of a blackout leading to core damage, while extremely remote, exists at all U.S. nuclear power plants, and some are more susceptible than others, according to an Associated Press investigation. While regulators say they have confidence that measures adopted in the U.S. will prevent or significantly delay a core from melting and threatening a radioactive release, the events in Japan raise questions about whether U.S. power plants are as prepared as they could and should be.

http://www.staradvertiser.com/news/breaking/Long_power_outages_pose_risk_to_US_reactors_.html

[truedelphi]

1. It was surprising to some of us that the "backup generators"

They used in Fukushima Prefecture were rather small, and could only operate for a few hours (I forget if it was six or ten or twelve hours - but WTF!)

This from an industry and major player (GE) that has billions in profits.

All of it created on top of our loved ones' dead bodies -whether it is GE propping up some dictator somewhere that we later end up declaring war on, or simply designing faulty reactors, subverting the will of the local people etc.

[RC]

7. Normally six or ten or twelve hours is plenty of time to refuel them.

What part of "Emergency" generator don't you understand?

And they were not "rather small" but rather large diesel generators. The problem was their location and the sea wall being about 3 feet short.

[Wilms]

8. You mean if to tell us if back-up is required for more than 6-12 hours it's NOT an emergency?

Then please tell us what, in Pro-Nuke-Speak, it is.

[RC]

9. Don't be so thick. I said they could be refueled.

Or is your mind so locked down and clouded from imaginary radiation that you can't see what is in front of you.

[Wilms]

10. Pardon?

My eyes are rather opened by the specter of radiation leaks these poorly thought-out systems expose the world too.

While I agree and have been citing the poor choice of location for the generators, had they survived the tsunami you'd have 6-12 hours worth of back-up electricity. Then what? It took DAYS to bring outside power to the stricken plant. It indicates that the unfolding disaster would have started 6-12 hours later than it did.
Worse, what many of us are learning is that these plants can't be simply "switched off". They require a powered cooling systems for YEARS after a safe and successful shut-down or :nuke:

Hardly reassuring.

[CreekDog]

12. Just like they were in Japan

:eyes:

[CreekDog]

11. "Normally" --well in a disaster, normal is frequently not possible

:eyes:

[truedelphi]

2. K & R. n/t

[Earth_First]

3. Also, icecubes...

Really?! Who writes this stuff?

[enough]

4. What gets me is that this has been true all along, but it was impossible to get people to focus

on nuclear power safety issues. I suppose the increased discussion of these issues is the one good thing to come out of the Fukushima nightmare.

Thanks for posting this.

[Marblehead]

5. wow

I guess we can't regulate anything

[dkf]

6. Really I am beginning to come to that conclusion.

The government only looks out for us to a certain probability, but is sadly unprepared for worst case scenarios and does not hold industry to that level either. I think this is what we can take from all the latest responses, whether it is Katrina or BP or any other disaster.

[Yo_Mama]

13. This article is flat wrong

On multiple counts, yet. This article conflates the battery backups with the backup generators. US plants have both. The battery power gives you time to set up the generators.

Btw, a bunch of big furnaces/industrial boilers have the same problem - if power goes out, you can stop the furnace but you still need to run blowers, etc for a while to dissipate heat. They have backup generators too. Admittedly they wouldn't throw much in the way of radiation, but it could be a formidable disaster if they couldn't be cooled. The smaller ones would be destroyed, but some of the bigger ones could blow.

The problem at Fukushima Daiichi wasn't that the plant didn't have the generators, it was that they were knocked out by the tsunami.

Every nuclear power plant has the same need. If you have to suddenly shut it down, you still to keep cooling it for quite a while, so you need an assured power source to do that. The type of plant doesn't matter in this issue.

Here's another article that's a little more complete.
http://online.wsj.com/article/SB10001424052748704471904576230873962812208.html

There are a number of other errors in the OP article. For example, there was a total power loss after Katrina at the one nuclear power plant down in that area. Like the current Japanese disaster, Katrina destroyed roads and power for hundreds of miles. I know it was a concern at the time:

http://www.nrc.gov/info-finder/reactor/
specific reactor page
http://www.nrc.gov/info-finder/reactor/wat3.html

This is a link about Katrina and the nuke plants affected, especially Waterford which is very close to New Orleans:
http://www.google.com/url?sa=t&source=web&cd=2&sqi=2&ved=0CB4QFjAB&url=http%3A%2F%2Fhome.engineering.iastate.edu%2F~jdm%2Fkatrina%2FData%2FElectricity%2FElectricity%2520Generation%2FNRC%2520reports%2520on%2520Waterford%2520nuclear%2520power%2520plant.doc&rct=j&q=Waterford%20nuclear%20plant%20Katrina&ei=tomSTfiPMcLUgQf00pgZ&usg=AFQjCNEzV745gMbKnZI9pGP8Dxvang-bbQ&cad=rja

So if you read this report you'll find that the plant was shut down before Katrina hit as a precaution (on the 27th) and the required cooling ran on emergency generators for more than a week. The Unusual Condition was lifted after power restoration on I think the 7th of September, and then on the 9th NRC authorized restart. But since it was down already they did some maintenance while they had the opportunity. If you look at the map you'll see why Katrina was such a big issue for Waterford. There was a huge storm surge that was expected to top the levee (and did), and it was obvious the offsite power was going to go out.

I don't know when I've seen a sillier piece of journalism. Honest to God, this is public info that anyone can find. Are they competing for some sort of "Worst Journalistic Errors" award?

Heck, even if you are adamantly against nuclear power, making such stupid errors just tends to make your case look much weaker in the eyes of the undecided. This is no slur on the original poster who had every right to think that a paper would check its facts before publishing the article.

[dkf]

14. What about this quote from the article? Has this been debunked?

"A 2003 federal analysis looking at how to estimate the risk of containment failure said that should power be knocked out by an earthquake or tornado it "would be unlikely that power will be recovered in the time frame to prevent core meltdown.""

That looks like a direct quote from the study.

[Yo_Mama]

15. Which is why they require backup power sources

I'm no expert on nuclear power plants. You'd be best advised to go straight to NRC.

But I do know that backup generators are required in most countries with nuclear plants. They are required in Germany, for example.

They probably are required in Japan too. It's not just batteries. The Peachbottom plant hasn't received rave reviews. Just having them there isn't enough. You have to constantly test and drill!

In any case, after 9/11 there were additional measures.

The modelling employed is somewhat complex. They are looking at not just loss of power but the idea that other operations modes could cause changes in operational parameters and trying to model those. Here is a 2010 report on a new model called MELCOR (lovely, eh). Not surprisingly Peachbottom has a starring role:
http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1953/sr1953.pdf

It is really easy to misunderstand these things. For example, on page 24 of the above report:

A number of simulations were run for station blackout sequences to investigate the effects of
RCP seal failures, SRV operation, and TD-AFW availability and operation on the time available
to recover ac power and re-establish core cooling. Along with the above variations in system
conditions and responses, some other factors that affect the time to core damage are the time
to battery depletion (loss of direct current (dc) power), the time to depletion of the emergency
CST tank (for cases with TD-AFW available), the system pressure, and the occurrence of
natural circulation (Case 4). Cases 4 and 6 assume infinite dc power, which mimics successful
“blind feeding” of the SGs using TD-AFW following the loss of dc (see for more
information on this topic). Meanwhile, Cases 9 and 10 assume the loss of TD-AFW at 4 hours
(which equals the station blackout coping time for Surry from NUREG-1776, “Regulatory
Effectiveness of the Station Blackout Rule,” issued August 2003) .

In the emergency operating procedures, the operators would first enter E-0, “Reactor Trip or
Safety Injection,” which would direct them to ECA-0.0, “Loss of All AC Power.” If ac power is
recovered, the operators will transition to ECA-0.1, “Loss of All AC Power Recovery without SI
Required” and/or ECA-0.2, “Loss of All AC Power Recovery with SI Required.” If ac power is
not recovered and the core-exit thermocouples rise past 1,200 degrees F (649 degrees C), the
operators will transition to SACRG-1, “Severe Accident Control Room Guideline Initial
Response.”

The Surry SPAR model does not credit operation of auxiliary feedwater following battery
depletion. Further, the SPAR model assumes core damage at the time of battery depletion
(i.e., no further opportunity for recovering ac power and averting core damage). This
assumption exists because dc power is an integral part of ac power recovery, in that it provides
the control power to operate electrical distribution system breakers in order to bring electrical
power into the power block following a station blackout. Alternate sources of dc control power
are required once batteries are depleted in a station blackout sequence, but this issue is not
further explored here.

If you see the bolded language, what that means is yes, the plants are required to have alternate sources of power, but for the purposes of this exercise they are going to pretend they don't exist.

This is very necessary. Having the backup power should work, but in the event that it doesn't, this sort of simulation allows regulators to foresee necessary mitigation steps. Failure of backup systems is an integral part of disaster and recovery planning.