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#187842 - 11/09/09 01:00 AM Re: 60 Minutes: power grid vulnerability, plus [Re: Dagny]
Art_in_FL Offline
Pooh-Bah

Registered: 09/01/07
Posts: 2432
I saw the show but was disappointed that they didn't touch on some of the underlying factors of how we got here. Simply put the move to automation and remote control of machinery has been a result of a desire to reduce labor costs, and de-unionization.

None of this was a problem in the 70s. Yes, in part because computer and networking technology didn't exist but a large factor in this is simply because power plants, generation stations and switch-yards were largely operated manually.

One of the most powerful security measures is manual control. Common sense, alertness, eyes and ears on site, are hard to remotely hack.

I'm not advocating going back to total manual control. Humans get tired, bored, lose alertness, get distracted. Automated systems are always alert 24/7. Automation has been, for the most part, beneficial. But computers don't have common sense. They are quite credulous. The strongest security is the combination of the 24/7 alertness and memory of computers with the common sense and intuitive insight of a human operator.

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#187853 - 11/09/09 05:28 AM Re: 60 Minutes: power grid vulnerability, plus [Re: Dagny]
UpstateTom Offline
Member

Registered: 10/05/09
Posts: 165
Loc: Rens. County, NY
There are a lot of reasons we have the risk we do. One is that the loads on the transmission lines are higher, so the entire grid is less resistant to damage than in years past. Another is that people connected utility computers to the Internet. Probably the same folks that decided it was a good idea to put tile over drywall in a shower.

This threat should be filed under "Yet another reason not to have war with China."


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#187858 - 11/09/09 12:21 PM Re: 60 Minutes: power grid vulnerability, plus [Re: Dagny]
Am_Fear_Liath_Mor Offline
Carpal Tunnel

Registered: 08/03/07
Posts: 3078

Then of course there is the old fashioned way of taking down the electricity grid using small quantities of C4 on each leg of an unguarded pylon on the transmission line interconnectors a few miles from all the Nuclear Generation Stations in a timed coordinated attack around the country. A Nuclear station at near maximum output (esp Pressuried Water Reactors) may have trouble coping with an instantaneous no load situation leading to a potential thermal runaway. Reacting to this type of catastrophic nuclear power station emergency such as another Chernobyl or 3 mile island with the nation without an electricity power grid would be extremely difficult especially if in the midst of a very cold winter where transportation network may be affected due to winter storms.





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#187859 - 11/09/09 12:42 PM Re: 60 Minutes: power grid vulnerability, plus [Re: Am_Fear_Liath_Mor]
James_Van_Artsdalen Offline
Addict

Registered: 09/13/07
Posts: 449
Loc: Texas
Originally Posted By: Am_Fear_Liath_Mor

may have trouble coping with an instantaneous no load situation leading to a potential thermal runaway.

A "thermal runaway" in a nuclear reactor (do you mean a power excursion?) is a problem in the reactor, not the electricity-generating part of the plant. You can't induce a power excursion via sudden "no-load" situation.

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#187861 - 11/09/09 01:40 PM Re: 60 Minutes: power grid vulnerability, plus [Re: James_Van_Artsdalen]
Am_Fear_Liath_Mor Offline
Carpal Tunnel

Registered: 08/03/07
Posts: 3078
Quote:
You can't induce a power excursion via sudden "no-load" situation.


The Chernobyl accident (power excursion) was the result of a controlled emergency shut down test, that would occur (needed in the event of a no load situation).

http://en.wikipedia.org/wiki/Chernobyl_disaster#Planning_the_test_of_the_safety_device

Although the Russian reactor did not have a containment vessel and has been criticised for being an unsafe design compared to the US designed PWR, it could be argued that a containment vessel may have resulted in the much more catastrophic ' China Syndrome ' type accident that was only barely avoided in the 3-mile island accident a few years before.



Edited by Am_Fear_Liath_Mor (11/09/09 01:42 PM)

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#187889 - 11/09/09 06:25 PM Re: 60 Minutes: power grid vulnerability, plus [Re: Am_Fear_Liath_Mor]
benjammin Offline
Rapscallion
Carpal Tunnel

Registered: 02/06/04
Posts: 4020
Loc: Anchorage AK
Au contraire, most of the power would go to an automatic shunt system to earth ground in the event the grid was lost. I think you'll find many electrical generating systems have a shunt capability and/or a phasing offset designed to neutralize the no-load flyback and over-voltage runaway.

_________________________
The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)

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#187906 - 11/09/09 08:55 PM Re: 60 Minutes: power grid vulnerability, plus [Re: Am_Fear_Liath_Mor]
James_Van_Artsdalen Offline
Addict

Registered: 09/13/07
Posts: 449
Loc: Texas
Originally Posted By: Am_Fear_Liath_Mor

The Chernobyl accident (power excursion) was the result of a controlled emergency shut down test, that would occur (needed in the event of a no load situation).

Chernobyl wasn't on their grid at the time. Nothing anyone did on their grid would have made any difference.

That accident required a lot more than loss of the water pumps for 30 seconds. Normally that alone would not have resulted in a failure.

Quote:

Although the Russian reactor did not have a containment vessel and has been criticised for being an unsafe design compared to the US designed PWR, it could be argued that a containment vessel may have resulted in the much more catastrophic ' China Syndrome ' type accident that was only barely avoided in the 3-mile island accident a few years before.

Chernobyl and TMI were completely unrelated failures, with entirely unrelated lessons to be learned. It's not only wrong but _dangerous_ to lump them together since understanding one does nothing to prevent recurrence of the other.

A western-style containment system might not have contained a power excursion on Chernobyl's scale but it would not have hurt. On the other hand, it's hard to imagine any scenario at TMI, including total core melt, where lack of containment would actually have helped.

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#187926 - 11/10/09 01:41 AM Re: 60 Minutes: power grid vulnerability, plus [Re: James_Van_Artsdalen]
James_Van_Artsdalen Offline
Addict

Registered: 09/13/07
Posts: 449
Loc: Texas
I did not see the 60-minutes report. But Wired has a followup article pointing out that the Brazilian blackout in 2007 was traced back to poorly maintained insulators on high voltage lines, and Wired provides links back to the Brazilian regulatory agency's report and formal notice on fines to the grid operator (hope your Portuguese is in good shape!)

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#187941 - 11/10/09 04:42 AM Re: 60 Minutes: power grid vulnerability, plus [Re: Am_Fear_Liath_Mor]
UpstateTom Offline
Member

Registered: 10/05/09
Posts: 165
Loc: Rens. County, NY
I think the plants would be fine if something happened to the grid. I would expect that both 9 Mile Point and Vermont Yankee both disconnected during the big northeast blackout a couple of years ago. That's the way the system is supposed to work - when in doubt, disconnect so you don't burn stuff up. Even the smallest of the cogen plants have to have gear to sense being out of sync or the grid being down and immediately disconnect.

Likewise, when we had a big ice storm up north a few years ago, it took out the transmission lines in northern NY, but the rest of the grid worked fine. The bad parts just disconnected themselves or were disconnected.

So to me it seems designed with protection and redundancy for physical problems, but not so much problems with the central control, ie computers.

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#187947 - 11/10/09 08:13 AM Re: 60 Minutes: power grid vulnerability, plus [Re: UpstateTom]
James_Van_Artsdalen Offline
Addict

Registered: 09/13/07
Posts: 449
Loc: Texas
Am_Fear_Liath_Mor is referring to Chernobyl's decision to test Plan C (diesel generators) for powering the reactor cooling pumps. There was a 30-second startup delay in the diesels and incredibly, no one had thought to see if that was a problem during the design or provisioning of the plant. So they decided to test it at a scheduled shutdown. Failure of grid power (Plan A) and the plant's normal generation gear (Plan B) is what Plan C is for.

The test failed but that didn't cause the disaster - they were already at low power. The power excursion happened when they tried to shut down the reactor. They were doomed an hour or more earlier when the control rods were nearly fully removed and no one wondered if getting minimal reactor power with the controls wide open was a warning sign...

It likely would have gone boom! if they had just shut down the reactor instead of starting the diesel generator test but not if they had been at normal operating power (maybe damaged the core, but no boom!) or if a bunch of other things had been done differently.

The bottom line is that even Soviet reactors of the Chernobyl-era could cope with loss of grid power and loss of their own normal power generation. What they couldn't cope with is being run below minimum power for hours and then suddenly shut down.

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