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PostPosted: Mar 13, 2011 7:23 pm 
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Obsolete or not, I'd think a simple 19th-century steam engine (minus the boiler) directly connected to the cooling pumps via a clutch, as a redundancy in the emergency cooling system, would've been an improvement over waiting for someone to show up with another diesel generator.

They run on steam (obviously), they always work, they're almost bullet-proof, and even 19th-century farmers could maintain and operate them. There are thousands of designs with decades of service history in extreme environments, including ships and locomotives.

I assume nobody ever tried such a crazy thing because it would've been such a jarring disconnect to see the scientific advancements of the atomic age hooked to a clunky steam engine from their grandfather's era.

But you wouldn't have to worry about diesel fuel contamination, diesel fuel quantity, fuel filters, oil filters, fuel injectors, glow plugs, the diesel starter motor, starter batteries, the water level in the starter batteries, the generator set, breakers, pump motor controller electronics, and a pump motor.

All you'd have is a pressure gage, a manual valve, and a throttle lever, all of which could be operated remotely with just mechanical linkages.

Of course with passive cooling you eliminate the whole system.


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PostPosted: Mar 13, 2011 7:40 pm 
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gturner6ppc wrote:


They run on steam (obviously), they always work, they're almost bullet-proof, and even 19th-century farmers could maintain and operate them.


But where would you get the steam from?

Now there's a thought - steam was vented at hight pressure from a containment building.

Or could you use some Spent Nuclear Fuel, housed in a small Richter-9.5 proof building, as a steam generator?


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PostPosted: Mar 13, 2011 8:27 pm 
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Guys,

I have lot's of unanswered questions that, no doubt, will be answered in the days and weeks ahead. Right now, my thoughts an prayers go out for the people of Japan and for the brave operating crews of all the NPPs who stayed on station to deal with the aftermath. I'm sure we'll hear some heroic stories about it..

Now, about the generators etc...

I'm not personally familiar with the practice in Japan, but it's common over hear to have dedicated diesel-driven "fire pumps" that can be plumbed into a variety of water delivery systems at the plant. We haven't heard much about that. It's also common over here to have accident mitigation strategies that include the use of fire pumper trucks to deliver water (the later particularly to replenish SFP water. I haven't heard anything about that. Finally, it's not unheard of for plants to have spare diesel generators "staged" at remote locations for rapid delivery in the event of a really serious problem (like a hurricane). The Japanese have an outstanding plant operations culture, so I'll bet all of these and other mitigation strategies were in place. There will be lot's of lessons to learn, I'm sure, after the present crisis is dealt with.


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PostPosted: Mar 13, 2011 11:22 pm 
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alexterrell wrote:
gturner6ppc wrote:


They run on steam (obviously), they always work, they're almost bullet-proof, and even 19th-century farmers could maintain and operate them.


But where would you get the steam from?

Now there's a thought - steam was vented at hight pressure from a containment building.

Or could you use some Spent Nuclear Fuel, housed in a small Richter-9.5 proof building, as a steam generator?


If your reactor is hot and you have water, you have steam. Not enough to run the power turbines, but plenty to run a 5,000 HP steam engine. :)

There are quite a few advantages of such a cheesy engine over a diesel generator.

No critical electrical components.
No extra heat generation that requires external cooling (no diesel radiator).
No exhaust gases such as carbon monoxide, and no particular cooling requirements, so it could be run inside the secondary containment.
No combustible fuel, no combustion,and no hot spots, so it won't be an ignition source.

Sherrell, I'm thinking the flaw in a plan relying on external diesels, diesels at a back-up site, or fire trucks is that a tsunami takes them all out at once and renders road transport virtually impossible, forcing the operators to use only what's on hand in the plant. Putting the diesels in their own concrete vault, located well above potential flood levels, probably would've prevented this issue from arising.


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PostPosted: Mar 14, 2011 12:06 am 
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Location: Idaho Falls, Idaho
Fire systems at the INL have a combination of electric and diesel driven fire pumps( 1500 gals/min). They also have tanks of fire water and potable water storage on the order of 750,000 to 1 million gallons (depending on the campus).

Now we have had times due to maintenance fowl ups where the underground has broken. It takes a very short time to drain the tank when the underground mains break. Once the tank gets dry and you have no electric power to pump it out of the ground then your done. The diesel pump will run as long as there is fuel or it dies.

If their underground mains are broken then they might have routed past breaks with fire hose or pipes on top of the ground. But it seems they could not do this for unit number 1 and had to route seawater there.


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PostPosted: Mar 14, 2011 12:22 am 
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Joined: May 15, 2009 3:29 pm
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There is an unusually expert attack on nuclear safety in relation to the Japanese problems here:
http://www.theoildrum.com/node/7638

'The subject of Nicole's master thesis at Warwick University was nuclear safety. Subsequently at Oxford Institute for Energy Studies, her research field was power systems, with a specific focus on nuclear safety in Eastern Europe.'

Perhaps some of the commentators here would offer critique and rebuttal.

At least she is upfront about her opposition to nuclear power.


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PostPosted: Mar 14, 2011 12:31 am 
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gturner6ppc wrote:
If your reactor is hot and you have water, you have steam. Not enough to run the power turbines, but plenty to run a 5,000 HP steam engine. :)

There are quite a few advantages of such a cheesy engine over a diesel generator.

No critical electrical components.
No extra heat generation that requires external cooling (no diesel radiator).
No exhaust gases such as carbon monoxide, and no particular cooling requirements, so it could be run inside the secondary containment.
No combustible fuel, no combustion,and no hot spots, so it won't be an ignition source.

Sherrell, I'm thinking the flaw in a plan relying on external diesels, diesels at a back-up site, or fire trucks is that a tsunami takes them all out at once and renders road transport virtually impossible, forcing the operators to use only what's on hand in the plant. Putting the diesels in their own concrete vault, located well above potential flood levels, probably would've prevented this issue from arising.


I like this idea. Turn decay heat into the solution to the problem of decay heat.
I think a radiator of some kind would still be needed. Condensing the radioactive steam and returning it to the reactor is obviously preferable to venting it. Venting could still be an option if the radiator fails.

Another option might be a set of small rankine cycle generators dedicated to internal loads. They could be running during normal operation and would keep operating even if the reactor was shut down and/or connection to the grid was lost.


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PostPosted: Mar 14, 2011 2:52 am 
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gturner6ppc wrote:
Obsolete or not, I'd think a simple 19th-century steam engine (minus the boiler) directly connected to the cooling pumps via a clutch, as a redundancy in the emergency cooling system, would've been an improvement over waiting for someone to show up with another diesel generator.


Believe it or not, BWRs actually have steam driven coolant injection pumps. They still need electric power to operate the valves, but batteries are enough for that, the diesels aren't needed. This system is what cooled Fukushima 1 for the first 8 hours after the tsunami hit, then the batteries ran dry. I wonder what they do with the steam, though. It's probably condensed in the suppression system (the torus), but that also fails once the water reaches 100 degrees.

Now that you mention it... why not an injector (http://en.wikipedia.org/wiki/Injector)? Those are even simpler than steam engines combined with pumps.


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PostPosted: Mar 14, 2011 3:15 am 
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Udo Stenzel wrote:
gturner6ppc wrote:
Obsolete or not, I'd think a simple 19th-century steam engine (minus the boiler) directly connected to the cooling pumps via a clutch, as a redundancy in the emergency cooling system, would've been an improvement over waiting for someone to show up with another diesel generator.


Believe it or not, BWRs actually have steam driven coolant injection pumps. They still need electric power to operate the valves, but batteries are enough for that, the diesels aren't needed. This system is what cooled Fukushima 1 for the first 8 hours after the tsunami hit, then the batteries ran dry. I wonder what they do with the steam, though. It's probably condensed in the suppression system (the torus), but that also fails once the water reaches 100 degrees.

Now that you mention it... why not an injector (http://en.wikipedia.org/wiki/Injector)? Those are even simpler than steam engines combined with pumps.


Oh, an injector would be even better. A few months ago I was reading a book on kiln & forge design and the author related how one of the old hands also rigged their blower fan with an injector fed from a compressed air tank. That way if they had a power outage they could keep the burners running for several hours by the multiplier effect of using an injector. But it wouldn't make cool choo-choo sounds.

I've just heard that a third reactor has suffered a hydrogen explosion (the #2 reactor), but I haven't found direct confirmation.

Strangely enough, if the plants had been LFTRs instead of BWRs, the reactor operators would now probably be somewhere outside trying to aid in the tsunami recue efforts.


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PostPosted: Mar 14, 2011 4:07 am 
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gturner6ppc wrote:
Strangely enough, if the plants had been LFTRs instead of BWRs, the reactor operators would now probably be somewhere outside trying to aid in the tsunami recue efforts.


The best aid they could give would be to make electricity. Perhaps help fix power lines if these are down. Best still if they had an on-site desalination plant.


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PostPosted: Mar 14, 2011 2:32 pm 
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Notice that the newer BWR units at Fukushima II did not compromise decay heat removal functions, and do not have damaged fuel. They have more redundant and more passive cooling features.

And even those BWR-5 units are pretty old. The even newer ABWRs would suffer even less. For future passive BWR designs such as ESBWR, it would be a simple demonstration of their passive safety features! Such modern BWRs have much larger inherent heat sinks and fully passive core cooling, as well as even more robust containments.

No one is building older BWRs, Chernobyls, or Three Mile Island PWRs anymore. That's a crucial point.


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PostPosted: Mar 14, 2011 2:39 pm 
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An even more crucial point. Even these older units took a magnitude 9 earthquake and the public exposure is roughly a dental x-ray worth. Compare that to the dam that burst or the oil refinery still burning out of control. I like William Tucker's writeup in the Wall Street Journal.


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PostPosted: Mar 14, 2011 2:47 pm 
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Joined: Nov 23, 2010 6:51 pm
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Udo Stenzel wrote:
gturner6ppc wrote:
Obsolete or not, I'd think a simple 19th-century steam engine (minus the boiler) directly connected to the cooling pumps via a clutch, as a redundancy in the emergency cooling system, would've been an improvement over waiting for someone to show up with another diesel generator.


Believe it or not, BWRs actually have steam driven coolant injection pumps. They still need electric power to operate the valves, but batteries are enough for that, the diesels aren't needed. This system is what cooled Fukushima 1 for the first 8 hours after the tsunami hit, then the batteries ran dry. I wonder what they do with the steam, though. It's probably condensed in the suppression system (the torus), but that also fails once the water reaches 100 degrees.

Now that you mention it... why not an injector (http://en.wikipedia.org/wiki/Injector)? Those are even simpler than steam engines combined with pumps.


Why not use the same system to generate enough electricity to keep the valves operating as long as needed? If an active heat sink is needed to avoid having to vent steam, internally generated power to operate that would be useful too.

Such a system would not only improve safety, it would prevent nuclear powerplants from becoming a drain on the grid after shut down.


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PostPosted: Mar 14, 2011 3:05 pm 
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Location: Albuquerque NM USA
gturner6ppc wrote:
Obsolete or not, I'd think a simple 19th-century steam engine (minus the boiler) directly connected to the cooling pumps via a clutch, as a redundancy in the emergency cooling system, would've been an improvement over waiting for someone to show up with another diesel generator.

They run on steam (obviously), they always work, they're almost bullet-proof, and even 19th-century farmers could maintain and operate them. There are thousands of designs with decades of service history in extreme environments, including ships and locomotives.

I assume nobody ever tried such a crazy thing because it would've been such a jarring disconnect to see the scientific advancements of the atomic age hooked to a clunky steam engine from their grandfather's era.

But you wouldn't have to worry about diesel fuel contamination, diesel fuel quantity, fuel filters, oil filters, fuel injectors, glow plugs, the diesel starter motor, starter batteries, the water level in the starter batteries, the generator set, breakers, pump motor controller electronics, and a pump motor.

All you'd have is a pressure gage, a manual valve, and a throttle lever, all of which could be operated remotely with just mechanical linkages.

Of course with passive cooling you eliminate the whole system.


Sometimes the glamour of modern high-tech equipment causes people to lose sight of older and simpler technologies which are often better.


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PostPosted: Mar 14, 2011 3:23 pm 
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That's true. Advanced BWRs are naturally evolving to be simpler. The simplest is the ESBWR:

http://www.youtube.com/watch?v=vmHmSOf7oCA


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