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Old 03-13-2011, 06:22 PM   #286
IronRain
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Quote:
Originally Posted by Urwumpe View Post
 Why bad? It just is a measurement. The miracle of plate tectonics in practical applications maybe.
Well, the planet moved 10 cm on its axis just sounds bad..
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Old 03-13-2011, 06:29 PM   #287
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Originally Posted by IronRain View Post
 Well, the planet moved 10 cm on its axis just sounds bad..
Yes, but that is wrong. The intersection of the Earth axis on the surface of Earth moved by mere 10 cm. Or: 0.0005 seconds of arc. Its a tiny wobble cause by the massive shift of mass on it.
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Old 03-13-2011, 06:30 PM   #288
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By comparison, Wikipedia has the following about last year's Chile earthquake of 8.8

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Geophysical impact
Seismologists estimate that the earthquake was so powerful that it may have shortened the length of the day by 1.26 microseconds and moved the Earth's figure axis by 8 cm or 2.7 milliarcseconds. Precise GPS measurement indicated the telluric movement moved the entire city of Concepción 3.04 meters (10 ft) to the west. The capital Santiago experienced a displacement of almost 24 centimeters (10 in) west, and even Buenos Aires, about 1,350 kilometres (840 mi) from Concepción, shifted 3.9 centimeters (1.5 in). It is estimated that Chile's territory could have expanded 1.2 km² as a result.
http://en.wikipedia.org/wiki/2010_Ch...hysical_impact

Last edited by Belisarius; 03-13-2011 at 06:36 PM.
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Old 03-13-2011, 06:37 PM   #289
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"The whole island of Honshu was shifted 2.4 metres to the west by the quake on Friday."
Then all the GPS maps and navigation reference points become false ? For some applications, 2.4 meters can make a difference.
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Old 03-13-2011, 06:44 PM   #290
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It is normal for such large earthquakes. After 2004 Indonesian earthquake some islands were moved over 30 meters horizontaly and shifted few meters vertically. Ocean floor were shifted up and down in some places several dozen meters. It is not uncommon for low lying areas to become submerged as a result from vertical shifts. I wouldn't be suprised if some towns (or places were they used to be) in Japan after this become a new seabed.
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Old 03-13-2011, 07:13 PM   #291
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Are there any Japanese speakers around? The NISA web site in English lags (understandably) behind the Japanese version.

Re: Onagawa. If there are any underground pipes, this could be some tritiated water leaking (a wild guess). Or, Tohoku EPCO has been successful in covering up another meltdown.
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Old 03-13-2011, 07:21 PM   #292
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5 reactors are now overheating. There could be rain tomorrow, that would bring fine radioactive particles on the ground. Also, the meteo forecast says that winds are going to turn, blowing eastwards.
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Old 03-13-2011, 07:58 PM   #293
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Tokai 2 has two out of three emergency cooling diesel-generators down. Source: http://uk.reuters.com/article/2011/0...72C2RL20110313
(cited by Wiki, verified by /me)
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Old 03-13-2011, 08:00 PM   #294
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There clearly has to be more seious breakdowns than just lack of electricity to run the coolant pumps. The TEPCO press release even say offsite power is available so they should be able to power up the pumps regardless of broken down diesel generators and bring temperature and pressure under control if all the neccesary cooling system hardware is in working order like it was claimed earlier. No1 reactor may have cooling system damage from explosion, but No 3 which appearently is on the verge of meltdown had no explosion.
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Old 03-13-2011, 10:12 PM   #295
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Quote:
Originally Posted by Urwumpe View Post
 Well, a few kilometers would be better if you remember how far the water retreats, so the cable length and other factors could sure mean that this solution is not feasible at all. It would likely risk the safety of another nuclear reactor.

Much better and more reliable would be simply being able to plug emergency power from a fire truck or other normal land based emergency forces into any nuclear reactor cooling system. The problem is not having enough power available for pumping only 875 liters of water every second (one bath tub per second), the problem is just connecting it into the system.
Do you have a source for that 875 liters per second number?
Note this is not really a small amount at a per second rate. This is close to a cubic meter per second. This is a good fraction of some discharge rates for the River Thames in England depending on location:

River Thames - Wikipedia, the free encyclopedia River Thames - Wikipedia, the free encyclopedia


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Old 03-13-2011, 10:36 PM   #296
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875 liters for a bathtub ? 300 liters is already a big bathtub
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Old 03-13-2011, 11:12 PM   #297
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Quote:
Originally Posted by N_Molson View Post
 875 liters for a bathtub ? 300 liters is already a big bathtub
Some people have less displacement.

Quote:
Originally Posted by RGClark View Post
 Do you have a source for that 875 liters per second number?
Note this is not really a small amount at a per second rate. This is close to a cubic meter per second. This is a good fraction of some discharge rates for the River Thames in England depending on location:
I calculated it by the information that a shutdown reactor produces 7% of thermal power of its rated maximal thermal power in the first hours after shutdown. By the technical data of the similar US BWRs (publicly available) 12.5 m³ are needed for cooling the reactor at 100% power.
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Old 03-13-2011, 11:27 PM   #298
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Quote:
Originally Posted by RGClark View Post
 Do you have a source for that 875 liters per second number?
Note this is not really a small amount at a per second rate. This is close to a cubic meter per second. This is a good fraction of some discharge rates for the River Thames in England depending on location:

River Thames - Wikipedia, the free encyclopedia

Bob Clark
Urwumpe's numbers are good estimates. 300,000 gallons per minute or a bit over 18 cubic meters per second. The circulation pumps in PWRs are *impressive* and move a lot of water.

Last edited by Thunder Chicken; 03-13-2011 at 11:29 PM.
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Old 03-13-2011, 11:28 PM   #299
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Quote:
Originally Posted by Urwumpe View Post
 Some people have less displacement.
I calculated it by the information that a shutdown reactor produces 7% of thermal power of its rated maximal thermal power in the first hours after shutdown. By the technical data of the similar US BWRs (publicly available) 12.5 m³ are needed for cooling the reactor at 100% power.
Thanks for that.
For the first reactor that lost its cooling systems, its understandable why the mobile generators trucked in couldn't start the cooling systems after the explosion.
Anyone know why the mobile diesel generators are not able to operate the cooling systems at that second reactor now without its main and emergency cooling systems?
I've seen some explanations that "the plugs didn't fit". That doesn't seem like a reasonable explanation. You cut off the plugs and weld the cables together if you have to.


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Old 03-13-2011, 11:43 PM   #300
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Quote:
Originally Posted by Urwumpe View Post
 
I calculated it by the information that a shutdown reactor produces 7% of thermal power of its rated maximal thermal power in the first hours after shutdown. By the technical data of the similar US BWRs (publicly available) 12.5 m³ are needed for cooling the reactor at 100% power.
Let me help you here; the decay heat associated with a reactor that has been on-line for a period of at least a few weeks is, following shutdown, (and in percent of the rated full thermal power of the reactor) is approximately as follows:

Instantanenously at shutdown = 7%
1 second following shutdown = 6%
1 minute following shutdown = 3.5%
1 hour following shutdown = 1%

Decay heat, named as such from the decay of the fission products, follows a natural exponential decay. Most auxillary feedwater systems in commerical reactors (and I'm specifically discussing PWRs here; the Japan reactors in question are actually BWRs) is usually rated for 4% to 5% of rated full power and therefore by the time the pumps and systems start and get going, the decay heat load has dropped to within the capability of the systems.

So, the 7% number is actually too large for this type of calculation.
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