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Latest NEI UPDATE AS OF 10:00 A.M. EDT, SUNDAY, MARCH 20: Fukushima [What Is Criticality?]
NEI ^ | SUNDAY, MARCH 20, 2011 | NEI

Posted on 03/20/2011 9:59:46 AM PDT by fight_truth_decay

A two-part operation to spray water into the used fuel pool at Fukushima Daiichi reactor 4 ended just before 7 A.M. EDT. Japan's defense ministry announced that the Self Defense Force discharged more than 100 tons of water at the pool, and concluded that much of it reached inside the reactor building.

This was the first time since the March 11 quake that reactor 4 has been doused. Yesterday the Tokyo elite fire services used a high-pressure fire truck to spray water for more than 13 hours into the fuel pool of reactor 3.

The ministry also reported conducting surface temperature measurements of reactors 1 through 4 from a helicopter to evaluate the effect of the water discharge operations. The surface temperature of each unit is below 100 degrees Celsius.

Tokyo Electric Power Co. said this morning that pressure within the reactor containment vessel from reactor 3 has begun to stabilize and has decided against an operation to vent gases to reduce pressure inside the containment vessel.

TEPCO is continuing work to restore electricity to reactor 2. A power cable has been connected from a nearby transmission line. TEPCO hopes to have power restored to the reactor's control room sometime today. Connections to reactors 1, 3, 4, 5, and 6 are to follow.

(Excerpt) Read more at nei.cachefly.net ...


TOPICS: Breaking News; Culture/Society; Extended News; Japan; News/Current Events
KEYWORDS: fukushima; mit; nei; tepco
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To be updated soon the MIT NSE Nuclear Information Hub.

What does the term criticality mean?

Posted on March 18, 2011 9:52 pm UTC by mitnse[MIT nse]

The words “criticality” and “re-criticality” have been used extensively in the media coverage. Criticality is a nuclear term that refers to the balance of neutrons in the system. “Subcritical” refers to a system where the loss rate of neutrons is greater than the production rate of neutrons and therefore the neutron population (or number of neutrons) decreases as time goes on. “Supercritical” refers to a system where the production rate of neutrons is greater than the loss rate of neutrons and therefore the neutron population increases. When the neutron population remains constant, this means there is a perfect balance between production rate and loss rate, and the nuclear system is said to be “critical.”

Therefore, when a reactor is said to have “gone critical,” it actually means it is in a stable configuration producing a constant power.

Updates from my past posts: http://www.freerepublic.com/focus/f-news/2690864/posts


1 posted on 03/20/2011 9:59:50 AM PDT by fight_truth_decay
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To: fight_truth_decay

Very good news about the pressure at no. 3.


2 posted on 03/20/2011 10:02:31 AM PDT by mojito
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To: fight_truth_decay
Therefore, when a reactor is said to have “gone critical,” it actually means it is in a stable configuration producing a constant power.

It will still melt if something doesn't carry that power off. Constant power doesn't mean constant temperature.

3 posted on 03/20/2011 10:02:59 AM PDT by Lonesome in Massachussets (Sulzberger Family Motto: Trois generations d'imbeciles, assez)
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To: Lonesome in Massachussets

100 tons of water sounds like a lot to the untrained ear. A 60’s era Air Force P-2 could pump that in a little over 20 minutes.


4 posted on 03/20/2011 10:18:36 AM PDT by Old Flat Toad (Pima County, home of the single vehicle accident with 40 victims.)
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To: Old Flat Toad
100 tons of water sounds like a lot to the untrained ear. A 60’s era Air Force P-2 could pump that in a little over 20 minutes.

You're right. On a personal scale, yeah, 100 tons is a lot of water. (unless you're a teenager showering!) On an industrial scale, that's not much at all.

Consider, at 8.35 lbs per gallon, that's only about 24K gallons. If I remember correctly, my Dad one-time figured our local pool held about 29K gallons. It is just your average 25m long, by 6 lane wide (for swim meets) with an offset 10 ft deep diving area.

Or for a different visual, consider the typical semi tanker truck that delivers fuel to your local gas station. These have a capacity between 5K and 9K gallons. So we're talking about just 3 of them. Not a lot of water.

5 posted on 03/20/2011 10:50:38 AM PDT by ThunderSleeps (Stop obama now! Stop the hussein - insane agenda!)
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To: Old Flat Toad

if my math is right (and not talking about sea water which is difficult to measure exactly) we are talking about 23,952 pounds of water. Water weighs 8.35 pounds. Seawater a little more as it is denser. I used fresh water for the math.


6 posted on 03/20/2011 10:51:03 AM PDT by fred2008
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To: fred2008

Roughly, a gallon of salt water weighs 8.556 lbs.


7 posted on 03/20/2011 10:53:26 AM PDT by fred2008
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To: fight_truth_decay

Supplying power is fine but it hasn’t been established that the pumps, valves, etc. are functional.


8 posted on 03/20/2011 11:04:38 AM PDT by upcountryhorseman (An old fashioned conservative)
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To: upcountryhorseman

UPDATE: (20 March 2011, 16:20 UTC)
Japanese authorities have notified the IAEA of progress at the Fukushima Daiichi nuclear power plant. Workers today have successfully placed reactor Unit 5 (at 05:30 UTC) and 6 (at 10:27 UTC) into cold shutdown.

This means that the reactors are in a safe mode, with cooling systems stable and under control, and with low temperature and pressure within the reactor.

Officials are continuing efforts to restore plant systems at Daiichi Units 1-3.

Unit 4 had been shut down for maintenance, with all its fuel removed from the reactor core, before the 11 March earthquake.

Eight other reactors at the Fukushima Daini, Onagawa, and Tokai nuclear power plants were shut down automatically after the earthquake and all are now in cold shutdown.

http://iaea.org/newscenter/news/tsunamiupdate01.html


9 posted on 03/20/2011 11:14:32 AM PDT by fight_truth_decay
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To: fight_truth_decay

So what’s the bottom line here? It seems hard to follow these reports and get a real sense of what’s going on unless you want to spend an hour a day reading.


10 posted on 03/20/2011 11:17:02 AM PDT by Jeff Winston
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To: fight_truth_decay

I figured things were getting better, as this news has been completely wiped from the Drama Media. Now they’re talking about Libya.


11 posted on 03/20/2011 11:32:54 AM PDT by ponygirl
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To: Jeff Winston
So what’s the bottom line here?

The world has lost:

1) Another fission reactor.
2) 3000 square kilometers to human habitation for the generations.
3) Billions of dollars productivity and capital.
4) Widening mistrust of the production of energy through nuclear fission.

12 posted on 03/20/2011 11:43:48 AM PDT by Amerigomag
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To: fight_truth_decay

Here’s my prediction.

Now that almost all (all?) foreign journalists have withdrawn from Japan, and now that the only source of information appears to be from TEPCO, which has been repeatedly proven to lie about just about everything over the last few decades, I predict that everything will be fine - until suddenly it isn’t.


13 posted on 03/20/2011 11:54:04 AM PDT by catnipman (Cat Nipman: Made from the right stuff!)
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To: Lonesome in Massachussets; fight_truth_decay
In order to maintain a stable condition, it is necessary to adjust the system to keep the loss of neutrons the same as the gain. That is the purpose of the control rods which absorb neurons and are moved up and down slightly to maintain a stable condition.

Otherwise the system goes subcritical (the 'fire' goes out) or supercritical (meltdown).

14 posted on 03/20/2011 12:07:20 PM PDT by expatpat
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To: catnipman

>> Now that almost all (all?) foreign journalists have withdrawn from Japan

Are you claiming that *journalists* are to be trusted? ROFL


15 posted on 03/20/2011 12:19:50 PM PDT by Nervous Tick (Trust in God, but row away from the rocks!)
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To: Nervous Tick

Not at all. It’s just that now we have only TEPCO issuing reports. At least with multiple reporters from multiple countries we’d get some different perspectives, since it would be unlikely that all news media from all countries could simultaneously gen up exactly the same spin.


16 posted on 03/20/2011 12:26:35 PM PDT by catnipman (Cat Nipman: Made from the right stuff!)
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To: catnipman

>> At least with multiple reporters from multiple countries we’d get some different perspectives, since it would be unlikely that all news media from all countries could simultaneously gen up exactly the same spin.

You *are* naive, FRiend. Journalists of ALL countries are socialist vermin, EVERY BIT as agenda driven as is TEPCO.


17 posted on 03/20/2011 12:28:47 PM PDT by Nervous Tick (Trust in God, but row away from the rocks!)
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To: Amerigomag

“2) 3000 square kilometers to human habitation for the generations.”

So much?! Do you have a source for that or is it a typo?


18 posted on 03/20/2011 12:47:36 PM PDT by Eyes Unclouded ("The word bipartisan means some larger-than-usual deception is being carried out." -George Carlin)
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To: Amerigomag
3000 square kilometers to human habitation for the generations.

What are Hiroshima and Nagasaki?

19 posted on 03/20/2011 12:49:46 PM PDT by T. P. Pole
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To: expatpat
That is the purpose of the control rods which absorb neurons and are moved up and down slightly to maintain a stable condition.

Thanks..

20 posted on 03/20/2011 12:53:46 PM PDT by fight_truth_decay
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