Japan Earthquake: Nuclear Plants at Fukushima Daiichi

In summary: RCIC consists of a series of pumps, valves, and manifolds that allow coolant to be circulated around the reactor pressure vessel in the event of a loss of the main feedwater supply.In summary, the earthquake and tsunami may have caused a loss of coolant at the Fukushima Daiichi NPP, which could lead to a meltdown. The system for cooling the reactor core is designed to kick in in the event of a loss of feedwater, and fortunately this appears not to have happened yet.
  • #8,541
htf said:
I think NUCENG made a simple conversion error - it get 2 m^3/sec (see my previous post). So it is not that much. Compare it to a steam train which has about the same power (3MW for a big one is realistic).


Besides it is a different NPP I think the effect is simply related to the bright sun light that is reflected towards the camera by the left building.

Nope, no conversion error. When writing my post I copied the number wrong. Thanks.
 
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  • #8,542
I know that some generators were in inspection/modyfication, so they were offline and doesn't turn on
 
  • #8,543
Borek said:
Are the diesels already repaired? If not, oil leaks don't matter much. That is - they add to the mess, but they don't make the system more vulnerable.

one generator (and only one) was working after earthquake (this for unit 5,6), there is power lines and generators drawing in this big report which was posted here some pages back
 
  • #8,544
tonio said:
OK. Some remarks. If I am correct, the size of R4 building is 35 x 45 m. Assuming that the height of the refuelling floor is close to 15 m, it;'s volume is about 20.000 m^3, about a tenth of what you specify. This space, which I assume is well isolated (apart from the open blowout panels) and is not mechanically ventilated anymore, is heated by a large SPF, which generates about 3 MW of heat. I am not a physicist, but I assume that such a powerfull heat source, dumping an amount of steam in this space which is enough to fill it completely in just 1,5 minutes, will heat it to a temperature close to 100 degrees and will effectively refresh it's (steamy) atmosphere every few minutes.

I used 19260 m^3 in my calculation for refuel floor volume. Did I copy another number wrong? As pointed out by others I miscopied the 2.0 m^3/sec steam rate as 20 m^3/sec.
 
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  • #8,545
Gary7 said:
From the TV Asahi website

On the afternoon of March 31st at Fukushima Daiichi there was a large explosion heard near reactor #4. The explosion is believed to have been caused by a pressurized tank rupturing.
...
http://news.tv-asahi.co.jp/ann/news/web/html/210531044.html [Broken]

Shouldn't that be May 31st? A simple typo today but in the future someone might search the thread looking for info about this latest explosion and get the wrong idea.
 
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  • #8,546
NUCENG, I think this is what he was referring to...
NUCENG said:
... That 20 m^3/sec will not result in a flow out the openings of 20 m^3/sec. The approximate volume of the refuel floor is about 2E5 m^3. It will be hot and humid and there will be some steam dilution and mixing of hydrogen. However over time the hydrogen concentration has 24 hours from the minimum time I calculated to accumulate to the Lower Explosive Limit in the top of the bulding.

Maybe you meant to write 2E4 cubic meters :smile:
 
  • #8,547
MiceAndMen said:
Shouldn't that be May 31st? A simple typo today but in the future someone might search the thread looking for info about this latest explosion and get the wrong idea.

Yes - thanks for that. Now fixed.
 
  • #8,548
MiceAndMen said:
NUCENG, I think this is what he was referring to...


Maybe you meant to write 2E4 cubic meters :smile:

yep. Looks like I need a new set of hands so I can count zeros.
 
  • #8,549
First step set in getting SFP under control

Cooling system being tested at No. 2 reactor

[PLAIN said:
http://www3.nhk.or.jp/daily/english/31_26.html][/PLAIN] [Broken] The operator of the troubled Fukushima Daiichi nuclear power plant has installed a circulatory cooling system at one of the plant's crippled reactors.

The Tokyo Electric Power Company started trial operation of the system at the No. 2 reactor building on Tuesday.

The utility has been pumping about 50 tons of water into a used fuel pool in the building every few days.

The pool's temperature is around 70 degrees Celsius, apparently producing steam that is filling the building and resulting in a humidity level of 99.9 percent. The humidity and high radiation levels have been hampering repair work at the site.

The new system is to pump water out of the pool to a heat exchanger and return the water to the pool as coolant.

The firm says it plans to bring the pool's temperature to around 40 degrees Celsius in a month through the system.

TEPCO hopes to reduce the humidity level before installing equipment to remove radioactive substances in the building.

The cooling system is the first to be completed at the plant. The firm hopes to start operating similar systems at the plant's No. 1 and 3 reactors in June, and at the No. 4 reactor in July.
Tuesday, May 31, 2011 19:04 +0900 (JST)

SFP-2 is producing about 400kW compared to the 2 to 3 MW of SFP-4

Furthermore we soon will get to know where the steam is coming from - the fuel pool or the reactor.
Where is the steam produced in the reactor disappearing to?
 
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  • #8,550
But how they can do this without entering building ? And why they can't do this for other units ? Steam is not only from sfp, unit 2 is at atmospheric pressure and also we know that there is water leak from core to turbine building, so drywell/torus must be leaking also.
 
  • #8,551
elektrownik said:
But how they can do this without entering building ?

They may be tapping into the existing piping for the residual heat removal system (RHRS) for the SFP.

The regular heat exchanger for that should be in the turbine hall next door, from where they also do all the water injection into the core.

Originally, when they reconnected external power to the turbine halls after March 20 they talked about restarting the RHRS for the reactor core and SFP, but that never happened. Perhaps the motors for the pumps had been damaged by seawater.

They may have hooked up temporary pumps to the original RHRS pipes to the SFP.
 
  • #8,552
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  • #8,553
elektrownik said:
I know that some generators were in inspection/modyfication, so they were offline and doesn't turn on
So they operated the reactors without sufficient emergency power? Is this permitted? Station blackout has been considered one of the most likely and dangerous incidents - and we now know for sure it is!
 
  • #8,554
AntonL said:
Furthermore we soon will get to know where the steam is coming from - the fuel pool or the reactor.

A long documentary on the construction of Fukushima Daiichi was posted here a while ago. One interesting thing I learned from it is that there is a 5cm wide gap between the steel enclosure of the drywell (the "ligh bulb" part of the primary containment) and the surrounding concrete (aka secondary containment).

That gap makes sense of course to accommodate thermal expansion of the steel. But it means that steam leaking through the drywell, at a breach or ruptured flange anywhere, may travel withinh that gap and escape from the secondary containment at a completely different place. Isn't that so?

In particular, the steam that is seen leaking from the refueling pool in unit #3 may come from a leak much lower down on the drywell's wall.

I do not know what is the situation at the very bottom of the drywell, the part that is buried in the concrete. That part must be supporting a LOT of weight (drywell wall + rod actuators + inner concrete shield + pressure vessel + fuel + water in reactor + water in refueling pool + other stuff). So I would guess that it is resting on the underlying concrete, without any gap.
 
  • #8,555
Borek said:
Are the diesels already repaired? If not, oil leaks don't matter much. That is - they add to the mess, but they don't make the system more vulnerable.

According to this article:
http://search.japantimes.co.jp/cgi-bin/nn20110601a3.html" [Broken]
Tepco spokesman Junichi Matsumoto said the utility believes the leak probably started on or shortly after March 11, noting the tsunami moved the tanks more than 10 meters to the north.
They probably had more important things to do than search for and fix the inevitable leak.

There is a picture on Tepco's website of some oil (diesel?) on water.
http://www.tepco.co.jp/en/news/110311/images/110531_01.jpg"
 
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  • #8,556
Jorge Stolfi said:
A long documentary on the construction of Fukushima Daiichi was posted here a while ago. One interesting thing I learned from it is that there is a 5cm wide gap between the steel enclosure of the drywell (the "ligh bulb" part of the primary containment) and the surrounding concrete (aka secondary containment).

That gap makes sense of course to accommodate thermal expansion of the steel. But it means that steam leaking through the drywell, at a breach or ruptured flange anywhere, may travel withinh that gap and escape from the secondary containment at a completely different place. Isn't that so?

In particular, the steam that is seen leaking from the refueling pool in unit #3 may come from a leak much lower down on the drywell's wall.

I do not know what is the situation at the very bottom of the drywell, the part that is buried in the concrete. That part must be supporting a LOT of weight (drywell wall + rod actuators + inner concrete shield + pressure vessel + fuel + water in reactor + water in refueling pool + other stuff). So I would guess that it is resting on the underlying concrete, without any gap.
Yes, i remarked also this interesting point when i saw the video (they were putting a kind of wooden block to get the 5 cms gap if i remember well), and so you maybe be very right: if this enveloppe is damaged then steam will leak and move towards the top. I have no idea of how the design is done in the lower part of the containment, you are right, it's not possible in my mind to have this design there.

On this subject, maybe some infos here:https://netfiles.uiuc.edu/mragheb/www/NPRE%20457%20CSE%20462%20Safety%20Analysis%20of%20Nuclear%20Reactor%20Systems/Containment%20Structures.pdf [Broken]
(see page 2 drawing for a different containment, and page 18 a very nice drawing for BWR Mark I which shows the precise design in this bottom area: steel is embedded in the concrete)

http://140.116.36.16/paper/22.pdf [Broken]
 
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  • #8,557
Some hours ago there were reports about an explosion near R4. Watching the new webcam I see a building (rightmost one) near R4 which *seems* to smoke or burn.

Difficult to tell in detail, but I think something is going on there.

What building is this? Looks like the nuclear waste facility. What do the experts think?
 
  • #8,558
ottomane said:
Some hours ago there were reports about an explosion near R4. Watching the new webcam I see a building (rightmost one) near R4 which *seems* to smoke or burn.

Difficult to tell in detail, but I think something is going on there.

What building is this? Looks like the nuclear waste facility. What do the experts think?

Yes I see it also, this is between unit 2 and 3, but closer to 2, maybe this is connected to works to restore unit 2 sfp cooling ? Who know...
 
  • #8,559
Yep, just checked the Tepco webcam and wanted to report the smoke or steam coming out from the ground floor it seems of maybe N°3 (difficult to see in fact). But you already did it!
 
  • #8,560
Yes, there is sth. near R3 now. What I was referring to was the small building very right in the picture, but there is nothing to see now. Maybe they stopped the fire.
 
  • #8,561
htf said:
So they operated the reactors without sufficient emergency power? Is this permitted? Station blackout has been considered one of the most likely and dangerous incidents - and we now know for sure it is!

Well for the plants in the US, the operability of the EDGs is controlled by the plant Technical Specifications. These Tech Specs (part of the plant license) are sort of like a procedure that describes what must be done when any of the safety systems is degraded. Failure to follow the Tech Specs will get you fired and get the plant a big fine.

As far as the emergency diesels, typically each reactor has two EDGs; and the Tech Specs say if one EDG is inoperable, the operators have 8 hours to verify that the other EDG is OK (by testing it), and then they have a specified time (7 days) to fix the broken EDG. If they can't fix it in that time, then they have to shut the plant down. The times (8 hrs and 7 days above) might vary from plant to plant.
 
  • #8,562
http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/11053106_table_summary-e.pdf

The RPV bellow seal temperature sensor of unit 2 is back and registering at 182 Celsius
 
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  • #8,563
GJBRKS said:
http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/11053106_table_summary-e.pdf

The RPV bellow seal temperature sensor of unit 2 is back and registering at 182 Celsius

And N°3 is again rising at 219,7 °C. If the sensors work, then no doubt, this thing is alive and changing...

In fact, there has been a big surge again it seems on this temperature, at RPV Bellows seal, in reactor n°3:

http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/11053106_temp_data_3u-e.pdf

Any idea of what this could indicate, ads this is not the first time?
 
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  • #8,564
elektrownik said:

From the article:

The water, recently found in the basement of the No. 1 reactor building of the nuclear power plant, contained 30,000 becquerels of iodine-131 per cubic centimeter, 2.5 million becquerels of cesium-134 and 2.9 million becquerels of cesium-137.

... The amount is estimated at 2,700 tons.

The water is believed to have leaked into the basement from the reactor pressure vessel and the container that houses the vessel.

OK physics/math people, help me out here. The first thing I did was calculate, based on that data, the total amount (In Curies) of radioactivity in the new water found.

I must have done something seriously wrong. The totals I get are unbelievable.

2.5 million becquerels of cesium-134 per cubic centimeter
The amount is estimated at 2,700 tons

2.5 million X 1000 = becquerels per liter, 2.5 x 109

2.5 x 109 X 1000 = becquerels per metric ton of water, 2.5 X 1012

x 2,700 = total becquerels of C-134 in the water, 6.750 x 1015

(assuming tons = metric tons)

Any problem with that? Then divide by 1 Ci = 3.7×1010

1.82432432 X105

You tell me, is that right? That's about 182,432 Curies of cesium-134, in just the basement.

To compare, Chernobyl released 54,000 Ci of cesium-134 and 1,100,000 Ci of cesium-137

So either I made a math mistake, or just in the one basement there is way way more cesium-134 than Chernobyl released. Can that be right?
 
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  • #8,565
robinson said:
From the article:
You tell me, is that right? That's about 182,432 Curies of cesium-134, in just the basement.

To compare, Chernobyl released 54,000 Ci of cesium-134 and 1,100,000 Ci of cesium-137

So either I made a math mistake, or just in the one basement there is way way more cesium-134 than Chernobyl released. Can that be right?

My math agrees with yours to an order of magnitude, so I don't think there's any problems with the arithmetic. However, I think the Chernobyl release was on the order of 1016 Bequerels for both Cs-134 and Cs-137 as opposed to 1015 in the reactor 1 basement. I still wouldn't want to go swimming there, though.

Page 9
http://www.osti.gov/bridge/servlets/purl/5027173-rumHCE/5027173.pdf

Page 39
http://oberon.sourceoecd.org/vl=136...psv=/ij/oecdjournals/16091914/v3n1/s1/p1l.idx
 
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  • #8,566
1,100,000 Ci of cesium-137 = 1.1 x 1016 Bequerels

I used the C-134 figure because it came out much higher than the Chernobyl figure for C-134
 
  • #8,567
Aha! I think I found the problem. The figures I used for Chernobyl is the amount released over Europe, not the total amounts. So my math was correct. The problem was comparing amounts to the fallout from Chernobyl over Europe, which isn't the same thing as the total amount at all.
 
  • #8,568
Using the simple formula I derived http://www.bautforum.com/showthread...odine-in-nuclear-waste?p=1893658#post1893658", I get that the radioactivity of Cs-134 is about 1290 Ci/g, which means there's about 141 g of Cs-134 in those 2700 tons of water, which given that it's highly soluble in water isn't a strange amount.

That the levels hasn't changed much is actually an indication that it's a result of a single leak, not a continuing one, as the half life of Cs-134 is about 2 years, so if it had been continuously release there would have been a steady increase in the level.
 
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  • #8,569
Those are the official numbers for Chernobyl, I believe:

http://www.oecd-nea.org/rp/chernobyl/c02.html

54 PBq Cs-134 release in Chernobyl, there's 6 PBq Cs-134 in the water in Fukushima. So that's the problem. Your Cs-134 numbers for Chernobyl are wrong. But I see, you figured it out yourself... ^^

There's additionally ~8 PBq Cs-137. That's the size of the atmospheric release. The size of the Fukushima Cs fallout all over Japan, the Pacific and the world concentrated in 2700 tons of water. Yummy...
 
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  • #8,570
clancy688 said:
54 PBq Cs-134 release in Chernobyl, there's 6 PBq Cs-134 in the water in Fukushima.

Actually there are around 12Pbq of Cesiums in one basement there. Which they just found.
 
  • #8,571
Do we not need to adjust the amount of water to include the rest of the site?
If there is about 100,000 tons of similarly contaminated water in the entire plant, that would suggest about 12Pbq *100,000/2700 = about 440 Pbqs of Cesium at Fukushima.
Seems that AREVA really has a job to do.
Has anyone any idea whether their selective precipitation techniques have a prayer of working on this minute quantity of cesium, ( about 0.05 gram/ton) from a salt water solution? They claimed 99.9% to 99.99% removal, but that seems just heroic to me, based on my long ago chemistry background.
 
  • #8,572
I have a couple questions:
• What is the current status of reactors 1-4?
• What techniques/work have nuclear engineers done to achieve this status?
• Are reactors 5 and 6 really worth mentioning relative to 1-4?
 
  • #8,573
Derpin said:
I have a couple questions:
• What is the current status of reactors 1-4?
• What techniques/work have nuclear engineers done to achieve this status?
• Are reactors 5 and 6 really worth mentioning relative to 1-4?
You ask some questions with potentially some very long answers ;) You might start here:
http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1306898792P.pdf [Broken]
or here
http://en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disaster
 
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  • #8,574
jlduh said:
And N°3 is again rising at 219,7 °C. If the sensors work, then no doubt, this thing is alive and changing...

In fact, there has been a big surge again it seems on this temperature, at RPV Bellows seal, in reactor n°3:

http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/11053106_temp_data_3u-e.pdf

Any idea of what this could indicate, ads this is not the first time?

My idea is that they had trouble cooling during the tropical storm.
The main cooling agent is water turning to steam.
I think that a lot of steam recondensed.
They also reduced the amount of water injected before that.
Cooling is now returning to prestorm levels again
 
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  • #8,575
HenrikOlsen said:
That the levels hasn't changed much is actually an indication that it's a result of a single leak, not a continuing one, as the half life of Cs-134 is about 2 years, so if it had been continuously release there would have been a steady increase in the level.
Hmmm ... what didn't change? The total activity of the water in the basement or the activity per cm^3? If the latter was the case I would conclude quite the opposite.
 
<h2>1. What caused the Japan earthquake and subsequent nuclear disaster at Fukushima Daiichi?</h2><p>The Japan earthquake, also known as the Great East Japan Earthquake, was caused by a massive underwater earthquake that occurred on March 11, 2011. The earthquake had a magnitude of 9.0 and was the strongest ever recorded in Japan. The earthquake triggered a massive tsunami, which caused extensive damage to the Fukushima Daiichi nuclear power plant and led to a nuclear disaster.</p><h2>2. What is the current status of the nuclear reactors at Fukushima Daiichi?</h2><p>As of now, all of the nuclear reactors at Fukushima Daiichi have been shut down and are no longer in operation. However, the site is still being monitored for radiation levels and there is an ongoing effort to clean up the radioactive materials that were released during the disaster.</p><h2>3. How much radiation was released during the Fukushima Daiichi nuclear disaster?</h2><p>According to the International Atomic Energy Agency, the Fukushima Daiichi nuclear disaster released an estimated 10-15% of the radiation that was released during the Chernobyl disaster in 1986. However, the exact amount of radiation released is still being studied and debated.</p><h2>4. What were the health effects of the Fukushima Daiichi nuclear disaster?</h2><p>The health effects of the Fukushima Daiichi nuclear disaster are still being studied and monitored. The most immediate health impact was the evacuation of approximately 160,000 people from the surrounding areas to avoid exposure to radiation. There have also been reported cases of thyroid cancer and other health issues among those who were exposed to the radiation.</p><h2>5. What measures have been taken to prevent future nuclear disasters in Japan?</h2><p>Following the Fukushima Daiichi nuclear disaster, the Japanese government has implemented stricter safety regulations for nuclear power plants and has conducted stress tests on all existing plants. They have also established a new regulatory agency, the Nuclear Regulation Authority, to oversee the safety of nuclear power plants. Additionally, renewable energy sources are being promoted as a more sustainable and safer alternative to nuclear power in Japan.</p>

1. What caused the Japan earthquake and subsequent nuclear disaster at Fukushima Daiichi?

The Japan earthquake, also known as the Great East Japan Earthquake, was caused by a massive underwater earthquake that occurred on March 11, 2011. The earthquake had a magnitude of 9.0 and was the strongest ever recorded in Japan. The earthquake triggered a massive tsunami, which caused extensive damage to the Fukushima Daiichi nuclear power plant and led to a nuclear disaster.

2. What is the current status of the nuclear reactors at Fukushima Daiichi?

As of now, all of the nuclear reactors at Fukushima Daiichi have been shut down and are no longer in operation. However, the site is still being monitored for radiation levels and there is an ongoing effort to clean up the radioactive materials that were released during the disaster.

3. How much radiation was released during the Fukushima Daiichi nuclear disaster?

According to the International Atomic Energy Agency, the Fukushima Daiichi nuclear disaster released an estimated 10-15% of the radiation that was released during the Chernobyl disaster in 1986. However, the exact amount of radiation released is still being studied and debated.

4. What were the health effects of the Fukushima Daiichi nuclear disaster?

The health effects of the Fukushima Daiichi nuclear disaster are still being studied and monitored. The most immediate health impact was the evacuation of approximately 160,000 people from the surrounding areas to avoid exposure to radiation. There have also been reported cases of thyroid cancer and other health issues among those who were exposed to the radiation.

5. What measures have been taken to prevent future nuclear disasters in Japan?

Following the Fukushima Daiichi nuclear disaster, the Japanese government has implemented stricter safety regulations for nuclear power plants and has conducted stress tests on all existing plants. They have also established a new regulatory agency, the Nuclear Regulation Authority, to oversee the safety of nuclear power plants. Additionally, renewable energy sources are being promoted as a more sustainable and safer alternative to nuclear power in Japan.

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