Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[joewein]

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.

 

[GJBRKS]

http://www.tepco.co.jp/nu/f1-np/camera/index-j.html

The nighttime newly installed webcam view shows a pattern of random excitations on the CCD ,
I'm wondering wether these might be high energy decay photons from the surrounding radioactivity ? ?

 

[htf]

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!

 

[Jorge Stolfi]

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.

 

[Bandit127]

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"
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"

 

[jlduh]

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
(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

 

[ottomane]

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?

 

[elektrownik]

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...

 

[jlduh]

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!

 

[ottomane]

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.

 

[gmax137]

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.

 

[GJBRKS]

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

 

[jlduh]

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?

 

[robinson]

http://jen.jiji.com/jc/eng?g=eco&k=2011053000813"

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?

 

[thehammer2]

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

 

[robinson]

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

 

[robinson]

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.

 

[HenrikOlsen]

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.

 

[clancy688]

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...

 

[robinson]

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.

 

[etudiant]

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.

 

[Derpin]

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?

 

[StrangeBeauty]

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
or here
http://en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disaster

 

[GJBRKS]

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

 

[htf]

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.

 

[tsutsuji]

[The NISA] is asking TEPCO to secure new storage sites to which the contaminated water can be quickly transferred,
http://www3.nhk.or.jp/daily/english/01_24.html

The water levels as of May 31st 7 AM JST reported on http://www.tepco.co.jp/nu/fukushima-np/images/handouts_110531_01-j.pdf (as of May 19th 7 AM JST http://www.tepco.co.jp/nu/fukushima-np/images/handouts_110519_03-j.pdf ) are :

unit 2 trench : OP + 3606 mm (OP + 3240 mm : May 19th 7 AM)
unit 3 trench : OP + 3706 mm (OP + 3360 mm : May 19th 7 AM)

unit 2 : (3606-3240)/(31-19)=30.5 mm/day
unit 3 : (3706-3360)/(31-19)=28.8 mm/day

The ground level near the pits is OP + 4000 mm : http://www.tepco.co.jp/nu/fukushima-np/f1/images/f1-sv-20110323-j.pdf

So how many days are left until this level is reached ?

unit 2 : (4000-3606)/30.5=12.9 days ~ June 13th
unit 3 : (4000-3706)/28.8=10.2 days ~ June 10th

It was reported that work was undergone to fill the pits with concrete, but is it enough ?

Accumulated water maps have been released : http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110530_04-e.pdf

Water level in the basement of unit 1 reactor building has decreased by 6 mm between May 31st 5 PM and June 1st 7 AM, making people wonder where that water has gone : http://www3.nhk.or.jp/news/html/20110601/t10013249251000.html

 

[Rive]

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

IMO the main feedwater line is broken and the core has no cooling now.

Maybe it's possible to calculate a raw core weight by the temperature rising rate and the calculated decay heat. At least if the result has no sense we will know that there is something else happening inside.

 

[elektrownik]

What ? Unit 6 reactor building is floded ? How ?? I understand turbine building from tsunami, but reactor building ?
And 2m of water in unit 6 turbine building... But how, unit 5 turbine building is not so floaded like 6...



http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110531e19.pdf <- radiation data from unit 4 and 2 sfp

 

[tsutsuji]

What ? Unit 6 reactor building is floded ? How ?? I understand turbine building from tsunami, but reactor building ?
And 2m of water in unit 6 turbine building... But how, unit 5 turbine building is not so floaded like 6...

Yes, this is surprising. See also the discussion we had a few days ago :

Unit #6 is leaking also:

http://www.nisa.meti.go.jp/english/files/en20110519-1-2.pdf

Explanation #1: RPV is leaking.
Explanation #2: SFP is leaking.
Explanation #3: Waterproof systems are not working and groundwater is leaking into the reactor building.

The greatest danger lies in the explanation #3. If it's happening in the unit #6 it can also happen in the units #1 - #5. It water can come in it can also go out.

What about #4 : Unit 6 hit and flooded by a tsunami ?

The water levels have been rising in (5 and) 6.

The company says water levels are also rising in the Number 5 and 6 turbine buildings.

http://www3.nhk.or.jp/daily/english/21_03.html

 

[~kujala~]

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110531e19.pdf <- radiation data from unit 4 and 2 sfp

Thanks, it seems that they have again made corrections. This time to unit #4 and #2 SFP samples taken on April 12th and 16th. I am going here through #4 SFP values:

The original values were (April 12th):
I-131: 220 Bq/cm3 -> 220 000 Bq/l
Cs-134: 88 Bq/cm3 -> 88 000 Bq/l
cs-137: 93 Bq/cm3 -> 93 000 Bq/l

The corrected values are:
I-131: 130 000 Bq/l
Cs-134: 130 000 Bq/l
Cs-137: 140 000 Bq/l

The comparison of all samples taken in Bq/l:
Isotope: April 12th - April 29th - May 7th
I-131: 130 000 - 27 000 - 16 000
Cs-134: 130 000 - 49 000 - 56 000
Cs-137: 140 000 - 55 000 - 67 000

The values for Cs-134 and Cs-137 on May 7th are now 43 % and 48 % from the maximum values. I am eagerly waiting for them to take new samples from unit #4 SFP and also sample the unit #1 SFP.