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Japan Earthquake: nuclear plants

by gmax137
Tags: earthquake, japan, nuclear
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Barneysee
#10639
Jul15-11, 04:23 PM
P: 6
Quote Quote by swl View Post
Does this mean that they have now evacuated an additional 100 cubic meters of contaminated gas from the reactor?
LOL
Quote Quote by swl View Post
is hydrogen production likely to remain problematic?
It probably remains a possibility that an OX/H reaction could still go bang ala unit 2. If it did, TEPCO would sure look foolish.

I think I would be pumping nitrogen too if I were them.
joewein
#10640
Jul15-11, 08:34 PM
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P: 192
Quote Quote by swl View Post
is hydrogen production likely to remain problematic? As far as I can tell, there should be little trouble of hydrogen collecting within the reactor 3 building. Are they just trying to keep oxygen out of the (mostly empty?) RPV?
The talk about nitrogen injection started as soon as they got cooling water flow going again and especially after they formulated their plan of bringing all three reactors to "cold shutdown" (whatever that means for reactors as wrecked as that). If the temperature drops below boiling, as per definition of cold shutdown, then there is no steam pressure that would keep external oxygen out, so they were concerned about any lingering hydrogen from the zirconium reaction mixing with air, with the containments having lost air tightness. If the cooling water condensates steam in the containment, it could create a vacuum that sucks in air.

I am not sure how much of that hydrogen could be left by now. A lot of cooling water must have boiled into steam and displaced hydrogen, diluting it further and further.

On the other hand, as long as there are both high levels of radioactivity and water in the plant, hydrogen + oxygen production of from radiolysis of water remains possible, especially if it's hot enough (at least in places) for the gases to escape with steam from boiling liquid before they have a chance of recombining.

Injecting nitrogen is the safe thing to do if you can't be sure about how much hydrogen is remaining or is yet to be produced from radiation.
tsutsuji
#10641
Jul15-11, 11:20 PM
PF Gold
P: 1,220
http://news.xinhuanet.com/english201...c_13988710.htm "Japan's Kansai Electric Power Co. said on Saturday it planned to manually shut down the No.1 reactor at its Ohi nuclear power plant in western Japan's Fukui Prefecture due to technical glitches with its cooling system"

http://sankei.jp.msn.com/affairs/new...2160010-n1.htm Tepco announced the safety measures against the Typhoon No. 6 at Fukushima Daiichi. The megafloat filling operation will be stopped. Big swell being expected, hoses will be removed and equipments will be tightened with ropes. Roof sheets will be installed on turbine buildings, and sandbags will be installed around buildings to stop rain water.

http://www3.nhk.or.jp/news/html/2011...253181000.html Tepco has announced its plans for the July 2011 - January 2012 "step 2" of the roadmap. It was not expected to go beyond studying a ground water shielding wall, but it was decided to step up the pace and to start building the wall as part of "step 2". It is also planning improvements at the water treatment facility such as shortening or reinforcing the 4 km long pipes. A middle term schedule will be announced on 19 July. It is already known that the building of solid containment structures for reactors and the removal of fuel from the spent fuel pools will take about 3 years.

http://sankei.jp.msn.com/affairs/new...1560009-n1.htm Two reasons are suspected for the decrease of the water treatment facility flow rate to 37 ton/hour instead of the expected 50 ton/hour : air trapped in pipes and foreign bodies. After bleeding air from pipes yesterday, the flow increased to 39 ton/ hour. Tepco keeps investigating.

http://www.tepco.co.jp/en/nu/fukushi...10716_01-e.pdf Diagrams showing "Countermeasures against Decline in Flow Rate".
Bandit127
#10642
Jul16-11, 01:34 PM
P: 189
A new video (18.2 Mb) is available from Tepco's site from a 'quince' robot in Unit 2.

Towards the bottom of the video are windowed video feeds:
Left pane = wide angle overhead view of the robot.
Centre pane = rear facing
Right pane = front facing

At the top are some other bits & pieces, including temperature (centre). I don't know if the 2nd from the left is radiation, temperature, or what.

http://www.tepco.co.jp/en/news/11031.../110716_01.zip
tsutsuji
#10643
Jul16-11, 04:02 PM
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P: 1,220
http://elpub.wdcb.ru/journals/rjes/v...11ES000503.pdf (I.N. Tikhonov, "2011 Mega-earthquake on 11 March 2011 in Japan and aftershock process dynamics' development", Russian Journal of Earth Sciences, written in April 2011, published in May 2011) Choosing to focus on the earthquakes with a magnitude greater than 7.6, this article provides on page 4 two simple maps of the historical seismic data in North-East Japan in support of the view that "the existence of a seismic gap at the length of ~ 800 km was retrospectively revealed, located to the south of 39N and filled recently with aftershocks of the mega-earthquake".

Quote Quote by Bandit127 View Post
Left pane = wide angle overhead view of the robot.
There is also a small screen below that one. It is marked with 水位計リール "water level gauge reel".

Quote Quote by Bandit127 View Post
I don't know if the 2nd from the left is radiation, temperature, or what.
The word "dose" can be read. The figures are consistent with the values in milisievert/hour provided at http://www.tepco.co.jp/en/nu/fukushi...10711_04-e.pdf which also maps the robot trajectory inside the reactor building.

The analysis of the air samples taken by the robot are available on http://www.tepco.co.jp/en/nu/fukushi...10711_03-e.pdf . It shows that the air can't be breathed.

A video showing the outer view of quince during a test was provided in June : http://www.tepco.co.jp/en/news/11031.../110620_25.zip (4.6 Mb).
Bandit127
#10644
Jul16-11, 05:03 PM
P: 189
Quote Quote by tsutsuji View Post
http://elpub.wdcb.ru/journals/rjes/v...11ES000503.pdf (I.N. Tikhonov, "2011 Mega-earthquake on 11 March 2011 in Japan and aftershock process dynamics' development", Russian Journal of Earth Sciences, written in April 2011, published in May 2011) Choosing to focus on the earthquakes with a magnitude greater than 7.6, this article provides on page 4 two simple maps of the historical seismic data in North-East Japan in support of the view that "the existence of a seismic gap at the length of ~ 800 km was retrospectively revealed, located to the south of 39N and filled recently with aftershocks of the mega-earthquake".



There is also a small screen below that one. It is marked with 水位計リール "water level gauge reel".



The word "dose" can be read. The figures are consistent with the values in milisievert/hour provided at http://www.tepco.co.jp/en/nu/fukushi...10711_04-e.pdf which also maps the robot trajectory inside the reactor building.

A video showing the outer view of quince during a test was provided in June : http://www.tepco.co.jp/en/news/11031.../110620_25.zip (4.6 Mb).
I have to use Google and I hope it makes sense.

我々の知識への貢献は、測定を超えた価値を持っていま

Thank you Tsutsuji for all your posts.

Jim
Atomfritz
#10645
Jul16-11, 06:40 PM
P: 74
Quote Quote by joewein View Post
The talk about nitrogen injection started as soon as they got cooling water flow going again and especially after they formulated their plan of bringing all three reactors to "cold shutdown" (whatever that means for reactors as wrecked as that). If the temperature drops below boiling, as per definition of cold shutdown, then there is no steam pressure that would keep external oxygen out, so they were concerned about any lingering hydrogen from the zirconium reaction mixing with air, with the containments having lost air tightness. If the cooling water condensates steam in the containment, it could create a vacuum that sucks in air.

I am not sure how much of that hydrogen could be left by now. A lot of cooling water must have boiled into steam and displaced hydrogen, diluting it further and further.

On the other hand, as long as there are both high levels of radioactivity and water in the plant, hydrogen + oxygen production of from radiolysis of water remains possible, especially if it's hot enough (at least in places) for the gases to escape with steam from boiling liquid before they have a chance of recombining.

Injecting nitrogen is the safe thing to do if you can't be sure about how much hydrogen is remaining or is yet to be produced from radiation.
There was already much sub-atmospheric pressure. Just see Jorge Stolfi's great diagrams.
To me it looks not much different from that what happens when you let a kettle with a bit of water cool down after boiling.
In fact this makes me somewhat optimistic that there is probably no big danger of melt-through. Tepco probably just wants to make sure that there is insufficient oxygen so that the reactors don't poop again.

Quote Quote by tsutsuji View Post
http://news.xinhuanet.com/english201...c_13988710.htm "Japan's Kansai Electric Power Co. said on Saturday it planned to manually shut down the No.1 reactor at its Ohi nuclear power plant in western Japan's Fukui Prefecture due to technical glitches with its cooling system"
German Spiegel says that it has been shut down because the emergency boron injection system has been found to have too little pressure. Dunno what is correct.

Quote Quote by tsutsuji View Post
url]http://sankei.jp.msn.com/affairs/news/110716/dst11071612160010-n1.htm[/url] Tepco announced the safety measures against the Typhoon No. 6 at Fukushima Daiichi. The megafloat filling operation will be stopped. Big swell being expected, hoses will be removed and equipments will be tightened with ropes. Roof sheets will be installed on turbine buildings, and sandbags will be installed around buildings to stop rain water.
Sand bags just for rain?!? Sounds more like some flooding. How much liters per sq.m. is normal in Japan?!?

Quote Quote by tsutsuji;3405736[url
http://sankei.jp.msn.com/affairs/news/110716/dst11071611560009-n1.htm[/url] Two reasons are suspected for the decrease of the water treatment facility flow rate to 37 ton/hour instead of the expected 50 ton/hour : air trapped in pipes and foreign bodies. After bleeding air from pipes yesterday, the flow increased to 39 ton/ hour. Tepco keeps investigating.
Just my 2 ct.: When scaling up from liters (La Hague) to cubic meters (Fukushima Daiichi) they forgot to include "Luftabscheider" (don't know english word, sorry. These devices keep tubes and such free from air and gases, preventing them from clogging. Can anyone please tell how this is called in english? -thanks!)
Barneysee
#10646
Jul16-11, 07:19 PM
P: 6
Deaerator (removes the air)
joewein
#10647
Jul16-11, 10:08 PM
joewein's Avatar
P: 192
Quote Quote by Atomfritz View Post
Sand bags just for rain?!? Sounds more like some flooding. How much liters per sq.m. is normal in Japan?!?
Here's a rainfall map from a typhoon two months ago:

http://www.nasa.gov/images/content/5...-TRMM_full.jpg

As you can see, some areas got in excess of 100 mm during that one storm (i.e. 100 l per m2), two months' worth of rainfall in Germany. Landslides during typhoons are quite common in Japan.
turi
#10648
Jul17-11, 04:02 PM
P: 46
- At 11:40 am on July 17, the Clean up Water System of Unit 2 has been
restored.
* Clean up Water System (CUW): system to remove impurities in reactor
water and maintain the water quality; The system is also used to
control reactor water level by discharging redundant water from the
reactor during a regular inspection or reactor shutdown.
http://www.tepco.co.jp/en/press/corp...1071708-e.html
Interesting. Is the Clean up Water System now being used for the spent fuel pond? I can't really see them using it for cooling the reactor as such.
Atomfritz
#10649
Jul17-11, 05:33 PM
P: 74
Thanks all for the info!
Quote Quote by joewein View Post
...in excess of 100 mm during that one storm (i.e. 100 l per m2)
This really worries me.
At least, if there such "rains" are regular, I no longer wonder why the roof of Unit 3 so quickly looked like having been cleaned with a big water hose.
I could imagine if such masses of water are going to splash down through the staircases into the lower floors, the radiation measures done recently could be obsolete soon again.


(image taken from this Tepco pdf)

I am really surprised of this sudden "appearance" of a roof for Unit 3.
Is Tepco ahead of their "official" roadmap, or did they just realize that they do not want big rainwater streams in the reactor buildings?
Attached Thumbnails
appearanceroof.JPG  
Caniche
#10650
Jul17-11, 05:46 PM
P: 106
Quote Quote by Atomfritz View Post

(image taken from this Tepco pdf)
Very comforting ,all neat and tidy no detritus not even a stray roof spar. Bit worried about the lack of blue goo that keeps down the wind blown poison though, thought they'd sprayed all over the site a dozen times just to be sure.Maybe its a projected image like estate agents use
tsutsuji
#10651
Jul18-11, 04:26 AM
PF Gold
P: 1,220
Quote Quote by Atomfritz View Post

I am really surprised of this sudden "appearance" of a roof for Unit 3.
Is Tepco ahead of their "official" roadmap, or did they just realize that they do not want big rainwater streams in the reactor buildings?
I think Tepco is merely showing the roof sheets before installing them on a roof, saying the sheets on the picture are intended for unit 3.

Judging by the greenish color of the reactor building in the background, this must be reactor No.5 or No. 6. (You can compare the bluish color of reactors 1~4 with the greenish color of reactors 5~6 on http://cryptome.org/eyeball/daiichi-npp2/pict55.jpg ). I think the background of http://www.tepco.co.jp/en/news/11031...s/110717_1.jpg (or http://www.tepco.co.jp/en/nu/fukushi...10717_01-e.pdf ) is, from left to right : the Futaba and Yonomori power lines, unit 5 reactor building and unit 5 turbine building.

The rain from typhoon 6 has not started pouring. If typhoon 6 ever comes to Fukushima, it will be after it reaches Tokyo, and it is not expected in Tokyo before July 20th : see http://www3.nhk.or.jp/news/html/2011...272451000.html

Quote Quote by turi View Post
http://www.tepco.co.jp/en/press/corp...1071708-e.html
Interesting. Is the Clean up Water System now being used for the spent fuel pond? I can't really see them using it for cooling the reactor as such.
This news is about the other plant, Fukushima Daini, located a few kilometers south from Fukushima Daiichi.
turi
#10652
Jul18-11, 04:34 AM
P: 46
Quote Quote by tsutsuji View Post
"Interesting. Is the Clean up Water System now being used for the spent fuel pond? I can't really see them using it for cooling the reactor as such."
This news is about the other plant, Fukushima Daini, located a few kilometers south from Fukushima Daiichi.
Right. Sorry for the mixup. And thanks for all your posts, they're very informative.
Gary7
#10653
Jul18-11, 04:37 AM
P: 75
Regarding the "roof", the Tepco press release for today says:

As precaution against rain for the exposed top section of the turbine building for Reactor #3, construction of a temporary roof was begun at 8:30am (July 18th).

(original Japanese) 7月18 日午前8時30 分、3号機タービン建屋屋上開口部の雨水対策として仮屋根の取り付け作業を開始しました。

Also mentions a worker who was injured in a fall from an electric pole/pylon today, and was transported to hospital via helicopter.

http://www.tepco.co.jp/nu/f1-np/pres...a/bi1632-j.pdf
tsutsuji
#10654
Jul18-11, 04:44 AM
PF Gold
P: 1,220
I think both are correct :

The functions of the ECCS accumulators are to supply water to the
reactor vessel during the blowdown phase of a loss of coolant accident
(LOCA), to provide inventory to help accomplish the refill phase that
follows thereafter, and to provide Reactor Coolant System (RCS) makeup
for a small break LOCA.
(...)
The accumulators are pressure vessels partially filled with borated water
and pressurized with nitrogen gas.
http://pbadupws.nrc.gov/docs/ML0916/ML091671716.pdf
See also the diagram released by Kepko showing the accumulator that broke down at Ohi NPP : http://www.kepco.co.jp/pressre/2011/...0716_1j_01.pdf (ぼう酸水=borated water ; 窒素=nitrogen ; 弁=valve ; 蓄圧タンク= accumulator ; 水位計=water level gauge ; 圧力計=pressure gauge)

Here is Kepko's 16 July press release :

About the manual shutdown of Ohi NPP unit 1 (decline of pressure at accumulator C)

Ohi NPP unit 1 (pressurized water reactor, nominal output 1,175,000 kW, nominal thermal power 3,423,000 kW) was undergoing a test run as part of inspection No.24 when the "high/low pressure, accumulator※ C" alarm was issued, at 10:46 PM, 15 July 2011.

When we checked the pressure gauge, instead of the normal 4.60 MPa, the pressure was 3.65 MPa, which is below the safety limit of 4.04 MPa. For this reason, we started bringing nitrogen using the nitrogen supply line at 11:20 PM and at 11:45 PM the pressure had risen back to 4.09 MPa, satisfying the 4.04 safety standard.

The supply of nitrogen was completed at 12:38 AM, today, and a visual inspection of the accumulator and nearby valves was undertaken, but no abnormality was observed. The pressure was stabilized at 4.08 MPa.

As we prioritize safety, in order to inspect the causes of the pressure decline and to implement countermeasures, we decided to start decreasing the output at around 1 PM today, and at around 9 PM we shut down the reactor.

This event is not causing radiological consequence to the environment.

※ Accumulator : Accumulators are tanks storing borated water. Each of the 4 primary cooling systems is installed with one. During a loss of coolant or other accident, when the pressure in a primary cooling system drops lower than the pressure of the nitrogen-pressurized accumulator, borated water flows into that primary cooling system.


About the manual shutdown of Ohi NPP unit 1 :
http://www.kepco.co.jp/pressre/2011/...0716_1j_01.pdf (pdf 28.6 KB)

Source : http://www.kepco.co.jp/pressre/2011/0716-1j.html (my translation)
About Fukushima Daiichi NPP :

http://www.yomiuri.co.jp/science/new...OYT1T00495.htm there is more than one hole in the roof of unit 3 turbine building. The largest is 14 x 11 m wide. The repair is made with 3 steel sheets of 5 x 16 m each. While this repair is done today, the other holes will be repaired tomorrow. What is feared is that if too much rain water pours through the holes, the water accumulated in the turbine building might overflow and leak into the sea.

http://www.asahi.com/special/10005/TKY201107170417.html this is an assessment of the "step 1" of the roadmap. The following are marked with the "〇" (completed) symbol :

〇 closed loop reactor cooling
〇 starting the water treatment facility
〇 nitrogen injection
〇 SFP cooling (implemented in advance at units 2 & 3)

Then we have the "△" (under execution) symbol

△ reinforcement of unit 4 against earthquakes
△ hyperthermia prevention
△ assessment of the radiological status of the environment
△ removing debris

Then the "" (execution impossible)

repair the containment vessels (the locations of the damages are not even known)

It is expected that the government will announce tomorrow that they will start to study the lifting of some of the evacuation-prepared areas, based on the prerequisite that the nitrogen injection prevents hydrogen explosions and that new radiological emissions are curbed at a low level.

http://www3.nhk.or.jp/news/genpatsu-...5_suiryou.html On 17 July afternoon, Tepco changed the pump that injects water into both unit 1 and unit 2 reactors. Its maximum flow rate is 20 m/hour. On the morning of 17 July, the flow rate injected into unit 1 declined to about 3 m/hour instead of the expected 3.8 m/hour, ringing an alarm. The flow rate had to be ajusted again to 3.8 m/hour. While nothing similar happened on the unit 2 line, it is the third time this sort of trouble happens at unit 1. For that reason it is believed that there is dirt in the piping to unit 1.
Joe Neubarth
#10655
Jul18-11, 03:58 PM
P: 238
Iodine 131 Four months after Reactor Three Blew???? One hundred and twenty some days after Reactor Three Building blew, and they are still finding I-131 ?????????

This is very frightening. As previously stated, Iodine-131 being very radioactive has a rapid half life. Every week or so half of it is gone. After 80 days it should be almost impossible to detect. Yet, here we are FOUR months after the BIG Detonation of Reactor Three and we are still seeing large amounts of Iodine 131 in water samples.

Am I wrong or should this not be happening???

Tokyo govt finds iodine-131 levels up to quadruple cesium levels in water reclamation centers.
July 18th, 2011 at 07:35 AM


Measurements of radioactivity in sewage treatment, etc., Sewer Authority (Tokyo), July 15, 2011:
http://translate.google.com/translat...i/infn0533.htm
robinson
#10656
Jul18-11, 04:02 PM
P: 201
It may mean the amount of Iodine that was released was far higher than was reported.


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