Sunday, April 15, 2012

#Fukushima I Nuke Plant Reactor 2: Another Thermocouple on Pressure Vessel Dies

Another thermocouple goes kaput on the Reactor 2 Pressure Vessel.

From Jiji Tsushin (4/15/2012):

瞬時に6度上昇、異常と判断=2号機圧力容器温度計で-東電

Reactor 2 Pressure Vessel thermocouple deemed abnormal after jumping 6 degrees Celsius instantly, says TEPCO

 東京電力は15日、福島第1原発2号機圧力容器下部に設置された温度計が14日夜、瞬間的に6.1度の上昇を記録したと発表した。上がり方が異常だったため調査したところ、温度計の電流が流れにくくなっており信頼性に疑問が生じたと判断。15日未明に監視計器からは外すことを決めた。

TEPCO announced on April 15 that one of the thermocouples installed at the bottom of the Reactor 2 Pressure Vessel at Fukushima I Nuclear Power Plant jumped 6.1 degrees Celsius in an instant on April 14 night. TEPCO investigated, as the rise in temperature was abnormal. The resistance was found to be too high, and on early April 15 TEPCO decided to exclude the thermocouple from the list of instruments that are regularly monitored because there was a doubt on the reliability of the thermocouple.

 東電によると、異常とされた温度計は圧力容器底から高さ約2.9メートルの外壁に設置されており、14日午後9時ごろ突然、それまでの53.8度から59.9度に上昇した。同じ高さにある別の温度計では45度前後で大きな変化はなかった。

According to TEPCO, the thermocouple in question is installed on the outer wall of the Reactor Pressure Vessel, about 2.9 meters from the bottom of the RPV. At 9PM on April 14, the temperature suddenly jumped from 53.8 degrees Celsius to 59.9 degrees Celsius. The other thermocouple at the same height but at a different position stayed at about 45 degrees Celsius, showing no marked difference.

So, at this location, there will be only one thermocouple monitoring the temperature. Originally there were three, at the measurement location called "vessel wall above bottom head", but the first one, 69H1, died back in February after shooting up above 250 degrees Celsius. Now the second one has died, which must be 69H2, looking at TEPCO's temperature data on Reactor 2:

21 comments:

Anonymous said...

Amazing technology! I feel safe already.

Anonymous said...

Keep smiling ,don't worry be happy!

Hélios said...

I can see the new banner for your blog, Ultraman.

You let the picture of Ultraman, on the top, thanks.

elbows said...

They better hurry up with the mission to install new temperature measurement equipment, since it will be increasingly hard to claim stable cooling if there are few temperature measurements to back it up.

Anonymous said...

@elbows

no, no the less sensors or no sensor would be even better for claiming that stable cooling has been achieved. In Japan it is enough to BELIEVE, there is no need to back anything with evidence. The additional benefit of ZERO sensors is actually that the government officials and TEPCO can play the usual Japanese game - the three monkeys - really, I did not know , sorry.

Anonymous said...

Ok, one left. The real defective one ;) All other has been worked fine...

Anonymous said...

Russia Stunned After Japanese Plan To Evacuate 40 Million Revealed
Posted by EU Times on Apr 15th, 2012
http://www.eutimes.net/2012/04/russia-stunned-after-japanese-plan-to-evacuate-40-million-revealed/

misitu said...

Going back to the second endoscopy, it seems that there is still live core melt in the vessel. There are bubbles being released from the melt which implies a liquid covering. What I don't understand is that /further _down_/ the vessel there are no bubbles, rather what look like wisps of steam, which would suggest an atmospheric covering. How can we have water ABOVE a dry layer? this bothers me. I have to be mistaken.

There are also explosions, gamma overload, flare, rubble dispersing and settling, and broken material flowing downhill.

I've made some notes on a frame by frame chronology. What I need to do next is to clip the best bits out and upload where others can check them out, as the whole video is ages long and the first half wasted from being out of focus.

But if anyone wants to give this an eyeball and review in the meantime, feel free.

My analysis is that when Tepco say, "there's not much water covering the corium," they do not want you to think that there is no protection at all from corium in contact with atmosphere.

Cheers
Misitu

Anonymous said...

--------------------------------------------------
ANOTHER THERMOMETER BREAKS AT FUKUSHIMA, Kyodo News, via Japan Times Online, Sunday, April 15, 2012.[http://www.japantimes.co.jp/text/nn20120415x1.html]

~ One of the two remaining thermometers at the bottom of the pressure vessel of reactor No. 2 at the Fukushima power plant is broken, Tokyo Electric Power Co. said Sunday.

The finding follows the discovery of a broken thermometer in the same unit in February and means only 18 of its 36 temperature sensors are working, magnifying concerns about the utility's long-term ability to monitor the crippled facility.

Tepco said that the sensor's reading instantaneously jumped 6 degrees to hit 60 around 9 p.m. Saturday.

After checking the equipment, engineers found that the electric resistance of the device had greatly increased and concluded it was broken.

As of 11 a.m. Sunday, the reading of the only operational thermometer at the bottom of the reactor read 46.7 degrees, which is well below the "cold shutdown" threshold of 100 degrees, when water starts boiling and radioactive materials are released.

"We are able to check the temperatures at the vessel's bottom with the remaining one and assess whether a cold shutdown was being maintained by monitoring all the thermometers, including those at other locations," a Tepco spokesman said. ~

It doesn't appear Kyodo chose to remind readers that, in late March, 2012: "Cooling water at the plant's No. 2 reactor came up to just 2 feet from the bottom of the reactor's containment vessel [RPV]..That was far below the 10 meter-level (33 feet) estimated by officials when the government declared the plant stable in December...This raises fears that the broken-down remnants of the uranium fuel rods may not be completely submerged and in danger of heating up again". (Sourced from The New York Times)

This is what passes for "cold shutdown" these day. Yikes.

JP
--------------------------------------------------

Anonymous said...

Why do you need to be reminded by the mass media all the time that you say you don't trust, JP? Just stick with your favorite independent experts.

arevamirpal::laprimavera said...

@anon at 8:42AM, there is no such plan. It's only in the minds of non-Japanese speakers who read Mainichi Daily's erroneous translation of the original editorial and assumed if there was the "worst-case" scenario then the Japanese government must be acting upon it. It isn't.

Anonymous said...

Laprimavera, anybody - why would thermocouples at Reactor #2 be breaking? Anything about it in the press conferences or the news?

arevamirpal::laprimavera said...

All thermocouples on the RPVs were exposed to extremely high temperatures in the beginning of the accident, and many broke (or considered broken). TEPCO has been using the remaining ones with calibration, and I think Reactor 2 pressure vessel has the most thermocouples that are still more or less correctly measuring. I linked the report by TEPCO before, I'll go look for it again.

Karen Sherry Brackett said...

Also thermocouples routinely wear out too. They are supposed to be scheduled for replacements periodically to keep this information black out from happening under normal conditions. When it is desirous to have information black out those routine standard replacement procedures apparently are going out the window in Japan.

Anonymous said...

Brackett, if you think you can assist TEPCO in conducting routine standard replacement of thermocouples in 70-plus Sievert/Hr environment, go ahead, book your flight to Fukushima.

elbows said...

Indeed, what is becoming routine at Fukushima has very little to do with the established routines of the past.

I think the only person who has suggested humans enter containment was the disgruntled shareholder who invited TEPCO management to 'go inside the reactor and die'.

Anonymous said...

Yes, I'm sure that replacing thermocouples (I have no idea what they are but they sound cosy) was in their "RISK management" and "Worlds best practice" before the event.

It made no difference. They had an earthquake! It blew up! Just luck anything works now.

When's the next one?

Steve From Virginia said...

The thermocouple failure is not surprising. If anything happens with the core there will be 'other' warnings:

- steam flows in- and out of the building,

- increased hydrogen in gas sampling system,

- Xenon detected outside the reactor building.

There is a chance that Xenon poisoning is moderating the core material now.

- There needs to be neutron detectors installed in the reactor building.

Anonymous said...

http://www.physicsforums.com/showthread.php?t=480200&page=793

Anonymous said...

http://www.tepco.co.jp/en/news/110311/images/120322_11.jpg

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