Japan Earthquake: nuclear plants

jim hardy

and indeed ZZ it's a voltage measurement.

zapperzero

You and me both. Out the window goes my neat little mental model.

A-ha. I hadn't seen that. It makes sense now. Thanks.

tsutsuji

Page 21 is an experiment they made by connecting a variable resistor in series in one of the wires. When they set the resistor at 1.2 kΩ a small oscillation takes place and at 8 kΩ they find a large oscillation. The water's temperature is controlled by the reference thermometer (black curve) : 59°C for the 1.2 kΩ experiment, and 100°C for the 8 kΩ experiment.

They call these variations "hunching" (?) in English.

On pages 22 and 23 they make another experiment, by simulating cable damage, stripping the cable's insulator, leaving only one strand of copper on the copper wire, connecting a 40 kΩ resistor, and using salt water.

The resistance measurement results on unit 2's thermometers are in the table at the bottom of page 8 (copied also in the table page 15) :

30 september 2011 : 175.47 Ω (low insulation)
3 February 2012 : 244.25 Ω (low insulation)
13 February 2012 : from 500 to 523 Ω (rupture)
Average value of regular inspections : 303.37 Ω

They say that as a rule when the ratio of ( measured resistance / average regular inspection value ) is higher than 1.1, it means that the wire is in a rupture trend. It seems also that when this ratio is smaller than 1 they conclude "low insulation" in the table page 8.

At paragraph d) on page 18, which is the last sentence of the part of the report concerning the causes of the problem (following pages are attachments), they tell about their plans for the future : to verify the consistency between the experiments and the real phenomenon and to elucidate how the problem was generated.

The last part of the report, from page 36 to the end is about the different approaches that can be thought to perform alternative temperature measurements. They are listed in the table page 38. The schedule is on page 39.

jim hardy

Thanks Tsujitsu

I guess i shoulda kept quiet - all i could see was the pictures..
I hope i didnt mis-lead severely, thought that was plant data. I apologize.

Unbalance in the leads can upset low level measurement systems.

They are becoming the world experts at thermocouple failure interpretation...

Thank you again for your hard work at finding and posting this information.



old jim

rmattila

Tsutsuji-san is truly doing a remarkable effort in helping many people to get an ever-improving picture of the events that took place and the current status of the plants. I have no doubt in my mind that some of this information will eventually lead into actual improvement of nuclear safety in many existing plants, as well as in those built in the future. With persistence and devotion, one man can really make a difference.

Thank you for not giving up!

NUCENG

An additional consideration is the effect of radiation (beta and gamma) on the instrumentation cables insulation and cable jackets. Over time I would expect more of the thermocouple cables to have insulation degradation and develop problems. These instruments were not required to be qualified as BWR post-accident monitoring instruments in US plants under RG 1.97. That may be changing.

tsutsuji

http://www3.nhk.or.jp/news/genpatsu-...217/index.html Tepco will reduce unit 2's injection rate by 4 tons/hour on 18 February.

http://www3.nhk.or.jp/news/genpatsu-...218/index.html The cause of the collapse of the Yonomori line tower No. 27 was underground water. The tower collapsed 2 minutes 30 seconds after the start of the earthquake. Underground water flows under the embankment. The ground became weaker as a consequence of shaking for a long time. The embankment was constructed during the 1965 - 1975 period to fill up a marsh, so there is much water. Tepco checked 530 towers concerning the Fukushima Daini and Kashiwazaki Kariwa plants, etc. but found no similar case.

http://www.tepco.co.jp/cc/press/betu...es/120217c.pdf "causes of damage situation of power facilities inside and outside of Fukushima Daiichi Nuclear Power" (2nd release) (Japanese, 15 pages)

http://www.tepco.co.jp/cc/press/betu...es/120217b.pdf "safety evaluation of transmission tower foundations regarding the offsite power supply to nuclear power stations and reprocessing plants" (Japanese, 17 pages)

tsutsuji

http://www.yomiuri.co.jp/e-japan/chi...OYT8T00073.htm Robots Quince No.2 and No. 3　were dispatched from Chiba Institute of Technology to Fukushima Daiichi on 20 February. They are equipped with a cutter so that they can cut their cable to free themselves in case the cable is entangled. Quince No.2 has a camera arm long enough to look over the fuel pool fence, which Quince No.1 could not do.

LabratSR

Nuclear Regulatory Commission releases audio of Fukushima disaster

http://www.marketplace.org/topics/wo...shima-disaster



About 3000 pages of transcripts

http://pbadupws.nrc.gov/docs/ML1205/ML120520264.html

Audio
http://youtu.be/ciRRsCIAy6A

tsutsuji

http://www.jiji.com/jc/c?g=soc_30&k=2012022300661 Thermometer "H2" on unit 2's RPV bottom rose by 11.5°C in 24 hours reaching 47.8°C at 11:00 AM on 23 February. However the other thermometer located at the same height rose by only 2°C during that time.

http://www.jiji.com/jc/c?g=soc_30&k=2012022300661 Unit 2 RPV bottom temperatures on 23 February, 17:00 :
"H1" (broken)
"H2" 49.5°C
"H3" 37.5°C

If "H2" alone continues to rise, there will be a suspicion that it is broken. The situation will be surveyed for the coming 2 or 3 days.

Joffan

This is after reducing the cooling water flow back down again, right? So some rise is expected, but not sudden shifts. There have been glitches in the past wher the readings have suddenly flipped to a new value, though, which looks like instrumentation rather than reality. http://atmc.jp/plant/temperature/?n=2

r-j

On page 232 of the transcripts they are talking about "the lifting of the flange on the drywell", at 65 pounds pressure. What does that mean?

The drywell head, the bolted flange, it might be lifting from pressure, causing the pressure in the containment to rise. Are they talking about the top of the reactor? Or the containment?

tsutsuji

http://www.47news.jp/47topics/e/225985.php Unit 2's thermometer that was rising, dropped by 4°C to around 45°C. However there is a 6°C difference with the other thermometer at the same height, which displays between 38 and 39°C. Either it is a consequence of the dispersion of the meltdown fuel or one of the two thermometers has a defect.

http://www.tepco.co.jp/en/nu/fukushi...20224_05-e.pdf "Temperature of the RPV Bottom at Unit 2, Fukushima Daiichi (1F) NPS"

Joffan

I think they're speculating that the containment lid lifted off its seals at that containment pressure (venting gas into the building), resealing when pressure dropped.

The operating pressure in the reactor vessel is routinely a great deal higher than 65psi.

tsutsuji

http://icanps.go.jp/eng/interim-report.html Full English translation of Cabinet Investigation Committee Interim Report (26 December 2011) [I had translated a few parts of the same document at http://www.physicsforums.com/showpos...ostcount=12105 ]

http://www3.nhk.or.jp/news/genpatsu-...15_rousai.html The 60 year old worker who died in Fukushima Daiichi in May was recognised by the Labor Standards Inspection Office as a case of "workmen's accident", saying that "the cause is excessively heavy work under the unfree condition where one wears a protective clothing and a mask".

http://www3.nhk.or.jp/news/genpatsu-...1950_robo.html Tepco is studying the use of underwater robots in order to inspect the containment vessels. After opening a hole in the floor of the reactor building's first floor, the robot would be put into the accumulated water in the basement. The robot would be able to inspect the containment vessel's bottom and to perform repairs. As the start of the removal of fuel debris is scheduled within 10 years, the progress in the development of the necessary techniques is a key question.

http://www3.nhk.or.jp/news/genpatsu-...224/index.html The result of the NISA's onsite inspection from 6 February to 24 February is that the safety measures are "by and large suitable", although a few unsufficient responses were found, such as not writing down the necessary notifications when injection rates were changed at unit 2.

Lambert

NRC Operation Center Fukushima Day 1 Transcripts Audio Clips

sorry dbl post link already posted

zapperzero

See also this post by TCups, from March 19.
http://physicsforums.com/showpost.ph...&postcount=536