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Re: Japan Earthquake: nuclear plants - Temp sensors |
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May19-11, 02:15 AM
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#7809
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Posts: 46
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Re: Japan Earthquake: nuclear plants - Temp sensors
Originally Posted by pdObq
A few questions regarding the temperature sensors to figure out how trustable the temperature readings still are.
- Does anyone know what kind of temperature sensors they are using? (Thermocouple, resistive, semiconductor, ...)
- How is the sensor signal read out from the sensor to the control room? Are there amplifiers, AD converters, signal conditioning electronics and stuff like that located in the drywell close to the sensors?
- How are the sensors mounted at their various locations? (Thermally conductive glue?)
Is it conceivable that they can detach due to heat and humidity?
Concerning unit 1, if the sensors were just floating in the air, would it make sense that steam from the steamy atmosphere in there condenses on them and keeps them at roughly 100 degC ?
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1. Thermocouple.
2. Likely. The amplifiers are probably subject to high levels of radiation atm.
3. The sensors are mechanically connected to the pipes/vessel etc.
4. Possible.
Don't forget the sensors also where damaged when they subject to temperatures greatly exceeding their maximum rating. I don't believe the values they report now can be trusted with any certainty.
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May19-11, 02:22 AM
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#7810
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Posts: 46
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Re: Japan Earthquake: nuclear plants
Originally Posted by NUCENG
If they are adding water through the core spray lines the borescope would need to be able to go through a spray nozzle. If they go in through the RHR system they need to go through the Recirc system jet pumps. If they go in with RCIC or HPCI they would need to go through the feedwater header holes. They would have a long way to go after they get in to be able to get to the area below the core support plate. The most direct path would be through the jet pumps to the area of the lower plenum. All of these systems are in the lower level of the reactor building close to the torus in an extremely high radiation area.
A borescope expedition may be possible in spite of the difficulties. But here is the real question. Depending on what they see, what could they do differently than what they are already doing?
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You're not getting an image sensor anywhere near those high levels of radiation unless all you want to see is white noise.
That implies you have to snake the worlds longest fiber optic bundle through, valves, piping, debris into an environment that would bake said fiber bundle.
Nobody is going to look inside the RPV until radiation levels drop to the point that people can access the dry well.
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May19-11, 02:35 AM
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#7811
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Posts: 60
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Re: Japan Earthquake: nuclear plants
Originally Posted by zapperzero
Rejig how? Definite yes on the entry point, but since the connection they are using is outside the reactor building, I don't see that as a problem. Any pumps there may be are stopped, the whole jig is letting 9 cubic metres per hour through and I'm not sure I understand why there must be filters on that line. That may be just me being stupid, of course.
snip>.
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This is boring - Can we just leave this at the most obvious reason and the reason you didn't try and argue : they don't want to risk compromising the only cooling they have just to take an image of dubious usefulness inside the RPV? Thats more than a good enough reason to kill this discussion without getting too technical.
We could get into the piping complications of which there are potentially many but why bother, they are not going to try and send a borescope through that line. They will find a far more suitable entry point if\when they do try and image the inside of the RPV.
If you cannot see why there would very likely be filters on a water line leading into an RPV and you cannot understand why a borescope cannot get past most pump impellers, stationary or otherwise, then it's prob best to drop the idea.
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May19-11, 02:46 AM
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#7812
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Posts: 138
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Re: Japan Earthquake: nuclear plants
Originally Posted by Cire
You're not getting an image sensor anywhere near those high levels of radiation unless all you want to see is white noise.
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'Radiation hardened cameras' (google it) are available for nuclear industry. But Westfield is right, no use for such cameras now, they have to bring the reactors in cold shutdown first, and then secure everything before visually checking the internals of the containment/RPV. Such pictures will be needed only for the decommissioning, which will not happen in the next few years.
Originally Posted by NUCENG
Unit 5 Data is incomplete: no data from time of scram or time of tsunami. Data does show both EDGs started.
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It was on outage, so no SCRAM was needed?? :-)
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May19-11, 02:54 AM
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Last edited by MoonofA; May19-11 at 03:00 AM..
#7813
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Posts: 1
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Re: Japan Earthquake: nuclear plants
Originally Posted by Rive
'Radiation hardened cameras' (google it) are available for nuclear industry. But Westfield is right, no use for such cameras now, they have to bring the reactors in cold shutdown first, and then secure everything before visually checking the internals of the containment/RPV. Such pictures will be needed only for the decommissioning, which will not happen in the next few years.
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If there is an accessible 150mm line going into the drywell or reactor vessel this little machine would be the right thing to use.
http://www.khgmbh.de/wEnglisch/fernh...anchor=1010051
It was specially build for such purposes. These robots were offered by Germany to the Japanese at the start of this mess, but the offer was not taken.
I have copied parts from an image movie which shows the various nuclear accident robots Germany has for just such purpose. You can watch it here:
http://www.youtube.com/user/MoonofA#p/u/0/dbdwUnUvmFw
Edit: The French have similar equipment available on 24/7 standby
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May19-11, 03:20 AM
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#7814
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Posts: 522
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Re: Japan Earthquake: nuclear plants
Originally Posted by westfield
This is boring - Can we just leave this at the most obvious reason and the reason you didn't try and argue : they don't want to risk compromising the only cooling they have just to take an image of dubious usefulness inside the RPV? Thats more than a good enough reason to kill this discussion without getting too technical.
We could get into the piping complications of which there are potentially many but why bother, they are not going to try and send a borescope through that line. They will find a far more suitable entry point if\when they do try and image the inside of the RPV.
If you cannot see why there would very likely be filters on a water line leading into an RPV and you cannot understand why a borescope cannot get past most pump impellers, stationary or otherwise, then it's prob best to drop the idea.
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Yeah. Okay. I'm too stupid to understand an impeller pump, a bundle of fiber optic is just the kind of object you would use to plug a pipe shut, you have an opinion on whether there likely are filters and pumps on that line and it's way more valuable than mine because...
I can also see the usefulness argument. Who cares if there's still core in the RPV?
But yea, let's stop this here, the SNR is bad even without feelings getting in the way.
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May19-11, 03:22 AM
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#7815
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Posts: 205
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Re: Japan Earthquake: nuclear plants
Via the ek-skf site
From Yomiuri Shinbun (9:14PM JST 5/18/2011):
中部電力は18日、運転停止作業中に冷却水に海水が混入するトラブルが起きた浜岡原子力発電所(静岡県御前 崎市)5号機に隣接した補助建屋の排気ダクトの出口で、ごく微量の放射性核種「ヒ素76」を検出したことを 明らかにした。
Chubu Electric announced on May 18 that a minute amount of arsenic-76, radionuclide, was detected at the exhaust duct of the ancillary building to the Reactor 5 reactor building at Hamaoka Nuclear Power Plant, where the sea water got mixed up in the reactor coolant while the reactor was being shut down.
周辺環境への影響はないという。
The company says there is no ill effect on the environment.
同社は、トラブルの影響で、海水中に存在する「ヒ素75」が原子炉内で放射化したものとみて いる。
The company thinks arsenic-75 present in the seawater turned radioactive inside the reactor.
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May19-11, 03:26 AM
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#7816
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Posts: 650
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Re: Japan Earthquake: nuclear plants
Originally Posted by Rive
'Radiation hardened cameras' (google it) are available for nuclear industry. But Westfield is right, no use for such cameras now, they have to bring the reactors in cold shutdown first, and then secure everything before visually checking the internals of the containment/RPV. Such pictures will be needed only for the decommissioning, which will not happen in the next few years.
It was on outage, so no SCRAM was needed?? :-)
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You are right but I was looking for a SCRAM signal which should still have been generated and for the time the diesels tripped. Unfortunately in at least that data set the information is missing. I don't suspect a conspiracy here, They pulled this data together to meet government demands and I'm sure they didn't take their top people off there work to compile this data. The data includes photocopies of the recorder strip charts so I still may find the data I'm looking for on that site.
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May19-11, 03:54 AM
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#7817
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Posts: 121
Education: Graduate/Master's
Degree: Strategic security
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Re: Japan Earthquake: nuclear plants
Pictures from when the Tsunami hit Fukushima:
http://www.bt.dk/udland/her-rammer-t...m-kraftvaerket
A lot of new pictures I havent seen - shows the extent of the flooding
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May19-11, 03:58 AM
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#7818
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Posts: 650
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Re: Japan Earthquake: nuclear plants
Originally Posted by pdObq
On some pages it says "-99 = Missing control rod position". Don't know how to interpret that.
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Go to page 4 of that file. You see the Seismic Trip and SCRAM signals at 14:46:46 to 14:46:58. At 1447 you see All CR Full In. That signal requires all rods to be fully inserted.
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May19-11, 05:09 AM
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#7819
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Posts: 138
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Re: Japan Earthquake: nuclear plants
A half-off sidenote: http://www.technologyreview.com/blog/arxiv/26773/
Originally Posted by NUCENG
You are right but I was looking for a SCRAM signal which should still have been generated and for the time the diesels tripped.
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So the SCRAM signal should be there even if the reactor is not in active state. Interesting :-) Thanks.
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May19-11, 05:09 AM
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#7820
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Posts: 456
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Re: Japan Earthquake: nuclear plants
A few contaminated water management updates :
Instead of trying to move all the water as originally planned, TEPCO officials have decided to move only enough water so that it does not overflow from the trench.
(...)
TEPCO officials said work to install a temporary tank for the contaminated water by mid-July is continuing.
http://www.asahi.com/english/TKY201105180147.html
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Thanks. Some explanations about this picture release are provided by http://www3.nhk.or.jp/daily/english/19_24.html
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May19-11, 05:40 AM
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#7821
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Posts: 109
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Re: Japan Earthquake: nuclear plants
Unit #6 is leaking also:
Transferred stagnant water on the basement floor of the reactor building to
the Radioactive Waste Treatment
May 10th 11:00 ~ 12:30
May 11th 11:00 ~ 12:30
May 12th 10:30 ~ 12:30
May 13th 11:30 ~ 12:15
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http://www.nisa.meti.go.jp/english/f...110519-1-2.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.
Then I also noticed:
Why are they not updating the temperature/radiation/pressure charts?
For instance, the last one working for unit #3 (temperatures) is from 16th of May:
http://www.tepco.co.jp/nu/fukushima-...3_05160600.pdf
These ones are not working at the current moment (17th of May and 18th of May):
http://www.tepco.co.jp/nu/fukushima-...3_05170600.pdf
http://www.tepco.co.jp/nu/fukushima-...3_05180600.pdf
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May19-11, 06:49 AM
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Last edited by Borek; May19-11 at 07:17 AM..
#7823
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Posts: 45
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Re: Japan Earthquake: nuclear plants
Originally Posted by Gary7
Just regarding the USS Ronald Reagan, I looked for information regarding the ballistic radiation readings and subsequent food contamination and three-day emergency, but I could not find any. There was an early report of radioactivity in the drinking water, which was later shown to be a false positive. There is an excellent AP article that describes events on the Ronald Reagan here.
http://www.1310news.com/news/world/a...dex.php&title=
More details here
http://waronterrornews.typepad.com/h...an-update.html
Furthermore, all of this transpired on the 13th of March (Sunday). If I recall correctly, the explosion at Unit #3 occurred on Monday the 14th. So the radiation that the USS Ronald Reagan encountered had to have come from Unit #1.
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What transpired on the Reagan was a few hours after the explosion of #3, which happened on the morning of the 14th in Japan, which is the evening of the 13th in the United States.
If you don't believe me, find the records from UTC and we can translate. It's a fact, I listened to it, real-time. I'm not exactly sure why the hard core spin machine is moving to divert everything away from reactor #3, but whatever it is cannot be good.
The article you point out tells the story. I'm unable to now find the blogs from sailors who said the entire ship was near panic, but read between the lines in this story and you can tell:
http://www.1310news.com/news/world/a...dex.php&title=
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May19-11, 06:54 AM
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#7824
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Posts: 30
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Re: Japan Earthquake: nuclear plants
Originally Posted by tsutsuji
What about #4 : Unit 6 hit and flooded by a tsunami ?
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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
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