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Japan Earthquake: nuclear plants

by gmax137
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tsutsuji
#12403
Feb23-12, 03:13 AM
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http://www.jiji.com/jc/c?g=soc_30&k=2012022300661 Thermometer "H2" on unit 2's RPV bottom rose by 11.5C in 24 hours reaching 47.8C at 11:00 AM on 23 February. However the other thermometer located at the same height rose by only 2C 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" 49.5C
"H3" 37.5C

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
#12404
Feb23-12, 11:38 AM
P: 361
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
#12405
Feb24-12, 12:27 AM
P: 30
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
#12406
Feb24-12, 07:31 AM
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http://www.47news.jp/47topics/e/225985.php Unit 2's thermometer that was rising, dropped by 4C to around 45C. However there is a 6C difference with the other thermometer at the same height, which displays between 38 and 39C. 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
#12407
Feb24-12, 12:15 PM
P: 361
Quote Quote by r-j View Post
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?
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
#12408
Feb24-12, 01:40 PM
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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
#12409
Feb24-12, 09:11 PM
P: 21
NRC Operation Center Fukushima Day 1 Transcripts Audio Clips

sorry dbl post link already posted
zapperzero
#12410
Feb25-12, 02:38 AM
P: 1,042
Quote Quote by Joffan View Post
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.
See also this post by TCups, from March 19.
http://physicsforums.com/showpost.ph...&postcount=536
zapperzero
#12411
Feb25-12, 03:09 AM
P: 1,042
Quote Quote by tsutsuji View Post
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 ]
This should clarify a lot about how and why the J-gov acted.

Here's one little story, in http://icanps.go.jp/eng/120224Honbun05Eng.pdf for example

In the meantime, on March 30, IAEA announced that the radiation dose level in
Iitate-mura had exceeded the IAEA criterion for evacuation, which corresponded to
100mSv for 7 days.The IAEA value, which exceeded its criteria was one data from one
point of total 9 points, was presented after converting the data measured by Japan to the
IAEA’s standard.
The inconsitency between Japan and IAEA happned even the same original data was
used. It might be caused by different criteria and method of judgement for evacuation.
IAEA criteria was based on a value of the ground surface density of radioactivity
(Bq/m2) which was derived by converting 100mSv for 7days, while Japanese criteria for evacuation is based on the radiation dose in the air. Moreover IAEA judged the necessity
of evacuation based on only one value above while Japan judged taking into account the
extended area of the radiation dose because only one one particular point data of higher
radiation dose in the air does not necessarily indicates a higher level of air dose in the
living space.
In addition, on April 1, the NSC determined that the air radiation dose rate was
decreasing day by day and that it might not be necessary to change the protective zone.
Subsequently, the NSC made an announcement to that effect.

(The IAEA criteria prescribes that the criterion for radioactive iodine 131 should be 10MBq/㎡. It was discovered
that the value that had been measured and converted at one particular point was an average value for the
concentration of radioactive iodine (Bq/kg) in the soil that had actually been measured between March 19 and 27,
that it was obtained by converting the surface concentration of radioactivity of radioactive iodine (Bq/㎡), and that
the value was approximately 20MBq/㎡)
zapperzero
#12412
Feb25-12, 03:28 AM
P: 1,042
also from http://icanps.go.jp/eng/120224Honbun05Eng.pdf

pp 319 and following
f. Establishment of specific spots recommended for evacuation

By April 22 when deliberate evacuation areas and emergency evacuation preparation
zones had been established, spots where annual cumulative radiation dose might exceed
20mSv assuming that the radiation dose levels continued afterwards had been found in
parts of Date-shi and Minami-soma-shi
. However, the distribution of these spots was not
understood for an extended area, but for a limited area. Hence, the Government
Emergency Response Center did not designate those entire areas including these points as
deliberate evacuation zones. Instead, they decided to take a wait-and-see approach
to
observe how radiation dose might decrease with time by monitoring them over time.
Subsequently, however, on June 3, MEXT estimated cumulative radiation dose and
found that there were spots where the estimated annual cumulative radiation dose for one
year after the nuclear accident might exceed 20mSv
of a criteria for deliberate evacuation
zones, in parts of Date-shi and Minami-soma-shi, which are located outside the deliberate
evacuation zone.
In response to this fact, the NERHQ discussed the adoption of concrete measures for
locations where spots with high radiation dose were found in some areas and created a
guideline referred to as "Response to specific spots estimated to exceed an integral level of
exposure of 20mSv over a one-year period after the accident." The guideline stated that
spots where the estimated annual cumulative radiation dose over a one-year period after
the nuclear accident might exceed 20mSv should be designated as "specific spots
recommended for evacuation," and that the NERHQ should notify all residents living in
these spots and assist and support their evacuation. On June 16, the Government
Emergency Response Center asked the NSC for its advice on this guideline. That same
day, the NSC responded to this request replying to the effect that it had no objection to the
Government Emergency Response Center' ideas, although it might be necessary to
consider possible ways to solve this problem without conducting an evacuation, including
finding ways to decontaminate the areas that were only partially contaminated with high
concentration of radioactive materials.
Based on this advice, the NERHQ decided that the spots where the estimated annual
cumulative radiation dose over a one-year period might exceed 20mSv should be
designated as specific spots recommended for evacuation.
That same day, Chief Cabinet
Secretary Edano released a statement to that effect.
It was decided that the NERLHQ should specify spots, per house, where
decontamination is not easy and are estimated to exceed 20mSv/year, through mutual
consultation between the Fukushima prefectural government and the cities, towns or
villages where those spots are located. Through mutual consultation with the respective
municipal governments, the NERLHQ designated parts of Date-shi on June 30 and
November 25, parts of Minami-soma-shi on July 21 and August 3, and parts of
Kawauchi-mura as specific spots recommended for evacuation.
Additionally, specific spots recommended for evacuation have not been issued with
evacuation orders
pursuant to the provisions of Article 20, Paragraph 3 of the Act on
Special Measures Concerning Nuclear Emergency Preparedness. This policy is based on
the idea that specific spots recommended for evacuation are not dangerous enough
to
instruct all residents to begin evacuation since radiation levels will be minimal if residents
leave the area, and that the government will provide information to alert them to the
possibility of radiation exposure and support residents if they need to be evacuated.
All formatting mine.
tsutsuji
#12413
Feb25-12, 05:41 AM
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The report seems to be too vague about the radiation levels in unit 1

After approximately 17:19 that day, the shift team decided to go to the 4th floor of Unit 1's R/B to check if a sufficient amount of water was contained or not in the IC condenser tank with a water level gage installed on the side of the tank. The shift team members who were sent to the building did not wear protective masks or protective clothes though they made other plans [had made preparations beforehand(1)] including a check of the gage location. They left the Units 1&2 main control room.When they arrived at the double doors of the R/B approximately 17:50 that day, they found that their dosimeter (GM tube) had gone beyond the maximum value of 300 cpm[29]. So, they abandoned their plan and returned to the Units 1&2 main control room.
http://icanps.go.jp/eng/120224Honbun04Eng.pdf page 124
(1) my translation
The above is quite precise with a measurement (albeit the measurement tool is out of scale). But a few pages further, the report only says :

The shift team decided to quickly make preparations for an alternative method of water injection and went into the R/B and T/B of Unit 1 at approximately 18:30 that day so as to configure a line for injecting water through the FP system to the reactor.
...
When the shift team went into the R/B of Unit 1 and measured the reactor pressure with a reactor pressure gage, the reactor pressure read 6.900 MPa at approximately 20:07 that day.
http://icanps.go.jp/eng/120224Honbun04Eng.pdf page 151
This time they enter the reactor building. Is it because the radiation had decreased ? Is it because they have their protective clothing on ? Or did they decide to enter anyway ? Or did they decide to enter through a different entrance ? If they could enter at that time, why did they not attempt to try again the IC checking mission they had given up at 17:50 ? Why do they give up so easily when the IC is concerned ?
tsutsuji
#12414
Feb25-12, 06:27 AM
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http://www.nikkei.com/news/category/...E09180EAE2E2E2 On 24 February, Tepco announced that 9 out of 41 unit 2 RPV thermometers are broken. The NISA instructed Tepco to write a report about this by 1 March. On 23 February, one of the unit 2 RPV thermometers had risen, but it is stable now.

http://mainichi.jp/select/biz/news/2...40102000c.html On 23 February, one of unit 2's RPV thermometers rose to 50.3C, but it dropped to 45.8 at 05:00 AM on 24 February. The NISA instructed Tepco to write a report by 1 March on the study of possibilities to use alternative means to measure reactor temperatures. As one of the three unit 2 RPV bottom thermometers started displaying abnormal values at the end of January, and was found to be broken, the RPV bottom is being surveyed by two thermometers.
jim hardy
#12415
Feb25-12, 06:35 PM
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This time they enter the reactor building. Is it because the radiation had decreased ? Is it because they have their protective clothing on ?
All i can offer is this speculation:
When they arrived at the double doors of the R/B approximately 17:50 that day, they found that their dosimeter (GM tube) had gone beyond the maximum value of 300 cpm[29]. So, they abandoned their plan and returned to the Units 1&2 main control room.
A GM tube is used only for very low radiation fields, it is useless in even a modest one.
Since that is what they were carrying they must not have expected radiation at the doorway to the building.
Proper procedure would be to return , notify shift supervisor of unecpectedly high field there.
They could have picked up high range instruments and returned, of course.

But if high radiation in that location told operators they needed to look at something else first, then that's what they would have done. I see attention being paid to fire pumps in those intervening pages, and flooded basements, but haven't digested the document yet.

It's a safe bet they were equipped with appropriate survey meters and coveralls and a new plan of action when they returned.

old jim
tsutsuji
#12416
Feb27-12, 11:51 AM
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http://www3.nhk.or.jp/news/genpatsu-...227/index.html [The 3rd mid-long term government-Tepco meeting] was held on 27 February. The multinuclide facility (the one which can remove strontium) will be introduced within the first half of 2012. Additional tanks for 40,000 tons of decontaminated water will bring the storage capacity to 200,000 tons by April. A new endoscope mission will take place in unit 2 during the last ten days of March, with a longer length, with the purpose of finding the PCV water level.

http://mainichi.jp/select/science/ne...40043000c.html According to the Ministry of Economy and Industry, recently the radiation released into the atmosphere by units 1,2,3 was 10 million Bq/hour, which is a decline from the 60 million Bq/hour estimated in December. Tepco tested multinuclide removal with 62 nuclides with a concentration 100 times lower than the legal level. At present 57 nuclides can be removed to below detection level. Using the multinuclide facility, it will become possible to bring the radiations below the legal level for releasing the water into the sea, but a Ministry of Economy and Industry official said "we are discussing with the local inhabitants etc. to decide whether we will actually do it".

http://www.meti.go.jp/committee/noti...120223001.html Notification of opening of 3rd mid-long term meeting


Workshop for technical catalog study regarding the development of equipment to remove fuel debris for decommissioning of Fukushima Daiichi Nuclear Power Station, 24 February, at Ministry of Economy and Industry main building in Tokyo :
http://www.meti.go.jp/earthquake/nuc...120227_01a.pdf Toshiba/Hitachi GE/Mitsubishi Heavy Industries : Main points of the public appeal of Technical catalog proposals
http://www.meti.go.jp/earthquake/nuc...120227_01c.pdf Agenda
http://www.meti.go.jp/earthquake/nuc...120227_01d.pdf Agency of Natural Resources and Energy : Technical catalog for equipments toward decommissioning of units 1,2,3,4.
http://www.meti.go.jp/earthquake/nuc...120227_01e.pdf (English) Tepco : Technical needs as viewed from the site
http://www.meti.go.jp/earthquake/nuc...120227_01f.pdf Toshiba/Hitachi GE/Mitsubishi Heavy Industries : Technical developments for remote decontamination inside reactor building
http://www.meti.go.jp/earthquake/nuc...120227_01g.pdf Toshiba/Hitachi GE/Mitsubishi Heavy Industries : Technical developments to find PCV leakage points [main features and picture of a Hitachi-GE underwater remotely operated vehicle are available on page 22/23]
http://www.meti.go.jp/earthquake/nuc...120227_01h.pdf Toshiba/Hitachi GE/Mitsubishi Heavy Industries : Technical developments to repair PCV
http://www.meti.go.jp/earthquake/nuc...120227_01j.pdf Toshiba/Hitachi GE/Mitsubishi Heavy Industries : Technical developments to inspect inside PCV
http://www.meti.go.jp/earthquake/nuc...120227_01k.pdf Vendor list (PCV inspection)
http://www.meti.go.jp/earthquake/nuc...120227_01m.pdf Technical catalog example
tsutsuji
#12417
Feb28-12, 11:10 AM
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http://www3.nhk.or.jp/news/genpatsu-...oukokusho.html The "independent fukushima accident investigation committee" has released its report after hearing 300 people such as former prime minister Kan and US high officials. The simultaneous occurrence of earthquake/tsunami with nuclear accident had not been foreseen so that the emergency manual was unusable. Politicians lacked basic knowledge of the legal framework. The response was haphazard and taken in haste at the last minute. Accurate information did not reach the prime minister office. The scientific support framework to advise politicians was too weak. The NISA is not educating safety professionals so that its human resources and ideas are poor. The NISA did not build plans and proposals. Tepco's responses (not being aware that IC is turned off, not starting alternative injection immediately, having troubles with venting) are causal factors of the widening of the accident.

http://www3.nhk.or.jp/news/genpatsu-...940_taiou.html According to the "independent fukushima accident investigation committee", prime minister Kan had some merits such as going to Tepco's main office to encourage Tepco not to evacuate (leaving 50 people on the site), but he interfered too much with the site when he managed such things as the size of batteries. His way of releasing information failed, causing distrust among citizens. Japan ignored suggestions that came from abroad after the September 11 attacks. The way of thinking was "as it is 100% safe, why bother to take countermeasures". The safety myth was designed as a tool against antinuclear activists, but it became an obstacle for the government itself, who failed from taking the latest safety knowledge and technology into account.

http://www3.nhk.or.jp/news/genpatsu-...10_speedi.html According to the "independent fukushima accident investigation committee", prime minister Kan and 4 politicians said "we did not receive information from the ministry of education and science about SPEEDI (the radiation spreading analysis system) until many days after the accident and ignored its existence until then". Yukio Edano said he heard about it for the first time in the news around 15 March. According to Edano, the reason why there was no information is because the SPEEDI results were thought to be too imprecise, as the radiation figures could not be obtained. According to the committee, SPEEDI was developed and installed as nothing but a trick to buy citizen's confidence.

http://rebuildjpn.org/wp/wp-content/...9c9d29885a.pdf Press release : The Rebuild Japan Initiative Foundation announces its accident investigation report.

http://rebuildjpn.org/news/998 We had free copies of the report, but we ran out of them after the press conference. We have received requests, but we are sorry not to be able to respond to them immediately. We are studying how to publish it at a cheap price or to make it available on the internet for the general public.
rmattila
#12418
Feb28-12, 11:52 AM
P: 242
The fact that loss of batteries may cause spurious fail-safe closure of valves in the pipe lines needed for core cooling in station black-out situations is in my view the single most important lesson that can so far be learnt from the Fukushima Daiichi accident. It was not known to the control room personnel of Tepco, but they can hardly be blamed, since this insight seems to be very rare even among the experts in the nuclear field and something certainly worth consideration at every NPP in the world.

As far as I've been able to find out, every BWR plant in the world with an IC - a really good and passive system to ensure the cooling of the reactor in station black out - depends on the battery-powered DC to keep the valves in this otherwise completely passive system opened. And in many cases, the batteries survive only a few hours of loss of AC, so the water reserves on the IC shell side might actually not play any role at all in the time the plant can survive a complete loss of AC.

I see design changes coming, after this issue (brought to attention largely by Tsutsuji-san's translations) becomes truly recognized. It doesn't help to have AC-independent emergency cooling systems, if the pipelines needed to get the water into the reactors can't be kept open in case of emergency.

The same fail-safe issue played a role in two other aspects of the Daiichi accident as well: pressure relief of the reactors and the containments was also prohibitively difficult after the power was gone, and thus reactors 2 and 3 were lost even though the capability to pump fire water existed at the time the RCICs failed.

So in my view, the more information we get, the more it starts to look that it was the loss of DC, not the loss of EDGs that was the fatal failure. And loss of DC is something the nuclear plants have (so far) generally not been designed to manage. I expect this will change in the future.
tsutsuji
#12419
Feb28-12, 12:06 PM
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Quote Quote by tsutsuji View Post
http://www3.nhk.or.jp/news/genpatsu-...227/index.html [The 3rd mid-long term government-Tepco meeting] was held on 27 February.
All the meeting's documents are now available at http://www.tepco.co.jp/nu/fukushima-...ference-j.html

http://www.tepco.co.jp/nu/fukushima-...20227_05-j.pdf
* Page 3/94 to 6/94 : PCV gas monitoring systems
* Page 7/94 to 10/94 : upcoming endoscope mission in unit 2. The figure on the bottom left of page 9/94 shows the endoscope going below the grating.
* Page 13/94 to 17/94 : plan to increase the reliability of the water treatment facility (adding pumps, lines, air compressor, etc.)
* Page 18/94 to 36/94 : multinuclide removal facility
* Page 37/94 to 46/94 : subdrain decontamination tests
* 47/94 to 52/94 : decontaminated water tanks replacements and increase
* 54/94 : management of debris
* 55/94 to 56/94 : start of harbour sea-floor covering work
* 57/94 to 58/94 : radiation releases from units 1,2,3 PCVs
* 59/94 : improvement of environment surrounding monitoring posts
* 62/94 to 69/94 : reduction of protective measures (mask charcoal filter versus dust filter etc.)
* 72/94 to 74/94 : reactor building debris removal at units 3 and 4
* 75/94 to 78/94 : survey toward debris removal from unit 4 fuel pool
* 79/94 to 85/94 : verification of unit 4 fuel pool integrity
* 86/94 to 90/94 : situation of unit 2 operating floor (with pictures of quince 2 and quince 3)

http://www.tepco.co.jp/nu/fukushima-...20227_10-j.pdf pictures of technical catalog workshop of 24 February on page 5/5
http://www.tepco.co.jp/nu/fukushima-...20227_12-j.pdf International symposium on decommissioning of Fukushima Daiichi to be held on 14 March 2012 in Tokyo.


http://www.tepco.co.jp/en/nu/fukushi...20228_04-e.pdf Feb 28, 2012 Investigation result by the robot (quince2) on the 5th operating floor of the Reactor Building of Unit 2
jim hardy
#12420
Feb28-12, 02:20 PM
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I heard on NPR a few minutes ago that tonight's PBS TV "Frontline" show will be on Fukushima reactors .


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