Japan Earthquake: nuclear plants

zapperzero

Quote by 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 ]

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

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

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

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 50.3°C, 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

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

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

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

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

Quote by tsutsuji

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

I heard on NPR a few minutes ago that tonight's PBS TV "Frontline" show will be on Fukushima reactors .

NUCENG

Quote by jim hardy

I heard on NPR a few minutes ago that tonight's PBS TV "Frontline" show will be on Fukushima reactors .

Thanks Jim. I am in a hotel which doesn't have PBS channel. The Frontline story will also be available online at
http://www.pbs.org/wgbh/pages/frontline/view/

tsutsuji

Quote by tsutsuji

http://www.tepco.co.jp/nu/fukushima-...20227_05-j.pdf
* 79/94 to 85/94 : verification of unit 4 fuel pool integrity

On page 85/94 there are four measurements of the distance between the reactor well water level and the 5th floor's floor in four locations. The measurements show that the floor is horizontal. It looks like the old "unit 4 is leaning" theory is ruled out...

Jim Lagerfeld

Since the no fly zone was reduced to 3km on Feb 25th, there has been a lot of fresh aerial news helicopter footage of the plant site run on Japanese TV. Someone has uploaded one of the clearest clips to youtube:

http://www.youtube.com/watch?v=1Vq5T...layer_embedded

The presenter sounds particularly surprised by the complete mess which still obscures the spent fuel pool in reactor 3 (from about 1min20s).

I was more surprised by the extent of the new tank farms and waste storage.

tsutsuji

Also if you compare with the pictures taken in March 2011 (for example those on http://pinktentacle.com/2011/04/high...shima-daiichi/ ) it is clear that they have removed most of unit 4's roof.

NUCENG

Quote by jim hardy

I heard on NPR a few minutes ago that tonight's PBS TV "Frontline" show will be on Fukushima reactors .

I was impressed with the documentary on Frontline. There was little or no technical content. There was no judgement of pro or anti nuclear position. There was instead an excellent cross section of the human story of the immediate consequences of the Earthquake/Tsunami/Nuclear Accident. The nuclear director of TEPCO and the former Prime Minister described some of the decisions they made. The fisherman who saved his boat but lost a wife and daughter to the tsunami spoke to the choices he made to abandon searches for them to save his remaining daughter. The plant employees described the fatalistic belief that they would die. Firemen and soldiers trying to initiate cooling while the hydrogen explosions were happening. Powerful stuff.

tsutsuji

I watched http://www.pbs.org/wgbh/pages/frontl...lear-meltdown/ . Sensationalist spin : "the strongest earthquake that struck Japan". This is true in magnitude, but not in intensity. There are precedents of similar or stronger intensities. The picture of the tsunami hitting the cliff south of the plant is impressive. I realize that the much viewed blurry internet video of "tsunami hitting the plant" is actually tsunami hitting the cliff, not the plant. "Tokyo Tepco headquarters were in charge of tackling" : this is a quite short description for the complex emergency headquarters structures involving Tepco but also the national and local administration, the army, firemen, etc. It is the first time I hear about the people searching for tsunami survivors after the order to evacuate was issued. "They improvised". This is partly true. But reading the cabinet investigation report, I think that a number of retrofits learnt from the 2007 earthquake in Kashiwazaki Kariwa (seismic-isolated building, and fire trucks) proved helpful. For one part there is improvisation, for one part they are using safety equipments that had been thought beforehand. Sentionalist spin : "Yoshida said he was prepared to send suicide squad". "They knew that they would be exposed but they went in" while the white board actually reads 20 mSv for the fist team, 89 mSv for the second team : this is not a "suicide" level. The timeline with reactor cores starting being cooled after day 8, after the spent fuel pools are refilled by firemen does not seem accurate (the last melt down was that of unit 2 and cooling resumed on the same day on March 15: see heat plot on http://www.tepco.co.jp/en/nu/fukushi...11130_07-e.pdf page 3 (4/22) ). I think the documentary treated the "did Tepco intend to fully evacuate the plant" controversy quite well. The US specialists who says "there was clear indication of fuel damage in the fuel pools" is left uncontradicted.

curious11

Fascinating video.
Amazing amount of waste storage. Has anyone graphed the growth of this facillity? It would be interesting to extrapolate the area required over the next 10, 20 years, etc.
How radioactive is the stuff in these containers?
How resiliant are they to further earthquakes and tsunamis?

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jim hardy Recognitions: Gold Member Science Advisor	I heard on NPR a few minutes ago that tonight's PBS TV "Frontline" show will be on Fukushima reactors .

tsutsuji Recognitions: Gold Member	Also if you compare with the pictures taken in March 2011 (for example those on http://pinktentacle.com/2011/04/high...shima-daiichi/ ) it is clear that they have removed most of unit 4's roof.

curious11	Fascinating video. Amazing amount of waste storage. Has anyone graphed the growth of this facillity? It would be interesting to extrapolate the area required over the next 10, 20 years, etc. How radioactive is the stuff in these containers? How resiliant are they to further earthquakes and tsunamis?