Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[tsutsuji]

http://mainichi.jp/select/today/news/20110720k0000m010100000c.html This is a report from tonight's Tepco-government joint press conference. Tepco estimated the radiation emitted from 20 June 2011 to 28 June 2011 : 1,000,000,000 Bq/hour. This is 2,000,000 times less than the estimate for 15 March 2011. It amounts to a maximum yearly exposure of 1.7 mSv on the premises of the plant. A NISA official, Mr Hiroshi Yamagata said the goal for "step 2" (january 2012) is to achieve curbing the radiological emission inside the plant below the legal limit of 1 mSv per year.

http://www.tepco.co.jp/en/press/corp-com/release/11071905-e.html Tepco publishes the progress status of the "roadmap". Items marked with red ink on http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110719e5.pdf are announcements of new tasks added on the roadmap. For comparison, here is the progress status that was published on 17 June : http://www.tepco.co.jp/en/press/corp-com/release/11061702-e.html

http://www.nikkei.com/news/headline...1949EE3EBE290808DE3EBE2E5E0E2E3E3E2E2E2E2E2E2 Before building the cover structure at units 3 and 4, the removal of debris has priority. (Judging from what is written in http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110719e5.pdf what is meant here seems to be the debris located on the top floors of reactor buildings 3 and 4)

http://www.jiji.com/jc/zc?k=201107/2011071600400 (from the 16 July Tepco press conference) The present water treatment system has 4 km long pipes and a lot of troubles. When the end of the treatment of accumulated water in turbine buildings will become clear, they will switch to another system with short pipes. Moreover, they will increase the injection rate and bring reactor water temperature well below 100°C. Tepco is proceeding with the basic design of the ground water shielding wall.

 

[Joe Neubarth]

I have never seen I-129 mentioned in Tokyo water-related data.

The numbers for levels in drinking water published by the city only listed I-131, Cs-134 and Cs-137:
http://monitoring.tokyo-eiken.go.jp/monitoring/w-past_data.html

Same for most seawater figures released.

With its long half life it probably doesn't contribute a lot of becquerels relative to its weight, so I don't think a mixup with it would explain those becquerel figures.


Given that I-131 levels in early April where an order of a magnitude higher than cesium levels, they should have reached parity around early May. By July 4-5 when the water sludge was measured, another 8 half lives of I-131 should have passed, so I-131 should be two orders of a magnitude below cesium.


If in this particular source they were at similar levels, one would assume chemical reasons for that, i.e. cesium didn't precipitate with the mud as much iodine did. Cesium salts should be highly soluble (similar to potassium salts) and it would never occur in elementary form outside the lab. Iodine does have insoluble salts (such as silver iodide) and in elementary form is not particularly water soluble.

I thought that they were identifying the radioactive emitters by the energy level of the radiation detected therefrom.

 

[tanyaeasley]

We have discussed the video in which Arnie Gundersen spotted what looked like a single "handle" for a fuel assembly in the debris-filled unit 3 pool.

I just noticed a picture of the same pool from probably the refueling last year on this page. Look for the picture labeled "Reactor 3 refueling - mox in top left corner".

http://www.houseoffoust.com/fukushima/tepco_pics/R3_mox_upperleft.jpg

If the black items are fuel assemblies then many are quite spread out over the pool, instead of in largely complete rows as in unit 4.

According to my husband, who is in the nuclear industry and carried out a WANO inspection of a different Japanese nuke plant in December, the silvery square topped slots are the ones holding spent fuel assemblies. (Seen in upper left and upper right of photo.)

 

[NUCENG]

A question just popped into my mind.

Where could the oxygen for the hydrogen/oxygen reaction in unit two have come from?

If the overpressure/overtemperature of the containment caused a failure in the soppression chamber (torus) the oxygen was in the torus room. (This is my best guess).

If containment failure was at penetrations or PCV flange leakage the oxygen was in the air outside the containment. If the fuel pool was a source of hydrogen then the oxygen was in the air in the building. Once a breach occurred and the containment was depressurized oxygen would be able to enter the containment. But that would probably have meant a second deflagration/detonation. The relatively smaller damage to the reactor building of unit two may mean the hydrogen burn did not propogate back into containment. (Total speculation, but possible).

 

[NUCENG]

Iodine 131 Four months after Reactor Three Blew? One hundred and twenty some days after Reactor Three Building blew, and they are still finding I-131 ?

This is very frightening. As previously stated, Iodine-131 being very radioactive has a rapid half life. Every week or so half of it is gone. After 80 days it should be almost impossible to detect. Yet, here we are FOUR months after the BIG Detonation of Reactor Three and we are still seeing large amounts of Iodine 131 in water samples.

Am I wrong or should this not be happening?

Tokyo gov’t finds iodine-131 levels up to quadruple cesium levels in water reclamation centers.
July 18th, 2011 at 07:35 AM


Measurements of radioactivity in sewage treatment, etc., Sewer Authority (Tokyo), July 15, 2011:
http://translate.google.com/translate?act=url&hl=en&ie=UTF8&prev=_t&rurl=translate.google.com&sl=ja&tl=en&u=http://www.gesui.metro.tokyo.jp/oshi/infn0533.htm

It appears that you are seeing the results of a separation process that is skewing the results. The Iodine is soluble and is in the "sludge dewatering" which is the water remaining after the sludge is removed. Most of the Cs is in the sludge which has been separated. Since it isn't clear how much sludge is in how much water, I'm not sure how to interpret the relative magnitudes of the isotopes. If we had volumetric or mass concentrations of sludge and water it would make a calculation possible.

They say the dose rate readings were measured at 1 meter, but is it one meter from what?

 

[NUCENG]

According to my husband, who is in the nuclear industry and carried out a WANO inspection of a different Japanese nuke plant in December, the silvery square topped slots are the ones holding spent fuel assemblies. (Seen in upper left and upper right of photo.)

I believe you are seeing new non MOX-fuel in the upper right and new MOX fuel in the upper left. Spent fuel is darkened by thin layers of oxide and that explains the difference of the fuel distributed in the racks. Discharged fuel after five or six years isn't as bright and shiny as new.

Replacement batch sizes are generally a quarter to a third of the bundles and thae number of new MOX and non-MOX assemblies is a good chunk of the expected reload batch size.

32 MOX
64 Non MOX
96 total bundles

Unit 3 has 548 bundles in a full core.

 

[benzyme]

I read a quote from one of the farmers with contaminated hay, who said that because of the distance (150 km) and wind direction after the hydrogen explosions, he didn't think there was any risk. I was just wondering what some of you would reply to him? Would most of that contamination have been from unit 1 explosion (I think wind blew n/nw) or just steady accumulation over a few weeks/months?

 

[joewein]

I thought that they were identifying the radioactive emitters by the energy level of the radiation detected therefrom.

Yes, they are. They are not likely to confuse I-131 with I-129 from that. It almost certainly really is I-131, but for reasons discussed above the cesium got separated somewhere along the sludge and water processing path in the sewage treatment plant.

The ratio detected is unlikely to be a directly linked to nuclear decay of the respective isotopes. Somebody cherry-picked the data pointing out that in Minamitama Water Reclamation Center the I-131 was 4 times the Cs-134 level (66 vs 15 Bq/kg). At two sites I-131 was below detection level while cesium was > 100 Bq/kg. The ratios are all over the place, but "iodine at 4 times cesium levels in July" gets more attention than vice versa.

 

[joewein]

I read a quote from one of the farmers with contaminated hay, who said that because of the distance (150 km) and wind direction after the hydrogen explosions, he didn't think there was any risk. I was just wondering what some of you would reply to him? Would most of that contamination have been from unit 1 explosion (I think wind blew n/nw) or just steady accumulation over a few weeks/months?

There were two major plumes over land, from what I recall from documentaries I've seen.

The first one was traveling South over Ibaraki down to Chiba, then sweeping over the Kanto plain, touching as far south-west as Kanagawa and Shizuoka, and west into Tochigi and eastern parts of Gunma. This was the first spike registered in Tokyo. I think that was after the unit 1 venting and explosion. That's why tea in Shizuoka and Kangawa has been reaching levels beyond legal limits for food and why drinking water levels for babies and infants were briefly exceeded in Tokyo. This plume reached areas about 300 km from the plant.

The second plume headed mostly Northwest towards Fukushima City and dumping most of its contents within about 50 km, between Iitate and the plant itself, but somewhat lower concentrations reached areas to the West like Koriyama and Fukushima city further North West. The second plume coincided with the suppression chamber explosion in unit 2 and the hydrogen blast in unit 3. The most severely contaminated areas were hit by this one.

Almost certainly the bulk of the radioactive release happened during the first two weeks, especially during the containment venting operations and hydrogen explosions and before seawater injections brought temperatures down again.

The fallout pattern depends far less on proximity than on rain and snow fall on the particular day, as the precipitation extracts the radioactive load and deposits it on the ground. This was already the experience after the Chernobyl disaster: Contamination did not decrease linearly with distance, but you were truly unfortunate to see rain during those days. There is a lot of dairy farming in the picturesque alpine region of Allgäu, to the South West of Munich, Germany (1300 km from Chernobyl), but the government had to dispose of the milk there, because they ended up with a lot more I-131 than areas closer to the East that didn't have rain in late April 1986.

 

[joewein]

どうもありがとう for posting, as always!

http://mainichi.jp/select/today/news/20110720k0000m010100000c.html This is a report from tonight's Tepco-government joint press conference. Tepco estimated the radiation emitted from 20 June 2011 to 28 June 2011 : 1,000,000,000 Bq/hour. This is 2,000,000 times less than the estimate for 15 March 2011. It amounts to a maximum yearly exposure of 1.7 mSv on the premises of the plant. A NISA official, Mr Hiroshi Yamagata said the goal for "step 2" (january 2012) is to achieve curbing the radiological emission inside the plant below the legal limit of 1 mSv per year.

This way of converting the ongoing hourly release into an annual dose doesn't make any sense to me. It's like saying, if you borrow x amount of money every month, you will pay y amount of interest every year, as if it didn't matter how much you were already in debt or how many years you continued this.

Release or no release, there are already radioactive substances on the ground that produces background radiation, year after year. Maybe the rain will gradually wash out some of it and Cs-134 will decay with a half life of 2 years, but it won't go away quickly like the I-131.

A goal of 1 mSv/y (presumably on top of natural sources, not including them) seems very ambitious even outside the wrecked reactor building, let alone inside them.

EDIT: TEPCO http://www.tepco.co.jp/en/nu/fukushima-np/f1/index-e.html" at about 10 points mostly along the periphery of the plant. The official radiation readings published today (7/20) range from about 10 microsievert per hour at MP1 to 350 microsievert per hour south of the main building, near where the webcam stands. That's an annualized dose of 87 mSv to 3 Sv per year.

[URL]http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/f1_lgraph-e.gif[/URL]

Sure, you can get that down to 1 mSv per year, by not staying at the plant for more than a couple of hours a year...

EDIT 2: With this helpful http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/f1-sv-20110627-e.pdf" you can avoid hotspots of several 100 mSv/h around the reactor blocks, staying in zones with "only" 0.2-10 mSv/h.

http://www.nikkei.com/news/headline...1949EE3EBE290808DE3EBE2E5E0E2E3E3E2E2E2E2E2E2 Before building the cover structure at units 3 and 4, the removal of debris has priority. (Judging from what is written in http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110719e5.pdf what is meant here seems to be the debris located on the top floors of reactor buildings 3 and 4)

I think this will have to include partly demolishing reinforced concrete portions of both unit 3 and 4 that are in danger of collapsing, which would destroy the polyester tent. Given the significant radiation levels at least in the unit 3 pool, I think its 5F/CRF area will need remote operated machinery for cleanup. Unit 3 should be the most challenging of the units for cover construction.

 

[tsutsuji]

A goal of 1 mSv/y (presumably on top of natural sources, not including them) seems very ambitious even outside the wrecked reactor building, let alone inside them.

Sorry, I made a mistake. The measured 1.7 mSv and the 1 mSv goal mentioned in the Mainichi article apply to the site boundary, not to inside the site.

Excluding the effect of already released radioactive materials, evaluation of exposure doses at the site boundary using the current release rate (approximately one billion Bq/hour) showed that the maximum exposure dose is 1.7 mSv/year.
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110719e6.pdf

http://mainichi.jp/select/opinion/closeup/news/20110720ddm003040043000c.html The present US-French-Japan water treatment system is a desperate effort with a durability of one year. Although repairing the containment vessel is indispensable, Tepco removed it from the schedule, because preventing accumulated water from overflowing has priority. The water treatment system is the plant's "safety net". Tepco added the study of the full-fledged water treatment system in "step 2" of the roadmap. At present this full fledged system is a clean slate. The person in charge at Tepco said it must be based on simple design with short pipes. Large sections of the 4 km pipes at the present water treatment system don't pass the country's earthquake safety standards. Pr. Koji Okamoto of Tokyo university said it is possible to achieve cold shut-down ahead of schedule, if the closed loop cooling system proceeds smoothly. The next system should be based on learning the lessons from the present system and combining Japanese technology with few troubles.

http://mainichi.jp/select/jiken/news/20110720ddm010040105000c.html The removal of fuel from pools will not start sooner than 3 years from now. The removal of fuel from reactors, not before 10 years from now. At Three Mile Island it took 10 years to remove the fuel from only one reactor. In comparison, Fukushima Daiichi has 3 accidented reactors, collapsed reactor buildings, serious reactor damage and radiological pollution. There are 1496 fuel assemblies in reactors and 3108 in pools, among which 2724 are spent fuel. Because there are few damages to the fuel assemblies in the pools, moving them to the common fuel pool is being considered. In normal time fuel is reprocessed at Rokkasho, Aomori prefecture, but the damaged fuel cannot be removed with usual equipment. Remote-controlled equipments to cut and transport melted fuel are necessary. Minister Goshi Hosono said the final disposal site must be located outside Fukushima prefecture. The Nuclear Safety Commission is forming an expert committee to study those questions. As it is difficult to do this with Japanese technology alone, cooperation from abroad is indispensable.

http://sankei.jp.msn.com/affairs/news/110720/dst11072013030016-n1.htm At 5 AM, 20 July, unit 1 RPV bottom temperature passed below 100°C, with 98.9 °C. However the accuracy of the temperature measurement is questioned.

http://headlines.yahoo.co.jp/videonews/jnn?a=20110719-00000058-jnn-soci A new video acquired by JNN, showing the tanks storing the low-contaminated water from units 5 and 6, and a site being prepared to store the highly radioactive debris. The storing must go on as long as ground water seeps into units 5 and 6.

 

[joewein]

Sorry, I made a mistake. The measured 1.7 mSv and the 1 mSv goal mentioned in the Mainichi article apply to the site boundary, not to inside the site.

Thanks for the correction, tsutsuji.

Again, checking the TEPCO map of the monitoring posts against Google Maps, it seems MP1-MP8 are all at most 150 m from the site boundary. For scale on http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/f1_lmap-e.gif", it's about 1200 m from the north side of the breakwaters to the south side, or about 3600 m from the northern tip of the plant site to the southern tip.

About 100 / 120 microsieverts / hour at MP-7 / MP-8 some 150 m inside the fence is 1700 / 2000 times the level we have in Tokyo right now (0.058 microsieverts / hour). That's 870-1000 mSv per year. I find it hard to believe it should be 1.7 mSv just the other side of the fence. The wind that contaminated MP-7 and MP-8 would not have cared too much about that fence...

 

[tsutsuji]

Sorry I should have said "estimated" not "measured". Please note that they say "Excluding the effect of already released radioactive materials". I think it means that things are not going to worsen by more than 1.7 mSv over a year. But the present radiation level at the MP-x measurement points is already very high and bad, as you said.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110720/index.html The utilization rate of the water treatment facility for the past week is 50%. The 70% target is not achieved. As a consequence of the typhoon, the water level in the basement of unit 1 reactor building rose by 13 cm between July 19th and July 20th.

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110720e14.pdf the water treatment facility treated 4,510 m³ from July 13 to July 19, against 6,130 m³ during the preceding week ( http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110713e10.pdf ) (and a design capacity of 50 m³/hour *24*7 = 8,400 m³/week). Utilization rate : 4,510/8,400 = 53.7% (against 6,130/8,400 = 73.0%).

 

[Atomfritz]

[URL]http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/f1_lgraph-e.gif

[/URL]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110720/index.html[...]. As a consequence of the typhoon, the water level in the basement of unit 1 reactor building rose by 13 cm between July 19th and July 20th.

This is highly interesting.
The typhoon did really great decontamination work, reducing the background radiation by some percent.

According to the diagram above from joewein's post I think there have been at least four big swells each pushing down the background radiation a bit further.
Some curies will probably have ended up in the ocean.

 

[LabratSR]

A great piece about the work done at Oak Ridge National Labs on severe accident mitigation and station blackout.

http://sustainableenergytoday.blogspot.com/2011/07/post-47-tv-asahi-interview-on-bwr.html

 

[tsutsuji]

http://www3.nhk.or.jp/news/html/20110721/t10014352981000.html The rainfall from the beginning of the rain on 19 July to 21 july 11 AM measured in Namie town was 115 mm. The water level in unit 1 reactor building basement rose by 44 cm from 20 July to 21 July. The water treatment facility was mistakenly shut down at 08:40 this morning. There was a plan to shut down the facility as part of an electric power supply maintenance/construction work, but it was planned in the afternoon. The mistake was made during the preparation of that work.

http://www.asahi.com/national/jiji/JJT201107210053.html The 08:38 AM automatic shut down is the consequence of not having studied the consequences of the electric power line work. The original plan was a manual shut down at 03:00 PM. Tepco was aware that the power supply of the water level gauge at the tank between the decontamination facility and the desalination facility was turned off. What it was not aware of, was that this would trigger the automatic shut down of the whole facility. This mistaken shutdown will result into a 3 percentage points drop of the weekly utilization rate.

http://www.tepco.co.jp/nu/fukushima-np/images/handouts_110721_01-j.pdf mentions the 08:38 AM shut down being a consequence of the doubling of the Yonomori power line.

http://www.nikkei.com/news/category...E3E2E2E18DE0E3E2E5E0E2E3E39F9FE2E2E2E2;at=ALL A sense of uncertainty is emerging out of the water treatment facility's poor utilization rate while Tepco's goal to treat 200,000 tons by the end of this year remains unchanged.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110721/0415_198.html The number of whereabouts unknown Fukushima Daiichi workers whose health cannot be checked rose to 198.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110721/index.html the special committee in charge of middle and long term questions is formed by Japan Atomic Energy Commission (not Japan Nuclear Safety Commision as I wrote above: sorry for the mistake). The 20 member committee comprises the 5 members of Japan Atomic Energy Commission and nuclear energy experts or Tepco advisers. They will use Three Mile Island as a reference. They are expected to reach their conclusions by the end of "step 2" in January 2012.

based on [a] false report, the central government established the Japan Atomic Energy Commission in 1956.
http://www.asahi.com/english/TKY201107180285.html

http://www.aec.go.jp/jicst/NC/about/kettei/kettei110721.pdf Japan Atomic Energy Commission Decision of 21 July 2011 : lists the 20 member names and 3 study objectives : (1) modalities of middle to long term efforts (2) effective technology development problems (3) international cooperation

 

[joewein]

http://www.nikkei.com/news/category...E3E2E2E18DE0E3E2E5E0E2E3E39F9FE2E2E2E2;at=ALL A sense of uncertainty is emerging out of the water treatment facility's poor utilization rate while Tepco's goal to treat 200,000 tons by the end of this year remains unchanged.

At least they're no longer putting all their eggs in one basket, as the http://www.tepco.co.jp/en/nu/fukushi...10714_06-e.pdf" is supposed to start operating from August. It has two processing trains that will provide an alternative to the Areva / Kurion system, with a similar target capacity. Let's hope it works better.

Maybe the bet is that either Areva / Kurion or Toshiba-IHI-Shaw would eventually work as designed, or that if both only manage to achieve half of what they were sold as, the combined throughput will still save the original goal.

It's been a while since I last heard anything about how many days were left before TEPCO would run out of storage for contaminated water...


Meanwhile the story about fall-out in rice straw used as cattle feed for beef cattle is getting worse:

The Miyagi prefectural government said Tuesday that three companies in the northeastern Japan prefecture have shipped a total of about 77 tons of rice straw containing radioactive cesium above the legal limit to five prefectures.
(...)
According to tests conducted by all five prefectures except Aomori, the straw showed radioactive cesium readings of between 8.0 to 25.8 times the legal limit of 300 becquerels per kilogram after adjustment for damp.

(http://jen.jiji.com/jc/eng?g=eco&k=2011071900919")

A man in Osaki, Miyagi Prefecture, who sold straw contaminated with high levels of radioactive cesium told the Mainichi on July 18 that he had never imagined that his straw was contaminated because the city is about 150 kilometers away from the crippled Fukushima No. 1 Nuclear Power Plant.

(http://mdn.mainichi.jp/mdnnews/news/20110719p2a00m0na011000c.html" )

It looks like the radioactive plume got as far as the northern part of Miyiagi prefecture. It makes you wonder what else besides straw bales was contaminated on those farms and how much cesium will be found in the soil across Miyagi prefecture (which lies to the North of Fukushima).

Smaller shops here have raised their prices for rice from about 1500 yen to 2000 yen per 5 kg bag because they've been experiencing difficulties getting supplies. More and more consumers are stocking up on 2010 rice, as it's yet to be seen what cesium levels will be found in 2011 rice 8 weeks from now, when it will be harvest time. We've heard very little about soil or other testing in rice growing areas so far, which is not reassuring.

 

[tsutsuji]

http://www.asahi.com/national/update/0722/TKY201107220127.html A partial blackout started at 07:10 this morning after a breaker tripped in a switchboard. The water treatment facility, some of the reactor surveillance equipments, spent fuel pool cooling systems and other systems stopped suddenly. The water injection into reactor cores, based on another power source, is going on. The circuit breaker might have broken down.

http://www.sanin-chuo.co.jp/newspack/modules/news/article.php?storyid=1114536015 This morning's blackout concerned the power supply to units 3 and 4, which is also supplying the water treatment system. Unit 3 spent fuel pool, the common fuel pool, and reactor surveillance equipments stopped. The power supply was recovered at 04:00 PM this afternoon. No sudden rise of temperature was observed at any pool.

http://www.yomiuri.co.jp/science/news/20110722-OYT1T00795.htm Equipments were sequentially switched to backup power source(s), resulting into full recovery at around 03:30 PM. The blackout did not affect the plant safety.

http://sankei.jp.msn.com/region/news/110722/fks11072211580002-n1.htm As part of the work to double the power line to units 5 and 6, units 3 and 4 had been switched to the power supply for units 1 and 2. The breaker that tripped is located on the power line supplying units 3 and 4 from units 1 and 2. The blackout cause is either the power consumption from units 3 and 4 was too much, or the breaker failed. The expected temperature rise in SFP 3 was 0.3 °C/hour.

The flow of information from Fukushima Daiichi is likely to decline from next week :

press conferences by the joint government-TEPCO disaster task force, which from April 25 had in general been held every day, will from next week only be held once on Mondays and once on Thursdays.
http://mdn.mainichi.jp/mdnnews/news/20110721p2a00m0na007000c.html

 

[gmax137]

I would like to know if the plant service water pumps survived the earthquake & tsunami. Sorry, I don't know how they are called in these plants - I'm talking about the pumps that provide seawater to cool the essential heat loads (diesels, RHR, etc.). So much emphasis now on SBO, but if the service water pumps didn't survive then loss of AC power was only part of the problem.

 

[MJRacer]

I would like to know if the plant service water pumps survived the earthquake & tsunami. Sorry, I don't know how they are called in these plants - I'm talking about the pumps that provide seawater to cool the essential heat loads (diesels, RHR, etc.). So much emphasis now on SBO, but if the service water pumps didn't survive then loss of AC power was only part of the problem.

See http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110525_01-e.pdf

Page 37, second picture from left at bottom of the page.

 

[joewein]

See http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110525_01-e.pdf

Page 37, second picture from left at bottom of the page.

In http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110525_01-e.pdf" on page 50 I found a mention of air-cooled diesels at units 2 and 4. Previously I had only ever heard about one air-cooled diesel surviving in unit 6, saving both units 5 and 6 by powering their RHR system.

Until now I had wondered if units 1-4 could have survived if they had also had some air-cooled diesels, but the answer seems to be "no": They had them and they didn't make it.

If the emergency diesels in units 1-4 failed because of loss of sea water for cooling, one would expect the air-cooled units to have been unaffected. So the diesel in unit 2 could have operated the RHR for units 1 and 2 and the one in unit 4 could have run the RHR for 3 and 4.

Elsewhere I've seen it mentioned that their fuel tanks were swept away. Then of course when the basements were flooded, where all diesels were located, that would take out even the air-cooled ones.

Last but not least we have the electric switchboards there flooded by sea water.

From all of this it sounds like the were five hits by either the quake or the tsunami, the combination of which doomed the reactors:

1. quake: simultaneous destruction of all grid connections
2. tsunami: flooding of electric sea water pumps for diesels and RHR => loss of ultimate heat sink for water-cooled diesels, cores and spent fuel pools
3. tsunami: loss of fuel supply to emergency diesels
4. tsunami: loss of all diesels themselves due to turbine hall basement sea water flooding
5. tsunami: loss of electrical system due to turbine hall basement sea water flooding

The water-cooled diesels couldn't run without sea water, but even the air-cooled diesels needed fuel and somewhere to feed the power that wasn't shorted by salt water flooding.

Even after the first three problems the station could conceivably still have survived if emergency generators had been brought in quickly enough, but the flooding of the electrical systems meant that when they did eventually manage to find cables long enough to connect tuck-mounted mobile generators they shorted.

Perhaps those flooded switchboards were the worst single point of failure.

The loss of sea water for RHR and even for the diesels on its own would not have been fatal, as demonstrated by units 5 and 6. As we read on page 50 of that http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110525_01-e.pdf", units 5 and 6 also lost their RHR sea water supply, yet they were saved by the combination of one air-cooled diesel that still had fuel and by temporary pumps and hoses set up by the fire brigades and emergency workers.

Those temporary pumps and hoses were recently in the news, when a pump failed and it took several hours to replace it.

It sounds like both units 5 and 6 and Fukushima Daini were located high enough that the turbine halls and reactor buildings doors weren't reached by the flood and in Daini the sea water pumps were better protected by being enclosed in a small concrete building.

 

[MJRacer]

In http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110525_01-e.pdf" on page 50 I found a mention of air-cooled diesels at units 2 and 4. Previously I had only ever heard about one air-cooled diesel surviving in unit 6, saving both units 5 and 6 by powering their RHR system.

Until now I had wondered if units 1-4 could have survived if they had also had some air-cooled diesels, but the answer seems to be "no": They had them and they didn't make it.

If the emergency diesels in units 1-4 failed because of loss of sea water for cooling, one would expect the air-cooled units to have been unaffected. So the diesel in unit 2 could have operated the RHR for units 1 and 2 and the one in unit 4 could have run the RHR for 3 and 4.

Elsewhere I've seen it mentioned that their fuel tanks were swept away. Then of course when the basements were flooded, where all diesels were located, that would take out even the air-cooled ones.

Last but not least we have the electric switchboards there flooded by sea water.

From all of this it sounds like the were five hits by either the quake or the tsunami, the combination of which doomed the reactors:

1. quake: simultaneous destruction of all grid connections
2. tsunami: flooding of electric sea water pumps for diesels and RHR => loss of ultimate heat sink for water-cooled diesels, cores and spent fuel pools
3. tsunami: loss of fuel supply to emergency diesels
4. tsunami: loss of all diesels themselves due to turbine hall basement sea water flooding
5. tsunami: loss of electrical system due to turbine hall basement sea water flooding

The water-cooled diesels couldn't run without sea water, but even the air-cooled diesels needed fuel and somewhere to feed the power that wasn't shorted by salt water flooding.

Even after the first three problems the station could conceivably still have survived if emergency generators had been brought in quickly enough, but the flooding of the electrical systems meant that when they did eventually manage to find cables long enough to connect tuck-mounted mobile generators they shorted.

Perhaps those flooded switchboards were the worst single point of failure.

The loss of sea water for RHR and even for the diesels on its own would not have been fatal, as demonstrated by units 5 and 6. As we read on page 50 of that http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110525_01-e.pdf", units 5 and 6 also lost their RHR sea water supply, yet they were saved by the combination of one air-cooled diesel that still had fuel and by temporary pumps and hoses set up by the fire brigades and emergency workers.

Those temporary pumps and hoses were recently in the news, when a pump failed and it took several hours to replace it.

It sounds like both units 5 and 6 and Fukushima Daini were located high enough that the turbine halls and reactor buildings doors weren't reached by the flood and in Daini the sea water pumps were better protected by being enclosed in a small concrete building.

I think http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110516e22.pdf" is a better illustration than page 66 of the May 24, 2011 TEPCO presentation of the damages on the station power facilities in Fukushima Daiichi Nuclear Power Station.

Also: http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110516e18.pdf".

Page 46 of the TEPCO presentation shows that Fukushima Dai-ni (F#2) was built at O.P.+12m (O.P. IIRC is Onohama Peil or about mean sea level), whereas Fukushima Dai-ichi (F#1) was built at O.P.+10m for Units 1 to 4 and at O.P.+13m for Units 5 & 6 (which helped save the one diesel as the flood was only about 30cm there).

Just 2-3 meters made a lot of difference. However, the seaside pumps at Dai-ni also had a building around them that protected them better from the tsunami (2nd Picture from left at bottom of page 46).

And, yes the switchboards flooded with sea-water made the temporary station blackout (SBO), for all practical purposes, as good as permanent (the high voltage switchboard (M/C) operated at 6,900v and the "low" voltage switchboard (P/C) operated at 480v).

More detail can be seen in the following diagrams. First is a http://2.bp.blogspot.com/-UtgJZNeAdlU/Ta3z9i97ryI/AAAAAAAAEfs/HehSEK2k60I/s1600/R1-R4.PNG" with schematic drawings of the estimated sea water piping circuits.

At the top, the sea-side pumps are identified as "Pompe intake acqua mare" in blue. At the bottom right is a legend identifying the pipes carrying cooling seawater as "condotte intake acqua di mare" in dark green. Above it is a legend showing the switchboards for unit 3 in lighter green. The legend (in blue) says "sala quadri electtrici R3 interrata a OP+300," which I translate as electrical switchboard hall for Unit 3 buried at OP+300 (in this case millimeters). Ground level at this point was OP+10,000mm. At the bottom left there is a legend beginning with "Sovrapposizione ..." which I translate as superposition of the buried plan view of Reactor 3 in relation to the turbine building at various heights (OP-2060mm (the torus was below sea-level?), OP+1900mm (the diesel generators) and OP+300mm (the switchboards)). So the switchboards were apparently 1.6 meters or more than 5 ft below the generators.

Unit 3 can be seen in more detail http://3.bp.blogspot.com/-JaxFid8Qo...Ako/t5TVRl5sb-4/s1600/R3++completa+small.jpg".

The generators are at the top above the turbines (look for the word "diesel") and the switchboards are at the bottom in light green bracketed in blue with a note that says that Unit 2 probably did not have them or did not have them at that location. It is unclear if these switchboards were common to both units.

In hindsight, the seaside pumps may have been hardened at Dai-ichi like they were at Dai-ni by protecting them with a building, but there was no cure for the switchboards other than relocating them completely once the reactors were built. Obviously, the diesel generators could have been relocated as well.

 

[tsutsuji]

Fukushima Daiichi nuclear power plant:

http://www.jiji.com/jc/c?g=soc_30&k=2011072300145 Yesterday's blackout is the result of a simple breaker adjustment mistake. The breaking limit had been set too low when it was installed in May. Tepco will futher investigate whether the instruction manual was not clear enough. Tepco is changing the hoses at the exit of the Areva system as part of an experiment to check whether the cause of the declining flow rate is sludge sticking to the hose's inner surface, thus reducing the inner diameter.

http://www3.nhk.or.jp/news/html/20110723/t10014404491000.html The breaking current had been mistakenly set at one third of the normal value.

Hamaoka nuclear power plant unit 5 (this is a shut down unit with already a number of serious problems : see https://www.physicsforums.com/showthread.php?p=3313860&highlight=hamaoka#post3313860 and following posts) :

http://mainichi.jp/area/shizuoka/news/20110713ddlk22040177000c.html (Shizuoka local page of Mainichi dated 13 July 2011) 40 m³ of water devoid of radioactive substances leaked. On 12 July at 10:20 AM a flood alarm was issued in the basement of the reactor building. Traces of a water leak were observed by an employee on the second floor. The water may have run through the interval between the floor and the wall and reached the basement. Some equipments were flooded and broke down. The washing of equipments to remove salt accumulated as a result of last May's condenser sea water leak, was being performed. The diameter 25 cm PVC hose bringing water from the desalinated water tank seems to have failed. Chubu Electric is investigating the cause.

http://mainichi.jp/area/shizuoka/news/20110721ddlk22040036000c.html (Shizuoka local page of Mainichi dated 21 July 2011) On 20 July Chubu Electric said the worker bent the hose with an 85 cm radius while the hose specification requires a minimum radius of 3 metres. The leaked water flowed from the upper second floor to the underground second floor. It accumulated for a while in a liquid waste system tank, but the quantity being too much, it flowed backwards in the piping. 1.9 m³ of water containing radioactive substances overflowed from basement first and second floor's drainage ditches. It is believed that radioactive substances were adhering to the piping. The total amount of radiation is 2,280,000 Bq. None of it has leaked to the outside. Chubu Electric is working at wiping this contaminated water out. Chubu Electric said it was already aware of the radioactive water leak on 12 July. It explained that because the national reporting standard of 3,700,000 Bq had not been reached, it was publicly disclosed together with the disclosure of the damage cause.

http://www.chuden.co.jp/energy/hamaoka/hama_info/hinf_unten/__icsFiles/afieldfile/2011/07/15/230715saikangentai.pdf 15 July press release on the condenser trouble.
http://www.chuden.co.jp/energy/hamaoka/hama_info/hinf_tenken/__icsFiles/afieldfile/2011/06/17/230617shuhukusuiki.pdf 17 June press release on the condenser trouble.
http://www.chuden.co.jp/energy/hama...fieldfile/2011/07/04/230520shuhukusuiki5u.pdf 20 May press release on the condenser trouble.

Hamaoka nuclear power plant (all units):

http://www.asahi.com/national/update/0721/NGY201107200047.html Chubu Electric is going to raise the height of the 1.5 km long sand dune as a measure enhancing tsunami safety. The sand dune being a natural formation, its height is uneven. The lowest parts will be raised by 2 m. Chubu is also planning to build a seawall between the dune and the plant.

Chubu Electric Power Co. said Friday it will build seawalls as high as 18 meters at its Hamaoka nuclear plant
http://search.japantimes.co.jp/cgi-bin/nn20110723a1.html

http://www.chuden.co.jp/english/corporate/ecor_releases/erel_pressreleases/__icsFiles/afieldfile/2011/07/22/0722E_1.pdf 33 page long English language press release "Countermeasures for Tsunami in Hamaoka NPS"

Genkai nuclear power plant (Kyushu, Western Japan):

The discovery of errors in data incorporated in a report on the No. 3 reactor at the Genkai Nuclear Power Plant in Saga Prefecture illustrates problems with its operator's checking system and the government regulator's ability to examine safety data. (...) Two years passed before the errors were found.
http://mdn.mainichi.jp/mdnnews/news/20110723p2a00m0na015000c.html

 

[gmax137]

...

...

Thanks you guys! One thing to note, I think the seawater lines noted above are the main circulating water to & from the condensers; this is different from the safety-related sea water cooling of the RHR and other vital heat loads.

I'm still not sure whether the safety-related cooling survived the tsunami (but the photos of the intake area don't look good). My only point here is that typically the plant would shutdown but stay hot, with decay heat removal via RCIC (this is achieved by steam-driven pump providing water to be boiled off in the reactor). After some time they would then cooldown and get on RHR. If the safety-related cooling pumps were destroyed by the tsunami, then the RHR isn't going to work, and once the water supply to RCIC is used up, then heat removal won't be possible. Alternate water sources are typically not seismic, so there may have been loss of heat removal capability even if the diesels & switchgear were operable.

 

[tsutsuji]

If the safety-related cooling pumps were destroyed by the tsunami, then the RHR isn't going to work, and once the water supply to RCIC is used up, then heat removal won't be possible.

So if the water supplying tank is big enough, you can rely on the RCIC over an extended time :

According to the link provided by LabratSR at https://www.physicsforums.com/showpost.php?p=3413453&postcount=10680

Assured cooling water supply: a secure, large condensate storage tank capable of supplying water to the HPCI/RCIC system for extended periods (this was not an issue in our SBO analyses). Alternatively, dedicated diesel-powered portable pumps can be staged to provide this function from other water sources.
http://sustainableenergytoday.blogspot.com/2011/07/post-47-tv-asahi-interview-on-bwr.html

At Fukushima unit 5 and unit 6

On March 19, a temporary seawater pump was installed to activate the RHR system

pages IV-99 and IV-102 http://www.iaea.org/newscenter/focus/fukushima/japan-report/chapter-4.pdf

See also the diagram "installation of backup RHRS pump" page 78 of http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110525_01-e.pdf.

At Fukushima units 1-2-3-4 after they ran out of fresh water, they pumped water directly from the sea

for example for unit 2

At 19:54 on March 14, the seawater injection into the reactor using fire engines was started.

page IV-58 http://www.iaea.org/newscenter/focus/fukushima/japan-report/chapter-4.pdf

It seems that finding a pump and (sea)water would not really be a problem if everything else would work fine.

At unit 2 the problem was not running out of water. The problem was the RCIC stopping for some not well identified reason :

From that point until 13:25 on March 14, the reactor water level began to drop, at which point the RCIC was judged to have shut down.

page IV-58 http://www.iaea.org/newscenter/focus/fukushima/japan-report/chapter-4.pdf

the fuel was uncovered for five hours from 13:25 on March 14 (75 hours after the Earthquake began) and [...] the core damage started two hours later.

p IV-59 and IV-60 http://www.iaea.org/newscenter/focus/fukushima/japan-report/chapter-4.pdf

 

[joewein]

At unit 2 the problem was not running out of water. The problem was the RCIC stopping for some not well identified reason :

The RCIC still needs battery power for operating valves and this could have run out. Another possibility is that, since the RCIC uses the suppression chamber pool as its heat sink, which is also heated by venting from the RPV, the suppression chamber pool became too hot to condense steam, which would stop the RCIC turbine.

Also, we should remember that not all units had an RCIC: Unit 1 only had an isolation condenser and perhaps not by coincidence, is assumed to have suffered meltdown only about 5 hours after station blackout, 2-3 days before the other units.

Great suggestions in http://sustainableenergytoday.blogspot.com/2011/07/post-47-tv-asahi-interview-on-bwr.html" :

Assured containment cooling: A secure means of cooling the primary containment pressure suppression pool and drywell atmosphere under SBO conditions. A number of options are possible, but the use of diesel-driven RHR pumps and drywell coolers powered by backup power systems are options.

Had there been a way of using temporary sea-water pumps to cool the suppression chamber or containment, the RCIC could have operated longer and containment venting would have been much less urgent, as steam could have continually been condensed inside.

Also, if the designers of the RCIC had run a generator off its steam turbine and not just a water pump, the dependence on batteries for operating RCIC valves would not have been its Achilles heel.

 

[tsutsuji]

Concerning Fukushima Daiichi unit 3, Tepco says on the one hand "The inability to use the residual heat removal system seawater pumps meant the loss of residual heat removal system (RHR) functions, resulting in a failure to shift the decay heat in the PCV to the sea, the final heat sink", then a few lines below : "The reason why the RCIC stopped at 11:36 on March 12 is unknown at this time, but the storage batteries for valve manipulation might have become exhausted as more than 20 hours had passed since the RCIC started operation" (page IV-73 http://www.iaea.org/newscenter/focus/fukushima/japan-report/chapter-4.pdf ) so that it seems that the loss of the seawater pumps was not the immediate cause of the accident.

Great suggestions in http://sustainableenergytoday.blogspot.com/2011/07/post-47-tv-asahi-interview-on-bwr.html" ad there been a way of using temporary sea-water pumps to cool the suppression chamber or containment, the RCIC could have operated longer and containment venting would have been much less urgent, as steam could have continually been condensed inside.

My understanding is that the RCIC turbine basically needs a difference of pressure. Did we reach a point when the pressure in the suppression chamber became so high that the steam flow in the RCIC turbine was not enough to move the turbine ?

If the safety-related cooling pumps were destroyed by the tsunami, then the RHR isn't going to work, and once the water supply to RCIC is used up, then heat removal won't be possible.

Basically this is the problem they had at Fukushima Daini unit 1 as indicated on the right part of the table page 62 of http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110525_01-e.pdf : they had lost their RHR sea water pump, but nearly everything else was all right. And they managed to keep the reactor stable enough until they could repair that pump by changing the motor (see page 54 http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110525_01-e.pdf and "The motors of the RHR system cooling water pump (D) and emergency component cooling water pump (B) necessary for the RHR system (B) operation were replaced with new ones in order to maintain a means of heat removal by the RHR. (...) As a result, the operation of the RHR system (B) started to cool the suppression chamber at 01:24 on March 14" : page IV-115 http://www.iaea.org/newscenter/focus/fukushima/japan-report/chapter-4.pdf ) .

 

[joewein]

My understanding is that the RCIC turbine basically needs a difference of pressure. Did we reach a point when the pressure in the suppression chamber became so high that the steam flow in the RCIC turbine was not enough to move the turbine ?

According to the http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/cur/data/pres-un2-t.txt" , the unit 2 S/C was under about 6 bar of pressure on March 13 (I assume the unit is KPa):

2011-03-13 | 10:35:00 |  10
2011-03-13 | 13:00:00 | 590
2011-03-13 | 14:10:00 | 600

Same data for http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/cur/data/pres-un3-t.txt" :

2011-03-13 | 07:05:00 |  430
2011-03-13 | 07:10:00 |  430
2011-03-13 | 07:15:00 |  435
(...)
2011-03-13 | 08:35:00 |  445
2011-03-13 | 08:55:00 |  455
2011-03-13 | 09:10:00 |  590
2011-03-13 | 09:15:00 |  590

Unfortunately there appears to be no published temperature data for the torus in the first couple of days, but if the published pressure was due to steam, the suppression pool water must have been pretty hot by then. http://www.efunda.com/materials/water/steamtable_sat.cfm" at 146 deg C at 430 KPa and at 159 deg C at 600 KPa. It would not have been very good at condensing steam from the RCIC at that temperature, or put another way, the RCIC turbine would have had a lot of back pressure even if input pressure was over 6 MPa.

At Fukushima-II, which has BWR5 reactors (same as unit 6 at F-I) the suppression pools of units 1, 2 and 4 topped 100 deg C on the morning after the quake (reported to NISA: unit 1 @ 05:22 on 2011-03-12; unit 2 @ 05:32; unit 4 @ 06:07) after the RHR lost its sea water supply. Unit 3 was OK because its sea water pumps were undamaged. They only recovered after the sea water pumps were repaired and the RHR restarted. Admittedly, the F-II data doesn't necessarily tell us much about timing, as they used a different containment (mark 2 vs. mark 1) as well as having a higher power rating (1100 MWe vs. 784 MWe).

 

[tsutsuji]

It would not have been very good at condensing steam from the RCIC at that temperature, or put another way, the RCIC turbine would have had a lot of back pressure even if input pressure was over 6 MPa.

If the suppression pool pressure rises to such heights that the steam flow won't move the RCIC turbine, couldn't you, as a last resort measure, vent the suppression pool into the atmosphere ? Steam engines don't need a cooling system provided you are allowed to release the steam into the atmosphere.

It sounds like both units 5 and 6 and Fukushima Daini were located high enough that the turbine halls and reactor buildings doors weren't reached by the flood and in Daini the sea water pumps were better protected by being enclosed in a small concrete building.

Actually units 5 and 6 did suffer flooding as shown by http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110516e22.pdf (unit 5 exciters submerged, or unit 6 switchboards submerged) (thanks MJracer for the link). However unit 6's diesel generator 6B, being located on the ground floor in a separate building, and being air-cooled, survived. That building was surrounded by a 0~1 m high wave above ground, as shown on http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110525_01-e.pdf page 36. Either the wave was lower than the sensitive parts of the 6B diesel generator, or the door and walls were tight enough and no water entered the building.

More detail can be seen in the following diagrams. First is a http://2.bp.blogspot.com/-UtgJZNeAdlU/Ta3z9i97ryI/AAAAAAAAEfs/HehSEK2k60I/s1600/R1-R4.PNG" with schematic drawings of the estimated sea water piping circuits.

(...)
At the bottom left there is a legend beginning with "Sovrapposizione ..." which I translate as superposition of the buried plan view of Reactor 3 in relation to the turbine building at various heights (OP-2060mm (the torus was below sea-level?), OP+1900mm (the diesel generators) and OP+300mm (the switchboards)). So the switchboards were apparently 1.6 meters or more than 5 ft below the generators.

Unit 3 can be seen in more detail http://3.bp.blogspot.com/-JaxFid8Qo...Ako/t5TVRl5sb-4/s1600/R3++completa+small.jpg".

The generators are at the top above the turbines (look for the word "diesel") and the switchboards are at the bottom in light green bracketed in blue with a note that says that Unit 2 probably did not have them or did not have them at that location. It is unclear if these switchboards were common to both units.

"the torus was below sea-level?" : Yes, this is confirmed on the figure page 5 of http://www.kantei.go.jp/foreign/kan/topics/201106/pdf/attach_04_3.pdf. It is aslo known that unit 1's reactor building reaches at least 1.23 m below sea level as "The measuring point in the basement of R/B of Unit 1 [is] O.P.-1,230mm" : http://www.nisa.meti.go.jp/english/press/2011/06/en20110616-1-5.pdf

"OP+300mm (the switchboards)" and "apparently 1.6 meters" : Actually the height indicated for that level on http://3.bp.blogspot.com/-JaxFid8Qo...AAko/t5TVRl5sb-4/s1600/R3++completa+small.jpg is OP -300 mm (minus 300 milimeters). So the switchboards were apparently 1.9+0.3=2.2 meters lower than the Diesel Generators. The OP+1900 mm height of diesel generators is approximately confirmed by the figure page 5 of http://www.kantei.go.jp/foreign/kan/topics/201106/pdf/attach_04_3.pdf although no dimension is explicitly written.

In hindsight, the seaside pumps may have been hardened at Dai-ichi like they were at Dai-ni by protecting them with a building, but there was no cure for the switchboards other than relocating them completely once the reactors were built. Obviously, the diesel generators could have been relocated as well.

The seawater pump buildings at Daini were not so helpful. It turns out that 3 out of 4 seawater pumps broke down. I would be happy to know the exact reason why the remaining one (the one belonging to unit 3) survived, though.

I think the background of http://www.tepco.co.jp/en/news/110311/images/110717_1.jpg (or http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110717_01-e.pdf ) is, from left to right : the Futaba and Yonomori power lines, unit 5 reactor building and unit 5 turbine building.[/URL]

This can also be confirmed by the matching of color patterns on unit 5 reactor building as pictured on http://www.houseoffoust.com/fukushima/tepco_pics/fukudaiichi5_6.jpg available from http://www.houseoffoust.com/fukushima/phototour.html (see also http://www.houseoffoust.com/fukushima/tepco_pics/fuku_switchingstation2.jpg showing the other side of the 500 kV unit 5 and 6 switching station)

Thanks for all these informative links. I was not aware there was a fallen crane?

We talked about it in May : http://www.netimago.com/image_202944.html

At long last, I found a picture showing the crane (near unit 6 water intake) before the tsunami : http://www.houseoffoust.com/fukushima/tepco_pics/r6_waterpump4.jpg (incidentally, this is also a good comparison reference for the breakwater damages)

 

[tsutsuji]

http://www.fnn-news.com/news/headlines/articles/CONN00203983.html the installation of a bypass hose at the exit of the Areva system requires working in a 50 mSv/hour environment. At 11:00 AM on 24 July, the injection flow into unit 1 reactor was found to be down from 3.5 to 3.3 m³/hour. Tepco raised it to 3.8 m³/hour.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110724_01-e.pdf (page 2) T-hawk helicopter doing its job taking dust samples on reactor buildings on 22, 23, 24 July.

 

[NUCENG]

If the suppression pool pressure rises to such heights that the steam flow won't move the RCIC turbine, couldn't you, as a last resort measure, vent the suppression pool into the atmosphere ? Steam engines don't need a cooling system provided you are allowed to release the steam into the atmosphere.

RCIC and HPCI are designed to operate over a significant pressure range. However at some point the design basis for ECCS system transfers to low pressure injection systems (RHR and Core Spray. Also,fire trucks and other portable pumps would have a hard time pumping into a 6 MPa RPV). HPCI and RCIC turbines use a reversing water wheel design to extract maximum energy from the steam they use. Back pressure is considered in the design, but would not have been a problem for the turbines at the pressures indicated in the torus at Unit 2 or 3. The bigger problem is that once the suppression pool temperature exceeds the saturation point the result of continuing HPCI or RCIC operation is to add uncondensed high pressure steam into the suppression chamber threatening the containment integrity. At this point operators would also lose the ability to control RPV pressures with SRVs without damaging the containment. The lack of Suppression Pool and Drywell temperature data makes it difficult to determine if this happened at either Units 2 or 3.

HPCI and RCIC systems also have a low pressure steam supply isolation trip about 500 to 600 kPa (at least in US plants) to recognize that the Low Pressure systems should be running and because pressures are low enough that HPCI and RCIC turbine operation is at their limits.

At Fukushima the low pressure ECCS systems were not available due to loss of AC power so operators probably delayed depressurizing the RPV as long as they could.

Using The plots and data generated by Mr. Stolfi, (Thanks) Unit 2 RC pressure dropped to near Torus pressure after noon on 3/14 coinciding with the marked timeline labeled “Meltdown.” However the RPV level dropped below instrument zero earlier that morning so the loss of makeup occurred sometime earlier when level dropped. The length of time the operators maintained level in Unit 2 far exceeded either a 4 hour or 8 hour battery depletion time. In other words they did something right to extend the time to core damage.

Using the same plots for Unit 3, things were not so rosy. RPV level was below zero when Stolfi’s level plots start. Again Pressure for the RCIC or HPCI steam supply dropped coincident with the time marked “Meltdown” . The operator logs at Unit 3 and early TEPCO news releaeses reported problems with operation of HPCI (stopped) at 0242 on 3/13, but did not describe the problem in any detail. An hour and a half later the level was estimated to be below TAF.

 

[jim hardy]

"""If the suppression pool pressure rises to such heights that the steam flow won't move the RCIC turbine, couldn't you, as a last resort measure, vent the suppression pool into the atmosphere ? Steam engines don't need a cooling system provided you are allowed to release the steam into the atmosphere. """


I think i recall from the NRC report on extended blackout, using Brown's Ferry's specific plant design as a 'typical' example, that the RCIC steam turbine has a temperature switch to shut it down should ambient temperature reach 200F. Reason is that high ambient temperature infers a steam leak. I would guess that happened with no seawater to provide basic cooling to the plant.
http://www.ornl.gov/info/reports/1981/3445600211884.pdf
see page 63 of report, pdf page 75.

Also, the RCIC equipment is not located in a closely confined space, and
some natural convection within the reactor building will certainly occur.
Nevertheless, it is conceivable that the local temperature in the vicinity
of the steam leak detection sensors could reach 93.3°C (200°F) during RCIC
system operation after the average space temperature has increased to over
60°C (140CF). If this occurs, the resulting RCIC system isolation signal
can be overriden in the auxiliary instrumentation room and the steam sup
ply valves reopened and the turbine trip reset.

which presumes you can get into those rooms.

I never worked around a BWR - probably Nuceng knows way better than me.

old jim

 

[tsutsuji]

At around 11:57 am on July 24, water desalinations were automatically shut-downed after annunciator alarmed. From 7:19 pm on the same day, the water desalinations were restarted after switching to the spare equipment. The water injection into Reactors of Unit 1 to 3 was continued without interruption.
http://www.tepco.co.jp/en/press/corp-com/release/11072503-e.html

http://www.nikkei.com/news/latest/article/g=96958A9C93819595E0E7E2E2E78DE0E7E2E5E0E2E3E39790E0E2E2E2 however the spare equipment has only a 10 m³ / hour flow, while a 16 m³/ hour flow is required. Because there is not enough desalinated water, Tepco supplemented the tank for reactor injection with freshwater [from the dam ?]. Tepco also decided to decrease the flow injected into unit 3 from 9 m³/hour to 8 m³/hour.

http://www3.nhk.or.jp/news/html/20110725/t10014430861000.html as a result of taking water from the dam, the total amount of contaminated water is increasing.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110725_01-e.pdf diagram showing the broken down reverse osmosis system.

http://www.tv-asahi.co.jp/ann/news/web/html/210725016.html The desalinating facility trouble is resulting of a low pressure warning signal at a pump whose purpose is to wash the equipment [I guess, the backwash pump mentioned on page 2 of Tepco's diagram]. The facility has been restarted with two spare equipments resulting into treated quantity being cut by half.

http://mainichi.jp/select/weathernews/news/20110725dde007040051000c.html A pump in the sand filtration equipment stopped. The resulting flow after switching to backup equipment is about one half of the original 50 m³/ hour. [I wonder which I should believe : Nikkei's 10 m³/hour or Mainichi's about 50/2= about 25 m³/hour ? As both Nikkei and NHK report the produced quantity is not matching the needs, there must be some truth in it]

 

[zapperzero]

My understanding is that the RCIC turbine basically needs a difference of pressure. Did we reach a point when the pressure in the suppression chamber became so high that the steam flow in the RCIC turbine was not enough to move the turbine ?

Corrosion problems that were hidden by TEPCO (eventually triggering the 2002 scandal) were alsso found at Kashiwazaki in the recirculation piping. Maybe Fukushima suffered from the same issue and steam was escaping already? At least one of the units was reported to be "fogged in" very early on.

EDIT: take a look at this:
http://cnic.jp/english/newsletter/pdffiles/nit143.pdf
and this:
http://www.iasmirt.org/SMiRT17/WG01-1.pdf

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110718/0805_suiryou.html On 17 July afternoon, Tepco changed the pump that injects water into both unit 1 and unit 2 reactors. Its maximum flow rate is 20 m³/hour. On the morning of 17 July, the flow rate injected into unit 1 declined to about 3 m³/hour instead of the expected 3.8 m³/hour, ringing an alarm. The flow rate had to be ajusted again to 3.8 m³/hour. While nothing similar happened on the unit 2 line, it is the third time this sort of trouble happens at unit 1. For that reason it is believed that there is dirt in the piping to unit 1.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110725/0535_genshiro.html Three days ago (22 July) the flow rate into unit 2 declined to 3.4 m³/hour and to 3.2 m³/hour on 23 July. On 24 July, the flow rate into unit 1 declined to 3.3 m³/hour. This makes 3 flow decline incidents over the past three days. Each time Tepco adjusted the pump in order to recover the original flow rate. Tepco is reinforcing surveillance and investigating the cause.

 

[NUCENG]

"""If the suppression pool pressure rises to such heights that the steam flow won't move the RCIC turbine, couldn't you, as a last resort measure, vent the suppression pool into the atmosphere ? Steam engines don't need a cooling system provided you are allowed to release the steam into the atmosphere. """


I think i recall from the NRC report on extended blackout, using Brown's Ferry's specific plant design as a 'typical' example, that the RCIC steam turbine has a temperature switch to shut it down should ambient temperature reach 200F. Reason is that high ambient temperature infers a steam leak. I would guess that happened with no seawater to provide basic cooling to the plant.
http://www.ornl.gov/info/reports/1981/3445600211884.pdf
see page 63 of report, pdf page 75.

which presumes you can get into those rooms.


I never worked around a BWR - probably Nuceng knows way better than me.

old jim

You are correct, at least for BWRs here in the US. Standard Emergency Operating Procedures for BWRs include defeats to bypass both the low steamline pressure and room high temperature isolations for the RCIC system. There is no need to enter the room to activate these defeats as they are performed in control cabinets outside of the room. SBO procedures also include steps to open doors and install blowers to ventilate the room.

 

[tsutsuji]

Fukushima Daichi:

http://www.yomiuri.co.jp/science/news/20110725-OYT1T00933.htm IAEA director general Yukia Amano visited Fukushima Daiichi today : "The water treatment system's efficiency is pretty good for a performance without rehearsal".

I don't remember if the following article was already mentioned in this thread :

A former senior Tepco executive involved in the decision-making says there were two main reasons for removing the cliff. First, a lower escarpment made it easier to deliver heavy equipment used in the plant, such as the reactor vessels, turbines and diesel generators, all of which were transported to the site by sea. Second, the design of the plant required seawater to keep the reactor cool, which was facilitated by a shorter distance to the ocean.
12 July "Fateful Move Exposed Japan Plant: Tokyo Electric Lowered Elevation of Land Before Building Nuclear Facility, Weakening Tsunami Defense" http://online.wsj.com/article/SB10001424052702303982504576425312941820794.html

Tsuruga nuclear power plant unit 2:

fuel rod damage
http://www.fukuishimbun.co.jp/localnews/nuclearpower/29540.html (25 July) Japco released the result of the analysis of the 193 fuel assemblies from Tsuruga unit 2 reactor which was manually shut down in May after the discovery of radioactive substances in the cooling water. A leak was found in one assembly first loaded in August 2006. As the fibroscopy revealed no surface damage or abnormality with a 0.025 mm accuracy, it is thought that the leak occurs through random tiny pinholes. That assembly will no longer be used. Including this one discovered at Tsuruga, 5 out of 2,450,000 fuel rods of the same type used in Japan have been found with pinholes until now.

http://www.japc.co.jp/news/bn/h23/230725.pdf 25 July press release. Page 2 : fuel assembly sipping test. Page 3 : visual inspection (no abnormality revealed) - ultrasonic test to detect the presence of water inside the leaking rod - examples of fibroscopy pictures.
http://www.japc.co.jp/news/bn/h23/230506.pdf 06 May press release (reactor shutdown announcement)
http://www.japc.co.jp/news/bn/h23/230502.pdf 02 May press release (increase of radioactive substances in primary coolant water)

atmospheric release
http://www.47news.jp/CN/201107/CN2011072501000850.html On 8 May and on 21 May, very small quantities of radioactive gasses were released into the atmosphere through the exhaust stack.

http://www.japc.co.jp/tsuruga/news/info/20110509_tsuru2_haikitougasmoinita_joushou.html (http://www.japc.co.jp/tsuruga/news/pdf/110509_tsuru2__haikitougasmoinita_joushou.pdf) 9 May press release : 4.1 10^{9} Bq were released. This is 400,000 times less than the yearly limit of 1.7 10^{15} Bq for noble gasses.

http://www.japc.co.jp/tsuruga/news/info/20110521.html (http://www.japc.co.jp/tsuruga/news/pdf/110521tenpuzu.pdf) 21 May press release : 8.1 10^{9} Bq were released. This is 200,000 times less than the yearly limit of 1.7 10^{15} Bq for noble gasses. (yearly release in 2008 : below detection threshold ; yearly release in 2009 : 7.4 10^{8} Bq).

http://www.japc.co.jp/tsuruga/news/info/20110712_1.html (http://www.japc.co.jp/tsuruga/news/pdf/20110712_1.pdf) 12 July press release about the atmospheric release causes and countermeasures.

fire
http://www.japc.co.jp/tsuruga/news/pdf/110518_tsuru2_gensuitanku_sagyoujino_hakka.pdf (18 May) a small fire broke out and was extinguished with a fire water bucket during anti-earthquake reinforcement work on the top of a freshwater tank (source for secondary coolant water or fire extinguishing purposes). A penetrant testing spray can was ignited during welding or grinding. Nobody was injured. There is no environmental consequence.

Tsuruga nuclear power plant unit 1 (under inspection since January) :

http://sankei.jp.msn.com/affairs/news/110712/dst11071221510025-n1.htm (12 July) A chemical (such as sulphuric acid) leaked from two locations on a pipe belonging to a liquid waste tank. On 18 June a worker found the leak with the chemical solidifying into an ice-lump like shape and a dried drop on the floor. The pipe will be changed. It had never been inspected since its installation in 1977. This is a very small radioactive leak inside the facility without consequence on the environment.

http://www.japc.co.jp/tsuruga/news/pdf/20110712_2.pdf 12 July chemical leak press release with pictures. The leak is located in the New waste treatment building.

The No. 1 reactor at the Tsuruga nuclear power plant in Fukui Prefecture does not have a vent to release excess pressure during a reactor emergency
4 July http://search.japantimes.co.jp/cgi-bin/nn20110704a2.html

 

[Atomfritz]

It is really sad that the big Hamaoka NPP probably will have to be dismantled due to bad siting even in spite of costly tsunami retrofitting.
I am sure it would have been way cheaper in the long run if they had been built on suitable sites with adequate quake/flood protection.

Anyway, reactors shouldn't be housed in cardboard boxes that pop open due to small hydrogen fireworks imho.

Corrosion problems that were hidden by TEPCO (eventually triggering the 2002 scandal) were alsso found at Kashiwazaki in the recirculation piping. Maybe Fukushima suffered from the same issue and steam was escaping already? At least one of the units was reported to be "fogged in" very early on.

Thanks for the links!

I agree with the conclusion of the CNIC writer.
This scenario is truly an unsolved safety risk, as quite a lot of the welds cannot be checked anymore after reactor went into operation.
In fact the safety estimates for life extensions are just guesses based on the correctness of old Tepco data. And so it's all some sort of gambling.

By the way, in the http://cnic.jp/english/newsletter/pdffiles/nit142.pdf" I found something that I didn't know of before.
Quote from pg. 8:
・The reactor buildings and turbine buildings for KK-1 to 7 have continued to rise and sink erratically
・The exhaust stacks are leaning to the side due to tilting of the foundations. This is most prominent at KK-1, 2 and 3

The Leaning Tower of Kashiwazaki-Kariwa:

This and Fukushima really could become big tourist attractions!

Edit:

Tsuruga nuclear power plant unit 1 (under inspection since January) :

http://sankei.jp.msn.com/affairs/news/110712/dst11071221510025-n1.htm (12 July) A chemical (such as sulphuric acid) leaked from two locations on a pipe belonging to a liquid waste tank. On 18 June a worker found the leak with the chemical solidifying into an ice-lump like shape and a dried drop on the floor. The pipe will be changed. It had never been inspected since its installation in 1977. This is a very small radioactive leak inside the facility without consequence on the environment.

http://www.japc.co.jp/tsuruga/news/pdf/20110712_2.pdf 12 July chemical leak press release with pictures. The leak is located in the New waste treatment building.

Possibly the visual inspections, if any, were also very superficial. The waste safety seems not to be taken as serious as necessary, no matter where on the world.
More than third of a century without thorough inspection... mad!
Probably the nuclear industry needs a civil SFP Kyshtym to wake up...

 

[tsutsuji]

・The exhaust stacks are leaning to the side due to tilting of the foundations. This is most prominent at KK-1, 2 and 3

The Leaning Tower of Kashiwazaki-Kariwa:

This and Fukushima really could become big tourist attractions!

Let alone potential http://en.wikipedia.org/wiki/Distortion_%28optics%29" , an unidentified and undated picture of Kashiwazaki Kariwa's units 5-6-7 is a rather weak evidence of leaning being "most prominent at KK-1, 2 and 3".

The following picture of units 5-6-7, dated 18 June 2008 : http://www.flickr.com/photos/27893064@N06/2853437602/in/photostream is showing the same stack, but leaning the opposite way. In my opinion this is nothing more than photographic distortion.

Here is a picture dated 3 April 2011 http://ja.wikipedia.org/wiki/ファイル:Kashiwazaki-Kariwa_Nuclear_Power_Plant.jpg where all stacks seem vertical.

 

[MiceAndMen]

By the way, in the http://cnic.jp/english/newsletter/pdffiles/nit142.pdf" I found something that I didn't know of before.
Quote from pg. 8:
・The reactor buildings and turbine buildings for KK-1 to 7 have continued to rise and sink erratically
・The exhaust stacks are leaning to the side due to tilting of the foundations. This is most prominent at KK-1, 2 and 3

The Leaning Tower of Kashiwazaki-Kariwa:

This and Fukushima really could become big tourist attractions!

The linked newsletter does mention those points on page 8, but that photo does not appear in the newsletter at all. What that photo displays IMO is nothing more than optical distortion.

 

[Atomfritz]

Let alone potential http://en.wikipedia.org/wiki/Distortion_%28optics%29" , an unidentified and undated picture of Kashiwazaki Kariwa's units 5-6-7 is a rather weak evidence of leaning being "most prominent at KK-1, 2 and 3".

You are right, this photo is not really suitable as proof.
It is in fact a very small part of http://2.bp.blogspot.com/_b5hcKABPlGI/RqA9vnjdshI/AAAAAAAAD2s/72ODBAMI9zc/s1600-h/0712l.jpg".
I didn't find a map with a legend what unit stands where, so I supposed the smaller ones are the older ones.

 

[LabratSR]

http://www.ornl.gov/info/reports/1981/3445600211884.pdf

Interesting to note that Sherrell Greene, from the interview I posted above, is one of the authors of this document.

 

[Atomfritz]

Corrosion problems that were hidden by TEPCO (eventually triggering the 2002 scandal) were alsso found at Kashiwazaki in the recirculation piping. Maybe Fukushima suffered from the same issue and steam was escaping already? At least one of the units was reported to be "fogged in" very early on.

EDIT: take a look at this:
http://cnic.jp/english/newsletter/pdffiles/nit143.pdf
and this:
http://www.iasmirt.org/SMiRT17/WG01-1.pdf

Let's go back to the central point of the article published in the CNIC newsletter you linked at.
It's written by an ex-RPV designer and looks very competent to me.

The "unsolved safety problem" (as at least NRC etc name it) that this man describes explains the phenomenon of the high D/W pressure very well. Remember, it was almost double of planned maximum pressure.
His explanation also might also give a good picture why so much hydrogen leaked outside primary containment.

The crucial point that the nuclear industry does not want people to know is that the accident possibly was caused by primary containment tube break, and not by the tsunami.

To understand this, look at this picture from page 3 from http://cnic.jp/english/newsletter/pdffiles/nit115.pdf" :

(for higher res image please use source link)

You see, 1F1 embrittlement has already been very high.

Now consider the combination of earthquake stress, embrittlement and another important factor, metal thinning, that the nuclear industry does not like to talk about.

Look at this picture:

(http://cnic.jp/english/newsletter/pdffiles/nit103.pdf" )
This tube ruptured in the Mihama-3 accident that fried 11 workers with hot high-pressure steam, four of them dying.
Quotes from accident reports:

"A main condensate pipe in the secondary coolant system had ruptured. The pipe contained water heated to 140 degrees Celsius under 9.5 atmospheres pressure. When the pipe ruptured, this water spewed out in the form of steam, severely scalding the unfortunate workers who happened to be in the room. The thickness of the wall of the pipe at the point where it ruptured was down to around 1mm, compared to the original thickness of 10mm and the regulatory minimum of 4.7mm. It had never been checked during the entire 28 years that the plant had been operating"
​

(highlighting by me, source: http://cnic.jp/english/newsletter/pdffiles/nit102.pdf" )

Official analysis (http://cnic.jp/english/newsletter/pdffiles/nit106.pdf" ) says:

"Final Reports on Mihama-3 Accident:
...The NISA and NSC reports both fail to answer the questions of when KEPCO became aware that the pipe had not been inspected, when it became aware that some locations had not been included on the inspection list, and whether remaining life expectancy assessments had been made."​

Maybe there are many more never-visited locations in the NPPs that never have been inspected since inauguration and we only see tip of iceberg.

There is just one thing for sure:
The nuclear industry obviously doesn't want people to know of aged, brittle and thin-walled reactors that are in permanent danger of bursting open due to a plethora of possible causes.

In Germany already some old reactors had to be retrofitted with ECCS water preheating, just to avoid the RPV eventually bursting only because of using "normal" ECCS with unheated water.

 

[tsutsuji]

http://news24.jp/articles/2011/07/14/07186434.html and http://news.tbs.co.jp/newseye/tbs_newseye4775950.html ( ) [14 July] The new water treatment facility, called "[SARRY]" left Yokohama Port this morning. Its start is planned for next month. [SARRY] is made by Toshiba, IHI and US company Shaw. Its decontamination factor is up to one million. According to Toshiba, it can be used as a backup of the Kurion-Areva system.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110726/0535_shinsouchi.html I have no definite proof that it it the same ship or exactly the same shipment or why it made a call at Onahama Port if it is the same ship, but the first of two shipments of cylindrical tanks for the new SARRY system left Onahama Port yesterday evening and it is planned to arrive at Fukushima Daiichi today. SARRY consists of 14 cylindrical tanks filled with a cesium filtering mineral inside. It can be used either in parallel or in combination with the other system.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110726/0530_sekkeimiss.html The desalination facility's trouble was the consequence of a pump setting mistake based on a wrong assumption of a tank water level. The system fully recovered at 01:00 AM this morning after correcting the wrong setting.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110726/index.html At 09:30 PM yesterday, a worker found out that 1 out of 4 Kurion system pumps was down. That pump was restarted 30 minutes later. Tepco has no idea when it stopped. This incident had no consequence on the cooling of reactors.

http://www.flickr.com/photos/iaea_imagebank/5765318454/sizes/l/in/photostream/ a large size picture of the unit 5-6 water intake collapsed crane. The triangle structure behind the truck is the crane's http://www.houseoffoust.com/fukushima/tepco_pics/r6_waterpump4.jpg broken leg which could not be seen on http://www.netimago.com/image_202944.html .

 

[tsutsuji]

You are right, this photo is not really suitable as proof.
It is in fact a very small part of http://2.bp.blogspot.com/_b5hcKABPlGI/RqA9vnjdshI/AAAAAAAAD2s/72ODBAMI9zc/s1600-h/0712l.jpg".
I didn't find a map with a legend what unit stands where, so I supposed the smaller ones are the older ones.

The unit numbers from south to north (or looking at the sea) are 1-2-3-4-7-6-5. A map is available on page 5 (pdf page number 6) of http://www.nsc.go.jp/senmon/shidai/shisetsuken/shisetsuken057/siryo4.pdf .

I found the following :

http://www.nsc.go.jp/senmon/shidai/shisetsuken/shisetsuken057/siryo4.pdf Tepco report, dated 13 December 2010, presenting the results of the inspection of Kashiwazaki Kariwa unit 3 exhaust stack.

On page 13 (pdf page number 14) they say they use the standard set by the Architectural Institute of Japan for the assessment of the damages of the 1995 Kobe earthquake. According to that standard, the maximum allowed inclination for unit 3 stack is 1/300 and the maximum allowed sinking is 50 mm.

On page 15 (pdf page number 16) they say they measured a 1/2200 inclination and a maximum sinking of 13.9 mm, therefore the standard is satisfied.

Cracked foundation piles
KK-3's exhaust stack has 52 foundation piles. Only four of these have been checked and cracks were found in all four. The biggest crack was 2mm wide and 2.08mm long. Kotaro Kuroda, a member of the subcommittee on equipment integrity and seismic safety, suggested that this should be assessed as level IV damage, but TEPCO assessed it as level II on the grounds that there was no exfoliation. One wonders about the condition of the other foundation piles. Clearly they should be checked.

http://cnic.jp/english/newsletter/nit140/nit140articles/kk.html or page 2 http://cnic.jp/english/newsletter/pdffiles/nit140.pdf jan/feb 2011 ; the 2mm wide and 2.08mm long crack data are available on page 16 (pdf page number 17) of http://www.nsc.go.jp/senmon/shidai/shisetsuken/shisetsuken057/siryo4.pdf

http://www.tepco.co.jp/nu/material/files/k09071501.pdf report dated 15 July 2009 about the unit1-unit2 exhaust stack. Page 4-6 (pdf page 12) : The measured inclination (1/2000) and the sinking (16.8 mm) are both satisfying the standard.

http://www.nsc.go.jp/senmon/shidai/shisetsuken/shisetsuken032/ssiryo3.pdf　report dated 7 December 2009 about unit 5 exhaust stack. Page 4-6 (pdf page 12) : inclination 1/13,000 and sinking 2.3 mm.

http://www.nsc.go.jp/senmon/shidai/shisetsuken/shisetsuken008/siryo8.pdf 10 October 2008 report on the inclination of buildings. The worst one is unit 6 control room, with 1/4000 but this is below the 1/2000 standard applying to those buildings (pages 2 and 3 - pdf page numbers 3 and 4).

http://www.tepco.co.jp/nu/material/files/g08071003.pdf Pages 4 and 5 (pdf page numbers 5 and 6) show the damages to two lightning attraction towers' diagonal bracing.

 

[MJRacer]

_

I am not impressed with CNIC's sourcing practices. Reading some of the linked reports, there are multiple unsourced references. The http://cnic.jp/english/newsletter/pdffiles/nit103.pdf publication which reports on the Mihama pipe rupture as mentioned above is one example. I have tried to source the diagram of the pipe thinning and I believe that I have found what may be the original source document from which this image was created. Please see http://www.atomdb.jnes.go.jp/content/000025568.pdf , page 66. It looks like the image in the CNIC document of the cross-section of piping may have been created by combining 2 or more of the images on that page. Lack of sourcing lowers credibility, IMHO. In this case, though, I may have found the source.

The Alaska pipeline has been "pigged" using smart pigs more than 60 times. Smart pigs use Ultrasonic Transducing, Magnetic Flux Leakage Detection and Curvature detection on the Alaska pipeline. Please see http://www.dec.state.ak.us/spar/perp/response/sum_fy11/110108301/factsheets/fact_Pigging.pdf.

Pipelines are specifically designed to be pigged. I am not sure that Nuclear Power Plants, however, are so designed (I don't think smart pigs were in existence when some of these plants were built). In principle, pigging using smart pigs permits 100% inspection of the full length of piping, especially critical piping that may not be easily accessible. Obviously, implementing a pigging program in a plant that was not designed for it would present a number of challenges. Among them would be I would think radiation hardening (smart pigs are electronic devices), launching/retrieval issues, fittings that might prevent passage of the pigs and so forth. Does anyone know if this has been tried in practice?

 

[joewein]

I had always assumed the roof had come off the roof girders in unit 4 at the same time the panels were blown out, but apparently not so. http://www.isis-online.org/isis-reports/detail/new-satellite-image-of-fukushima-daiichi-nuclear-site-in-japan-from-march-1/" shows the damaged building but with the roof girders still covered.

 

[westfield]

I had always assumed the roof had come off the roof girders in unit 4 at the same time the panels were blown out, but apparently not so. http://www.isis-online.org/isis-reports/detail/new-satellite-image-of-fukushima-daiichi-nuclear-site-in-japan-from-march-1/" shows the damaged building but with the roof girders still covered.

It's seems to be an illusion because there are quite a few March 16 shots that show "normal" Unit #4. (that reads like a tepco press release - yes , the roof is still not there so Unit 4 is nominal.)

Like this capture from the March 16 SDF Chopper footage - source tepco.

 

[joewein]

It's seems to be an illusion because there are quite a few March 16 shots that show "normal" Unit #4. (that reads like a tepco press release - yes , the roof is still not there so Unit 4 is nominal.)

Like this capture from the March 16 SDF Chopper footage - source tepco.

The image I came across may have been right at the margin of the satellite camera resolution. Here's best version of the DigitalGlobe image I could find:

http://upload.wikimedia.org/wikipedia/commons/7/7d/Fukushima_I_by_Digital_Globe.jpg

 

[Bandit127]

2 videos of International Atomic Energy Agency (IAEA) head, Yukiya Amano visiting Fukushima Daiichi.

The first is an interview against a backdrop of workers being assessed for contamination.
http://www.youtube.com/watch?v=cX_0VYScSms&feature=relmfu"

The second (over 6 minutes) is of a plant tour.
http://www.youtube.com/watch?v=bA1jojWGt4k&feature=relmfu"