Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[tsutsuji]

Edit:
They operate part of Yonomori 1 line at 6kV, using a portable transformer (see Work 3,4,9) to transform from 66 to 6.
Maybe because in March the roads were in no shape to transport a big transformer on a truck convoy?
I am still guessing why they did this. Maybe it was the fastest way to get a handy low voltage to operate with?

On pages 64 and 65 of http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110525_01-e.pdf , there are a few explanations on the different power voltages used at the plant. The diesel generators supply 6.9 kV, and some equipments can use this 6.9 kV directly. Then the voltage is lowered to 480 V for some other equipments. Some yet other equipments use DC 125 V.

I wonder if they actually mean 6.9 kV when they write 6 kV or if they mean exactly 6.0 kV.

 

[Atomfritz]

I think the doublr slash is a cable failure and the dots show repair connections.

In electrical engineering the double slash means "line cut". Didn't ever find an other meaning, even though schematics are drawn differently around the world.

No matter whether for revision, modification etc.
Just my 2 ct, as my profession is electronics engineering and when dealing with apparatuses you always have to keep in mind what version they are of.

@ tsustsuji-san:
Thank you for the links!
I have to admit that I didn't see these detailed pics before. This damage on Shin-Fukushima really shocks me. (Please don't misunderstand me, in Germany we know such damage only from former foreign bomb raids...) I really have to sleep over all this information before I can digest it and get clear thoughts about the whole thing.

Edit:

The diesel generators supply 6.9 kV, and some equipments can use this 6.9 kV directly. Then the voltage is lowered to 480 V for some other equipments. Some yet other equipments use DC 125 V.

I wonder if they actually mean 6.9 kV when they write 6 kV or if they mean exactly 6.0 kV.

In fact this is not very important due to the tolerances. Under-overvoltages of +-20% are usually of no problem. So you usually can supply a 6kV transformer primary with 7kV without noticing an adverse effect on the secondary (except higher consumption and wear), and vice versa.

 

[jim hardy]

this is more trivia, but it helps one's thought processes to not let these little questions pile up unanswered for they chip away at our confidence.

so i'll cast a little light on this one:
"I wonder if they actually mean 6.9 kV when they write 6 kV or if they mean exactly 6.0 kV. "


4160 and 6900 volts are two very common standard voltages. With higher voltage you need less copper but better insulation. As plant designs require ever bigger motors the wire sizes required become unmanageably big. Biggest motor in my plant was 7,000 hp and we were 4160, those wires looked like firehoses. They are difficult to install and copper is today ~ $4 a pound.It's almost certain they are referring to nominal 6.9kv equipment. We tend to name things colloquially, 4kv and 6kv is how we referred to ours though 7kv would have been more accurate.

The tolerance Atomfritz mentioned is important to the plant. We have to float up and down a few percent according to system load.
Power company tries to deliver constant voltage to the customer. On days with high demand the plants will raise their voltage a bit to overcome voltage loss in the transmission wires & transformers, and on easy days lower voltage somewhat. That's all directed from a central system control office.

We always said "Our in-plant power is not nearly so stable as what the customer sees".

old jim

http://www.resourcesaver.com/file/toolmanager/O105UF493.pdf

 

[Lambert]

oh oh

http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/usc0004sg6.php

http://www.vancouversun.com/news/Quake+jolts+northeast+Japan+nuclear+workers+evacaute/5079075/story.html

 

[Gary7]

Was about a magnitude 4 (Japanese scale) in Fukushima. Fukushima Daiichi reported no damage as a result of this quake. Tsunami was about 10 centimeters in Fukushima.
Tsunami alert has been lifted.

 

[joewein]

Was about a magnitude 4 (Japanese scale) in Fukushima.

The Japanese "shindo" scale is usually translated as "intensity" or "seismic intensity" in English (you don't say "magnitude" unless you mean the Western scale that measures energy released, which is sometimes incorrectly referred to as "Richter scale").

It's listed as M7.1 here:
http://www.jma.go.jp/en/quake/20110710100736491-100957.html

That's almost 1000 times less energy than the M9.0 quake on March 11. I still felt it here in Tokyo and it was fairly long but quite weak here, unlike 3/11. Only half of my family noticed it at all.

 

[tsutsuji]

Edit:
They operate part of Yonomori 1 line at 6kV, using a portable transformer (see Work 3,4,9) to transform from 66 to 6.
Maybe because in March the roads were in no shape to transport a big transformer on a truck convoy?
I am still guessing why they did this. Maybe it was the fastest way to get a handy low voltage to operate with?

So this 6kV is another name for the 6.9 kV which they need at the plant. You need to lower that 66 kV into this 6 or 6.9 kV some way or other. My guess is that they wanted to work as far away from the plant as possible, rather than risk the workers' lives in a contaminated plant where hydrogen explosions occur every couple of days.

Was about a magnitude 4 (Japanese scale) in Fukushima. Fukushima Daiichi reported no damage as a result of this quake. Tsunami was about 10 centimeters in Fukushima.
Tsunami alert has been lifted.

http://mainichi.jp/select/jiken/news/20110710k0000e040029000c.html During the tsunami alert, workers evacuated the area close to the sea and the megafloat filling operation was stopped.

[URL]http://www.tepco.co.jp/en/news/110311/images/110710_1t.jpg[/URL]
http://www.tepco.co.jp/en/news/110311/images/110710_1.jpg

It had been a long time since they last had a trouble at the water treatment facility.

http://www.jiji.com/jc/c?g=soc_30&k=2011071000054 : It had to stop at 4:50 AM because of a chemical leak at the Areva facility. A green coloured chemical burst out at the junction of the chemical hose and the (contaminated water?) pipe. The amount leaked is 50 l. The chemical is not poisonous but some contaminated water could have leaked too. It is the first trouble since 30 June.

http://mainichi.jp/select/jiken/news/20110711k0000m040021000c.html the leak was viewed on a surveillance camera at 4:53 AM. The facility was started again at 5 PM after the junction was changed for a cast iron one. The leaked liquid's radiation was 5500 Bq/cm³ of Cs-137 which is a normal radiation at the entrance of the Areva system and a hint that contaminated water flowed backwards through the leak. Tepco is studying what to do with another similar junction located elsewhere in the facility, beyond a visual inspection showing it is not leaking. The megafloat filling will start again on 11 July.

http://www.asahi.com/national/update/0708/OSK201107080148.html In a symposium in Tokyo, Kyoto university reseachers presented a water decontamination method they claim is cheaper and faster, and produces less waste than the one used at Fukushima Daiichi. It is based on the flotation method used in the mining industry. You add Fe or Ni, and chemicals that help separate Cs from water and precipitate the Cs. Then you add bubbles from the bottom, and the Cs rises to the surface with the bubbles. Then you skim the foam. Their tests with 5 different contaminants show that more than 99% can be removed.

 

[Bioengineer01]

It appeared that the screwup that I had discovered had never made it to the top bosses because nobody wanted it known that it was a problem that was easily corrected with people doing their jobs in an attentive fashion.

Joe, I have been in several situations similar to what describe but in the pacemaker/defibrillator industry of medical devices. And always the screw-ups got to the top the bosses, but never in writing (so that they could deny knowing), but never to the board of Directors, because it would have made them look bad. It is possible that your fix was known by your top brass, but that they had already told the board that it was a system problem and had already requested approval for the expenditure for the new system.

 

[Bioengineer01]

It is this human nature issuer you describe that makes me question the safety and wisdom of nuclear reactors, situated close to population centers and valuable real estate.

I did a back of the envelope reliability analysis similar to those we do for medical devices and calculated what is the reliability level that the worst Nuclear Power Plant (and associated systems, like power lines) should have to have a 99% probability level that NO nuclear plant will have a catastrophic failure in the next 30 years. The number is scarely close to 100%. I am not a reliability person, but if you know of anybody, please invite him/her to destroy my guestimates here. When I brought that system reliability number down, it very quickly trended to 100% probability of one catastrophic failure every thirty years...

 

[Bioengineer01]

The reaction of worldwide nuclear community up to now is mostly PR. PR is not going to convince me. I need to see deeds, not words.

"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled", said Richard Feynman, and I fully agree with him.

I completely agree with Nikkom perspective. It is unbelievable how close the analogy is to implantable medical devices too. Where the shuttle accident reports were evaluated in detail and lessons learned. Sadly the reality always was that before the money was invested, every lesson was used correctly and the burden of proof was on the engineers to prove it was safe, but after the product was launched commercially, then the burden of proof was shifted to "prove to me it is unsafe". Most recalls in the implantable medical device industry have been made a lot worse by this behavior. NPPs are in the post commercial launch situation and thus the mentality is prove it is unsafe before I do something. That is not the mentality of the patient that has the device or the public that will suffer the consequences of failure.

 

[NUCENG]

I completely agree with Nikkom perspective. It is unbelievable how close the analogy is to implantable medical devices too. Where the shuttle accident reports were evaluated in detail and lessons learned. Sadly the reality always was that before the money was invested, every lesson was used correctly and the burden of proof was on the engineers to prove it was safe, but after the product was launched commercially, then the burden of proof was shifted to "prove to me it is unsafe". Most recalls in the implantable medical device industry have been made a lot worse by this behavior. NPPs are in the post commercial launch situation and thus the mentality is prove it is unsafe before I do something. That is not the mentality of the patient that has the device or the public that will suffer the consequences of failure.

I do not understand how any progress can be made without some risk. What do you want? It would be wonderful if new technologies like medical implants, or space exploration, or nuclear power, or anything else you care to name could be born without any potential for errors or flaws, or unconceived risks, but can you name one development that has? The logical consequence of what you just wrote is that we can never do anything new. Doctors should tell people they are going to die because we never could risk reactions to vaccines or medications, or surgery or any of the thousands of medical developments that came before implants.

The Black Plague did not end urbanization. The Titanic did not end shipbuilding. The Hindenberg did not stop commercial aviation. The Tacoma Narrows did not end bridge building. Louis Washkansky's death did not stop medical science from trying to correct heart disease. The Challenger has not ended Space exploration.

The burden on engineers (and doctors) is to find solutions to problems. It is impossible to prove that anything is "safe." In solving problems they have to balance benefits and risks. Society has to agree with that assessment of benefit and risks or the engineers work will never be built. The job doesn't stop there. A technology must be proved over time, and adapted, updated, and improved.

Your analogy is inappropriate, your logic is absent, and your conclusion is dead wrong. The standard you are trying to demand would halt all progress, including development of solar and wind power generation. (Electricity has risks all by itself, whatever the source.)

 

[zapperzero]

The Black Plague did not end urbanization.

Gentlemen, methinks it's time to take this to the political thread?

 

[NUCENG]

Gentlemen, methinks it's time to take this to the political thread?

I agree.

 

[Gary7]

Another layman's question: Assuming meltdown of a portion of the fuel (or most/all of the fuel) in the reactors of Fukushima Daiichi #1, #2, and #3, what condition could we expect the corium to be in after 2+ months of cooling. Is there a possibility that the various fuel masses have completely solidified by now, or would the center still be liquid/molten?

Clarification: Let me say that I understand the heat comes from decay of the fission products, and that even if water is continually poured onto it, it will continue to generate heat for years. I suppose what I am asking is whether or not the addition of steel, concrete, zirconium, etc... will enable the corium to solidify (or to form a crust that is sufficiently deep that it ceases to pose a problem with regard to moving around the underside of what is left of the reactors).

 

[Caniche]

60 ton lumps enriched to 5%,

 

[Bioengineer01]

I think there's been some interest, just not many comments. I, for one, haven't yet found the time to do much more than a quick skim-through.

EDIT: the idea of printing out e-mails, then collating them in a scanned PDF? Who came up with that one? There's zero excuse here - while I can understand why rules and regulations would have treeware master copies, this is just stupid, verging on willfully incompetent.

If I sound frustrated, it's 'cause I am. I have good text processing, indexing and search tools at my disposal - and none of them work!

In the past (10 years ago +) I have used very successfully OCR programs that can read pdf files and output a pdf file with a built-in searchable text layer. Extremely useful when building a database with pdf files.

 

[etudiant]

Another layman's question: Assuming meltdown of a portion of the fuel (or most/all of the fuel) in the reactors of Fukushima Daiichi #1, #2, and #3, what condition could we expect the corium to be in after 2+ months of cooling. Is there a possibility that the various fuel masses have completely solidified by now, or would the center still be liquid/molten?

Clarification: Let me say that I understand the heat comes from decay of the fission products, and that even if water is continually poured onto it, it will continue to generate heat for years. I suppose what I am asking is whether or not the addition of steel, concrete, zirconium, etc... will enable the corium to solidify (or to form a crust that is sufficiently deep that it ceases to pose a problem with regard to moving around the underside of what is left of the reactors).

If we assume that all of the core is neatly collected into one lump, we have a blob that needs to dissipate somewhere around 5 megawatts continuously to stay in a steady state. Water has a latent heat of vaporization of about 2000 joules/gm, so we need to vaporize about 2.5 kg of water every second, or about 9 tons/hr. Do note that this is boil off, although it may re condense in the water flooding the plant.
That is about the rate at which the reactors are getting fed, so we have a measure of stability.

However, that says nothing about the state of the fuel, except that if it were still a superhot melt the vapors given off from the reactors would show some of the chemical dissociation products. However, TEPCO has been only modestly informative about the reactor airborne emissions and I've no competence to assess that which they have released. Because no one expert has raised any alarm, I assume the fuel is largely immobile, while still in dire need of continuous cooling.

 

[robinson]

Wouldn't any melted spent fuel also be an issue? Seems like at least one fuel pool is steaming away as well.

 

[etudiant]

Wouldn't any melted spent fuel also be an issue? Seems like at least one fuel pool is steaming away as well.

The spent fuel does need cooling as well, but normally a cooling circuit keeps the refrigeration going.
Afaik, that has been restored at the SFPs for reactors 1-3, but is still not there for reactor 4, because the explosion blew out part of the cooling pipes. They have been able to access an essential valverecently and expect to be able to restore cooling to SFP 4 as well. TEPCO hopes to wrap up that work this month.

 

[joewein]

If we assume that all of the core is neatly collected into one lump, we have a blob that needs to dissipate somewhere around 5 megawatts continuously to stay in a steady state. Water has a latent heat of vaporization of about 2000 joules/gm, so we need to vaporize about 2.5 kg of water every second, or about 9 tons/hr. Do note that this is boil off, although it may re condense in the water flooding the plant.
That is about the rate at which the reactors are getting fed, so we have a measure of stability.

On June 1 the remain decay heat output in unit 1 was 3.7 MW while in units 2 and 3 it was 6.3 MW, which is 0.26% of thermal output at shutdown. Over the next 8 months that will go down to 0.21% of thermal output at shutdown, so it's essentially steady now (http://mitnse.com/2011/03/16/what-is-decay-heat/" ), since most of the iodine-131 and other shortlived isotopes are largely gone.

Water injection in units 1 and 2 is currently running at 3.5 t/h, while unit 3 is receiving 9 t/h, even though unit 2 and 3 should have the same decay heat output. If all the heat was being dissipated by boiling they would consume the same amount of water. Unit 3 is receiving more water because measured temperatures at the lower end of the RPV were higher.

If temperatures in unit 2 are lower despite only receiving 1/3 of the amount of water, perhaps most of the fuel there has already left the RPV and has splashed onto the containment concrete floor. Alternatively, the shape of the corium may obstruct water flow in the RPV of unit 3, so water boils on top of it but doesn't flow past it.

Units 2 and 3 should be largely identical, except that unit 3 was more recently refueled and therefore the average burn-up rate of its fuel should be lower, hence there should be marginally *less* decay heat output in unit 3 than unit 2.

60 ton lumps enriched to 5%,

Unit 1 had 68 t fuel enriched to 3.4% while unit 2 and 3 had 94 t enriched to 3.6%.

 

[joewein]

Wouldn't any melted spent fuel also be an issue? Seems like at least one fuel pool is steaming away as well.

The fact the pool is steaming shows that it has water in it, which is good. If they got the heat exchanger hooked up, it would be even better of course.

The spent fuel pool with the most active fuel and cause for the biggest worries was unit 4, but radioactivity levels there are much lower than in the reactor building (R/B) basement water:

Unit 4 SFP: 123 Bq/cm3 (Cs-134 + Cs-137)

Unit 1 R/B: 250,000 Bq/cm3 (Cs-134 + Cs-137)
Unit 2 R/B: 6,100,000 Bq/cm3 (Cs-134 + Cs-137)
Unit 3 R/B: 3,100,000 Bq/cm3 (Cs-134 + Cs-137)

This is why TEPCO doesn't believe in major fuel damage in the #4 SFP.

Its radioactivity levels are also orders of magnitudes lower than in the #1 through #3 SFPs.

Unit 1 SFP: 26,000 Bq/cm3 (Cs-134 + Cs-137)
Unit 2 SFP: 191,000 Bq/cm3 (Cs-134 + Cs-137)
Unit 3 SFP: 290,000 Bq/cm3 (Cs-134 + Cs-137)

Number three has the worst numbers, perhaps because it had that big blast. It is the one with lots of concrete and steel on top of the fuel assemblies seen in http://www.youtube.com/watch?v=KugIrnThul0" (you don't actually see the fuel, except for a single handle sticking out).

 

[tsutsuji]

Under the timeline, nuclear fuel will be removed from the pools for spent fuel at the No. 1 to 4 reactors starting in fiscal 2014. Officials hope to finish removing such fuel from the first reactor by fiscal 2016.
http://mdn.mainichi.jp/mdnnews/news/20110711p2a00m0na003000c.html

http://www.tv-asahi.co.jp/ann/news/web/html/210710029.html Picture of the repaired hose fitting at the water treatment facility.

http://www.nikkei.com/news/category...39797E3E2E2E2;at=DGXZZO0195165008122009000000 Tepco is going to repair the damages caused by the tsunami in the walls of the water inlet by planting steel tubes in the water. This requires opening the fence, and allowing some radioactive materials from the inlet to flow into the harbor. 14 m³/h of nitrogen will be injected into unit 3 starting 12 July. The robot found 50 mSv/h near the heat exchanger on the second floor of unit 2, which hampers the work that has to be done there. 6 people among the 9 initially feared have been confirmed to have exceeded 250 mSv.

 

[etudiant]

On June 1 the remain decay heat output in unit 1 was 3.7 MW while in units 2 and 3 it was 6.3 MW, which is 0.26% of thermal output at shutdown. Over the next 8 months that will go down to 0.21% of thermal output at shutdown, so it's essentially steady now (http://mitnse.com/2011/03/16/what-is-decay-heat/" ), since most of the iodine-131 and other shortlived isotopes are largely gone.

Water injection in units 1 and 2 is currently running at 3.5 t/h, while unit 3 is receiving 9 t/h, even though unit 2 and 3 should have the same decay heat output. If all the heat was being dissipated by boiling they would consume the same amount of water. Unit 3 is receiving more water because measured temperatures at the lower end of the RPV were higher.

If temperatures in unit 2 are lower despite only receiving 1/3 of the amount of water, perhaps most of the fuel there has already left the RPV and has splashed onto the containment concrete floor. Alternatively, the shape of the corium may obstruct water flow in the RPV of unit 3, so water boils on top of it but doesn't flow past it.

Units 2 and 3 should be largely identical, except that unit 3 was more recently refueled and therefore the average burn-up rate of its fuel should be lower, hence there should be marginally *less* decay heat output in unit 3 than unit 2.



Unit 1 had 68 t fuel enriched to 3.4% while unit 2 and 3 had 94 t enriched to 3.6%.

It is interesting that the temperatures are being stabilized with these low levels of water injection. The decay energy created must go somewhere, so if it is not taken up by the injected water, it must be heating up the water in the plant. Given that there are about 100,000 tons of water in the plant and that we are apparently dissipating about two thirds of the energy ( about 10 megawatts) into the existing pool. The specific heat of water is about 4 joules/gram, so the conversion would be roughly:
10x10**6j/sec / 4 j/gm =2.5 x10**6 gm/s heated 1 degree. There are 10**11 grams (10**5x10**6) of water in the plant, so the hourly heating of the plant pool should be 10**11 gm / 9x10**9 gm/hr (3.6x10**3s/hr x2.5x10**6gm/sec), which rounds out to one degree every 10 hours.
This is clearly too high, as the plant would be swimming in boiling water after a few weeks, which it is not. So where has the energy gone?

 

[robinson]

I'm just going by what I see happening in the rare video. #3 seems to have a boiling fuel pond.

 

[hellbet]

So where has the energy gone?

Tepco only cares of the "inside" part of the melted fuel that is the main part of so-called "corium" has probably escaped out the containment. How would you possibly care of something that is out of range? Frankly, I'm afraid we're now facing at some possible "melt-out" event taking place after all sort of barely admitted "melt-something".

 

[joewein]

I'm just going by what I see happening in the rare video. #3 seems to have a boiling fuel pond.

No it doesn't. That video is not exactly new.

According to status updates, an "alternative cooling system" for the spent fuel pool of unit 3 has been in place since July 1:

<Cooling by the alternative cooling system for the Spent Fuel Pool>
July 1 11:00 ～ July 8 08:20, July 8 14:24 ～
(Source: http://www.nisa.meti.go.jp/english/press/2011/07/en20110711-1-2.pdf" )

Furthermore they are working on one for unit 4 too:

The alternative cooling system for the Spent Fuel Pool of Unit 3 was
temporarily suspended due to the installation works of the alternative
cooling system for the Spent Fuel Pool of Unit 4. (from 08:20 till 14:24 July 8)
(Source: http://www.nisa.meti.go.jp/english/press/2011/07/en20110710-1-1.pdf"

 

[joewein]

Tepco only cares of the "inside" part of the melted fuel that is the main part of so-called "corium" has probably escaped out the containment.

What makes you think the melted fuel has left the containment? Where do you think it is now located and why do you think so?

Of course a lot of the more volatile substances in the core have left the containment, as one can see from the radiation levels in the basement of the reactor building and turbine hall, but the less soluble substances are likely to be either inside the RPV or on the containment floor.

If all of it had left the RPV, the RPV bottom temperatures would not respond to the water flow because there would be no heat source to interact with the water flow, even more so if all of it had not only left the RPV but also the containment.

 

[tsutsuji]

No it doesn't. That video is not exactly new.

According to status updates, an "alternative cooling system" for the spent fuel pool of unit 3 has been in place since July 1:Furthermore they are working on one for unit 4 too:

Concerning unit 4 they said that they could restore a vital pipe called "FPC-68" for that purpose : http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110709_02-e.pdf. Details explaining why they had to stop unit 3 SFP cooling equipment to allow starting the construction of the cover structure at unit 4 are provided in http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110708_01-e.pdf .

The spent fuel does need cooling as well, but normally a cooling circuit keeps the refrigeration going.
Afaik, that has been restored at the SFPs for reactors 1-3, but is still not there for reactor 4, because the explosion blew out part of the cooling pipes.

As Joewein says above, the cooling has been restored for the SFP at unit 3. What is making you think it has been restored for unit 1 as well ?

On http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/11071106_table_summary-e.pdf the SFP temperature at unit 1 is still marked today with "instrument failure" which makes me doubt much equipment has been restored there.

Concerning unit 2, the SFP circulating cooling system has been running since 31 May, according to http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110711_05-e.pdf page 3. It is also marked as "May 31 17:21 Started full-fledged operation of the alternative cooling system for the Spent Fuel Pool" on http://www.nisa.meti.go.jp/english/press/2011/07/en20110711-1-2.pdf page 5.

 

[etudiant]

Concerning unit 4 they said that they could restore a vital pipe called "FPC-68" for that purpose : http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110709_02-e.pdf. Details explaining why they had to stop unit 3 SFP cooling equipment to allow starting the construction of the cover structure at unit 4 are provided in http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110708_01-e.pdf .



As Joewein says above, the cooling has been restored for the SFP at unit 3. What is making you think it has been restored for unit 1 and unit 2 as well ?

On http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/11071106_table_summary-e.pdf the SFP temperature at unit 1 is still marked today with "instrument failure" which makes me doubt much equipment has been restored there. The news I summarized above about unit 2 says that the radiation hampers the work, so I also doubt a lot of work has been performed at unit 2. See also http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110711_04-e.pdf concerning the radiation measurements in unit 2 reactor building.

The JAIF status report summary here:

http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1310358115P.pdf

states that the SFP cooling function for reactors 2 and 3 have been restored and that SFP for reactor 1 is now receiving water from the SFP coolant clean up line ( not sure what that represents).
I was mistaken to believe that the reactor 1 SFP was already getting circulation cooling.

 

[tsutsuji]

The JAIF status report summary here:

http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1310358115P.pdf

states that the SFP cooling function for reactors 2 and 3 have been restored and that SFP for reactor 1 is now receiving water from the SFP coolant clean up line ( not sure what that represents).
I was mistaken to believe that the reactor 1 SFP was already getting circulation cooling.

And I was mistaken concerning unit 2. I edited my previous post concerning that unit.

If I try to gather information concerning unit 1 SFP :

NISA press conference 2011.06.24 11:10 http://www.ustream.tv/recorded/15577343 : it is expected that the original primary circuit at the unit 1 SFP cooling system can be reused instead of creating a new one as was previously thought.

http://www.nisa.meti.go.jp/english/press/2011/07/en20110711-1-2.pdf page 3 : "<Fresh water injection to SFP via FPC (using the temporary motor-driven pump) > May 29 11:10～15:35, June 5 10:16～10:48, July 5 15:10～17:30" (compare with unit 2 SFP on page 6, saying the last water injection was performed on May 30)

http://www.meti.go.jp/press/2011/07/20110711006/20110711006-1.pdf page 8 : the amount injected into SFP on July 5 was about 75 tons.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110711_05-e.pdf page 3 : "status of cooling" marked with "no plan on 7/11". ( http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1310358115P.pdf translates　http://www.jaif.or.jp/ja/news/2011/110711status_of_countermeasures-j-188.pdf's 検討中 as "planned", but a more accurate translation would be "under study" ; conversely, unit 4's 作業中 should translate as "under work" rather than "Construction to be prepared").

from the SFP coolant clean up line ( not sure what that represents).

They mean that they no longer pour water using a concrete pump truck, using instead the original pipes of the Fuel Pool Cooling and Purification System, sometimes shortened as "FPC". Apparently the pump (according to http://www.ustream.tv/recorded/15577343 ) and the pipes in the primary system are OK, but the secondary system (the pipes and pump(s) bringing sea water for cooling) has collapsed. I am not sure about the status of the heat exchanger.

By the way, concerning unit 4, there is a big translation mistake. 20A/B弁閉操作完了　on http://www.tepco.co.jp/nu/fukushima-np/images/handouts_110709_02-j.pdf means "finished the closure operation of valve 20A/B", not "opened 20 A/B valve" as translated in http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110709_02-e.pdf