Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[Reno Deano]

From NEI: http://nei.cachefly.net/newsandevents/information-on-the-japanese-earthquake-and-reactors-in-that-region/health-and-radiation-safety/"

Excerpt:

What the Experts Are Saying

"The fear is out of proportion to the actual risk right now. With regard to health effects, probably the largest effect will be psychological." (CNN)
-John Boice, Vanderbilt University epidemiologist

"Fear dominates our intention. The earthquake and tsunami are over, but with nuclear energy, who knows? We are used to thinking of industrial accidents, but with nuclear we are talking about what could happen. I cut my teeth on Three Mile Island, because there was a sense that we almost lost the Eastern part of the U.S. The biggest health problem from Three Mile Island was fear, the anxiety and mental stress that people had." (NPR)
-Dr. Robert DuPont, Georgetown University professor of psychology

"The fact that they can detect something doesn't mean it's harmful. It's important to understand that difference." (USA Today)
-Richard Morin, American College of Radiology safety committee chair

"This is indeed a really serious event, but it has to be put in the context of the earthquake and tsunami which led to it - and which has been the direct cause of massive suffering, which is still continuing. Obviously there are threats from the nuclear power station, but they are limited and they are quantifiable. It's not a Chernobyl. ... One of the biggest risks from radiation is the psychological damage it causes. After events like the 1979 partial meltdown at Three Mile Island, Pennsylvania, and the Chernobyl accident, there was substantial psychological trauma, even among people who were not affected, because there is such a fear of radiation and its long-term consequences." (New Scientist)
-David Spiegelhalter, Winton Professor of the Public Understanding of Risk at the University of Cambridge

 

[TCups]

@TCUPS: did you have a look at my post just above yours and at my other post with the big captures of the drawings on the NHK TV at page 72 of the thread?

Because i think they answer some of your questions concerning the basement, the location of the workers and water, the location of the basement relative to sea level,and confirms also your remark concerning the shift of the reactor towards the East side of the building, and the corresponding smoke position...)

Sorry, jlduh - my long post apparently pre-occupied me while you were posting. I have read your post now. It seems your image links will only come up as very small thumbnail images. These are not sufficient to make your point.

I will check page 72 . . .

 

[83729780]

Has there been any conformation of the exact location of "the basement in building 3" that was so contaminated? Does this mean the basement of the Reactor Bldg 3 in the region of the torus? Does this mean the basement of the Steam Turbine Bldg 3? Is there a basement in the region of the control room? I have not heard where the infamous basement is located.

It was in the basement of the turbine building (the one with the huge hole on the roof).

this from the NY Times:

But Michael Friedlander, a former nuclear power plant operator for 13 years in the United States, said that the presence of radioactive cobalt and molybdenum in water samples taken from the basement of the turbine building of reactor No. 3 raised the possibility of a very different leak.

Both materials typically occur not because of fission but because of routine corrosion in a reactor and its associated piping over the course of many years of use, he said.

These materials are continuously removed from the reactor’s water system as it circulates through a piece of equipment called a condensate polisher, which is located outside the reactor vessel. The discovery of both materials in the basement suggests damage to that equipment or its associated piping, as opposed to a breach of the reactor vessel itself, Mr. Friedlander said.

The condensate polisher is also located in the basement of the turbine building, where the tainted water was found. By contrast, the reactor vessel is actually located in a completely different, adjacent building, and would be far less likely to leak into the basement of the turbine building.

http://www.nytimes.com/2011/03/26/world/asia/26japan.html?pagewanted=2&hp

I'd like someone to comment on the possibility that the very heavy (and hot) debris that smashed through the turbine building also ruptured the pipes through which the coolant water is circulating.

 

[Joe Neubarth]

Good point -- yes, there was that source of water, also. ()

I had heard that the Turbine building was not flooded earlier. So the question is where did the water come from all over again. That reactor Three explosion was a hellofa release of energy. Cracked foundation with seepage is a possibility. Some of that seepage could have been highly radioactive.

 

[Joe Neubarth]

Sorry to step back regarding the neutrons. I heard that the water has the effect to slow down the speed of the neutrons.

If this is correct, in the Spent Fuell pool, the neutrons with high speed will go through the fuell without making contact with the fuell and thus reduce the nuclear reaction.

If they add water, it will reduce the speed of the neutrons that will making more contact with the fuell and then increase the nuclear reaction.

The fact to put water in the pools will accordingly have the effect of making more nuclear reaction, isn't it correct ?

Water does slow down the neutrons so that they cause more fissions with Uranium. An outsider like me can only assume that they have some neutron suppression like boron in the water normally.

 

[TCups]

Water does slow down the neutrons so that they cause more fissions with Uranium. An outsider like me can only assume that they have some neutron suppression like boron in the water normally.

I don't think there is any way that spraying water or even immersion in water (as in the SFP) would risk "criticality" and a spike in radiation from a nuclear chain reaction. On the other hand, the danger of not spraying water and cooling the rods would be damage to the rods and more release of radionuclides from the damage rods. The former is a non-problem, the later is very real and potentially very dangerous. The added potential danger from spraying water might be spreading radionuclide contamination from the run off.

 

[TCups]

I had heard that the Turbine building was not flooded earlier. So the question is where did the water come from all over again. That reactor Three explosion was a hellofa release of energy. Cracked foundation with seepage is a possibility. Some of that seepage could have been highly radioactive.

see 83729780's post #1167. The contaminated water contained radioactive Co and other trace radionuclides implicating a "polisher" unit and suggesting leakage from internal plumbing coming from the reactor, into the Turbine building caused the flooding in the basement of Turbine Bldg 3, I believe.

Still, this might only imply significant damage to "plumbing" coming from the reactor vessel rather than to the reactor vessel itself, though I am not sure that is much of a comfort.

The point, if I understand it, is that if the damage were to the "plumbing", and if this were the source of the contaminated waters in the basement, and that if it occurred within the Turbine Bldg 3 rather than the reactor, then the mechanism of damage might be very different from damage within or around the RV and primary containment of Bldg 3.

 

[artax]

I still find it hard to believe they've not sent a Radio Controlled helicopter/camera in!
They could get right in there, crikey it's been two weeks now!
I could get better images with a 200 dollar chopper/my casio EXILIM and a bit of gaffer tape!

 

[KateB]

I don't think there is any way that spraying water or even immersion in water (as in the SFP) would risk "criticality" and a spike in radiation from a nuclear chain reaction. On the other hand, the danger of not spraying water and cooling the rods would be damage to the rods and more release of radionuclides from the damage rods. The former is a non-problem, the later is very real and potentially very dangerous. The added potential danger from spraying water might be spreading radionuclide contamination from the run off.

From what I understand, after the Spent rods are exposed and begin heating again, the addition of water could, in theory, instigate a recriticality. But it is a catch-22, because if you don't introduce water, then you could have an uncontrolled criticality/heating, that unchecked could become another source of worry, i.e. corium. It worried me that the water that was dumped from the Chinook obviously was sans Boron, as with it, the water is less a modulator and more a coolant. Correct me if I am wrong. Thanks for the great information, everyone.

 

[TCups]

http://www.nytimes.com/2011/03/26/world/asia/26japan.html?_r=1&hp" suggests that radioactive water comes from the condensate polisher:

In the extended quote of M. Friedlander, (post above):

"He said the company had found the same problem with contaminated water in the basements of the No.1 and No. 2 turbine buildings as that which caused the men’s injuries in the No. 3 unit. Removing the radioactive water will delay the work of restarting cooling systems."

This, of course, would mean that the holes in the roof of Turbine Bldg. 3 are NOT related to any of this, and that salt water and the resulting build of of NaCl and perhaps CaCO₃ may be significant in explaining what has occurred, as I believe, others have posted.

This would seem to imply

1) that sea water was used as a coolant inside the RV's, which I believe is the case,
2) that at least to some extent, given the basement contamination in the Turbine Bldgs of 3 separate units, that loss of integrity of the contents of the reactor vessels has occurred in Units 1, 2, and 3

Am I following correctly?

Addendum:
Might it also imply that the most direct route to restoring circulating fresh water cooling, perhaps the only route to restoring fresh water cooling, is by access to the now highly contaminated basements in the turbine buildings?

 

[AntonL]

Today is day 14 since the accident.

Google "Nuclear experts specialist fly to Japan" and nothing of relevance is returned.
Why has a international nuclear expert community not arrived in Japan, helping TEPCO
to analyze the data and brainstorm best actions.

I personally feel that Tepco engineers are overextended, paralyzed and firefighting,
instead of having a set clear path of action with small deviations to solve the problem.
The question now arises if nuclear reactor accidents should be co-managed internationally,
an new task for the United Nations as they are the only body to enforce this.

This accident will pose many questions. Such as why was the sea water injection allowed to
continue so long? To keep the reactors at constant temperature by latent heat of
evaporating water, would have by now consumed 7100m3 this is on average two 10T tanker
trucks every hour over the period - that is manageable. Now about 210 tonnes of salt is
distributed in 3 reactors.

This picture tells everything: Overwhelmed Tokyo Electric Power Company Managing Director
Akio Komiri cries as he leaves after a press conference in Fukushima (18/3/2011),
(and Japanese usually do not show emotion publically)

 

[tortamuss]

The Leidenfrost effect keeps popping into my mind. Any thoughts?

 

[AntonL]

I still find it hard to believe they've not sent a Radio Controlled helicopter/camera in!
They could get right in there, crikey it's been two weeks now!
I could get better images with a 200 dollar chopper/my casio EXILIM and a bit of gaffer tape!

It is not in public interest to show high resolution pictures, I am sure these they have, that
what they are releasing is to show that they are working hard. The general public is not
educated and believes what is fed to them, if they told it is OK then it is OK. The PR machinery
is hard at work to keep a sense of calm.

 

[AntonL]

Addendum:
Might it also imply that the most direct route to restoring circulating fresh
water cooling, perhaps the only route to restoring fresh water cooling, is
by access to the now highly contaminated basements in the turbine buildings?

Cooling by latent heat of evaporating water is not a long term solution as
the steam has to go somewhere. If the reactors where running 80% capacity
at the time of the accident then the heat generated by the decay of the
fission products would be 3.9MW for unit 1 and 3.9MW for units 2 and 3 today
and reducing to 0.7 and 1.2MW in half a years time. External cooling by circulation
and heat exchanger is the only solution, and with all that salt circulation of
fresh water is not possible, the salt is there to stay.

http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf" an explain how the salt should be removed

 

[TCups]

ADDITIONAL INFORMATION ABOUT CONTAMINATED BASEMENT FLOODING

Source: http://www.world-nuclear-news.org/RS_Fukushima_Daiichi_two_weeks_on_2503111.html

QUOTING, IN PART:

"Investigations are now underway into the unexpectedly high level of contamination in the water, particularly as the basement of the turbine building is not a recognised radiation area. One theory is that there is a leak from the reactor circuit, but pressures in the reactor vessel indicate this must be elsewhere in the loop."

Added emphasis is my own. Elsewhere in the loop, indeed.

 

[KateB]

Cooling by latent heat of evaporating water is not a long term solution as
the steam has to go somewhere. If the reactors where running 80% capacity
at the time of the accident then the heat generated by the decay of the
fission products would be 3.9MW for unit 1 and 3.9MW for units 2 and 3 today
and reducing to 0.7 and 1.2MW in half a years time. External cooling by circulation
and heat exchanger is the only solution, and with all that salt ...

Post #1084 talks of the Marines having flat hoses/pumps that can collect freshwater from nearby lakes, would it also be plausible to use said pumps to get the water cycled in, out? In order to restore function to the cooling system(if repairable at all)? IF they could get enough pumps and hoses, could they conceivably pump water from the lakes in and pump the cycled water out, as a short term solution(or long term depending on the repairability of the cooling system) though awful in the long term, thinking of all that material hitting the sea...But the alternative is...
Also, would there be a way to cycle in boron through the hoses?

 

[AntonL]

ADDITIONAL INFORMATION ABOUT CONTAMINATED BASEMENT FLOODING

Source: http://www.world-nuclear-news.org/RS_Fukushima_Daiichi_two_weeks_on_2503111.html

QUOTING, IN PART:

"Investigations are now underway into the unexpectedly high level of contamination in the water, particularly as the basement of the turbine building is not a recognised radiation area. One theory is that there is a leak from the reactor circuit, but pressures in the reactor vessel indicate this must be elsewhere in the loop."

Added emphasis is my own. Elsewhere in the loop, indeed.

Basically if things go wrong in BWR NPP the complete site becomes a radiation site. you have pipes leading from the reactor carrying steam and returning water into the turbine building, scrubbers and heat exchangers. In a partially molten core and sea water coolant any breach of a pipe in the turbine building is a breach of the the reactor vessel to the outside. This is a big flaw in BWR design and after this accident all BWR in operation should be shut down.. Pressurized Water reactors have addressed this problem.

 

[|Fred]

Reactor 1's turbine building basement just got flooded with highly radioactive water just like n°3 did yesterday..
reported at 00:30 (Japan Standard Time) on the 26th of April

 

[AntonL]

Post #1084 talks of the Marines having flat hoses/pumps that can collect freshwater from nearby lakes, would it also be plausible to use said pumps to get the water cycled in, out? In order to restore function to the cooling system(if repairable at all)? IF they could get enough pumps and hoses, could they conceivably pump water from the lakes in and pump the cycled water out, as a short term solution(or long term depending on the repairability of the cooling system) though awful in the long term, thinking of all that material hitting the sea...But the alternative is...
Also, would there be a way to cycle in boron through the hoses?

Rethink your post http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf" all the water that has been pumped into the reactors for the last 14 days has been boilded away, partly released to atmospher intentionally, partly unintenyionally and some condensed in the dry well and torus.

 

[Joe Neubarth]

Today is day 14 since the accident.

Google "Nuclear experts specialist fly to Japan" and nothing of relevance is returned.
Why has a international nuclear expert community not arrived in Japan, helping TEPCO
to analyze the data and brainstorm best actions.

I personally feel that Tepco engineers are overextended, paralyzed and firefighting,
instead of having a set clear path of action with small deviations to solve the problem.
The question now arises if nuclear reactor accidents should be co-managed internationally,
an new task for the United Nations as they are the only body to enforce this.

This accident will pose many questions. Such as why was the sea water injection allowed to
continue so long? To keep the reactors at constant temperature by latent heat of
evaporating water, would have by now consumed 7100m3 this is on average two 10T tanker
trucks every hour over the period - that is manageable. Now about 210 tonnes of salt is
distributed in 3 reactors.

This picture tells everything: Overwhelmed Tokyo Electric Power Company Managing Director
Akio Komiri cries as he leaves after a press conference in Fukushima (18/3/2011),
(and Japanese usually do not show emotion publically)

American nuclear experts were there on day three of the crisis. The news reports said that they were receiving regular briefings. That to me says they were being informed as to what the Japanese wanted them to know, BUT that their expertise was not being solicited or appreciated at that time. A couple of days later there was a news release showing that the Americans were working with the Japanese. What Japanese we do not know. Hopefully their contribution was not going for naught.

 

[Joe Neubarth]

Rethink your post http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf" all the water that has been pumped into the reactors for the last 14 days has been boilded away, partly released to atmospher intentionally, partly unintenyionally and some condensed in the dry well and torus.

If the primary coolant loop is not leaking the only radioactive alternative is the condensation of radioactive steam. I think they have a primary leak and are not telling us all of the truth.

 

[TCups]

Breaking news: Reactor 1's turbine building basement just got flooded with highly radioactive water just like n°3 did yesterday..
reported at 00:30 (Japan Standard Time) on the 26th of April

Fred:

You left out Unit 2. See post #1176 and shadowncs's post a few earlier than that. I am glad to see I am not the only one having trouble keeping up

OOPS! Sorry Fred, post #1175 is the correct reference ()

 

[AntonL]

Breaking news: Reactor 1's turbine building basement just got flooded with highly radioactive water just like n°3 did yesterday..
reported at 00:30 (Japan Standard Time) on the 26th of April

Kyodo news article

http://english.kyodonews.jp/news/2011/03/81133.html"

does not make good reading

 

[Astronuc]

From what I understand, after the Spent rods are exposed and begin heating again, the addition of water could, in theory, instigate a recriticality. But it is a catch-22, because if you don't introduce water, then you could have an uncontrolled criticality/heating, that unchecked could become another source of worry, i.e. corium. It worried me that the water that was dumped from the Chinook obviously was sans Boron, as with it, the water is less a modulator and more a coolant. Correct me if I am wrong. Thanks for the great information, everyone.

Spent fuel generates heat from the decay of fission products. Some radionuclides decay in seconds, minutes, hours, days, . . . , but as time goes on the shorter half-life nuclides decay away rapidly leaving the longer half-life nuclides which decay more slowly. The decay process is ongoing, unlike the fission process, which can be 'shutoff' by making a system subcritical.

Water is a good conductor of heat, unlike steam or air which has low heat capacity (and low density) as well as low thermal conductivity.

Criticality is unlikely in the core assuming the control rods remain intact. The fuel could be damaged, but as long as the control rods remain inserted between the fuel assemblies, the core remains subcritical. Also, without water, the core would remain subcritical, since there is no moderation. Similarly, the SFPs should remain subcritical, by design, as long as the neutron absorbing material in the walls of the racks remains intact.

Dumping water from the air was pretty much ineffective. I think most of the water did not get to the SFPs, but rather sprayed onto the structures or otherwise outside of containment. It seems to me that the pilots did not understand the significance of what they were trying to accomplish. It's not like dropping water on a forest fire. The target of the water drop was very specific and very localized.

For a BWR SFP, boron in the water should not be necessary to achieve criticality. Unlike a PWR, BWRs do not use boron in the coolant because boiling normally occurs in the core, and the deposition of boron compounds on the fuel would be problematic from a reactivity control (power distribution) aspect.


Meanwhile - http://news.yahoo.com/s/ap/20110325/ap_on_bi_ge/as_japan_earthquake

The contaminated water outside of containment could be coming through the recirculation or feedwater system. The system normally collects water from the condenser, which comes after the turbine, or the reheaters which bleed off condensed steam (water) from the turbines, and pumps the water back to the reactor vessel.

The fuel does not have to melt for there to be fuel released from the cladding. An open crack can allow fuel particles to be collected in the coolant, which can there makes its way to any connected pipe, possibly into the feedwater system, which includes condensate polishers (filters).

The corrosion products, including Co, would indicate that water from the primary system is leaking outside of containment, possibly through the feedwater system or other ancillary systems.

 

[Borek]

Google "Nuclear experts specialist fly to Japan" and nothing of relevance is returned.

Try "Nuclear experts sent to Japan" then.

 

[TCups]

If the primary coolant loop is not leaking the only radioactive alternative is the condensation of radioactive steam. I think they have a primary leak and are not telling us all of the truth.

"They"? Most of us think "they" have a breech in containment. High level waste in the basements of Turbine Buildings doesn't happen normally. Do you mean, by "primary leak", a leak in the reactor vessel (RV) or a leak in the Primary (Drywall) containment, or both?

I think the information is fragmented, and understandably so, given the situation on the ground. This isn't TMI where there was only one reactor at risk, where reporters were camped out 24/7, where the surrounding infrastructure wasn't devastated, and where there wasn't a surrounding catastrophe of Biblical proportions surrounding the event, and completely independent of any reactor accident(s).

source: https://www.physicsforums.com/private.php?do=showpm&pmid=312554

A situation summary from the World Health Organisation put the death toll from the 11 March earthquake and tsunami at over 8800 confirmed dead with more than 12,600 still missing. More recent reports now put the cost at over 10,000 lives.

In total almost 320,000 people have been evacuated, with over 130,000 of these from Fukushima prefecture for reasons of both the tsunami and the nuclear emergency.

Over 220,000 homes are still without access to electricity, notwithstanding the non-operation of nuclear and fossil power plants. Gas supplies are disrupted to almost 440,000 homes. Some 1700 roads are damaged with many of these closed. More than 50 bridges are down.

There is a lot going on that "they" might not have told us yet, it is true. Concentrate on what we do know and let's not ascribe some malicious intent to any lack of information we on the net haven't been made privy to just yet.

 

[AntonL]

For a BWR SFP, boron in the water should not be necessary to achieve criticality. Unlike a PWR, BWRs do not use boron in the coolant because boiling normally occurs in the core, and the deposition of boron compounds on the fuel would be problematic from a reactivity control (power distribution) aspect.

For emergency Boron is injected into the BWR reactor, http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf"

 

[Astronuc]

For emergency Boron is injected into the BWR reactor, http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf"

Yes - only in an emergency! If the reactor was returned to operation, the entire primary system would have to be flushed.

Boron is not normally introduced into the primary coolant system, for the reason I stated above. Injecting borated coolant is extraordinary, and indicates a serious matter.

Injecting seawater and boron into the core, especially for days or weeks, pretty much means those units will never operate again - unless essentially the entire primary system is replaced.

 

[Gilles]

Gentlemen, I read that on a French forum

Regardez la video au dessus du reacteur N° 3 . A 0:30 secondes faites un arret sur image et vous verrez une lueur orange/rouge dans le tas de beton.
C'est le coeur du reacteur qui est à l'air libre et en fusion (Temp: à partir de 3000° et ça ne va pas refroidir avant des mois ou des années...)
Ces matieres en fusion (Corium) ont sans doute deja percé l'enceinte d'acier puisqu'on les voit et sont en train de percer la dalle beton de 6 ou 8 metres d'épaisseur.
Si jamais cette masse en fusion rencontre de l'eau = explosion (Craking de l'eau) et liberation de tres grosses quantités de matieres...
Donc on en est au meme stade tres grave qu'a Tchernobyl. Sauf que les charges radioactives de ces reacteurs là sont beaucoup plus
dangereuses et puissantes avec en plus du plutonium...et il y a 3 reacteurs HS au lieu d'1.
Bref, c'est pas fini cette histoire et je suis pessimiste pour l'avenir dans ce pays qui est minuscule...et tres peuplé. Pauvres gens et peut etre pauvres de nous...
J'espere me tromper mais cette lueur orange est edifiante...d'autant plus que les fumées viennent de là...

and now the translation (sorry for the possible broken English)

look at the video above the Reactor Nb 3. At 30 sec make a pause and you'll see an orange glow among the concrete heap.
It's the glowing core of the reactor, in free air and in fusion. (Temp> 3000 °C and it won't cool before months and years). This molten material (corium) has already come through the steel vessel since we can see it and is being piercing the 6-8 meters thick concrete slab. If this molten mass meets water - explosion (water cracking) and emission of large amounts of [radioactive] material.

So we're at the same very ominous stage as in Tchernobyl - except the RA loads are much more dangerous and powerful, with a lot of Pu , and with 3 reactors out of order instead of 1.
So this story is far from being over, and I am very pessimistic about the future of this tiny and overpopulated country. Poor people, and maybe poor us ...

I hope being wrong but this orange glow is telling .. and the smoke is coming from there..

and the screen shot

[PLAIN]http://www-laog.obs.ujf-grenoble.fr/~henri/Fukushima.gif

what's your opinion?

 

[AntonL]

Try "Nuclear experts sent to Japan" then.

I did and found this - US deploys two nuclear experts to Japan - You need a team, each assigned to subtasks, reactors, cooling, SFP, data collection etc etc

All I want to say is that nuclear accident management need to be rethought and taken out of the control of the operator. It would be of interest if the big nuclear nation have a national emergency manual that structures the accident management that takes immediate effect with military like precision.

 

[83729780]

for perspective: some good news:

Japanese authorities have informed the IAEA that on March 24, examinations of the thyroid glands in 66 children (14 of which are infants) were conducted near the evacuation area around the Fukushima nuclear plant. The exams were conducted at the Kawamata Town Health Center (40-50 kilometres from Fukushima Daiichi NPP) and Kawamata Town Yamakiya Branch Office (30-40 kilometres from Fukushima Daiichi NPP).

According to a 25 March 2011 Nuclear and Industrial Safety Agency press release, the results of the examinations indicated that the dose rate "of all the 66 children including 14 infants from 1 to 6 years old had no big difference from the level of background and was at the level of no problem in light of the view of Nuclear Safety Commission."

http://www.iaea.org/newscenter/news/tsunamiupdate01.html

Kawamata is about 40 km NW of the Daiichi plant.

These exams are done peripherally right? No direct examination of tissue?

 

[AntonL]

what's your opinion?

repeating what has been discussed her a week ago. old video

 

[Borek]

what's your opinion?

I see many other orange spots in the video.

 

[AntonL]

Yes - only in an emergency! If the reactor was returned to operation, the entire primary system would have to be flushed.

Boron is not normally introduced into the primary coolant system, for the reason I stated above. Injecting borated coolant is extraordinary, and indicates a serious matter.

Sorry - I misread you original mail

 

[Borek]

I did and found this - US deploys two nuclear experts to Japan - You need a team, each assigned to subtasks, reactors, cooling, SFP, data collection etc etc

Plus Russian, Korean, Ukrainian, EU and UN experts, check following pages.

But it is obvious that while these experts can try to help, locals have the best knowledge about the system and situation.