Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[Jorge Stolfi]

X-ray film?

You cannot focus neutrons and gamma rays to make an image on film. (X-ray imaging works because the source is point-like; there are no lenses involved in image formation.)

 

[Dmytry]

Jorge Stolfi: well perhaps you can make pinhole cam... but i don't think it'd work well. For cosmic rays, you can have several detectors and do tracks. I don't know if that would work for gamma. I think not. It'd scatter too much in the first detector.

edit: wow, see this: http://science.nasa.gov/science-news/science-at-nasa/balloon/mixe2/
but again I don't know what would be the range of that thing in air. But I think it can work.

Hm... I don't think that's the problem here. I'd rather ask "How did it get there?"

NHK World wrote "has been found near the reactor". So it's outside the reactor. And considering its classification as "concrete fragment", it has most likely been ejected from either Unit 3 or Unit 4.
But if there really is Corium embedded in this piece, then I have absolutely no idea how it was able to leave the reactors. Corium is flowing down, not up. But the explosions happened on top of the RPVs. Far above of the reactor fuel rods. Maybe there has been Corium. But it should be impossible for it to get ejected.

I know that TCups has a theory about the explosion at Unit 3. It's thousands of posts away, but if I remember correctly, he assumes that the Unit 3 explosion breached the SFP, boiled the water away and ejected the fuel handling machine - probably with fuel rods.
So perhaps a little chunk of fuel elements landed on a rubble part, got hot and fused with it, forming the dangerous concrete block?

What would happen, if a fuel rod would be ejected from the SFP and totally broken apart by the force of the explosion, so that all uranium pellets impact individually on site? Would they heat up and melt through the surface?

No, individual pellet won't melt through surface. A pile might.
Reactor core is something on order of hundred tons of uranium (ton = 1E6 grams), maybe more. Individual pellet is 10..20 grams at most by the look of it. Let's say core makes few tens megawatts of decay heat, then the individual pellet makes few watts at most, and that's shortly after shutdown.
You could read what it was like in Chernobyl if you want to know what fuel does after being blown apart.

An NRC paper stated that there was highly radioactive rubble which was bulldozed over - possible fuel pellets?

Dunno, I'd guess so, no idea what else it could've been, they don't tell how radioactive that 'highly radioactive' rubble was.

 

[tsutsuji]

To all: please stop discussing politics, management and other things unrelated to the technical aspects of the Fukushima situation. Fell free to discuss these things in separate threads, but not here.

I am leaving this forum as a protest against the censorship exerted against my last post. My last post was deleted without any prior warning or posterior explanation whatsoever. This is rude.

Someone asked me a question in reference to my last post. I was gathering information to provide an anwer to that question when I found that both my last post and the question in reference to my last post had been deleted. There is a probablility that the answer to that question, concerning the relevance of the INTRA robots, is technical.

My conviction is that decision making and technical matters are intimely intricated when a crisis like the Fukushima crisis is concerned. Dealing with the latter while ignoring the former can only provide a biased vision of the situation. Therefore I would rather leave than collaborate to a biased form of reporting.

Trying to create a "pure science" detached from men and women's lives is anti-humanist.

A 16th century writer said :

science without conscience is but the ruin of the soul

http://en.wikiquote.org/wiki/François_Rabelais

 

[com.oligarchy]

Wasn't there a set of photos showing heat more
concentrated in the center of reactor building 4?
Indicating the reactor was hot. Funny how this is
the explosion we don' have video of.

Guess the Toshiba re-shroud, doesn't work and we
will have to retire these reactors like the original
design said, after 30 years. I remember way back then
they said the concrete absorbs radiation over time and
cant be refitted, site reused. They also said they were
going to dry cask, and create a central storage location
in the shield, or something. Reptilian and sociopathic

right, sorry, no politics, just the facts now

 

[michael200]

Just because high dose material has been found on the site is not surprising. The destroyed building next to the unit 3 reactor building is the radwaste building. Also I would not be suprised if the u3 and u4 fuel pool demineralizers were damaged in the explosions. Radioactive does not mean fuel is flung around the site. It doesn't take a lot of co60 to provide a 1 sievert source.

 

[NUCENG]

NUCENG, I truly appreciate your posts and those of others who have posted here with specific industry knowledge and/or perspective. It helps keep the discussion on track and informative. That said let me respond in a general way to you as a representative of your profession. Nothing personal intended or implied.

The death toll from the quake and tsunami is around 30,000 people. The exact figure is still climbing as it has been hard to determine the number of missing given the scale of destruction. Who knows how many will die when LA or San Fransisco or Lisbon or Tokyo (etc.) is shaken by another 'big one'. Human nature and behavior intersecting with natural forces that manifest sporadically, unpredictably (regarding the precise time of an event, not necessarily it's probability) and with great force - many types of examples come to mind here. However, this is quite a different matter from the accident at Fukushima.

The attitude of the staff and management at TEPCO was that such an accident was impossible and no preparations had been made or consideration given to the possibility. Training and equipment to deal with a serious accident was not implemented or acquired, one of the rationals being that to pursue such matters would show insecurity or fear and call into question the safety of nuclear plants.

The historical and scientific knowledge about tsunamis was not properly considered given the known risks to plants on the coast. It was stated that unit 1 was constructed with an 'off the shelf' plan from GE that wasn't modified to suit the site specific risks because the engineers were not familiar enough with plant design to confidently recommend changes to it. Once the first unit was built the following units were added using the same basic format, incorporating the same site-based flaws. This was not corrected later because of cost, and as above, because the major changes required would have been acknowledgment that the original design wasn't safe.

When the accident occurred (first couple of days) the site technicians were left on their own to do the best they could while upper management was MIA. There was a fundamental misunderstanding of the seriousness of the situation (one shared by many in the nuclear power industry around the world) that resulted in hesitation to take necessary steps. TEPCO balked at venting, because of liability issues most likely, as well as the use of seawater for cooling because of concerns for their investment.

When it became clear that venting was necessary TEPCO made no attempt to re-establish the network of radiation monitors around the site perimeter that were disabled from lack of power. This violation of public responsibility and trust meant that it was impossible to adequately assess/measure risk to the public during the critical first week of the accident.

There was no system put in place to monitor conditions at the plant, given that it was too dangerous for workers on-site to do this, resulting in confusion over how the situation was progressing/deteriorating.

Offers of outside help and equipment were refused despite the fact that TEPCO lacked adequate equipment and trained personnel.

Plant workers were neither adequately trained nor equipped for safely and effectively carrying out their duties.

All of the above has led to confusion, misinformation, and an ad-hoc response that exacerbated an already terrible situation, unnecessarily endangered public safety and the safety of those tasked with working on the site. TEPCO in particular deserves neither the benefit of the doubt nor public trust. The government response, as the steward of the public interest, has not effectively mitigated TEPCO's failures. After all this the public will be asked to foot the bill for damage and cleanup and to suffer the various risks and ramifications of the accident for decades to come. [That said, there is also public responsibility in a democracy to make sure that public officials are doing their jobs, and consumers who rely on/expect 24hr electricity should understand that this requires acceptance of some risks and costs.]

I concede that everything you say about TEPCO may be true. On some of it, it is probably true about US plants, Russian plants, German plants and everywhere else. If they knew that they had underestimated the threat of seismic events, or tsunamis and did nothing about it they should be held to blame. If anything good can come from this tragedy it will be from rethinking our vulnerabilities and taking action to make our plants even safer.

i just think that right now, our concentration should be focused on what can be done to stabilize the plants and minimize the threat to the public. That is much harded than pointing fingers and criticizing the people who are there. We have no choice but to work with TEP
CO and Japanese leaders. Keep the thumbscrews and rack handy, their time will come.

 

[Fairweather]

You cannot focus neutrons and gamma rays to make an image on film. (X-ray imaging works because the source is point-like; there are no lenses involved in image formation.)

Gamma Ray detectors and imaging systems can be fabricated using tungsten collimators and detector arrays. See http://hesperia.gsfc.nasa.gov/hessi/index.html

 

[etudiant]

I concede that everything you say about TEPCO may be true. On some of it, it is probably true about US plants, Russian plants, German plants and everywhere else. If they knew that they had underestimated the threat of seismic events, or tsunamis and did nothing about it they should be held to blame. If anything good can come from this tragedy it will be from rethinking our vulnerabilities and taking action to make our plants even safer.

i just think that right now, our concentration should be focused on what can be done to stabilize the plants and minimize the threat to the public. That is much harded than pointing fingers and criticizing the people who are there. We have no choice but to work with TEP
CO and Japanese leaders. Keep the thumbscrews and rack handy, their time will come.

In that context, is there anything material that TEPCO is not doing that experts on this blog feel they need to do?

Surprisingly, the site is still very thinly staffed, about 500 people versus a normal complement of 4- 5000 reported in the Mainichi Daily News here:
http://mdn.mainichi.jp/mdnnews/news/20110325p2a00m0na014000c.html

If the site does indeed have only a skeleton staff, it surely indicates that no dramatic initiatives should be anticipated. So the facilities are expected to ride out the cyclone season largely as they are. There are not enough people to do much to help.

 

[AntonL]

On the last page of this http://www.meti.go.jp/press/2011/04/20110419002/20110419002-2.pdf" the route to transfer the highly radio active water is shown.

This route is through the turbine halls 3 and 4 and the pipes are flexible plastic pipes with metallic spiral for support.

How does plastic hold up to high radiation? will it go brittle or loose strength?

Is it wise to route highly radioactive water through what is possibly a fairly uncontaminated area, in case a leak springs. There seems to be concern regarding the couplings as they tied down and double wrapped as added precaution.

 

[robinson]

Can't verify any of this yet, but if true, quite interesting.

Japan admits daily radioactive release from Fukushima many times higher than previously announced — Nuclear commission blames calculation error

http://enenews.com/daily-radioactive-release-from-fukushima-is-150-times-higher-than-previously-announced-154-trillion-becquerels-released-everyday
http://ex-skf.blogspot.com/2011/04/fukushima-i-nuke-plant-154.html

 

[etudiant]

Can't verify any of this yet, but if true, quite interesting.

Japan admits daily radioactive release from Fukushima many times higher than previously announced — Nuclear commission blames calculation error

http://enenews.com/daily-radioactive-release-from-fukushima-is-150-times-higher-than-previously-announced-154-trillion-becquerels-released-everyday
http://ex-skf.blogspot.com/2011/04/fukushima-i-nuke-plant-154.html

The discussion on the scale of the emissions is somewhat moot, imo, because the reality of radiation cannot be hidden.
Japan is beginning to have summer weather, with inland winds and frequent rains. If the site continues large scale emissions, the Japanese authorities will need to further expand the evacuation zone.

 

[dh87]

Just because high dose material has been found on the site is not surprising. The destroyed building next to the unit 3 reactor building is the radwaste building. Also I would not be suprised if the u3 and u4 fuel pool demineralizers were damaged in the explosions. Radioactive does not mean fuel is flung around the site. It doesn't take a lot of co60 to provide a 1 sievert source.

I agree with this. TEPCO says that so far the released radioactivity is around 10,000,000 Curies (http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/f12np-gaiyou_e.pdf). As I calculated a couple pages back, this 900 mSv/hr object is a few Curies. It would be stunning if there weren't things this hot. It's not an indication that the fuel has escaped.

 

[com.oligarchy]

DH87
What difference does it make
its the same effect to living things
on this planet

 

[rowmag]

NHK TEPCO says the workers were exposed to 3.17 millisieverts of radiation during the clean-up and the concrete block has been stored safely in a container with other debris.

If they take 3.17 mSv by using a "remote-controlled rubble removing equipment" the radiation in that area must be enormous.

According to Yomiuri, it was not remote-controlled equipment, it was manned equipment that was used:

http://www.yomiuri.co.jp/feature/20110316-866921/news/20110423-OYT1T00654.htm

It was discovered on the 20th, and put into the container on the 21st.

As for the source, it is thought to be related to the hydrogen explosion of Unit 3.

 

[Jorge Stolfi]

I created a rough model of Fukushima Daiichi Unit #1 using the free raytracing program POV-Ray.

http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/Main.html

Unit #1 was the only one for which I had some reliable blueprints. If I had blueprints of the other units, I could consider doing them too...

Enjoy.

 

[NUCENG]

In that context, is there anything material that TEPCO is not doing that experts on this blog feel they need to do?

Surprisingly, the site is still very thinly staffed, about 500 people versus a normal complement of 4- 5000 reported in the Mainichi Daily News here:
http://mdn.mainichi.jp/mdnnews/news/20110325p2a00m0na014000c.html

If the site does indeed have only a skeleton staff, it surely indicates that no dramatic initiatives should be anticipated. So the facilities are expected to ride out the cyclone season largely as they are. There are not enough people to do much to help.

At present workers are trying to cool and stabilize reactors and fuel pools.

They are exploring buildings with robots to gather information about damage.

They are clearing debris from the site that interferes with areas they will use to restore power and find out what systems may still be operable.

They are allowing time to reduce dose rates.

They are limiting the number of people on site to reduce the number of people getting emergency doses to a minimum.

They are testing remote control equipment and some methods like spraying a type of sealent to keep down dust and airborne doses.

They have issued a roadmap for future actions.

They have a lot of foreign "help" to consider.

If they were providing more information, forums such as this one might be able to provide a form of validation and technical review of that information.

Other than that I can't think of anything else they should be doing. You raise the question of cyclones. In Japan the word is taifun or typhoon. That is a legitimate concern. Torrential rain and winds could further damage the buildings and further disperse radioactivity to the environment. But until they have a better understanding of damage, it could be counterproductive to start bracing or repairing buidings. Getting debris cleared up will reduce potential missile damage.

Your question is a good one. What else should they be doing?

 

[MiceAndMen]

I created a rough model of Fukushima Daiichi Unit #1 using the free raytracing program POV-Ray.

http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/Main.html

Unit #1 was the only one for which I had some reliable blueprints. If I had blueprints of the other units, I could consider doing them too...

Enjoy.

Pretty good, Jorge, although I would dispute that fig_un1_pools_and_walls.png shows the correct layout of the pools. There has been no confirmation that the smallest pool in the picture actually exists separately from the SFP in any of the reactor buildings.

I was going to do a large-scale plant layout in 3D until I saw someone beat me to it.
http://www.turbosquid.com/3d-models/c4d-nuclear-power-plant-fukushima/594020
I downloaded some of the jpegs from that page and saw many inaccuracies. The overall work is good, but not precise enough for my liking. The guy even duplicated the paint scheme on the side of the buildings! For that price, I would expect near perfection, and even if everything was perfect I don't think I would pay $299 for the model

 

[rowmag]

Don't know if these have been mentioned:

"The government is considering building an underground barrier near the Fukushima No. 1 nuclear power plant to prevent radioactive material from spreading far from the plant via soil and groundwater, a senior government official said."

Reactor 1 already half-entombed with water:
"At a press conference held Friday, TEPCO said it believed pressure suppression pools at the bottom of the No. 1 reactor's containment vessel were full of water, and that the top section of the containment vessel was about half full. Under normal circumstances, the pressure suppression pools are about 50 percent full with water."

http://www.yomiuri.co.jp/dy/national/20110423dy01.htm

 

[TCups]

I agree with this. TEPCO says that so far the released radioactivity is around 10,000,000 Curies (http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/f12np-gaiyou_e.pdf). As I calculated a couple pages back, this 900 mSv/hr object is a few Curies. It would be stunning if there weren't things this hot. It's not an indication that the fuel has escaped.

10,000,000 Curies?! Really? The equivalent radioactivity of ten thousand kilograms of radium?! Ten metric tonnes?!

What sort of things accumulate in precipitators? Co 60? Can someone tell us more about "radwaste buildings" please? Does contamination from the radwaste building fit with these early measurements? (see attached)

http://i306.photobucket.com/albums/nn270/tcups/4000d390.png

 

[Borek]

My conviction is that decision making and technical matters are intimely intricated when a crisis like the Fukushima crisis is concerned. Dealing with the latter while ignoring the former can only provide a biased vision of the situation. Therefore I would rather leave than collaborate to a biased form of reporting.

As I explained earlier, feel free to discuss other matters in different threads, you can start them either in Nuclear Engineering or Politics & World Affairs subforums.

It is not about censorship, it is about keeping some order in the discussion. Putting everything into one thread means mess.

 

[dh87]

10,000,000 Curies?! Really? The equivalent radioactivity of ten thousand kilograms of radium?! Ten metric tonnes?!

Well, yes. TEPCO says 3.7e+17 Bq, and there's 3.7e+10 Bq/Ci. Radium 226, on which the unit is based, has a 1600-year half-life, resulting in that large mass that you quote (since becquerels and curies are both units of decays per unit time). If you calculate for I-131, you'll get a much smaller mass.

The number that TEPCO announced doesn't appear to include the radioactivity that's in the 70,000,000 liters of water sloshing around the reactors, nor the 100,000 Curies (4,700 TBq) that has already been released into the Pacific Ocean.

 

[tyroman]

From Cainnech's post #4653:
https://www.physicsforums.com/showpost.php?p=3262389&postcount=4653

"TEPCO suspects that the water leaked from the RPV is leaking through the cracks in the wall that separates the Reactor 3 turbine building and the Reactor 4 turbine building."

Could the features I have noted in the photos below possibly be evidence of the size of the "cracks" between the two turbine buildings? Does anyone know where these central control rooms are located?

From:
http://cryptome.org/eyeball/daiichi-npp3/daiichi-photos3.htm
See: pic41.jpg [EDIT: sixth photo from top]
Caption of above:
"In this photo released by Tokyo Electric Power Co., the central control room of Unit 3 is pictured after lights went on while that of Unit 4, left side, is still dark at the Fukushima Dai-ichi nuclear power plant in Okumamachi, northern Japan Tuesday, March 22, 2011. (Tokyo Electric Power Co. via Kyodo News)"

If my annotations on pict41[zoom].JPG are correct, there has been a significant dislocation caused by the quake.

.

 

[PietKuip]

Just because high dose material has been found on the site is not surprising. The destroyed building next to the unit 3 reactor building is the radwaste building. Also I would not be suprised if the u3 and u4 fuel pool demineralizers were damaged in the explosions. Radioactive does not mean fuel is flung around the site. It doesn't take a lot of co60 to provide a 1 sievert source.

I do not know what fragments of demineralizers might look like, but I would be surprised if it could be described as pieces of concrete.

This is not something that would be lying about. If it is a normal part of the plant, it would be shielded by a lot of concrete, steel, or lead.

It might also be something that radioactive cesium or iodine vapors had sublimated on, or that a radioactive liquid had evaporated from, after the earthquake before the explosion.

So there are several possibilties. Maybe they did find out what it was - they moved it a day after it had been found.

 

[|Fred]

What might be a reasonable estimate of the extra dose in Tokyo? I think 1 mSv might be a reasonable order of magnitude (about a year of 0.1 microSievert per hour, on average). With 10^7 people that gives 10^4 man-Sievert, about 100 deaths.

If I understood the couple of paper I read, right (UNSCEAR). Sources, Effects, and Risks Of Ionizing Radiation, BEIR, ircrp, EPA 402-R-93-084, and envhper00536-0363.
Basicaly we have a measured risk factor from one shoot ionization >0.1 Sv <1Sv between 0.11 et 0.06 % for adults. When it comes to over time rather that one shoot either we arbitrary reset the counter every year or we apply a damping factor and the risk factor is dropped to 0.05 to 0.02. (doing so we diverge already from the LNT)

But this is still for >0.1 Sv <1Sv dose , as for extra the 1mSv/year we don't know as we rather have data suggesting it won't make a difference.

 

[|Fred]

I was going to do a large-scale plant layout in 3D until I saw someone beat me to it.

that's impressive 3d skills

Japan admits daily radioactive release from Fukushima many times higher than previously announced — Nuclear commission blames calculation error

It was my understanding that when you were talking of Becquerel one should always specify isotope, If I understood right INES requested(converting cesium amount into iodine equivalent).
This will give a bigger number alright but this has nothing to do with calculation error but only with the difference of half live between the cesium and iodine.

I'm I failing somewhere ? Is the press making something hudge out tomatoe/tomatoe

ps: what I do not understand is why the need to convert converting cesium amount into iodine equivalent.. regardless of the cesium or iodine 1 Becquerel will produce the same amount of ionization energy wouldn't it?

 

[razzz]

Don't know if these have been mentioned:

"The government is considering building an underground barrier near the Fukushima No. 1 nuclear power plant to prevent radioactive material from spreading far from the plant via soil and groundwater, a senior government official said."

Reactor 1 already half-entombed with water:
"At a press conference held Friday, TEPCO said it believed pressure suppression pools at the bottom of the No. 1 reactor's containment vessel were full of water, and that the top section of the containment vessel was about half full. Under normal circumstances, the pressure suppression pools are about 50 percent full with water."

http://www.yomiuri.co.jp/dy/national/20110423dy01.htm

What a logistics nightmare that would be. This site was chosen for it's bedrock almost an outcropping which means the foundations were poured on stable rock and not sand or organic soils. If they didn't prepare the bedrock by actually blasting or jack-hammering to level an area before laying forms and pouring concrete directly on bedrock then they filled on top of the bedrock with smaller rocks to make level a pad for pouring a monolithic floating building(s).

Now they want to dig back down to bedrock and pour concrete footings (walls) directly attached to bedrock in some form or fashion for a watertight perimeter/barrier around all four units. If the original geological reports showed little or no fractures in the bedrock then it might be possible provided you can deal with contaminated ground and seawater entering the excavation until you can get a clean prepared surface to pour concrete on or into. Might even drill into bedrock for anchoring down and/or notching to place a proper water barrier.

At least might be done in a suitable working environment away from 3 cores and one pond if contaminated water can be kept under control by de-watering (more pumping into the ocean). Not as desperate a plan as dropping seawater from choppers. Securing SFP 4 still takes precedences the way I see it. Unit 1 seems to at least hold water, 2 & 3 can only be flooded while waiting for consistent water levels and cool downs. Either the water levels go up or the fuel rods meltdown to form a happy medium (steam versus water cooling).

For now I would think higher liquid and ground contamination readings in the event of water encasement lessening the air contamination.

 

[clancy688]

Well, yes. TEPCO says 3.7e+17 Bq, and there's 3.7e+10 Bq/Ci.

That number is already converted into I131-equivalence. The actual, measurable activity is 1.4e+17 Bq.
But that's still 40% of 10.000.000 Curie.

@tsutsuji
Your leaving of this forum / discussion really is a pity. I always liked to read your posts, they were well structured and you always had good sources at hand.

 

[MiceAndMen]

From Cainnech's post #4653:
https://www.physicsforums.com/showpost.php?p=3262389&postcount=4653

"TEPCO suspects that the water leaked from the RPV is leaking through the cracks in the wall that separates the Reactor 3 turbine building and the Reactor 4 turbine building."

Could the features I have noted in the photos below possibly be evidence of the size of the "cracks" between the two turbine buildings? Does anyone know where these central control rooms are located?

From:
http://cryptome.org/eyeball/daiichi-npp3/daiichi-photos3.htm
See: pic41.jpg [EDIT: sixth photo from top]
Caption of above:
"In this photo released by Tokyo Electric Power Co., the central control room of Unit 3 is pictured after lights went on while that of Unit 4, left side, is still dark at the Fukushima Dai-ichi nuclear power plant in Okumamachi, northern Japan Tuesday, March 22, 2011. (Tokyo Electric Power Co. via Kyodo News)"

If my annotations on pict41[zoom].JPG are correct, there has been a significant dislocation caused by the quake.

.

I doubt very much that the control centers for 2 reactors would share the same physical space. One wouldn't want the situation of one reactor to distract the operators of another. The caption on that photo is probably incorrect.

Having said that, the floor does look dislocated. It could be due to structural damage from the earthquake, or simply part of a raised floor that collapsed. Many mainframe computer rooms have raised floors with space underneath for cables. It wouldn't surprise me if NPP control room floors are similar. In any case, as I said above, I find it highly unlikely that 2 control rooms would be adjacent to each other in a single enclosed space. There are no great building layout plans or diagrams that show where the individual control rooms are for each reactor that I have seen.

 

[kujala]

A couple of notes from this good document:
http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/f12np-gaiyou_e.pdf

1. Page 22: "Treatment of sub-drainage water after being pumped up"
So this is really all TEPCO can do about the underground water. They must pump it up from the unit 1 - 4's sub-drainage pits and handle it.
But please note this only concerns the water that has been accumulated in the sub-drainage pits.
I guess the contaminated water from the plant may find some routes below the level where the sub-drainage systems are working. And below that level you cannot really do anything.
And there is also a massive load of tsunami waters in the area which has affected the groundwater levels. What happens to the sub-drainage systems if there is "too much" water for them to handle? Anybody knows?
I am really amazed by the fact that TEPCO has been so quiet about the level of water in the unit 1 - 4's sub-drainage pits and also that they have not stated when they are going to empty them.

BTW, on the 5th of April they emptied 1 500 tons of water from the unit 5 - 6's sub-drain pits to the sea, according to IAEA. This water was low-level contaminated:
http://varasto.kerrostalo.huone.net/salaojat_1.png

2. Page 28: A really cool picture about how far the tsunami waters traveled in the Daiichi and Daini plants.

 

[|Fred]

I doubt very much that the control centers for 2 reactors would share the same physical space. .

they do , you can google it out :)

"photo shows the control room for the No.3 and No.4 reactors at the quake-hit Fukushima Daiichi Nuclear Power Station in Fukushima Prefecture at 11:28 p.m. on March 22, 2011. Lighting has been restored in the right side of the control room serving the No.3 reactor, while the left side remained dark for the No. 4 reactor. (Photo provided by Tokyo Electric Power Co.)(Kyodo)"

 

[dh87]

It was my understanding that when you were talking of Becquerel one should always specify isotope, If I understood right INES requested(converting cesium amount into iodine equivalent).
This will give a bigger number alright but this has nothing to do with calculation error but only with the difference of half live between the cesium and iodine.

I'm I failing somewhere ? Is the press making something hudge out tomatoe/tomatoe

ps: what I do not understand is why the need to convert converting cesium amount into iodine equivalent.. regardless of the cesium or iodine 1 Becquerel will produce the same amount of ionization energy wouldn't it?

Not exactly. A Bq is one decay per second of whatever is decaying. For tritium, one decay is one beta particle with an energy of 5.7 keV. For phosphorus-32 (chosen because it's simple), one decay is a beta particle with an energy of 1700 keV. These are very different amounts of ionization energy per decay and have vastly different biological effects. Cs-137 and I-131 are similar in total decay energy (around 1000 keV), but the pathways are complicated with branches and betas and gammas. I'm not sure how to compare them.

 

[MiceAndMen]

they do , you can google it out :)

"photo shows the control room for the No.3 and No.4 reactors at the quake-hit Fukushima Daiichi Nuclear Power Station in Fukushima Prefecture at 11:28 p.m. on March 22, 2011. Lighting has been restored in the right side of the control room serving the No.3 reactor, while the left side remained dark for the No. 4 reactor. (Photo provided by Tokyo Electric Power Co.)(Kyodo)"

Interesting if true, but the dark side of the room on the left looks nothing like the right side. Look at the ceiling, there is no symmetry whatsoever. Furthermore, reactor #4 trailed behind #3 in construction and operation by 1.5 years. One would have to show more than a single photo to make be believe it is true. Always happy to be proven wrong

 

[Dmytry]

I doubt very much that the control centers for 2 reactors would share the same physical space. One wouldn't want the situation of one reactor to distract the operators of another. The caption on that photo is probably incorrect.

Why so? It would make commercial sense; during normal operation it would allow same number of trained staff to run 2 reactors rather than one. Sure, during a disaster that is not very good, but during normal operation that reduces staffing requirements.

 

[MiceAndMen]

Why so? It would make commercial sense; during normal operation it would allow same number of trained staff to run 2 reactors rather than one. Sure, during a disaster that is not very good, but during normal operation that reduces staffing requirements.

It does not make safety sense.
http://www.nrc.gov/reactors/operating/ops-experience/control-room/ml013100014.pdf

Releases of hazardous chemicals can result in the control room becoming uninhabitable.

Do you really think an operator would risk having to abandon control operations for 2 reactors because 1 had a problem? I sure don't. It would be madness.

Edit: OK, I guess it does happen.

http://books.google.com/books?id=XI...=reactors share "single control room"&f=false

If I was in charge, it would be prohibited. I think it's a really dumb idea, and if regulators agree to an arrangement such as that, then the regulators IMO need to be replaced.

 

[clancy688]

It was my understanding that when you were talking of Becquerel one should always specify isotope, If I understood right INES requested(converting cesium amount into iodine equivalent).
This will give a bigger number alright but this has nothing to do with calculation error but only with the difference of half live between the cesium and iodine.

I'm I failing somewhere ? Is the press making something hudge out tomatoe/tomatoe

Yeah, you're right. If I understand the press reports correctly, there are releases of 0.69 TBq I131 and 0.14 TBq C137. That's the measurable activity. So all in all, you have 0.83 trillion decays per second, most of it I131. Telling that there are releases of <1 TBq/h is not wrong. If you convert it into equivalence, you'll get 6.4 TBq/h... in my opinion there's no mistake.
I get the impression that soon there will be some chaos regarding actual activity or I131-equivalence activity in the media.
They should just report I131 and C137 separately...

ps: what I do not understand is why the need to convert converting cesium amount into iodine equivalent.. regardless of the cesium or iodine 1 Becquerel will produce the same amount of ionization energy wouldn't it?

The conversion is used to get a standard of how dangerous an isotope is. Krypton-85 for example emits beta particles and has a half time of 10 years, plus there's much of it inside a nuclear reactor. But it isn't very dangerous because it has a very, very fast biological half life and stays in the atmosphere without contaminating anything.

Then we have I131 and C137. If there's a mass of I131 with an activity of 1000 Bq and a mass of C137 with an activity of 1000 Bq, then both are equally dangerous. But after a year there's virtually 0 Bq of that I131 left, so it's not dangerous anymore. But the 1000 Bq mass of C137 has still an activity of nearly 1000 Bq - because it has a half time of 30 years. And because there are MUCH more atoms released as for I131.

Basically, converting activity into an equivalence is done to express the danger of an isotope over a large timeframe - while the activity in Bq only describes the danger during the exact second of the measurement.