Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[NUCENG]

I wonder if anybody can answer the question why the control rod arrangements appear to be such a complicated construction with individual drives for each rod (as it would appear to be from the diagrams I have seen). Am I correct in assuming that the control rods are pushed up hydraulically, and if so, isn't that a tricky arrangement when power is lost, or hydraulics damaged, such as in an earthquake. Also, how does one know whether the control rods have been engaged completely?
Wouldn't a design be more logical where the entire core is pushed up from a grid of control rods that is fixed lower in the vessel, i.e. where loss of power would result in stopping the reaction as a result of gravity?
Is it perhaps the case that control rods are adjusted individually during normal operation, i.e. that they may be inserted at individually different levels, and if so, what type of instrumentation is available to monitor that?

Control rods are used individually in BWRs to adjust core reactivity as fuel is fissioned. It allows operators to shape the power density in a core to use as much of the loaded uranium as possible. If unlatched during operation a control rod will drift into the core due to reactor pressure.

PWRs use banked rod controls but also use the solution of boron in the water to adjust reactivity.

BWRs don't used boron during operation because the boiling water might result in plating out boron.

 

[jensjakob]

They are not looking for such evidence. The IAEA seems to be guessing in the same way as we: http://www.bloomberg.com/news/2011-03-30/record-high-levels-of-radiation-found-in-sea-near-crippled-nuclear-reactor.html

Tepco is just feeding the IAEA with the same reams of numbers they give us. But one needs to get some non-routine measerents, some firm data about whether the fuel is (intermittently) critical or not. If decent neutron detectors are not available, there are low-tech methods, like dangling wedding bands in suspected places: the gold will become radioactive if there is a neutron flux. Or one could use the manganese in ordinary batteries.

This is not difficult. I cannot understand how the key information about possible chain reactions is still a question more than two weeks after the accident.

Money... Liabilities... We are talking extreme big business here, not just Fukushima or TEPCO are on stake - but the whole NPP industry.

I am not a doom-sayer or anti- nor pro-nuke, just working for the factual truth.

 

[NUCENG]

Nuceng, the containment has been filled with water.

I thought so, and even said so here on the forum but Astronuc indicated that he hadn't seen that report. I went back and couldn't find a clear statement of that from TEPCO. Did you find a source confirming they did containment flooding?

 

[NUCENG]

They are not looking for such evidence. The IAEA seems to be guessing in the same way as we: http://www.bloomberg.com/news/2011-03-30/record-high-levels-of-radiation-found-in-sea-near-crippled-nuclear-reactor.html

Tepco is just feeding the IAEA with the same reams of numbers they give us. But one needs to get some non-routine measerents, some firm data about whether the fuel is (intermittently) critical or not. If decent neutron detectors are not available, there are low-tech methods, like dangling wedding bands in suspected places: the gold will become radioactive if there is a neutron flux. Or one could use the manganese in ordinary batteries.

This is not difficult. I cannot understand how the key information about possible chain reactions is still a question more than two weeks after the accident.

I can only guess with the rest of you. Neutron rediation is a little more difficult to detect because it isn't a charged ion. But plants have detectors. With all the IAEA, UN, and foreign support on the ground it would take more than TEPCO to hush that up.

 

[artax]

some interesting stuff here with analysis of one of the heli flyover videos by a Japanes Prof.
The 'GOOD NEWS' stated towards the end of this is just embarassing and SO Japanese!



It seems to me they need to build a new sea wall around the discharge to sea outlet pipes, leaving a big isolated lake of sea water, and then simply set up massive 5 inch or so pipes supported by the turbine building roof to all the 4 reactors, then just circulate the water so it's not going out to sea.
Probably though the sea wall construction would be a 3 month massive civil engineering project!

 

[|Fred]

I thought so, and even said so here on the forum but Astronuc indicated that he hadn't seen that report. I went back and couldn't find a clear statement of that from TEPCO. Did you find a source confirming they did containment flooding?

I know ;à)
I think I did , may be you missed my post ... It's a bit hard to follow since the document published by the JAIF, language is pretty missleading as It seems toi me that they states present situation rather that timelined action

in unit 1 the pressure of the core was dropped from 7MPa to 0.8MPa within 12 hours of the accident as a consequence (i think) the pressure of the containment raised from 0.1MPa to 0.8MPa (this lead to leak from the top of the containment vessel) and likely the first blash.

We know that on the 15th http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300171089P.pdf Sea water injection to Containment Vessel unit 1 was "Done"

some time betwen the the 16th and the 17th it was decided to inject water on unit 3
(continuing)(to be decided)(to be decided)
http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300273535P.pdf
(continuing)(to be decided)(continuing)
http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300322727P.pdf


If I'm to trust the jaif document with a grain of interpretation

1 and 3 containment are filled with water not 2.. unit 2 is the only one with a secondary containment structure almost fully standing..co incidence?

 

[artax]

There's a good video on youtube called inside the sarcophagous. They were pretty concerned about the contents reforming a shape that was 'critical' at chernobyl months after the accident, and went inside to investigate exactly where all the fuel had gone. When they finally saw inside the core it was empty!

 

[AntonL]

I hope I am not double posting -The same photos with a bit more detail

Unit 2 also had quite a blast in the basement area - look at the roof of the 1 story structure on North side of the reactor building (left hand side)

Tepco always reported explosion by Torus with possible Torus damage, but it was quite a bang judging from the photo and No.2 has the highest contaminated water in basement.

(AP Photo/AIR PHOTO SERVICE) MANDATORY CREDIT
Unit 3 & 4 in next post

 

[AntonL]

and here Units 3 & 4 (AP Photo/AIR PHOTO SERVICE) MANDATORY CREDIT

 

[artax]

There's a lot of debris on that 1 storey building, so the damage is likely to be from the number 1 blast?
However there is a strange line down one side of unit 2, the side with the agping hole venting steam, anyone else noticed that?

 

[AntonL]

Questions and comment from within Japan
be interesting to get hold of GE report being referenced

When reading the below remember that the reactors had 1 hour precooling and rest heat generation would have been reduced to [STRIKE]50 to 65%[/STRIKE] 30% of the values so the times shown below could be tripled or more (1 hour cooling) (Edit: I must check exact times and revise later)

Primary total loss of power, safety regulations intended to make the U.S. 30 years ago.

16 hours 39 minutes 31 March 2011
Print

　For the same type of reactor Fukushima Daiichi Nuclear Power Station TEPCO, 1981 - U.S. research institutions in 1982, conducted a simulation of all power is lost, report to the U.S. Nuclear Regulatory Commission (NRC) submitted had been found. Exposure of the calculated fuel, hydrogen generation, and melt the fuel scenario similar to the course of this incident. Although the use of NRC safety regulations which, as Japan did not expect such as early recovery and power lines.

　This simulation is modeled on a nuclear reactor Brownsferry, conducted by the U.S. Oak Ridge National Laboratory. The output of approximately 110 million kilowatts, Fukushima Daiichi nuclear power plant - a General Electric as the No. 5 (GE) of boiling water mark "I" is the furnace.

　Fukushima Daiichi nuclear power plant like this, "the loss of emergency diesel generator and an external AC power, battery operated emergency" and assume that, the battery time available, the health of an emergency cooling system calculated separately and in some cases.

　If available, 4 hours battery, 5 hours after the start of a power failure "exposed" fuel, after 5.5 hours, "the fuel reached at 485, may also occur Hydrogen", after six hours, "the molten fuel (meltdown) start ", after seven hours," the lower the pressure vessel is damaged, "eight hours after" damage containment "that the results came out.

　In a separate calculation of the institute was available for 6 hours, 8 hours after exposure "fuel", 10 hours after the "start meltdown", 13 hours after "damage containment" was.

　Meanwhile, Fukushima Daiichi, the loss of power from an external source during earthquakes, but switched to diesel generators for emergency stops and the generator about an hour after the tsunami, the power supply as Battery DC emergency to. Conditions were simulated in the same condition as at this time.

　8 hour battery is available, unlike the simulation, but is almost the same sequence of events occurred. Also, the calculation is adopted, the Fukushima Daiichi nuclear power plant containment may already have lost their sanity.

　GE's Sato Akira consultant nuclear has been involved for years in maintaining boiling water affiliated with the "simulation is good enough at this time. Whether that is handed down the findings of these past power company just do not know "he said.

　Meanwhile, in Japan itself, assuming all power is lost, has been neglected.

　Nuclear Safety Commission in 1990, when the design review guidelines for determining the safety of nuclear power, "the long-term loss of all AC power source, power lines or recovery (again) because the facility is expected to AC power for emergency repairs There is no need to consider, "the idea that. But in reality, the earthquake and tsunami unusable in an emergency diesel generator power line also.

　Matsuura Shiyouzi Chairman Department of Nuclear Safety Research Association (Director, NSC yuan) is "a bad situation and that everything was good to think about unwritten. Meteorite (Inseki) and hit, and anything ask, can cope with dry, it's impossible, "he said. (Ichiro Matsuo, 磨 Komiyama Makoto)

Asahi Top Com

 

[Astronuc]

The human side of this event:

Workers Give Glimpse of Japan’s Nuclear Crisis
http://www.nytimes.com/2011/03/31/world/asia/31workers.html

A manager from the Tokyo Electric Power Company explained how the Fukushima Daiichi nuclear plant had been slammed by a mammoth tsunami and rocked by hydrogen explosions and had become highly radioactive. Some workers wept.
. . . .
Hundreds of firefighters, Self-Defense Forces and workers from Tokyo Electric Power convened at the sports training center, arguing long and loudly about how best to restore cooling systems and prevent nuclear fuel from overheating. Complicating matters, a lack of phone service meant that they had little input from upper management.

“There were so many ideas, the meeting turned into a panic,” said one longtime Tokyo Electric veteran present that day. He made the comments in an interview with The New York Times, one of several interviews that provided a rare glimpse of the crisis as the company’s workers experienced it. “There were serious arguments between the various sections about whether to go, how to use electrical lines, which facilities to use and so on.”
. . . .
In the interviews and in some e-mail and published blog items, several line workers expressed frustration at the slow pace of the recovery efforts, sometimes conflicting orders from their bosses and unavoidable hurdles like damaged roads. In many cases, the line workers want the public to know that they feel remorse for the nuclear crisis, but also that they are trying their best to fix it.

“My town is gone,” wrote a worker named Emiko Ueno, in an email obtained by The Times. “My parents are still missing. I still cannot get in the area because of the evacuation order. I still have to work in such a mental state. This is my limit.”
. . . .

Company management still wants to keep tight control on the flow of information from the company to the public (and government).

On March 14, workers were told that the assignment was dangerous and that they could opt out. Few did. Many workers felt duty-bound to go to Fukushima, particularly those with families who were directly affected by the earthquake and tsunami.

As was mentioned much of the infrastructure in the area was knocked out.

The local roads were slower going because parts of some streets had literally disappeared.

 

[artax]

That really brings it home doesn't it.

don't know if these are of any interest

http://photos.oregonlive.com/4450/gallery/fukushima_aerials/index.html

well this one is:-

http://photos.oregonlive.com/oregonian/2011/03/aerial_9.html

 

[NUCENG]

I know ;à)
I think I did , may be you missed my post ... It's a bit hard to follow since the document published by the JAIF, language is pretty missleading as It seems toi me that they states present situation rather that timelined action

in unit 1 the pressure of the core was dropped from 7MPa to 0.8MPa within 12 hours of the accident as a consequence (i think) the pressure of the containment raised from 0.1MPa to 0.8MPa (this lead to leak from the top of the containment vessel) and likely the first blash.

We know that on the 15th http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300171089P.pdf Sea water injection to Containment Vessel unit 1 was "Done"

some time betwen the the 16th and the 17th it was decided to inject water on unit 3
(continuing)(to be decided)(to be decided)
http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300273535P.pdf
(continuing)(to be decided)(continuing)
http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300322727P.pdf


If I'm to trust the jaif document with a grain of interpretation

1 and 3 containment are filled with water not 2.. unit 2 is the only one with a secondary containment structure almost fully standing..co incidence?

That's it! I remember the words "containment vessel" were in some press release, and interpreted that as containment flood. Thanks.

During initial stages after loss of cooling they would have controlled pressure by using safety relief valves to vent steam from the reactor vessel to the suppression pool where the steam would be quenched and the suppression pool would heat up. RCIC is a steam/battery supported system and would be used to add water to the vessel. Once the battery was exhausted, trouble begins. They still would have vented steam to the suppression pool until it reaced its temperature limit or began to boil. It would no longer be able to condense steam if boiling occurred and the drywell and contaiment pressure would rise. Before that reached design limits, operators would want to vent pressure to prevent major failure of the containment. They would write off the core to protect the containment and the public. SRVs would have moved hydrogen to the airspace of the torus/suppression pool. Venting would then release this into systems outside the primary designed to filter and release through the stack. That would increase the dispersion of radioactivity compared to a near ground release. US BWRs have a hardened vent capable of handling these pressures. If indeed the containment system reached 0.8 MPa it may have been over its design pressure and it may have leaked past the contaiment cap onto the refuel floor. These two cases may have some impact on where detonations ocurred.

There are blowout panels in the reactor building sides on the refuel floor. That may explain the two openings in the Unit 2 siding. They are primarily designed to vent steam line breaks, not hydrogen explosions.

 

[|Fred]

I remember reading from Jaif or Nisa (I unfortunately can not find the link again), the legislative paper regulating exceptional procedures in case of nuclear disaster and the raise on legal maximum radiation dose allow worker to conduct operation.
I clearly recall that although limit is raised from 20 or 50mSv/y to above 200, work commitment has to be voluntary.

Does it ring bells to similar legislation in the US ?


edit:
Sea water injection to core =>Done
Sea water injection to Containment Vessel =>Done
there are two lines implying they are two different things , do we agree that the "drywell" has been flood in 1 and 3 ?

 

[TCups]

There's a lot of debris on that 1 storey building, so the damage is likely to be from the number 1 blast?
However there is a strange line down one side of unit 2, the side with the agping hole venting steam, anyone else noticed that?

Yes. There were also previous close ups of Bldg 2 that show the cracks (pleural) as well as several small holes in the roof venting small amounts of smoke or steam, in addition to the sizable hole in the east face of Bldg 2 as I recall.

 

[NUCENG]

There's a good video on youtube called inside the sarcophagous. They were pretty concerned about the contents reforming a shape that was 'critical' at chernobyl months after the accident, and went inside to investigate exactly where all the fuel had gone. When they finally saw inside the core it was empty!

I have seen a 60 Minutes episode where the entered the plant exploring the lower levels of the building below where the reactor core was. They discovered a fossilized flow of melted sand (glass) and core materials that they have nicknamed the "elephant' foot." The most memorable thing on that show was that the Russians monitoring the plant tended to leave their personal dosimetry behind when they went inside the sarcophogus. They didn't want to get a dose that required them to leave the site.

That is similar to the lessons from Three Mile Island. In the midst of the event it was hard to get people to leave because they all wanted to help. Similarly, the stories of the "50 heroes" at Fukushima Daiichi.

 

[timeasterday]

I have seen a 60 Minutes episode where the entered the plant exploring the lower levels of the building below where the reactor core was. They discovered a fossilized flow of melted sand (glass) and core materials that they have nicknamed the "elephant' foot." The most memorable thing on that show was that the Russians monitoring the plant tended to leave their personal dosimetry behind when they went inside the sarcophogus. They didn't want to get a dose that required them to leave the site.

That is similar to the lessons from Three Mile Island. In the midst of the event it was hard to get people to leave because they all wanted to help. Similarly, the stories of the "50 heroes" at Fukushima Daiichi.

I remember one part of the Youtube video where they describe getting a sample of the elephant's foot by shooting at it with an AK-47!

 

[Gilles]

how to say without saying...

http://www.bloomberg.com/news/2011-03-30/record-high-levels-of-radiation-found-in-sea-near-crippled-nuclear-reactor.html

Japan’s Nuclear and Industrial Safety Agency said there’s no possibility of uncontrolled chain reactions.

they exclude the possibility of uncontrolled chain reactions , but not of chain reactions ! obvisously , if some occur, they can be only transient and without much power, since the whole thing has not yet exploded. The intrinsic kinetics of chain reactions implies a negative feedback adjusting the level close to near-criticality. I'm not sure that the scenario I sketched https://www.physicsforums.com/showpost.php?p=3214771&postcount=1697" :) ) but something similar should happen if the presence of neutrons in confirmed.

 

[TCups]

EXTENT OF DAMAGE TO REACTOR BUILDINGS DUE TO EARTHQUAKE?


Have there been any reports of the extent and types of earthquake damage that occurred at other regional NPP's that didn't suffer catastrophic consequences of complete loss of power?

Perhaps this point was already made, but if so, I make it again. A 9.0 earthquake, in and of itself, could do significant damage to the reactor buildings. The scenarios I and others have considered in most detail follow the consequences of complete loss of all power and subsequent events related to the reactor vessels, primary containment, and spent fuel pools.

The chain of events at Fukushima with the rapid arrival of the tsunami and complete loss of power were such that, if done, there has been little or no reporting of a primary assessment of damages or likely damages due solely to the magnitude of the earthquake. Significant lateral thrusting occurred.

I am reminded of the external crack visible on Bldg 2 and must wonder if they are blast or earthquake-related, or more likely, a combination of both.

Also, in cross-section, the arrangement of a massive concrete and steel primary containment structure nested atop a huge underground torus leads me to wonder what damages the quake might have caused by the extreme forces of lateral thrusting where the two structures meet, so to speak.

Some knowledge of the specific types and locations of damages that might have been in play at Fukushima at the time power was lost would surely be helpful in sorting out what has followed.

 

[chrget]

[...]
be interesting to get hold of GE report being referenced

Hmmmm, might it be http://www.osti.gov/bridge/purl.cover.jsp?purl=/6402578-Rr9xTe/", by any chance?

Regards,
Chris.

 

[AntonL]

Hmmmm, might it be http://www.osti.gov/bridge/purl.cover.jsp?purl=/6402578-Rr9xTe/", by any chance?

Regards,
Chris.

Chris welcome - one of the most contributing first posting - looking forward to your next contribution

 

[artax]

We need more images to discuss, that bit was fun.
here's a higher res one
http://cryptome.org/eyeball/daiichi-npp/pict10.jpg
and

http://cryptome.org/eyeball/daiichi-npp/pict7.jpg

and no 4

http://www.journal.lu/wp-content/uploads/2011/03/35_063_2col_NB_p09_839862.jpg
and brownsferry construction

http://i700.photobucket.com/albums/ww1/indoorcarnivore/Browns_Ferry_Unit_1_under_construction.jpg

 

[chrget]

Chris welcome - one of the most contributing first posting - looking forward to your next contribution

Thank you very much. I doubt I can offer all that much input regarding the physical aspects, though. So it was more or less a lucky Google hit.

Speaking of which, I think I found the actual document in question, which is only referenced by the one I mentioned earlier: http://www.ornl.gov/info/reports/1981/3445600211884.pdf"

Regards,
Chris.

 

[TCups]

EARTHQUAKE DAMAGE AT THE TORUS - PRIMARY CONTAINMENT INTERFACE?

With the very limited knowledge I have regarding building to earthquake code, I seem to recall that one of the fundamental approaches is to build foundations that allow for lateral movement of the ground under the building with foundations that "float".

With the limited information available to me regarding the construction of the BWR's of the type at Fukushima, it would appear that a huge torus suppression pool underground and a massive concrete and steel primary containment nested in it would not tend to "float" side to side with the lateral forces of a 9.0 earthquake. Instead, it would seem to me that the arrangement would be more like a bowling pin sitting in a bowl. One could hypothesize that the most likely stress point might be where the torus and primary containment meet.

This might help explain

1) failure of Unit 2 in the torus suppression pool region
2) some of the explosive damages in the lower levels of Unit 3

But it would not explain

3) explosive damages in the lower levels of Unit 4

Comments?

 

[PietKuip]

how to say without saying...

http://www.bloomberg.com/news/2011-03-30/record-high-levels-of-radiation-found-in-sea-near-crippled-nuclear-reactor.html



they exclude the possibility of uncontrolled chain reactions , but not of chain reactions ! obvisously , if some occur, they can be only transient and without much power, since the whole thing has not yet exploded. The intrinsic kinetics of chain reactions implies a negative feedback adjusting the level close to near-criticality. I'm not sure that the scenario I sketched https://www.physicsforums.com/showpost.php?p=3214771&postcount=1697" :) ) but something similar should happen if the presence of neutrons in confirmed.

I looked att the graphs (! very rare in Tepco publications) in http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110330e13.pdf

The ratios of the isotope concentrations are varying a bit, but there is no obvious faster decline of the short-lived ones in the last week. Which may indicate that fission is ongoing.

 

[curie]

Thanks curie,

So these methods can detect all radio-isotopes, (plutonium, cesium, etc...) in soft tissue, like the lung, thyroid, etc... ?

Rhody...

A combination of biological monitoring (which is monitoring of the body's output: faeces, urine, saliva, nasal secretions, etc) and direct external monitoring will be able to detect pretty much any isotopes if they have been taken into the body and not already passed through or decayed. There are some more invasive monitoring techniques like lung lavage which are rarely used. Good estimates of body burden can be made. These techniques have been used not only in routine nuclear/rad work & accident/research purposes but for nuclear medicine procedures too so they are well established.

 

[|Fred]

thx artax :)
here is the link to the full res http://cryptome.org/eyeball/daiichi-npp/daiichi-photos.zip

 

[TCups]

thx artax :)
here is the link to the full res http://cryptome.org/eyeball/daiichi-npp/daiichi-photos.zip

VISIBLE MAJOR STRUCTURAL DAMAGES AFTER EARTHQUAKE BUT BEFORE EXPLOSIONS?

@Fred:
included in your photo summary files, ... 12.jpg

The south face of Bldg 1 has a huge diagonal crack. That looks a lot more like possible damage from the lateral thrust forces of a 9.0 quake than an explosion, IMO.

Addendum CORRECTION:

Bloop! There is wasn't. The "What?" that I wasn't seeing before -- shadows from the stairs.

March 12, March 18 images confirm the crack at the base of the south face of Bldg 2. Look closely at the south face of Bldg 4 before the explosion!

Image source for last two images: DigitalGlobe.com

 

[artax]

thx artax :)
here is the link to the full res http://cryptome.org/eyeball/daiichi-npp/daiichi-photos.zip

Cheers Fred, they're great!

 

[Joe Neubarth]

The sea water samples with highest radiation levels are taken 330 metres south - the yellow line is 330 metres according to google.

They need to take their samples out on the end of that rock and cement Quaywall extending to the right in the photo..

Looking at the swell action you can see the waves coming in at the bottom of the photo. That usually equates to water coming in from the ocean at that point. The absence of swells right at the plant effluent area suggests water flowing out to sea (path of least resistance. I'm an avid body surfer and know how to look for rip currents.) I am willing to bet that their strongest radioactive contamination will be along that quaywall

 

[timeasterday]

VISIBLE MAJOR STRUCTURAL DAMAGES AFTER EARTHQUAKE BUT BEFORE EXPLOSIONS?

@Fred:
included in your photo summary files, ... 12.jpg

The south face of Bldg 1 has a huge diagonal crack. That looks a lot more like possible damage from the lateral thrust forces of a 9.0 quake than an explosion, IMO.

Addendum:

Bang! There it is! The "What?" that I wasn't seeing before.

March 12, March 18 images confirm the crack at the base of the south face of Bldg 2. Look closely at the south face of Bldg 4 before the explosion!

Image source for last two images: DigitalGlobe.com

That looks more like a pipe or some other manmade structure. It's a straight diagonal line with what may be a shadow that makes it look a little deeper.

EDIT: upon closer inspection all I see is a stairway.

 

[artax]

VISIBLE MAJOR STRUCTURAL DAMAGES AFTER EARTHQUAKE BUT BEFORE EXPLOSIONS?

@Fred:
included in your photo summary files, ... 12.jpg

The south face of Bldg 1 has a huge diagonal crack. That looks a lot more like possible damage from the lateral thrust forces of a 9.0 quake than an explosion, IMO.

Addendum:

Bang! There it is! The "What?" that I wasn't seeing before.

March 12, March 18 images confirm the crack at the base of the south face of Bldg 2. Look closely at the south face of Bldg 4 before the explosion!

Image source for last two images: DigitalGlobe.com

I think your diagonal crack is where the stairs were ... look at building 2 in your first image there.

still examining these fascinating images!

 

[timeasterday]

I think any theories of the cap being blown off reactor 3 can be put to bed now. You can clearly see the steel girder framework largely intact over most of the building. If you look closely at photo "aerial-2011-3-30-0-50-20.jpg" you can see the greenish color of the SFP (at least I think that's it).

 

[artax]

I think any theories of the cap being blown off reactor 3 can be put to bed now. You can clearly see the steel girder framework largely intact over most of the building. If you look closely at photo "aerial-2011-3-30-0-50-20.jpg" you can see the greenish color of the SFP (at least I think that's it).

We could really do with a plan veiw of where the reactor is in relation to the cube. Yes if it's in the centre then I aggree but where you can see the green of possibly the crane... which is what I thought it was, there's an obvious hole been blown through everything. possibly the SFP being so heavily built. strong and deep it directed the hydrogen explosion in an upwards direction, piercing like a shaped charge and sending a bit of the roof up.?