Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[AtomicWombat]

Promecheng - Thanks for the good answer - taking the BBC figures, the rate of decay is extremely fast in the beginning and then it slows down - I assume because it is the sum of several exponentials. Given that it is .5% at the end of Day 1, I therefore assume it will still be a significant number at Day 6; using your numbers and a guess I suppose we can't count on a decline of significant heat production for quite a few days yet?

This image from the UCS site shows the cooling rate settles to a simple exponential after about 1 day:

Here is the accompanying text:
"Figure 2 shows the typical rate at which heat from a shut-down reactor core boils away water when the cooling systems are not functioning. The vertical axis shows the boil-off rate in gallons per minute. The horizontal axis shows the time, in days, since the reactor was shut down. Even a week after being shut down, the heat from a reactor core boils water at a rate of nearly 60 gallons per minute. The boil-off rate declines with time while the rate of radioactive release decreases.

The reactor core resides in the lower portion of the reactor pressure vessel (see Figure 3). The normal water level inside the reactor vessel is roughly 196 inches, or 16 feet, above the top of the reactor core. The nuclear fuel is protected against damage caused by overheating as long as it remains covered with water. A rough rule of thumb is that it takes 200 gallons of water to raise or lower the level inside the reactor pressure vessel by 1 inch.

For the boil-off rate of 60 gallons per minute a week after shut down, it takes around 200 seconds for the water level inside the reactor pressure vessel to drop an inch. If the reactor cooling system fails one week after the reactor was shut down with the water level inside the reactor vessel is at its normal level, it would take approximately 11 hours for boil-off to reduce the water level down to the top of the reactor core."

Source:
http://allthingsnuclear.org/post/3859682324/reactor-core-cooling"

 

[AtomicWombat]

Vanadium melts at 2183K
The fuel is cladded and encased in neutron absorbing substances.

Even if we assumed that they had a 50cm cubic block of material ...

Back of the envelope calcs:
50cm cubic block of spent fuel, 40 days old

LaMarsh, pg 415 suggests a rough exponential relationship for the power ratio in fuel over infinite cooldown time: y = 1.0023E-02exp(-2.3049E-07*x) y is power ratio, x is seconds
...


0.5 emissivity (pulled out of ***)

reactor operating at 50W/cm^3 initially, 0.225 W/cm^3 in fuel after 40 days.

Equilibrium temp: 900K

That's hot, but I don't see how it is hot enough...

Firstly its Zirconium NOT Vanadium.

Unfortunately for now I'll have to match your BOTE calculation with my own BOTE calculation.

From:
http://allthingsnuclear.org/post/3859682324/reactor-core-cooling
Assume the fuel heat is equivalent to a boil-off rate of 50 gal/min (approx 10-20 days after removal from reactor).
This is equivalent to about 8 MW.
Using the stefan-Boltzman Law: Power = 5.67E−8*T^4, one square metre of Zironium will give off about 1.15 MW of heat (as a black body) at its melting T = 2128K. That requires about 8/1.15 say 6 m^2 of unobstructed radiation area to dissipate.

But we don't need to reach 2128K, we only need to reach 1500 K where zirconium reacts exothermically in air or steam. (Note zirconium is protected by a passivating layer that breaks down at this temperature.) The oxygen-Zr reaction gives off 12MJ/kg; the H2O-Zr reaction gives off 5.8MJ/kg.

One square meter of Zr at 1500K radiates 5.67E−8*(1500)^4 = 0.28 MW. 8/0.28 ~ 28 metres squared to get rid of 8MW. To maintain the spent fuel at this temp it would have to have an effective unobstructed radiation area to a black body receiver of 28 square metres. I don't know for sure how tightly the bundles are packed (what is the external area), but I doubt there is enough heat transfer. It is possible that convection could solve this but only after an explosion blowing a hole in the external wall and allowing enough air flow.

 

[TCups]

This image from the UCS site shows the cooling rate settles to a simple exponential after about 1 day:

Here is the accompanying text:
"Figure 2 shows the typical rate at which heat from a shut-down reactor core boils away water when the cooling systems are not functioning. The vertical axis shows the boil-off rate in gallons per minute. The horizontal axis shows the time, in days, since the reactor was shut down. Even a week after being shut down, the heat from a reactor core boils water at a rate of nearly 60 gallons per minute. The boil-off rate declines with time while the rate of radioactive release decreases.

The reactor core resides in the lower portion of the reactor pressure vessel (see Figure 3). The normal water level inside the reactor vessel is roughly 196 inches, or 16 feet, above the top of the reactor core. The nuclear fuel is protected against damage caused by overheating as long as it remains covered with water. A rough rule of thumb is that it takes 200 gallons of water to raise or lower the level inside the reactor pressure vessel by 1 inch.

For the boil-off rate of 60 gallons per minute a week after shut down, it takes around 200 seconds for the water level inside the reactor pressure vessel to drop an inch. If the reactor cooling system fails one week after the reactor was shut down with the water level inside the reactor vessel is at its normal level, it would take approximately 11 hours for boil-off to reduce the water level down to the top of the reactor core."

Source:
http://allthingsnuclear.org/post/3859682324/reactor-core-cooling"

Perhaps. But as a radiologist, I make my living with my eyes, interpreting what I see. Here is a picture from the net of the Fukushima (nomen, omen?) of units 3 and 4, dated October 3, 2008. Note the location of the berm (X).

another view, after unit 3 has exploded, but before the explosion and fire at unit 4:

http://media.kansas.com/smedia/2011/03/14/20/495Japan_Earthquake.sff.slideshow_main.prod_affiliate.80.jpg

Some brave soul peeked out from behind that berm (X) in the first photo to take this picture (annotated with my personal interpretations).

Presuming the access tunnel (1) in the diagram below is coming from the building next to the reactor in the first photo, which seems reasonable, that square hole in the side of unit 4 is, in fact, precisely where the diagram puts the SFP's location (3).

Do you think the roof of the Unit 4 building still looks intact? If there is still (boiling?) water in the SFP, where is the steam? Instead, I see a faint cloud of dark, sooty smoke wafting from the square hole with the red dots inside at an angle across the tower to the right, in the last photo. I hope I am wrong, but my eyes tell me something different from the official reports you quote.

 

[AtomicWombat]

Hi TCups

Perhaps. But as a radiologist, I make my living with my eyes, interpreting what I see.[/PLAIN]

Presuming the access tunnel (1) in the diagram below is coming from the building next to the reactor in the first photo, which seems reasonable, that square hole in the side of unit 4 is, in fact, precisely where the diagram puts the SFP's location.

Agree - I originally posted that picture asking if that was where the SFP is located. The best interpretation I can make is that the missing panel is where the SPF was located, although behind another wall deeper in the building. The hydrogen was sourced from the zirconium-steam reaction and was most concentrated above the SPF. Not surprisingly the building was breached next to the SFP during the subsequent explosion. I believe interpretation of this phoito is what underlies Gregory Jaczko's testimony to congress that "there was now little or no water in the pool storing spent nuclear fuel at the No. 4 reactor of the Fukushima Daiichi Nuclear Power Station, leaving fuel rods stored there exposed and bleeding radiation into the atmosphere."
http://www.nytimes.com/2011/03/17/world/asia/17nuclear.html?hp

I've put in a subsequent post where I suggest there is enough heat for the fuel assemblies to melt, particularly if there is not enough convection cooling.

Do you think the roof of the Unit 4 building still looks intact? If there is still (boiling?) water in the SFP, where is the steam? Instead, I see a faint cloud of dark, sooty smoke wafting from the square hole with the red dots inside at an angle across the tower to the right, in the last photo. I hope I am wrong, but my eyes tell me something different from the official reports you quote.

Whilst I don't believe anyone can be sure, the tongue of material coming out of the large hole has the appearance of a molten metal-slag mix. Once it started leaking from the building it was exposed to convective cooling which solidified the "crust". Was it you who first suggested this?

I'm less convinced about the red dots. However I am far more concerned about reactor 3 than the authorities. I suspect the steam cloud is coming from what remains of the reactor core. The explosion last Monday was directed strongly vertically suggesting to me it originated from deep within the containment structure. It clearly carried substantial solid material to a height of 400-500 metres. Whilst I can't be sure this may have been due to a melt-down of the fuel rods in reactor 3. They melted through the reactor floor (1500 Celsius) and fell into the flooded "dry-well" below. This triggered a large steam- zirconium-water-hydrogen explosion. I suspected this not only blew the concrete top off the containment, it also blew most of the reactor contents out of the reactor.

These are my best visual interpretations based on what I know of the reactor chemistry (I'm a former chemical engineer) and careful observations. In the absence of honesty from TEPCO and the Japanese government what else can you do?

 

[AtomicWombat]

Some brave soul peeked out from behind that berm (X) in the first photo to take this picture (annotated with my personal interpretations).

This appears to be a wide-angle picture taken from the same location at the same time. The photographer was even further than the berm:

 

[kfmfe04]

If the reactors are assumed to be lost, can some material be dumped on top of the entire site so that should explosions occur, the spread of radioactive contamination can be limited?

From my layman's viewpoint, it seems to me that officials are just reacting to what is happening rather just assuming the worst and doing what they can to limit a worst possible outcome, but maybe there are no better solutions? (I'm certainly not an expert in this area).

 

[Pythagorean]

I haven't read through all 20 pages here, but I'm hoping that b) is a unique question:

what are the chances of both a) and b) or a) an c) happening if:

a) a significant meltdown occurs
b) radiation taking the Kuro Siwo (an ocean current) to Alaska
c) significant levels making it to Alaska via atmospheric transport

I would think the ocean currents are much slower, more violently diffusive carriers and wouldn't effectively deliver radiation doses to Alaska's coast.

Would half-lives even be long enough for the journey in either case in post-meltdown?

 

[marwood]

Informative article on the activities to control the reactor accidents at the Japanese nuclear plants:

Below is a summary [for the general public] on the Fukushima situation prepared by Dr Josef Oehmen, a research scientist at MIT, in Boston.

He is a PhD Scientist, whose father has also extensive experience in Germany ’s nuclear industry.

~~~~~~~~~~~~~~~~~~
What happened at Fukushima
I will try to summarize the main facts. The earthquake that hit Japan was 7 times more powerful than the worst earthquake the nuclear power plant was built for (the Richter scale works logarithmically; the difference between the 8.2 that the plants were built for and the 8.9 that happened is 7 times, not 0.7). So the first hooray for Japanese engineering, everything held up...

Informative? or opinion piece? Dr. Josef Oehman is not trained nor an expert in nuclear plant operation or technology. His academic biography states:

''The main research interest of Dr. Josef Oehmen is risk management in the value chain, with a special focus on lean product development. Risk management allows companies to design and achieve the optimal risk-return balance in their portfolio of activities, successfully take entrepreneurial risks, increase their performance, and focus their attention on where it is needed most.

Josef is also involved in the cooperation project between the King Fahd University in Saudi Arabia and MIT, focusing on research in product development and risk management. He is a member of the supervisory board of Climate InterChange, a company developing and implementing projects for the reduction of carbon emission. Before joining LAI, he was the Director for Supply Chain Management at the ETH Center for Enterprise Sciences (BWI) at the Swiss Federal Institute of Technology (ETH Zurich).

He wrote his PhD thesis at the ETH Zurich on the topic of Supply Chain Risk Management with a focus on China. In his research, he investigated and optimized the integration and cooperation between Swiss companies and their Chinese suppliers.

Josef worked as Assistant to the CTO of SIG Holding AG and in parallel pursued an international MBA at the Collège des Ingénieurs in Paris. He was intensely involved in corporate-wide Technology and Innovation Management and was responsible for technology projects. He studied mechanical engineering at the Technical University of Munich, majoring in Product Development and Production Management. He wrote his diploma thesis at LAI on Risk Management in Product Development.''

http://lean.mit.edu/about/lai-structure/faculty-researchers-and-staff/oehmen-josef

 

[CAC1001]

Could this event be worse than Chernobyl, or is that scaremongering?

 

[AtomicWombat]

If the reactors are assumed to be lost, can some material be dumped on top of the entire site so that should explosions occur, the spread of radioactive contamination can be limited?

From my layman's viewpoint, it seems to me that officials are just reacting to what is happening rather just assuming the worst and doing what they can to limit a worst possible outcome, but maybe there are no better solutions? (I'm certainly not an expert in this area).

Agree kfmfe04,

There are obvious practical difficulties. The sheer magnitude of the clean-up task is incredible but unavoidable.

I haven't really thought through the best way to go about it, but I suspect that once the Japanese get their act together (& stop listening to TEPCO & start being honest with their own people), we will see a typically Japanese response. I expect that will involve large robotic Earth moving and construction machinery.

By way of example, Rio Tinto in Australia is already using Komatsu 930E trucks with autonomous control (290 tonne capacity) for iron ore mining - these are controlled remotely from Perth (>1000 km away). They also have other autonomous equipment, such as drills and trains.
http://www.womp-int.com/story/2010vol01/story026.htm"

This will take months to do and the difficulties are enormous - not least being the need to harden such vehicles against radiation. It will be incredibly expensive.

Disclaimer: I have no association with Rio Tinto or Komatsu.

 

[Borek]

Could this event be worse than Chernobyl, or is that scaremongering?

While the situation is serious, so far there is no reasons to believe radioactive contamination of similar scale is possible. Situation is dynamic, so it may change, but as of now such comparisons are scaremongering, I have no doubts about it.

 

[Borek]

the need to harden such vehicles against radiation

That will be a serious problem, high levels of ionizing radiation render electronics useless. From what I remember they were trying to use some early robots in Chernobyl, at least to send cameras for a situation assessment, it didn't work as planned.

 

[AtomicWombat]

Could this event be worse than Chernobyl, or is that scaremongering?

Yes it is quite possible in my view.

There are obvious differences. The most notable is that the Chernobyl reactor used a graphite moderator. Once the initial explosion exposed the graphite to the outside air it burned (for many days) and lofted radioactive material into the air. It would be hard to find a more efficient method of spreading radioactive material from a damaged reactor. It is quite unlikely (in my view) that the radiation at Fukushima will spread as rapidly as in Chernobyl.

On the other side of the ledger. Four reactors have potentially been breached and much more nuclear material is exposed in the spent fuel rods. (I can find no reference to spent fuel rods at Chernobyl - can someone help?) So, it would appear much more nuclear material is involved. Also in this region the population density is much higher than near Chernobyl. The world's largest city is only 250 km away. In time the wind and rain will spread the radiation and create a huge area of contamination.

I dearly hope this is not the outcome.

 

[mattm2]

I am scientifically impaired; however, I have the following questions:

1. Was there no one thinking ahead in this crisis in that: someone had to know that exposing the spent fuel rods to air was not good; and, that the SFP water was increasing in temperature. I believe hot water evaporates faster than cold water. At any rate, it should be easy to calculate/estimate (based on surface area, ambient air temperature/humidity, and temp. of water) how fast the SFP water would evaporate. Additionally, before radiation got real bad: they could have been sending someone to check on the number 4 SFP water level. If the water level started to get low: run a 2 or 3 inch hose(s) to the tank and add sea water to it. It sounds like there were not enough people putting their minds on the problem and not enough workers to carry out the proper tasks. Now the radiation is too high to run a hose to the number four tank. I guess it is easy to be an after-the-fact armchair critic.

2. How many gallons of water do the SFPs hold? If they are quite large; then, I do not think that a bambi bucket helicopter drop would do much good. 7.5 metric tons of water is only about 2000 gallons--and most of that missed.

3. Given the present situation, what are all the ways to get water into the Spent Fuel Pools (SFPs) besides having a volunteer suicide mission?

 

[dave2004]

Here is some information about the spent fuel stored in TEPCO facilities:
http://www.zerohedge.com/sites/default/files/Containment%20Pools.pdf
Maybe this helps you to make a better guess at what is going on right now.

 

[TCups]

This appears to be a wide-angle picture taken from the same location at the same time. The photographer was even further than the berm:

That puts the source of the photo in better perspective. But my assessment wasn't too far off. Another ominous observation -- look carefully at the wind direction. Those smoke plumes are drifting inland, not out to sea.

 

[Borek]

look carefully at the wind direction. Those smoke plumes are drifting inland, not out to sea.

Doesn't mean much - can be local (vortex in a given place, wind blowing in different directions at different heights), can be just temporary (few seconds of wind that twists in every direction, but blows one way on average).

 

[TCups]

Hi TCups
. . .

Whilst I don't believe anyone can be sure, the tongue of material coming out of the large hole has the appearance of a molten metal-slag mix. Once it started leaking from the building it was exposed to convective cooling which solidified the "crust". Was it you who first suggested this?

In this thread, perhaps. I haven't seen or read any other comments about that "tongue", but it caught my eye for sure.

I'm less convinced about the red dots. However I am far more concerned about reactor 3 than the authorities. I suspect the steam cloud is coming from what remains of the reactor core. The explosion last Monday was directed strongly vertically suggesting to me it originated from deep within the containment structure. It clearly carried substantial solid material to a height of 400-500 metres. Whilst I can't be sure this may have been due to a melt-down of the fuel rods in reactor 3. They melted through the reactor floor (1500 Celsius) and fell into the flooded "dry-well" below. This triggered a large steam- zirconium-water-hydrogen explosion. I suspected this not only blew the concrete top off the containment, it also blew most of the reactor contents out of the reactor.

These are my best visual interpretations based on what I know of the reactor chemistry (I'm a former chemical engineer) and careful observations. In the absence of honesty from TEPCO and the Japanese government what else can you do?

I can't be sure if the hole is at the bottom leel of the SFP, or perhaps, the floor level just below the bottom level of the pool (ie, perhaps hot slag went down, into a pump room, then out the wall). Either way, a big hole in that location is very bad, as is the wind shift.

 

[mattm2]

Off topic; however, related to the multi-faceted Japanese crisis: The Hedge Funds are involved in Economic Terrorism again (like they have been several times in the past few years--including speculating in oil recently and driving up the price). Basis for my allegation is that they are buying massive amounts of Yen for the sole purpose of profiting speculative Yen buying. This in turn increases the value of the Yen (macro economics would indicate that the value of the Yen should be decreasing as a result of the disaster if there were no outside interference). By increasing the value of the Yen, it makes Japan's exports more expensive and thereby exacerbates the negative economic results of the disaster.

 

[lapsedgeo]

The amount and quality of information you guys have amassed and what you have in your brain boxes is amazing for an non-scientific outsider to behold, keep up the good work. Can I ask a probably annoying basic question (in relation to everything else on here), watching the helicopters dropping water rather ineffectually by the looks of it, as it is spraying and blowing in the wind is it becoming contaminated to any extent on the way down and being spread about, albeit in a very limited localised way (hopefully)?

 

[AntonL]

Could this event be worse than Chernobyl, or is that scaremongering?

While the situation is serious, so far there is no reasons to believe radioactive contamination of similar scale is possible. Situation is dynamic, so it may change, but as of now such comparisons are scaremongering, I have no doubts about it.

Experts in Germany reckon by Saturday the accident could be of similar or larger proportion if reactor 4 and 3 SFP run dry and the fuel starts burning. Radiation at the facility will be so high that it is not approachable.

So far every effort seems to fail to get water sprayed or dropped into the SFP.

The first attempt by SDF helicopters looked more like a sprinkling of Holy Water, I truly hope that the Japs are not hoping for Divine intervention and that we see some real workable results by tomorrow.

 

[kfmfe04]

Off topic; however, related to the multi-faceted Japanese crisis: The Hedge Funds are involved in Economic Terrorism again (like they have been several times in the past few years--including speculating in oil recently and driving up the price). Basis for my allegation is that they are buying massive amounts of Yen for the sole purpose of profiting speculative Yen buying. This in turn increases the value of the Yen (macro economics would indicate that the value of the Yen should be decreasing as a result of the disaster if there were no outside interference). By increasing the value of the Yen, it makes Japan's exports more expensive and thereby exacerbates the negative economic results of the disaster.

Actually, speculators are buying JPY because they are using the Kobe Earthquake as an indication of what will happen next. In that case, there was repatriation of foreign (non-JPY) currencies (sell foreign currency, buy JPY) to invest in reconstruction, so hedge funds are stepping ahead of this expected repatriation. OTOH, people believe that with the disaster in place, foreign banks will no longer object to BoJ intervention to weaken the yen. They may have already intervened or are definitely ready to intervene if necessary.

 

[Astronuc]

In this thread, perhaps. I haven't seen or read any other comments about that "tongue", but it caught my eye for sure.

The debris hanging from the base of the hole in Unit 4's secondary containment looks like insulation. The red parts look like they are painted red - not glowing red.

The hole appears to be above the floor of the concrete structure of the reactor building.

The flow of plumes at that level will be directed by local currents. The plants sit east of a hill. The atmosphere above generally blows from west to east, but the jet stream can kink, blowing anyway from N to S, and perhaps westward (or SW or NW), but it predominantly moves from W to E at that latitude ~ 32 N.

I'll comment later once I digest the news/reports.

Given 4 units in various states of distress - and three with mature cores (meaning fuel with one, two or three cycles of operation + a portion of the current cycle) - and with the ruptures in containment - I can appreciate the comparison to Chernobyl. From the outside, it looks pretty bad.

 

[AntonL]

Off topic; however, related to the multi-faceted Japanese crisis: The Hedge Funds are involved in Economic Terrorism again (like they have been several times in the past few years--including speculating in oil recently and driving up the price). Basis for my allegation is that they are buying massive amounts of Yen for the sole purpose of profiting speculative Yen buying. This in turn increases the value of the Yen (macro economics would indicate that the value of the Yen should be decreasing as a result of the disaster if there were no outside interference). By increasing the value of the Yen, it makes Japan's exports more expensive and thereby exacerbates the negative economic results of the disaster.

Actually, speculators are buying JPY because they are using the Kobe Earthquake as an indication of what will happen next. In that case, there was repatriation of foreign (non-JPY) currencies (sell foreign currency, buy JPY) to invest in reconstruction, so hedge funds are stepping ahead of this expected repatriation. OTOH, people believe that with the disaster in place, foreign banks will no longer object to BoJ intervention to weaken the yen. They may have already intervened or are definitely ready to intervene if necessary.

I read somewhere that Japanese insurance companies will have to raise the money for their payouts in non Yen currencies - hence a huge demand for Yen will be created - hence the strong Yen

I certainly would not talk of economic terrorism - just market forces at play.

 

[mattm2]

kfmfe04: The process of repatriation by itself would strengthen the Yen; however, BOJ has stated that there has been little repatriation by insurance companies, etc. because they have sufficient liquidity without selling US assets. In other words, the strenthening of the Yen has been caused by speculation. I hope that the hedge funds get burned bad by a massive multi-national effort to weaken the Yen. Would serve them right.

 

[kfmfe04]

NHK just reported an earthquake Chiba, Ibaraki, Saitama, Tokyo, and Kanagawa. Looks like a 4 on the Japanese scale in Chiba, 3's in Tokyo - M5.8, but no chance of tsunami. Centered off Chiba. Around 9:21:32PM Japanese time.

Looks like still plenty of aftershocks.

 

[AntonL]

has anyone seen the photos that the USA made by their remote controlled drone or UAV type Global Hawk stationed in Guam. NHK reports that the USA government has made photos available to Japanese government of todays flights.

This puts weight onto the following CNN report
On Wednesday, Gregory Jaczko, the head of the U.S. Nuclear Regulatory Commission told Congress that spent fuel rods in the No. 4 reactor had been exposed because there "is no water in the spent fuel pool," resulting in the emission of "extremely high" levels of radiation.
But Japanese authorities disputed Jaczko's assertion, citing information gathered from a helicopter flight over the plant.

 

[AntonL]

NHK just reported an earthquake Chiba, Ibaraki, Saitama, Tokyo, and Kanagawa. Looks like a 4 on the Japanese scale in Chiba, 3's in Tokyo - M5.8, but no chance of tsunami. Centered off Chiba. Around 9:21:32PM Japanese time.

Looks like still plenty of aftershocks.

528 aftershocks of magnitude greater than 4 since the MR9 event

You can count them http://earthquake.usgs.gov/earthquakes/recenteqsww/Maps/10/140_40_eqs.php"

 

[kfmfe04]

528 aftershocks of magnitude greater than 4 since the MR9 event

You can count them http://earthquake.usgs.gov/earthquakes/recenteqsww/Maps/10/140_40_eqs.php"

Nice link. TY.

Another M5.8 off Fukushima at 21:55PM. I don't know how anyone in Japan can get any sleep - if it's a really big one, you wouldn't have enough time to wake up and compose yourself enough to attempt an escape. With so many aftershocks, how could you distinguish the difference until it's too late?

 

[TCups]

I keep looking at images. It is hard to know for sure, but I believe this is probably unit 4

and it looks like the access tunnel to the crane lift may in fact be in the back of the building. In retrospect, that probably makes more sense as the fuel rod assemblies would need to come in on a truck. If that is the case, the my orientation of the diagram is bass-ackwards.

I find Astronuc's interpretation of a sheet of insulation hanging out the hole hard to refute, and I certainly agree the red dots are not clearly something "hot". Also, on reflection, I suspect that had a pile of hot nuclear material slagged out the side of the building, there would be a lot more residual heat and smoke.

All reasons for a little optimism for a change. Let's hope that the SFP is intact and that they can get more water to it somehow.

Does anyone have any "hard" information about the power plant and reactor layouts? Is the road behind the reactor building and the covered tunnel leading in from the back of the building where the fuel rod assemblies would arrive at the plant, or would it be more likely to be accessed from the building in front of the power plant for some reason?