Fukushima: What's the worst that could happen? Nuclear experts explain.

"The probability of this occurring is hard to calculate primarily because of the possibility of what are called common-cause accidents, where the loss of offsite power and of onsite power are caused by the same thing. In this case, it was the earthquake and tsunami. So we're in uncharted territory, we're in a land where probability says we shouldn't be. And we're hoping that all of the barriers to release of radioactivity will not fail."

—Physicist Ken Bergeron, who has performed research on nuclear reactor accident simulation at Sandia National Laboratory in New Mexico, in Scientific American.

(image: on-air explanation of the current status of reactors at Fukushima plants 1 and 2, on NHK TV Japan, via Joi)

Boing Boing editor/partner and tech culture journalist Xeni Jardin hosts and produces Boing Boing's in-flight TV channel on Virgin America airlines (#10 on the dial), and writes about living with breast cancer. Diagnosed in 2011. @xeni on Twitter. email: xeni@boingboing.net.

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a_user

#
1152: France is recommending that its citizens leave the Tokyo region, citing a risk of further quakes and uncertainty over nuclear plants, Reuters reports.

BBC live

time stamp 10 mins ago Japan time
a_user

3. Point Nuclear

Two scenarios are currently possible:

* A supervised plants defective, in which case the risk is that of residual contamination associated with controlled release of radioactive gases, with a negligible risk for the city of Tokyo. This scenario is currently favored by the Japanese authorities and by many scientists.

* Or rather the explosion of a reactor with release of a radioactive plume. This plume can be in Tokyo within a few hours, depending on the direction and wind speed. The risk is that of contamination.

The critical period is three to four days to come.

Due to the shutdown of part of nuclear power, power cuts are announced, such as the late afternoon.

4. Recommendations:

The Japanese Meteorological Agency is to report the probability of another earthquake force 7 located in the northern Kanto. This probability is 70% within three days and 50% within days.

Given the foregoing (the risk of a major earthquake and uncertainty over the nuclear issue), it seems reasonable to advise those who do not have a specific reason to stay on the Tokyo region of s it away from the Kanto region for a few days.

more (french)

from the French Embassy website in Tokyo
awjtawjt

unfortunately, the situation is continuing to crescendo, rather than diminish.
Chaoskitten

Wow, it’s almost as though investing heavily in a powerful but immature technology in which glaring problems remain unsolved while discounting the inherent unpredictability of circumstances is incredibly dangerous. I sure am glad all the untreatable radioactive waste these plants produce is locked away under the ground where it’ll be safe from unforseen events like this one.
noen

Sowing calm in the face of a focused campaign of FUD from professional anti-nuclear activists

“My anger continues at the efforts to take advantage of the tragedy by professional anti-nuclear activists with long standing agendas to inhibit the development of the only form of reliable power that has the potential to break modern society’s damaging addiction to hydrocarbons. It is incredible to me that there are people in the world who believe that the most important thing on the agenda of Japanese government officials at the present time is a continuous stream of updates regarding the events that are unfolding at a few nuclear power plants that are having some difficulty providing post shutdown cooling.”

Good blog.
daen

@a_user, @tp1024: Are you willing to disengage your unwarranted enthusiasm and withdraw your unsupported statements about containment vessel integrity two months on, with Fukushima now upgraded to Level 7, the evacuation zone extended, thousands of tonnes of contaminated water discharged into the Pacific, a meltdown some 16 hours after the earthquake now evident, and still no end in sight to the chaos and misery?
a_user

@ Chaoskitten and when the radioactive plume blows over my house your words will being me comfort.
capl

German news is saying that the recent addition of a mixture of both plutonium and uranium raises the risk of contamination seriously. This mixture was added a few months ago to reactor 3 and the radiotoxicity of plutonium is “enormous”, raising the risk of human contamination far above a uranium letdown alone.
http://www.spiegel.de/wissenschaft/technik/0,1518,750668,00.html
a_user

#
1353: A state of emergency has been declared at a second nuclear power plant in Japan, the International Atomic Energy Agency has said. “Japanese authorities have informed the IAEA that the first, or lowest, state of emergency at the Onagawa nuclear power plant has been reported by Tohoku Electric Power Company,” a statement said, according to the AFP news agency. The alert was declared “as a consequence of radioactivity readings exceeding allowed levels in the area surrounding the plant”. “Japanese authorities are investigating the source of radiation,” it added.

#
1309: Japan’s Tokyo Electric Power Co (tepco) is preparing to put sea water into the No 2 reactor at Fukushima Daiichi, or Fukushima 1, power station, Reuters reports. It has already been pouring water into reactors No 1 and 3 to try to cool them.

#
1304: A reminder that Japan’s nuclear safety agency rates the incident at level 4 on a scale of 1-7. The accident at Three Mile Island was 5, Chernobyl was 7.
BBC live

last time tag 5 minutes ago Japan time
awjtawjt

I read bunch of these sources. The real danger isn’t that the cores will melt through the containment vessels and get out. That could happen only if there were no cooling water or cooling mechanism …*at all.* That’s not going to happen, yet, because a lot of other things will happen before it.

The danger is that the cooling circulation mechanism becomes damaged from a hydrogen explosion in the building, rendering the circulation pumps damaged and therefore useless. This would make the reactor vessel un-chillable, and then overpressurized, and the dome gets blown off of both the reactor and the concrete containment chamber. Then we will have another Chernobyl with direct, uncontrolled exposure of fissile materials to the atmosphere.

That’s what they’re not telling you. They’re not telling you WHY a disabled cooling system is bad and what could result from it being non-functional. They are not telling you what could happen next if the reactor vessel and its contents aren’t cooled sufficiently. They are not telling you what a partial meltdown of the core means, and how they can stop those uncontrolled reactions. They are not telling you what they are doing with the newly contaminated sea water, or precisely how the cesium got out of the building yesterday and already irradiated dozens of people.

What they will not tell you is that they are desperately trying to stop a runaway train, and so far, they have not and cannot.

What they will continue to tell you, until after the fact and it’s too late to run away, is that only safe levels of radiation have been released and that the situation is under control.

It most certainly is not under any control whatsoever, at this point, and those who express confidence have their heads buried in a pile of boron.
Anonymous

At least they didn’t get Michael Bay to give his opinion on what the worst-case scenario is – http://xkcd.com/748/
a_user

#
1353: A state of emergency has been declared at a second nuclear power plant in Japan, the International Atomic Energy Agency has said. “Japanese authorities have informed the IAEA that the first, or lowest, state of emergency at the Onagawa nuclear power plant has been reported by Tohoku Electric Power Company,” a statement said, according to the AFP news agency. The alert was declared “as a consequence of radioactivity readings exceeding allowed levels in the area surrounding the plant”. “Japanese authorities are investigating the source of radiation,” it added.

BBC live

time stamp 30 mins ago approx
JayByrd

In addition to the six reactors at Fukushima, they also store decades worth of spent fuel there in facilities that do not have containment. That also has to be cooled and maintained.
moniker

I didn’t find the Scientific American article to be particularly helpful. One article that was linked in the discussion gives a much clearer explanation:
http://bravenewclimate.com/2011/03/13/fukushima-simple-explanation/

This author believes that the risks are fairly low now. The control rods + the boric acid that has been pumped in will have completely shutdown the nuclear reaction. All that is left is removing some residual heat which should have mostly been done by the seawater. His analysis may be slightly optimistic but it does seem to me that there is a lot of FUD out there about the risks of this plant and this article does seem to be pretty well informed.
a_user

@awjtawjt
People are doing fine job in panicking themselves.
Panic emails, in spam quantities, were already circulating about the fallout from the burning petrochemicals on Friday, followed by “run to the airport” emails circulating amongst the foreign community yesterday, to the empty petrol pumps and food hoarding today.

The logistics of getting anywhere is daunting.

The government are also not spelling things out because they don’t want to cause an economic meltdown.

What I’m not clear on is which is their top priority.

As to what they’re not telling in people in terms of joining up dots. I’m no expert but here’s what I’ve learned:

From the moment that they opted to vent the reactor 1, it was clear they were having problems. Doubly so when they opted to use sea water as that would make the reactor unable to be restarted at a later time. The heat in the reactor is coming from waste in the fuel rods which account for 10% of the heat produced when the reactor is active. The explosion on reactor 1 was caused by hydrogen, itself caused by the water reacting with air on the exposed core sheathes, coming from the core itself means it carried caesium and iodine with it, hence why they were distributing iodine tablets in the adjacent area to stop the internal absorption of iodine which would lead to radiation sickness.

It is still rated behind Three Mile Island.
- awjtawjt
  
  “It is still rated behind Three Mile Island.”
  
  For now…
Anonymous

The main issue is that they have to deal with several overheating reactors at two sites. As soon as just one of these goes up Tschernobyl-style there will be so much radiation in the area that you cannot keep up the emergency measures on the remaining reactors.
a_user

#
1541: A former nuclear power plant designer has said Japan is facing an extremely grave crisis and called on the government to release more information, which he said was being suppressed. Masashi Goto told a news conference in Tokyo that one of the reactors at the Fukushima-Daiichi plant was “highly unstable”, and that if there was a meltdown the “consequences would be tremendous”. He said such an event might be very likely indeed. So far, the government has said a meltdown would not lead to a sizeable leak of radioactive materials.

BBC live

time stamp 19 minutes ago Japan time

@awjtawjt I sincerely hope you have the luxury of simply taking part in a discussion. I don’t. My priorities for arguments about fossil fuels vs atomic energy, Japanese flags in the shape of anything or points of order are lower than the decision whether or not to move myself and my family from the house where we have food, water and heat to escape nuclear fall out. And has been since Friday.
a_user

#
1600: At the same time, Malcolm Crick, the secretary of the UN Scientific Committee on the Effects of Atomic Radiation, has told the Reuters news agency: “This is not a serious public health issue at the moment. It won’t be anything like Chernobyl. There the reactor was operating at full power when it exploded and it had no containment.”

#
1558: He (Mr Goto) described the worst-case scenario: “It is difficult to say, but that would be a core meltdown. If the rods fall and mix with water, the result would be an explosion of solid material like a volcano spreading radioactive material. Steam or a hydrogen explosion caused by the mix would spread radioactive waste more than 50km. Also, this would be multiplied. There are many reactors in the area so there would be many Chernobyls.”

BBC live
- tp1024
  
  I don’t care about who Malcom Crick is, or what his credentials are: He is dead wrong.
  
  Just read the wikipedia entry on Tscherobyl if you don’t take my word.
  
  Tschernobyl was operating in a precarious state at about 200MW of power but it was dampened by Xenon-135. This meant, the power was 200MW, but almost all control rods were *out* of the reactor (something that people were instructed not to do, even if Stalin (or whoever) himself ordered it – apparently that wasn’t thought to apply to a lowly military commander….), which put it into a configuration that could produce about 20.000 MW of power (alomst ten times of rated power), if the Xenon were gone.
  
  Curiously enough, the design of the reactor meant that cooling water was getting especially hot at that kind of power level and started to boil. When the Xenon was suddenly running out (no room to explain, but it did so quickly), power jumped to 20GW and the almost boiling water just flashed to steam and completely destroyed the comparatively feeble reactor vessel (it was a huge cylindrical vessel, both its size and shape make it *much* more vulnerable to the pressure of the steam) and of course, there was nothing beyond that.
  
  At this point, all the radioactive goodness of the reactor was out and about. (It didn’t help that a nuclear excursion followed the destruction of the reactor vessel about 3 seconds later, along with an explosion equivalent to about 10 tons of TNT.)
  
  Oh yeah right, *after* that, the remains of the core that weren’t distributed by almost 2000 tons of graphite burning in the open air, started to melt. The molten core of Tschernobyl is in the remains of the reactor building to this day. It’s all the other stuff that got out, which is the problem.
  
  –
  
  In Fukushima, the reactors were scrammed right away and the reactor vessels are still structurally intact, the containment too (the fact that pressure is building up inside of the containments, proves that it is still perfectly sealed).
  
  When a core starts to melt in this situation, this is really bad news for anyone hoping to use the reactor again (they won’t) and it means lots of expensive work in decommissioning. But it is no threat to the public.
  
  Yes it cannot be ruled out that the reactor vessel may be damaged. However, this is not going to happen so long as there is cooling water, and I’m not sure if this scenario applies at this time at all. Because most calculations focussed on an immediate loss of all cooling and subsequent meltdown after about three hours – not a meltdown after three days.
  
  Here is an example of a study, there are lots:
  
  http://www.osti.gov/bridge/servlets/purl/6124656-R8y05j/6124656.pdf
  
  Just google for “lower head failure” or better: “lower head failure bwr”
  - MooseDesign
    
    Two things:
    
    1. My understanding is that Chernobyl had no interior metal/concrete containment vessel by design. A design considered by western standards at the time to be unjustifiably dangerous. When the exterior wall and cap was gone radiation was free to escape unhindered (except eventually when concrete was poured over the top). Its a completely different design from the Fukushima reactors which have both the interior lightbulb container as well as the exterior concrete containment. So I’m not sure what counter point you were making with the history lesson but whether you accept Malcolm Crick’s credentials or not, even if the containment does fail at Fukushima it is, by definition, going to be different. In fact it appears that you reinforce exactly what Crick says: a) Chernobyl was running at full power (and beyond), b) he says that there is not a serious public health risk “at the moment”. It is qualified and is also true. c) there was no containment. In the context of knowledge of the design of the reactor at Chernobyl, this is also true. d) He says that it won’t be the same as Chernobyl. For all the reasons above, this is demonstrably true.
    
    2. Just as a matter of clarity, the question of cost and decommissioning is pretty much moot as the reactors in question were scheduled for decommissioning later this year. Not a pretty decommissioning ceremony by any means, and will likely be a great deal more expensive and dirty, but they were slated for shut down this year.
    
    Anyway, here’s the thing: if your goal is indeed not to rile this guy up, why then are you taking issue with what is an outside, dispassionate, balanced, cautious statement that things are unlikely to be as bad as Chernobyl and on the other end of the spectrum take to task Mr. Goto (a nuclear plant designer… I guess his credentials aren’t good enough either) who was answering a theoretical question (if you read the actual statement) as to worst case scenarios? Your methods are blindingly contradictory as well as misleading in context of each another.
    
    “It’s to point out that the Japanese spokespeople you keep quoting are doing so after the fact and minimizing the situation.” The fact that a_user has only actually directly quoted one Japanese official and one former plant designer (the rest were international atomic energy officials, new organizations and embassy officials from France) really throws into question whether you are reading or skimming what is being posted and whether, despite your claims to the contrary, anything that is said, positive or negative, could possibly placate you.
    
    No one is saying its all roses. It isn’t. But honestly, “Many other people in the news have lamented how they know the government is trying to keep people calm…”? Is this a joke? You even have a beef with this? The sensationalist media on the one hand and a cautious government information campaign on the other. “In the absence of real-time straight-talk”… what are your requirements to satisfy that definition? My brother in Tokyo says that they are having press releases literally every few minutes and press conferences regularly (at least every hour). The city wide PA system is broadcasting announcements and updates for travel advisories and emergency best practices. Seriously. What more are you really expecting?
    
    You are by all appearances hellbent on staking out a contrarian position that seems impossible to satisfy, or you went to the Kent Brockman school of jouralism. You want trustworthy sources but dismiss the opinion of a nuclear plant designer and secretary of the UN Scientific Committee on the Effects of Atomic Radiation. You want realtime updates but then nitpick sound bytes as being horribly flawed and inaccurate. I mean, in one sentence, “It’s to point out that the Japanese spokespeople you keep quoting are doing so after the fact and minimizing the situation” you even manage to lay into them for the sins of both not reporting on something until after it has happened and not somehow having populated the preceding statements with conjecture about every outcome within the foreseeable future. Get real. You say you don’t want to cause panic but your every statement appears to be designed to do exactly that. I’m just glad you aren’t in charge of emergency broadcasts or public relations.
- tp1024
  
  Oh, and as to the statement of Mr. Goto, it is not much better.
  
  As mentioned in the study I linked to, there will be no sudden release of a large hot mass of molten core (“corium”) – because there are holes in the bottom part of the reactor vessel with instruments stuck in them. Those instruments would melt first and release a stream of corium, rather than one large blob.
  
  And again, this is for scenario without any cooling at all and an immediate meltdown (with corium that is still producing much more heat), not a one delayed by several days.
  
  Similar calculations apply for breach of the containment vessel. But even a broken containment vessel would release corium into a large underground torus filled with water.
  
  All of this is incomparable to a reactor with an open lid, spewing its content out in a massive explosion – as in Tschernobyl.
  
  And that is for Mark I containment build in the late 1960ies. There have been improvements (addressing, among many other issues, the problem of venting hydrogen without risking an explosion …)
awjtawjt

Neither of you are understanding me. Or course all reporting is after the fact. It’s the minimization and obfuscation that are the problem. Downplaying the crisis while the crisis mounts. It’s MIS-information, and it’s EVIL.

If, one moment, the word is that the reactor is under control and being cooled by multiple redundant systems, and the next report is that there was an explosion and a “small non-significant release of radiation”, and the NEXT report is that 6 miles are being evacuated, and the next is that 12 miles are being evacuated and 160 people are being tested for significant radiation exposure, oh and NOW we are pumping seawater into the reactor, oh and NOW two more reactors are having trouble… oh and NOW… ???

Yeah, THAT’S the kind of level-headed, keep-everyone-calm kind of reporting we’ve all come to know and love.

How’s that overconfidence working out for ya?
- a_user
  
  #
  2042: Professor Patrick Regan, radiation and environmental protection expert from Surrey University, has told the BBC that it appears none of the secure vessels holding radioactive material at the reactors in Japan has broken, and “it looks like the worst is over”.
  
  BBC live
  
  you really need to learn about reading news bylines.
  - awjtawjt
    
    Let’s hope… but… We’ll see…
    
    I would never sacrifice my skepticism to anyone’s expert status. Neither should you.
DaG68

@anon #1: It’s not saying that an earthquake and a tsunami are not connected; it’s saying that in general having such a powerful event that makes *both* off-site and on-site power (which are, of themselves, unrelated) fail is very rare.
- Anonymous
  
  “It’s not saying that an earthquake and a tsunami are not connected; it’s saying that in general having such a powerful event that makes *both* off-site and on-site power (which are, of themselves, unrelated) fail is very rare.”
  
  I’m not saying that anyone thinks they’re unconnected. Or that these large events aren’t “very rare”.
  
  I’m saying that a “common cause” accident was probable for any large enough earthquake. This was highly predictable. Do you disagree?
  
  This:
  
  “the loss of offsite power and of onsite power are caused by the same thing. In this case, it was the earthquake and tsunami. So we’re in uncharted territory, we’re in a land where probability says we shouldn’t be.”
  
  Is absurd.
  
  For a large enough earthquake and tsunami this is exactly where probability says we should be. This statement makes it appear as if we are dealing with unforeseen circumstances. It seems far less likely that a large quake would NOT produce “common cause” accidents.
  - a_user
    
    The quake epicentre was correctly predicted – what wasn’t factored in was the slippage along the plate edge, creating an energy source of 500km in length.
    The energy produced created waves that, combined with the local topography, could easily breach the existing sea defences. In other words the Japanese had prepared for the event but not the size.
    
    Given that the last time this happened was in the 9th century there, and only that was understood by examining sediment deposits, it’s fair to say this couldn’t have been predicted.
    
    I also feel it’s important to stress, all the death and carnage was caused by the tsunami not the quake.
    - dragonnurse1
      
      Actually the last time a tsunami took out this much of Japan was in January 1700. The subduction zone on our Pacific Coast (from northern end of Ca up to Canada) released sending a tsunami to Japan.
      
      One of the worst case scenario is if the cores overheat and melt through the bottom of their containment building and contact the ground water. Think “China Syndrome”.
  - DaG68
    
    “I’m not saying that anyone thinks [earthquake and tsunami a]re unconnected. Or that these large events aren’t “very rare”.
    
    I’m saying that a “common cause” accident was probable for any large enough earthquake. This was highly predictable. Do you disagree?”
    
    I see your point now. I do not know what the expert quoted meant (and even less am I an expert myself). I may guess he meant that an event of such a magnitude is extremely uncommon, while most other disrupting events (normal blackouts, extreme weather conditions, system failures, you name it) should not affect both power sources at once.
- a_user
  
  The problem was the area of the source of the tsunami, while the local authorities had correctly predicted the source, they didn’t forsee the distance the movement would spread along the edge of the tectonic plate, and thus the tsunami was much much larger and breached existing tsunami barriers.
  
  Hence the power plants were actually taken out by the tsunami killing the generators that ran the main cooling systems and the back ups ones.
  
  To be fair the only other time something similar had happened was in the 9th century and they only know about that from analysis of coastal deposits.
dragonnurse1

People are panicky. With all the problems the Japanese are facing the government does not want anymore hysteria therefore any information disseminated will be designed to downplay potential hazards. I find it amusing that so many “experts” are saying the worst is over when there have been more than 80 “aftershocks” rated 6.0 or greater in the last 24 hours and some scientists are predicting another 7.0 quake as likely to occur in the next 48 – 72 hours.
tp1024

a) The point I was making is that saying that Tschernobyl “was running at full power” isn’t even wrong. It’s a meaningless statement.

It’s like burning petrol inside of the boiler of a steam engine and saying it was running on full power when it burst. The way in which the Tschernobyl reactor was being operated at the time of the accident, had nothing whatsoever to do with any semblance of regular operation. Just that fact that the reactor was able to skip from 200MW to 20GW (or so) in a matter of seconds should make that very clear.

It is neither remotely comparable to a perfectly shut down reactor (as in Fukushima or Three Mile Island) nor to a reactor running in any regular kind of way. You just don’t start up and try to run a reactor with any significant amount of Xenon-135 inside of it any more than you would burn petrol in the boiler of a steam engine.

b) Mr. Gotos statement was not a statement relevant to the power plant in question. In case you missed it, I was citing a study concerned with the exact same kind of power plant to proof that point. Plus, there are several more studies out there, that reinforce it.

Mr. Gotos suggestion, that a steam explosion strong enough to destroy both reactor and containment could be initiated by the molten core falling into the water, has been discredited as unrealistic by a number of studies looking into the matter for *this particular type of reactor*. He is right, however, that this mechanism is the focus of attention when it comes to worst-case scenarios for all types of light water reactor *in general*. This makes it a true statement *in general*, but a wrong statement *in the particular case*.

Especially since all worst case scenarios are concerned with an immediate, unmitigated, meltdown after a nearly complete loss of coolant. Again, very far from what was known to have happened even a few hours after the earthquake.

I didn’t mean to discredit Mr. Gotos credentials in general, it is just that he obviously wasn’t up to date with his knowledge in this particular case.
a_user

there have been several magnitude 6 aftershocks and at least 1 magnitude 7 since Friday, what I believe they’re worried about is the chance of an after shock of 8 magnitude sometime between now and Thursday.
Anonymous

A tsunami following an earthquake? This seems entirely probable. Am I missing something?
Tony

Reminds me of the United 232 plane crash in Sioux City, Iowa. The tail engine exploded and shrapnel took out all three hydraulic systems leaving the pilots with no control of the wing surfaces. Aircraft control and engineers on the ground had no training or manual to help the pilots because it was assumed the chance of losing all three hydraulic systems was so small as to be impossible.
fishyswaz

Graph translation
red tag 1: melting (hard to read)
red tag 2: outbuilding explosion

Green line is electrical systems, blue is cooling, orange is the nuclear container.

First reactor: X(failed), added sea water, added sea water
Second reactor: X(failed), Triangle(partial failure), under high pressure
Third reactor: X(failed), failed(water being added), under high pressure
reactors 4-6 were already stopped for inpections
a_user

@tp1024 thanks for that link
Anonymous

Please keep the info coming BB, your coverage/info is to me the most up to date, relevant, helpful and sadly worrying, but greatly appreciated.
a_user

live from NHK –

Chief Cabinet Secretary Yukio Edano is giving a press conference core number 3 is partially deformed (ie melting)

http://www3.nhk.or.jp/nhkworld/r/movie/
a_user

The same spokesman also said there is a build up of hydrogen like reactor 1 which exploded earlier.

What they’re not saying is the implication that the worst case would be a breach in the containment area, designed to hold the melted reactor. What isn’t clear is if the speckled boxes are the outer side of the containment cell – ie as happened with reactor 1 the hydrogen blows the roof off will that heave the deforming reactor exposed.
- MooseDesign
  
  This may help illustrate the layout and what blew away during the explosion: http://www.world-nuclear-news.org/uploadedImages/wnn/Images/bwr%20cutaway.jpg
  
  My understanding (INANE) is that they are still a ways away from a true collapse of the core and that a collapse is indeed what would happen if they lost control of the reaction. Rather than exploding upward and out of the container, the core would melt and drop down to the area at the bottom of the torus. From there, the melting would eventually penetrate the container underneath the reactor.
  - a_user
    
    ahh that makes things clearer – the framework exposed by the explosion at reactor 1 is not part of the concrete cladding.
    
    Also I checked, Three Mile Island was at 5 INES, so I’m guessing the 1 difference is the amount of melting.
    
    Still worried though :/
a_user

#
0650: Despite that risk of a second explosion, the government spokesman says reactor No 3 could withstand a blast in the same way that reactor No 1 did.

here

Again the paucity of terms leaves me asking if by reactor, they mean the metal shell around the core or the shell and containment area.

I hope it’s the second.
a_user

TEPCO has just issued a statement placing Fukoshima at 4 on INES (The International Nuclear and Radiological Event Scale which goes from 1-7), to put that in perspective Chernobyl was rated 7.
MooseDesign

Phenomenal NY Times animation and illustration of the reactor’s design and issues at hand: http://www.nytimes.com/interactive/2011/03/12/world/asia/the-explosion-at-the-japanese-reactor.html

Great way to visualize it for those trying to wrap your heads around it.

(sorry, tried to post this on the submitterator and it wouldn’t let me)
awjtawjt

@a-user, the point is not to rile you up. It’s to point out that the Japanese spokespeople you keep quoting are doing so after the fact and minimizing the situation. Noticeably. At each escalation, there was no hint of that possibility in the immediately previous announcement. It appears to be like “1984″ where a government official hands the spokesman a slip of paper mid-speech to instantly reverse what he just said. Because the original plan was only to obfuscate and placate, not to actually inform.

Nor am I saying that it should be outright panic.

Many other people in the news have lamented how they know the government is trying to keep people calm, but they feel placated and that they aren’t being given straight information. They say that they would panic less if they trusted that they were getting real-time straight-talk. It’s your call how you feel about that.

In the absence of real-time straight-talk, it might be worth people’s consideration to retreat to safer ground further away, rather than risk being told too late there’s a major accident underway. Which would be too late. But if you trust your sources of information and trust their timing, then that is your personal choice.
- a_user
  
  You seem to be making the assumption that I accept whatever I’m told without thinking critically. This annoys for the reason I stated in my previous post.
DaG68

@a_user #30: I am not sure why you are saying what you are saying in reply to my message, but thanks nonetheless.
- a_user
  
  ahh yes it looks like I misread your post.
futnuh

Here’s a considered blog post written by someone with good technical chops: http://atomicinsights.blogspot.com/2011/03/nuclear-plant-issues-in-japan-are-least.html