Dramatic escalation in Japan (Fukushima Nuke Plant)

http://www.world-nuclear-news.org/RS_Possible_damage_at_Fukushima_Daiichi_2_1503111.html

by Element_ • 15 years ago

133 210 15 years ago

Radiation has been measured at a rate of 400 mili sieverts near reactor 3. 100 mili sieverts is enough to make a male infertile.

Previous measurements were in micro sieverts.

Source: https://twitter.com/#!/timeouttokyo/status/47480888463859712

burke• 15 years ago

Just as an added data point, one of the earliest measurements released (just before or after the first explosion) was 1015 µSv.

pessimist4• 15 years ago

Turns out the optimistic reports upvoted by hacker news were polyannish. There appear to be 2 borderline catastrophes right now -

1. In reactor 4 spent fuel rods are burning and radioactivity is being freely vented in to the air. NONE of the optimistic reports suggested this possibility but I see a prophetic article at http://www.nytimes.com/2011/03/15/world/asia/15fuel.html.

2. Reactor 2 has had an explosion that has damaged the core containment structure - something we were assured would not happen.

Why were engineers so optimistic, while the ground reality is so much worse? Probably the complexity of the system escapes us and look at small parts of the issue and assume they are under control. In reality many things are interacting and the combination can overwhelm defences. For eg. as water is being routed to reactors 1, 2 and 3 to prevent meltdowns, the spent fuel rods are overheating.

Hubris strikes again.

gnosis16• 15 years ago

"Turns out the optimistic reports upvoted by hacker news were polyannish."

There are way too many people on here who've been drinking too much of the radioactive koolaid doled out by the nuclear industry.

The general consensus here tends to be that nuclear power is wonderful and amazingly safe.

Well, we're seeing them being proven wrong yet again. How much more proof are they going to need? How many more nuclear disasters is it going to take?

pyre4• 15 years ago

I generally see people talking about how safe the new reactor designs are, and how it's a tragedy that people are so afraid of nuclear that they won't let them be built. The reactors in Japan are 40-year-old designs. You can't compare them on the same level. It's like saying that people in favor of nuclear power claim that Chernobyl never happened because 'safe nuclear' == 'never was a reactor that was unsafe ever built.'

sorbus• 15 years ago

How many major nuclear disasters have there been in the last, say, 50 years? Three mile island and Chernobyl are the two big ones that everyone knows about, and considering that people are saying that this is the third largest [EDIT: actually the second largest, at this point], I take that as an endorsement of nuclear power. As compared with coal, oil, natural gas, and so forth, which function by spewing pollutants into the environment continuously, during normal operation.

Yes, I would be thrilled if we switched entirely to solar, wind, geothermal, and hydroelectric power sources, but nuclear power isn't anywhere near as disastrous as the people strongly against it would like us to believe. It's also not as safe as a lot of people would like to think, but, by and large, it is fairly safe.

mistermann5• 15 years ago

> how many more nuclear disasters is it going to take?

Indeed....please provide us with the list of nuclear disasters, it should be an easy exercise judging by the tone of confidence in your post. Just for fun, throw in some stats on deaths per kwh of electrcity.

PREDICTION: you will not respond to this, because there have been no nuclear disasters. And no one disputes that in practice, nuclear is the safest form of power statistically. If you want to assert that nuclear power is incredibly powerful and dangerous, that is one thing, but trying to pass off potential disaster as reality, is a but disingenuous.

ANH2• 15 years ago

Historically, coal-fired power plants have been much more dangerous for humans than nuclear power plants. I think the record shows that nuclear power is on the whole pretty safe.

Regarding proof: I don't think anything has been proven, yet, except that there have been a lot of powerful forces at work with this disaster.

redthrowaway3• 15 years ago

>Well, we're seeing them being proven wrong yet again. How much more proof are they going to need? How many more nuclear disasters is it going to take?

You've had one and a half. TMI had no ill effects on health, Chernobyl was caused by Soviet incompetence, and Fukushima is the result of an earthquake 7 times more powerful than it was designed to survive. Compare that to the damage caused by oil spills alone.

No power source that is economically viable on a large scale is 100% safe, including nuclear. They do their damndest, but sometimes it fails. There were some design flaws in Fukushima, namely the placement of the backup generators and the height of the tsunami barriers, but the precipitating earthquake was still the strongest in 1200 years. It looks like the containment vessel on the #4 reactor has been breached, and that's very, very bad. Still, the only people injured were those injured by the hydrogen explosions, not by radiation. There's been a few people (~12) who suffered radiation exposure, I believe all plant workers.

Is this event bad? Yes. Could it be another Chernobyl? Probably not. Reactor 4 is on fire, and is releasing radiation into the atmosphere, but on nowhere near the scale that Chernobyl did.

Most of the "optimism" yesterday was based on what had actually occurred: the coolant had failed, #1 was flooded, and #3 had encountered the same problems. Both reactors had hydrogen explosions outside of the containment vessel that didn't compromise them. No significant radiation had been released.

Today is a different story. We'll keep an eye on things and see how they progress, but the optimism was based on the situation at #1 and #3, not the yet-to-happen situation at #2 and #4.

redwood• 15 years ago

Well put. This is a highly chaotic situation unfolding as we speak. If any of that fuel catches fire, those of us sitting on our couches in silicon valley may very get a nice early spring gift from jet stream.

Even if AT THIS POINT the chances of such a fire are <1% (which quite frankly seems optimistic) we should be very very concerned...

Software engineers especially, but engineers in general, have a tendency to love complex machines. But engineers of all kinds SHOULD know best: that there are ALWAYS bugs, and where you least expect them.

We ought to put aside the politics here: whether you like nuclear power or you don't: we've all been very much dependent on it, and benefited from it greatly. It's impact on life is different, but not clearly better or worse than other sources.

Let's hope the engineers on the ground in Japan are getting very very creative.

timerickson5• 15 years ago

"those of us sitting on our couches in silicon valley may very get a nice early spring gift from jet stream."

This brings up a question I've been wanting to ask since the ordeal started. How much do we know about the severity of radioactivity being spread to Hawaii, California or countries outside of Japan?

Assuming worst case scenarios, are the citizens of Hawaii in real danger of poisoning? Should neighboring countries be stocking up on potassium iodine?

chc2• 15 years ago

Alternative explanation: Being a pessimist is not productive. Woo-hoo, you were something in the ballpark of right. Is the world better because of it? If you look at every situation and assume the worst, you'll be right sometimes, but you'll never accomplish anything.

Aetius2• 15 years ago

Only the paranoid survive.

waterlesscloud2• 15 years ago

The wise man knows when pessimism is warranted.

gamble2• 15 years ago

I prefer my nuclear engineers to pay attention to the worst-case scenario, even if it does make them a wet blanket at parties.

rbanffy2• 15 years ago

However, nuclear power generation is serious. Things happen very fast and can turn nasty in milliseconds if you don't pay attention, if you don't understand what is happening, if you don't know what you are doing and if you don't have the right tools at hand to deal with whatever is going on.

One thing I learned in school is that you respect any machine bigger than you.

I have no idea why things went so completely wrong there. I always assumed people who design and build nuclear reactors do so in ways they can't fail. Now I am more inclined to believe they are happy to have plans B through G instead of having a really bulletproof plan A. It's certainly more impressive to list a long series of failsafe devices than just having a very unimpressive core that can cool itself in the event of an emergency.

It appears they were much less respectful than they should have been. Some people may end up paying with their lives.

btucker• 15 years ago

I think a big part of it is we've had it drilled into us that fears of nuclear meltdowns are irrational. That people are just misinformed & scared of something they can't see or possibly understand. And we like to think we're smarter than the general population.

But clearly no one knows how bad this situation is going to get.

hartror• 15 years ago

1. The building on 4 is on fire, not the spent fuel rods.

2. The hydrogen explosion on 2 may have damaged containment.

pessimist4• 15 years ago

Well, at least one of the 2 possibilities is closer to the worst case since radioactivity levels are 500x (400 mill-sievert, from 800 u-sievert) what they were a few hours ago.

_delirium• 15 years ago

I have no way of knowing if their report is accurate, but this is what the NYT says on #1 (http://www.nytimes.com/2011/03/16/world/asia/16nuclear.html):

That fourth reactor had been turned off and was under refurbishment for months before the earthquake and tsunami hit the plant on Friday. But the plant contains spent fuel rods that were removed from the reactor, and experts guessed that the pool containing those rods had run dry, allowing the rods to overheat and catch fire.

gamble2• 15 years ago

Yes, the upbeat reaction to Fukushima outside Japan has been disturbing. The fact that it would be hard to equal Chernobyl doesn't diminish the reality that this is easily the second-worst disaster in the history of nuclear power. People have been killed, and the entire complex is effectively trashed. One reactor at TMI took 14 years and a billion dollars to clean up; Fukushima is going to be a nightmare to set right even if things don't get worse.

Of course, this is assuming that things aren't worse than the official statements let on. The sordid history of the Japanese nuclear industry, including falsification of safety records at Fukushima, doesn't inspire confidence. Japanese nuclear officials are notoriously slippery in front of the press, and the lack of reliable information from Fukushima has been very frustrating. No one really knows what's going on there, and every time the officials claim to have it under control another building explodes.

timerickson5• 15 years ago

Some context for the ongoing cost of Chernobyl:

In Ukraine, Chernobyl related benefits and programs are still funded by 5-7 percentage of government spending each year. In Belarus, government spending on Chernobyl reached 22.3 percent of the national budget in 1991, declining gradually to 6.1 percent in 2002. Total spending by Belarus on Chernobyl from 1991 through 2003 was more than US $13 billion. (Chernobyl Forum, 2006)

sp3325• 15 years ago

This is a longish, very specific (but apparently also overoptimistic) description of the mechanics of the reactor problems. http://theenergycollective.com/barrybrook/53461/fukushima-nu...

pessimist4• 15 years ago

To update, NHK is reporting the fire at reactor 4 is out.

jedsmith8• 15 years ago

The information coming out of Japan right now is very piecemeal and very incomplete. We are also depending on an organization without a stellar reputation when it comes to telling the truth[1], and a culture programmed to downplay very bad things. It has really pained me to see people rush to believe that everything is fine.

Conclusions at any stage of this crisis have been premature, but HN seems to want a heavy dose of finality to a crisis that isn't even over yet. Apparently people don't want it to be a big deal, but it's slowly turning into a big deal. It just is. Instead of big essays and conclusions about how the powers-that-be have it under control complete with inaccurate depictions of how a reactor works, why don't we focus on facts?

With that in mind, we do not know how bad it is. Anyone who says they do is lying to you. It isn't over, and it is a basic fact of logic that we will not be able to reflect on how bad this is or was until it is over.

At the risk of a neener-neener I told you so, I presented some of this viewpoint[2] on the self-aggrandizing risk management Ph.D.'s everything's fine piece, but my viewpoint was drowned out by people wanting to rush to a conclusion so they can put the crisis out of sight and out of mind.

[1] http://edition.cnn.com/2003/WORLD/asiapcf/east/06/17/tokyo.s...

[2] http://news.ycombinator.com/item?id=2319305

forensic7• 15 years ago

Whether you like it or not, the beliefs of most intellectual engineer types is that the nuclear power plant dangers have been solved.

It's inconceivable (cue sound clip from Princess Bride) to most of us that extremely extensive and effective contingency plans are not in place.

The nuclear risk is obvious, and so any nuclear construction's main emphasis must be on handling all possible contingencies... right?

If Fukushima does end up being a "Big Deal" that is going to forcibly shift the world view of many many engineers and hackers. It will represent a piece of data that is fundamentally at odds with our view of the world.

The facts will eventually win out, but for the short term, it is necessary that we go through these cycles of disbelief and then shock. Because that's just reality.

I will be shocked if Fukushima causes serious harm to humans because until now it has been inconceivable to me that people making nuke plants could possibly underestimate the risks. If my inaccurate beliefs are shattered by the harsh reality of nuclear related deaths then... that's just how it will have to be. I'll have to eat my hat. I'm not looking forward to it.

In the meantime I have to go with what I know. Which is that this should not be an issue that threatens human life.

jshen2• 15 years ago

" It will represent a piece of data is fundamentally at odds with our view of the world."

Sadly that rarely changes anyones mind.

gnosis16• 15 years ago

"Whether you like it or not, the beliefs of most intellectual engineer types is that the nuclear power plant dangers have been solved."

That reminds me of all the bragging about how the Titanic was "virtually unsinkable".

Alex3917• 15 years ago

"Whether you like it or not, the beliefs of most intellectual engineer types is that the nuclear power plant dangers have been solved."

This belief is basically it's own logical fallacy; the idea that because someone has figured out a theoretical solution to a problem, the issue is moot. I feel like I've posted this previously, but I can't find now so maybe not.

Tycho2• 15 years ago

Is it even possible to handle all contingencies though? I don't know enough to do the maths, but when you've got

    four different reactors

    an earthquake

    followed by a tsunami

    followed by loss of electricity for the emergency pumps

    followed by parts of the plant blowing up

    followed by tons of dust getting in the way

    followed by possibly more aftershocks

    followed by possibly more tsunamis

    followed by possible injuries to the personnel needed to run these operations

    considering other equipment can break down

    considering political pressures to make certain decisions

    considering some of the physics/chemistry here may be entirely novel

    ...

Think of all the different permutations in those variables, just how many scenarios have been prepared for? It has to be more complicated than just 'if casing 1 fails, casing 2 will stop it, and if casing 2 fails, casing 3 is there'

harisenbon2• 15 years ago

Not trying to be contrary, just sharing what I have heard.

I don't know what you consider 'Serious Harm to Humans', but as of Sunday, there were an assumed 160 people with radiation exposure (9 confirmed).[0]

From what I remember on the news the other day, the reason for the failures of the plants was the fact that they had not conceived of an earthquake and tsunami of this magnitude. PM Kan said that there were adequate protections in place for the facilities, but the earthquake was beyond the conceived scope of the protection.

Also, while 20km from site 1 have been evacuated, they've needed to extend the radiation-affected area to 30km. Unfortunately, it's too wide of an area to evacuate, so they have told people to stay in their homes.

[0]http://jp.reuters.com/article/mostViewedNews/idJPJAPAN-19971...

edited: edited "poisoning" into "exposure" edited: Added evacuation distances

juiceandjuice3• 15 years ago

It's never been 'inconceivable' that nuclear plants would fail. Nuclear energy was a risk nations were willing to take to keep you plugged in, making this post right now. You're faulting engineering that predates the microprocessor, at a power plant scheduled to be decommissioned soon, for failing in the two worst natural disasters (earthquake + tsunami) in Japan's modern history.

I just wanted to make that clear.

richcollins• 15 years ago

The occurrence of radiation related deaths in this one instance isn't strong evidence that it is more dangerous than alternatives:

http://www.scientificamerican.com/article.cfm?id=coal-ash-is...

cdavid2• 15 years ago

Who are most intellectual engineers ? I agree that most news seem to be conflicting, and very hard to understand for the layman, but I cannot possibly see how anyone can claim the issue has been solved when even the people with incentive to downplay the reality (Japanese gvt, TEPCO) say that the situation is increasingly worrying.

When you read nuclear news website (http://www.world-nuclear-news.org/), it seems the issue is potentially very serious, where the potentially become less and less uncertain rapidly. Given that this news website has the support of the world nuclear association, I would be inclined to trust them most than any general news channel out there (being tv/journals or of course Japanese gvt).

Gupie• 15 years ago

"until now it has been inconceivable to me that people making nuke plants could possibly underestimate the risks"

What I don't understand is why the walls meant to protect the plant from a Tsunami were too low.

brazzy3• 15 years ago

the beliefs of most intellectual engineer types is that the nuclear power plant dangers have been solved.

Not at all true for the intellectual engineer types I know. You may want to reassess how much of your certainties are cultural.

it has been inconceivable to me that people making nuke plants could possibly underestimate the risks.

That sounds so inconceivably naive to me that, out of the context of the rest of your post, I'd be sure it was meant sarcastically.

icarus_drowning2• 15 years ago

While it is true that there are many people attempting to call the crisis "over" without adequate evidence that this is the case, I think it is equally obvious that there are many people who are doing the opposite: namely, attempting to make the case that the crisis is far worse than the incomplete facts indicate.

I applaud your more measured approach, but I must say that, as someone who has read most of the stories and comments regarding this topic that have hit the front page, I do feel that you are decidedly in the minority. There are plenty of people rushing to call this a horrendous disaster, who are privy to the same limited information, and who are likewise doing very little to contribute to the discussion.

jedsmith8• 15 years ago

I mostly agree, but we have to assume the absolute worst and be rewarded with good news, rather than assume everything's fine and be surprised when a large number of Japanese citizens get thyroid cancer. Even though I think "oh my God, Chernobyl!" is uncalled for at this point, the fact is that the limited information doesn't change that we might be in a horrendous disaster (and arguably are).

The information we do have tells us it's bad; the information we don't have doesn't tell us how bad.

mechanical_fish• 15 years ago

why don't we focus on facts?

Because we don't have any actionable ones?

But, okay, as you wish. I have the crisis firmly in mind now. I will not "rush to believe that everything is fine" or anything.

So.

Do you have any advice about what action I should take next? I live twelve time zones away, am a citizen of a different country, and have only a passing acquaintance with nuclear engineering.

I can't accomplish anything useful by panicking. I can't change building codes from N years ago, I couldn't prosecute anyone in Japan for negligence even if I had any evidence of same (which I do not), I can't dictate to Japanese industry even if I knew what to do (which I obviously don't), I can't run the Japanese government, I can't even vote in Japan. Neither I nor anything else we know can stop radioactive elements from decaying, and I can't unwind time and stop the earthquake.

I suppose I can raise my blood pressure, and raise the blood pressure of everyone else I know, and we might even achieve mass hysteria. Is that really a good idea? Why? Like every citizen of the USA, I happen to have some experience with mass hysteria. It didn't turn out well in 2001. I'm not anxious to see more of it.

What would you like me to do, instead of waiting for events to unfold, staying away from certain portions of the Japanese coast, hoping that various Japanese nuclear engineers have done their duty well, and meanwhile focusing on other things?

jedsmith8• 15 years ago

Why do you have to act? What impetus is making you do something, whether it be conclude about the crisis so you can put it out of mind or fly over and pump seawater yourself or something? What is preventing you from doing absolutely nothing and still not forming a conclusion?

This is the meat of the entire thing, I think, and those upvoting you are feeling the same way, so let's have a Robin Williams/Matt Damon moment, okay?

    YOU CAN'T DO ANYTHING. RELAX AND WAIT.
    YOU CAN'T DO ANYTHING. RELAX AND WAIT.
    YOU CAN'T DO ANYTHING. RELAX AND WAIT.

This incessant urge to do something is making you draw conclusions early, too, and I worry that you're having a hard time seeing an alternate approach: do nothing, relax, go about your life, and wait for the big word on what's going on.

This isn't your fault, either. It's the media's, for setting an expectation of knowing about something before it's over and for moving on before the long-term ramifications are widely disseminated.

fluidcruft• 15 years ago

If you're looking for something to do, beat the rush and go to Walgreens and buy iodine tablets.

tres• 15 years ago

I'm not sure whether it's that "HN seems to want a heavy dose of finality..." or if we're just naturally inclined to want good news in the face of overwhelmingly bad news.

I keep on thinking of Akira Kurosawa's "Dreams..." (One of the segments deals with just this kind of scenario. The protagonist finds himself in hell after a nuclear disaster.) A horror like this has been in the cultural subconscious of Japan for decades. They always knew that there was a possibility of something like this, but they chose to gamble against it happening.

They didn't do it because they were foolish, or naive. They did their best to avert that disaster. The people had faith in the talent and skills of those engineers responsible.

It's our nature to want to see the good... even in a horror like this. (Especially a bunch of people who are willing to risk everything to start a business.)

pyre4• 15 years ago

  > Apparently people don't want it to be a big deal, but it's
  > slowly turning into a big deal.

I think that people's reactions here are because they view this as the new beachhead in the 'nuclear is evil and will destroy the world' argument.

I think that the reality probably boils down to:

  It's possible to do nuclear in a safe way. It's even possible
  for humans to build such a system (i.e. the complexity
  is not out-of-reach), but it's possible that (like economics)
  this fails to take into account how illogical humans are (e.g.
  cutting corners on something that is *really* dangerous).

guelo• 15 years ago

I think a lot of the nuclear defensiveness attitude has to do with anti-leftist conspiracy bias. There are a lot of people that think that there are giant conspiracies run by environmentalists/hippies/peaceniks etc. that are blocking human progress, such as our ability to create nuclear power utopias. Forming your worldview around these types of ideologies can be uncomfortable when it clashes with reality.

gommm• 15 years ago

I don't see that as a giant conspiracy, I'm just convinced that most people do not have the knowledge necessary to have a useful opinion, don't think much, are easily swayed when people make them scared and running a political campaign using fear to galvanize the population into support is very effective.

So no, it's not a giant conspiracy, it's just normal human fear of the unknown...

chailatte• 15 years ago

Japan's warning that all people within 30 kilometers from Fukushima should stay indoors and that the radioactive winds may reach Tokyo in as little as 8 hours

Nikkei Flash Crash - Futures Plummet 16%

http://www.zerohedge.com/article/nikkei-flash-crash-futures-...

wbhart3• 15 years ago

As near as I can make out the details:

From the Japanese Prime Minister and Chief Cabinet Secretary. My source is NHK World (Japan News):

People up to 30km from Dai-ichi (number-1) plant are being asked to remain indoors. ALL people within 20km of PLANT 1 are being asked to evacuate.

The Japanese Govt. have asked the Japanese people to act calmly. (My comment: Watch the stock market now.)

Here we go (information for PLANT 1 - Dai-ichi):

Number 4 reactor: is on fire. There has been a hydrogen explosion there. There was an implosion of the building structure. Radiation is being released into the environment. Note reactor 4 was not in operation, but the fire has caused spent fuel to heat up generating hydrogen.

Number 2 reactor: there was a blast 30 minutes after number 4's explosion. A hole/crack (trans?) has been observed in the reactor. Radioactive material has been released to the environment.

At 10:22am between reactor 2 and 3, 30milliSievert and at reactor 4, 100 milliSievert. At reactor 3 the reading was 400 MILLI Sieverts. Note MILLI, not micro.

They believe the fire at reactor number 4 is likely the main cause of the dramatic increase in radiation.

The roof of a containment facility for spent fuel has also been damaged. It is possible that a leak exists there too.

pyre4• 15 years ago

  >  A hole has been observed in the reactor. Radioactive
  > material has been released to the environment.

I was just watching the press conference, and I could have sworn they said that the hole was in the reactor housing, and that little to no radiation was being released from this reactor. I was only paying half-attention though.

wbhart3• 15 years ago

I agree that the information was highly confusing. I also thought I heard this, but what I wrote is I believe correct nonetheless. :-(

The english translation is very poor. Yesterday they used the phrase: "there is a small chance of a massive release of radioactive material". The correct translation was in fact, "there is little chance that there has been any substantial release of radioactive material"

ashbrahma• 15 years ago

Didn't we just have a top story on HN yesterday which talked about how everything was safe?

http://news.ycombinator.com/item?id=2318980

gnosis16• 15 years ago

"Something that has not gotten much mention yet are the pools of high-level radioactive waste at these very same reactors, which also need cooling...

...if the fuel pools are not cooled, they will melt down, in which case we’re going to have Chernobyl on steroids."

http://www.democracynow.org/2011/3/14/japan_facing_biggest_c...

jfoley2• 15 years ago

A live geiger counter that is set up in Western Tokyo. That upward tail is pretty troubling. http://park18.wakwak.com/~weather/geiger_index.html

ronnier2• 15 years ago

Site is slow and not all graphs are loading, here's a SS I took of it with both this years and last years graph:

http://imgur.com/L8WKW?full

pero• 15 years ago

The top graph is now nosediving. An hour ago the upward-trend doubled in a 10 minute span.

What is the bottom graph representing?

ronnier2• 15 years ago

Here's the English dubbed LIVE NHK news from Japan:

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

dmm3• 15 years ago

Something I don't understand:

I keep hearing about seawater being pumped into the reactor chamber but apparently the chamber is still very hot. Where is all this seawater going? Steam? How big is this chamber?

EDIT: Also I've heard of at least two explosions. Does this mean that containment vessels are compromised? What exactly exploded?

wbhart3• 15 years ago

Whilst I can't claim to know the answer to your question, my guess/understanding is that it goes around the circuit and condenses in the heat exchange. It is then recycled.

Some steam is lost when they vent hydrogen, presumably.

dmm3• 15 years ago

Regarding the explosions, according to http://mitnse.com/, the Fukushima explosion occured in the ventilation system, outside of all containment vessels.

ErrantX4• 15 years ago

The water heats up, building pressure, and then they vent some steam to try and lower the pressure (and then, obviously, have to re-add water). The explosions happen because the steam separates into Hydrogen & Oxygen due to a reaction, and once outside that is an explosive mix.

The chamber is pretty large, several meters deep around the core.

The explosions are as a result of the release of the hydrogen/oxygen mix - which does not take much to catch - but they occurred outside the pressure vessel. Such a situations is technically planned for, the building structure "fails outward" allowing the blast out and away from the pressure containment. It is relatively unlikely to damage the integrity of the vessel in such a situation; they are very very strong pieces of kit (at three mile island the explosion took place inside the vessel and I believe it did not compromise its integrity).

At this stage is somewhat unclear but it appears that the third explosion has damaged one of the pressure vessels. However the technical explanations I am seeing are stating that it hasn't compromised the integrity of the containment; instead it appears to be saying that parts of the mechanism inside the containment are damaged (in this case the "torus" which is used as an emergency pressure relief system).

This is actually, though, a significant problem, if true, because it could affect what happens if it finally does meltdown (as I mention in another comment, my working knowledge of this form of reactor is incomplete, but IIRC the torus also forms part of the final emergency response to a meltdown).

Bottom line is; at this stage we know there have been 3 hydrogen explosions at 3 of the units, and one fire at another of the reactors. But it is still unclear the level of damage and risk with each unit - TEPCO (and indeed Japanese companies in general) tend to play down or not discuss details and risk publicly. Take this fire; no one really picked it up until it was out - at which point TEPCO appear to have started mentioning it.

If I had to lay a claim I suspect that reactor 2 at this stage will probably meltdown; loss of the torus is significant enough that it raises the risk of what they are currently doing (i.e. trying to cool the core).

dmfdmf• 15 years ago

I'll step in and defend nuclear power. This crisis looks horrible and might even lead to multiple core melts with containment breach. But let's not forget this was a horrible natural disaster first. We engineers never said a meltdown could never happen but that we have done everything possible to minimize the risk. I can predict that the amount of lives lost and property damaged due to this accident will pale when compared to other forms of energy including coal, gas or oil when things go wrong -- a price we pay every single day and is so common it hardly registers as news. What was cost of the BP oil spill? Read your local news for local gas explosions, oil spills, injured workers, etc. People are killed in the coal industry every single year. These are such every day occurrences they don't even register unless many people are killed or it involves barrels of oil. This accident is like a plane crash that draws attention to the horrors of flight when things go wrong -- but we still fly and flying is orders of magnitude safer then getting in your car.

All energy sources have risks and I believe that nuclear can be safe and reliable and better than any of the alternatives. In the end we will build nuclear power plants because there is no other large scale source of energy that can power an industrial civilization. (If you think so-called green energy and solar power can save us you need to learn some math. You are an environmentalist dupe). Need I remind all the ambitious hackers on HN that computers and the internet do not run on pixie dust -- it is running on oil, gas, coal and, yes, nuclear power right now. We know that at some point the oil will run out or become too expensive to mine. At that point its nuclear or turn off the lights and the drastic drop in living standards that implies.

This accident will teach us a lot about how to design and build reactors and nuclear power stations and maybe will delay the construction of those new plants which would be the real tragedy of this accident. We need to start building them now.

mmaro• 15 years ago

Reposting piguy314's [dead] reply:

It's instructive that we've already engineered ways of preventing the problems TEPCO is experiencing at their Fukushima. Many newer reactor designs have a passive residual heat removal system that removes decay heat even without electrical power to run cooling pumps.

http://www.ap1000.westinghousenuclear.com/ap1000_psrs_pccs.h...

brazzy3• 15 years ago

you need to learn some math. You are an environmentalist dupe

You need to learn some reality. You are a nuclear lobby dupe.

cousin_it• 15 years ago

Good answer. I actually don't know the figures, but I know what sort of argument it would take to convince me: some numbers showing that nuclear power production takes a substantially higher toll on life and health than other forms of energy production, measured by kWh. This number determines whether producing the same amount of power by other means is going to save people, or kill people. (Yes, it's not out of the question that environmentalist activism kills people. Good intentions don't protect from bad consequences.) Maybe the people who advocate stopping nuclear power should cite their acceptable figures of death toll per kWh produced, and then we can compare with oil and coal. Emotional arguments only get us so far.

As regarding sustainable energy, here's my favorite book on the subject: http://withouthotair.com . It takes the approach I like: "let's just sit down and calculate".

Element_• 15 years ago

Live geiger counter readings from Tokyo: http://www.ustream.tv/channel/geiger-counter-tokyo

Rough translation of the prime ministers speech on reddit: http://www.reddit.com/r/worldnews/comments/g3zel/breaking_ex...

squidsoup• 15 years ago

Kyodo News (http://english.kyodonews.jp/) are reporting that radiation levels in Chiba are twice to 4 times normal level and 33 times normal level in Utsunomiya, Tochigi.

cdellin• 15 years ago

Just a note - all radiation levels reported from around the plant are measured in milli(m)/micro(u)-sieverts(Sv) per hour. For comparison, the worldwide average background radiation level is approx. 0.274 uSv/h, and the usa recommended continuous occupational limit is 5.71 uSv/h. For example, the highest level I've seen reported is 400 mSv/h, or 70000x the recommended limit. Info from wikipedia.

Natsu3• 15 years ago

I feel bad for posting the same thing so much, but there are just too many discussions of this going on.

"As of 0:30 pm, the measured value of radiation dose near MP6 was 4μSv/h. The increase of the radiation dose cannot be confirmed at this time."

http://www.tepco.co.jp/en/press/corp-com/release/11031405-e....

I've seen lots of things reported, but I'm always leery of things that have gone through two or three languages to get to us. We've all played that translation party where things get translated into gibberish. I'm going to have to take it with a grain of salt when people get their news from the French embassy (which, last I knew, was not known for nuclear expertise, but feel free to prove me wrong).

Dramatic escalation in Japan (Fukushima Nuke Plant)

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