Risk of Nuclear Catastrophe Escalates in Japan – ‘Worse than Chernobyl’

[bananas]

http://blogs.forbes.com/williampentland/2011/03/11/risk-of-nuclear-catastrophe-escalates-in-japan-worse-than-chernobyl/

Risk of Nuclear Catastrophe Escalates in Japan – ‘Worse than Chernobyl’
Mar. 11 2011 - 4:06 pm

The Institute for Public Accuracy issued the following statement by nuclear expert, Kevin Kamp, about the risk of nuclear disaster in post-Earthquake Japan: “The electrical grid is down. The emergency diesel generators have been damaged. The multi-reactor Fukushima atomic power plant is now relying on battery power, which will only last around eight hours. The danger is, the very thermally hot reactor cores at the plant must be continuously cooled for 24 to 48 hours. Without any electricity, the pumps won’t be able to pump water through the hot reactor cores to cool them. Once electricity is lost, the irradiated nuclear fuel could begin to melt down. If the containment systems fail, a catastrophic radioactivity release to the environment could occur.”

“In addition to the reactor cores, the storage pool for highly radioactive irradiated nuclear fuel is also at risk. The pool cooling water must be continuously circulated. Without circulation, the still thermally hot irradiated nuclear fuel in the storage pools will begin to boil off the cooling water. Within a day or two, the pool’s water could completely boil away. Without cooling water, the irradiated nuclear fuel could spontaneously combust in an exothermic reaction. Since the storage pools are not located within containment, a catastrophic radioactivity release to the environment could occur. Up to 100 percent of the volatile radioactive Cesium-137 content of the pools could go up in flames and smoke, to blow downwind over large distances. Given the large quantity of irradiated nuclear fuel in the pool, the radioactivity release could be worse than the Chernobyl nuclear reactor catastrophe of 25 years ago.”

Kamps is a specialist in nuclear waste at Beyond Nuclear and conducted research last year assessing the state of nuclear facilities in Japan.

Meabwhile, Japan has ordered thousands of residents near a northeastern nuclear power plant to evacuate today following a massive earthquake that caused a problem in the plant’s cooling system, according to the Associated Press.

[laconicsax]

1. Yikes!

[rhett o rick]

75. Mr. Kamps appears to have an agenda. He was unnecessarily alarming. nm

[bananas]

84. No, he wasn't unnecessarily alarming, as is now obvious six days later.

See posts #82 and #83.

[gateley]

2. Even if Kevin Kamp is wrong, if it's not "worse than Chernobyl", WHEN are we

going to learn to stop FUCKING WITH THAT STUFF? As hard as it is for some to believe, some things are beyond our control! :grr:

[LiberalEsto]

3. +10000

[jillan]

7. +1000000

:mad: :mad: Mad right along with you.

[madokie]

15. So am I, madder'n a wet setting hen

Like Gateley said when are we going to quit messing with this shit?

Rec

WRONG NAME, SORRY

[Confusious]

23. Exactly!

Man wasn't made to go faster then a horse could take 'em. These new fangled iron horses will turn your innards to goo!

[DeSwiss]

4. K&R

http://www.csmonitor.com/USA/2010/0330/Nuclear-power-Obama-team-touts-mini-nukes-to-fight-global-warming">Nuclear power: Obama team touts mini-nukes to fight global warming

[1776Forever]

5. I pray this doesn't happen! I was always questioning why CA built their plants when they too have

such large percentage of earthquakes? Never made sense to me.

Nuclear power and earthquake zones overlap in the U.S.
Earthquake in Japan raises concerns about what could happen in the U.S.
Fri, Mar 11 2011 at 1:43 PM EST

http://www.mnn.com/earth-matters/energy/blogs/nuclear-power-and-earthquake-zones-overlap-in-the-us

Nuclear power is under the microscope as much of the world watches the aftermath of the Japanese earthquake and the resulting tsunamis.

Fires near Japanese nuclear power plants are forcing evacuations and concerns for all the obvious reasons. Those concerns have traveled across the Pacific to California, where nuclear power plants are being shut down.

(more at link)

[dixiegrrrrl]

6. 'Radioactive" in your sig line ...unintended creepy.

Right now Japan is terrifically creepy, since the jet stream from there comes directly to the West Coast.
Where my family lives.

[bananas]

12. Good point - I remember how they tracked the fallout cloud from Chernobyl

as it went over Europe and America.
A lot of farm produce had to be thrown away even in America.

[dixiegrrrrl]

59. The Chinese would just sell the damn produce

as they are selling heavy metal contaminated food ( vegetables and milk) already.

[amandabeech]

61. I seem to recall that the contaminated produce here was a result of Three Mile Island

and not Chernobyl.

The air currents move west to east in the TMI area. I lived there for several years.

[dixiegrrrrl]

8. Speaker on Al Jazeera: did the dome sustain any damage?

" The ( nuclear plant) dome is the only thing between massive radiation and the people.
No one knows if it is damaged,
no one knows if the dome can hold unless it is vented,
no one knows if venting will prevent a meltdown."

[rhett o rick]

20. Please, please, the dome is the SECONDARY containment. That means it is the SECOND

containment against the release of contamination and radiation. And that is only if the plant melts down.

[rhett o rick]

22. I was wrong, according to the link below the "dome" is the third containment

against release.

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=439x618106

[kristopher]

26. There are no domes in the video footage.

They have containment buildings, but there are no domes so it is premature to judge the situation by that reference.

[AtheistCrusader]

27. Language Barrier.

[kristopher]

29. I don't think so.

The "barrier" is the assumption at the linked post that the containment for the Fukushima reactors is the same as the containment where the poster worked.

[AtheistCrusader]

31. We shall see.

I've seen aerial footage of the plant. Sure, they arent 'domes', but what the hell else would you call them?

[kristopher]

34. Chernobyl had a "containment system" that didn't use a dome.

Recognizing the differences in reactor technology I believe this facility dates back to the time of Chernobyl. The first reactor was started in the mid60s.

[AtheistCrusader]

35. The RBMK type reactor at Chernobyl is a 'partial containment'

absolutely nothing at all like the light water reactors in Japan. Does not even resemble. Fukushima has FULL containment shells.

[FBaggins]

40. Yeah... like some people are "partial virgins"

It's using the same word for an entirely different thing. The core was not in anything that resembles "containment" to modern reactors.

This reactor is an older design and we can already see some of the advantages of the newest designs by comparison (I bet they're wishing they had a water supply that didn't need a pump right about now), but it's still significantly safer than Chernobyl. Even a partial meltdown shouldn't create a release anything like chernobyl's (here's hoping we never find out of course).

[kristopher]

41. I'll believe that about the containment when I see a schematic

No offense but the biggest source of misinformation I've encountered is from the pronuclear posters here. I understand the difference in basic design, but that doesn't tell us squat about the containment design of these specific reactors.

It would be great of you could back up your assertion regarding the containment design. I have a lot of friends in Japan and it would be nice if I knew a bit more about this specific facility.

[AtheistCrusader]

42. Fukushima 2,3, and 4 are Mark II Improved containment vessels.

Fukushima 1 is a Mark I, iirc.


I should elaborate, there are two 'plants', Fukushima 1 and 2, each have multiple reactors.

Fukushima II has Mark II improved containment vessels.
Fukishima I is Mark I.

Another way to describe it, depending on the news reports you are reading, the plants are Fukushima Diani and Fukushima Daiichi. Daiichi has 6 reactors. 3-6 were off for maintenence. 1-3 are affected. Diani 1-4 are affected.


If i read the translated media right, Fukushima Daiichi 2 was the first to have problems, and 1 is now having problems as well. These are GE Mark 1 boiling water reactors. Full containments.

[FBaggins]

45. Question...

...how can you understand the difference in basic design but not understand the containment design?

What is more "basic" about a given reactor design than what form of containment it uses? PWR vs BWR probably comes close... but really?

[kristopher]

52. Graphite moderated vs water as a moderator

The basic reactor design within the reactor chamber is what I'm referring to. The graphite moderator at Chernobyl was integral to the accident. The containment system that exists outside the reactor vessel was subject to some pretty wide variance in the late 60s and early 70s when these were built and I refuse to accept *assumptions* that treat the situation as if there were a standardized design that was being use.

From a post by madokie:

[FBaggins]

53. Got it.

Reasonable enough.

[AtheistCrusader]

54. Yeah, that's not used at this site. These are GE BWR Mark I's.

Edit: Like Vermont Yankee, Brown's Ferry, etc.

TMI was a PWR, so not even similar to that incident.
These ARE old reactors, using the 'light bulb and inner tube' containment type housing (I think it looks like an upside down turnip but whatever). Still, failure is only a risk, not a certainty by any stretch right now.

[FBaggins]

55. Actually three different designs and a 4th on the way.

From wikipedia

Fukushima I - 1 BWR 460 MW
Fukushima I - 2 BWR 784 MW
Fukushima I - 3 BWR 784 MW
Fukushima I - 4 BWR 784 MW
Fukushima I - 5 BWR 784 MW
Fukushima I - 6 BWR 1,100 MW
Fukushima I - 7 (planned) ABWR 1,380 MW
Fukushima I - 8 (planned) ABWR 1,380 MW

[AtheistCrusader]

58. 4-5-6 were 'cold' offline when this happened.

Only 1-3 are 'in play', if I understand the translated news right. All Mark 1's.

[FBaggins]

39. Hey! I think you got one right!

I don't think that this design has a dome.

[rhett o rick]

63. So you dont think. That says a lot. How do you make that decision? Because you cant see a dome?

I would hope a liberal would be more curious and want the facts before running off half cocked.

[AtheistCrusader]

64. It's not shaped like a dome, and it's inside the building. It's shaped roughly like

an upside down turnip.

[dixiegrrrrl]

56. They used the word "dome" ...while showing square buildings.

Language barrier, not to be taken literally, apparently.

[FBaggins]

60. It's bound to be more than a language barrier.

What kind of nuclear experts would one expect on AJ?

There aren't exactly a bunch of reactors in their target demographic areas. :)

[rhett o rick]

62. And I dont imagine we can visualize a dome within a square building. why think the worse. This is

Japan and not Russia. Big difference.

[Vincardog]

9. I just heard from a talking head on CNN that he was glad this happened, There is NO danger and he

was happy it demonstrated the safety of nuclear energy.

[fascisthunter]

10. the risks of having nuclear power plants...

...are the risks ever worth it? I don't think so... I hope from here on more attention and funding is spent on alternatives. It can't happen overnight, but incidences like this should give countries a clue on the dangers of NOT investing in alternatives.

[PamW]

69. Risk analysis is premature

..are the risks ever worth it? I don't think so...
================

I think it's premature to make that assessment. We don't yet know
what the consequences are.

We made the mistake of rushing to a premature assessment after the
Three Mile Island accident. In the final analysis, TMI was very minor.
Nobody was killed, and nobody was injured. Some "claimed" to be injured,
and sued, but their case was dismissed without a jury trial:

http://www.pbs.org/wgbh/pages/frontline/shows/reaction/readings/tmi.html

Three Mile Island was hyped like the current Japanese incident is; but
turned out to be a minor event in terms of the public health. Why don't
we wait and see what actually happens in Japan before making judgments.

If the radiation exposure is minor, and no member of the public is harmed,
then this incident will have a lesser impact than an airliner crash in terms
of adverse effects to the public.

Even when we have airliner crashes that kill a hundred people or more; we still
don't abandon air travel. If the effects of this incident are less than an
airliner crash; why would we abandon nuclear power when we don't abandon air travel?

PamW

[fascisthunter]

70. lol... wow...

I would puke but the attempt is very amusing and well sick at the same time.

[PamW]

72. What's wrong...

I would puke but the attempt is very amusing and well sick at the same time.
============

What's wrong with waiting to find out just what the consequences of this
incident are? What's wrong with making *informed* decisions?

Let's see what the effects are.

Even with the release of some radiation, the effects on public health may
be less than the crash of an airliner. Airline crashes really kill people,
but we don't abandon air travel because of a crash. We find out what the
problem was, and make air travel safer.

Nuclear power is extremely successful in terms of safety. It takes a
mega-quake like this 8.9 magnitude one to uncover a deficiency in the
safety of a nuclear power plant.

I'm sure the "lessons learned" will make nuclear power even safer.

The scientific approach is to learn from problem, and not run away.
We wouldn't have the technology we have today if we abandoned a technology
when the current state of the are was found wanting.

PamW

[rhett o rick]

11. I do not support nuclear power, but we should be aware that Mr. Kamps works for an organization

that is against nuclear power and not unbiased. I am not an expert but I can see a number of holes in his argument here. There are a lot of "if's" and "could's" and maybe some misinformation. The spent fuel in the pools is not very dangerous and that's why they arent in a containment. Yes the spent fuel needs to be kept cool but remember it's spent. If circulation ceased the water would indeed get hotter but how long to boil away is in question here. I doubt it is in the hours or even daysn and even then I dont believe an explosion would occur as stated.
Again I am not supporting nuclear power, and not saying there isnt reason for concern, but I dont put much weight in Mr. Kamps story. He has an agenda.

Now having said that, I do want to point out that these stores of spent fuel at private reactors are a hazard, but most likely not from natural disasters. But to me they are a dangerous target for terrorists. Instead of finding a permanent storage in a mountain, we allow tons of spent fuel to be stored "temporarily" at reactor sites around the nation.

[bananas]

13. Kevin Kamps information is correct and accurate

http://belfercenter.ksg.harvard.edu/publication/364/radiological_terrorism.html

It is estimated that, in the case of a loss of cooling, the time it would take for a spent fuel pool to boil down to near the top of the spent fuel would be as short as several hours, depending on the cooling time of the discharge fuel. <13>
...
Footnote 13: As an example, if a core had been loaded into the spent fuel pool five days after shutdown, it could take about eight hours to boil down. For details see: US Nuclear Regulatory Commission, Briefing On Spent Fuel Pool Study, Public Meeting, November 14, 1996; www.nrc.gov/reading-rm/doc-collections/commission/tr/1996/19961114a.html , p. 27.

edit to add: Obama's science advisor John Holdren association with the Belfer Center: http://belfercenter.ksg.harvard.edu/experts/140/john_p_holdren.html
(since you're questioning sources)

[rhett o rick]

18. Mr. Kamp didnt give facts. He said as your quote says "depending on the cooling time of the

discharged fuel." So what was the cooling time for the fuel in question? Mr.Kamp doesnt know. And he fails to point out that water can easily be added to the pools if they start to get hot.

Again, Mr. Kamp stated a lot of "if's" and "could's". IF they dont get their primary electricity on line and IF they cant get their back-up generators running, and IF they cant get auxiliary generators on line we COULD have a melt down. He didnt discuss whether the plant has a emergency cooling system that doesnt need electricity, like gravity fed. He doesnt mention that this plant may have a last ditch method of killing the core. Then he said If the primary containment fails and if the secondary containment fails. Why would we expect these containments to fail?
He literally gave no facts about this plant.

[AtheistCrusader]

28. They can also dump in boric acid and cadmium and such to quench the fuel further.

Lots of stuff can be done.

Portable generators are likely already being airlifted in. We've already dropped off coolant they can use.

[bananas]

44. They just expanded the evacuation zone to 10 lm

It was 3 km, and they expanded it to 10 km.
That's not a good sign, the situation is getting worse, not better.
Kamp gave the facts, this is a very serious situation, and it can become worse than Chernobyl.

[AtheistCrusader]

47. And if they didn't people would be screaming about the lack of caution.

I prefer an overabundance of caution. Good sign, etc.

[rhett o rick]

74. It appears that nuclear "expert" Mr. Kamps was wrong.

The plants were brought under control as designed for in emergencies. Some radiation was released but not harmful unless you were in the immediate vicinity. Nuclear plants have dangers and I do not support their use for economic reasons, but I hate to see misinformation used to spread panic.

[FBaggins]

77. Of course he was. But it's still important to recognize that this was too close to disaster.

The good news is that newer designs already protect against almost everything that went wrong in this event and it should be possible to retrofit new safety measures to those older reactors without too much trouble (additional batteries, a tertiary backup generation system, whatever).

The key here is that containment structures are the last line of defense. It appears (with incomplete information of course) that they did their job as designed...


... but those last-line-of-defense measures should never be needed.

[rhett o rick]

78. Those "last-lines-of-defense" were not tested here. They didnt even come close to needing them.

They are needed only if the core starts to melt down. The first lines of defense failed as the electric power was lost. The second line of defense the emergency generators also failed. But in the mean time the reactors were shut down, thus reducing the need for cooling. A third line of defense is an emergency cooling system which operates out side the normal electric and diesel generators. I am not sure what system these reactors use but this third line of defense wasnt needed because electric power was restored. A fourth line of defense also wasnt needed where chemicals are added to kill the core which stops the generation of heat. All of those would have to fail to need the last lines of defense.

I am not saying there isnt danger, just saying that some people were a little early with their "the sky is falling" predictions.

[FBaggins]

79. There has clearly been some amount of core damage.

At that point, containment is in play.

Some core-related elements were introduced into the environment. It doesn't appear that there were dangerous amounts of them, but what is clear is that without the containment vessel, it would have been far worse.

Yes, obviously a total meltdown would have presented a more significant test of those containment structures, but a partial meltdown plus an explosion that takes out the building that containment resides in... is clearly testing whether that containment design was adequate.

The long and short of it is that containment is designed as the last-ditch attempt to keep significant radiation from escaping. It appears to have performed that function. That's gotta be a "test". It isn't a "stress test" that runs right up to failure, but it's a test.

I don't think we're all that far apart here.

[rhett o rick]

80. yes I agree. Thanks for the discussion. nm

[CRH]

14. Thanks for that little bit of sanity, ...

Though I too am against nuclear power, and am concerned of the Japan situation, the amount of hysteria and outright misinformation of this story is incredible.

I notice in post five, as in the article linked in that post, they are claiming California nuclear plants are shutting down. In reading through the headlines, only alerts have been given of possible tsunami, Diablo Canyon and San Onefre are both are in a status of alert, but operating normal. That is very different from being shut down.

[rhett o rick]

19. I do not support nuclear power for electricity production. I am against trying to scare people

with out having facts. There may be a problem there, but the articles I have read didnt include facts that would allow us to make a judgment.

[FBaggins]

43. You've got the correct read on it. This behavior is unconscionable.

There was another story earlier that talked about a massive nuclear disaster from a handful of west-coast reactors that wouldn't (supposedly) be able to handle a tsunami of this size.

It was written by a guy who wants nothing more than to get rid of all nuclear power. It's fine for him believe that and even advocate for it, but these kind of fear mongering tactics when many people have died today and there's a legitimate reactor problem going on is just wrong.

Did he ever mention that California doesn't get tsunamis like that? IIRC, the worst one in west coast history killed something like a dozen people and we really need to argue about whether or not a particular reactor can handle a 50-ft wave?

This is much the same kind of fear mongering.

[bananas]

67. unconscionable? 300,000 evacuated from 'exclusion' zone, which has expanded to 20 km

You probably think it's unconscionable that the Japanese government is scaring 300,000 people by evacuating them from their homes.

http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=439&topic_id=622475&mesg_id=623353

26. 300,000 evacuated from 'exclusion' zone

#
1427: More than 300,000 people have now been evacuated from homes in northern Japan and that number will rise as the government increases the exclusion zone around the Fukushima nuclear power plant, Kyodo reports

[FBaggins]

68. Yes. It's unconscionable

You probably think it's unconscionable that the Japanese government is scaring 300,000 people by evacuating them from their homes.

Not a bit. Why would you think that?

You seem to assume that public safety responses (not just nuclear) revolve around doing as little as absolutely possible.

In reality, they always try to go well beyond. We evactuate hundreds of thousands in front of a hurricane even though there was no danger than 100s of thousands were going to die. You just want to go above and beyond to get the risk as close to zero as possible. We evacuate whole towns in front of a forest fire, not just the six homes along the current edge. Most of the time people would have been perfectly safe staying in their homes. But why take a chance?

I can't describe the massive gap between proper caution to evacuate anyone who might be impacted, and telling people that "worse than chernobyl" is on the table. Why not tell them that it's POSSIBLE that godzilla will rise up and collect all of the reactor fuel from around the country (containment can't possibly stop him) and he's going to pile it up in the middle of every major city? 70% of the japanese population will be destroyed!

A "worse than chernobyl" event would impact FAR more than people within a 20km radius.

[PamW]

71. What made Chernobyl so bad...

I can't describe the massive gap between proper caution to evacuate anyone who might be impacted, and telling people that "worse than chernobyl" is on the table.
=====================

I agree with you. Saying "worse than Chernobyl" is blatant fear-mongering.

What made Chernobyl so bad was that the reactor caught fire. The energy from
the fire served to loft radionuclides high into the air so they spread farther.

This reactor can't catch fire like Chernobyl. The reason Chernobyl could catch
fire is that it used flammable graphite as a moderator. The moderator for the
Japanese BWR is water, which doesn't catch fire, and neither do the metals and
ceramic fuel that compose this Japanese reactor.

PamW

[Systematic Chaos]

16. The fact that the huge refinery blowing up and spewing tons upon tons of RADIOACTIVE...

...fossil fuel waste into the air, which will effect the entire planet when the air currents are done with it, gets absolutely no mention in this thread just speaks volumes.

Fucking makes me sick.

[stuntcat]

17. ty

the footage I've seen on tv looks like a number of oil refineries are just burning up completely. fycking heartbreaking.

[AtheistCrusader]

30. Somewhere on the East Coast is a coal plant happily belching more radiation

than this reactor has (assuming the reports are accurate) leaked so far.

[Systematic Chaos]

33. My point, exactly.

Then, multiply that by all the coal, oil and gas plants around the world.

NNadir might be rude and grumpy, but he's one sharp tack. More people need to get past the attitude and actually read and study his links. It works wonders for putting shit into perspective.

[diane in sf]

36. He's a nnon-factual nnuclear proponent.

[Systematic Chaos]

37. Your career in actually debunking him with those things called facts needs some serious work.

Don't quit your day job just yet.

:D

[PamW]

73. Well put.

Don't quit your day job just yet.
===================

Well put. A good response to the "content free" style of post.

PamW

[OnlinePoker]

57. I notice he's absent from any of the Japanese nuke threads. n/t

[Confusious]

21. They don't have anymore diesel fuel or batteries in japan?

Wow, who knew? They don't even have one of those new fangled whirly birds to fly it in?

[rhett o rick]

24. The below link provides the best info so far.

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=439x618106

[jwirr]

25. How many reactors do they have in Japan? They just said a 2nd

one is heating up.

[kristopher]

32. There are 4 at that facility.

This link shows a photo
http://www.latimes.com/news/nationworld/world/la-sci-japan-quake-nuclear-20110312,0,2627198.story

[FBaggins]

48. Actually six.

Look a bit to the right.

And two more under construction IIRC that will each be almost twice the power of the average of the other six.

[AtheistCrusader]

50. Two sites.

But you're right, there are three 'live' reactors at the 'problem site'.

4,5,6 were 'cold' offline when this happened.

2 was the first to have problems, 1 has joined it.

[Fledermaus]

38. If they cant cool it, it will start to separate the water left in to a combustible gas mixture.

My guess is thats what maybe vented. Radioactive Oxygen and Hydrogen. Not a fun time in the control room right now.

[FBaggins]

46. It will start to separate the water into a combustible gas mixture?

Really?

A reactor can do that if you add specific reagents to the water as a catalyst. Some have even speculated on using them as a source of hydrogen for a "hydrogen economy" (though it doesn't sound wise to me). Are you under the impression heat alone will do that?

On edit... maybe a heavy water reactor could do it. I'll have to think about that. But that's still not an issue here.

[Fledermaus]

65. Well, what now jackass? Mabe ylou can have my post removed because I called you a jackass.

[FBaggins]

66. Lol... feel free to call me whatever you like`

There clearly was an explosion.

Still don't know what the mechanism is without the thermochemical reagents, but I can't deny that something blew.

[FBaggins]

76. For the record MG, you were wrong.

PamW's post #15 on the thread linked below explains the reaction that makes sense (assuming this was a hydrogen explosion)

Your theory that the reactor core, if uncooled, would split water into radioactive hydrogen and radioactive oxygen was, as expected, nonsense.

http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=115&topic_id=277993&mesg_id=277993

[Merchant Marine]

49. The following was posted on reddit.com by a nuclear engineer

After scram (complete shutdown), about 5% is still there and that level reduces in half every 15 minutes. So for a 3000MW thermal reactor (like this one), 600MW is still there after immediate shutdown, 300MW 15 minutes later, 150MW 30 minutes later, and so forth.
In a Boiling water reactor of that model, there are 3 cooling pumps in series (one for the cold feed and two after each hot feed loop). During a scram, those pumps must be shut off so that you don't get vibrational feedback (which could break a pipe). However, in the core is designed such that there are jet pumps (16 in parallel on the standard design) on the wet stream loop. This jet pump has no moving parts but can circulate the some water regardless of what the pumps are doing. Further, there is an single emergency main pump on the main loop that can push the full coolant load. This pump can be driven by any one of several diesel systems or a battery backup.
If all of this fails, you then start to depend on the cold water back up re-condenser. In a BWR, underneath the first reactor containment, there is a large torus shaped area that is filled with a large amount of water. You can drop the steam from the reactor into this ring. The steam recondenses and reduces pressure. With the jet pumps, you can push the cold water into the reactor. This system can prevent first containment failure but doesn't prevent core damage.
Then there is a second level containment. The design based accident for this reactor is assume a main coolant pipe dissappears (double guillotine break), all of the coolant flushes out and there is no way to cool down the reactor. In this case, 600MW post scram level will melt the reactor and possibly damage first containment, but second containment can hold the total heat produced post scram. You also have a coreium (term for molten core) catcher that catch the core, mix in a huge amount of radiation shield, and reduce the temperature.
What is happening: Earthquake happens, core is scrammed because something might break. When the scram happens, main pumps turned off, emergency main pump turned on. However, the diesel generator doesn't work, maybe damage in earthquake, maybe something else. They turn on the battery system. It can last 4 hours, which is enough to reduce core power to 10kW. However, it is hot in there and 10kW is still enough to continue to make steam. So the water level (which tells you how much steam has been made) is dropping. They can go to the recondenser if they need to, but the recondenser doesn't rule out core damage (not melting, but material warping and oxidation) which would be expensive or impossible to repair. So for now, they are bringing in new coolant so they can prevent expensive core damage.
They are NOWHERE close to the design based accident, and there is very little worry about containment failures. They are doing the evacuation because there isn't the safety factor they want, not because they are anywhere close to a radiation leak.

[FBaggins]

51. Some assumptions in there that I don't think apply to this reactor.

But the general thrust of it appears correct. What we've seen so far (based on very incomplete reporting) is a LONG way from a core meltdown or anything even approaching Chernobyl.

It's a big deal because the chances are many MANY times greater than they were yesterday at this time. Worthy of great concern (including evacuations and emergency measures), but not panic.

[bananas]

81. kick. nt

[bananas]

82. French nuclear officials say it could be worse than Chernobyl

http://www.telegraph.co.uk/news/worldnews/asia/japan/8387051/Japan-nuclear-plant-Just-48-hours-to-avoid-another-Chernobyl.html

Japan nuclear plant: Just 48 hours to avoid 'another
By Gordon Rayner and Martin Evans 10:52PM GMT 16 Mar 2011

Nuclear safety officials in France said they were "pessimistic" about whether engineers could prevent a meltdown at the Fukushima power plant after a pool containing spent fuel rods overheated and boiled dry.

<snip>

Thierry Charles, a safety official at France's Institute for Radiological Protection and Nuclear Safety (IRSN), said: "The next 48 hours will be decisive. I am pessimistic because, since Sunday, I have seen that almost none of the solutions has worked." He described the situation as "a major risk", but added: "All is not lost."
Asked about the maximum possible amount of radioactive release, he said "it would be in the same range as Chernobyl".
The incident at the Chernobyl nuclear power plant in Ukraine on April 26 1986 is estimated to have caused 57 direct deaths, with some 4,000 additional deaths from cancer.

Francois Baroin, a French government spokesman, went further, saying: "In the worst of cases, it could have an impact worse than Chernobyl." He added: "They have visibly lost the essential of control."

<snip>

Via http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=439x672263

[bananas]

83. Physicist Michio Kaku warns that Japan nukes may go 'beyond Chernobyl'

Posted earlier today by Tx4obama in the General Discussion forum:

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=439x673762

Physicist Michio Kaku warns that Japan nukes may go 'beyond Chernobyl'
http://crooksandliars.com/david-neiwert/physicist-michio-kaku-warns-japan-nu

Rachel Maddow - total amount of Spent Nuclear Fuel Rods in the pools at Dai-ichi plant
http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=439x666399

Maddow Video with fuel graphs: http://www.msnbc.msn.com/id/26315908/ns/msnbc_tv-rachel_maddow_show/#42121003