So I just read that a second nucular reactor in Japan has a failed cooling system and they will need to release "a small amount of gas" from the reactor to relieve pressure.

This is nonsense.  A "small amount of gas" will not relieve the pressure for very long.  These reactors are basically boiling vessels, and the only way that pressure rises is by the internal coolant being heated way beyond its design levels.  True, pressure can be relieved by releasing gas, but you have to continuously release the "gas" (really radioactive-contaminated steam) more or less continuously, because the heat from the reactor keeps generating more pressure.  The only way to relieve that pressure is to either (a) stop the heat source (they cannot, as the reactor is already in its lowest power phase), (b) get the cooling system working again (this has failed so far), or (c) allow coolant to boil off into the atmosphere as a gas, with high probability of it being radioactively contaminated.

Furthermore I have been reading that the Japanese have been attempting to cool these reactors by introducing sea water.  This means that the regular reactor coolant is going somewhere... my guess is, in the form of steam boiling off in order to keep the pressure (and temperature) down. Either that, or the reactor coolant is leaking somewhere... again, not a good outcome.

Japanese authorities need to come clean about this... now.  The truth is gonna come out eventually anyway.  And as we all know, bad news only gets worse the longer you try to hide it.

Oh, one other thing.  The various media reports indicate that when the fuel rods reach 4000 degrees F, the uranium pellets would start to melt.

But... long before that would happen, the Fukushima reactor would already have paddled down sheet creek.  The reactor vessel itself is made out of steel, and the melting point of steel is around 2800F, give or take 100 degrees.

Temperatures inside the reactor vessel have already reached 2200 F, as that is the temperature at which the hydrogen gas is generated from the zirconium cladding of the fuel rods reacting with the hot water.  By the time the fuel gets to 4000F, there is no reactor vessel as a hole will have already blown through it and the water will all be gone.

By the way, given that the temperature has already reached 2200F, this means that the reactor vessel by now is glowing red.  Not a good situation.

If any of our inthe00s buddies are anywhere near Fukushima, I would advise you to GET THE HELL OUT OF THERE.  If they don't get that thing under control there could be a huge radioactivity-release problem if the reactor pressure vessel fails.

As far as I can tell from the TEPCO press releases (which are updated hourly, and the Japanese ones are more informative than the English ones), the reactor SCRAMmed correctly, but for whatever reason (maybe an M8.9 earthquake when the reactor probably wasn't designed to withstand more than a 7.5, or maybe a 20-foot tsunami), the generators failed.  No generators, no coolant pumping.  Switch to backups and you can at least recirculate existing water in the core, but if you've got a leak, you're going to need to replace that water.  

If you can't replace that water (oh, maybe your generators are down...), the coolant level will drop.  Fuel assemblies will get hot, some of that water will turn to steam, building up pressure.

And the higher the pressure, the harder it is to pump coolant into the system.  So you vent some steam (through filters that take out most of the crap) in order to increase your odds of getting coolant into it (or to decrease the rate at which coolant is being forced out of it).


This is nonsense.  A "small amount of gas" will not relieve the pressure for very long.  These reactors are basically boiling vessels, and the only way that pressure rises is by the internal coolant being heated way beyond its design levels.  True, pressure can be relieved by releasing gas, but you have to continuously release the "gas" (really radioactive-contaminated steam) more or less continuously, because the heat from the reactor keeps generating more pressure.  The only way to relieve that pressure is to either (a) stop the heat source (they cannot, as the reactor is already in its lowest power phase), (b) get the cooling system working again (this has failed so far), or (c) allow coolant to boil off into the atmosphere as a gas, with high probability of it being radioactively contaminated.


You got most of it right, but you also forgot...

(d): Wait long enough, and you'll find some other way to release the pressure.

pg4uogOEUrU

:)

OK, quick layman's overview of 1960s/70s boiling water reactors.  

http://i.imgur.com/Oj4kg.png

It being the 70s (this thing went critical 40 years ago and was scheduled for retirement and decomissioning in less than two weeks), they didn't have an external (tertiary) containment buildings under negative pressure to contain anything they had to vent.  So any venting had to be to the atmosphere.  That was before it did the big firework.

The big firework appears to be a hydrogen explosion - that little yellow *flash* just before the shockwave goes straight up, and bits of what appear to be sheet metal go flying everywhere.  Question is, how'd all that hydrogen get there?  Reaction between steam and zircalloy cladding around the fuel?  Bad, because it indicates that the core's exposed and Really Freaking Hot.  Leak of hydrogen from nearby turbine building?  Not so bad.  Since we don't know which, and since we do know that coolant levels were low, let's assume it was from steam reacting with the cladding of fuel assemblies.  Still, looking at what's left and comparing it with the diagram above...

http://i.imgur.com/fYKKN.png

...I speculate that secondary containment - the concrete stuff around the pressure vessel - is somewhat compromised, but not horribly so, and that the pressure vessel itself is also intact.  It looks far more horrific than Three Mile Island, but it might not even be that bad.  

That said, I wouldn't be surprised if another one of these goes in a similar manner.  Fukushima Daiichi #3 supposedly achieved cold shutdown - and yet a press release issued in the past hour reveals a new problem.  There are also problems at Fukushimi Daini, but they started later, and are consequently not as severe as the ones at Fukushima Daiichi.  

The good news is that none of these reactors are critical.  The SCRAM worked, the control rods were inserted, and the reaction stopped.  What we're dealing with here is residual decay heat of all the crap that's normally burned up - around 7% of reactor output at the moment of SCRAM, and (I'm guessing) 1-2% right now, and falling rapidly.  As long as they can keep them cool with water for just one or two more days, they can still save 'em - and everyone downwind.  

Cooling with nice distilled/deionized water means you might get to reuse the reactor.  Seawater and Borax will work just as well - but you won't get to reuse the reactor, so it's your last-ditch effort.  That's what they're doing now on the one that went *poof*.  (Not too surprising, given that I doubt that whatever was left the already-damaged cooling systems was able to survive that.)

The hard call is deciding when to give up and pee on the proverbial spark plug.  "After there's enough hydrogen built up to blow the skin off the top floor of the building" is too late to save the industry, but believe it or not, it's still not too late to save the day.


If any of our inthe00s buddies are anywhere near Fukushima, I would advise you to GET THE HELL OUT OF THERE.  If they don't get that thing under control there could be a huge radioactivity-release problem if the reactor pressure vessel fails.


But yeah, that.  The evac radius of 20km will keep you safe (for values of "safe" that include "if you're downwind and 20km away, keep moving") even in that event.  They went from a 3km radius when nothing was leaking (levels at the plant were normal, but they knew they had a problem), a 10km radius when they were venting steam (and levels at the plant were comparable to flying at 35,000 feet), and to 20km when the fit hit the shan (and levels at the plant are now at the point where you probably don't want to work there for more than a month.)

Y'all should know I'm not much of a pollyanna.  I don't like the radiation levels I'm seeing post-*poof*, but the odds are still in favor of the scenario that this will be over, and that it'll be safely shut down within hours/days, not weeks.  

RIP, "person was seriously injured on the trapped exhaust stack tower crane cockpit" (I speculate either at the moment of explosion or as a result of an aftershock), and who didn't make it.  And yes, to the other 10000-50000+ who didn't make it.  The whole country had a Really Bad Day.

But even the worst-case scenario here is unlikely to be anywhere near Chernobyl.  To put this in perspective, at Chernobyl, that big concrete done didn't exist, and instead of water, they used flammable graphite.

For 70s tech, these things have held up remarkably well.  That ol' reactor sure lasted a lot longer than the oil refinery. 

Thanks for the info LB and Foo.
:)

I was afraid it was going to be worse.  If the SCRAM could not be performed or failed, I thought of the possibility of a meltdown in which the core would be bared to the atmosphere.  Could have been x100 worse than Chernobyl.  However, maybe it's prejudice, but I have a lot more confidence in the Japanese than either the Russians or the Americans handling a nuke plant emergency, even in the throes of earthquake/tsunami aftermath.

On the other hand...

I did not,nor do I now, expect the Japanese government to tell the whole truth and the cancers and mutations resulting for radioactive release might not appear for years or decades.

I was afraid it was going to be worse.  If the SCRAM could not be performed or failed, I thought of the possibility of a meltdown in which the core would be bared to the atmosphere.  Could have been x100 worse than Chernobyl.  However, maybe it's prejudice, but I have a lot more confidence in the Japanese than either the Russians or the Americans handling a nuke plant emergency, even in the throes of earthquake/tsunami aftermath.


Confidence:

Yanks and Japanese:  Plenty.  The TEPCO press releases are actually pretty good - you just have to compare 'em against the English ones with Google Translate. 

Russians: Not much.  The RMBK design at Chernobyl was optimized for something other than power generation.

On the other hand...


I did not,nor do I now, expect the Japanese government to tell the whole truth and the cancers and mutations resulting for radioactive release might not appear for years or decades.


This may change as the situation changes, but at the moment, if the numbers are correct - and they're not the sort of thing that can be lied about - we're nowhere near the level at which anyone not working at the plant is at risk.  (And of the people working at the plant, they're more at risk from industrial accidents and aftershocks than radiation exposure.)

This may change as the situation changes, but at the moment, if the numbers are correct


...well, that didn't take long.  The situation has changed.

Shovel the PDF through google translate.  The numbers at the bottom of the list are in the GTFO now category.

Thanks for the info LB and Foo.
:)

I was afraid it was going to be worse.  If the SCRAM could not be performed or failed, I thought of the possibility of a meltdown in which the core would be bared to the atmosphere.  Could have been x100 worse than Chernobyl.  However, maybe it's prejudice, but I have a lot more confidence in the Japanese than either the Russians or the Americans handling a nuke plant emergency, even in the throes of earthquake/tsunami aftermath.

On the other hand...

I did not,nor do I now, expect the Japanese government to tell the whole truth and the cancers and mutations resulting for radioactive release might not appear for years or decades.



Like you, I have more confidence in the Japanese than I do in the Americans. I'm sure you know about Vermont Yankee (since you live closer to it than we do). Entergy (the company that owns it) is trying to extend the 40 year contract that ends next year. They are trying to tell us that it is safe when in the past two years, a cooling tower had collapsed, there had been mega underground pipes leaking tritium into ground water (when they were saying that there were no underground pipes), etc. etc. And the NRC has approved it to operate it for 20 more years. OY VEY!!!! It has nothing to do with safety as it has to do with profits.


Cat

Like you, I have more confidence in the Japanese than I do in the Americans.


Actually, TEPCO has a less-than-admirable reputation on the safety front:

http://en.wikipedia.org/wiki/The_Tokyo_Electric_Power_Company#Scandal

That said, I wouldn't be surprised if another one of these goes in a similar manner.  Fukushima Daiichi #3 supposedly achieved cold shutdown - and yet a press release issued in the past hour reveals a new problem.


"So, finally I go over to the computer and I log myself on and just as I suspected,
It's some big fat hydrogen buildup with an ignition source and only one more layer of containment.

T_N-wNFSGyQ

Oh, man, I hate it when I'm right."
 - Weird Al Yankovic, AlbuquerqueFukushima!

Tonight's fun?  Apparently all those bits of building landed in the wrong places on unit 2, and the used fuel pool at (shut down since before the earthquake) unit 4 is doing... wrong things.  (Yes, even as I plumb the depths of gllows humor to try to cope, I can still find useful information from people who know what they're talking about.  Benefits of a classical education.  Anyone within 20-30km of that thing who isn't actively involved in saving the world shouldn't panic, but they need to GTFO.  If they've been paying attention to their evacuation orders, everyone within 20km has had at least 24 hours to GFTO, so they've got that going for 'em.)

Well, the next day, the inthe00s board had this contest to see who could correctly guess the amount of fallout coming from the TEPCO CEO's butt.
I was low by 3 orders of magnitude, but I still won the grand prize.  That's right!  A first-class, one-way ticket, to

http://img849.imageshack.us/img849/5083/fukushima.jpg

(The flight attendants ran out of Dr. Pepper and salted peanuts, and the inflight movie was The China Syndrome with Jane Fonda, and oh yeah, three of the reactors melted down and we landed in the middle of a tsunami and the Nikkei crashed and everybody died.)

Anyone for a big bowl of sauerkraut?

Well by now the owners of the Fukushima (Lucky Island) power plant have probably crapped enough bricks to build an entire new plant.  :o

Far as I can tell they really have not done anything definitive to stop this problem as it is getting worse with each day, and now we are (3 days after some of already figured it out)  being told that the reactor water level has dropped below the fuel roids in the reactors.  The spent fuel rod storage pool problem is also wild.  From what I have been reading, the pool has started to boil.  They need to get a firehose in there ASAFP just to keep the water level up.  If they dick around long enough for the cladding to melt/react in the spent fuel pool (I do not know if that is a possibility for spent fuel) then they are way, way forked, big-time.

This is a textbook case of a company's management trying to cover up a problem.  The Japanese government needs to do its freaking job and take over that work site (assuming that it is not a conspirator in the coverup).  >:(

Well by now the owners of the Fukushima (Lucky Island) power plant have probably crapped enough bricks to build an entire new plant.  :o

Far as I can tell they really have not done anything definitive to stop this problem as it is getting worse with each day, and now we are (3 days after some of already figured it out)   being told that the reactor water level has dropped below the fuel roids in the reactors.  The spent fuel rod storage pool problem is also wild.  From what I have been reading, the pool has started to boil.  They need to get a firehose in there ASAFP just to keep the water level up.  If they dick around long enough for the cladding to melt/react in the spent fuel pool (I do not know if that is a possibility for spent fuel) then they are way, way forked, big-time.

This is a textbook case of a company's management trying to cover up a problem.  The Japanese government needs to do its freaking job and take over that work site (assuming that it is not a conspirator in the coverup).  >:(


It reminds me of a song about Three Mile Island --

The empire burns
The umpire's not laughing
The president's resented,
The ambassadors's a night club
You cannot get it out

It's stuff you cannot taste or see
It's stuff you cannot smell
It's stuff that's twenty times as hot
As the hottest stuff in hell

Harrisburg oh Harrisburg
The plant is melting down
The people out in Harrisburg
Are getting out of town
And when this stuff gets in
You cannot get it out

The company said it would not blow
The government said it might
Harrisburg oh Harrisburg
I wonder who is right

Who can leave it behind, the curtains are drawn
There's something I must say to you
You cannot get it out

--Midnight Oil
"Harrisburg"

--Midnight Oil
"Harrisburg"


What, no Kraftwerk?  (Heartbreak of my childhood, I tell ya, when I realized it wasn't a song about how cool physics was.  Hey, it's not my fault I couldn't speak German and barely knew Morse! :)


Far as I can tell they really have not done anything definitive to stop this problem as it is getting worse with each day, and now we are (3 days after some of already figured it out)   being told that the reactor water level has dropped below the fuel roids in the reactors.  The spent fuel rod storage pool problem is also wild.  From what I have been reading, the pool has started to boil.  They need to get a firehose in there ASAFP just to keep the water level up.  If they dick around long enough for the cladding to melt/react in the spent fuel pool (I do not know if that is a possibility for spent fuel) then they are way, way forked, big-time.


Keep in mind that we're now well outside the problem space in the textbooks.  This is an Apollo-13 "figure it out as you go along, and failure is not an option" situation.

Situation still fluid (LOL).  EU dude needs to put a sock in it.  NRC officials suggest #4's pool is dry, TEPCO officials disagree.  Reason for US 50mi/80km evac zone vs JP 20mi/30km evac zone is due to NRC having a slightly different radiation exposure limit, and is no cause for alarm.  Helicopter drop on #3's spent fuel pool was done from a higher altitude due to high levels over the plant.  Presence of steam after one of the drops indicates some fuel rods in #3's pool were at least partially exposed.  Choppers can't get water to #4's spent fuel pool because holes in #4's roof aren't in the right place.  Power line slowly being constructed and approaching the plant; this, if the pumps are still operable, will help greatly.  Meanwhile, JSDF forces have been bolting lead plates to the sides of police/SDF water cannon vehicles, and that attempt to cool the spent fuel in #4 will take place in the next few hours.  

Keep your fingers crossed.  World ain't ended yet.  No risk to people in North America.  Negligible risk to people in Tokyo.  Minor risk to people immediately downwind of this thing.  British Embassy Site's interview is probably the most informative summary I've seen coming from any government involved.  And remember, by the time you read this, the situation will have changed again, so get ye to some primary sources like an NHK feed, or commentary from livebloggers who can translate Japanese, etc.

Crap.  I forgot a joke.  Quick and dirty, to put a number on the risk to North Americans, even if the fecal matter hits the rotary oscillator and the fuel actually ignites, the resulting poopstorm will be detectable in North America, but to riff on a line from Gwen Stefani (this is a pop culture board, after all), the poop will be Bananas.  B-A-N-A-N-A-S.

What, no Kraftwerk?  (Heartbreak of my childhood, I tell ya, when I realized it wasn't a song about how cool physics was.  Hey, it's not my fault I couldn't speak German and barely knew Morse! :)

(this is a pop culture board, after all)  


Okay then:

http://www.youtube.com/watch?v=c98qdFQF7sw

:-\\

Okay then:

(Alphaville - Big in Japan)

:-\\


Mojo Nixon wasn't very big in Japan, but what he sang with bitter irony, I sing with inebriated conviction! 

Oh, this world is at a tremble at its strength and mighty power,
They're sendin' up to heaven to get the brimstone fire,
Take warning, my dear brother, be careful how you plan,
You're workin' with the power of God's own holy hand!

http://www.youtube.com/watch?v=eyYSjmuMPJc

(Damn.  Somebody, pro-nuke or anti-nuke, has so got to make a video of that track :)

If it were up to me I'd skip the last verse, because it's in poor taste even by my standards (standards?  I have standards?  Eew!  Get 'em offa me!)  But the first verse is basically an anthem for people who've worked with the stuff - even the atheists.

When the Cascadia subduction zone goes, it'll do to me what just happened to Japan.  The shaking, liquefaction, and subsidence that killed 20-50K people (and will do at least 10-100 times that body count when Cascadia rips, because unlike Japan, the United States is completely unprepared for it) is what will kill me.  The nukes are the least of my concerns. 

srs bznz: So far, this guy's real-time feed of Tokyo rad levels has remained at background.  (To scale, people just outside the plant's exclusion zone should worry if his graph hits 100.  People in Tokyo probably shouldn't worry until it hits a few hundred thousand, which it won't.)  JSDF dudes continue to throw water in the general direction of the plant.  Due to possibility of compromised containment, as of this writing, IAEA ranks Units 1, 2 and 3 at Three Mile Island, and Unit 4 at not-quite-as-bad-as-TMI.

And for the record, nobody died at TMI.  The only guy killed by this incident was some poor guy who happened to be on or near the crane when Unit 1 did the big firework.

I continue to predict that (apart from a few workers at the site who'll get a few months' vacation due to radiation exposure), the only casualties of this incident will be people in California who pooped themselves from hyperkalemia while taking unnecessary potassium iodide.  That prediction gets retracted if the pools run dry and the fuel catches fire.  But as of this writing, it doesn't look like that's going to happen.  And it's becoming increasingly unlikely as power has been restored to the site, and the pumps for unit 5 (and presumably, very soon, unit 6) are working.  

http://www.youtube.com/watch?v=2SUDZ30_PXg

(Also pretty big in Japan)


Speaking of which, this is Japan, where even a nuclear incident needs to be explained using cute cartoon characters.

5sakN2hSVxA

And, of course, poop. 

It's actually a pretty clever analogy - to grossly oversimplify, think of radiation as the stink, and contamination as the poop.  Since most of us are in North America, I'll go with a car analogy.  Radiation exposure is what you get when you drive past the spot where the skunk got flattened.  Drive into the area, it starts smelling bad, drive out of the area, and you stop smelling the skunk.  Contamination is the guy whose car actually hit the skunk, and his car will smell bad until he gets himself to a car wash with a good underbody-cleaning spray and actually washes the stuff off.

And Japan?  It's great to see you getting back on its feet and resuming deliveries of WTF to a world that so desperately needs it.  Good on y'all.

Speaking of which, this is Japan, where even a nuclear incident needs to be explained using cute cartoon characters.

5sakN2hSVxA

And, of course, poop. 

It's actually a pretty clever analogy - to grossly oversimplify, think of radiation as the stink, and contamination as the poop.  Since most of us are in North America, I'll go with a car analogy.  Radiation exposure is what you get when you drive past the spot where the skunk got flattened.  Drive into the area, it starts smelling bad, drive out of the area, and you stop smelling the skunk.  Contamination is the guy whose car actually hit the skunk, and his car will smell bad until he gets himself to a car wash with a good underbody-cleaning spray and actually washes the stuff off.

And Japan?  It's great to see you getting back on its feet and resuming deliveries of WTF to a world that so desperately needs it.  Good on y'all.


To continue the analogy... The cartoon character who was standing in front of that big fan when all that poop got thrown into it is gonna be impossible to clean up and is gonna stink for a really long time.  ;D