8.9 Earthquake has struck Japan

[Ryan McGinnis]

They vent from the reactor itself; that's how the cooling works. The water directly cools the rods. Normally, this water is converted to steam, which runs through pipes to turn turbines and is then condensed and re-injected into the core.

What's been happening is that the water has been boiling and the steam pressure from inside the *reactor* has been directly released into the containment building (which blew itself up). This is why the water level drops; if you don't replace the water that boils away, soon there is no water left. All the pumps that replace the water are down and there is only one lone low-pressure firetruck left to replenish the water in all three reactors.

Normally the release of radioactive steam from inside the reactor wouldn't be a huge deal, since the radioactive steam release turns back into normal steam within seconds. The problem starts once the fuel rods become damaged, as at that point actual fission products are introduced into the steam, which are dumped into the containment building (which blew itself up) which are then introduced into the atmosphere. This is why the U.S.S. Ronald Reagan encountered a radiation level around 750 times normal background level 100 miles from the plant out to sea. An unknown quantity of of really bad long-halflife fission products are being dumped into the atmosphere.

The reason this is still better than the alternative is that if they don't dump the steam, the reactor eventually violently explodes and burns (a 'la Chernobyl). They're choosing to release small quantities of really really bad fission by-products into the atmosphere to avoid having the reactor decide to vomit the entire core into the sky. It's still a really, really big deal and I hope the radiation levels around the plant are nowhere near what they are 100 miles out to sea, since I don't think anyone is going to live in an area that is experiencing 200 REM of radiation per year.

 

[Darren Addy]

You are describing how cooling is supposed to happen. I'm finding multiple illustrations and text indicating that they have abandoned trying to do it the standard way and are instead flooding the Primary Containment vessel, which you explanation does not address. If they are not doing this, then that is where I am confused.

 

[MClarkson]

Amazing before and after shots of tsunami damage, which has wiped clean many areas in these shots. Some areas show more or less damage, ranging from only a small % of collapsed buildings to near 100%. The damage from this looks worse than category 5 storm surge... in that the hurricane isn't going to push quite as far inland.

http://www.nytimes.com/interactive/...te-photos-japan-before-and-after-tsunami.html

 

[Drew.Gardonia]

my geology professor at MTSU, Dr. Mark Abolins sent me this link and thought I'd share if anyone's interested.

http://serc.carleton.edu/NAGTWorkshops/visualization/collections/japan2011.html

 

[Ryan McGinnis]

You are describing how cooling is supposed to happen. I'm finding multiple illustrations and text indicating that they have abandoned trying to do it the standard way and are instead flooding the Primary Containment vessel, which you explanation does not address. If they are not doing this, then that is where I am confused.

They are not pumping water into the drywell portion of the primary containment vessel (as far as I know -- not sure what the point of that would be as it wouldn't help cool the rods at all); the water is being pumped into the core. See this NPR illustration to see what I mean:

http://www.npr.org/2011/03/14/134545461/interactive-inside-japans-nuclear-reactors

 

[Jim Saueressig]

The idea is to flood the reactor core to cool the melting rods, the problem is the temp at a few thousand degrees flash boils the water turning it into the steam, this builds the pressure that is having to be released into the atmosphere with the radiation at this point because it cannot be cycled back as cooled water. Trying to control the venting of this radioactive steam without dumping all of the radioactive material into the air is the issue. They could just flood the piss out of it if they had the equipment to move that mass quantity of water but it all has to come back out and all of the radio active material would be free flooding the atmosphere.

If I understood your question....

 

[Jim Saueressig]

Damage much?

 

[MClarkson]

Why is there no steam from reactors 1 and 2? and the only steam from 3 was after the explosion. Does that not imply that the reactors are not being cooled at all?

EDIT: Core#2's housing structure has exploded as well.

 

[Darren Addy]

EDIT: Core#2's housing structure has exploded as well.

We assume that is what it was, but no confirmation yet.

From translation of nhk japan page:

has become clear that there is damage to the equipment connected to the reactor containment vessel, called Sapuresshonpuru cover.

Apparently they mean the suppression pool shown in the first illustration on this page:
http://www.ucsusa.org/nuclear_power/nuclear_power_risk/safety/concerns-about-relying-on.html

From BBC:

The explosion is feared to have damaged the reactor's pressure-suppression system, Kyodo says. It adds that "radiation tops legal limit" after the explosion.

Slightly better that it blows now than 9 hours from now: http://www.windfinder.com/forecast/sendai_airport_shinko

EDIT: they cannot currently explain if the supression pool was damaged by an explosion unrelated to the reactor itself, or if the supression pool was the source of the explosion. Is the roof of the building still there? - NHK World TV interviewing officials live

 

[Jim Saueressig]

Kyodo Reporting .

Blast heard at 6:10 a.m. at Fukushima's No.2 reactor: gov't (08:02)
Suppression pool may have been damaged at No. 2 reactor: gov't agency (08:07)
Radiation tops legal limit after blast heard at Fukushima nuke plant (08:16)
Higher radiation levels measured in Ibaraki -- south of Fukushima (08:28)

 

[B Ozanne]

From cnn.com archives:

12/28/2004: 33,000 dead
12/29/2004: 56,000
12/31/2004: 134,000
1/1/2005: 150,000

The current recognized death toll is 200,000+ from the 2004 Indian Ocean Tsunami.

From a country that literally invented the word tsunami you'd think they would put a nuclear power plant and it's vital backup machinery just a little farther from the ocean. What is the general design criteria for a nuclear power plant? A 500 or 1,000 year event? Was this a 500 year event or possibly only a 100 year event?

 

[Robert Rohloff]

They are also reporting the wind is now from the NE and pushing it over land and not out to sea.

 

[Ryan McGinnis]

From what I've read their critical failure was in trusting the sea walls to keep the water out of the nuclear reactor's backup diesel generators. Japan has invested an extremely large amount of money in sea walls under the assumption that they could slow or even stop a tsunami. While the walls did slow the tsunami a little bit, I think it's safe to say they didn't do much to stop it.

Also, the walls were constructed to stop the tsunami from a quake of a smaller than 9 magnitude. A magnitude 9 was not foreseen as it has never happened near Japan in recorded history.

In the future, I'm sure they'll put the generators on higher ground. Hard to believe they didn't do that already -- seems almost criminally negligent, given how over-engineered the rest of a nuclear plant is.

 

[Ryan McGinnis]

They are also reporting the wind is now from the NE and pushing it over land and not out to sea. Is the suppression pool the main draw of water to put into the reactor core?

Yeah, I was using that model Aaron posted last night to do trajectories for today; it predicted that the winds would take particulate from the reactor over the mainland for much of today before the wind shifted and started taking it out to sea again by tomorrow. I figure we'll know in a hurry if there is any really significant radiation pouring out of that plant, as all it will take is one person in Tokyo with a Geiger counter and one person in the media to prove it.

 

[Darren Addy]

The live report seems to indicate that damage to the container vessel (called the "last line of defense") has occurred at No. 2. Suppression pool pressure dropped indicating that damage may have occurred.

They are being cautious, but seem to be close to admitting the most serious problem yet on unit No. 2.

After the explosion, pressure inside the chamber went down. This would not happen with a vented hydrogen explosion, which occurs outside the containment vessel (and blows the containment building roof off). That does NOT appear to have happened at No. 2. (at least not yet that I have seen)