Japan Earthquake: nuclear plants

*robinson*

Quote by razzz

Does not compute. If all is well, why maintain a "fictional" exclusion zone?

Keeps out the reporters. And the crazies. Protesters early on rammed the gate and drove around Fukushima Diani for a good while (protesting loudly all the while) until they could catch them and arrest them.

Yes, in the middle of all the post quake/tsunami/meltdown at Daiichi, protesters breached the security at Diani and drove around inside the plant. In a truck.

The story wasn't played up of course.

joewein

Quote by elektrownik

Unit 5 is at atmospheric pressure so the question is if they are venting it sience earthquake ? I understand that is RPV is closed (it must be during pressure tests) the pressure shouldnt be at atmospheric level.

Units 5 and 6 are in cold shutdown, i.e. coolant is below 100 deg C and therefore the RPV doesn't have to be beyond atmospheric pressure to prevent boiling. Decay heat is being removed using the RHR system.

Borek

Quote by zapperzero

I can. For instance, some arrangement of gantry cranes, plus a wall or two might have thrown big "shadows", stopping much of the ejecta, while the rest went upwards. The outer walls of the reactor building may have reflected some of the blast, bunching up the debris cloud as it was forming. And so on and so forth.

Even if the SPF shaped the blast (which it may have), it does not follow that it was anything else but a hydrogen blast. The highest concentration of hydrogen would have been found directly above the pool, no? And the pool would have been only half-filled.

Discussion on the explosion is already buried deep somewhere in this thread. From what I remember speed of the explosion propagation heavily depends on the shape of the area (walls, columns, any other objects). No idea if that's enough to shape the explosion so that it is mostly vertical (that is, up becomes the path of the least resistance), but who knows.

*robinson*

Building One: Hydrogen explosion.

Building Three. Hydrogen plus something else.

Building Four: Unknown.

zapperzero

Quote by robinson

Building One: Hydrogen explosion.

Building Three. Hydrogen plus something else.

Building Four: Unknown.

At least make an effort to argue or source... such pronouncements add nothing of value.

rowmag

Quote by MiceAndMen

The articles in question are in Japanese, so quoting would be limited to Japanese text and asking someone to translate. We might ultimately end up with the whole article translated, which would completely be against the fair-use spirit of limited reproduction of copyrighted works. Then there is the matter of Japanese copyright law which I am totally unfamiliar with.

Being able to read the text would be nice, but my inability to read Japanese is my problem, not the author or publisher's. For the 2 articles in question, that's OK though because the diagrams and pictures convey substantial information by themselves.

My personal opinion is that most of the text does not seem very interesting unless one is a hardcore civil engineering otaku. The juicy bits of relevance for this thread are mostly in the illustrations, as you note.

I was using Google Translate to get some idea of the article text, but it's slow going. For example, first article, first section, title is
"1. まえかき"
which google translates as "For Example Oyster Or". I gave up soon thereafter.

Try "まえがき."

*robinson*

Quote by zapperzero

At least make an effort to argue or source... such pronouncements add nothing of value.

Please give us a source for your claim.

:)

Thinking about Building Three, it is highly probable that the building was full of not just hydrogen, but a lot of moisture. (this probably came up before, but I don't recall it at the moment)

If the hydrogen level was high, there wouldn't be enough oxygen to allow it to all oxidize at once, which clearly Building One suffered from. So the initial blast which clearly blew out the side allowed oxygen rich air to suck in, and the rest of the hydrogen went, but at the same time heating the moisture inside to turn into superheated steam, which would explain the obvious steam explosion. Obvious in the sense it clearly was not the type of instant flash you would see with a big hydrogen/oxygen explosion alone.

Experiments with concrete models and hydrogen, and hydrogen and a lot of moisture might actually learn us something about what can happen when you combine superheated boiling water pools, hydrogen, burning nuclear fuel rods, cesium hitting water, and various oils, gases and such, when it all goes terribly wrong.

*robinson*

Back to Power plant two:

Although the utility known as TEPCO told the agency that it will release the water after removing radioactive substances to an undetectable level, the agency is not approving the plan, leaving the fate of the 3,000 tons of the water accumulated in the nuclear power station, located 15 kilometers south from the crippled Fukushima Daiichi power plant, undecided.

If the water remains in tanks for a prolonged time, the storage facility may be corroded by salt in the water.

After being flooded by tsunami following a magnitude 9.0 earthquake that struck northeastern Japan on March 11, the Fukushima Daini power station saw about 7,000 tons of water accumulate in its facilities.

Of the water, 3,000 tons in the reactor, turbine and other buildings has been found to contain a small amount of radioactive materials such as cobalt.

TEPCO initially planned to let the water stay in the tank, but changed its mind after seeing rust in the storage facility and decided to release the water into the sea.

http://mdn.mainichi.jp/mdnnews/news/...dm090000c.html

While I don't believe most of what TEPCO reports, much less after it is filtered through the Japanese Government, something clearly went seriously wrong at Daini as well.

What exactly happened there seems shrouded in mystery.

zapperzero

Quote by robinson

If the hydrogen level was high, there wouldn't be enough oxygen to allow it to all oxidize at once

There would, if the hydrogen were to have been created by radiolysis of water into H2 and O2.

*robinson*

Of course, but that isn't what is supposed to have happened. Hydrogen was produced by metals oxidizing, so the oxygen was locked up in metallic oxides, it wasn't electrolysis of water going on. If that had been the case, the explosions may have been much more destructive.

tsutsuji

The NISA has summarized a number of informations about the water treatment facility in http://www.meti.go.jp/press/2011/06/...10609006-2.pdf (in Japanese).

That facility is meant to be an emergency facility running for one year, treating the 230,000 m³ that will have been produced until the end of 2011. After that a lasting facility could take over.

The 10,000 m³ contaminated water storage facility will be gradually built from mid August to the end of September.

2,000 m³ of radioactive sludge will be produced. 400 caesium absorption towers will be spent. The caesium absorption towers are installed in concrete box culverts. The sludge in pellet containers at the process main building. The absorption towers are designed to ensure that in a worse case scenario they don't heat more than 1°C per hour. The sludge will have a cooling system to remove the residual heat. Hydrogen production will be controlled with ventilation.

A series of precautions is listed against earthquakes. A 14 m high sea wall will be built to protect from tsunamis. All high level contaminated water equipments must be indoors with openings including doors being strong enough to resist tsunamis. The buildings must be watertight to prevent leaks into ground water... etc.

There is no fear of criticality, because no U or Pu is present in the water.

Measures against chemical hazards (explosions, worker's health) are defined.

By December, there will be a temporary storage facility for sludge. By September a temporary storage facility for spent caesium absorption equipments. A study for the end storage of the various waste products is started.

zapperzero

Quote by robinson

Of course, but that isn't what is supposed to have happened

According to whom?

jim hardy

Nuceng

thank you for the complete answer four pages back regarding PCV vent paths.

you painted a precise mental picture.

an aside - while catching up this am i noticed lots of conversation on H2.
here's another .gov study on it

Hydrogen Problems Related to
Reactor Accidents

hope i saved right link, it's a Danish study

http://www.iaea.org/inis/collection/...8/25028788.pdf

it's too highbrow for me to understand

but some of you folks will devour it.

old jim

tsutsuji

Quote by etudiant

Is it even realistic to think of evaporating 100,000 - 200,000 tons of water, apart from the contaminated steam aspect?
Seems to me they might need to restart unit 5 or 6 to supply that kind of heating.

According to the Mainichi quote written above at http://www.physicsforums.com/showthr...01#post3347501 the quantity angering the fishermen is only 3,000 tons. I don't really understand what is being planned for the other 7,000-3,000=4,000 tons. Is it so clean that Tepco is allowed to discharge it into the sea by the existing rules ?

Bioengineer01

Quote by sp2

I just now recalled that I posted this here, a month or so ago (#5257):

<<When TEPCO tells me it's 10% of Chernobyl, I'll assume it's most likely at least 20%, and I'm fairly sure that I at least won't be way high.
Could I be way low? Yeah, I suppose so, but I'll wait for better evidence to support that.
(And, if it *is* way low, there will surely be evidence of that, eventually. Even if it takes a while to seep out, so to speak.)>>

So what did they announce yesterday? That it's more like 20%.

(I'm now working off the assumption it's probably really more like 40%, but we'll see what happens.)

Again, if we apply Markov Chain prediction algorithms using the data already on the thread, worst case versus best case (normally officially supported by TEPCO), you can predict with 80% likelihood that it will be more than 40%, if I fix it at 40% then the probability level comes way down, difference between reported and "true" after two months situations predict a lot worse "true" scenarios. It was a fun exercise... :)

Bioengineer01

Quote by sp2

Well, it's certainly not thought to be linear.
TEPCO seems to suggest that it's been negligible after the first two weeks, so that initial total roughly equals THE total.

(Not that I necessarily *believe* that, but I think that's the 'official position.')

One thing I'm pretty confident of: the new number will eventually be exposed as nonsense, just like the old number was.

Then all the 'nuclear experts,' who pompously told us again and again that "this is nothing like Chernobyl; anyone who says it is is an idiot" are gonna be even more red-faced than they already are.

And they should be mercilessly held to account for it.

My understanding is that the reported number DO NOT include releases to the Ocean and only air releases and thus the statement that the worse is over. When they consider the true releases to the Ocean, my gross napkin calculations say that they already got Gold!

etudiant

Quote by tsutsuji

According to the Mainichi quote written above at http://www.physicsforums.com/showthr...01#post3347501 the quantity angering the fishermen is only 3,000 tons. I don't really understand what is being planned for the other 7,000-3,000=4,000 tons. Is it so clean that Tepco is allowed to discharge it into the sea by the existing rules ?

Apologies, there was confusion as to the items discussed.
The comment was in response to the Asahi quote in your posting 9418:
The desalinated water will be vaporized in the final step to reduce its volume.
http://www.asahi.com/english/TKY201106080177.html
which appeared to be in the context of the DaiIchi plant water treatment plan.

The 7000 tons at DaiNi seem to be quite an interesting issue in their own right, as the source of their contamination is not obvious. While one can hardly blame TEPCO for wanting to remove this radioactive seawater from their premises, the pattern of disclosure is once again not such as to inspire confidence.

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robinson Blog Entries: 1	Building One: Hydrogen explosion. Building Three. Hydrogen plus something else. Building Four: Unknown.