Japanese Tsunami

[Platapus]

Originally Posted by Freiwillige

On a positive note, I noticed there is really no looting or rioting or worse. Kudo's to the Japanese people for keeping their wits about them in this emergency situation.

Yeah, if this happened in the US, there would be rampant looting and probably vandalism.

[Penguin]

Looks like the situation is still on the edge...
Good to hear that our members DarkFish, zaza and their friends are well off!

Originally Posted by Platapus

Yeah, if this happened in the US, there would be rampant looting and probably vandalism.

Same here. You could hardly see any guards at the japanese supermarkets and people wait in line for hours. I already said that I have a deep rescpet for such a cool behaviour: http://www.subsim.com/radioroom/show...&postcount=149

Here people would loot the markets and steal the important stuff first - like alcohol and cigs....

[Platapus]

It is because Japan has a more collectivist culture than the US.

[Penguin]

certainly true for the culture, but I have the impression that as a rule of thumb for the US or Europe the people are more helpful in areas where people live more individual = in sparse populated areas and/or by people who value individuality.

And cultural norms are just one aspect. The "fight or flight" instinct is rooted deep inside us, even training and/or experience don't always overcome it.

Back to topic: Has anybody read any serious estimates how much heat is still inside the Fukushima reactors or much effect the cooling efforts had so far?

[Kptlt. Neuerburg]

From what I've seen and read in the news a fourth reactor at the Fukushima plant as exploded and the use of sea water doesn't seem to be helping every much if at all. It would seem that a total meltdown will happen sooner or later, I hope it doesn't happen at all. So far four out of six reactors have suffered explosions according to the BBC and CNN.
http://www.cnn.com/2011/WORLD/asiapc...ors/index.html
http://www.bbc.co.uk/news/world-asia-pacific-12749444

[Platapus]

Pretty messed up when you have aftershocks that are 6.1

[ASWnut101]

Small update.

The situation at Fukushima plant 2 (Fukushima Daini) has been stabilized, all four reactors have reached cold shutdown state.

Fukushima plant 1 (Fukushima Dai-ichi) is falling apart. All four containment buildings have been damaged or destroyed. Reactor two has lost essentially all possible cooling systems and is venting steam into the atmosphere. Unless a miracle occurs, they're going to lose that reactor and have a meltdown.
No update on the status of the other three reactors.

http://www.tepco.co.jp/en/press/corp...1031507-e.html

http://www.tepco.co.jp/en/press/corp...1031504-e.html


About the radiation, as some seem to be freaking out about it...

As I've said before, the steam contains short-lived, highly active radionuclides. The steam will produce large amounts of radiation, but only for a very short time (a few minutes). Cities outside of the evacuation area are under little threat of being enveloped by a radioactive cloud of death.

The radiation levels that are "7 times above normal" in Tokyo are nothing to worry about. It's still an extremely small dose. You'd put yourself at an immensely higher risk of injury or death by trying to flee the city than by simply staying put.



Also, because the steam is venting at a large rate from reactor two, there is little threat of an explosive meltdown. There's kind of a dilemma from this, though. You could either 1) continue pumping water on the core to try and cool it, but at the expense of having large amounts of steam escape into the air, or 2) stop pumping water on it and just let it melt, which would have it's own host of problems. It's going to be interesting to see how they handle this one.

[Oberon]

At least they're all able to vent, I was worried when the explosion in reactor two happened that the pressure release valve would be damaged, that rules out a steam explosion at least.

[Platapus]

And a meltdown and vessel compromise, while not a good thing, may be the only way to disperse the molten fuel to reduce it to non-criticality.

We are beyond the point of hoping for a happy ending. Now we need to focus on the least sucky bad ending.

The question is: What's underneath? And were these reactors constructed with a post compromise dispersement capability?

Anyway, mega kudos to ASWnut101 for the comments on radiation fear mongering. It is very easy for the public to be misinformed by misunderstanding what is being reported.

And way too easy for the news media to deliberately mislead the public in the interest of news revenue. Why a news media would feel it necessary to make this seem worse then it is. This disaster is not good enough for them?

[Oberon]

It's not just the public being mislead, the BBC earlier mentioned that one of their reporters caught PM Kan asking members of the Tokyo Energy Company "What the hell is going on?"

[XabbaRus]

I hope when you are talking about criticality you are only speaking about the reaction causing high thermal energy and not an explosion.

However if it melts through if it spreads out it will aid in cooling it down.

[Type941]

can someone clarify for me this. how long it takes to fully cool down the fuel? I mean from what i understand, the fuel rods once reaction is "activated" give off energy for 2-3 years at full power. But as they are now operating at 3% level it will take them decades to full cool. So they would rather have this crap melt and covered by concrete-lead and have it cooled much faster.

To put this into perspective, how long they need to pour water into reactors? years? months? the one plant is cooly shut down. This one is completely out of control and they may have not one, but up to 6 three mile island type insidents, 6 times more radiation, etc. It's still not chernobyl but still pretty fk.ing bad.

[Catfish]

News say Tepco has removed its technicians from the site at Fukushima since the situation is now out of control.
The inner containment of at least one reactor has blown up, they are measuring 400 millisievert "some kilometers away" ?!
And a shut-down reactor seems to have explodes as well (outer building)

Can anyone support or deny this ?
I don't trust Tepco for sure, but if even they say the situation is deteriorating it sure does not look good.



We have a japanese friend who went to Japan (Tokyo) on wednesday last week and have not heard anything since, i hope she's well

[Platapus]

Originally Posted by Type941

can someone clarify for me this. how long it takes to fully cool down the fuel? I mean from what i understand, the fuel rods once reaction is "activated" give off energy for 2-3 years at full power. But as they are now operating at 3% level it will take them decades to full cool. So they would rather have this crap melt and covered by concrete-lead and have it cooled much faster.

In a nuclear reactor the percentage of power is a complicated calculation. Cutting out about 20 pages of technobabble, one can visualize that a reactor running at "3%" can do this in several ways. The first thing that has to be defined is what do they mean by 3%? Percent of fuel use, percent of fission? Percent of heat? Percent of power? All mean different things. Just saying that the reactor as been operating at "3%" is ambiguous.

Let's assume that they are talking about 3% of fission.

1. Have 3% of their rods being bombarded with neutrons. (it would have to be more than a numerical 3% but like I said, it is complicated.
2. Have a subset of a full load in which about 3% of the fuel is being bombarded with neutrons.
3. Other much more complicated ways.

In any case, fission is an all or nothing event per fuel rod element. One can't "throttle" an individual fuel rod element. The only way to throttle a reactor is to isolate rods or elements of rods. Any element of a fuel rod that is being bombarded with neutrons is fissioning at its full rate. Criticality is criticality.

With that oversimplified understanding, it will take the same amount of time for any specific irradiated fuel element to cool. Whether it is a full rod's worth or only one rod element, same time. This is why it is generally better to cook a full rod instead of cooking multiple rods only partially irradiated.

This is because every irradiated fuel element will generate a specific amount of what is called Decay Heat. An irradiated fuel element continues to produce heat even after being taking out of a reactor. This means that before any "cooling" can take place, all decay heat (additional generated heat) processes must be over. Without sufficient cooling, an irradiated fuel rod will continue to generate heat. You can have a "meltdown" or a cladding compromise. with a rod outside a reactor (just ask the North Koreans about that)

Generally (taken with a large pinch of PU) speaking the Decay Heat process will take a period of Months to end. Like radioactive half-lifes Decay Heat does not suddenly stop, but slowly gets smaller and smaller until it gets to the point where it can be considered no longer adding significant heat to the fuel element.

Generally speaking, spent fuel rods are kept in wet storage (the water helps cool the elements as well as provides screening) for about a year. After that they can be moved to what is called dry cask storage where they will sit for a very long time.

Please note that all these times are general and that there are many many factors that will affect these times. But I think this simplification will suffice to answer your question.... I hope.

[RickC Sniper]

MSNBC is reporting that they are now seeing heat elevating at plants 5 and 6 in the complex and are considering venting them.

I do not understand this. I think 5 and 6 were not even operational when the earthquake happened. It was my understanding that under normal circumstances when you shut a reactor down the cores quit emitting heat in a matter of a few days...as long as the water coolant is there. Why would shut down reactors now be showing elevated temperatures?

http://www.msnbc.msn.com/id/42084187...s-asiapacific/

edit...nevermind. Platapus answered my question as I was posting it. Thank you.