Printable View
Japan is well known for disaster preparedness and it's strict building codes. They've spent billions over the years to develop and use technologies to limit the damage from earthquakes & tsunamis. The death toll will probably be lower because of this effort and foresight, but it really is shocking how puny our efforts can be compared to the natural forces that drive this planet.
I wonder why the reactors weren't SCRAM'ed once the quake hit?
The quake damaged the equipment to do that.Quote:
Originally Posted by Xiahou
a very tragic event, I just hope everything will be ok and not much damage is done. My pray for you as well
My condolences to all.
As Japan braces itself for a second quake, another nuclear plant has lost its cooling system.
This does little to promote nuclear energy. We may have to rethink its proliferation. You can build them with the latest safety measures, with the physics guaranteeing thast these new reactors are 100% safe, guaranteed!, but apparantly nuclear plants simply have a tendency to blow up.
Yea I suppose we should ban Nuke power due to all the 8.9 earthquakes we get in France every year.Quote:
Originally Posted by Louis VI the Fat
Look at the number of explosions of nuclear plants.
Look at the number of explosions at oil refineries - without 8.9 quakes causing them.
Nothing is 100% safe. As yet there has been little more than a minor leak and no one has died. Compared to other causes of deaths in the world there are more important things to be worrying about banning.
~:smoking:
To be honest I be more worried about the long term environmental damage caused by all the fires especially the one at the big refinery.
Well to be fair this is a General Electric BWR type reactor. The GE design is apparently controversial and not all that modern. BWR's are generally somewhat behind the technology curve of safe reactors. Molten salt reactors are better, thorium even better.
Yes when they are hammered by 2 big earthquakes within a day of each other and the resultant tsunami. You have to realize that all large scale electrical generation not using moving water uses steam. A nuclear reactor replaces burning fossil fuels with Uranium/plutonium to heat the water into steam. Thing about steam is that it has a tendency to cause explosions when it goes uncontrolled.Quote:
Originally Posted by Louis VI the Fat
Also the Fukushima I facility has 6 reactors. Unit 1 is what blew, unit 3 was/is in danger of going the same way. Those are the ones being filled with sea water and boric acid. Fukushima II SCRAM'ed as soon as the power went out.
This isn't a steam pressure problem. This is an energy transfer from the reactor into steam which isn't kept moving which means that locally so much energy is “stored” in the steam that the bonds of the atoms from the water molecules in the steam are dissolved and the elements separated. This creates hydrogen and oxygen, which rises to the top of the structure (having a lesser density than steam). Away from this energy source (heat emitted from the core) these elements react into water again, i.e. ignition of the hydrogen gas. The energy required to split the water molecules is released as it were, and since nearly all hydrogen will react with the oxygen within the smallest timeframe, the resulting explosion is very powerful.
Now this danger is fairly unique to BWR reactors, because the temperature and the pressure required to make the steam absorb so much energy and then this energy to make the molecules disintegrate into their component elements is a combination of factors that you don't get much elsewhere. In fact to produce hydrogen you typically need to resort to electrolyse, but this is a much more controlled reaction (and once the power is cut the reaction stops). Since hydrogen is most often undesired (because it is so dangerous in the presence of oxygen) research goes into substitutes for hydrogen producing solutions to avoid it entirely.
Quote:
Originally Posted by Beskar
Seems pretty weird, guess the spring from above method is better than the pressure tank from below method then?Quote:
Originally Posted by wikipedia
I also wonder why noone on any news I've seen mentioned that the mechanics for the control rods had failed, they all sound like the cooling system was/is the only problem here with no other way to keep the reactors cool.
Then there is the issue of the batteries and the emergency generators being apparently the only way to power the cooling system, one expert mentioned that our reactors here have those, plus a way to attach external generators that can be brought in from elsewhere, which makes a lot of sense.
I don't think this shows why nuclear energy is bad and shouldn't be used at all as some are screaming, I think it shows why more money should be invested into it to think about how we can use it safely, and yes, that means it should be possible to replace a lot of the vital parts with ones brought in from outside and why the emergency systems should be kept very simple or at least have very simple, manual secondary controls. Oh and perhaps why BWRs should actually be phased out ASAP.
That said it's a really tragic event that seems to have spawned more tragic events, I'm sorry for the Japanese and wish them the best for their way through and out of this. :bow:
Some perspective from a physicist:
why i am not worried about japans nuclear reactors/
He posits that the explosion at Fukushima I unit I was caused by super heated and irradiated steam being pumped into the reactor building, but fully outside the reactors outer concrete layer, to relieve pressure inside the reactor. But that it was so hot that it actually broke the hydrogen bonds* in the water and it separated into pure hydrogen and oxygen. And both being highly volatile and explosive gases, they went up.
*Having taken chemistry in high school I know that to be no mean feat. Hydrogen bonds are among the strongest in nature.
I've been watching the news of this disaster with increasing horror as we see more and more of the devastation revealed. The scenes from Minami Sanriki are cataclysmic - reminiscent of the photographs of Hiroshima after the bomb. Nothing stands. A town of 17,000 people is mud and sticks. Perhaps 10,000 of those people have also been obliterated.
There is a film taken of the wave - a black, roiling creature of demonic power that simply arrives and overwhelms the things of Man, unstoppably brutal. And I am reduced to tears by the pictures of a tired man staggering into yet another shelter on his seemingly endless search for his family, shoulders slumped under the increasing weight of his hopelessness, only for a shriek of recognition to herald his wife grabbing him in a hug. The happiness and relief was so poignant that I could no longer watch the screen - and how many will not find joy, but only the scant consolation of a mortuary slab, or worse, nothing but memories.
Here is a link to a series of before-and after photos of areas hit by the tsunami. Draw your mouse across the "before" images from left to right to see the "after" image. Hard to imagine being in the middle of something like this.
http://www.abc.net.au/news/events/ja...eforeafter.htm
Wow. It's like a huge hand flattened everything there.Quote:
Originally Posted by Togakure
Look at the size of the splash when it hit a wall (in the first video)! Compare it to the car that was moving by. Fortunately, the video doesn't show anyone suffering. I'm appalled by this force of nature.
https://www.youtube.com/watch?v=hjorLr5MUvc
https://www.youtube.com/watch?v=TRDpTEjumdo
https://www.youtube.com/watch?v=i3jA1RKjriA
https://www.youtube.com/watch?v=wBt5VlZkdyY
How insignificant we are to the grand machinations of the planet. My condolences to all affected- I hope comfort can be found, somehow.
That's it, the plant has basically lost containment: http://www.bbc.co.uk/news/world-12740843
This is bad for a country like Japan with such a dense population, and it is going to kill nuclear energy.
More to the point, all those people have to go somewhere, but the Japanese infastructure is in pieces.
http://bravenewclimate.com/2011/03/1...e-explanation/
A very good explanation of what happened at Fukushima.
Unfortunately recent developments have rendered useless some of the facts.
For those who, like me, are tired of the breathless apocalyptic reporting on the incidents at the damaged reactors, I'd recommend keeping abreast of it via the IAEA website.
It's serious, but it's not Chernobyl and it's not going to be.
I'm so sorry for my cousins living far far east of here. Condolences. :shame:
Reading from the link Xiahou provided, the situation looks more like a wait-and-see kind rather than run-for-your-lives one. And I hope it goes along that route to being eventually totally contained.
:japan:
i note that the anti-nuclear lobby is going bananas at the 'opportunity' they have been presented, particularly in germany.
Well I think I would evacuate rather than wait for my fridge to run out of food and all services to be cut (power, running water) as the “stay in or evacuate” stage prolongs.
You need to calm down. This isn't some 50's era poorly though out soviet reactor. It's a western one, with 3 or 4 layers of protection between the outside world and the nuclear fuel. Including a metre thick box of concrete.Quote:
Originally Posted by Philipvs Vallindervs Calicvla
Well, yeah, the panic is a bit much, but if something should ever go wrong with our reactors I wouldn't want them to say "Oh, sorry, that area is contaminated now because when we brought in some external diesel generators, the plugs didn't fit..." so the security checks on the reactors can't hurt.Quote:
Originally Posted by Furunculus
The whole "Shut them all down right now!" thing is quite a bit too much though. I had to laugh a bit when I read people are buying iodine pills here.
Also the sooner we switch to renewables the better, so a bit of outrage doesn't hurt for now, it's also nice to see how quickly something can be done by the politicians once there is enough outrage. ~D
I find this whole "shut them all down" rage completely stupid. Nuclear energy is one of the cleanest and safest around and just because a 9 grade earthquake and a devastating tsunami destroyed a power plant and yet it still fights back, we decide to scrap every damn plan for them!Quote:
Originally Posted by Husar
Sweet idea.
Who said I was anything other than calm.Quote:
Originally Posted by lars573
Fact: Despite being one of the most meticulous and safety concious people in the world the Jananese have thus far been unable to contain the problem, at one point radiation reached potentially lethal levels around the plant, and there has just been another explosion. Also, all those safety features failed, it's a good thing the main containment unit thus far appears to be holding, is all I can say.
Nuclear Power is a false dawn, it won't solve out energy problems, or save the environment, it will just further stall the introduction of sustainable power, and it can cause serious and irreperable damage if there is an accident.
The Laws of Thermodynamics say otherwise.Quote:
Originally Posted by Philipvs Vallindervs Calicvla
All energy even solar is essentially nonrenewable on a long enough scale.
Also the energy we use everyday is limited by its scarcest resource/material, renewable energy is highly dependent on particular rare materials and is therefore limited by them.
Nuclear energy is also limited but it is far far more efficient and likely to last far longer than any quasi-sustainable energy source.
Edit: also I see a good news story that two people were found alive thats good some good news at least
Before we all sign on to bury our reactors in concrete, you all should figure out what it takes on an economy of scale magnitude to keep your Prius charged up and your Ipad glowing.
Do some order of magnitude calculations on the generation/liberation of energy. Ask yourself... would you rather live with broken mountains & sooty skies (coal), oil slicks and sooty skies (oil), an area the size of Texas covered in solar panels to power just Dallas (solar)... or show me how you would balance the demand/supply equation, and what you would do with the waste.
Nuclear power does a great job at much energy for little integrated negative effect. The problem is that the negative effects are highly concentrated. I'm not saying that's the answer, but tiling 2/3 of our land mass with cadmium isn't either (solar) me-thinks.