Earthquake in Japan....9.0...ouch!

Does anyone else feel sort of helpless? :(

Really feel for the Japanese people. Makes you glad to live in boring old Britain. We have sort of become used to seeing bad things happen in third world countries, so I think because Japan is an affluent country like ours it really hits home.
 
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Ricochet J said:
The opex from this incident would be a good learning tool. From my understanding they had a loco (loss of coolant). Can I just stress at that point the rods would drop automatically, and the reactor would be flooded with boric acid to stop the chain reaction.
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The Control Rods will have gone in yesterday at the first sign of the earthquake.

The main problem is the decay heat. Once the reactor is shut down, the fission process ceases but you still have to deal with the immediate radioactive decay heat that accounts for roughly 7% of the heat of a reactor at full power. The good news is, if you can call it that, is that the decay heat reduces pretty much exponentially over time and so the longer this goes on the more the situation will improve.

I work in the nuclear industry and this is definately concerning but you have to bear in mind when the news put out the word of "radiation leaks". The quantities that you are talking about here are really very small but it is only because the radiation limits are so tight that this is being blown out of proportion.

Take for example the gas fired power plant near Sellafield. They originally wanted to build it on the Sellafield site but were told no as the inherent radioactivity of the gas would mean that the site would breach its limits as a Nuclear Licensed Site. Therefore they built the thing outside of the fence instead!
 
CraigN said:
Its a boiling water reactor. that explosion looks like steam pressure built up too much.

The actual reactor is within a steel container.

http://en.wikipedia.org/wiki/Boiling_water_reactor
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I think thats a bit of a simple view of the situation.

The problem is the steam pressure comes from the reactor, so if you are losing coolant then reactor is at risk of melting.
 
Russia Today have been reporting that the backup generators for pumping the coolant (water) failed, could they not have just brought the whole plant back online instead of relying on backup generators?
 
mmj_uk said:
Russia Today have been reporting that the backup generators for pumping the coolant (water) failed, could they not have just brought the whole plant back online instead of relying on backup generators?
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Not really, as they would have to check the reactors etc to make sure they were not damaged in any way.
 
Jonnycoupe said:
I think thats a bit of a simple view of the situation.

The problem is the steam pressure comes from the reactor, so if you are losing coolant then reactor is at risk of melting.
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But at this stage, it is very likely that if any core internals do begin to melt, they would be entirely contained within the Reactor Pressure Vessel, and indeed further contained within the Containment building. The outer cladding that was blown away in the explosion seems to me to be quite typical of quite a lot of the older sites, it serves no safety purpose. As to why the explosion happened, I can't quite figure yet.
 
mmj_uk said:
Russia Today have been reporting that the backup generators for pumping the coolant (water) failed, could they not have just brought the whole plant back online instead of relying on backup generators?
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I'm not 100% sure but I would have thought that the reactors produce their own power, without the backup gens there would be no power to do such a thing. With the rods receding no power is being generated. It would be like trying to start a car with no fuel and no battery
 
physichull said:
The Control Rods will have gone in yesterday at the first sign of the earthquake.

The main problem is the decay heat. Once the reactor is shut down, the fission process ceases but you still have to deal with the immediate radioactive decay heat that accounts for roughly 7% of the heat of a reactor at full power. The good news is, if you can call it that, is that the decay heat reduces pretty much exponentially over time and so the longer this goes on the more the situation will improve.

I work in the nuclear industry and this is definately concerning but you have to bear in mind when the news put out the word of "radiation leaks". The quantities that you are talking about here are really very small but it is only because the radiation limits are so tight that this is being blown out of proportion.

Take for example the gas fired power plant near Sellafield. They originally wanted to build it on the Sellafield site but were told no as the inherent radioactivity of the gas would mean that the site would breach its limits as a Nuclear Licensed Site. Therefore they built the thing outside of the fence instead!
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I understand that as soon as the words "radiation leak" are mentioned, the public do worry - unfortunately the nuclear industry has that stigma attached to it. I also work in the nuclear industry and I'm sure you know as well as I do that most of the kit will be designed to seismic standards. We can only wait and hope that the loss of life isn't as much as we expect.
 
mmj_uk said:
Russia Today have been reporting that the backup generators for pumping the coolant (water) failed, could they not have just brought the whole plant back online instead of relying on backup generators?
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The generators would be to control decay heat waiting for the thing to cool off with a compromised cooling system/structure. The last thing they would want is to start making electricity with the plant tubines just to run the cooling pumps that are trying to maintain the reactor pressure vessel.

Old age - radiation embrittlement of the pressure vessel aswell which isnt good when the pressure starts ramping up like this!
 
LOAM said:
I'm not 100% sure but I would have thought that the reactors produce their own power, without the backup gens there would be no power to do such a thing. With the rods receding no power is being generated. It would be like trying to start a car with no fuel and no battery
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The power usage of the coolant pumps use is phenominal, it is therefore likely that the best solution was to shut the reactor down and deal with the decay heat (which is initially roughly 7% of the heat of the reactor at full power). Unlike Chernobyl, the reactor was firmly shut down, when the reactor is operational, the rods merely "dip into the bottom of the core", as boron in the primary coolant actually controls the reactor at full power. The rods can then have maximum effect when they are inserted (in this case the control rods are inserted from the bottom of the RPV as is typical of BWR's).
 
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