Japan Nuclear Coverage

[cowiz]

I don't know what kind of idiots design nuclear power plants

Is it the joos?

[Gawdzilla Sama]

I don't know what kind of idiots design nuclear power plants

Is it the joos?

No, it's Gawd.

[Don't Panic]

I don't know what kind of idiots design nuclear power plants, but requiring persistent power to ensure that there isn't a meltdown or explosion is monumentally dumb. When power is cut, the nuclear reactor should have fail safe mechanisms to cool the core down for a duration needed to reach safe temperatures. Requiring mechanical pumps that use power to do so and are prone to hiccups is a death sentence. What should be required is a water tower that stores water at elevation. It would be connected to the cooling system of the core but would be held back by solenoid values that require power to stay closed. When the power goes out, the solenoid valves open and the water from the water tower pours in to cool the reactor. The valves are sized so that a persistent rate of flow is obtained for the time needed. THIS IS WHAT IT MEANS TO BE FAIL SAFE.

Yes, because pouring a large amount of cold water on a nuclear pile is a good idea.

[Gawdzilla Sama]

I don't know what kind of idiots design nuclear power plants, but requiring persistent power to ensure that there isn't a meltdown or explosion is monumentally dumb. When power is cut, the nuclear reactor should have fail safe mechanisms to cool the core down for a duration needed to reach safe temperatures. Requiring mechanical pumps that use power to do so and are prone to hiccups is a death sentence. What should be required is a water tower that stores water at elevation. It would be connected to the cooling system of the core but would be held back by solenoid values that require power to stay closed. When the power goes out, the solenoid valves open and the water from the water tower pours in to cool the reactor. The valves are sized so that a persistent rate of flow is obtained for the time needed. THIS IS WHAT IT MEANS TO BE FAIL SAFE.

Yes, because pouring a large amount of cold water on a nuclear pile is a good idea.

Yeah, for the joos!

[Gawd]

I don't know what kind of idiots design nuclear power plants, but requiring persistent power to ensure that there isn't a meltdown or explosion is monumentally dumb. When power is cut, the nuclear reactor should have fail safe mechanisms to cool the core down for a duration needed to reach safe temperatures. Requiring mechanical pumps that use power to do so and are prone to hiccups is a death sentence. What should be required is a water tower that stores water at elevation. It would be connected to the cooling system of the core but would be held back by solenoid values that require power to stay closed. When the power goes out, the solenoid valves open and the water from the water tower pours in to cool the reactor. The valves are sized so that a persistent rate of flow is obtained for the time needed. THIS IS WHAT IT MEANS TO BE FAIL SAFE.

Yes, because pouring a large amount of cold water on a nuclear pile is a good idea.

What do you think they've been doing to the nuke piles right now? Hint: Water. And you don't pour directly on, it goes through the cooling tubes so it doesn't make direct contact, duh.

[Gawdzilla Sama]

I don't know what kind of idiots design nuclear power plants, but requiring persistent power to ensure that there isn't a meltdown or explosion is monumentally dumb. When power is cut, the nuclear reactor should have fail safe mechanisms to cool the core down for a duration needed to reach safe temperatures. Requiring mechanical pumps that use power to do so and are prone to hiccups is a death sentence. What should be required is a water tower that stores water at elevation. It would be connected to the cooling system of the core but would be held back by solenoid values that require power to stay closed. When the power goes out, the solenoid valves open and the water from the water tower pours in to cool the reactor. The valves are sized so that a persistent rate of flow is obtained for the time needed. THIS IS WHAT IT MEANS TO BE FAIL SAFE.

Yes, because pouring a large amount of cold water on a nuclear pile is a good idea.

What do you think they've been doing to the nuke piles right now? Hint: Water. And you don't pour directly on, it goes through the cooling tubes so it doesn't make direct contact, duh.

Unless it's a swimming pool reactor, 'foon.

[Svartalf]

I don't know what kind of idiots design nuclear power plants, but requiring persistent power to ensure that there isn't a meltdown or explosion is monumentally dumb. When power is cut, the nuclear reactor should have fail safe mechanisms to cool the core down for a duration needed to reach safe temperatures. Requiring mechanical pumps that use power to do so and are prone to hiccups is a death sentence. What should be required is a water tower that stores water at elevation. It would be connected to the cooling system of the core but would be held back by solenoid values that require power to stay closed. When the power goes out, the solenoid valves open and the water from the water tower pours in to cool the reactor. The valves are sized so that a persistent rate of flow is obtained for the time needed. THIS IS WHAT IT MEANS TO BE FAIL SAFE.

Yes, because pouring a large amount of cold water on a nuclear pile is a good idea.

What do you think they've been doing to the nuke piles right now? Hint: Water. And you don't pour directly on, it goes through the cooling tubes so it doesn't make direct contact, duh.

Nop, what they are doing is to make the pumps of the first stage cooling system work, so the water heated by the core can be cooled by being put next to cold water, and the cooled water pumped next to the core so as to lower its temperature... you don't want to brutally reduce and atomic core's temperature, lest the shell suffer and get leaks.

[JOZeldenrust]

The explosion was most probably in the cooling system, a hydrogen-oxygen reaction.

Where would the unreacted hydrogen and oxygen come from?

Most likely the explosion was the result of steam overpressurization of the secondary containment building. Keeping the core cooled during the residual heat period involves letting it boil water, and likely the resulting steam was escaping into the secondary containment. A cubical structure, as the secondary containment was here, wouldn't be able to withstand much internal pressure.

It wasn't a nuclear explosion as happened at Chernobyl. However, we should expect substantial radiation release now - not as much as Chernobyl, perhaps, but still a lot more than all other nuclear accidents combined.

What the fuck do you mean by "unreacted", please?

I mean not already in the form of water. Water doesn't burn.

It's possible that the cooling water underwent thermal decomposition, though that would require temperatures of around 3000 degrees C, and it seems unlikely that such temperatures were reached. It's also possible that the explosion wasn't caused by anything burning, but by the container of the pressurized steam collapsing.

I understand that efforts are being made to flood the core with Boron, which will capture neutrons, partly taking over the role of the control rods. Those are most likely made of some metal or alloy that might melt and leak out of the core. The Boron will prevent the core from going into cascade meltdown should that happen. Still, there are a lot of uncertainties. News has been scarse, I might well have misinterpreted what I've seen and heard, and even if this is the current situation, the Boron might not have the desired effect. Even if it has, large quantities of radioactive material may still be released into the environment.

[Geoff]

http://www.reuters.com/article/2011/03/ ... UN20110312

The Japanese nuclear safety agency rated the damage at a nuclear power plant at Fukushima at a four on a scale of one to seven, which is not quite as bad as the Three Mile Island accident in the United States in 1979, which registered a five.

Actually, that's misleading, as it's a logarithmic scale.

[Gawdzilla Sama]

http://www.reuters.com/article/2011/03/ ... UN20110312

The Japanese nuclear safety agency rated the damage at a nuclear power plant at Fukushima at a four on a scale of one to seven, which is not quite as bad as the Three Mile Island accident in the United States in 1979, which registered a five.

Actually, that's misleading, as it's a logarithmic scale.

And, of course, no radiation leaked into the atmosphere at TMI, so the may, as usual, be overplayed.

[JimC]

The explosion was most probably in the cooling system, a hydrogen-oxygen reaction.

Where would the unreacted hydrogen and oxygen come from?

Most likely the explosion was the result of steam overpressurization of the secondary containment building. Keeping the core cooled during the residual heat period involves letting it boil water, and likely the resulting steam was escaping into the secondary containment. A cubical structure, as the secondary containment was here, wouldn't be able to withstand much internal pressure.

It wasn't a nuclear explosion as happened at Chernobyl. However, we should expect substantial radiation release now - not as much as Chernobyl, perhaps, but still a lot more than all other nuclear accidents combined.

I think this is a fairly likely scenario. I suspect the radiation involved would mostly come from the tritium (a Beta -ve emitter) that a certain % of the hydrogen nuclei will have been converted into by prolonged neutron bombardment.

On a note of irony, my Year 11 Physics class have an important assessment task this Tuesday.

They are to write an essay on the advantages and disadvantages of generating power from nuclear reactors. I think there is another paragraph or two that they can add at this point...

[Gawdzilla Sama]

On a note of irony, my Year 11 Physics class have an important assessment task this Tuesday.

They are to write an essay on the advantages and disadvantages of generating power from nuclear reactors. I think there is another paragraph or two that they can add at this point...

Jim, show them this picture. Ask them what the significance of the valley to the left is.



(Clue: It's a fault line. San Onofre Nuclear Power Generating Station, just south of LA.)

[Tero]

I think this is a fairly likely scenario. I suspect the radiation involved would mostly come from the tritium (a Beta -ve emitter) that a certain % of the hydrogen nuclei will have been converted into by prolonged neutron bombardment.

On a note of irony, my Year 11 Physics class have an important assessment task this Tuesday.

They are to write an essay on the advantages and disadvantages of generating power from nuclear reactors. I think there is another paragraph or two that they can add at this point...

Thanks Jim for some sense into this confusion I am reading above. Hydrogen , oxygen.

Water:
http://en.wikipedia.org/wiki/Boiling_water_reactor

[Warren Dew]

I don't know what kind of idiots design nuclear power plants, but requiring persistent power to ensure that there isn't a meltdown or explosion is monumentally dumb. When power is cut, the nuclear reactor should have fail safe mechanisms to cool the core down for a duration needed to reach safe temperatures. Requiring mechanical pumps that use power to do so and are prone to hiccups is a death sentence. What should be required is a water tower that stores water at elevation. It would be connected to the cooling system of the core but would be held back by solenoid values that require power to stay closed. When the power goes out, the solenoid valves open and the water from the water tower pours in to cool the reactor. The valves are sized so that a persistent rate of flow is obtained for the time needed. THIS IS WHAT IT MEANS TO BE FAIL SAFE.

Nuclear power plants generate a considerable amount of residual heat - initially several percent of their operating power level - for days after they are shut down. Passive cooling methods are simply not adequate for most commercial nuclear plants. It might be possible to design plants around that requirement, but they might well be uneconomically expensive.

My first question would be, why did the diesel generators go offline an hour after the shutdown, and why weren't they restarted? The other units at the site appear to have been fine. Why weren't there backup diesels, or a way to get power from the diesels at the other units?

http://www.reuters.com/article/2011/03/ ... UN20110312

The Japanese nuclear safety agency rated the damage at a nuclear power plant at Fukushima at a four on a scale of one to seven, which is not quite as bad as the Three Mile Island accident in the United States in 1979, which registered a five.

Actually, that's misleading, as it's a logarithmic scale.

It's misleading, because it's a flat out lie.

Neither primary nor secondary containment were ever breached at Three Mile Island. No one was exposed to dangerous levels of radioactivity. Radiation levels outside the containment were normal.

At Fukushima, in contrast, radioactivity levels were high outside the containment, and 1000 times normal in the control room, well before the explosion. With the explosion, secondary containment has not only been breached - it's been eliminated. Now, huge amounts of radioactive steam are being released, likely with substantal amounts of fission products, not just tritium, in it.

On a scale where Three Mile Island is a 5, and Chernobyl is a 7 - lots of people died from Chernobyl - Fukushima is at least a 6.

[Tero]

http://en.wikipedia.org/wiki/Fukushima_ ... ower_Plant

Potentially radioactive steam was released from the primary circuit into the secondary containment area to reduce mounting pressure

steam, a type of water

radioactive caesium-137 was detected near reactor...
Caesium-137 (137
55Cs, Cs-137) is a radioactive isotope of caesium which is formed mainly as a fission product by nuclear fission.