Just in case other people were wondering about Fukushima

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Elan Tedronai

Senior Member

03-29-2011

This has been tickling the back of my mind ever since the incident. I don't watch the news so my apologies if this if common knowledge.

Quote:
Why still heating after shutdown?
We may logically ask why, if the reactors are shut down, does the fuel continue to generate heat and, actually increase in temperature to several thousand degrees F with no coolant water flow? When the reactor shuts down, doesn’t all fission in the core cease – thus no more heat is generated? The answer is no.

The effect is known as decay heat. Throughout the reactor fuel cycle lifetime, as the Uranium atoms break apart, they give off lots of usable energy. After fission, the broken pieces of the U atom are now smaller, and have become other elements such as Iodine and Strontium. These are called fission products, and some of these smaller atoms are radioactive themselves. Some of them emit neutrons along with other radiations. These emitted neutrons can still hit other Uraniums and cause the U atoms to fission and release heat, even though the reactor is turned off. So heat continues to build up in the core even after the reactor is shut down. (Decay heating.) If the reactor has operated for a long time, lots of fission products have built up in the fuel rods, causing much decay heat generation. The fuel then stays hot unless cooled by circulating water.


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Lemons

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Senior Member

03-29-2011

The whole situation is pretty ****ed. They are using sea water to cool the rods, but the salt in the water can crust up and block the water from really cooling the rods. Which will cause the rods to rupture and release radiation.


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Postal Twinkie

Wrenchman

03-29-2011

Quote:
Originally Posted by Lemons View Post
The whole situation is pretty ****ed. They are using sea water to cool the rods, but the salt in the water can crust up and block the water from really cooling the rods. Which will cause the rods to rupture and release radiation.
They stopped using sea water about two days ago and started using fresh water. The length of time they used sea water wasn't enough to cause irreversible deposit buildup, and it should flush out.


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Lemons

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Senior Member

03-29-2011

Quote:
Originally Posted by Postal Twinkie View Post
They stopped using sea water about two days ago and started using fresh water. The length of time they used sea water wasn't enough to cause irreversible deposit buildup, and it should flush out.
Oh good. Right now they're just cooling it with water, but I wonder how long it'll take until they'll secure it.


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Wrenchman

03-29-2011

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Originally Posted by Lemons View Post
Oh good. Right now they're just cooling it with water, but I wonder how long it'll take until they'll secure it.
The main issue is getting the reactor to a point where they can remove the fuel rods, mainly in reactor number 3. The big issue as to why they can't do it now is the robots used for removing the fuel rods were damaged. The reactor itself is also too **** dangerous to have someone go in. Basically they get to babysit the rods until the environment reaches a point they can safely remove them manually, or they can get robots in place to remove them.


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Hamsamwich

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Senior Member

03-29-2011

I feel like America could be helping more.... Instead of investing in another war....

I hope America turns into an Oroson Scott Card America.. They are so passive and rich.


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Wrenchman

03-29-2011

Quote:
Originally Posted by Hamsamwich View Post
I feel like America could be helping more.... Instead of investing in another war....

I hope America turns into an Oroson Scott Card America.. They are so passive and rich.
We offered help, and are helping. However our help is limited to what the Japanese government will allow us to provide. Now is what we offered greater than what they will allow us? I doubt it....

I would rather see the money we are spending on war go to help other countries in need, like the current situation in Japan.


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Elan Tedronai

Senior Member

03-30-2011

It's so unfortunate that this situation has tarnished the safety record of nuclear power. Nuclear power is quite safe and actually quite harmless. When plants are operating safely you get more radiation exposure living next to a coal fired plant than a nuclear plant. It is my understanding that this plant is an older design and that modern designs alleviate this issue?

In my mind, nuclear power is still incredibly safe, we just can't be dimwitted about where we put them. Japan's Pacific cost? Bad idea. California coast? Bad idea. BFE, Nebraska? Good idea. I realize they need put where the power is needed but some solutions just aren't worth the risk.