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Thread: Help resolving a nuclear power debate

  1. #1 Help resolving a nuclear power debate 
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    Hi,

    The problem i am faced with is this:

    A friend firmly states that advances in nuclear energy and modern nuclear power stations produce much less "hazardous waste" than they used to; Also that this waste is treated so that it is returned to non-hazardous radiation levels in a much faster time than it used to. This removes the problem of the waste created.

    I argue against this saying that as far as i was aware (and i may well be wrong) that the nuclear decay of a radioactive nucleus is impossible to predict or to affect. So the waste will still be around for a long time (i was reconing ~10,000 years, but this is a total guess) as the halflife of the fuel (i was thinking uranium was used, again i have no real knowledge though) is an inherent property of this element.

    Which of us is wrong here? And are there any studies that back up either side?

    Many thanks in your help.

    Jim


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  3. #2  
    Forum Professor Wild Cobra's Avatar
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    I am by no means very well versed in this aspect of science. However, I do know this. There are different reactor designs that do use different concentrations and enrichment of uranium. This alone changes how the resultion collisions changes other atoms.

    I will venture to say that your friend is probably correct, but only to a minor degree. I kind of doubt the "much faster" aspect of it, but I will not rule it out.


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  4. #3  
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    Part of the solution is an engineering problem in that the waste can be processed to separate the highly radioactive short lived nuclides from the less radioactive long lived. The short lived can be set aside to decay, while the long life stuff (mostly uranium and plutonium) can to some extent be recycled as reactor fuel.
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  5. #4  
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    I suspect your friend may have been thinking of the thorium cycle.
    http://en.wikipedia.org/wiki/Thorium_fuel_cycle

    But there really aren't any of those around that I know of.

    Or possibly he was referring to reprocessing, which does reduce the long term radioactivity of the waste.
    http://en.wikipedia.org/wiki/Nuclear_reprocessing
    Most radioactivity in roughly 102~105 years after fuel use is produced by actinides, since there are no fission products with half-lives in this range. These actinides can fuel fast reactors, so extracting and reusing (fissioning) them reduces the long-term radioactivity of the waste and reduces fuel needs.
    http://www.princeton.edu/sgs/publica...ev293n5539.pdf
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  6. #5 Re: Help resolving a nuclear power debate 
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    advances in nuclear energy and modern nuclear power stations produce much less "hazardous waste" than they used to
    Ironically the industry has "progressed" to more less-efficient plants. CANDU (Canadian) reactors conceived in the early 50's are still the most efficient in terms of electricity generated per unit of fuel, moreover they can effectively burn natural unprocessed uranium, or old weapon material including plutonium, or the depleted uranium waste of other crappier designs. Political interests of ambitious nuclear states (France, USA, Russia) exercise clout to push their own (crappy) designs ahead of CANDU.


    Decay rate of waste is easy to predict. It's just the decay of any single atom that is random. Anyway it takes about 500 years before the waste returns to toxicity comparable with natural uranium or lead ore, if particles enter groundwater. On the other hand this stuff even "hot out of the oven" is harmless beneath 3 meters of water, in a storage pool.
    A pong by any other name is still a pong. -williampinn
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  7. #6  
    Forum Bachelors Degree Waveman28's Avatar
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    Nuclear fission is a bad source of energy. It requires mining and excavation, which has many disasterous effects on landscape. It is inefficient and produces waste which is costly and hazardous. The future will certainly not rely on it, so you are wise to be against it.
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  8. #7  
    Forum Radioactive Isotope MagiMaster's Avatar
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    Just have to add my 2 cents here, but how is coal any better than that?
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  9. #8  
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    Quote Originally Posted by Background_noise
    ....produce much less "hazardous waste" than they used to;
    There is no reason to say that your friend is wrong here. With the advancement of technology, reactors would obviously become more efficient at using the energy they have to produce less waste.

    Quote Originally Posted by Background_noise
    this waste is treated so that it is returned to non-hazardous radiation levels in a much faster time than it used to.
    Wrong. There is no possible way to speed up or slow down the decay of radioactive materials. Every radioactive substance has a half-life that cannot be changed by any means (changing temperature, changing pressure, etc.).

    For example: U-235 has a half-life of 703,800,000 years. You simply can't make that number change to lets say....1,000 or 10 years by any physical means.

    With that said, this statement
    Quote Originally Posted by Background_noise
    This removes the problem of the waste created.
    is not true. When it comes to nuclear fission, our conventional methods of using this energy will always produce waste....just like hydrocarbon vehicles will always produce CO gas.
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  10. #9  
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    Quote Originally Posted by Reaper
    Wrong. There is no possible way to speed up or slow down the decay of radioactive materials.
    Not exactly true. Plutonium-239 with a half-life of 24,000 years is toxic and one of the main reasons that nuclear waste remains hazardous for a long time. It is also fissile. After it undergoes fission, it is no longer plutonium-239.

    For example: U-235 has a half-life of 703,800,000 years. You simply can't make that number change to lets say....1,000 or 10 years by any physical means.
    Why do people keep mentioning U-235? That is not a by-product of nuclear fission. It's the fuel in the ore that is already in the earth. It is actually being used up by the fission process.
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  11. #10  
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    Quote Originally Posted by Reaper

    For example: U-235 has a half-life of 703,800,000 years. You simply can't make that number change to lets say....1,000 or 10 years by any physical means.
    Sure you can.

    How do you think a fission bomb works ?

    Or, what bout the moderation of fission reactions in any ordinary nuclear reactor ?
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  12. #11  
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    I think reaper is referring to the fact that you cant change it for that particular element. Although you can reduce the half life of the material by fission, the material is no longer U-235.
    'Aint no thing like a chicken wing'
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  13. #12  
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    Quote Originally Posted by DrRocket
    Quote Originally Posted by Reaper

    For example: U-235 has a half-life of 703,800,000 years. You simply can't make that number change to lets say....1,000 or 10 years by any physical means.
    Sure you can.

    How do you think a fission bomb works ?

    Or, what bout the moderation of fission reactions in any ordinary nuclear reactor ?
    I'm talking about the rate of decay. Take a piece of radioactive waste and you cannot in any way change how fast it'll decay before its safe enough to handle. Background_noise is making the notion that it's possible to

    Quote Originally Posted by Background_noise
    treated so that it is returned to non-hazardous radiation levels in a much faster time than it used to.
    This is why nuclear waste is a problem. Every time you produce waste, you have to store it somewhere away from society because it takes billions of years before its no longer radioactive.
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  14. #13  
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    Quote Originally Posted by Reaper
    Quote Originally Posted by DrRocket
    Quote Originally Posted by Reaper

    For example: U-235 has a half-life of 703,800,000 years. You simply can't make that number change to lets say....1,000 or 10 years by any physical means.
    Sure you can.

    How do you think a fission bomb works ?

    Or, what bout the moderation of fission reactions in any ordinary nuclear reactor ?
    I'm talking about the rate of decay. Take a piece of radioactive waste and you cannot in any way change how fast it'll decay before its safe enough to handle.
    If the uranium is no longer uranium, then it no longer has the same half-life.

    This is why nuclear waste is a problem. Every time you produce waste, you have to store it somewhere away from society because it takes billions of years before its no longer radioactive.
    You do understand that there is naturally occurring radioactive material don't you?
    If the waste decays to the level of the ore that it was mined from, would that satisfy you, or does it have to be completely gone?
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  15. #14  
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    Quote Originally Posted by Harold14370
    You do understand that there is naturally occurring radioactive material don't you?
    If the waste decays to the level of the ore that it was mined from, would that satisfy you, or does it have to be completely gone?
    Apparently not, as uranium mine tailings upset some people.
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