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Thread: THE ATOM BOMB ?

  1. #1 THE ATOM BOMB ? 
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    Hi guys,

    is splitting the atom anything to do with the production of the atom bomb ?

    Are modern nuclear bombs still atom bombs ?

    BARCUD


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  3. #2 Re: THE ATOM BOMB ? 
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    Quote Originally Posted by BARCUD
    Hi guys,

    is splitting the atom anything to do with the production of the atom bomb ?

    Are modern nuclear bombs still atom bombs ?

    BARCUD
    The original A-bombs worked by a process called fission. It works like this:

    Certain isotopes of certain elements can spontaneously "break apart" into smaller parts forming lighter elements releasing energy, this is called spontaneous fission. It doesn't happen very often, so in any sample of this given element you will only have a few atoms doing it at any time.

    When the isotopes undergo fission they release stray neutrons. Those neutrons can then strike other atoms and cause them to break apart and undergo nuclear fission. These atoms in turn emit neutrons, Etc.

    Now, in a usual sample of Uranium you are going to have both U-238 and U-235. Only U-325 will undergo fusion. Most uranium is U-238. Thus the vast majority of Neutrons emitted by the few fissioning U-235 atoms, never hit another U-235 atom.

    But if you separate the U-235 away from the U-238 (a process called enrichment). You can make a mass that is mostly U-235. And if that mass is large enough (greater than what is called "critical mass"), you can get a chain-reaction. Where neutrons produced by spontaneous fission cause nuclear fission in other atoms, and the netrons released from that causes fission in other atoms...

    You end up with a lot of atoms undergoing fission all at once and a quick explosive release of energy.

    A-bombs generally work by suddenly bringing smaller pieces of an enriched fissionable element together into one critical mass.


    There is nuclear process that releases energy called fusion. If you take hydrogen atoms and force them together hard enough, they will fuse together and form a helium atom and release energy in the process. This is the opposite of the fission process. The difference is that while large heavy atoms will give off energy when broken apart. Small light atoms do so when fused together (this has to do with the binding energies needed to hold these atoms together.

    One extra point: Just like fission, certain isotopes of hydrogen fuse better than others, so we separate this isotope out.

    H-bombs use fusion. They are more powerful than A-bombs because, 1) The fusion process releases more energy than the fission process. and 2) There is a limit as to how much fissionable material you can push together fast enough to get it all to under-go fission before it is blown apart.

    The trick with an H-bomb is to force the Hydrogen together with enough energy. They do this by using an A-bomb as the trigger. So an H-bomb is an A-bomb trigger surrounded by a shell of fusable hydrogen. The a-bomb goes off, providing the energy to fuse the hydrogen into helium which in turn releases even greater amounts of energy.


    "Men are apt to mistake the strength of their feelings for the strength of their argument.
    The heated mind resents the chill touch & relentless scrutiny of logic"-W.E. Gladstone


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  4. #3  
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    Wow, sounds straight forward to me but there must have been one heck of a lot of theorising and experimenting to get these results !

    If there wasn't a drive to build 'the bomb' would these things have remained unknown ? Or would the drive for alternative energy produced the same findings ?

    BARCUD
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  5. #4  
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    Quote Originally Posted by BARCUD
    Wow, sounds straight forward to me but there must have been one heck of a lot of theorising and experimenting to get these results !
    Definitely. That's what the whole Manhattan project was about. The problems were huge. Could a chain reaction actually be maintained? How do you enrich Uranium considering that the isotopes are chemically identical. How do you bring the separate pieces of Uranium together so that they fission explosively and the reaction doesn't fizzle out. Many of the greatest minds in physics were brought together to solve these problems.

    If there wasn't a drive to build 'the bomb' would these things have remained unknown ? Or would the drive for alternative energy produced the same findings ?

    BARCUD
    The idea of "atomic" power or weapons dates back as far back as 1914. Many science fiction writers wrote about it. For example, Robert Heinlein wrote a story, Solution Unsatisfactory in 1940 about a "Cold War" caused by the use of radioactive dust. Lester Del Rey wrote Nerves a story about an accident at an atomic power plant in 1942, before the first nuclear pile went into operation. The FBI actually investigated some SF authors because they wrote details about atomic bombs that were very close to what the Manhattan Project was working on.
    "Men are apt to mistake the strength of their feelings for the strength of their argument.
    The heated mind resents the chill touch & relentless scrutiny of logic"-W.E. Gladstone


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