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The nuclear fission does not work

  1. Apr 22, 2008 #1
    The nuclear fission does not work!!!

    No infraction please!!!

    I was perhaps mistakenly under the impression that matter was destroyed in nuclear
    fission, but a careful look at this diagram (top right) appears to show all the
    protons, neutrons and electrons are balanced in the equation.
    So our current nuclear power stations would appear to be running on 'hot air' or
    scientific bullsh*t?

    Can someone please explain what I am missing? (other than a brain).
  2. jcsd
  3. Apr 22, 2008 #2
    The re-arragement of neutrons and protons into smaller nuclei does release energy as our plants do work. Some mass do disappear indeed. The thing that you miss is that the mass of the nucleus is not the sum of the mass of the protons and neutrons composing it. The binding energy accounts for the difference.

    This is elementary nuclear physics and is well understood for decades now.
  4. Apr 22, 2008 #3
    But the mass of the nucleus *is* the sum of the mass of the protons and neutrons (and electrons) composing it, surely?? Energy does not have a mass, because well it is
    energy, not mass.

    I can accept that the binding energy, releases the energy in a nuclear reaction, however
    no destruction of mass would be involved, just binding energy converted into other
    forms of energy as ain a chemical reaction where similarly no mass is lost.

    Yes I can accept binding energy is released, but there is mo 'missing' mass, all the
    electrons protons and neutrons are still there, I have counted them :O)

    And as far as I am aware, all electrons weigh the same, same goes for protons and neutrons.

    So where is the mass which disappears? There is no disappearing mass, just 'disappearing'
    binding energy.
  5. Apr 23, 2008 #4
    OK going back on your explaination now that I have read more:-
    "the mass of the nucleus is not the sum of the mass of the protons and neutrons composing it" is a little unclear, it seems the 'mass' of a particle depends on it's
    relationship with other particles.

    Also to say for example a Uranium atom contains 92 protons depends to certain extent
    what you mean my a proton. Might be more accuracte to say it contains 91.9934 (or whatever) protons, and some binding energy?

    I am not a nuclear physicist by the way (I am sure your will be relieved to hear that!!!)
    Last edited: Apr 23, 2008
  6. Apr 23, 2008 #5


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    esbo, have you ever heard of the forumula: [itex] E = mc^2 [/itex]

    ?.. :)

    Probably the most famous physics formula out there.

    So yes, the mass of a particle depends on several things, one of them is in bound systems its mass decreases. And when it is moving in very high speeds - it mass increases (just as einstein has predicted aswell).

    I mean it is so easy, you have 92 building blocks which bare masses are 1mass unit, then the composite system has a mass of 91.5 mass units, then what the heck happened to the missing 0.5mass unit?! Well it was converted into bidning energy, which holds all the 92 particles together.

    In a nuclear fission plant, one releases a lot of binding energy, which is converted into kinetic energy of the fission fragments. The fission fragments will bounch of on the water in the reactor -> heating it up (since Temperature is equal to the mean kinetic energy of a substance)

    Nuclear fission in a nutshell
    Last edited: Apr 23, 2008
  7. Apr 23, 2008 #6
    An additional factoid esbo might be interested to know if he comes back here: Iron has the lowest binding energy of all elements. Thus, it is the most stable. Smaller nuclei release energy if fused to make heavier nuclei; heavier nuclei release energy when split - until you get to iron. Cannot fuse or fracture iron to release energy.
  8. Apr 23, 2008 #7


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    and by lowest you mean 'most negative'

    also i think it is Ni-58 who has most BE/nucleon ...
  9. Apr 23, 2008 #8
    I did read (somewhere) not too long ago that iron was the most stable element(nucleus), actually.
    You might expect by that that iron thus would be the most abundant on earth (prehaps).
    It's not apparently, it's oxygen, but I guess there are reasons for that? (by definition).

    Anyway it seems I have, I have learned something, I did not realise that protons lost mass when they bound, however maybe that explains why you can stick the buggers
    togeather, since they have repelling charges? (always puzzled me).

    I presume they discovered E=MC2 when elements did not weigh as much as they should??
    (compared to the masses of electrons and protons unbinded?).

    I guess you might say the mass of a proton is 'variable'?

    Also do neutron every vary in 'mass'?
  10. Apr 23, 2008 #9


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    1) E = mc^2 is derived from theory...

    2) You have in a nucleus a compeating force wich is attractive but short range that compensates for the repulsive electro-force. This attrative force is between both neutrons and protons, neutrons and neutrons, & protons and protons. That is why only certain combinations of protons and neutrons form a stable nucleus.

    3) Nope, most stable element is: Ni-62 (not 58 as i thought;) )
    But why iron is quite more abundant than nickel has to do with the properties of stellar burning...

    Now since you did not had any knowledge about nuclear physics, how can you call anything "scientific b***it" ??
  11. Apr 23, 2008 #10
    Yes I think I was reading/watching something about the formation of elements in stars
    where it said iron was the most abundant element in the universe (but not on earth apparently as I assumed). I didn't say nuclear physics was bullsh*t, it just appeared that way because I had never had it fully expalined to me.
  12. Apr 23, 2008 #11


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    Iron is not the most abundant element in the universe either.. hydrogen is, followed by helium.
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