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Thread: Nuclear Explosion

  1. #21
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    Default Re: Nuclear Explosion

    chernobyl used positive feedback systems (potential to get unstable, which it did)

    There wun be any mushrooms because it wun explode. All the nuclear reactor does is to boil water like a kettle and drive the turbines which produces the electricity.

    Since there's no 'detonator' to amount to a critical mass, all you get is a critical mess after that.
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  2. #22
    Senior Member Hommie's Avatar
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    Default Re: Nuclear Explosion

    I have got it! More powerful than nuclear fission is nuclear fusion. Instead of splitting atoms' nucleus splits into two or more smaller nuclei plus some by-products, fusion is a process in which two nuclei join, forming a larger nucleus and releasing or absorbing energy.

    The fusion of lighter nuclei, which creates a heavier nucleus and a free neutron, will generally release even more energy than it took to force them together. The energy released in most nuclear reactions is much larger than that for chemical reactions, because the binding energy that glues a nucleus together is far greater than the energy that holds electrons to a nucleus.

    hydrogen bomb is one such example.

  3. #23
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    Default Re: Nuclear Explosion

    Quote Originally Posted by Hommie
    I have got it! More powerful than nuclear fission is nuclear fusion. Instead of splitting atoms' nucleus splits into two or more smaller nuclei plus some by-products, fusion is a process in which two nuclei join, forming a larger nucleus and releasing or absorbing energy.

    The fusion of lighter nuclei, which creates a heavier nucleus and a free neutron, will generally release even more energy than it took to force them together. The energy released in most nuclear reactions is much larger than that for chemical reactions, because the binding energy that glues a nucleus together is far greater than the energy that holds electrons to a nucleus.

    hydrogen bomb is one such example.
    I see you've done your homework. Now don't go and build one ok

  4. #24

    Default Re: Nuclear Explosion

    Apologies for the long reply

    Cirtical mass is the mass of "fuel" required for fission/fusion to take place (which means plants already have critical mass, else there will be no reaction)

    In the first place, do you know what is the mushroom cloud? It's caused by sudden and rapid increase tempreature above ground (thereby expansion and rising of air), then followed by the in-rush of air to fill in the vaccum.

    There are some difference between those in warheads and those used in plants (nuclear plants/ships/subs).

    Firstly, it's the difference is grade of nuclear fuel used, weapon grade is much more pure.

    Secondly, the reaction in plants are controlled by neutron rods.

    So in the case of an unlikely plant "accident" it should not have the mushroom cloud as the neuclear reaction is contained and you'll get radiation leaks and at worst a total plant melt-down. Also, before a run-away reaction can take place, most likely the automatic crash-stop procedure to insert all neutron rods into the reaction chamber should already be executed.

    Even if a N-strike on a N-plant, the plant also unlikely to go the same way of the N-bomb as mentioned above different grade of fuel is used as well as N-bomb are likely to detnotate about 1KM above surface, thus by the time the blast effect hit the reaction chamber the condition is already not suitable for N-reaction.

    BTW, understand that a total run-away meltdown of a n-plant is more dangerous than a N-bomb explosion, cuz the reaction is soo hot that it will burn right through into the earth's core. So far all meltdown are prevented from a total run-away.
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  5. #25
    Senior Member Hommie's Avatar
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    Default Re: Nuclear Explosion

    Quote Originally Posted by CYRN
    Apologies for the long reply

    Cirtical mass is the mass of "fuel" required for fission/fusion to take place (which means plants already have critical mass, else there will be no reaction)

    In the first place, do you know what is the mushroom cloud? It's caused by sudden and rapid increase tempreature above ground (thereby expansion and rising of air), then followed by the in-rush of air to fill in the vaccum.
    Hey thanks for enlightening me!

    I guess most understood me when I mentioned in the first post as 'mushroom-like explosion' meaning that possibility of whether the scale of the explosion will reach as one with a intention to a nuclear bomb. I think I didn't phrase my question properly, my bad!

    I think you are wrong on the critical mass portion. Critical mass refers to the chain-reaction to form a massive explosion. If we split one single atom by bombarding the nucleus of a fissile atom with another particle of the correct energy, making the nucleus unstable. The unstable nucleus will then split into two or more pieces. These pieces are known as fission products and include two smaller nuclei, two or three other free neutrons, and some photons. The process releases a lot of energy compared to chemical reactions; the energy is released in the form of both photon radiation (like gamma rays) and in the kinetic energy (energy of motion) of the nuclei and neutrons.

    Energy is release as such but to create a bomb base on the energy, chain-reaction will be needed. Below is take from http://en.wikipedia.org/wiki/Nuclear_fission

    Critical mass

    When fission events occur in a mass of uranium (or other fissile material), neutrons are released. Some of these neutrons are captured by other uranium nuclei and lead to fission; some will escape the mass or be absorbed by some other kind of nucleus. If the expected number of neutrons which trigger new fissions is less than one, a nuclear chain reaction may occur but the size will decrease exponentially. If the expected number of neutrons is greater than one, the chain reaction will increase exponentially. This situation (expected number of neutrons causing fission is one or more) is called criticality, and the configuration is called a critical mass.

    While any critical mass will in principle lead to exponential growth, the time this will take depends on several factors. The degree to which the mass is supercritical affects the rate of growth. However, as mentioned above, a fraction of the neutrons that cause fission do so only after a brief delay. This delay slows the process of exponential growth and permits the control of nuclear chain reactions. If there are enough neutrons captured so that the ones causing immediate fission are sufficient to lead to exponential growth, then the mass is called prompt critical and it becomes very difficult to control.

    A simple nuclear weapon relies on this exponential growth to induce fission in a significant fraction of the fissile nuclei it contains. Such a device must not only be prompt critical, it must be highly prompt critical. Moreover, it must be rapidly converted from a subcritical configuration (for storage) to a highly prompt critical configuration upon detonation. This is a difficult procedure.

  6. #26

    Default Re: Nuclear Explosion

    You can build your own Nuclear reactor at home. Read the story of the Radioactive Boy Scout
    Last edited by reno77; 15th August 2005 at 08:07 PM.

  7. #27

    Default Re: Nuclear Explosion

    Quote Originally Posted by Hommie
    Hey thanks for enlightening me!

    I guess most understood me when I mentioned in the first post as 'mushroom-like explosion' meaning that possibility of whether the scale of the explosion will reach as one with a intention to a nuclear bomb. I think I didn't phrase my question properly, my bad!

    I think you are wrong on the critical mass portion. Critical mass refers to the chain-reaction to form a massive explosion. If we split one single atom by bombarding the nucleus of a fissile atom with another particle of the correct energy, making the nucleus unstable. The unstable nucleus will then split into two or more pieces. These pieces are known as fission products and include two smaller nuclei, two or three other free neutrons, and some photons. The process releases a lot of energy compared to chemical reactions; the energy is released in the form of both photon radiation (like gamma rays) and in the kinetic energy (energy of motion) of the nuclei and neutrons.

    Energy is release as such but to create a bomb base on the energy, chain-reaction will be needed. Below is take from http://en.wikipedia.org/wiki/Nuclear_fission

    Critical mass

    When fission events occur in a mass of uranium (or other fissile material), neutrons are released. Some of these neutrons are captured by other uranium nuclei and lead to fission; some will escape the mass or be absorbed by some other kind of nucleus. If the expected number of neutrons which trigger new fissions is less than one, a nuclear chain reaction may occur but the size will decrease exponentially. If the expected number of neutrons is greater than one, the chain reaction will increase exponentially. This situation (expected number of neutrons causing fission is one or more) is called criticality, and the configuration is called a critical mass.

    While any critical mass will in principle lead to exponential growth, the time this will take depends on several factors. The degree to which the mass is supercritical affects the rate of growth. However, as mentioned above, a fraction of the neutrons that cause fission do so only after a brief delay. This delay slows the process of exponential growth and permits the control of nuclear chain reactions. If there are enough neutrons captured so that the ones causing immediate fission are sufficient to lead to exponential growth, then the mass is called prompt critical and it becomes very difficult to control.

    A simple nuclear weapon relies on this exponential growth to induce fission in a significant fraction of the fissile nuclei it contains. Such a device must not only be prompt critical, it must be highly prompt critical. Moreover, it must be rapidly converted from a subcritical configuration (for storage) to a highly prompt critical configuration upon detonation. This is a difficult procedure.
    yeah lah... you read your own quote properly leh

    summarised to mean the minimum mass of fuel required to sustain a nuclear reaction...else will be like lighting a match stick, where the reaction will juz fizzle out "exponentially" due to the absorbtion of neutrons.
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  8. #28

    Default Re: Nuclear Explosion

    Quote Originally Posted by Hommie
    Hey thanks for enlightening me!

    I guess most understood me when I mentioned in the first post as 'mushroom-like explosion' meaning that possibility of whether the scale of the explosion will reach as one with a intention to a nuclear bomb. I think I didn't phrase my question properly, my bad!
    tot someone already answered this earlier... N-explosion is measured in "Tons of TNT"... ie a 5 Megaton bomb would have the equivilant power of 5 Megatons of TNT. So, if sufficient large amount of conventional explosion at the correct attitude would also cause the mushroom cloud.
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  9. #29
    Senior Member Hommie's Avatar
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    Default Re: Nuclear Explosion

    Quote Originally Posted by CYRN
    yeah lah... you read your own quote properly leh

    summarised to mean the minimum mass of fuel required to sustain a nuclear reaction...else will be like lighting a match stick, where the reaction will juz fizzle out "exponentially" due to the absorbtion of neutrons.
    More like timing and mass. If the timing was out from the denotation then the explosion will lose steam and fizzle.

  10. #30

    Default Re: Nuclear Explosion

    You can also build your own crude fusion reactor.. not a practical one though as the power input is more than the output.

    http://www.fusor.us/fusor.html
    http://deseretnews.com/dn/view/0,1249,510054502,00.html
    Last edited by reno77; 15th August 2005 at 08:47 PM.

  11. #31

    Default Re: Nuclear Explosion

    Quote Originally Posted by Hommie
    More like timing and mass. If the timing was out from the denotation then the explosion will lose steam and fizzle.
    yeah... but timing is not part of the defination of critical mass loh.
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  12. #32
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    Default Re: Nuclear Explosion

    Remind me not to piss you off
    Time, is an effortless construction :)

  13. #33

    Default Re: Nuclear Explosion

    Quote Originally Posted by Pablo
    Remind me not to piss you off
    you'll end up looking like his avatar
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  14. #34
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    Default Re: Nuclear Explosion

    Quote Originally Posted by CYRN
    yeah... but timing is not part of the defination of critical mass loh.
    Not completely true as Critical Mass is a result of chain-reaction and timing is everything to achieve the chain-reaction to form the Critical Mass. If chain-reaction is delayed, it will fizzle.

  15. #35
    Senior Member Hommie's Avatar
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    Default Re: Nuclear Explosion

    Do not to piss me off!

  16. #36
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    Default Re: Nuclear Explosion

    Quote Originally Posted by reno77
    You can also build your own crude fusion reactor.. not a practical one though as the power input is more than the output.

    http://www.fusor.us/fusor.html
    http://deseretnews.com/dn/view/0,1249,510054502,00.html
    Hmmm........

  17. #37

    Default Re: Nuclear Explosion

    Quote Originally Posted by Hommie
    Not completely true as Critical Mass is a result of chain-reaction and timing is everything to achieve the chain-reaction to form the Critical Mass. If chain-reaction is delayed, it will fizzle.
    okie... you see it this way.
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  18. #38
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    Default Re: Nuclear Explosion

    Quote Originally Posted by zaxh81
    Even after the Chernobyl incident,so many years on,no one could get near the center of explosion,they will melt due to the radiation.

    It's like a ghost town,objects are left intact,just that no living thing could be found.So sad.
    There used to have a webbie document the place but it's gone.
    there's residual contamination after the explosion, but no, people don't melt because of that...
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  19. #39

    Default Re: Nuclear Explosion

    Quote Originally Posted by Hommie
    Just wondering, any expert can enlighten me on whether a nuclear powered sub or aircraft-carrier will burst into a mushroom cloud like explosion when hit?
    A nuclear-powered engine works because heat is generated by the fissioning of the nuclear fuel. Two systems of pressurized water are sent through the nuclear engine. The first, or primary, system circulates water through the reactor, piping loops, pumps and finally to the steam generators, where the heat from the reactor is transferred to the secondary water system. The water from the primary system is then directed back to the reactor to be heated again. The heat transferred to the secondary system creates steam. This steam supplies the ship with electricity and propulsion when it moves through the turbine generators and propulsion turbines, respectively. The steam, condensed back to water, returns to the steam generators to be reheated
    ...but a direct hit will damage the reactor and will cause a disaster but not a nuclear explosion.

  20. #40
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    Default Re: Nuclear Explosion

    Quote Originally Posted by Hommie
    I have got it! More powerful than nuclear fission is nuclear fusion. Instead of splitting atoms' nucleus splits into two or more smaller nuclei plus some by-products, fusion is a process in which two nuclei join, forming a larger nucleus and releasing or absorbing energy.

    The fusion of lighter nuclei, which creates a heavier nucleus and a free neutron, will generally release even more energy than it took to force them together. The energy released in most nuclear reactions is much larger than that for chemical reactions, because the binding energy that glues a nucleus together is far greater than the energy that holds electrons to a nucleus.

    hydrogen bomb is one such example.
    Wah, chim

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