fission question

[GutZ]

So I was thinking when you are "splitting" atoms, particularly within like a fission based bomb there is quite amount of thermal energy released. Is there anyway to produce the same effect but instead of thermal energy being allowed, its coverted into kinetic energy?

 

I am guessing this would be called cold fission.

[Bluenoise]

I'm fairly rusting on my thermal dynamics, but isn't this thermal energy just kinetic energy in the form of vibrating/moving atoms.

[insane_alien]

bluenoise is right. the energy released IS kinetic (and some gamma). a lot of the energy is imparted to the daughter products which sends them flying off at a good fraction of the speed of light. if you mean to impart the energy into a vehicle then look up the orion project.

[swansont]

bluenoise is right. the energy released IS kinetic (and some gamma). a lot of the energy is imparted to the daughter products which sends them flying off at a good fraction of the speed of light. if you mean to impart the energy into a vehicle then look up the orion project.

 

Not quite, I think. An average fission of U-235 releases ~200 MeV, (and IIRC ~170 MeV of that as KE of the fission fragments) so I don't think that "a good fraction of c" accurately gives the speed of the daughter products. KE is of order .001 of the rest energy, which put them at maybe 0.05c. A little faster for the lighter fission fragments, a little slower for the heavy ones.

[ydoaPs]

Not quite, I think. An average fission of U-235 releases ~200 MeV, (and IIRC ~170 MeV of that as KE of the fission fragments) so I don't think that "a good fraction of c" accurately gives the speed of the daughter products. KE is of order .001 of the rest energy, which put them at maybe 0.05c. A little faster for the lighter fission fragments, a little slower for the heavy ones.

 

Learn that in Orlando?

[insane_alien]

oops, yeah, uhh... i was hungover. besides 0.05c is damn fast.

[swansont]

Learn that in Orlando?

 

Some of it.

[GutZ]

So all of it is KE?

 

Why the mushroom cloud and fire then?

[swansont]

So all of it is KE?

 

Why the mushroom cloud and fire then?

 

170 MeV is a LOT of KE for a couple of nuclei to have. As we saw above, these babies are moving a few percent of the speed of light, and even though i_a overstimated a little bit, that's still screaming fast. All of this KE gets deposited in the surrounding material. In a reactor, that's the structural support for the control rods, and that energy gets taken away by the cooling fluid, which is often water, which normally limits the temperature. In a bomb, it's the atmosphere. Things get super-toasty. It cools, I presume, mainly by expansion, which means that inside of a certain radius, you get disassociation of molecules and ionization of any atom that happens to be around, i.e. a fireball.

[GutZ]

170 MeV is a LOT of KE for a couple of nuclei to have. As we saw above, these babies are moving a few percent of the speed of light, and even though i_a overstimated a little bit, that's still screaming fast. All of this KE gets deposited in the surrounding material. In a reactor, that's the structural support for the control rods, and that energy gets taken away by the cooling fluid, which is often water, which normally limits the temperature. In a bomb, it's the atmosphere. Things get super-toasty. It cools, I presume, mainly by expansion, which means that inside of a certain radius, you get disassociation of molecules and ionization of any atom that happens to be around, i.e. a fireball.

 

Oh I see, I thought that was directly from the reactions itself. opps. Thanks