binding-energyenergynuclear-physicsthermodynamics
My physics book mentions that its kinetic energy being released from the splitting of atoms, but it makes more sense for it to be heat energy as the construction of a power plant as shown below is using the energy to heat water to produce steam. Is it really Kinetic energy released from fission or Heat energy, as if it was kinetic then couldn't we directly transfer the kinetic energy to the turbine, without the need of steam.
The forces driving these two atoms apart are electrostatic forces of repulsion. Thus the kinetic energy that these atoms receive comes from the electrostatic interaction. This kinetic energy is later transformed into heat in an atomic reactor when two released atoms slow down colliding with the molecules of water.
I think in nuclear processes one should give importance to strong forces of attraction of nuclear nature rather than electrostatic forces between charged nucleons/or role of atomic electrons.
The enormous quantity of energy release in a fission can be qualitatively understood with the help of binding energy or binding fraction of a nucleus which is ratio of Binding energy and mass number(B/A) usually called f(b). For Uranium f(b)=7.6 MeV per nucleon.
The fragments produced by fission have mass numbers near the middle of the periodic table having f(b) of the range 8.5 MeV-
Thus by the breaking up approx. 0.9 MeV energy per nucleon gets released ;which comes out to be around 212 Mev for Uranium fission. Alternatively Q value of fission reaction can also be estimated which comes to 201 Mev for Uranium absorbing a thermal neutron and breaking into Ba and Kr with 3 neutrons.
I wish to point out that the nuclear fission process itself gets a good amount of energy released due to changes in binding energy of nucleons involved and electrostatic energy conversion does not play any significant role in this nuclear exoergic process.
Therefore one must revise the picture of Electrostatic energy going to Kinetic energy and then thermal energy of the fission process- as their contribution is minimal.
In a fission reaction it's nuclear potential energy that is converted to kinetic energy.
The nucleons are bound together in the nucleus by the strong nuclear force. The total amount of energy it would take overcome this force and disassemble the nucleus to individual protons and neutrons is called the nuclear binding energy.
The same nucleons exist before and after a fission reaction but the total amount of nuclear binding energy depends what which nucleus (or nuclei) they are in. See the graph below.
The average binding of energy of the nucleons becomes greater when the uranium atoms undergo fission and form lighter nuclei. This is to say it would now take even more energy to disassemble all to individual protons and neutrons. It's a bit like falling further down a hole. It now takes more energy to get out.
The nuclear potential energy is mostly converted into kinetic energy of the daughter nuclei, a small fraction (about 6%) of the energy goes into gamma rays and fast neutrons.
The mass of the products is less than the mass of the original nucleus as calculated by $E=mc^2$ but this is not unique to nuclear reactions, the same would be true for burning coal or letting water flow over a dam. It's just that in most non nuclear reactions the change is mass in immeasurably small.
Best Answer
The fission fragments, a couple of smaller nuclei, a few neutrons, some photons, and some neutrinos, all have kinetic energy as a result of the fission.
In their travels thorough the nuclear reactor the fission fragment often hit atoms and transfer some of their kinetic energy to those atoms which consequently move faster and have more kinetic energy. Moving faster in a random manner and having more kinetic we equate to a rise in temperature, so the reactor core becomes "hotter".