Nuclear energy can be produced by either of two types of reactions: fission, the splitting apart of a massive atomic nucleus, or by fusion of lighter nuclei into a heavier nucleus.
There are four major types of nuclear reaction:
1>>"fission", the splitting of a nucleus into two "daughter" nuclei:
n + 235U -> 141Ba + 92Kr + 3n;
2>>"fusion" of two "parent" nuclei into one daughter nucleus:
p + p -> 2 H + e+ + n + .42 MeV,
where n stands for a "neutrino"
3>>"neutron capture", used to create radioactive isotopes, in whichthe nuclear charge (Z, the atomic number) is unchanged,the nuclear mass (A = number of protons + neutrons, the atomic mass) increases by one,andthe number of neutrons (N) increases by one (note that N always = A - Z);and
4>>various "decay modes", in which nuclei "spontaneously" eject one or more particles and lose energy to become nuclei of lighter atoms.
