Answer:
The energy is conserved in the nuclear fission when the nuclear reactor mass releases the kinetic energy in the reaction and then source is known as the nuclear binding energy.
By using the Einstein mass energy equation that is E = m×c², we can easily determine the actual amount of the released energy. The nuclear fission is the process of subdividing the heavy mass of the atomic nucleus like uranium.
The nuclear fusion basically violate the law (Conservation of mass). During the nuclear fusion process the matter are not conserve because when the nuclei gets fuse then its mass are converted into the energy and then it is released.