Which of the following correctly describes how energy is released from uranium in nuclear reactors? A) Uranium nuclei radiate microwave radiation, which is absorbed by the material around the uranium in the core of the reactor, heating it up. B) Uranium nuclei radiate 𝛾-rays, which are absorbed by the material around the uranium in the core of the reactor, heating it up. C) Uranium nuclei emit electrons, which are used directly to generate electricity. D) The nuclei of uranium atoms split, releasing energy stored within the nucleus and causing the uranium and the material around it in the core of the reactor to heat up.
Our four options then are that the uranium in the reactor emits microwaves, that it emits 𝛾-rays, that it emits electrons, and that it splits and leads to a chain reaction. If we consider the process of uranium 235 nuclear fission, in this process, when a single neutron collides with a uranium 235 nucleus, that nucleus splits apart, forming isotopes of barium and krypton. And this split also releases three neutrons, which themselves go along continuing the reaction.
This means that, to generate nuclear energy, the process indeed involves the splitting of uranium atoms rather than the emission of a certain type of radiation from those atoms. This splitting of the atomic cores is described by the word “fission.” We see then that the answer to this question is option D, that the nuclei of uranium atoms split, which releases energy and heats the reactor elements and core up.