AN INTRODUCTION TO FISSION & FUSION Nuclear Reactions: AN INTRODUCTION TO FISSION & FUSION Farley Visitors Center

Fission Fissile nuclei are generally heavy atoms with large numbers of nucleons The nuclei of such heavy atoms are struck by neutrons initiating the fission process Fission occurs due to electrostatic repulsion created by large numbers of protons within the nuclei of heavy atoms

Fission A classic example of a fission reaction is that of U-235: U-235 + 1 Neutron 2 Neutrons + Kr-92 + Ba-142 + Energy In this example, a stray neutron strikes an atom of U-235. It absorbs the neutron and becomes an unstable atom of U-236. It then undergoes fission. Notice that more neutrons are released in the reaction. These neutrons can strike other U-235 atoms to initiate their fission.

Fission The fission process is an a natural one as a French researcher found a natural uranium reactor in Gabon, West Africa; it has been estimated to be over 2 billion years old Fission produces large amounts of heat energy and it is this heat that is captured by nuclear power plants to produce electricity

Fusion Fusion is a nuclear reaction whereby two light atomic nuclei fuse or combine to form a single larger, heavier nucleus The fusion process generates tremendous amounts of energy; refer back to Einstein’s equation For fusion to occur, a large amount of energy is needed to overcome the electrical charges of the nuclei and fuse them together

Fusion Fusion reactions do not occur naturally on our planet but are the principal type of reaction found in stars The large masses, densities, and high temperatures of stars provide the initial energies needed to fuel fusion reactions The sun fuses hydrogen atoms to produce helium, subatomic particles, and vast amounts of energy

Review Mass and Energy are two forms of the same thing; neither can be created nor destroyed but mass can be converted into energy (E = mc2) Fission is a nuclear reaction in which a heavy atomic nucleus is split into lighter atomic nuclei Fusion is a nuclear reaction in which 2 light atomic nuclei are combined into a single, heavier atomic nucleus