Nuclear Fission and Fusion

1. Honors Chemistry Nuclear Fission and Fusion

2. Review • Why do elements undergo radioactive decay? • Be able to explain this in terms of band of stability. • Transmutation • Process of the conversion of one atom of one element to an atom of another element. • Occurs through radioactive decay, like we have already discussed or… • It can occur when we bombard the nucleus of an atom with sub atomic particles. • All elements with an atomic number above 92, undergo transmutation.

3. The Basics of Nuclear Fission • Think back to the transmutation we just talked about… • Change of an atom from one element to another. • Follows the second process of bombardment. • Nuclear Fission • Splitting of a nucleus into smaller fragments when bombarded with neutrons.

4. Nuclear Fission • Only fissionable nuclei • Uranium-235 and plutonium-239 • Do these sound familiar? Why? • In this reaction, the nucleus is broken into smaller nuclear fragments, more neutrons are released, and large amounts of energy. This leads to the nuclear chain reaction.

5. Controlling Fission • 2 processes used to control fission • Neutron Moderation • Water or carbon source is used to slow down neutrons so nuclei can absorb them. • Neutron Absorption • To prevent chain reaction from going too fast, the slow moving neutrons are captured by control rods (cadmium). • Removal of control rods or failure of control rods leads to nuclear meltdowns.

6. Nuclear Fusion • Fusion- • Nuclei combine to produce a nucleus of a greater mass. • Releases much more energy than a fission reaction. • Only occur at extremely high temperatures

7. Use of Nuclear Fusion • Appealing source of energy • However, the heat required to begin the fusion processes has only occurred in the fusion bomb. • Clearly, that’s not a controlled process.