1. Fission and Fusion
Chp 24

3. Fission-Nuclear Power
Fission-Nuclear Power
Nuclear power plants use nuclear fission to generate a large release of energy as heat to generate electricity.
Nuclear reactions use control rods to absorb free neutrons and control the rate of the self sustaining chain reaction to prevent a meltdown.
Concerns: accidents and storage of radioactive waste.

4. Chain Reaction
Each fission of U-235 releases additional neutrons.
If one fission reactions produces two neutron, these two neutrons can cause 2 additional fissions.
So on and so on
This self sustain process in which one reaction initiates the next is called a chain reaction.
An atomic bomb is an example of an uncontrolled chain reaction.
What is used in reactors to control fission?

5. Fusion-Sun’s Power
Stars (our Sun) are the sites of fusion where heavy elements are created and large amounts of energy are released.
Advantages: Lightweight isotopes are abundant, products are not radioactive.
Scientists are researching fusion in the Tokamak reactor where
high temperatures (5,000,000 K) and strong magnetic fields to contain the very short lived reaction.

6. Steller Nucleosynthesis
Elements from Hydrogen to
Iron are created in large stars.
High temps and pressures cause light weight
Elements to fuse and to produce heavier
and heavier elements.
Once the core of a star is iron, the star will go
Supernova and explode, releasing elements
into space.

7. Tokamak Reactor-Fusion on Earth!
Reactants are in the form of plasma
Extremely strong magnetic fields to suspend charged plasma particles to prevent contact with container walls