1. Chapter 5 Energy Resources
Section 3
Nuclear Energy
Notes 5-3

2. Nuclear Reactions Nucleus of an atom: Convert matter into energy
Central core made of protons (+) and neutrons (neutral)
Convert matter into energy
Einstein developed the equation
E = mc2
E = energy
m = mass
c = speed of light (constant)
It only takes a small amount of matter to create a large amount of energy

3. Nuclear Reactions Nuclear fission:
Splitting the nucleus of atoms into smaller pieces
Uranium-235 (U-235)
A neutron is shot at the nucleus and it splits it into two smaller nuclei and two or more neutrons
The mass is less than the original
The missing is transferred to energy

4. Nuclear Reactions Nuclear fission:
The other neutrons go off to hit other nuclei
This creates a chain reaction
Each time a large amount of energy is produced
If the reaction is not controlled, it can cause disaster
Nuclear bomb; atomic bomb
Energy can be released as heat when controlled
This can be used to create electricity

5. Nuclear Power Plants
Heat from nuclear reactions is used to heat water to steam
Steam turns the turbine to create electricity
Reactor Vessel
Where the nuclear fission occurs
Fuel rods made of U-235
Control rods made of cadmium

6. Nuclear Power Plants Reactor Heat Exchanger:
Less control rods in place makes the reaction go faster; and get hotter
More control rods absorbs neutrons and slow down reaction; and get cooler
Heat Exchanger:
Water is used to cool the reactor; heat is transferred to other water that turns to steam
Steam turns the turbine; make electricity

7. Risks of Nuclear Fission
Chernobyl, Ukraine (1986)
Nuclear reactor overheated and caused a meltdown
The excessive heat increased the steam to the generator
This caused explosions that blew the roof off and leaked radioactive materials into the environment
Still is contaminated today

8. Risks of Nuclear Fission
Disposal of nuclear wastes
Remain radioactive for thousands of years
They must be stored safely for many years
Safety
The safety requirements for nuclear plants are very extensive and expensive

9. Nuclear Fusion The source of energy for the sun
Combines two atomic nuclei to make one larger nuclei
Hydrogen nuclei are forced together to make a helium nuclei
H-2 (deuterium) and H-3 (tritium) are the fuel
H-2 has one neutron and H-3 has two neutrons
Need a temperature of 10 million C°

10. Nuclear Fusion Helium has a smaller mass than two hydrogen
The difference is converted to energy
Use hydrogen from water as a source on Earth
Safer, less pollution and more energy than fission

11. Nuclear Fusion Not able to control on Earth Too hot to make it work
Needs to great a pressure
Can’t find material to create the reactor
Could use magnetic fields
Uses more energy to make field than the reactor produces