Using the Nucleus as a Source of Energy
A. Nuclear Energy
• Two types of nuclear processes can
produce energy
– fission
– fusion
Using the Nucleus as a Source of Energy
B. Nuclear Fission
Fission - Splitting a heavy nucleus into 2
nuclei with smaller mass numbers
Using the Nucleus as a Source of Energy
B. Nuclear Fission
• Chain reaction – self sustaining fission process caused by
the production of neutrons that proceed to split other
nuclei
• Critical mass – mass required to sustain a chain reaction
Using the Nucleus as a Source of Energy
Chain Reaction
Using the Nucleus as a Source of Energy
Nuclear Fusion
• Process of combining two nuclei to form
one nucleus of larger mass
• Produces more energy per mole than
fission
• Powers the stars and sun
Using the Nucleus as a Source of Energy
Fusion Reactions
Using the Nucleus as a Source of Energy
Nuclear Fusion
• Requires extremely high temperatures
• Currently not technically possible for us to use as an
energy source
Using the Nucleus as a Source of Energy
A nuclear reactor produces and controls the release of energy
using FISSION REACTIONS. In a nuclear power
reactor, the energy released is used as heat to make steam to
generate electricity.
The isotope 235U is commonly used as the fissile material
in a nuclear reactor.
Using the Nucleus as a Source of Energy
C. Nuclear Reactors
Using the Nucleus as a Source of Energy
Reactors components
• Fuel: Usually pellets of UO2 arranged in tubes to
form fuel rods, part of the core of the
reactor.
• Moderator: A material that slows down neutrons;
Normal or “light” water is the normal moderator
heavy water (HDO) or graphite also used.
• Control rods: neutron-absorbing material
such as cadmium, and are
used to control the rate of the reaction, or stop it.
Using the Nucleus as a Source of Energy
Coolant: a liquid or gas circulating through the core
so as to transfer heat from it. Most reactors use
water.
Containment: structure around the reactor core which
is designed to contain radioactivity in
case of failure
Using the Nucleus as a Source of Energy
C. Nuclear Reactors
Reactor core
Using the Nucleus as a Source of Energy
Nuclear Power Plants
map: Nuclear Energy Institute
Using the Nucleus as a Source of Energy
25.3
Using the Nucleus as a Source of Energy
Nuclear Waste
• Nuclear Waste
– Why are spent fuel rods from a nuclear reaction
stored in water?
25.3
Using the Nucleus as a Source of Energy
Nuclear Waste
Water cools the spent rods, and also acts
as a radiation shield to reduce the
radiation levels.
25.3
Using the Nucleus as a Source of Energy
Nuclear Waste
• Nuclear Waste
– Where does all the waste from reactors go?
High-level Nuclear Waste sites in the USA
Using the Nucleus as a Source of Energy
Yucca Mountain Hydrology
Using the Nucleus as a Source of Energy
25.3
Using the Nucleus as a Source of Energy
Nuclear Fusion
• Nuclear Fusion
– How do fission reactions and fusion reactions differ?
Using the Nucleus as a Source of Energy
C. Fission vs. Fusion
F
I
S
S
I
O
N
• 235U is limited
• danger of meltdown
• toxic waste
• thermal pollution
F
U
S
I
O
N
•
•
•
•
fuel is abundant
no danger of meltdown
no toxic waste
not yet sustainable