Uses of Nuclear
Radiation, Fission and
Fusion
© 2003 John Wiley and Sons Publishers
Figure 4.2: The penetrating power of radiation.
© 2003 John Wiley and Sons Publishers
Figure 4.4: The components of α rays, β rays, and γ rays.
Origins of radiation exposure
Natural Background
(cosmic rays, earth minerals)
81%
Medicine
and Diagnostics
15%
Consumer Products
(televisions sets,
smoke detectors) 4%
Human Exposure to Radiation
Uses of Nuclear
Radiation/Energy
•
•
•
•
Radioactive Dating
Medicine
– Chemotherapy
– Power pacemakers
– Diagnostic tracers
Agriculture
– Irradiate food
– Pesticide
– Fertilizer evaluation
Energy
– Fission
– Fusion
Carbon-14 dating
22,920 years ago
17,190 years ago
11,460 years ago
5730 years ago
Present
Radioisotopes in Medicine
Radioisotopes like
Tc-99 can be used to
detect bone cancer.
The Tc-99 accumulates
in areas of abnormal
bone metabolism and
then detection of the
nuclear radiation (gamma
rays) show the location of
the cancer.
Radioisotopes in Agriculture
-Radioactive tracers used to determine the effectiveness
of fertilizers.
- Cobalt-60 produces
gamma rays that are
used to irradiate
food.
Fission
• Nuclear fission occurs when scientists
bombard a large isotope with a neutron.
• This collision causes the larger isotope to
break apart into two or more elements.
• These reactions release a lot of energy.
• You can calculate the amount of energy
produced during a nuclear reaction using
an equation developed by Einstein: E=mc2
Chain Reaction Figure
Nuclear Power Plants
• If the neutrons can be controlled, then the
energy can be released in a controlled
way. Nuclear power plants produce heat
through controlled nuclear fission chain
reactions.
• The fissionable isotope is contained in fuel
rods in the reactor core. All the fuel rods
together comprise the critical mass.
• Control rods, commonly made of boron
and cadmium, are in the core, and they act
like neutron sponges to control the rate of
radioactive decay.
Nuclear Reactors
• The reaction is kept in
check by the use of
control rods.
• These block the paths of
some neutrons, keeping
the system from reaching
a dangerous supercritical
mass.
Nuclear Power Plants (cont)
• In the U.S., there are approximately 100 nuclear reactors,
producing a little more than 20% of the country’s
electricity.
• Advantages
– No fossil fuels are burned.
– No combustion products (CO2, SO2, etc) to pollute the air and
water.
• Disadvantages
–
–
–
–
Cost - expensive to build and operate.
Limited supply of fissionable Uranium-235.
Accidents (Three Mile Island & Chernobyl)
Disposal of nuclear wastes
Nuclear Reactors
In nuclear reactors the heat generated by the
reaction is used to produce steam that turns a
turbine connected to a generator.
What is Nuclear Fusion?
• Nuclear Fusion is the energy-producing process taking place in the
core of the Sun and stars
• The core temperature of the Sun is about 15 million °C. At these
temperatures hydrogen nuclei fuse to give Helium and Energy.
The energy sustains life on Earth via sunlight
Energy from Fusion
2
3
H
H
+
1
1
4
1
Energy
He
n
+
+
2
0
Nuclear Fusion
• Fusion would be a superior
method of generating power.
– The good news is that the
products of the reaction are
not radioactive.
– The bad news is that in order to achieve fusion, the
material must be in the plasma state at several million
kelvins.
– Tokamak apparati like the one shown at the right show
promise for carrying out these reactions.
– They use magnetic fields to heat the material.