1. Uses of Nuclear Radiation, Fission and Fusion

2. Figure 4.2: The penetrating power of radiation.
© 2003 John Wiley and Sons Publishers
Figure 4.2: The penetrating power of radiation. 2

3. Figure 4.4: The components of α rays, β rays, and γ rays.
© 2003 John Wiley and Sons Publishers
Figure 4.4: The components of α rays, β rays, and γ rays. 3

4. Origins of radiation exposure
Natural Background
(cosmic rays, earth minerals)
81%
Medicine
and Diagnostics
15%
Consumer Products
(televisions sets,
smoke detectors) 4%

5. Human Exposure to Radiation

6. Uses of Nuclear Radiation/Energy
Radioactive Dating
Medicine
Chemotherapy
Power pacemakers
Diagnostic tracers
Agriculture
Irradiate food
Pesticide
Fertilizer evaluation
Energy
Fission
Fusion

7. Carbon-14 dating
22,920 years ago

8. 17,190 years ago

9. 11,460 years ago

10. 5730 years ago

11. Present

12. 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.

13. Radioisotopes in Agriculture
-Radioactive tracers used to determine the effectiveness
of fertilizers.
Cobalt-60 produces
gamma rays that are
used to irradiate
food.

14. 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

15. Chain Reaction Figure

16. 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.

17. 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.

18. 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

19. Nuclear Reactors
In nuclear reactors the heat generated by the reaction is used to produce steam that turns a turbine connected to a generator.

20. 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

21. Energy from Fusion H 2 1 + He 4 n 3
Energy

22. 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.