1. Nuclear Power Plants

2. 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.

3. 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 (CO 2, SO 2, 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

4. A nuclear power plant. Heat produced in the reactor core is transferred by coolant circulating in a closed loop to a steam generator, and the steam then drives a turbine to generate electricity.

5. Three Mile Island

6. Chernobyl

8. Atomic Bombs Because of the tremendous amount of energy released in a fission chain reaction, the military implications of nuclear reactions were immediately realized. The first atomic bomb was dropped on Hiroshima, Japan, on August 6, 1945. In an atomic bomb, two pieces of a fissionable isotope are kept apart. Each piece by itself is subcritical. When it’s time for the bomb to explode, conventional explosives force the two pieces together to cause a critical mass. The chain reaction is uncontrolled, releasing a tremendous amount of energy almost instantaneously.

9. Some practical uses of Radioisotopes (dating, chemical tracers, industrial applications, medical applications, nuclear power plants) Medical Uses 60 Co (cobalt-60) used in cancer treatments and used to kill bacteria in food products 226 Ra (Radium-226) used in Cancer treatment 131 I diagnosis and treatment of thyroid disorders 11 C Positron emission tomography (PET scans) Other Uses 14 C archaeological dating (of once living things) and radiolabelled organic compounds 238 U archaeological dating (U-238 to Pb-206 ratio) 241 Am (Americium-241) smoke detectors 235 U nuclear reactors and weapons

10. Human Exposure to Radiation

13. How Nuclear Power Plants Work http://www.youtube.com/watch?v=VJfIbBDR3e8