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S A C C O N E A P E S
Chapter 11: Nuclear Energy
http://www.nrc.gov/
Nuclear Energy
• In contrast to a chemical reaction, a nuclear reaction involves changes within the nuclei of an atom.
• Small amounts of matter = large amounts of energy.
Structure of an atom chemical energy
Produce 100,000 times more energy per atom than chemical reactions.
Nuclear weaponry releases this energy all at once.
Nuclear Energy
Nuclear energy plants control the rate of the energy released.
Nuclear Energy
Isotopes of Hydrogen
Deuterium: 1 proton and 1 neutron (hydrogen usually has no neutrons).
http://www.purchon.com/chemistry/atoms.htm
Tritium: 1 proton and 2 neutrons. (Radioisotope of Hydrogen)
Radio Isotopes
• These are unstable isotopes and are referred to as radioactive.
• They spontaneously emit radiation.
• (Alpha particles, Beta particles, and Gamma rays)
Radiation: particles or rays of energy that result from the decay of a nucleus of a particular element into that of another
element.
Radioactive Decay
• When an atomic nuclei naturally breaks apart into smaller, less crowded nuclei of a different element.
• Uranium 235 (U 235) decays into Lead 207 (Pb 207)
Radioactive Half-Life
• The period of time required for one half of the total amount of a radioactive substance to change into a different element.
Nuclear Fuel Cycle
• The processes involved in producing the fuel used in nuclear reactors (Uranium ore) and in disposing of radioactive wastes.
Uranium ore needs to be refilled through enrichment to obtain the 3% U 235 from the ore which has
0.71 %.
Nuclear Reactors
• Uranium pellets are used to obtain energy . Each pellet is equivalent to the energy found in a ton of coal (2000 1bs).
Nuclear Fuel Cycle
• Pellets are inserted into fuel rods (12 ft long) which are grouped into fuel assemblies (200 rods/assembly)
Nuclear Reactors• Most reactors contain 250 assemblies.• U235 is bombarded with neutrons which
causes a fission reaction (splitting) of the nucleus.
• This initial splitting frees up additional neutrons which then bombard more U 235 nuclei which frees more neutrons which splits more U 235 nuclei...
• This is called a chain reaction or “cascade effect.”
Nuclear Fission
Nuclear Reactors Consist of a ...• 1 ) Reactor core: Fission takes place heat.
• 2) Steam Generator: heat from reactor core produces steam.
• 3) Turbine: steam spins the turbine to generate electricity.
• 4) Condenser: cools the steam back to liquid water.
Reactor core • Fission takes place here.
• This area contains the fuel assemblies.
• Each assembly has a control rod which absorbs neutrons.
• By lowering and raising the control rod an operator can control the rate of the fission reaction.
Lower the rod: less fission.
Higher the rod: more fission
Primary circuit: heats water to 293 °C (which is 560°F), using the energy from the fission reactor.
High pressure keeps the water in liquid form.
Water Circuits
Secondary circuit: boils water to steam and then converts back to liquid. Turbine is spun due to steam and change in pressure from cooling.
Water Circuits
Tertiary circuit: provides cool water to the condenser (which cools the spent steam in the secondary circuit).
As this water is heated, it is transferred from the condenser to the cooling tower (“lake").
Once cool, the water is sent back to the condenser.
Water Circuits
Breeder Nuclear Fission
Not Fissionable
Safety
• Nuclear reactors contain huge steel structures called reactor vessels that will prevent the release of radiation leaks.
• This vessel is placed in a containment building which is an additional precaution to prevent radiation leakage. (Earthquake, tornado, & "plane proof' steel reinforced concrete walls 3-5 ft. thick.)
Safety: 3 Mile Island
• “Black Friday”Middletown, PA March 1979
• Nuclear reactor 50% meltdown, still can’t enter the reactor today.
• Radioactive gas vented into the environment.
Safety: 3 Mile Island
• No new permits for reactors in the US since 3 mile island.
• NRC opened up the permit issuing process again in 2000.
Chernobyl, Ukraine
Possible Fusion reaction
The problem on Earth is high temperature needed (15 million degrees), and containment (tokamak= magnetic bottle)
The end?
Extra credit #1
• What is this cartoon trying to get across about nuclear energy?
Extra credit #2
• What does this symbol represent?
Extra credit #3
• What does Pu represent?
The accident at three mile island happened 12 days after the release of
what movie?
Extra credit #4
