Nuclear Fission

1
Homer "Where are we going, sir?"Burns "To
create a new and better world."Homer "If it's
on the way, could you drop me off at my house?"
2
History of Nuclear Power

• James Chadwick first identified free neutrons in
  1932.
• These neutrons were relatively heavy and able to
  plough through electrons surrounding the nucleus
  of other atoms
• Neutrons are electrically neutral and are not
  deflected by positive nuclear charge

3
Enrico Fermi

• Physicist who studied nuclear physics
• Discovered that firing these free neutrons at
  elements caused them to become radioactive and
  emmit ß-particles

4
Discovery of Nuclear Fission

• 1939 Lise Meitner and Otto Frisch proposed that
  the splitting of a heavy nucleus by way of
  absorbing a neutron, caused the atom to become
  unstable and split into two lighter nuclei.
• This process was called Nuclear Fission and they
  observed that this reaction released a great deal
  of energy.

5
Nuclear Fission

• Fermi later discovered that the fission reaction
  might release free neutrons which could cause
  further fission reactions
• A chain reaction could occur releasing a great
  deal of energy in a short time, a nuclear
  explosion.

6
Enrichment

• Niels Bohr was the first to establish that the
  U-235 isotope readily underwent fission, but the
  U-235 isotope is diluted in natural uranium by
  140 atoms of U-238
• Enrichment was a way to increase the proportion
  of U-235 and aid in the chain reaction.

7
Manhattan Project

• 1941- President Roosevelt put resources into the
  development of the atomic bomb
• This lead to further studies of nuclear fission
  and the discovery of the first controlled chain
  reaction. achieved by Fermi and a group of
  scientists at the University of Chicago

8
Small Steps Toward Power Production

• December 20, 1951 experimental reactor produced
  enough power to light four 150 watt light bulbs
• July 17, 1955 - Argonne Lab designed first
  reactor to provide power for an entire town
  (Arco, Idaho).
• 1957 - The Atomic Energy Commission sponsored a
  60 megawatt breeder reactor plant in
  Shippingport, PA.

9
First Commercial Power Plant

• 1959 Dresden Unit One was built at a cost of
  18 million in Morris, Illinois.
• 200 MW Duel Cycle Boiling Water Reactor
• Designed and operated by General Electric until
  1979 when it was shut down.

10
Nuclear Fission

• A mechanism by which a heavy nucleus absorbing a
  neutron might become unstable and split into two
  lighter nuclei.

Source Energy Systems Sustainability
11
Inducing Fission

• Absorption of a free Neutron
• free protons / other nuclei can also induce
  fission
• Easiest in Heavy elements
• fission in elements heavier than Fe ? Output E
• fission in elements lighter than Fe ? Input E
• Abundance / Easy of Fission
• Uranium heaviest naturally occurring element
• Plutonium undergoes spontaneous fission

Source How Stuff Works
12
Chain Reaction

• Initiation ? 2 or more neutrons ? neutrons
  escape/initiate more fission.
• High Concentration of U-235 required to maintain
  chain reaction

Animation of Fission Chain Reaction
Source ThinkQuest 98
13

• Critical Mass- The amount of material of a given
  shape and volume to maintain a chain reaction

Source Energy systems sustainability
14
Products of Fission

• 2 new radioactive nuclei
• 2 or 3 free neutrons
• Heat / Gamma Radiation
• ENERGY

Source Nuclear Fission and Nuclear Fusion
15
Where does the Energy come from?

• Sum of Mass of products lt Original Mass
• Missing Mass (0.1 of Original Mass) has been
  converted to energy
• E?mc2
• U235 n ? fission 2 or 3 n 200 MeV

Source Think Quest
16
E?mc2

• A very small amount of matter is equivalent to a
  vast amount of energy. 
• For example, 1 kg (2.2 lb) of matter converted
  completely into energy would be equivalent to the
  energy released by exploding 22 megatons of TNT.

Source Nuclear Fission and Nuclear Fusion
17
Nuclear Fusion

• the comming together of two lighter nuclei to
  form one heavier one
• Process that powers the stars
• Original source of almost all of earths energy

Source Joint European Torus (JET)
18
How Fusion works

• Most suitable reaction involves
• Deuterium (D)
• Tritium (T)
• (Isotopes of Hydrogen)
• Temperatures of gt10 million deg. C
• Plasma State in which electrons have been
  removed from atomic nuclei

Nuclear Fusion Animation
Source Joint European Torus (JET)
19
Means of Initiating Fusion
Source FusEdWeb Fusion Energy Educational Web
Site
20
Fusion by Magnetic Confinement

• PLASMA is so high in energy it requires Magnetic
  Fields to contain it.
• Magnetic fields trap superheated fusion fuel in
  center of loop.
• Immense temperatures/pressures

Source FusEdWeb Fusion Energy Educational Web
Site http//fusedweb.pppl.gov/
21
Why does Fusion yield Energy?

• Mass of Products is less than mass of reactants.
  
• Emc2
• mass converted to kinetic energy

Source FusEdWeb Fusion Energy Educational Web
Site
22
Where does Tritium Deuterium Come from?

• Tritium
• Bombarding Lithium with a Neutron

• Deuterium
• Plentiful in ordinary water.
• 1/6500 hydrogen atoms in water is Deuterium
• 1 gallon of water conceivably has the energy
  content of 300 gallons of gasoline

Source General Atomics http//fusedweb.pppl.gov/
23
Yield of Fission vs. Fusion
Source General Atomics
24
Nuclear Fuel Cycle
25
Reactor Core
26
Moderators

• Slows the neutrons in order to maintain chain
  reaction

27
Light Water Moderator

• Ordinary Water
• light-water reactors require slightly enriched
  (up to 20 U-235) uranium fuel to sustain the
  fission reaction.
• 4/5 of todays reactors are light water
• Reactor Types Boiling and Pressurized Water

28
Pressurized Water Reactor

29
Boiling Water Reactor

30
Heavy Water Moderator

• Hydrogen-2 or Deuterium (D20)
• Uses Natural Uranium as oppose to Enriched
  uranium
• isolating the small amount of D2O present in
  natural water requires considerable amounts of
  electricity.
• Reactor Types CANDU and Steam Generating Heavy
  Water Reactor

31
Graphite Moderator

• Most Easily Available Effective Moderator
• Derived from Carbon(graphite)
• Heavier than the Deuteron but neutron absorption
  low
• Reactor Types Advance Gas Cooled Reactor

32
Spent Fuel

• 2 Distinct Processes
• Direct Disposal
• Reprocessing

33
Consumption

• Nuclear power provides about 6 of the worlds
  primary energy.
• 439 Total Reactors in 31 different countries.
• 103 in the US
• 59 in France
• 53 in Japan
• Three countries receive more than half of their
  electricity from nuclear France, Lithuania,
  Belgium.
• US gets 20 of electricity from nuclear

34
Pros

• Abundant
• Reliable
• Relatively safe
• Little pollution
• Radiation

35
Cons

• Meltdowns lack of coolant in the core
• Waste Disposal- high and low level
• Radiation- weak carcinogen

36
Radioactivity Pro and Con

• Did you know that some of the foods we eat have
  been treated by exposure to radiation?
• Have you ever wondered how we know the age of
  dinosaur bones?
• Have you ever known anyone who was treated for
  cancer with radiation therapy?
• Have you ever wondered how a nuclear submarine is
  powered?
• Have you ever had an x-ray to look for a broken
  bone?

37
Environmental Effects

• Radioactivity
• Waste heat
• Sulfur Dioxide
• Air quality

38
Nuclear Efficiency

• Nuclear power plants need to be re-fueled only
  once every year, while coal power plants require
  a trainload of coal per day.
• The energy that can be obtained from one pound of
  uranium is equal to the amount of energy in
  approximately million pounds of coal.

39
Benefits of Nuclear Energy

• Nuclear power is the only energy producing
  technology which takes full responsibility for
  all its wastes and fully costs this in the the
  product.
• The amount of radioactive wastes are very small
  relative to wastes produced by fossil fuels .
• Spent nuclear fuel may be treated as a resource.

40
Uranium Resources

• Known Recoverable Resources of Uranium
•  
• tonnes U
• percentage of world
• Australia
• 863,000
• 28
• Kazakhstan
• 472,000
• 15
• Canada
• 437,000
• 14
• South Africa
• 298,000
• 10
• Namibia
• 235,000

41
Uranium Availability
Known recoverable resources of Uranium (1999 data)      
Country Tonnes World total  
Australia 889,000 27  
Kazakhstan 558,000 17  
Canada 511,000 15  
South Africa 354,000 11  
Namibia 256,000 8  
Brazil 232,000 7  
Russian Federation 157,000 5  
US 125,000 4  
Uzbekistan 125,000 4  
World total 3,340,000    
       
At current usage --gt 48 yrs      
42
Greenhouse Gas Emissions

• Worldwide emissions of CO2 from burning fossil
  fuels total about 25 billion tonnes per year.
  About 38 of this is from coal and about 43 from
  oil. If uranium is used in a nuclear power
  reactor, these emissions do not occur.

43
Safety Factor
44
References

• Basic Nuclear Fission. ThinkQuest. Accessed
  from http//library.thinkquest.org/17940/texts/fi
  ssion/ fission.html?tqskip11. on 2-13-05.
• General Atomics. FusEdWeb Fusion Energy
  Educational Web Site. accessed from
  http//fusedweb.pppl.gov/. on 2-13-05.
• Godfrey Boyle, Bob Everett, Janet Ramage. Energy
  Systems and Sustainability. Oxfoord University
  Press 1998.
• How Stuff Works. How Nuclear Power Works.
  Accessed from http//people.howstuffworks.com/nuc
  lear-power2.htm. on 2-13-05.
• Nuclear Fission and Nuclear Fusion. Accessed
  fromhttp//chemed.chem.purdue.edu/genchem/
  topicreview/bp/ch23/fission.html. on 2-13-05.
• http//www.chem.duke.edu/jds/cruise_chem/nuclear/
  pros.html
• http//starfire.ne.uiuc.edu/ne201/1996/kopke/prob
  lems.html
• http//members.tripod.com/funk_phenomenon/nuclear/
  procon.htm
• http//www.world-nuclear.org/info/inf69.htm
• http//nuclearhistory.tripod.com/history.html
• www.chemcases.com