Homer: "Where are we going, sir?" Burns: "To create a new and better world."...

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?"

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

Enrico Fermi

Physicist who studied nuclear physics

Discovered that firing these free neutrons at elements caused them to become radioactive and emmit β-particles

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.

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.

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.

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

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.

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.

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

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

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 ReactionSource: ThinkQuest ‘98

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

Source: Energy systems & sustainability

Products of Fission

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

Source: Nuclear Fission and Nuclear Fusion

Where does the Energy come from?

Sum of Mass of products < Original Mass

“Missing” Mass (~0.1% of Original Mass) has been converted to energy

E=Δmc^2

U235 + n → fission + 2 or 3 n + 200 MeV

Source: Think Quest

E=Δmc^2

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

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)

How Fusion works

Most suitable reaction involves:– Deuterium (D)– Tritium (T)

(Isotopes of Hydrogen)

Temperatures of >10 million deg. C

Plasma: State in which electrons have been removed from atomic nuclei

Nuclear Fusion AnimationSource: Joint European Torus (JET)

Means of Initiating Fusion:

Source: FusEdWeb: Fusion Energy Educational Web Site

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/

Why does Fusion yield Energy?

Mass of Products is less than mass of reactants.

E=mc^2 mass converted to

kinetic energy

Source: FusEdWeb: Fusion Energy Educational Web Site

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 Atomicshttp://fusedweb.pppl.gov/

Yield of Fission vs. Fusion

Source: General Atomics

Nuclear Fuel Cycle

Reactor Core

Moderators

Slows the neutrons in order to maintain chain reaction

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 today’s reactors are light water Reactor Types: Boiling and Pressurized

Water

Pressurized Water Reactor

Boiling Water Reactor

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

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

Spent Fuel

2 Distinct Processes:

Direct Disposal

Reprocessing

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

Pros

AbundantReliableRelatively safeLittle pollutionRadiation

Cons

Meltdowns – lack of coolant in the coreWaste Disposal- high and low levelRadiation- weak carcinogen

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?

Environmental Effects

RadioactivityWaste heatSulfur Dioxide Air quality

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.

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.

Uranium ResourcesKnown Recoverable Resources* of Uranium

 tonnes U

percentage of worldAustralia

863,00028%

Kazakhstan 472,000

15%Canada

437,00014%

South Africa 298,000

10%Namibia

235,0008%

Brazil 197,000

6%Russian Fed.

131,0004%

USA 104,000

3%Uzbekistan

103,0003%

World total ,107,000 

* Reasonably Assured Resources plus Estimated Additional Resources - category 1, to US$ 80/kg U, 1/1/01, from OECD NEA & IAEA, Uranium 2001: Resources, Production and Demand. Brazil, Kazakhstan and Russian figures above are 75% of totals.

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 --> 48 yrs      

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.

Safety FactorFuel Immediate fatalities 1970-92 Who? Deaths per TWy* electricity

Coal 6400 workers 342

Natural gas 1200 workers & public 85

Hydro 4000 public 883

Nuclear 31 workers 8

References

“Basic Nuclear Fission.” ThinkQuest. Accessed from: http://library.thinkquest.org/17940/texts/fission/ fission.html?tqskip1=1. 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/nuclear-power2.htm. on 2-

13-05. “Nuclear Fission and Nuclear Fusion.” Accessed from:http://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/problems.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