nuclear fusion energy rishi gohil che 379: energy technology and policy dr. thomas edgar fall 2007
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Nuclear FusionNuclear FusionEnergy Energy
Rishi Gohil
ChE 379: Energy Technology and Policy
Dr. Thomas Edgar
Fall 2007
Nuclear Fusion PrincipleNuclear Fusion Principle
• Energy generated by joining two elements with low atomic numbers.
• Most efficient reaction known is fusion of Hydrogen isotopes, Deuterium and Tritium, to form Helium.
• Fusion is source of energy for stars and the Sun.• High temperatures > 100 million degrees Kelvin
needed for fusion on earth• At high temperature, the gas mixture forms a
plasma (hot, electrically charged gas)
Nuclear FusionNuclear Fusion
• This reaction releases 17.6 MeV of energy. No limit on amount of fusion that can occur (unlike fission).
Requirements for Fusion ReactionRequirements for Fusion Reaction
• Plasma Temperature:100-200 million Kelvin – Needed to overcome natural positive repulsive forces
of plasma ions
• Energy Confinement Time: 4-6 seconds– The Energy Confinement Time is a measure of how
long the energy in the plasma is retained before being lost.
• Central Density in Plasma:1-2 x 1020 particles m-
3
– Large density needed because number of fusion reactions per unit volume is roughly proportional to the square of the density
ChallengesChallenges
• Current research in controlling high temperature plasma– How to heat plasma to >100 million deg C.– How to confine such a plasma– How to sustain the reactions.
AdvantagesAdvantages• Abundant fuels: Deuterium (from water),
Tritium (from Lithium) and Lithium (plentiful on Earth’s crust).
• Inherently safe: Because conditions for reaction are stringent and small amounts of fuel used
• Environmentally safe: No greenhouse gas emissions and byproduct of reaction is Helium.
JET (Joint European Torus)JET (Joint European Torus)• JET: World’s largest nuclear fusion
research facility
Fusion ReactorFusion Reactor
• EU to build pilot fusion reactor, Iter.– Cost: 4.57 Billion EURO (2000 prices) over 10 yrs– Life: 35 years– Countries Involved: 7– Design: reactions occur in 100 million degree gas (plasma)
suspended in donut shaped magnetic field.– Problems: Sustained and stable reactions– Potential: 500 MW output from 70 MW power input during
pulses of at least 400 secs.– If technology works commercial reactor, Demo, will be built.– Advantages: No greenhouse emissions, inherently safe due to
malfunction shutdown systems, no high-level long-lived radioactive waste produced.
ReferencesReferences• "Nuclear Fusion 'Put to the Test'" BBC NEWS 17 Feb. 2005. 19 Nov. 2007
<http://news.bbc.co.uk/2/low/science/nature/4270297.stm>.
• “Fusion Power." United Kingdom Atomic Energy Authority. 20 Nov. 2007. <http://www.fusion.org.uk/>.
• "JET." EFDA. 20 Nov. 2007. <http://www.jet.efda.org/index.html>.
• “Nuclear Fusion” howstuffworks.19 Nov 2007. Craig Freudenrich, Ph.D. <http://science.howstuffworks.com/fusion-reactor3.htm>
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