Nuclear FusionEnergy

Rishi Gohil

ChE 379: Energy Technology and PolicyDr. Thomas EdgarFall 2007

Nuclear Fusion PrincipleEnergy 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 earthAt high temperature, the gas mixture forms a plasma (hot, electrically charged gas)

Nuclear FusionThis reaction releases 17.6 MeV of energy. No limit on amount of fusion that can occur (unlike fission).

Requirements for Fusion ReactionPlasma Temperature:100-200 million Kelvin Needed to overcome natural positive repulsive forces of plasma ionsEnergy Confinement Time: 4-6 secondsThe 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-3Large density needed because number of fusion reactions per unit volume is roughly proportional to the square of the density

Plasma Toroid (Tokamak)

Flow of Energy

ChallengesCurrent research in controlling high temperature plasmaHow to heat plasma to >100 million deg C.How to confine such a plasmaHow to sustain the reactions.

AdvantagesAbundant fuels: Deuterium (from water), Tritium (from Lithium) and Lithium (plentiful on Earths crust).Inherently safe: Because conditions for reaction are stringent and small amounts of fuel usedEnvironmentally safe: No greenhouse gas emissions and byproduct of reaction is Helium.

JET (Joint European Torus)JET: Worlds largest nuclear fusion research facility

Fusion ReactorEU to build pilot fusion reactor, Iter.Cost: 4.57 Billion EURO (2000 prices) over 10 yrsLife: 35 yearsCountries Involved: 7Design: reactions occur in 100 million degree gas (plasma) suspended in donut shaped magnetic field.Problems: Sustained and stable reactionsPotential: 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.

Iter Timeline

References"Nuclear Fusion 'Put to the Test'" BBC NEWS 17 Feb. 2005. 19 Nov. 2007 .

Fusion Power." United Kingdom Atomic Energy Authority. 20 Nov. 2007. .

"JET." EFDA. 20 Nov. 2007. .

Nuclear Fusion howstuffworks.19 Nov 2007. Craig Freudenrich, Ph.D.