ITER: The Journey to Nuclear Fusion

Who, where, and when?

● European Union, Japan, Russia, China, India, Korea, USA

● Cadarache, France● Operate in 2018● ~10 billion dollars

Efficiency - % mass turned to energy

● 1.8 x 10-8 %, TNT, 3.8 calories/g

● 5.3 x 10-8 %, gasoline, 11.5 calories/g● 0.09%, U-235 fission● 0.38%, D-T fusion● 5%-42%, Gravitational accretion friction● <20%, Penrose process● typically 10%, Blandford-Znajek process

– can be >100%

Supply and demand

● At the 2005 worldwide energy consumption rate, how long would each fuel source last humanity?

● natural gas – 100 years● oil – 220 years● coal – 540 years● uranium – 2000 years● lithium (D-T) – 6200 years● deuterium – Take a guess!

Supply and demand

● At the 2005 worldwide energy consumption rate, how long would each fuel source last humanity?

● natural gas – 100 years● oil – 220 years● coal – 540 years● uranium – 2000 years● lithium (D-T) – 6200 years● deuterium – 20 billion years!!! !

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D-T reaction

● D + T → 4He + n ; ΔE = 17.6 MeV● requires temp > 40 million K● optimal temp ~ 10 keV

– 100 million K

● requires tritium breeding (lithium)

D-D reaction

● D + D → T + p (or → 3He + n) ; ΔE ~ 3.7 MeV● Temp ~ 15 keV

● Requires 30x energy confinement of D-T process

● Power produced is 68 times less than D-T

● Doesn't require tritium breeding (lithium sources)

● Greater energy supply● cycle of 4 reactions possible:

– 6 D → 4 4He + 2 p + 2 n + 43.2 MeV

Advantages of fusion power

● limitless supply● no greenhouse gases● suitable for large scale power production● relatively small amounts of radioactive waste on

relatively short time scales (<100 years)● no transport of radioactive material● no possibility for runaway reaction

Lawson criterion

● Ignition: Plasma self heating > power lost

● n = density, τ – confinement time, E/Ploss

Triple product

Tokamak

Heating plasma

Heating plasma

● Ohmic heating (current through the plasma) only works to about 10 million K

● neutral heating – injecting accelerated neutrals● radio frequency heating – tuned to cyclotron

frequencies● alpha heating (self heating) works above about 100

million K

Breeding

● Li-6 + n → T + He-4 + 4.8 MeV● Li-7 + n + 2.5 MeV → T + He-4 + n● needs neutron source● depends on supply of lithium

Objectives

● To produce more energy than it consumes– Q = power out / power in

– current record is Q = 0.65, by JET in 1997

– the goal is Q = 10 (burst), Q > 5 (steady state)

● Test key technologies– superconducting magnets, remote handling, material

endurance

● Breeding its own tritium– eliminating the dependence on fission reactors

Main parameters

● Plasma Major Radius 6.2 m● Plasma Minor Radius 2.0 m● Plasma Volume 840 m3● Plasma Current 15.0 MA● Toroidal Field on Axis 5.3 T● Fusion Power 500 MW● Burn Flat Top >400 s● Power Amplification >10x

Material problems

● high flux of 14 MeV neutrons● degrades materials● radioactive for a few decades● austenitic stainless steel currently used

– replace inner surface every few years

Timeline

● now – excavating the construction site● 2009 – begin construction● 2012 – tokamak assembly● 2016 – first plasma● 2020 – first fusion● run for a total of 20 years● (approx) 5 + 25 + 5 = 40 years of decommissioning

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What's next?

● DEMO, the demonstration fusion power plant ● 2 GW on a continual basis, Q > 25● 15% larger, 30% higher density● Plan: build in 2024 (Japan)● Start in 2033

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Fun facts

● 1 gallon of seawater contains as much energy in deuterium as 300 gallons of gasoline

● 1 Tb of water = 1 gallon of gasoline

● ~1/3 NA of gallons of gasoline in the ocean

– 1 gallon of water ~= 8000 miles in a car, here to New York and back easily, probably can make it there again

● All deuterium is from minutes after the Big Bang

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Hey, oil does float on water!

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Discussion suggestions

● Funding● Instabilities● Other fuel cycles

– aneutronic fusion – less mess, harder to do

– He reactions, requires source, moon?

– p + B -> 3 4He (600 keV, 6.6 GK)

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Backup slides

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Plasma Instabilities

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Plasma instabilities

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Z-pinch and mirror

Fusion basics

●1H = H = p, 2H = D, 3H = T

● D-T reaction:

– D + T → 4He + n ; ΔE = 17.6 MeV

– Temp ~ 10 keV

● D-D reaction:

– D + D → T + p (or → 3He + n) ; ΔE = ~3.7 MeV

– Temp ~ 15 keV

– Requires energy confinement 30x D-T process

– power produced 68 times less than D-T

– doesn't require tritium breeding (lithium sources)

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