ITER: The Journey to Nuclear Fusion Who, where, and when?
● European Union, Japan, Russia, China, India, Korea, USA
● Operate in 2018
● ~10 billion dollars Efficiency - % mass turned to energy
-8 ● 1.8 x 10 %, TNT, 3.8 calories/g -8 ● 5.3 x 10 %, 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!!!! 8 D-T reaction
4 ● D + T → He + n ; ΔE = 17.6 MeV
● requires temp > 40 million K
● optimal temp ~ 10 keV – 100 million K ● requires tritium breeding (lithium) D-D reaction
3 ● D + D → T + p (or → He + 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/P loss 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 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
23 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 N of gallons of gasoline in the ocean A – 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
24 Hey, oil does float on water!
25 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)
26 Backup slides
27 Plasma Instabilities
28 Plasma instabilities
29 Z-pinch and mirror
30 Fusion basics
1 2 3 ● H = H = p, H = D, H = 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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