What is Fusion and Why We Need It
and Introduction to ITER
Mohamed Abdou (web: http://www.fusion.ucla.edu/abdou/)
Distinguished Professor of Engineering and Applied Science
Director, Center for Energy Science and Technology (CESTAR)
(http://www.cestar.seas.ucla.edu/)
Director, Fusion Science and Technology Center (http://www.fusion.ucla.edu/)
University of California, Los Angeles (UCLA)
Lecture 1 at the Xi’an Jiaotong University, Xi’an, China
August 2007
1
Outline
Lecture 1
• World Energy Scene
• What is fusion and Why we need it
• ITER
Lecture 2
• Fusion Nuclear Technology (FNT) and Blanket Concepts
– Principles
– Concepts
– Issues
• Framework and Facilities for FNT Development
– ITER Test Blanket
– CTF/VNS
2
Global Economics and Energy
Population
GDP
Energy Demand
Billions
Trillion (2000$)
10
80
Average Growth / Yr.
2000 - 2030
70
8
0.9%
60
MBDOE
350
2.8%
1.6%
300
250
50
6
4.7%
40
4
2
1.1%
OECD
0
1950
1990
0.4%
100
2030
2.2%
10
0
1950
2.4%
150
30
20
Non-OECD
200
0.7%
50
1990
2030
0
1950
1990
2030
3
Carbon dioxide levels over the last 60,000 years - we are
provoking the atmosphere!
Source:
University of Berne and
US National Oceanic and Atmospheric Administration
4
Energy Situation
•
The world uses a lot of energy
– Average power consumption = 13.6 TW (2.2 KW per person)
– World energy market ~ $3 trillion / yr (electricity ~ $1 trillion / yr)
•
The world energy use is growing
- to lift people out of poverty, to improve standard of living, and to
meet population growth
•
Climate change and debilitating pollution Concerns are on
the rise
– 80% of energy is generated by fossil fuels
– CO2 emission is increasing at an alarming rate
•
Oil supplies are dwindling
– Special problem for transportation sector (need alternative fuel)
5
Solving the Energy Problem Requires a
Diversified Portfolio and
Pursuing Several Approaches
•
Develop major new (clean) energy sources
(e.g. fusion)
•
Expand use of existing “clean” energy sources
(e.g. nuclear, solar, wind)
•
Develop technologies to reduce impact of fossil
fuels use (e.g. carbon capture and sequestration)
•
Improve energy efficiency
•
Develop alternate (synthetic) fuels for
transportation
6
Incentives for Developing Fusion
• Fusion powers the Sun and the stars
– It is now within reach for use on Earth
• In the fusion process lighter elements are “fused”
together, making heavier elements and producing
prodigious amounts of energy
• Fusion offers very attractive features:
– Sustainable energy source
(for DT cycle; provided that Breeding Blankets are successfully
developed)
– No emission of Greenhouse or other polluting gases
– No risk of a severe accident
– No long-lived radioactive waste
• Fusion energy can be used to produce electricity
and hydrogen, and for desalination
7
What is Nuclear Fusion?
•
•
Nuclear Fusion is the energy-producing process taking place in the core of
the Sun and stars
The core temperature of the Sun is about 15 million °C. At these
temperatures hydrogen nuclei fuse to give Helium and Energy. The
8
energy sustains life on Earth via sunlight
Energy Released by
Nuclear Reactions
• Light nuclei (hydrogen, helium) release
energy when they fuse (Nuclear Fusion)
• The product nuclei weigh less than the
parent nuclei
• Heavy nuclei (Uranium) release energy
when they split (Nuclear Fission)
• The product nuclei weigh less than the
original nucleus
9
Energy Released by Nuclear
Fusion and Fission
• Fusion reactions release much higher energies
than Fission reactions
10
Fusion Reactions
• Deuterium – from water
(0.02% of all hydrogen is heavy hydrogen or
deuterium)
• Tritium – from lithium
(a light metal common in the Earth’s crust)
Deuterium + Lithium → Helium + Energy
This fusion cycle (which has the fastest
reaction rate) is of interest for Energy
Production
11
Plasmas
• A Plasma is an ionised gas. A mixture of positive ions
and negative electrons with overall charge neutrality
• Plasmas constitute the 4th state of matter, obtained at
temperatures in excess of 100,000 degrees
• Plasmas conduct electricity and heat
12
Self-Sustaining or ‘Ignited’ Plasmas
• Deuterium – tritium fusion reaction:
D + T → 4He + n + Energy
The 4He nuclei (‘a’ particles) carry about 20% of the energy and
stay in the plasma. The other 80% is carried away by the neutrons
and can be used to generate steam.
Plasmas become Self-sustaining or Ignited when there is enough
a power to balance losses from the plasma
• In stars plasma particles (including a’s) are confined mainly by
gravity and high plasma densities achieved
• On Earth:
– hot dense plasmas can be confined in Magnetic fields (Magnetic
Confinement Fusion)
– superdense plasmas can be obtained by imploding solid deuteriumtritium pellets (Inertial Confinement Fusion)
13
Inertial Confinement
• Laser implosion of small (3mm diameter) solid deuterium–tritium
pellets produces fusion conditions
• Pressure generation
• Compression
Fuel is compressed by rocket-like blow off
200,000 million atmospheres in core
• Ignition and burn
– Peak compression fuel reaches 1000-10000 times liquid density for
extremely short time (10–11 seconds)
– Core is heated and ‘spark ignition’ occurs
14
Magnetic Confinement
• Magnetic fields cause charged particles to spiral
around field lines. Plasma particles are lost to the
vessel walls only by relatively slow diffusion across
the field lines
• Toroidal (ring shaped) system avoids plasma
hitting the end of the container
• The most successful Magnetic Confinement device
is the TOKAMAK (Russian for ‘Toroidal Magnetic
15
Chamber’)
The Tokamak:
A Transformer Device
16
How Large a Device?
• For fusion power to ignite a plasma:
– There has to be sufficient density of deuterium and tritium ions
(ni);
– The reacting ions have to be hot enough (Ti);
– The energy from the fusion a’s must be confined for long
enough (tE).
tE increases with the square of the device size
– a large machine is needed.
• The fusion triple product (niTitE) and the ion
temperature (Ti) must both be large enough (below a
certain temperature the fusion reaction probability is too
small)
pressure (niTi) ≥ 2 atmospheres
confinement time > 5 seconds
plasma ion temperature ≈ 100-200 Million °C
17
Controlling Impurities
• Fuel Impurities are a major threat to reactor
success
• Two primary sources of impurities exist:
– Helium “ash” from the fusion reaction
– Material impurities from plasma-wall interactions
• Impurities must be controlled since they:
– Radiate energy, and reduce the plasma temperature
– Dilute the fuel, thereby preventing ignition
• The “Magnetic Divertor” is a device for
controlling impurities.
18
Pumped Divertor in JET
• Impurities (C, Be) are produced by ion impact on target
19
and are ionised in the plasma and returned to target
The Deuterium-Tritium (D-T) Cycle
• World Program is focused on the D-T cycle (easiest to
ignite):
D + T → n + α + 17.58 MeV
• The fusion energy (17.58 MeV per reaction) appears as
Kinetic Energy of neutrons (14.06 MeV) and alphas (3.52
MeV)
• Tritium does not exist in nature! Decay half-life is 12.3 years
(Tritium must be generated inside the fusion system to
have a sustainable fuel cycle)
• The only possibility to adequately breed tritium is through
neutron interactions with lithium
– Lithium, in some form, must be used in the fusion system
20
Tritium Breeding
Li-6(n,alpha)t and Li-7(n,n,alpha)t Cross-Section
1000
Natural lithium contains
7.42% 6Li and 92.58% 7Li.
100
6Li
(n,a) t
Li-6(n,a) t
Li-7(n,na)t
10
6
Li  n  t  a  4.78MeV
7
Li  n  t  a  n  2.47 MeV
1
The 7Li(n;n’a)t reaction is a
threshold reaction and
requires an incident neutron
energy in excess of 2.8 MeV.
0.1
7Li
(n;n’a) t
0.01
1
10
100
1000
10
4
10
Neutron Energy (eV)
5
10
6
10
7
21
Shield
Blanket
Vacuum vessel
Radiation
Plasma
Neutrons
First Wall
Tritium breeding zone
Coolant for energy
conversion
Magnets
22
The world needs large scale
deployment of fusion by mid-century!
• 1950-2010
– The Physics of Plasmas
• 2010-2030
– The Physics of Fusion
– The “Fermi Demonstration” - Fusion-heated and sustained
• Q = (Ef / Einput )~10
• 2010-2040
– Fusion Nuclear Technology for Fusion
– DEMO by 2040
• 2050 ?
– Large scale deployment!
23
The World Fusion Program has a Goal for a
Demonstration Power Plant (DEMO) by ~2040
Poloidal Ring Coil
Cryostat
Coil Gap
Rib Panel
Blanket
Maint.
Port
Plasma
Vacuum
Vessel
Center Solenoid Coil
Toroidal Coil
24
JAEA DEMO Design
ITER
• The World is about to construct the next
step in fusion development, a device
called ITER
• ITER will demonstrate the scientific and
technological feasibility of fusion energy
for peaceful purposes
• ITER will produce 500 MW of fusion power
• Cost, including R&D, is 15 billion dollars
25
ITER Objectives
Programmatic
• Demonstrate the scientific and technological feasibility
of fusion energy for peaceful purposes.
Technical
• Demonstrate extended burn of DT plasmas, with steady
state as the ultimate goal.
• Integrate and test fusion technologies
• Demonstrate safety and environmental acceptability of
fusion.
26
ITER is a collaborative effort among Europe,
Japan, US, Russia, China, South Korea, and India
27
ITER Design - Main Features
Central
Solenoid
Outer Intercoil
Structure
Blanket
Module
Vacuum Vessel
Cryostat
Toroidal Field Coil
Port Plug (IC Heating
Poloidal Field Coil
Divertor
Machine Gravity Supports
Torus Cryopump
28
ITER Magnet System
The magnet system for ITER consists of 18 toroidal field (TF) coils, a central
solenoid (CS), six poloidal field (PF) coils and 18 correction coils (CCs).
The magnet system creates
a doughnut-shaped
magnetic field to confine
charged particles plasma.
29
ITER Blanket System
The basic function of the
blanket system is to provide
the main thermal and nuclear
shielding to the vessel and
external machine components.
FW Panel
Total number of
blanket modules: 421
Shield module
30
FW leg
Coaxial connector
ITER Divertor Cassette
(Total: 54 Cassettes in ITER)
The main function of the divertor system is to
exhaust the major part of the alpha particle power
as well as He and impurities from the plasma.
Dome
31
ITER Parameters
Total fusion power
Q = fusion power/auxiliary heating power
Average neutron wall loading
Plasma inductive burn time
Plasma major radius
Plasma minor radius
Plasma current (inductive, Ip)
Vertical elongation @95% flux surface/separatrix
Triangularity @95% flux surface/separatrix
Safety factor @95% flux surface
Toroidal field @ 6.2 m radius
Plasma volume
Plasma surface
Installed auxiliary heating/current drive power
500 MW (700MW)
≥10 (inductive)
0.57 MW/m2 (0.8 MW/m2)
≥ 300 s
6.2 m
2.0 m
15 MA (17.4 MA)
1.70/1.85
0.33/0.49
3.0
5.3 T
837 m3
678 m2
73 MW (100 MW)
32
Schedule
LICENSE TO
CONSTRUCT
ITER IO
2005
2006
2007
2008
TOKAMAK
ASSEMBLY STARTS
2009
2010
2011
2012
FIRST
PLASMA
2013
2014
2015
2016
EXCAVATE
Bid
Contract
TOKAMAK BUILDING
OTHER BUILDINGS
Construction License Process
First sector Complete VV
TOKAMAK ASSEMBLY
Install PFC
cryostat
MAGNET
Bid
Install CS
COMMISSIONING
Vendor’s Design
Contract
VESSEL
Complete
blanket/divertor
Bid
Contract
PFC
TFC CS
fabrication start
First sector
Last TFC
Last CS
Last sector
33
First D-T Burning Plasma in ITER in 2021
ITER Schedule
1st 10 yrs
Hybrid
operation
Phase
Flat top pulse length (s)
Equivalent number of
nominal burn pulses
Neutron fluence at TBM
FW (MW-y/m2) PER YR
1~3
4
5
6
7
8
9
10
H-H
D-D
D-T
D-T
D-T
D-T
D-T
D-T
400
400
400
 3000
3000
3000
100-200
0
1
750
1000
1500
2500
3000
3000
0.0
0.0
0.008
0.011
0.017
0.028
0.033
0.033
34
New Long-Pulse Confinement and Other Facilities
World-wide will Complement ITER
Japan (w/EU)
China
EAST
JT-60SA
(also LHD)
Europe
South Korea
W7-X
(also
JT-60SA)
India
SST-1
ITER Operations:
34% Europe
13% Japan
13% U.S.
10% China
10% India
10% Russia
10% S. Korea
KSTAR
U.S.
Being planned
Likely Fusion
Nuclear Technology
Testing Facility