THE PATH TOWARD MAGNETIC
FUSION ENERGY DEMONSTRATION
AND THE ROLE OF ITER
Mohamed Abdou
Distinguished Professor of Engineering and Applied Science
Director, Center for Energy Science and Technology (CESTAR)
Director, Fusion Science and Technology Center
University of California, Los Angeles (UCLA)
web: http://www.fusion.ucla.edu/abdou/
Opening Invited Lecture
7th PAMIR International Conference on Fundamental and Applied MHD
8-12 September, 2008 Presqu´île de Giens - France
Fusion and ITER: Outline
•
•
•
•
What is fusion and why do we need it?
ITER
Fusion Nuclear Science and Technology (FNST)
Pathway for FNST & Fusion Development
– Framework for FNST Development
– ITER Test Blanket
– Need for new facilities FNF (CTF/VNS)
• The Central Role and Impact of magnetic field on many
aspects of the (magnetic) Fusion Energy System (if time
permits)
2
What is fusion?
 two light nuclei combining to form a heavier nuclei
(the opposite of nuclear fission). Fusion powers the Sun and Stars
Deuterium
mc2
E=
17.6 MeV
Tritium
Neutron
80% of energy
release
(14.1 MeV)
Used to breed
tritium and close
the DT fuel cycle
Li + n → T + He
Li in some form must be
used in the fusion
system
Helium
20% of energy release
(3.5 MeV)
Illustration from DOE brochure
 Deuterium and tritium is the easiest,
attainable at lower plasma temperature,
because it has the largest reaction
rate and high Q value.
 The World Program is focused
on the D-T Cycle
3
077-05/rs
Incentives for Developing Fusion
 Sustainable energy source
(for DT cycle: provided that Breeding Blankets are
successfully developed and tritium self sufficiency
conditions are satisfied)
 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.
4
Fusion Research is about to transition from Plasma
Physics to Fusion Science and Engineering
• 1950-2010
– The Physics of Plasmas
• 2010-2035
– The Physics of Fusion
– Fusion Plasmas-heated and sustained
• Q = (Ef / Einput )~10
• ITER (magnetic fusion) and NIF (inertial fusion)
• 2010-2040 ?
– Fusion Nuclear Science and Technology for Fusion
– DEMO by 2040?
• > 2050 ?
– Large scale deployment!
5
The World Fusion Program has a Goal for a
Demonstration Power Plant (DEMO) by ~2040(?)
Plans for DEMO are based on Tokamaks
Poloidal Ring Coil
Cryostat
Coil Gap
Rib Panel
Blanket
Maint.
Port
Plasma
Vacuum
Vessel
Center Solenoid Coil
Toroidal Coil
(illustration is from 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.
•
ITER is a collaborative effort among Europe, Japan,
US, Russia, China, South Korea, and India. ITER
construction site is Cadarache, France.
7
ITER is a reactor-grade tokamak plasma physics
experiment - a huge step toward fusion energy






Will use D-T and produce neutrons
500MW fusion power, Q=10
Burn times of 400s
Reactor scale dimensions
Actively cooled PFCs
Superconducting magnets
~29 m
~15 m
By Comparison,
JET
 ~10 MW
 ~1 sec
 Passively
Cooled
JET
ITER
ITER Magnet System
• 18 Toroidal Field (TF) coils
produce the toroidal magnetic
field to confine and stabilize
the plasma
− Superconducting,
Nb3Sn/Cu/SS
− Max. field: 11.8T
• 6 Poloidal Field (PF) coils
position and shape the
plasma
− Superconducting,
NbTi/Cu/SS
− Max. field: 6T
• Central Solenoid (CS)
coil induces current in
the plasma
• 18 Correction coils correct error fields
− Superconducting, NbTi/Cu/SS
− Max. field < 6T
TF coil case provides main
structure of the magnet
system and machine core
Stored energy in ITER magnetic field is large ~ 1200 MJ
Equivalent to a fully loaded 747 moving at take off speed 265 km/h
− Superconducting,
Nb3Sn/Cu/alloy908
−Max. field: 13.5T
9
First D-T Burning Plasma in ITER in 2021 (2025?)
ITER Schedule
1st 10 yrs
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
10
New Long-Pulse Confinement and Other Facilities
Worldwide 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
The primary functions of the blanket are to provide for:
Power Extraction & Tritium Breeding
Shield
Blanket
Vacuum vessel
Radiation
DT
Plasma
Neutrons
First Wall
Tritium breeding zone
Magnets
Coolant for energy
conversion
12
Blanket Concepts
A.
(many concepts proposed worldwide)
Solid Breeder Concepts
– Solid Breeder: Lithium Ceramic (Li2O, Li4SiO4, Li2TiO3, Li2ZrO3)
– Coolant: Helium or Water
B.
Liquid Breeder Concepts
a) Liquid metal (high conductivity, low Pr): Li, or 83Pb 17Li
b) Molten salt (low conductivity, high Pr): Flibe (LiF)n · (BeF2),Flinabe (LiF-BeF2-NaF)
B.1.
Self-Cooled
– Liquid breeder is circulated at high enough speed to also serve as coolant
B.2.
Separately Cooled
– A separate coolant is used (e.g., helium)
– The breeder is circulated only at low speed for tritium extraction
B.3.
Dual Coolant
– FW and structure are cooled with separate coolant (He)
– Breeding zone is self-cooled
All these concepts have their own feasibility & attractiveness issues.
Liquid metal concepts are potentially more attractive, but feasibility issues
13
arise because of interactions with the magnetic field.
Flows of electrically conducting coolants will experience
complicated MHD effects in the magnetic fusion environment
3-component magnetic field and complex geometry
– Motion of a conductor in a magnetic field produces an EMF that can
induce current in the liquid. This must be added to Ohm’s law:
j   (E  V  B )
– Any induced current in the liquid results in an additional body force
in the liquid that usually opposes the motion. This body force must
be included in the Navier-Stokes equation of motion:
V
1
1
 (V  )V   p   2 V  g  j  B
t


– For liquid metal coolant, this body force can have dramatic impact
on the flow: e.g. enormous MHD drag, highly distorted velocity
profiles, non-uniform flow distribution, modified or suppressed
turbulent fluctuations.
Dominant impact on LM design.
Challenging Numerical/Computational/Experimental Issues
14
MHD Characteristics of Fusion
Liquid Breeder Blanket Systems
A perfectly insulated “WALL”
can solve the problem, but is it
practical?
Self-Cooled liquid Metal
Blankets are NOT feasible now
because of MHD Pressure Drop
Conducting walls
Insulated walls
Lines of current enter the low
resistance wall – leads to very
high induced current and high
pressure drop
1
0.8
0.6
0.4
1
0.8
0.6
0.4
0.2
0.2
0
0
-0.2
-0.2
All current must close in the
liquid near the wall – net drag
from jxB force is zero
-0.4
-0.6
-0.8
-1
•
•
-0.6
-0.8
-1
-1
-1
•
-0.4
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
Net JxB body force p =
where c = (tw w)/(a )
For high magnetic field and high
speed (self-cooled LM concepts
in inboard region) the pressure
drop is large
The resulting stresses on the
wall exceed the allowable stress
for candidate structural
materials
•
cVB2
•
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
Perfect insulators make the net
MHD body force zero
But insulator coating crack
tolerance is very low (~10-7).
–
•
-0.8
It appears impossible to develop
practical insulators under fusion
environment conditions with large
temperature, stress, and radiation
gradients
Self-healing coatings have been
proposed but none has yet been
found (research is on-going)
No self-cooled blanket option. Li/V is not a candidate now.
16
Separately-cooled LM Blanket
Example: PbLi Breeder/ helium Coolant with RAFM
Module box
 EU mainline blanket design
(container & surface
 All energy removed by separate
heat flux extraction)
Helium coolant
 The idea is to avoid MHD issues.
But, PbLi must still be circulated to extract
tritium
Breeder cooling
unit (heat extraction
from PbLi)
 ISSUES:
– Low velocity of PbLi leads to high
tritium partial pressure , which leads to
tritium permeation (Serious Problem)
– Tout limited by PbLi compatibility with
RAFM steel structure ~ 500C
(and also by limit on Ferritic, ~550C)
 Possible MHD Issues :
– MHD pressure drop in the inlet
manifolds
– B- Effect of MHD buoyancy-driven flows
on tritium transport
Stiffening structure
Drawbacks: Tritium
Permeation and limited
thermal efficiency
(resistance to accidental in-box
pressurization i.e He leakage)
He collector system
(back)
17
Pathway Toward Higher Temperature through Innovative
Designs with Current Structural Material (Ferritic Steel):
Dual Coolant Lead-Lithium (DCLL) FW/Blanket Concept
 First wall and ferritic steel structure
cooled with helium
 Breeding zone is self-cooled
 Structure and Breeding zone are
separated by SiCf/SiC composite
flow channel inserts (FCIs) that
 Provide thermal insulation to
decouple PbLi bulk flow
temperature from ferritic steel
wall
 Provide electrical insulation to
reduce MHD pressure drop in
the flowing breeding zone
DCLL Typical Unit Cell
FCI does not serve structural function
Pb-17Li exit temperature can be significantly higher than the
operating temperature of the steel structure  High Efficiency
18
High pressure drop is only one of the MHD issues for LM
blankets; MHD heat and mass transfer are also of great
importance!
Instabilities and 3D MHD effects in complex
detailed geometry and configuration with
magnetic and nuclear fields gradients
have major impact.
FCI overlap gaps act
as conducting breaks
in FCI insulation
• Unbalanced pressure drops (e.g. from
insulator cracks) leading to flow control and
channel stagnation issues
• Unique MHD velocity profiles and instabilities
affecting transport of mass and energy
Accurate Prediction of MHD Heat &Mass
Transfer is essential to addressing
important issues such as:
• thermal stresses,
• temperature limits,
• failure modes for structural and
functional materials,
• thermal efficiency, and
• tritium permeation.
and hence disturb current
flow and velocity, and
redistribute energy
Courtesy of Munipalli et al.
(Ha=1000; Re=1000; =5 S/m,
cross-sectional dimension expanded 10x)
19
077-05/rs
Fusion Nuclear Technology (FNT)
Fusion Power & Fuel Cycle Technology
FNT Components from the edge of the
Plasma to TF Coils (Reactor “Core”)
1. Blanket Components (includ. FW)
2. Plasma Interactive and High Heat Flux
Components
a. divertor, limiter
b. rf antennas, launchers, wave guides, etc.
3. Vacuum Vessel & Shield Components
• The location of the Blanket inside the
vacuum vessel is necessary but has major
consequences:
a- many failures (e.g. coolant leak)
require immediate shutdown
b- repair/replacement take long time
20
Challenging
Fusion Nuclear Science & Technology Issues
1. Tritium Supply &
Tritium Self-Sufficiency
2. High Power Density
3. High Temperature
4. MHD for Liquid Breeders / Coolants
5. Tritium Control (Permeation)
6. Reliability / Maintainability / Availability
7. Testing in Fusion Facilities
21
Testing Blankets in the fusion environment is Necessary: Combined effects of
Radiation, Surface Heat flux, Nuclear Heating & gradients, Magnetic field &
gradients, etc can be reproduced only in a fusion facility.
Example: MHD flow & FCI behavior are highly coupled in a complex fusion environment
 PbLi flow is strongly influenced by MHD interaction
with plasma confinement field and buoyancy-driven
convection driven by spatially non-uniform
volumetric nuclear heating
 This MHD flow and convective heat
transport processes determine the
temperature and thermal stress of SiC FCI
 The FCI temperature and thermal stress coupled
with early-life radiation damage effects in ceramics
affect deformation, cracking, and properties of the
FCI
Courtesy of S.
Smolentsev
FCI temperature, stress and
deformation
 Cracking and movement of the FCIs will strongly
influence MHD flow behavior by opening up new
conduction paths that change electric current
profiles
Resulting temperature field also strongly couples to phenomena
such as tritium transport and permeation, and corrosion
22
22
077-05/rs
R&D Tasks to be Accomplished Prior to Demo
1) Plasma
- Confinement/Burn
- Disruption Control
2) Plasma Support Systems
- Superconducting Magnets
- Current Drive/Steady State
- Edge Control
- Fueling
- Heating
- Diagnostics
3) Fusion Nuclear Science and Technology
- Nuclear Components and Materials:
Blanket/FW, Divertors, rf Launchers, etc.
4) Systems Integration
Where Will These Tasks be Done?!
• Burning Plasma Facility (ITER) and other plasma devices will address 1, 2, & much of 4
• Where Will Fusion Nuclear Science and Technology (FNST) be developed?
(ITER alone?, another device?, both?)
23
THREE Stages of FNST Testing in Fusion Facilities
are Required Prior to DEMO
Fusion “Break-in” &
Scientific Exploration
Engineering Feasibility
& Performance
Verification
Component Engineering
Development &
Reliability Growth
Stage I
Stage II
Stage III
0.1 – 0.3 MW-y/m2
1 - 3 MW-y/m2
> 4 - 6 MW-y/m2
1-2 MW/m2
steady state or long pulse
COT ~ 1-2 weeks
1-2 MW/m2
steady state or long burn
COT ~ 1-2 weeks
 0.5 MW/m2, burn > 200 s
Sub-Modules/Modules
Modules
D
E
M
O
Modules/Sectors
- ITER is designed to fluence < 0.3MW-y/m2. ITER can do only Stage I
- Where to do Stages II & III ?
24
ITER Provides Substantial Hardware Capabilities
for Testing of Blanket System
TBM System (TBM + T-Extrac,
Heat Transport/Exchange…)
Bio-shield
A PbLi loop
Transporter located in
the Port Cell Area
2.2 m
ITER has allocated 3
ITER equatorial ports
(1.75 x 2.2 m2) for TBM
testing
Each port can
accommodate only 2
modules (i.e. 6 TBMs max)
He pipes to
TCWS
Equatorial Port
Plug Assy.
Vacuum Vessel
TBM
Assy
Port
Frame
Fluence in ITER is limited to 0.3MW-y/m2 . We have to
build another facility, for FNST development
25
The issue of external tritium supply is serious and has major
implications on FNST (and Fusion) Development Pathway
Production & Cost:
CANDU Reactors: 27 kg from over 40 years,
$30M/kg (current)
Fission reactors: 2–3 kg/year
$84M-$130M/kg (per DOE Inspector General*)
*www.ig.energy.gov/documents/CalendarYear2003/ig-0632.pdf
 A Successful ITER will exhaust most
of the world supply of tritium, but
5-10 kg will be needed to start one DEMO
(one DEMO? Other countries will compete for tritium!)
 Any future long pulse burning plasma device
will need tritium breeding technology
 The availability and cost of external tritium
supply is a serious issue for FNST
development
 FNST engineering development and
reliability growth stages must be done in a
small fusion power device to minimize
tritium consumption (only stage I fusion
break-in can be done in ITER)
Projected Ontario (OPG) Tritium Inventory (kg)
Tritium Consumption in Fusion is HUGE! Unprecedented!
55.6 kg per 1000 MW fusion power per year
30
Tritium decays at
5.47% per year
CANDU
Supply
w/o Fusion
25
20
15
10
1000 MW Fusion
10% Avail,
TBR 0.0
5
ITER-FEAT
(2004 start)
See Table S/Z
0
1995 2000 2005
2010 2015 2020 2025 2030 2035 2040 2045
Year
Tritium Breeding Blankets must be developed in
the near term to solve the serious issue of
external tritium supply. We cannot wait very
long for blanket development.
26
Fusion Nuclear Facility (FNF)
• The idea of FNF (also called VNS, CTF) is to build a small size, low
fusion power DT plasma-based device in which Fusion Nuclear
Science and Technology (FNST) experiments can be performed in the
relevant fusion environment:
1- at the smallest possible scale, cost, and risk, and
2- with practical strategy for solving the tritium consumption and
supply issues for FNST development.
In MFE: small-size, low fusion power can be obtained in a low-Q
(driven) plasma device, with normal conducting Cu magnets
• There are at least TWO classes of Design Options for FNF:
- Tokamak with Standard Aspect Ratio, A ~2.8-4
- ST with Small Aspect Ratio, A~ 1.5
27
Example of Fusion Nuclear Facility (FNF) Device Design Option :
Standard Aspect Ratio (A=3.5) with demountable TF coils (GA design)
• High elongation, high
triangularity double
null plasma shape
for high gain, steadystate plasma
operation
• Plate constructed copper TF Coils which enables…
• TF Coil joint for complete disassembly and maintenance
• OH Coil wound on the TF Coil to maximize Volt-seconds
Another Option for FNF Design: Small Aspect Ratio (ST)
Smallest power and size, Cu TF magnet, Center Post
(Example from Peng et al, ORNL) R=1.2m, A=1.5, Kappa=3, Pfusion=75MW
WL [MW/m2]
R0 [m]
1.20
A
1.50
Kappa
3.07
Qcyl
4.6
Bt [T]
1.13
Ip [MA]
3.4
3.7
2.0
3.0
2.18
8.2
3.8
Beta_N
10.1
5.9
Beta_T
0.14
0.18
0.28
ne [1020/m3]
0.43
1.05
1.28
fBS
0.58
0.49
0.50
Tavgi [keV]
5.4
10.3
13.3
Tavge [keV]
3.1
6.8
8.1
1.5
HH98
0.50
2.5
3.5
Paux-CD [MW]
15
31
43
ENB [keV]
100
239
294
PFusion [MW]
7.5
75
150
Q
T M height [m]
1.64
T M area [m2]
14
Blanket A [m2]
66
Fn-capture
ST-VNS Goals, Features, Issues, FNST Mtg, UCLA, 8/12-14/08
1.0
0.1
0.76
29
Summary
• Fusion is the most promising long-term energy option
– renewable fuel, no emission of greenhouse gases, inherent safety
• 7 nations are about to construct ITER to demonstrate the
scientific and technological feasibility of fusion energy.
– ITER will have first DT plasma in ~2025
• The most challenging Phase of Fusion development still lies
ahead. It is the development of Fusion Nuclear Science and
Technology (FNST)
– ITER, limited fluence, addresses only initial Stage of FNST testing
– A Fusion Nuclear Facility (FNF) is required to develop FNST.
– FNF must be small size, small power DT, driven plasma with Cu magnets
• Magnets and magnetic field interactions are a major part of
the magnetic fusion energy system
– Superconducting magnets are used in ITER and essential for Power
Reactors. But Normal Cu magnets with special joints and features are
needed for FNF
– LM Blankets are most promising, but their potential is limited by MHD
effects. Innovative concepts must continue to be proposed and investigated
30