Role of Fusion Energy in
the 21st Century
Farrokh Najmabadi
Prof. of Electrical Engineering
Director of Center for Energy Research
UC San Diego
Lehigh University
Physics Department Colloquium
April 26, 2012
UCSD Center for Energy Research
 Plasma Physics & Fusion Energy
 Solar Energy (renewable) forecasting & integration
 Fuel Cells









Staff
Graduate Students (PhD)
Paid Student Researchers (non-Degree)
Annual Research Funding (09-10)
Number of Active Grants (09-10)
Total Funding received (06-10)
Number of Journal publications (06-10)
Number of Conference papers (06-10)
Professional Society Awards
90
25
15
$8.5M*
49
$40M
262
163
12
The Energy Challenge
Scale:
1 EJ = 1018 J = 24 Mtoe
1TW = 31.5 EJ/year
World energy use ~ 450 EJ/year
~ 14 TW
Energy use increases with
Economic Development
400
US
Primary Energy per capita (GJ)
350
300
Australia
250
Russia
200
France
Japan
UK
S. Korea
150
Ireland
100
Malaysia
Mexico
50
China
0
0 India
Greece
Brazil
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
GDP per capita (PPP, $2000)
 With industrialization of emerging nations, energy use is expected to
grow ~ 4 fold in this century (average 1.6% annual growth rate)
Data from IEA World Energy Outlook 2006
Quality of Life is strongly correlated
to energy use.
HDI: (index reflecting life expectancy at birth + adult literacy &
school enrolment + GNP (PPP) per capita)
 Typical goals: HDI of 0.9 at 3 toe per capita for developing countries.
 For all developing countries to reach this point, would need world energy
use to double with today’s population, or increase 2.6 fold with the 8.1
billion expected in 2030.
World Energy Demand (Mtoe)
World Primary Energy Demand is
expect to grow substantially
 Data from IAE World Energy Outlook 2006 Reference (Red) and
Alternative (Blue) scenarios.
 World population is projected to grow from 6.4B (2004) to 8.1B (2030).
 Scenarios are very sensitive to assumption about China.
Energy supply will be dominated by
fossil fuels for the foreseeable future
’04 – ’30 Annual Growth
Rate (%)
M toe
18,000
16,000
14,000
12,000
10,000
Other
Renew ables
6.5
Biomass &
w aste
1.3
Hydro
2.0
Nuclear
0.7
Gas
2.0
Oil
1.3
Coal
1.8
8,000
6,000
4,000
2,000
0
1980
2004
2010
2015
Source: IEA World Energy Outlook 2006 (Reference Case), Business as Usual (BAU) case
2030
Total
1.6
Technologies to meet the energy
challenge do not exist
 Improved efficiency and lower demand

Huge scope but demand has always risen faster due to long turn-over
time.
 Renewables

Intermittency, cost, environmental impact.
 Carbon sequestration

Requires handling large amounts of C (Emissions to 2050
=2000Gtonne CO2)
 Fission

Fuel cycle and waste disposal
 Fusion

Probably a large contributor in the 2nd half of the century 
Energy Challenge: A Summary
 Large increases in energy use is expected.
 IEA world Energy Outlook indicate that it will require increased use
of fossil fuels

Air pollution & Global Warming

Will run out sooner or later
 Limiting CO2 to 550ppm by 2050 is an ambitious goal.

USDOE: “The technology to generate this amount of emission-free
power does not exist.”

IEA report: “Achieving a truly sustainable energy system will call for
radical breakthroughs that alter how we produce and use energy.”
 Public funding of energy research is down 50% since 1980 (in real
term). World energy R&D expenditure is 0.25% of energy market of
$4.5 trillion.
Most of public energy expenditures
is in the form of subsidies
Energy Subsides (€28B) and R&D (€2B) in the EU
Renewables 18%
Fission 6%
Coal
44.5%
Fusion 1.5%
Oil and gas
30%
Slide from C. Llewellyn Smith, UKAEA
Source : EEA, Energy subsidies in the
European Union: A brief overview, 2004.
Fusion and fission are displayed
separately using the IEA governmentR&D data base and EURATOM 6th
framework programme data
Fission (seeking a
significant fraction of
World Energy
Consumption of 14TW)
Nuclear power is already a large
contributor to world energy supply
 Nuclear power provide 8% of world total energy demand
(20% of US electricity)
 Operating reactors in 31 countries



438 nuclear plants generating 353 GWe
Half of reactors in US, Japan, and France
104 reactor is US, 69 in France
US Nuclear Electricity (GWh)
 30 New plants in 12 countries under construction
1000
 No new plant in US for more
800
than two decades
 Increased production due to
higher availability
600
400
 30% of US electricity growth
 Equivalent to 25 1GW plants
 Extended license for many plants
200
0
1990
1994
2000
2001
2002
Evolution of Fission Reactors
Challenges to Long-term viability of
fission
 Economics:


Reduced costs
Reduced financial risk (especially licensing/construction time)
 Safety


Protection from core damage (reduce likelihood)
Eliminate offsite radioactive release potential
 Sustainability



Efficient fuel utilization
Waste minimization and management
Non-proliferation
 Reprocessing and Transmutation
 Gen IV Reactors
Fusion: Looking into the
future
ARIES-AT tokamak Power plant
Brining a Star to Earth
D + T  4He (3.5 MeV) + n (14 MeV)
T
n +
6Li

4He
(2 MeV)
+ T (2.7 MeV)
n
D + 6Li  2 4He + 3.5 MeV (Plasma) + 17 MeV (Blanket)
 DT fusion has the largest cross section and lowest temperature
(~100M oC). But, it is still a high-temperature plasma!
 Plasma should be surrounded by a Li-containing blanket to
generate T. Or, DT fusion turns its waste (neutrons) into fuel!
 Through careful design, only a small fraction of neutrons are
absorbed in structure and induce radioactivity.
 For liquid coolant/breeders (e.g., Li, LiPb), most of fusion energy is
directly deposited in the coolant simplifying energy recovery
 Practically no resource limit (1011 TWy D; 104 (108) TWy 6Li)
Fusion Energy Requirements:
 Confining the plasma so that alpha particles sustain
fusion burn

Lawson Criteria: ntE ~ 1021 s/m3
 Heating the plasma for fusion reactions to occur

to 100 Million oC (routinely done in present experiments)
 Optimizing plasma confinement device to minimize the cost

Smaller devices

Cheaper systems, e.g., lower-field magnets (MFE) or lowerpower lasers (IFE)
 Extracting the fusion power and breeding tritium

Co-existence of a hot plasma with material interface

Developing power extraction technology that can operate in
fusion environment
Two Approaches to Fusion Power –
1) Inertial Fusion
 Inertial Fusion Energy (IFE)



Fast implosion of high-density DT capsules by laser or particle beams
(~30 fold radial convergence, heating to fusion temperature).
A DT burn front is generated, fusing ~1/3 of fuel (to be demonstrated in
National Ignition Facility in Lawrence Livermore National Lab).
Several ~300 MJ explosions per second with large gain (fusion
power/input power).
Two Approaches to Fusion Power –
2) Magnetic Fusion
 Magnetic Fusion Energy (MFE)



Particles confined within a “toroidal magnetic bottle” for 10’s km
and 100’s of collisions per fusion event.
Strong magnetic pressure (100’s atm) to confine a low density but
high pressure (10’s atm) plasma.
At sufficient plasma pressure and “confinement time”, the 4He
power deposited in the plasma sustains fusion condition.
 Rest of the Talk is focused on MFE
Plasma behavior is dominated by
“collective” effects
 Pressure balance (equilibrium) does not guaranty stability.

Example: Interchange stability
Fluid Interchange Instability
Outside part of torus
inside part of torus
 Impossible to design a “toroidal magnetic
bottle” with good curvatures everywhere.
 Fortunately, because of high speed of
particles, an “averaged” good curvature is
sufficient.
Tokamak is the most successful
concept for plasma confinement
DIII-D, General Atomics
Largest US tokamak
R=1.7 m
 Many other configurations
possible depending on the value
and profile of “q” and how it is
generated (internally or externally)
T3 Tokamak achieved the first high
temperature (10 M oC) plasma
0.06 MA
Plasma Current
R=1 m
JET is currently the largest tokamak
in the world
ITER Burning plasma experiment (under construction)
R=3 m
R=6 m
Progress in plasma confinement
has been impressive
Fusion triple product
n (1021 m-3) t(s) T(keV)
ITER Burning plasma experiment
500 MW of fusion Power for
300s
Construction has started in
France
Large amount of fusion power has
also been produced
ITER Burning plasma experiment
DT Experiments
DD Experiments
Fusion Energy Requirements:
 Confining the plasma so that alpha particles sustain fusion
burn

Lawson Criteria: ntE ~ 1021 s/m3
 Heating the plasma for fusion reactions to occur

to 100 Million oC (routinely done in present experiments)
 Optimizing plasma confinement device to minimize the cost

Smaller devices

Cheaper systems, e.g., lower-field magnets (MFE) or lowerpower lasers (IFE)
 Extracting the fusion power and breeding tritium
ITER and Satellite tokamaks (e.g., JT60-SU in Japan)
 Developing power extraction technology that can operate in fusion
shouldenvironment
demonstrate operation of a fusion plasma (and
its support
technologies)
atwith
thematerial
power
plant scale.
 Co-existence
of a hot plasma
interface
ITER Device History
1988-1990
EU, Japan, USSR, and US conducted the
Conceptual Design Activity
1992
Engineering Design Activity (EDA) Started
1998
Initial EDA ended. US urged rescoring to
reduce cost
1998
US withdraws from ITER at Congressional Direction.
EU, Japan, RF pursue a lower cost design
2001
EDA ends
2003
US, Korea, and China join ITER
2006
Agreement on ITER Site
2009
Construction of long-lead time components started
2017?
First Plasma
2026?
Full power DT experiments
We have made tremendous progress
in optimizing fusion plasmas
 Substantial improvement in
plasma performance though
optimization of plasma shape,
profiles, and feedback.




Achieving plasma stability at high
plasma pressure.
Achieving improved plasma
confinement through suppression of
plasma turbulence, the “transport
barrier.”
Progress toward steady-state operation
through minimization of power needed
to maintain plasma current through
profile control.
Controlling the boundary layer between
plasma and vessel wall to avoid
localized particle and heat loads.
ITER and satellite tokamaks will provide the
necessary data for a fusion power plant
DIII-D
Simultaneous
Major toroidal radius (m)
1.7
Plasma Current (MA)
2.25
Magnetic field (T)
2
Electron temperature (keV)
7.5*
Ion Temperature (keV)
18*
Density (1020 m-3)
1.0*
Confinement time (s)
0.4
Normalized confinement, H89
4.5
b (plasma/magnetic pressure)
6.7%
Normalized b
3.9
Fusion Power (MW)
Pulse length
* Peak value, **Average Value
DIII-D
ITER
Max Baseline
1.7
6.2
3.0
15
2
5.3
16*
8.9**
27*
8.1**
1.7*
1.0**
0.5
3.7
4.5
2
13%
2.5%
6.0
1.8
500
300
ARIES-AT
5.2
13
6.0
18**
18**
2.2**
1.7
2.7
9.2%
5.4
1,755
S.S.
Fusion Energy Requirements:
 Confining the plasma so that alpha particles sustain fusion burn

Lawson Criteria: ntE ~ 1021 s/m3
 Heating the plasma for fusion reactions to occur

to 100 Million oC (routinely done in present experiments)
 Optimizing plasma confinement device to minimize the cost

Smaller devices

Cheaper systems, e.g., lower-field magnets (MFE) or lower-power
lasers (IFE)
 Extracting the fusion power and breeding tritium

Developing power extraction technology that can operate in
fusion environment

Co-existence of a hot plasma with material interface
First wall and blanket System is
subject to a harsh environment
Environment:
Outboard blanket & first wall
 Surface heat flux (due to X-ray and ions)
 First wall erosion by ions.
 Radiation damage by neutrons (e.g. structural
material)
 Volumetric heating by neutrons in the blanket.
 MHD effects
Functions:
 Tritium breeding management
 Maximize power recovery and coolant outlet
temperature for maximum thermal efficiency
Constraints:
 Simple manufacturing technique
 Safety (low afterheat and activity)
x ray
Neutrons
ions
New structural material should be
developed for fusion application




Fe-9Cr steels: builds upon 9Cr-1Mo industrial experience and materials database
(9-12 Cr ODS steels are a higher temperature future option)
SiC/SiC: High risk, high performance option (early in its development path)
W alloys: High performance option for PFCs (early in its development path)
Irradiation leads to a operating
temperature window for material
Structural Material Operating Temperature Windows: 10-50 dpa
Radiation
embrittlement
Carnot=1-Treject/Thigh
Thermal creep
Zinkle and Ghoniem, Fusion Engr.
Des. 49-50 (2000) 709
 Additional considerations such as He embrittlement and chemical
compatibility may impose further restrictions on operating window
Several blanket Concepts have been
developed
 Dual coolant with a self-cooled
PbLi zone, He-cooled RAFS
structure and SiC insert
 Simple, low pressure design with
SiC structure and LiPb coolant
and breeder.
 Innovative design leads to high
LiPb outlet temperature
(~1,100oC) while keeping SiC
structure temperature below
1,000oC leading to a high thermal
efficiency of ~ 60%.
 Flow configuration allows for a coolant outlet temperature to
be higher than maximum structure temperature
Design leads to a LiPb Outlet Temperature
of 1,100oC While Keeping SiC Temperature
Below 1,000oC
PbLi Inlet Temp. = 764 °C
•
Two-pass PbLi flow,
first pass to cool SiCf/SiC
box second pass to
superheat PbLi
Max. SiC/SiC
Temp. = 996°C
Max. SiC/PbLi Interf.
Temp. = 994 °C
First Wall
Channel
vback
Bottom
Pb-17Li
q''plasma
q''back
Inner
Channel
Poloidal
q'''LiPb
Top
Radial
SiC/SiC
First Wall
PbLi Outlet Temp. = 1100 °C
vFW
Out
SiC/SiC Inner Wall
Managing the plasma material
interface is challenging
 Alpha power and alpha ash has to
eventually leave the plasma

Confined
plasma
Flux
surface
Separatrix
First Wall
Particle and energy flux on the material
surrounding the plasma
 Modern tokomaks use divertors:





Closed flux surfaces containing hot core
plasma
Open flux surfaces containing cold
plasma diverted away from the first wall.
Particle flux on the first wall is reduced,
heat flux on the first wall is mainly due to
radiation (bremsstrahlung, synchrotron,
etc.)
Alpha ash is pumped out in the divertor
region
High heat and particle fluxes on the
divertor plates.
Edge Plasma
Divertor
plates
Several Gad-cooled W divertor
Concepts has been produced.
Mass flow rate [g/s]
EU finger: 2.6 cm diameter
Impinging multi-jet cooling
Allowable heat flux >10 MW/m2
~535,000 units for a power plant
Pp* / P *
Nup / Nu








Plate: 20 cm x 100 cm
Impinging slot-jet cooling
Allowable heat flux ~10 MW/m2
~750 units for a power plant
Nominal
operating
condition
Re (/104)
 Thermal hydraulic experiments confirm
very high heat transfer for slot jet cooling
 H > 50 kW/(m2K) is possible
The ARIES-AT utilizes an efficient
superconducting magnet design
 On-axis toroidal field:
6T
 Peak field at TF coil:
11.4 T
 TF Structure: Caps and straps
support loads without inter-coil
structure;
Superconducting Material
 Either LTC superconductor (Nb3Sn and
NbTi) or HTC
 Structural Plates with grooves for winding
only the conductor.
Radioactivity levels in fusion power plants
are very low and decay rapidly after shutdown
1
10
 SiC composites lead to a very low
activation and afterheat.
 All components of ARIES-AT qualify
for Class-C disposal under NRC and
Fetter Limits. 90% of components
qualify for Class-A waste.
0
10
Ferritic Steel
-1
th
Activity (Ci/W )
10
Vanadium
-2
10
-3
10
-4
10
ARIES-ST
ARIES-RS
-5
10
-6
10
1 mo
1d
100 y
1y
-7
10
4
10
5
10
6
10
7
10
8
10
9
10
10
10
11
10
Time Following Shutdown (s)
After 100 years, only 10,000 Curies
of radioactivity remain in the
585 tonne ARIES-RS fusion core.
Level in Coal Ash
Waste volume is not large
 1270 m3 of Waste is generated after 40 full-power year (FPY) of operation.
 Coolant is reused in other power plants
 29 m3 every 4 years (component replacement), 993 m3 at end of service
 Equivalent to ~ 30 m3 of waste per FPY
400
 90% of waste qualifies for
1400
Cumulative Compacted Waste Volume (m3)
Cumulative Compacted Waste Volume (m3)
 Effective annual waste can be reduced by increasing plant service life.
350
300
250
200
150
100
50
Class A disposal
1200
1000
800
600
400
200
0
Blanket
Shield
Vacuum
Vessel
Magnets Structure
Cryostat
0
Class A
Class C
Advances in fusion science & technology
has dramatically improved
our vision of fusion power plants
Major radius (m)
Estimated Cost of Electricity (c/kWh)
10
14
12
9
8
7
10
8
6
5
6
4
4
3
2
2
0
1
0
Mid 80's
Pulsar
Early 90's
ARIES-I
Late 90's
ARIES-RS
2000
ARIES-AT
Mid 80's
Physics
Early 90's
Physics
Late 90's
Physics
Advanced
Technology
In Summary, …
In a CO2 constrained world
uncertainty abounds
 No carbon-neutral commercial energy technology is available today.
Carbon sequestration is the determining factor for fossil fuel electric
generation.
 A large investment in energy R&D is needed.
 A shift to a hydrogen economy or carbon-neutral syn-fuels is also
needed to allow continued use of liquid fuels for transportation.
 Problem cannot be solved by legislation or subsidy. We need technical
solutions.


Technical Communities should be involved or considerable public
resources would be wasted
 The size of energy market ($1T annual sale, TW of power) is huge.
Solutions should fit this size market


100 Nuclear plants = 20% of electricity production
$50B annual R&D represents 5% of energy sale
Status of fusion power
 Over 15 MW of fusion power is generated (JET, 1997) establishing
“scientific feasibility” of fusion power

Although fusion power < input power.
 ITER will demonstrate “technical feasibility” of fusion power by
generating copious amount of fusion power (500MW for 300s) with
fusion power > 10 input power.
 Tremendous progress in understanding plasmas has helped
optimize plasma performance considerably. Vision of attractive
fusion power plants exists.
 Transformation of fusion into a power plant requires considerable
R&D in material and fusion nuclear technologies (largely ignored or
under-funded to date).

This step, however, can be done in parallel with ITER
 Large synergy between fusion nuclear technology R&D and Gen-IV.
Thank You