The Energy Challenge –Fusion Energy

Farrokh NajmabadiProf. of Electrical EngineeringDirector of Center for Energy ResearchUC San Diego

November 21, 2007

Fusion is one of very few non-carbon based energy options

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)

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)

D + 6Li 2 4He + 3.5 MeV (Plasma) + 17 MeV (Blanket)

D + T 4He (3.5 MeV) + n (14 MeV)

n + 6Li 4He (2 MeV) + T (2.7 MeV)nT

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 with large gain (fusion power/input power).

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 with large gain (fusion power/input power).

Two Approaches to Fusion Power –2) Magnetic Fusion

Rest of the Talk is focused on MFE Rest of the Talk is focused on MFE

Magnetic Fusion Energy (MFE) Strong magnetic pressure (100’s atm) to confine a low density but

high pressure (10’s atm) plasma. Particles confined within a “toroidal magnetic bottle” for 10’s km

and 100’s of collisions per fusion event. At sufficient plasma pressure and “confinement time”, the 4He

power deposited in the plasma sustains fusion condition.

Magnetic Fusion Energy (MFE) Strong magnetic pressure (100’s atm) to confine a low density but

high pressure (10’s atm) plasma. Particles confined within a “toroidal magnetic bottle” for 10’s km

and 100’s of collisions per fusion event. At sufficient plasma pressure and “confinement time”, the 4He

power deposited in the plasma sustains fusion condition.

Plasma behavior is dominated by “collective” effects

Pressure balance (equilibrium) does not guaranty stability. Example: Interchange stability

Pressure balance (equilibrium) does not guaranty stability. Example: Interchange stability

Impossible to design a “toroidal magnetic bottle” with good curvatures everywhere.

Fortunately, because of high speed of particles, an “averaged” good curvature is sufficient.

Impossible to design a “toroidal magnetic bottle” with good curvatures everywhere.

Fortunately, because of high speed of particles, an “averaged” good curvature is sufficient.

Outside part of torus inside part of torusFluid Interchange Instability

Tokamak is the most successful concept for plasma confinement

R=1.7 m

DIII-D, General AtomicsLargest US tokamak

Many other configurations possible depending on the value and profile of “q” and how it is generated (internally or externally)

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

R=1 m

0.06 MAPlasma Current

JET is currently the largest tokamak in the world

R=3 m

4 MAPlasma Current

Fusion Energy Requirements:

Heating the plasma for fusion reactions to occur to 100 Million Celsius (routinely done in present experiments)

Confining the plasma so that alpha particles sustain fusion burn Energy Replacement time of about 1 s Plasma density of 1021 /m3 (Air Density is 3X1025 /m3 ) Progress in confinement is measured by “Fusion Triple

Product” = (plasma temperature)X(energy replacement time)X(plasma density)

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

Heating the plasma for fusion reactions to occur to 100 Million Celsius (routinely done in present experiments)

Confining the plasma so that alpha particles sustain fusion burn Energy Replacement time of about 1 s Plasma density of 1021 /m3 (Air Density is 3X1025 /m3 ) Progress in confinement is measured by “Fusion Triple

Product” = (plasma temperature)X(energy replacement time)X(plasma density)

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

Progress in plasma confinement has been impressive

500 MW of fusion Power for 300s

Construction will be started shortly in France

500 MW of fusion Power for 300s

Construction will be started shortly in France

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uct

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102

1 m

-3) (

s) T

(keV

)

ITER Burning plasma experiment

Large amount of fusion power has also been produced

ITER Burning plasma experiment

DT Experiments

DD Experiments

We have made tremendous progress in understanding 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.

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.

Fusion: Looking into the future

ITER will demonstrate the technical feasibility of fusion energy

Power-plant scale device. Baseline design: 500 MW of fusion power for 300s Does not include breeding

blanket or power recovery systems.

ITER agreement was signed in Nov. 2006 by 7 international partners (US, EU, Japan, Russa, China, Korea, and India)

Construction will begin in 2008.

Power-plant scale device. Baseline design: 500 MW of fusion power for 300s Does not include breeding

blanket or power recovery systems.

ITER agreement was signed in Nov. 2006 by 7 international partners (US, EU, Japan, Russa, China, Korea, and India)

Construction will begin in 2008.

ARIES-AT is an attractive vision for fusion with a reasonable extrapolation in physics & technology

Competitive cost of electricity (5c/kWh);

Steady-state operation;

Low level waste;Public & worker

safety;High availability.

Competitive cost of electricity (5c/kWh);

Steady-state operation;

Low level waste;Public & worker

safety;High availability.

ITER and satellite tokamaks will provide the necessary data for a fusion power plant

DIII-D DIII-D ITER

Simultaneous Max Baseline ARIES-AT

Major toroidal radius (m) 1.7 1.7 6.2 5.2

Plasma Current (MA) 2.25 3.0 15 13

Magnetic field (T) 2 2 5.3 6.0

Electron temperature (keV) 7.5* 16* 8.9** 18**

Ion Temperature (keV) 18* 27* 8.1** 18**

Density (1020 m-3) 1.0* 1.7* 1.0** 2.2**

Confinement time (s) 0.4 0.5 3.7 1.7

Normalized confinement, H89 4.5 4.5 2 2.7

(plasma/magnetic pressure) 6.7%13% 2.5% 9.2%

Normalized 3.9 6.0 1.8 5.4

Fusion Power (MW) 500 1,755

Pulse length 300 S.S.

DIII-D DIII-D ITER

Simultaneous Max Baseline ARIES-AT

Major toroidal radius (m) 1.7 1.7 6.2 5.2

Plasma Current (MA) 2.25 3.0 15 13

Magnetic field (T) 2 2 5.3 6.0

Electron temperature (keV) 7.5* 16* 8.9** 18**

Ion Temperature (keV) 18* 27* 8.1** 18**

Density (1020 m-3) 1.0* 1.7* 1.0** 2.2**

Confinement time (s) 0.4 0.5 3.7 1.7

Normalized confinement, H89 4.5 4.5 2 2.7

(plasma/magnetic pressure) 6.7%13% 2.5% 9.2%

Normalized 3.9 6.0 1.8 5.4

Fusion Power (MW) 500 1,755

Pulse length 300 S.S.

* Peak value, **Average Value

The ARIES-AT utilizes an efficient superconducting magnet design

On-axis toroidal field: 6 T

Peak field at TF coil: 11.4 T

TF Structure: Caps and straps support loads without inter-coil structure;

On-axis toroidal field: 6 T

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.

Superconducting Material Either LTC superconductor (Nb3Sn and

NbTi) or HTC Structural Plates with grooves for winding

only the conductor.

Use of High-Temperature Superconductors Simplifies the Magnet Systems

HTS does offer operational advantages: Higher temperature operation

(even 77K), or dry magnets Wide tapes deposited directly

on the structure (less chance of energy dissipating events)

Reduced magnet protection concerns

HTS does offer operational advantages: Higher temperature operation

(even 77K), or dry magnets Wide tapes deposited directly

on the structure (less chance of energy dissipating events)

Reduced magnet protection concerns

Inconel strip

YBCO Superconductor Strip Packs (20 layers each)

8.5 430 mm

CeO2 + YSZ insulating coating(on slot & between YBCO layers)

Epitaxial YBCOEpitaxial YBCO

Inexpensive manufacture would consist on layering HTS on structural shells with minimal winding!

Epitaxial YBCOEpitaxial YBCO

Inexpensive manufacture would consist on layering HTS on structural shells with minimal winding!

DT Fusion requires a T breeding blanket

Requirement: Plasma should be surrounded by a blanket containing Li

D + T He + n

n + 6Li T + He Through careful design, only a small fraction of neutrons are absorbed

in structure and induce radioactivity Rad-waste depends on the choice of material: Low-activation material Rad-waste generated in DT fusion is similar to advanced fuels (D-3He) For liquid coolant/breeders (e.g., Li, LiPb), most of fusion energy (carried

by neutrons) is directly deposited in the coolant simplifying energy recovery

Issue: Large flux of neutrons through the first wall and blanket: Need to develop radiation-resistant, low-activation material: Ferritic steels, Vanadium alloys, SiC composites

Requirement: Plasma should be surrounded by a blanket containing Li

D + T He + n

n + 6Li T + He Through careful design, only a small fraction of neutrons are absorbed

in structure and induce radioactivity Rad-waste depends on the choice of material: Low-activation material Rad-waste generated in DT fusion is similar to advanced fuels (D-3He) For liquid coolant/breeders (e.g., Li, LiPb), most of fusion energy (carried

by neutrons) is directly deposited in the coolant simplifying energy recovery

Issue: Large flux of neutrons through the first wall and blanket: Need to develop radiation-resistant, low-activation material: Ferritic steels, Vanadium alloys, SiC composites

Outboard blanket & first wall

ARIES-AT features a high-performance blanket

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%.

Simple manufacturing technique.

Very low afterheat.

Class C waste by a wide margin.

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%.

Simple manufacturing technique.

Very low afterheat.

Class C waste by a wide margin.

Modular sector maintenance enables high availability

Full sectors removed horizontally on rails Transport through maintenance corridors to hot

cells Estimated maintenance time < 4 weeks

Full sectors removed horizontally on rails Transport through maintenance corridors to hot

cells Estimated maintenance time < 4 weeks

ARIES-AT elevation view

Advances in fusion science & technology has dramatically improved our vision of fusion power plants

Estimated Cost of Electricity (c/kWh)

0

2

4

6

8

10

12

14

Mid 80'sPhysics

Early 90'sPhysics

Late 90's Physics

AdvancedTechnology

Major radius (m)

0

1

2

3

4

5

6

7

8

9

10

Mid 80's Pulsar

Early 90'sARIES-I

Late 90'sARIES-RS

2000 ARIES-AT

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

101

104 105 106 107 108 109 1010 1011

ARIES-STARIES-RS

Act

ivit

y (

Ci/

W th)

Time Following Shutdown (s)

1 mo 1 y 100 y1 d

After 100 years, only 10,000 Curies

of radioactivity remain in the

585 tonne ARIES-RS fusion core.

After 100 years, only 10,000 Curies

of radioactivity remain in the

585 tonne ARIES-RS fusion core.

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.

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.

Ferritic SteelVanadium

Radioactivity levels in fusion power plantsare very low and decay rapidly after shutdown

Level in Coal AshLevel in Coal Ash

Fusion Core Is Segmented to Minimize the Rad-Waste

Only “blanket-1” and divertors are replaced every 5 years

Only “blanket-1” and divertors are replaced every 5 years

Blanket 1 (replaceable)

Blanket 2 (lifetime)

Shield (lifetime)

Waste volume is not large

0

50

100

150

200

250

300

350

400

Blanket Shield VacuumVessel

Magnets Structure Cryostat

Cu

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lati

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Co

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Wa

ste

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m3

)

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 Effective annual waste can be reduced by increasing plant service life.

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 Effective annual waste can be reduced by increasing plant service life.

90% of waste qualifies for Class A disposal

90% of waste qualifies for Class A disposal

Fusion: Why is taking so long?

There has been no urgency in developing new sources of energy

Proposed fusion development plan in 1976 aimed at fielding a fusion Demo by 2000.

Recent DOE Fusion Development Plan (2003) aimed at fielding a fusion Demo by 2030.

The required funding to implement the plans were not approved. Proposals for fielding a burning plasma experiments since mid

1980s. Fusion program was restructured in mid 1990s, focusing on

developing fusion sciences (with 1/3 reduction in US funding). Fielding a fusion Demo is NOT the official goal of DOE at present

Large interest and R&D investment in Europe and Japan (and China, India, Korea)

Proposed fusion development plan in 1976 aimed at fielding a fusion Demo by 2000.

Recent DOE Fusion Development Plan (2003) aimed at fielding a fusion Demo by 2030.

The required funding to implement the plans were not approved. Proposals for fielding a burning plasma experiments since mid

1980s. Fusion program was restructured in mid 1990s, focusing on

developing fusion sciences (with 1/3 reduction in US funding). Fielding a fusion Demo is NOT the official goal of DOE at present

Large interest and R&D investment in Europe and Japan (and China, India, Korea)

Development of fusion has been constrained by funding!

Cumulative Funding

0

5000

10000

15000

20000

25000

30000

35000

1985

1990

1995

2000

2005

2010

2015

2020

2025

2030

2035

ITERITER

DemoDemo

Magnetic Fusion Engineering Act

of 1980

Actual

Fusion Energy DevelopmentPlan, 2003 (MFE)

$M

, FY

02

19

80

FEDITER

Demo Demo

Current cumulative funding

~ 1 week of world energy sale

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 US electricity production $50B annual R&D represents 5% of energy sale

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 US 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

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

Thank you!Any Questions?