March 2, 2006

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Fusion as a Future Energy Source

• March 2, 2006
• Yong-Seok Hwang
• Dept. of Nuclear Engineering
• Seoul National University
• yhwang_at_snu.ac.kr
• http//nuplex.snu.ac.kr

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Outline

• Introduction to Fusion
• The Power of the Universe
• What is Fusion?
• How Does Fusion Work?
• What is the Fusion Challenge?
• Korean Fusion Program KSTAR
• International Fusion Program ITER
• Roadmap to Fusion Reactor
• Nuclear Technologies for Fusion Reactor

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Fusion The Power of the Universe
Fusion is perhaps the only option for a
truly sustainable or long term energy source, The
fuel is virtually inexhaustible and readily
available throughout the world. Power plant
operation will be inherently safe without the
risk of long-lived radioactive waste. Fusion will
be environmentally sound without atmospheric
pollutants or contribution to global warming. It
will be economically attractive and capable of
producing the energy that future generations will
require. The sun and stars are powered by fusion.
Harnessing these reactions to produce energy on
earth presents a grand challenge to scientists
and engineers. Steady progress has been made but
several scientific and technological advances are
necessary before the dream of commercial
electricity production will become a reality
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Why should we develop Fusion?
By the middle of the next century, the
world's population will double and energy demand
will triple. This is due in large part, to the
industrialization and economic growth of
developing nations. Continued use of fossil fuels
(coal, oil and natural gas) will rapidly deplete
these limited and localized natural resources.
There is, perhaps, another 50-100 years supply of
oil and natural gas and enough coal for several
hundred years. Burning these fossil fuels
threatens to irreparably harm our environment. On
the other hand, the deuterium in the earth's
oceans is sufficient to fuel advanced fusion
reactors for millions of years. The waste product
from a deuterium-tritium fusion reactor is
ordinary helium.
Solar and renewable energy technologies will play
a role in our energy future. Although they are
inherently safe and feature an unlimited fuel
supply, they are geographically limited, climate
dependent and unable to meet the energy demands
of a populous and industrialized world. Another
option, nuclear fission, suffers from a negative
public perception. High-level radioactive waste
disposal challenges and the proliferation threat
of weapons-grade nuclear materials are principle
concerns. The fuel supply in this case is large
but ultimately limited (100-200 years without
breeder reactors).
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What is Fusion?
Fusion is combining the nuclei of light
elements to form a heavier element. This is a
nuclear reaction and results in the release of
large amounts of energy! In a fusion reaction,
the total mass of the resultant nuclei is
slightly less than the total mass of the original
particles. An example can be seen in the
Deuterium-Tritium Fusion Reaction.
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Various Fusion Reactions
3.5MeV 14.1MeV 17.6MeV
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Coulomb Barrier
Potential Energy vs. Nuclear Separation
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Fusion Reaction Cross Sections
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How does Fusion work?

• In order for fusion reactions to occur, the
  particles must be hot enough (temperature), in
  sufficient number (density) and well contained
  (confinement time). These simultaneous conditions
  are represented by a fourth state of matter known
  as plasma. In a plasma, electrons are stripped
  from their nuclei. A plasma, therefore, consists
  of charged particles, ions and electrons.
• There are three principle mechanisms for
  confining these hot plasmas - magnetic, inertial
  and gravity.

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Magnetic Confinement Concept
Good Perpendicular Confinement, but Strong End
Loss
Magnetic Mirror
Tokamak
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World-Class Fusion Devices
TFTR
JET
JT60-U T-15 DIII-D C-MOD ToreSupra ASDEX-U NSTX MA
ST
LHD
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Where Are We?
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JET News - December 1997JET IMPROVES ITS WORLD
RECORD PERFORMANCE
The NEWS that two new world records had been
set by JET came just hours after the Director,
Dr Martin Keilhacker had addressed
representatives of the worlds media at a press
conference held at the Royal Society, London, on
31 Octorber. That days experiment had
resulted in new figures of 16 MW of peak fusion
power, an improvement of 3MW, and a new ratio of
power out to power in of 65, 5 up on the
previous record.
On 5 November, JET achieved 21 Mega-joules of
fusion energy, increasing its own best
performance by a further 7 MJ. This was
announced on the same day at the Fusion
Exhibition in Brussels by Professor Troyon,
Chairman of the JET Council.
WHAT JET HAS ACHIEVED THIS YEAR
JET has set three new world records 21 MJ
of fusion energy 16 MW of peak fusion power
and a ration of fusion power produded to net
input power of 65
JET has demonstrated that, using
deuterium-tritium fuel, there is a 25 reduction
in the power needed to maintain high confinement
in operation
JET has tested the first large scale plant of
the type needed to supply and process tritium in
a future fusion power station
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What is the Fusion Challenge?

• The ultimate objective of fusion energy research
  is the demonstration of a steady-state, high-gain
  (or "ignited" ) fusion plasma producing
  reactor-level fusion power. To accomplish this
  goal, we must improve our understanding of the
  underlying physics principles and advance the
  state-of-the-art of critical enabling
  technologies.
• Improving physics understanding The transport
  of heat particles from the plasma, the
  contribution of magneto hydrodynamic modes and
  instabilities and the effects of large
  populations of energetic alpha particles are
  examples of areas that require improved physics
  understanding so that techniques can be developed
  to improve the performance and reduce the size
  and cost of future fusion reactors.
• Developing enabling technologies High strength
  materials that do not become excessively
  activated from fusion neutrons or weakened due to
  the nuclear after-heat are needed for the reactor
  structure. First-wall materials with adequate
  thermal conductivity to carry away the heat flux
  from the high temperature fusion plasma are
  required. Large bore, high field superconducting
  magnets are necessary to provide the required
  steady-state confinement of fusion plasmas.

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World-Wide Tokamak Performance and KSTAR Target
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Fusion Research Activities and Plans in Korea

• Basic Plasma and Fusion Research at University
  1970s
• Construction of Small-scale Fusion Research
  Device 1980-1990s
• SNUT- 79 Tokamak (SNU)
• KT- 1 Tokamak (KAERI)
• KAIST Tokamak (KAIST)
• HANBIT Mirror Device (KBSI)
• Korean National Fusion Program 1995 ?
• KSTAR Tokamak Project Universities, Research
  Institutes and Major Industries with Emphasis on
  International Collaboration
• Collaboration with Major International Fusion
  Program 2004 ?
• Operate KSTAR as International Fusion
  Collaboratory
• Participate Major International Fusion Program,
  ITER
• Proto Fusion Reactor Construction (1.5 GWe
  Class) 2030s

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KSTAR Tokamak ProjectKSTAR Korea
Superconducting Tokamak Advanced Research

• Mission
• The mission of the KSTAR project is to develop a
  steady-state-capable advanced superconducting
  tokamak to establish the scientific and
  technological base for an attractive fusion
  reactor as a future energy source.
• KSTAR Tokamak Research Objectives
• To extend present stability and performance
  boundaries of tokamak operation through active
  control of profiles and transport.
• To explore methods to achieve steady-state
  operation for tokamak fusion reactors using
  non-inductive current drive.
• To integrate optimized plasma performance and
  continuous operation as a step toward an
  attractive tokamak fusion reactor.

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KSTAR Design Features

• Medium Size
• Major Radius (R) 1.8 m, Minor (a) 0.5 m
• Magnetic Field at Plasma Center (B) 3.5 Tesla
• Plasma Current (I) 2000 kA
• Elongation 2.0
• Triangularity 0.8
• Fully Superconducting Magnet
• Long Pulse Operation Capability (20 sec
• Toroidal Field Coil (TF Coil) Nb3Sn
• Poloidal Field Coil (PF Coil) Nb3Sn(PF1-5),
  NbTi(PF6-7)

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KSTAR Tokamak
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KSTAR Facility Construction
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World-Wide Fusion Devices under Construction
W7-X
NIF
SSAT,
EAST
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ITER Design
Blanket Module
Central Solenoid
Vacuum Vessel
Outer Intercoil Structure
Cryostat
Toroidal Field Coil
Port Plug
Poloidal Field Coil
Divertor
Machine Gravity Supports
Torus Cryopump
ITER International Thermonuclear Experimental
Reactor, The Way in Latin
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ITER Parameters
Total fusion power 500 MW (700MW) Q fusion
power/auxiliary heating power 10 Average neutron
wall loading 0.57 MW/m2 (0.8
MW/m2) Plasma inductive burn time 300 s
Plasma major radius 6.2 m Plasma minor
radius 2.0 m Plasma current (Ip) 15 MA
(17.4 MA) Vertical elongation _at_95 flux
surface/separatrix 1.70/1.85 Triangularity _at_95
flux surface/separatrix 0.33/0.49 Safety factor
_at_95 flux surface 3.0 Toroidal field _at_ 6.2 m
radius 5.3 T Plasma volume 837 m3 Plasma
surface 678 m2 Installed auxiliary
heating/current drive power 73 MW (100 MW)
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ITER Engineering Design I

• The superconducting magnet system has three main
  subsystems
• 18 toroidal field (TF) coils
• 6 poloidal field (PF) coils
• a central solenoid (CS) coil
• Magnet system weighs about 8,700 ton
• Maximum inner dimensions
• 28 m diameter, 24 m height

• Operation equivalent to a few 10,000 inductive
  pulses of 300500 sec.
• Average neutron flux 0.5 MW/m2
• Average fluence 0.3 MWa/m2

Heat Transfer Systems (Water-cooled) 750 MW at 3
and 4.2 MPa water pressure,120C
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ITER Engineering Design II
Double-wall Vacuum Vessel
SC Magnets (TF, PF, CS)
First Wall/Blanket Be armor, Cu-alloy heat sink
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Cost Categories

• Those that can only sensibly be purchased by the
  host country.
• Those which are of minor technical interest or
  size, and whose cost burden must therefore be
  shared by all Parties. For these items a
  centrally administered fund can be established.
• Items of interest to all the Parties due
  primarily to their high technology content. To
  ensure each Party obtains its fair share of these
  items, the Parties must agree beforehand which
  ones each will contribute. To do this, all
  Parties must agree on their value to the project.
  This requires an agreed valuation of items, as
  described below. Each Party will contribute its
  agreed items "in kind", using the purchasing
  procedures and funding arrangements it prefers.
  Thus the actual costs to each Party may not
  correspond to the project valuation - it may
  differ due to competitive tendering as well as
  different unit costs.

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ITER Parties Site Selection
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Roadmap to Fusion Energy (US)
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Roadmap to Fusion Energy (EU)
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Fusion and Material Development Path
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International Fusion Material Test Facility
(IFMTF)
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Fast Track to Fusion Energy
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Nuclear Technologies for Fusion Reactor
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ITER Blanket Development
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Blanket Options
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He Cooled Pebble Bed (EU, Japan, US)
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ARIES Blanket (LiPb Coolant, SiC Structure)
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Our Future with Fusion Energy ?