The Path to Fusion Power Chris Llewellyn Smith Director UKAEA Culham Chairman Consultative Committee

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The Path to Fusion Power Chris Llewellyn
SmithDirector UKAEA CulhamChairman
Consultative Committee for Euratom on Fusion
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FUSION

• powers the sun and stars
• and a controlled magnetic confinement fusion
  experiment at the Joint European Torus (JET)
• (in the UK) has produced 16 MW of fusion power
• so it works

The big question is - when will it work reliably
and economically, on the scale of a power
station? First What is it? Why bother? Why is it
taking so long?
s
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WHAT IS FUSION ?

• Most effective fusion process involves deuterium
  (heavy hydrogen) and tritium (super heavy
  hydrogen) heated to above 100 million C

• A magnetic bottle called a tokamak keeps the
  hot gas away from the wall
• Challenges make an effective magnetic bottle
  (now done ?)
• a robust container, and a reliable system
• ten million times more than in chemical
  reactions, e.g. in burning fossil fuels ??while a
  1 GW coal power station would use 10,000 tonnes
  of coal a day, a fusion power station would only
  use 1 Kg of D T

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WHAT IS FUSION ?

• Most effective fusion process involves deuterium
  (heavy hydrogen) and tritium (super heavy
  hydrogen) heated to above 100 million C

• A magnetic bottle called a tokamak keeps the
  hot gas away from the wall
• Challenges make an effective magnetic bottle
  (now done ?)
• a robust container, and a reliable system
• ten million times more than in chemical
  reactions, e.g. in burning fossil fuels ??while a
  1 GW coal power station would use 10,000 tonnes
  of coal a day, a fusion power station would only
  use 1 Kg of D T

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Why bother?

• Lithium in one laptop battery (? tritium from the
  reaction neutron (from fusion) lithium ?
  tritium helium)
• 40 litres of water (from which heavy
  water/deuterium can easily be extracted), used
  to fuel a fusion power station, would provide
  200,000 kW-hours
• (US electricity production)/(population) for 15
  years
• in an intrinsically safe manner with no CO2
• Unless/until we find a barrier, this is
  sufficient reason to develop fusion power

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A Fusion Power plant would be like a conventional
one, but with a different fuel and furnace
The blanket captures energetic neutrons produced
in the fusion process
The neutrons react with lithium in the blanket to
produce Tritium (? fuel the reactor)
The neutrons energy ? heat which is extracted
through a cooling circuit and used to boil water
and produce steam to drive a generator
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FUSION ADVANTAGES

• unlimited fuel
• no CO2 or air pollution
• intrinsic safety
• no radioactive ash and no long-lived
  radioactive waste
• competitive electricity generation cost, if
  reasonable availability (e.g 75) can be achieved
• compared to most other carbon free electricity
  sources

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FUSION DISADVANTAGES

• The blankets will become radioactive
• but can choose materials so that half lives 10
  years, and all components could be recycled ? new
  fusion power plant within 100 years (no waste
  for permanent repository disposal no long-term
  burden on future generations)
• More research and development needed
• Fusion power stations will need plasma volumes
  of at least 1000 m3 (ten times JET), so small
  scale demonstration impossible (hence -
  relatively slow - step by step progress)

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Progress in Fusion has been enormous, but even
JET (currently the worlds leading fusion
research facility) is not large enough to be a
(net) source of power
T3 Volume 1 m3 Temperature 3 M 0C Established
tokamak as best configuration (1969)

• JET Volume 100 m3
• Temperature 150 M 0C
• World record (16 MW) for fusion power (1997)

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JET
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Progress

• Huge strides in physics, engineering, technology
• JET 16 MW of fusion power equal to heating
  power.
• Ready to build a Giga Watt-scale tokamak ITER
  expected to produce 10 x power needed to heat the
  plasma
• Pi pressure in plasma
• tE (energy in plasma)/(power supplied to keep
  it hot)

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JET provides key contributions to predict ITER
performance
JET
Cross section of present EU D-shape tokamaks
compared to the ITER project

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NEXT STEPS FOR FUSION

• Construct ITER (International Tokamak
  Experimental Reactor)
• energy out 10? energy in
• burning plasma
• During construction, further improve tokamak
  performance in experiments at JET, DIII-D,
  ASDEX-U, JT- 60further develop technology, and
  continue work on alternative configurations
  Spherical Tokamaks (pioneered in UK),
  Stellarators
• Intensified RD on materials for plasma facing
  and structural components and test of materials
  at the proposed International Fusion Materials
  Irradiation Facility (IFMIF)

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ITER
JET (to scale)
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ITER

• Aim - demonstrate integrated physics and
  engineering on the scale of a power station
• Key ITER technologies fabricated and tested by
  industry
• 4.5 Billion Euro construction cost (will be at
  Cadarache in southern France)
• Partners house over half the worlds population

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Plasma Physics Issues

• Major positive developments (1980s and 90s)
• Bootstrap plasma current (predicted at Culham)
  ? much less external power needed than
  previously thought
• High confinement mode (serendipitous discovery
  at Garching) ? higher pressure more fusion
  power with given magnetic field
• Potential Problems
• New instabilities in burning plasmas?
• Steady state operation in power station
  conditions (looks possible with help of bootstrap
  current if not, could ? pulsed machine, or
  stellarator)
• Potential improvement
• Better control of potential instabilites to
  allow higher pressure

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Spherical Tokamaks

• Based on promising, more compact but less
  developed, configuration than JET and ITER - use
  magnetic field much more efficiently (but face
  other challenges)
• START (Culham, UK 1991-1998, first substantial
  Spherical Tokamak) raised
  world record for key figure of merit ? ( ratio
  of plasma to magnetic pressure) from 13 to 40 !
  
• Many STs built subsequently worlds leading STs
  are
• NSTX (Princeton) and MAST (Culham)

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Spherical Tokamaks

• Making important contributions to conventional
  tokamak physics
• different shape ? new perspective
• Could play vital role as a Component Test
  Facility in the medium-term
• A CTF, which would test whole components
  (blankets, welds, joints,), is a highly
  desirable (perhaps essential) step between ITER
  and a prototype power station
• Could, in long-run, be basis for (smaller and
  simpler) power stations
• No superconducting magnets ? cheaper and simpler

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STELLARATORS(Originally pioneered at Princeton)

• Helical field, needed to confine plasma, provided
  externally
• Avoid need to drive the Mega Amp currents that
  provide (part of the) helical fields in Tokamaks,
  and are a source of instabilities
• Intrinsically steady state devices. The price is
  greater complexity.
• LHD in Japan W7-X under construction in
  Germany

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MATERIALS

• Structural materials subjected to bombardment
  of 2 MW/m2 from 14 MeV neutrons
• Plasma facing materials subjected to an
  additional 500 kW/m2 from hot particles and
  electromagnetic radiation (much more on
  divertor)
• Various materials have been considered, and
  there are good candidates that may survive in
  these conditions, BUT
• Further modelling experiments essential
• Only a dedicated (800M) accelerator-based test
  facility - the International Fusion Materials
  Irradiation Facility (IFMIF) - can reproduce
  reactor conditions results from IFMIF will be
  needed before a prototype commercial reactor can
  be licensed and built

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Materials Issues

• Major positive development (1990s)
• Body-centred cubic low activation steels seem
  able to withstand neutron damage
• Potential problems
• Effect of helium generation in the materials
• Heat on divertor (can be reduced by
  compromising design)
• Potential improvement
• Development of advanced materials (SiC
  ceramics,) for much higher temperature operation

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Swelling resistant alloys have been developed via
international collaborations
Lowest swelling is observed in body-centered
cubic alloys (V alloys, ferritic steel)
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European Power Plant Conceptual Study

• Results
• Confirm good safety and environmental features
  of fusion
• Give encouraging range for the expected cost of
  fusion generated electricity (9 -cents/kW-hour
  for early near-term water cooled steel model 5
  -cents/kW-hour for early advanced Li-Pb cooled
  Si-C composites model)
• Note
• Economics favours large fusion power plants ?
  major centres of population (complementary to
  renewables)
• Capital intensive very low operating cost
  lots of cheap off peak power ? hydrogen?
• Results of this study used as input to Culham
  Fast Track study

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ONE BLANKET DESIGN FROM EUROPEAN CONCEPTUAL POWER
PLANT STUDY
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FUSION FAST TRACK

• During ITER construction
• operate JET, DIII-D, JT60 ? speed up/improve
  ITER operation
• In parallel intensify materials work, approve
  and build IFMIF
• Then, having assimilated results from ITER and
  IFMIF, build a Prototype Power Plant (DEMO)
• ? Fusion a reality in our lifetimes

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Fast Track - Pillars Only
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Conclusions on Fusion

• DEMO could be putting fusion power into the grid
  in under 30 years, given
• Funding to begin IFMIF in parallel with ITER,
  plus technology development and start of design
  of DEMO
• No major adverse surprises
• world fusion funding 1.5 billion pa c/f
  electricity (energy) market 1.5 trillion (4.5
  trillion) p.a.
• The cocktail of energy sources that are needed
  (plus improved efficiency) to meet the energy
  challenge must include large-scale sources of
  base load electricity fusion is one of very few
  options