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Developing Materials for Fusion Power

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International Fusion Materials Irradiation Facility (IFMIF) ... Lack of understanding of effects of neutron irradiation on the structure ... – PowerPoint PPT presentation

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Title: Developing Materials for Fusion Power


1
Developing Materials for Fusion Power
  • May 10, 2007
  • Shreya Dave
  • Christopher Whitfield
  • 22.012 Fusion and Plasma Physics
  • Professor Molvig

2
Outline
  • Why Materials?
  • What are their applications?
  • What conditions must they have the ability to
    withstand?
  • What current research exists?
  • Pros/cons of each
  • Future outlook of each project
  • What is the development strategy?
  • How do we test these materials?
  • International Fusion Materials Irradiation
    Facility (IFMIF)
  • What are the concerns for unsafe materials?

3
Why all this Materials Talk?
  • The development of materials for use in nuclear
    fusion is perhaps the most critical component of
    the further development of fusion technology.
  • Also, however, one of the biggest barriers.
  • The research and development of these materials
    has been based on international collaboration
    from the beginning, like much of fusion
    development, so its a good slice of fusion
    development to look at
  • Personal motivations.

4
Areas of Application
  • Plasma facing components absorb the thermal
    radiation and maintain the vacuum
  • First wall
  • Diverters
  • Limiters
  • Breeding Blanket where neutrons are absorbed to
    breed tritium.

5
ConditionsDetails
  • The Materials must, in general, withstand extreme
    energies, such as
  • 14 MeV neutrons
  • Neutral and Charged Plasma Particles
  • High surface heat fluxes
  • These materials must also possess
  • Sufficient lifetime of plasma facing components
    or breeding blanket
  • The ability to withstand expected surface heat
    and neutron wall load
  • Ability to withstand the inherent displacement
    rate and transmutations reaction rates

6
ConditionsEhrlich Said It
In the long term development, materials which
can withstand high neutron wall loads under
temperature and coolant pressure conditions
necessary to drive efficient thermodynamic
working cycles must be developed (Ehrlich 80).
7
Material Possibilities
  • Ferritic-martensitic steels
  • Vanadium Alloys
  • SiC/SiC ceramics
  • Tungsten Alloys

8
Ferritic Martensitic Steels Ehrlich Said It
  • Furthest along the development path in that
    there exists a well developed technology and a
    broad industrial experience with such alloys in
    fossil and nuclear energy technology (Ehrlich
    82).

9
Ferritic Martensitic Steels Positives
  • Thermophysical and mechanical properties
  • Compatibility with major cooling and breeding
    materials
  • Low sensitivity to swelling and helium
    embrittlement

10
Ferritic Martensitic Steels Drawbacks and
Clarifications
  • Observed radiation-induced degradation of flow
    and fracture properties below about 350 Celsius
  • Influence of ferromagnetism on plasma stability
    and Lorenz forces

11
Ferritic Martensitic Steels Future Work
  • Use of nano-scaled oxide dispersions and
    precipitates to expand application to higher T
  • Need to develop a broad database to qualify
    material for use in breeding blankets
  • Need to look at both structural and functional
    qualities of the material

12
Vanadium Alloys Ehrlich Said It
Have a favorable combination of physical
properties and high creep strength and hence the
greatest potential of the three material groups
for high temperature operation in liquid lithium
(Ehrlich 82).
13
Vanadium Alloys Positives
  • Fastest decay of radioactivity in addition to
    long decay times
  • Positive swelling and high temperature
    embrittlement results.

14
Vanadium Alloys Drawbacks
  • High solubility and permeability of tritium and
    solubility of interstitial elements (like O, C,
    N).

15
Vanadium Alloys Future Work
  • Development of self-heating, insulating, AND
    corrosion-protective material.
  • This is the approach to help overcome
    magnetohydrodynamic effects in the breeding
    blanket

16
SiC/SiC Ceramics Ehrlich Said It
  • Potentially the most difficult challenge of
    the three groups of materials. They have
    potentially high payoffs in terms of very low
    radioactivity and decay heat at short and
    intermediate decay times and offer high operating
    temperatures (Ehrlich 82).

17
SiC/SiC Ceramics Positives
  • Low radioactivity
  • Decay heat quickly
  • High operating temperatures

18
SiC/SiC Ceramics Drawbacks
  • Lack of understanding of effects of neutron
    irradiation on the structure
  • Limited production technology
  • Insufficient heremtic sealing capabilities

19
SiC/SiC Ceramics Future Work
  • Must develop radiation-resistant materials
  • Also, develop appropriate design rules for use of
    materials in structural parts.

20
Development Process
  • Phase I Initial experimentation
  • Effectively everything that has taken place thus
    far
  • Phase II Concept Exploration Phase
  • Data base development, some tests
  • Phase III Concept Confirmation
  • More tests, ITER applications

21
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22
Development CommentsEhrlich Said It
  • Phase II Questions on compatibility,
    corrosion, mechanical interaction,
    radiation-induced swelling, creep and dimensional
    instabilities in steep thermal and neutron
    gradients and the effective tritium release
    mechanisms have to be resolved (Ehrlich 83).
  • Wow.
  • Phase III A final concept confirmation of the
    selected design needs, however, the testing under
    real fusion neutron irradiation in a follow-on
    development phase III. This very late
    confirmation of a concept reveals the weak point
    in the presently adapted RD strategy (Ehrlich
    83).
  • This is not ideal!

23
Whats Next?We really cant figure out we did
this wrong 20 years from now.
  • We must figure out a way to test these materials
    that does not require a fully developed fusion
    reactor.
  • Otherwise, we might find that twenty years from
    now, much of our work was in vain.

24
Materials TestingOutline
  • The materials of a fusion reactor, especially
    those in the first wall and breeder components,
    are exposed to harsh environments.
  • There has to be a feasible method to test these
    materials for their response to the severe
    conditions. This has evolved to be the
    International Fusion Materials Irradiation
    Facility (IFMIF).
  • The severe conditions of a reactor result in many
    environmental and safety concerns. We will offer
    a brief introduction to the safety issues
    associated with the materials used in fusion
    reactors.

25
IFMIF An Overview
  • Currently there is no reliable source of
    high-flux neutrons that can be used for research
    of structural materials.
  • It is an accelerator-based neutron source used to
    test specimen miniaturization technology as well
    as irradiation damage theory and modeling.
  • Working together, the European, Japan, the United
    States and the Russian Federation (as an
    associated member) an IEA and IFMIF Conceptual
    Design Activity (CDA) was established in 1995.
  • The construction of IFMIF is expected to commence
    in 2017. This means that it is unlikely to be
    useful to the design and implementation of ITER.
    A location has yet to be decided, but the
    facility will consist of the IFMIF buildings, the
    accelerator and power supply building, and the
    target and test operation building.

26
IFMIF Goals
  • Contribute to the understanding of the behavior
    of materials.
  • Develop materials by controlling composition and
    microstructure
  • Provide material technology for fabrication of
    reactors.

27
IFMIFTechnicalities
  • Capable of producing 14.6 MeV peak generation!
  • This takes 40MeV of neutron particles.
  • The footprint of the beam is 20 centimeters long
    by 5 centimeters, with a distribution of flux
    across the area.
  • Radiation beams at 20 degree angle.

28
IFMIF Facility Requirements
  • Neutron flux to volume ratio 2 MW/m2 per volume.
  • Neutron spectrum must meet First Wall neutron
    spectrum as closely as possible.
  • Neutron fluence accumulation of 150 dpa in a few
    years
  • Neutron flux gradient less than 10.
  • Machine availability.
  • Time structure.

29
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30
IFMIFWhat Might Kill Us
  • Decay Heat
  • Inventory-Based Activation Hazard
  • Oxidation Driven Activation Product Mobilization
  • Tritium Inventory
  • Chemical Reactivity with water
  • Disruption Tolerance
  • Activation
  • Reactivity
  • On that happy note

31
Research at MIT
  • Ronald G. Ballinger, Course 3 and 22
  • As a result of our research, new materials have
    been developed that allow either the mass of the
    magnet to be reduced for the same field strength
    as previous designs or higher fields to be
    developed for the same size of previous designs.
    Cost savings on the order of 25-40 can be
    achieved. These developments have placed our
    laboratory in the forefront of materials
    development for superconducting magnets.

32
Research at MIT
  • Linn W. Hobbs, Course 3 and 22
  • We are investigating why some crystals are
    stable against amorphization, while others
    amorphize easily, and involved in designing
    crystal structures and compositions (such as
    zirconate pyrochlores and oxide spinels) that are
    especially resistant to amorphization. We are
    also studying the atomic structure of
    radiation-amorphized crystals using diffraction
    techniques and molecular dynamics modeling and
    the atomic rearrangements in counterpart glasses
    in displacive radiation fields.

33
Developing Materials for Fusion Power, A Summary
  • Why?
  • Applications
  • Current Research
  • Development Strategies
  • Testing
  • Concerns
  • Research at MIT

34
References
  • Ehrlich, K., Bloom, E.E., Kondo, T.
    International strategy for fusion materials
    development. J. Nucl. Mater. 79-88 (2000).
  • Ehrilich, Karl, Mosland, Anton. IFMIF An
    international fusion materials irradiation
    facility. Elsevier Science B.V. (1998)
  • IFMIF, Facilities. lthttp//www.frascati.enea.it/if
    mif/gt. (2007)
  • Petti, D.A., McCarthy, K.A., Gulden, W.,Piet,
    S.J., Seki, Y., Kolbasov, B.. An overview of
    safety and environmental considerations in the
    selection of materials for fusion facilities.
    Elservier Science B.V. (1996)

35
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