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Title: Fusion Science and Technology Mohamed Abdou, Neil Morley, Alice Ying Mechanical and Aerospace Engineering Dept. CESTAR: Center for Energy Science and Technology Advanced Research


1
Fusion Science and TechnologyMohamed Abdou,
Neil Morley, Alice YingMechanical and Aerospace
Engineering Dept.CESTAR Center for Energy
Science and Technology Advanced Research
WEB SITE http//www.fusion.ucla.edu/
Presentation at KAIST/UCLA Joint Workshop,
January 13-14, 2005
2
Fusion Science and Technology at UCLA
  • Fusion Research is exciting and active worldwide
  • UCLA has strong research programs in plasma
    physics, fusion science and technology
  • The largest part of the Fusion Science and
    Technology Research at UCLA is in the Mechanical
    and Aerospace Engineering Department
  • UCLA leads the US program in Fusion Nuclear
    Technology
  • We already have strong international
    collaborative programs with Europe, Japanese
    Universities, JAERI, Korea (KAIST and KAERI),
    China, and Russia
  • Our research involves many technical disciplines
    fluid mechanics, heat transfer, MHD, tritium
    transport, neutronics, materials, structural
    mechanics
  • We have constructed world-class experimental
    facilities. Many students do their Ph.D. research
    in these facilities. The facilities also attract
    important international collaborations

3
Introduction
4
Incentives for Developing Fusion
  • Fusion powers the Sun and the stars
  • It is now within reach for use on Earth
  • In the fusion process lighter elements are
    fused together, making heavier elements and
    producing prodigious amounts of energy
  • Fusion offers very attractive features
  • Sustainable energy source
  • (for DT cycle provided that Breeding Blankets
    are successfully developed)
  • No emission of Greenhouse or other polluting
    gases
  • No risk of a severe accident
  • No long-lived radioactive waste
  • Fusion energy can be used to produce electricity
    and hydrogen, and for desalination

5
The Deuterium-Tritium (D-T) Cycle
  • World Program is focused on the D-T cycle
    (easiest to ignite)
  • D T ? n a 17.58 MeV
  • The fusion energy (17.58 MeV per reaction)
    appears as Kinetic Energy of neutrons (14.06 MeV)
    and alphas (3.52 MeV)
  • Tritium does not exist in nature! Decay half-life
    is 12.3 years
  • (Tritium must be generated inside the fusion
    system to have a sustainable fuel cycle)
  • The only possibility to adequately breed tritium
    is through neutron interactions with lithium
  • Lithium, in some form, must be used in the fusion
    system

6
Fusion Nuclear Technology (FNT)
Fusion Power Fuel Cycle Technology
FNT Components from the edge of the Plasma to TF
Coils (Reactor Core)
1. Blanket Components
2. Plasma Interactive and High Heat Flux
Components
a. divertor, limiter
b. rf antennas, launchers, wave guides, etc.
3. Vacuum Vessel Shield Components
Other Components affected by the Nuclear
Environment
4. Tritium Processing Systems
5. Instrumentation and Control Systems
6. Remote Maintenance Components
7. Heat Transport and Power Conversion Systems
7
Shield
Vacuum vessel
First Wall
Coolant for energy conversion
Magnets
Tritium breeding zone
8
(No Transcript)
9
Blanket Concepts(many concepts proposed
worldwide)
  • Solid Breeder Concepts
  • Always separately cooled
  • Solid Breeder Lithium Ceramic (Li2O, Li4SiO4,
    Li2TiO3, Li2ZrO3)
  • Coolant Helium or Water
  • Liquid Breeder Concepts
  • Liquid breeder can be
  • a) Liquid metal (high conductivity, low Pr) Li,
    or 83Pb 17Li
  • b) Molten salt (low conductivity, high Pr)
    Flibe (LiF)n (BeF2),
    Flinabe (LiF-BeF2-NaF)
  • B.1. Self-Cooled
  • Liquid breeder is circulated at high enough speed
    to also serve as coolant
  • B.2. Separately Cooled
  • A separate coolant is used (e.g., helium)
  • The breeder is circulated only at low speed for
    tritium extraction
  • B.3. Dual Coolant
  • FW and structure are cooled with separate coolant
    (He)
  • Breeding zone is self-cooled

10
A Helium-Cooled Li-Ceramic Breeder Concept
Example
  • Material Functions
  • Beryllium (pebble bed) for neutron multiplication
  • Ceramic breeder (Li4SiO4, Li2TiO3, Li2O, etc.)
    for tritium breeding
  • Helium purge (low pressure) to remove tritium
    through the interconnected porosity in ceramic
    breeder
  • High pressure Helium cooling in structure
    (ferritic steel)

Several configurations exist (e.g. wall parallel
or head on breeder/Be arrangements)
11
Liquid Breeder Blanket Concepts
  • Self-Cooled
  • Liquid breeder circulated at high speed to serve
    as coolant
  • Concepts Li/V, Flibe/advanced ferritic,
    flinabe/FS
  • Separately Cooled
  • A separate coolant, typically helium, is used.
    The breeder is circulated at low speed for
    tritium extraction.
  • Concepts LiPb/He/FS, Li/He/FS
  • Dual Coolant
  • First Wall (highest heat flux region) and
    structure are cooled with a separate coolant
    (helium). The idea is to keep the temperature of
    the structure (ferritic steel) below 550ºC, and
    the interface temperature below 480ºC.
  • The liquid breeder is self-cooled i.e., in the
    breeder region, the liquid serves as breeder and
    coolant. The temperature of the breeder can be
    kept higher than the structure temperature
    through design, leading to higher thermal
    efficiency.

12
Flows of electrically conducting coolants will
experience complicated magnetohydrodynamic (MHD)
effects
  • What is magnetohydrodynamics (MHD)?
  • Motion of a conductor in a magnetic field
    produces an EMF that can induce current in the
    liquid. This must be added to Ohms law
  • Any induced current in the liquid results in an
    additional body force in the liquid that usually
    opposes the motion. This body force must be
    included in the Navier-Stokes equation of motion
  • For liquid metal coolant, this body force can
    have dramatic impact on the flow e.g. enormous
    MHD drag, highly distorted velocity profiles,
    non-uniform flow distribution, modified or
    suppressed turbulent fluctuations

13
Large MHD drag results in large MHD pressure drop
Conducting walls
Insulated wall
Lines of current enter the low resistance wall
leads to very high induced current and high
pressure drop All current must close in the
liquid near the wall net drag from jxB force is
zero
  • Net JxB body force ?p c?VB2 where c (tw
    ?w)/(a ?)
  • For high magnetic field and high speed
    (self-cooled LM concepts in inboard region) the
    pressure drop is large
  • The resulting stresses on the wall exceed the
    allowable stress for candidate structural
    materials
  • Perfect insulators make the net MHD body force
    zero
  • But insulator coating crack tolerance is very low
    (10-7).
  • It appears impossible to develop practical
    insulators under fusion environment conditions
    with large temperature, stress, and radiation
    gradients
  • Self-healing coatings have been proposed but none
    has yet been found (research is on-going)

14
ITER
15
U.S. In-kind Contributions to ITER
4 of 7 Central Solenoid modules
Steady-state power supplies
15 of port-based diagnostic packages
44 of ICRH Antenna, plus all transmission
lines, RF-sources, power supplies
Start-up gyrotrons, all transmission lines, and
power supplies
Test Blanket Module
Tokamak exhaust processing system
Roughing pumps, standard components
Cooling for Divertor and Vacuum Vessel
Baffle
Pellet Injector
16
ITER Provides the First Integrated Experimental
Conditions for Fusion Technology Testing
  • Simulation of all Environmental Conditions
  • Neutrons Plasma Particles
  • Electromagnetics Tritium
  • Vacuum Synergistic Effects
  • Correct Neutron Spectrum (heating profile)
  • Large Volume of Test Vehicle
  • Large Total Volume, Surface Area of Test Matrix

17
Blanket Concepts for ITER-TBM Selected by the
Various Parties
  • Solid Breeders
  • He/SB/Be/FS All parties are strongly interested
  • H2O/SB/Be/FS Only Japan (some interest from
    China)
  • Liquid Breeders
  • He/LiPb/FS (Separately cooled) EU lead (one of
    two main concepts for EU, interest from other
    parties)
  • Dual Coolant (He/LiPb/FS with SiC) US lead,
    strong interest from EU and other parties
  • Li/V (Self-cooled) Russia is main advocate (but
    no significant resources on RD!)
  • Molten Salts US and Japanese Universities want
    the option to decide later whether to test
  • He/Li/FS Koreas proposal

18
Blanket Testing in ITER is one of ITERs Key
Objectives
Strong international collaboration among the ITER
Parties is underway to provide the science basis
and engineering capabilities for ITER TBMs
Bio-Shield Plug
TBM Frame Shield Plug
Cryostat Plug
Breeder Concentric Pipe
Transporter
EU HCLL Test Module
FW
Cryostat Extension
Drain Pipe
Conceptual Liquid Breeder Port Layout and
Ancillary equipment
US Solid breeder submodule
19
UCLA Activities
20
UCLA Program in Fusion Engineering Research
  • Current UCLA Research Activities
  • ITER Test Blanket Module RD
  • Molten Salt Thermofluid MHD (Jupiter-II)
  • Solid Breeder / SiC Thermomechanics (Jupiter-II)
  • Solid Breeder / Steel Thermomechanics (IEA)
  • ITER Basic Machine and Procurement Package
    Support
  • Free Surface MHD Flows for Plasma Facing
    Components
  • IFE Chamber Clearing Study

21
Experiments, Microscopic and Macroscopic Modeling
efforts simultaneously underway to Understand and
Predict Solid Breeder Blanket Pebble Bed
Thermomechanics Interactions
22
IEA collaboration on solid breeder pebble bed
time dependent thermomechanics interactions/deform
ation research
23
UCLA is collaborating on HIMAG 3D - a complex
geometry simulation code for free surface MHD
flows
  • Simulations are crucial to both understanding
    phenomena and exploring possible flow option for
    NSTX Li module
  • Problem is challenging from a number of physics
    and computational aspects requiring clever
    formulation and numerical implementation

Complex geometry Free surface flow around
cylindrical penetration
Unstable MHD velocity profiles in gradient
magnetic fields breakdown into instability
24
Complex geometry MHD codes already being applied
to DCLL blanket with SiC Flow Channel Inserts
  • 2D and 3D codes (developed for Liquid walls) have
    been modified for DCLL
  • Initial results show strong sidelayer jets at
    ?SiC 500 S/m with current DCLL design
  • 2D and 3D codes give conflicting results
    concerning flow in the stagnant gap region.
  • Code improvements and debugging, and continued
    simulations planned for FY05.

Velocity profile from 2D Simulation
Slice from 3D Simulation
Strong negative flow jet near pressure
equalization slot not seen in 3D simulation
Gap corner jets not seen in 2D simulation
25
UCLA MTOR can be for basic flow physics, free
surface and TBM module simulation experiments
  • Large magnetic volume for complex geometry
    modules
  • Higher field smaller volume regions for higher
    MHD interaction experiments
  • 30 liter gallium alloy flowloop

MTOR LM-MHD Facility
26
Experiments on film flows show formation of 2D
turbulence structures
  • Turbulent fluctuations organize into 2D
    structures with vorticity along the magnetic
    field
  • Corner vortices and small surface disturbances
    suppressed
  • Flow can Pinch-IN in field gradients and separate
    from the wall
  • Drag can be severe, slowing film down by 2x or 3x

U
B
27
Sophisticated 2-D neutronics analysis shows
testing objective can be achieved for a proposed
NT TBM
Proposed NT TBM
Tritium production profiles are nearly flat over
a reasonable distance in the toroidal direction
allowing accurate measurements be performed
JA TBM
Finding Flat nuclear heating and tritium
production profiles allow two designs to be
evaluated in a ¼ port submodule
28
Pulsed electro-thermal plasma gun facility
provides extreme high heat flux capability for
IFE super-heated vapor condensation study
29
Possibilities for Collaboration
30
Excellent opportunities exist for collaboration
between US and Korea on fusion engineering
  • US has extensive experience in fusion blanket
    systems developed over 30 years
  • US has focused blanket RD on key areas of
    blanket feasibility
  • Korea has strong background in fission and now
    fusion technology systems
  • Korea has strong industrial and manufacturing
    capabilities
  • Collaboration possibilities are numerous,
    especially on development and deployment of ITER
    TBMs of joint interest.

31
Possibilities for US-Korea Collaboration on
Helium-Cooled Ceramic Breeder Blankets
  • Development and characterisation of ceramic
    breeder and beryllium pebbles
  • Thermo-mechanics of pebble beds
  • Tritium release characteristics of ceramic
    breeders and beryllium
  • Beryllium behaviour under irradiation
  • Helium cooling technology
  • Prototypical mock-up testing in out-of-pile
    facility
  • In-pile testing of sub-modules
  • Development of instrumentation

32
Possibilities for US-Korea Collaboration on
Liquid Metal Breeder Blankets
  • Fabrication techniques for SiC Inserts
  • MHD and thermalhydraulic experiments on SiC flow
    channel inserts with Pb-Li alloy
  • Pb-Li and Helium loop technology and out-of-pile
    test facilities
  • MHD-Computational Fluid Dynamics simulation
  • Tritium permeation barriers
  • Corrosion experiments
  • Test modules design, fabrication with RAFS,
    preliminary testing
  • Instrumentation for nuclear environment
  • Similar possibilities exist also for molten-salt
    blankets
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