Assessment of Blanket Options for Magnetic Diversion Concept

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Assessment of Blanket Options for Magnetic
Diversion Concept

• A. René Raffray
• UCSD
• With contributions from M. Sawan (UW), I.
  Sviatoslavsky (UW) and X. Wang (UCSD)
• HAPL Meeting
• NRL
• Washington, DC
• March 3-4, 2005

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Outline

• Impact of magnetic diversion on blanket design
  requirements
• Magnetic field impact on liquid breeders
• Reduced FW heat flux impact on He-cooled ceramic
  breeder option
• Summary

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Magnetic Diversion Impact on Blanket Design
Requirements
Example 60-Beams Illumination Configuration
Geometry results in a split blanket, the lower
part being serviced from the bottom and the top
part supported by a bridge spanning over the ion
collector plate location and serviced from the
top. Reduced heat flux on FW (only X-ray
energy deposition) eases FW coolant requirements
and opens up possibility of blanket
options - Liquid breeder (Li, Pb-17Li, Flibe
molten salt) - Perhaps He-cooled ceramic
breeder However, MHD effects introduced
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MHD Effects in Conducting Liquid Flow in a
Magnetic Field Depends on Hartmann Number, Wall
Conductance Ratio and Relative Directions of
Liquid Flow and Magnetic Field
Hartmann Number, H (ratio of magnetic to ordinary
viscosity)
Conducting side walls
Wall Conductance Ratio
b
v
Simple Estimate of MHD Pressure Drop in a Channel
B
a
Normal laminar flow pressure gradient
From M. A. Hoffman and G. A. Carlson, Magnetic
Field Effects in Fusion Reactor Blankets,
Proceedings of the 13th Intersociety Energy
Conversion Energy Conference, SAE P-75, IEEE
78-CH1372, San Diego (Aug. 20-25, 1978) 1096-1108.
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MHD Effects Include Flow Laminarization (and
reduced heat transfer at the wall) and Increased
Pressure Drop
Non-dimensionalized Hartmann pressure gradient as
a function of Hartmann No. and wall conductance
ratio for circular pipe
Laminar-to-Turbulent Transition Re as a Function
of Hartmann No.
Transverse magnetic field
Parallel magnetic field
Non-MHD transition Re 2300
Non-MHD laminar flow non-dimensionalized pressure
gradient 8 for circular pipes
From M. A. Hoffman and G. A. Carlson, Magnetic
Field Effects in Fusion Reactor Blankets,
Proceedings of the 13th Intersociety Energy
Conversion Energy Conference, SAE P-75, IEEE
78-CH1372, San Diego, (Aug. 20-25, 1978),
1096-1108.
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Simple Liquid Breeder Blanket Options for
Preliminary Analysis

• Low FW heat flux simple annular module design
  with liquid breeder slowly flowing in a 2-pass
  configuration first through the annular region
  and then through the inner channel.
• Simple estimate of MHD pressure drop for
  annular channel configuration
• - Rchamb 6.5 m fusion power 1750 MW
• - Magnetic field from cusp magnets will be at
  variable orientation to coolant flow but
  transverse B assumed to be conservative
  (larger effect).
• - However, additional losses due to the flow
  turning and also to entry and outlet effect
  in annular manifold not included.
• - Constant annular channel dimensions are
  assumed dhyd,outer 9.5 cm dhyd,inner
  23 cm
• (geometry effects would result in smaller
  channels at each end and higher pressure
  drop).
• - Li, Pb-17Li and flibe molten salt considered
  with and without an insulating layer.

Illustration of Possible Liquid Breeder Concept
for Upper and Lower Blanket Units
Annular submodule concept with a first-pass in
the annular region and a second pass in the inner
channel (insulation layer could be used to reduce
MHD effects)
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Simple MHD DP Comparison of Liquid Breeder
Blanket Options

• Results indicate possible need for insulation
  for Li and Pb-17Li (in particular for Bgt1 T and
  smaller channels).
• Flibe looks attractive based on the low MHD
  pressure drop but a significant RD
  program would be required to address other
  material issues since it is not being
  much considered elsewhere.

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Ceramic Breeder Blanket Module Configuration
(revisited with very low FW heat flux)
Preferable to couple to a Brayton cycle to
avoid accident scenario that could result in
Be/steam reaction and would require designing
the module box to accommodate high
pressure Li4SiO4 or Li2TiO3 as possible CB
Initial number and thicknesses of Be and CB
regions optimized for TBR1.1 based
on - Tmax,Be lt 750C - Tmax,CB lt
950C - kBe8 W/m-K - kCB1.2 W/m-K - dCB
region gt 0.8 cm 6 Be regions 10 CB regions
for a total module radial thickness of 0.65 m
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Magnetic Diversion Results in Major Reduction in
FW Heat Flux (photons only v. ionsphotons)
- Much reduced demand on first wall cooling
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Brayton Cycle Configuration Considered in
Combination with CB Blanket Intermediate HX to
Provide Flexibility for Separately Setting Cycle
He Fractional Pressure Drop

• 3 Compressor stages (with 2 intercoolers) 1
  turbine stage DP/P0.05 1.5 lt rplt 3.0
• - DTHX 30C
• - hcomp 0.89
• - hturb 0.93
• - Effect.recup 0.95

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Example Optimization Study of CB Blanket and
Brayton Cycle For Cases With and Without Magnetic
Diversion
Maximum cycle efficiency (h) as a function of
chamber radius (R) under the following assumed
constraints Be and CB - Tmax,Be lt
750C - Tmax,CB lt 950C - Dblkt 0.65 m for
breeding FS 1. Tmax,ODS-FS lt 700C Fusion
Power 1. 1800 MW w/o magnetic diversion and
2. 1750 MW w magnetic diversion Coolant - D
THX 30C - Ppump/Pthermal lt 0.05
Magnetic diversion results in substantial
increase ion h, which peaks at 45 as
compared to 36 for case w/o magnetic
diversion FW cooling while maintaining the
ODS-FS lt 700C imposes a major constraint in
the case w/o magnetic diversion
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Corresponding He Coolant Inlet and Outlet
Temperatures
Maximum allowable temperature of FS limits the
combination of outlet and inlet He coolant
temperatures for case w/o magnetic
diversion For case with magnetic diversion,
limits on coolant plate FS, CB and Be interplay
to limit the combination of outlet and inlet He
coolant temperatures
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Summary

• Results indicate possible need for insulation
  for Li and Pb-17Li (in particular for Bgt1 T and
  smaller channels)
• - Lose traditional advantage of magnet-less IFE
  over MFE
• Flibe looks attractive based on the low MHD
  pressure drop but a significant RD program would
  be required to address other material issues
  since it is not being much considered elsewhere.
• Magnetic diversion results in substantial
  increase in h, which peaks at 45 as compared
  to 36 for case w/o magnetic diversion
• - FW cooling while maintaining the ODS-FS lt
  700C imposes a major constraint in the case
  w/o magnetic diversion
• Future effort will focus on
• - Finishing scoping study of different options
  for original configuration (large chamber)
  and showing comparative assessment and selection
  for more detailed study
• - Development and more detailed study of
  blanket options and design for magnetic
  diversion case
• - How to balance the effort between the two?