ARIES-AT Blanket and Divertor Design

1
ARIES-AT Blanket and Divertor Design

• Presented by A. R. Raffray1
• Contributors L. El-Guebaly2, S. Malang3, I.
  Sviatoslavsky2,
• M. S. Tillack1, X. Wang1, and the ARIES Team
• 1University of California, San Diego, 460 EBU-II,
  La Jolla, CA 92093-0417, USA
• 2University of Wisconsin, Fusion Technology
  Institute, 1500 Engineering Drive, Madison, WI
  53706-1687, USA
• 3Forschungszentrum Karlsruhe, Postfach 3640,
  D-76021 Karlsruhe, Germany
• Japan-US Workshop on Fusion Power Plants and
  Related Advanced technologies with participation
  of EU
• University of Tokyo, Japan
• March 29-31, 2001

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Presentation Highlights How Design Was Developed
to Meet Overall Objective
Overall Objective Develop ARIES-AT Blanket and
Divertor Designs to Achieve High Performance
while Maintaining Attractive safety
features Simple design geometry Reasonable
design margins as an indication of
reliability Credible maintenance and
fabrication processes Design Utilizes
High-Temperature Pb-17Li as Breeder and Coolant
and SiCf/SiC Composite as Structural Material
Outline Power Cycle Material ARIES-AT
Reactor Coolant Routing Blanket Design and
Analysis Divertor Design and Analysis Fabricat
ion Maintenance Manifolding
Analysis Conclusions
3
Brayton Cycle Offers Best Near-Term Possibility
of Power Conversion with High Efficiency

• Maximize potential gain from high temperature
  operation with SiCf/SiC
• Compatible with liquid metal blanket through use
  of IHX
• High efficiency translates in lower COE and lower
  heat load

Advanced Brayton Cycle Parameters Based on
Present or Near Term Technology Evolved with
Expert Input from General Atomics Min. He
Temp. in cycle 35C 3-stage compression with
2 inter-coolers Turbine efficiency
0.93 Compressor efficiency 0.88 Recuperator
effectiveness 0.96 Cycle He fractional DP
0.03
R. Schleicher, A. R. Raffray, C. P. Wong, "An
Assessment of the Brayton Cycle for High
Performance Power Plant," 14th ANS Top. Meet. On
TOFE
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Compression Ratio is Set for Optimum Efficiency
and Reasonable IHX He Inlet Temperature

• IHX He inlet temperature
• dictates Pb-17Li inlet
• temperature to power core
• Design Point
• Max. cycle He temp. 1050C
• Total compression ratio 3
• Cycle efficiency 0.585
• Cycle He temp. at HX inlet 604C
• Pb-17 Inlet temp. to power core 650C

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SiCf/SiC Enables High Temperature Operation and
its Low Decay Heat Helps Accommodate LOCA and
LOFA Events W/O Serious Consequences on
In-Reactor Structure1,2

• Properties Used for Design Analysis Consistent
  with Suggestions from International Town Meeting
  on SiCf/SiC Held at Oak Ridge National Laboratory
  in Jan. 20003
• Density 3200 kg/m3
• Density Factor 0.95
• Young's Modulus 200-300 GPa
• Poisson's ratio 0.16-0.18
• Thermal Expansion Coefficient 4 ppm/C
• Thermal Conductivity in Plane 20 W/m-K
• Therm. Conductivity through Thickness 20
  W/m-K
• Maximum Allowable Combined Stress 190 MPa
• Maximum Allowable Operating Temperature 1000
  C
• Max. Allowable SiC/LiPb Interface Temperature
  1000C
• Maximum Allowable SiC Burnup 3

1D. Henderson, et al, and the ARIES Team,
Activation, Decay Heat, and Waste Disposal
Analyses for ARIES-AT Power Plant," 2E. Mogahed,
et al, and the ARIES Team, Loss of Coolant and
Loss of Flow Analyses for ARIES-AT Power Plant,"
14th ANS T. M. On TOFE 3See http//aries.ucsd.edu
/PUBLIC/SiCSiC/, also A. R. Raffray, et al.,
Design Material Issues for SiCf/SiC-Based Fusion
Power Cores, to appear in Fusion Engineering
Design, 2001 From ARIES-I
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ARIES-AT Machine and Power Parameters1,2
Power and Neutronics3 Parameters Fusion Power
1719 MW Neutron Power 1375
MW Alpha Power 344 MW Current Drive
Power 25 MW Overall Energy Multiplicat. 1.1 T
ritium Breeding Ratio 1.1 Total Thermal
Power 1897 MW Ave. FW Surf. Heat Flux 0.26
MW/m2 Max. FW Surf. Heat 0.34 MW/m2 Average
Wall Load 3.2 MW/m2 Maximum O/B Wall Load
4.8 MW/m2 Maximum I/B Wall Load 3.1 MW/m2
Machine Geometry Major Radius 5.2
m Minor Radius 1.3 m FW Location at O/B
Midplane 6.5 m FW Location at Lower O/B 4.9
m I/B FW Location 3.9 m Toroidal
Magnetic Field On-axis Magnetic Field 5.9
T Magnetic Field at I/B FW 7.9 T Magnetic
Field at O/B FW 4.7 T
1F. Najmabadi, et al.and the ARIES Team, Impact
of Advanced Technologies on Fusion Power Plant
Characteristics, 14th ANS Top. M.on TOFE 2R. L.
Miller and the ARIES Team, Systems Context of
the ARIES-AT Conceptual Fusion Power Plant, 14th
ANS Top. Meet. On TOFE 3L. A. El-Guebaly and the
ARIES Team, Nuclear Performance Assessment for
ARIES-AT Power Plant, 14th ANS Top. Meet. On TOFE
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Cross-Section and Plan View (1/6 sector) of
ARIES-AT Showing Power Core Components
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Coolant Routing Through 5 Circuits Serviced by
Annular Ring Header (I)
Circuit 1 Lower Divertor IB Blanket
LiPb Coolant Inlet Temperature 654C Outlet
Temperature 1100C Blanket Inlet Pressure 1
MPa Divertor Inlet Pressure 1.8 MPa Mass Flow
Rate 22,700 kg/s Circuit 1 - Lower Divertor
IB Blkt Region Thermal Power and Mass Flow
Rate 501 MW and 6100 kg/s Circuit 2 - Upper
Divertor 1/2 OB Blanket I 598 MW and 7270
kg/s Circuit 3 - 1/2 OB Blanket I 450 MW and
5470 kg/s Circuit 4 - IB Hot Shield 1/2 OB
Blanket II 182 MW and 4270 kg/s Circuit 5 - OB
Hot Shield 1/2 OB Blanket II 140 MW and 1700
kg/s
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Coolant Routing Through 5 Circuits Serviced by
Annular Ring Header (II)
Circuit 2 Upper Divertor 1/2 OB Blanket I
Circuit 3 1/2 OB Blanket I
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Coolant Routing Through 5 Circuits Serviced by
Annular Ring Header (III)
Circuit 4 IB Hot Shield 1/2 OB Blanket II
Circuit 5 OB Hot Shield 1/2 OB Blanket II
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ARIES-AT Blanket Utilizes a 2-Pass Coolant
Approach to Uncouple Structure Temperature from
Outlet Coolant Temperature
ARIES-AT Outboard Blanket Segment Configuration
Maintain blanket SiCf/SiC temperature (1000C) lt
Pb-17Li outlet temperature (1100C)
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Poloidal Distribution of Surface Heat Flux and
Neutron Wall Load
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Moving Coordinate Analysis to Obtain Pb-17Li
Temperature Distribution in ARIES-AT First Wall
Channel and Inner Channel
Assume MHD-flow-laminarization effect Use
plasma heat flux poloidal profile Use
volumetric heat generation poloidal and radial
profiles Iterate for consistent boundary
conditions for heat flux between Pb-17Li inner
channel zone and first wall zone Calibration
with ANSYS 2-D results
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Temperature Distribution in ARIES-AT Blanket
Based on Moving Coordinate Analysis
Max. SiC/PbLi Interf. Temp. 994 C
Pb-17Li Inlet Temp. 764 C
Pb-17Li Outlet Temp. 1100 C
Pb-17Li Inlet Temp. 764 C Pb-17Li Outlet
Temp. 1100 C From Plasma Side - CVD
SiC Thickness 1 mm - SiCf/SiC Thickness 4
mm (SiCf/SiC k 20 W/m-K) - Pb-17Li
Channel Thick. 4 mm - SiC/SiC Separ. Wall
Thick. 5 mm (SiCf/SiC k 6 W/m-K)
Pb-17Li Vel. in FW Channel 4.2 m/s Pb-17Li
Vel. in Inner Chan. 0.1 m/s Plasma heat
flux profile assuming no radiation from
divertor
FW Max. CVD and SiC/SiC Temp. 1009C and
996C
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Detailed Stress Analysis of Blanket Module to
Maintain Conservative Margins as Reliability
Measure Stress Analysis of Outboard Module
6 modules per outboard segment Side walls
of all inner modules are pressure balanced except
for outermodules which must be reinforced to
accommodate the Pb-17Li pressure (1
MPa) For a 2-cm thick outer module side wall,
the maximum pressure stress 85 MPa The side
wall can be tapered radially to reduce the SiC
volume fraction and benefit tritium breeding
while maintaining a uniform stress The
thermal stress at this location is small and the
sum of the pressure and thermal stresses is ltlt
190 MPa limit The maximum pressure stress
thermal stress at the first wall 60113 MPa.
Thermal Stress Distribution in Toroidal Half of
Outboard Blanket Module (Max. s 113 MPa)
Pressure Stress Analysis of Outer Shell of
Blanket Module (Max. s 85 MPa)
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Pressure Stress Analysis of Inner Shell Shows
Comfortable Stress Limit Margin
The inner wall is designed to withstand the
difference between blanket inlet and outlet
pressures (0.25 MPa). The thickness of the
upper and lower wall is 5 mm. The maximum
stress is 116 MPa for a side-wall thickness of 8
mm (ltlt190 MPa limit) In addition, the
maximum pressure differential of 0.25 MPa occurs
at the lower poloidal location. The inner wall
thickness could be tapered down to 5 mm at the
upper poloidal location if needed to minimize the
SiC volume fraction.
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Reference Divertor Design Utilizes Pb-17Li as
Coolant
Outboard Divertor Plate

• Single power core cooling system
• Low pressure and pumping power
• Analysis indicates that proposed
  configuration can accommodate a maximum
  heat flux of
• 5-6 MW/m2
• Alternate Options
• - He-Cooled Tungsten Porous Heat Exchanger
  (ARIES-ST)
• - Liquid Wall (Sn-Li)

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ARIES-AT Divertor Configuration and Pb-17Li
Cooling Scheme
Accommodating MHD Effects Minimize
Interaction Parameter (lt1) (Strong Inertial
Effects) Flow in High Heat Flux Region
Parallel to Magnetic Field (Toroidal) Minimize
Flow Length and Residence Time Heat Transfer
Analysis Based on MHD-Laminarized Flow
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Temperature Distribution in Outer Divertor PFC
Channel Assuming MHD-Laminarized LiPb Flow
2-D Moving Coordinate Analysis Inlet
temperature 653C W thickness 3 mm SiCf/
SiC Thickness 0.5 mm Pb-17Li Channel
Thickness 2 mm SiCf/SiC Inner Wall Thick.
0.5 mm LiPb Velocity 0.35 m/s Surface Heat
Flux 5 MW/m2
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Divertor Channel Geometry Optimized for
Acceptable Stress and Pressure Drop
2-cm toroidal dimension and 2.5 mm minimum
W thickness selected ( 1mm sacrificial
layer) SiCf/SiC thermal pressure stress
16030 MPa DP minimized to 0.55/0.7 MPa
for lower/upper divertor
Pressure Stress
Thermal Stress
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Develop Plausible Fabrication Procedures and
Minimize Joints in High Irradiation Region
E.g. First Outboard Region Blanket
Segment 1. Manufacture separate halves of the
SiCf/SiC poloidal module by SiCf weaving and SiC
Chemical Vapor Infiltration (CVI) or polymer
process 2. Manufacture curved section of
inner shell in one piece by SiCf weaving and SiC
Chemical Vapor Infiltration (CVI) or polymer
process 3. Slide each outer shell half over
the free-floating inner shell 4. Braze the two
half outer shells together at the
midplane 5. Insert short straight sections of
inner shell at each end
Brazing procedure selected for reliable joint
contact area
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ARIES-AT First Outboard Region Blanket Segment
Fabrication Procedure (cont.)
6. Form a segment by brazing six modules together
(this is a bond which is not in contact with the
coolant) and 7. Braze caps at upper end and
annular manifold connections at lower end of the
segment.
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Maintenance Methods Allow for End-of-Life
Replacement of Individual Components
All Lifetime Components Except for
Divertor, IB Blanket, and OB Blanket I
L. M. Waganer, Comparing Maintenance
Approaches for Tokamak Fusion Power Plants, 14th
ANS Topical Meeting on TOFE
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Manifolding Analysis

• Annular manifold configuration with low
  temperature inlet Pb-17Li in outer channel and
  high temperature outlet Pb-17Li in inner channel

• Can the manifold be designed to maintain Pb-17Li
  /SiC Tinterfacelt Pb-17Li Toutlet while
  maintaining reasonable DP?
• Use manifold between ring header and outboard
  blanket I as example

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Pb-17Li/SiC Tinterface, Pb-17Li DTBulk due to
Heat Transfer in SiCf/SiC Annular Piping, and DP
as a Function of Inner Channel Radius
Reduction in Tinterface at the expense of
additional heat transfer from outlet Pb-17Li to
inlet Pb-17Li and increase in Pb-17Li Tinlet
Very difficult to achieve maximum Pb-17Li/SiC
Tinterface lt Pb-17Li Toutlet However, manifold
flow in region with very low or no radiation
Set manifold annular dimensions to minimize
DTbulk while maintaining a reasonable DP
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Typical Blanket and Divertor Parameters for
Design Point

• Blanket Outboard Region 1
• No. of Segments 32
• No. of Modules per Segment 6
• Module Poloidal Dimension 6.8 m
• Avg. Module Toroidal Dimen. 0.19 m
• FW SiC/SiC Thickness 4 mm
• FW CVD SiC Thickness 1 mm
• FW Annular Channel Thickness 4 mm
• Avg. LiPb Velocity in FW 4.2 m/s
• FW Channel Re 3.9 x 105
• FW Channel Transverse Ha 4340
• MHD Turbulent Transition Re 2.2 x 106
• FW MHD Pressure Drop 0.19 MPa
• Maximum SiC/SiC Temp. 996C
• Maximum CVD SiC Temp. (C) 1009 C
• Max. LiPb/SiC Interface Temp. 994C
• Avg. LiPb Vel. in Inner Channel 0.11 m/s

• Divertor
• Poloidal Dimension (Outer/Inner) 1.5/1.0 m
• Divertor Channel Toroidal Pitch 2.1 cm
• Divertor Channel Radial Dimension 3.2 cm
• No. of Divertor Channels (Outer/Inner)
  1316/1167
• SiC/Si Plasma-Side Thickness 0.5 mm
• W Thickness 3.5 mm
• PFC Channel Thickness 2 mm
• Number of Toroidal Passes 2
• Outer Div. PFC Channel V (Lower/Upper)
  0.35/0.42 m/s
• LiPb Inlet Temperature (Outer/Inner)
  653/719 C
• Pressure Drop (Lower/Upper)
  0.55/0.7 MPa
• Max. SiC/SiC Temp. (Lower/Upper) 970/950C
• Maximum W Temp. (Lower/Upper)
  1145/1125C
• W Pressure Thermal Stress
  3050 MPa
• SiC/SiC Pressure Thermal Stress
  30160 MPa
• Toroidal Dimension of Inlet and Outlet Slot 1 mm
• Vel. in Inlet Outlet Slot to PFC Channel
  0.9-1.8 m/s
• Interaction Parameter in Inlet/Outlet
  Slot 0.46-0.73

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Conclusions

• ARIES-AT Blanket and Divertor Design Based on
  High-Temperature Pb-17Li as Breeder and Coolant
  and SiCf/SiC Composite as Structural Material
• High performance
• Attractive safety features
• Simple design geometry
• Reasonable design margins as an indication of
  reliability
• Credible maintenance and fabrication processes
• Key RD Issues
• SiCf/SiC fabrication/joining, and material
  properties at high temperature and under
  irradiation including
• Thermal conductivity, maximum temperature (void
  swelling and Pb-17Li compatibility), lifetime
• MHD effects in particular for the divertor
• Pb-17Li properties at high temperature

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For More Information and Documentation on
ARIES-AT and Other ARIES Studies
Please see the ARIES web site
http//aries.ucsd.edu/