Summary of Major Features of ARIESST and ARIESAT Blanket Designs

1
Summary of Major Features of ARIES-ST and
ARIES-AT Blanket Designs

• Presented by A. René Raffray
• University of California, San Diego
• with the Contribution of the ARIES Team and S.
  Malang
• APEX Meeting, SNL, Albuquerque
• November 15, 2000
• For more information see http//aries.ucsd.edu/

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Unique Features of ARIES-ST Power Plant Include
Use of water coolant in the power core (for the
Cu centerpost) strongly discourages the use of
reactive materials such as Li and Be High
power cycle h is needed to offset the effect of
high recirculating power in the normal-conducting
TF system Relatively high power density
results from very high plasma beta The absence
of space on the inboard side for a breeding
blanket places additional constraints on material
selection and dimensions The highly elongated
plasma together with an integrated outboard TF
shell and vacuum vessel led to a vertical
maintenance scheme and toroidally integrated
blanket
3
ARIES-ST Power Parameters
Fusion Power 2859 MW Neutron Power
2287 MW Alpha Power 572
MW Total Thermal Power 3107 MW Ave. FW
Surf. Heat Flux 0.46 MW/m2 Max. FW Surf. Heat
0.6 MW/m2 Average Wall Load 4.2
MW/m2 Maximum O/B Wall Load 6.0 MW/m2
4
ARIES-ST Utilizes a Dual Coolant Approach to
Uncouple Structure Temperature from Main Coolant
Temperature
Ferritic steelPb-17LiHe Flow lower
temperature He (300- 525C) to cool structure
and higher temperature Pb-17Li (550- 700C)
for flow through blanket
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ARIES-ST Blanket Configuration
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Example Analysis of ARIES-ST First Wall
Parameters Used in the Analysis First wall
thickness 3 mm Second wall thickness 3
mm Web thickness 4 mm First wall channel
depth 25 mm Roughness of ribbed surface 45
mm Roughness of smooth surfaces 1.5 mm Coolant
pressure 12 MPa Coolant velocity 75
m/s Steel properties Thermal conductivity 26.2
W/m-K Youngs modulus 207 GPa Poissons
ratio 0.3 Thermal expansion coeff. 12x 10-6 /K
First Wall Temperature Distribution
7
Thorough Stress Analysis Confirms Stresses are
Within Allowable Values
Design condition temperature calculated code
limit peak value membrane stress (in
web) 500C 68 MPa 183 MPa (Smt) membrane plus
bending 580C 148 MPa 195 MPa (1.5 Smt) primary
plus secondary 575C 430 MPa 464 MPa (3 Sm)
First Wall Thermal Pressure Von Mises Stress
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ARIES-ST Power Core Coolant Routing(Driving a
Brayton Power Cycle)
Cycle He used to cool divertor and FW High
temperature Pb-17Li from blanket used to heat
He through IHX Power Core He
temp. 300-525C He pressure 12
MPa Pb-17Li temperature 550-700C He
flow rate 1444 kg/s Pb-17Li flow
rate 47450 kg/s He temperature to
turbine 300-680C Power cycle h gt 45
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ARIES-AT Blanket Design Objective
Develop ARIES-AT Blanket Design 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
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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

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Advanced Brayton Cycle Parameters Based on
Present or Near Term Technology Evolved with
Expert Input from General Atomics

• Min. He Temp. in cycle (heat sink) 35C
• 3-stage compression with 2 inter-coolers
• Turbine efficiency 0.93
• Compressor efficiency 0.88
• Recuperator effectiveness (advanced design)
  0.96
• Cycle He fractional DP 0.03
• Intermediate Heat Exchanger
• - Effectiveness 0.9
• - (mCp)He/(mCp)Pb-17Li 1

R. Schleicher, A. R. Raffray, C. P. Wong, "An
Assessment of the Brayton Cycle for High
Performance Power Plant," presented at the 14th
ANS Topical Meeting on Technology of Fusion
Energy, October 15-19, 2000, Park City Utah
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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
• Example Design Point
• Max. Cycle He Temperature
• 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
• Thermal Conductivity through Thickness 20
  W/m-K
• Maximum Allowable Combined Stress 190 MPa
• Maximum Allowable Operating Temperature 1000
  C
• Maximum Allowable SiC/LiPb Interface Temperature
  1000C
• Maximum Allowable SiC Burnup 34

1D. Henderson, et al, and the ARIES Team,
Activation, Decay Heat, and Waste Disposal
Analyses for ARIES-AT Power Plant," 14th TOFE 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, submitted to
Fusion Engineering Design, August 2000
From ARIES-I
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ARIES-AT Machine and Power Parameters1,2
Power and Neutronics Parameters Fusion Power
1719 MW Neutron Power 1375
MW Alpha Power 344 MW Current Drive
Power 25 MW Overall Energy Multiplicat. 1.1 T
otal 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. Meeting .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
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Cross-Section and Plan View of ARIES-AT Showing
Power Core Components
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Coolant Routing Through 5 Circuits Serviced by
Annular Ring Header
Pb-17Li Coolant Inlet Temperature 653 C Outlet
Temperature 1100 C Blanket Inlet Pressure 1
MPa Divertor Inlet Pressure 1.7 MPa Mass Flow
Rate 22,700 kg/s
Circuit Thermal Power Mass
Flow Rate 1. Lower Divertor Inboard Blanket
Region 501 MW 6100
kg/s 2. Upper Divertor 1/2 Outboard Blanket
Region I 598 MW 7270 kg/s 3.
1/2 Outboard Blanket Region I
450 MW 5470 kg/s 4. Inboard Hot Shield
1/2 Outboard Blanket II 182 MW
4270 kg/s 5. Outboard Hot Shield 1/2
Outboard Blanket II 140 MW 1700
kg/s
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ARIES-AT Utilizes a 2-Pass Coolant Approach to
Uncouple Structure Temperature from Outlet
Coolant Temperature

• ARIES-AT 2-pass Pb-17Li flow, first pass to
  cool SiCf/SiC box and second pass to superheat
  Pb-17Li
• Maintain blanket SiCf/SiC temperature (1000C) lt
  Pb-17Li outlet temperature (1100C)

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ARIES-AT Outboard Blanket Segment Configuration
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Multi-Dimensional Neutronics Analysis to
Calculate Tritium Breeding Ratio and Heat
Generation Profiles1
Latest data and code 3-D tritium breeding
gt 1.1 to account for uncertainties Blanket
configuration and zone thicknesses adjusted
accordingly Blanket volumetric heat
generation profiles used for thermal-hydraulic
analyses
1L. A. El-Guebaly and the ARIES Team, Nuclear
Performance Assessment for ARIES-AT Power Plant,
14th TOFE
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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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Pressure Stress Analysis of Inner Shell of
Blanket Module
Differential pressure stress on blanket module
inner shell varies poloidally from 0.25 MPa at
the bottom to 0 MPa at the top Maximum
pressure stress for 0.25 MPa Case - 218 MPa for
5-mm thickness - 116 MPa for 8-mm
thickness Use tapered thickness from 7 mm at
bottom to 3 mm at top to maintain comfortable
combined stress margin (ltlt 190 MPa)
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Pressure Stress Analysis of Outer Shell of
Blanket Module at Segment End of First Outboard
Region
6 modules per outboard segment Side walls
of all inner modules are pressure balanced Side
walls of outer modules 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 by tailoring the thickness to
maintain a uniform stress. This would reduce the
SiC volume fraction and benefit tritium breeding.
The thermal stress at this location is small
and the sum of the pressure and thermal stresses
is well within the 190 MPa limit. The maximum
pressure stress at the first wall is quite low,
60 MPa.
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3-D Thermal Stress Analysis of Toroidal Half of
Module in First Outboard Blanket Region
Example case Effective h in Pb-17Li channel
15 kW/m2-K Max. thermal stress 113
MPa Max. thermal stress 114 MPa Max.
combined stress 174 MPa (within the 190 MPa
limit)
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Develop Plausible Fabrication Procedure 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
L. M. Waganer, Comparing Maintenance
Approaches for Tokamak Fusion Power Plants, 14th
ANS Topical Meeting on Technology of Fusion
Energy, October 15-19, 2000, Park City Utah
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Annular Manifold Configuration with Low Temp.
Inlet Pb-17Li in Outer Channel and High Temp.
Outlet Pb-17Li in Inner Channel (e.g manifold
between ring header and outboard blanket I )
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 miminimize
DTbulk while maintaining a reasonable DP
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Typical ARIES-AT Blanket Parameters for Design
Point

• E.g. Blanket Outboard Region 1
• Number of Segments 32
• Number of Modules per Segment 6
• Module Poloidal Dimension 6.8 m
• Average Module Toroidal Dimension 0.19 m
• First Wall SiCf/SiC Thickness 4 mm
• First Wall CVD SiC Thickness 1 mm
• First Wall Annular Channel Thickness 4 mm
• Average Pb-17Li Velocity in First Wall 4.2 m/s
• First Wall Channel Re 3.9 x 105
• First Wall Channel Transverse Ha 4340
• MHD Turbulent Transition Re 2.2 x 106
• First Wall MHD Pressure Drop 0.19 MPa
• Maximum SiCf/SiC Temperature 996C
• Maximum CVD SiC Temperature 1009 C
• Maximum Pb-17Li/SiC Interface Temperature 994C
• Average Pb-17Li Velocity in Inner Channel 0.11
  m/s

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ARIES-AT Blanket Design - Conclusions

• The Blanket Design Utilizes High-Temperature
  Pb-17Li as Breeder and Coolant and SiCf/SiC
  Composite as Structural Material
• High performance (Brayton cycle efficiency 59)
• Attractive safety features (low activation
  SiCf/SiC)
• Simple design geometry
• Reasonable design margins as an indication of
  reliability
• Credible maintenance and fabrication processes
• Key RD Issues Have Been Identified, Including
• SiCf/SiC fabrication/joining, and material
  properties at high temperature and under
  irradiation, in particular
• Thermal conductivity, maximum temperature limits,
  lifetime