ARIESAT Blanket and Divertor

1
ARIES-AT Blanket and Divertor

• A. R. Raffray1, 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
• Presented at the 14th ANS Topical Meeting on the
  Technology of Fusion Energy
• Park City, Utah
• October 16-19, 2000

2
Presentation Highlights How Design Was Developed
to Meet Overall Objective
Outline Power Cycle Material ARIES-AT
Reactor Blanket Design and Analysis Divertor
Design and Analysis Fabrication Conclusions

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
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

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 Max. Cycle He
Temperature 1050C Cycle efficiency 0.585
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
4
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, submitted to Fusion Engineering
Design, August 2000 From ARIES-I
5
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
6
Cross-Section and Plan View of ARIES-AT Showing
Power Core Components
7
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)
8
Poloidal Distribution of Surface Heat Flux and
Neutron Wall Load
9
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
10
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
11
Detailed Stress Analysis of Blanket Module to
Maintain Conservative Margins as Reliability
Measure
e.g. Stress Analysis of Outboard Module 6
modules per outboard segment Side walls of
all inner modules are pressure balanced except
for outer modules 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 The maximum pressure stress thermal
stress at the first wall 60113 MPa.
12
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)

Outlet Pb-17LiManifold
SiCf/SiC Poloidal Channels
Tungsten Armor
Inlet Pb-17LiManifold
13
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
14
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 Max. W Temp. 1150C Max.
SiCf/ SiC Temp. 970C
15
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
16
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
17
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.
18
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 TOFE
19
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
  3550 MPa
• SiC/SiC Pressure Thermal Stress
  35160 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

20
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,
  lifetime
• MHD effects in particular for the divertor