July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 1 ARIES-AT Blanket and Divertor Design Presented by

July 4, 2001A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France

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, USA2University of Wisconsin, Fusion Technology Institute, 1500 Engineering Drive, Madison, WI 53706-1687, USA

3Forschungszentrum Karlsruhe, Postfach 3640, D-76021 Karlsruhe, Germany

Meeting on Fusion Blanket Designs using SiCf/SiC as Structural Material

SNECMA, Bordeaux

July 4, 2001


2

Presentation Highlights How Design Was Developed to Meet Overall Objective

Outline

• Power Cycle• Material• ARIES-AT Reactor• Coolant Routing• Blanket Design and Analysis• Divertor Design and Analysis• Fabrication• Maintenance• Manifolding Analysis• 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

RecuperatorIntercooler 1Intercooler 2

Compressor 1

Compressor 2Compressor 3

HeatRejection

HX

Wnet

Turbine

IntermediateHX

5'

1

22'

38

9

4

7'9'

10

6

T

S

1

2

3

4

5 6 7 8

9 10

PbLi Divertor +Blanket Coolant

Advanced Brayton Cycle Parameters Based on Present or Near Term Technology Evolved

with Expert Input from General Atomics* • Min. He Temp. in cycle = 35°C• 3-stage compression with 2 inter-coolers• Turbine efficiency = 0.93• Compressor efficiency = 0.88• Recuperator effectiveness = 0.96• Cycle He fractional P = 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


4

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. = 1050°C

• Total compression ratio = 3

• Cycle efficiency = 0.585

• Cycle He temp. at HX inlet = 604°C

• Pb-17 Inlet temp. to power core = 650°C


5

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 ≈ 1000°C

• 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 TOFE3See: 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


6

ARIES-AT Machine and Power Parameters1,2

Power and Neutronics3 ParametersFusion Power 1719 MW

Neutron Power 1375 MW

Alpha Power 344 MW

Current Drive Power 25 MW

Overall Energy Multiplicat. 1.1

Tritium 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 GeometryMajor 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 FieldOn-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 TOFE2R. L. Miller and the ARIES Team, “Systems Context of the ARIES-AT Conceptual Fusion Power Plant,” 14th ANS Top. Meet. On TOFE3L. A. El-Guebaly and the ARIES Team, “Nuclear Performance Assessment for ARIES-AT Power Plant,” 14th ANS Top. Meet. On TOFE


7

Cross-Section and Plan View (1/6 sector) of ARIES-AT Showing Power Core Components


8

Coolant Routing Through 5 Circuits Serviced by Annular Ring Header (I)

LiPb CoolantInlet Temperature 654°COutlet Temperature 1100°C Blanket Inlet Pressure 1 MPa Divertor Inlet Pressure 1.8 MPa Mass Flow Rate 22,700 kg/s

Circuit 1 - Lower Divertor + IB Blkt RegionThermal Power and Mass Flow Rate:

501 MW and 6100 kg/sCircuit 2 - Upper Divertor + 1/2 OB Blanket I

598 MW and 7270 kg/sCircuit 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

Circuit 1: Lower Divertor + IB Blanket


9

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


10

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


11

ARIES-AT Blanket Utilizes a 2-Pass Coolant Approach to Uncouple Structure Temperature from

Outlet Coolant Temperature

Maintain blanket SiCf/SiC temperature (~1000°C) < Pb-17Li outlet temperature (~1100°C)

ARIES-AT Outboard Blanket Segment Configuration


12

Poloidal Distribution of Surface Heat Flux and Neutron Wall Load

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Poloidal Distance from Lower Outboard (m)

Assuming 10% divertortransport power re-radiation

Assuming no radiationfrom divertor

OUTBOARD INBOARD

DIV.

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

5.50

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Poloidal Distance from Lower Outboard (m)

OUTBOARD INBOARD

DIV.

Average Neutron Wall Load = 3.19 MW/m2


13

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

q''plasma

Pb-17Li

q'''LiPb

Out

q''back

vback

vFW

Poloidal

Radial

InnerChannel

First WallChannel

SiC/SiCFirst Wall SiC/SiC Inner Wall


14

Temperature Distribution in ARIES-AT Blanket Based on Moving Coordinate Analysis

Pb-17Li InletTemp. = 764 °C

Pb-17Li Outlet Temp. = 1100 °C

Max. SiC/PbLi Interf. Temp. = 994 °C

FW Max. CVD and SiC/SiC Temp. = 1009°C° and 996°C°

700

800

900

1000

1100

1200800

900

1000

1100

1200

1

2

3

4

5

6

00.020.040.060.080.1

00.020.040.060.080.1

Radial distance (m)

Poloidaldistance(m)

SiC/SiC

Pb-17Li

• 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


15

Pressure Stress Analysis of Outer Shell of Blanket Module (Max. = 85 MPa)

Thermal Stress Distribution in Toroidal Half of Outboard Blanket Module(Max. = 113 MPa)

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 << 190 MPa limit

• The maximum pressure stress + thermal stress at the first wall ~60+113 MPa.


16

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 (<<190 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.


17

Reference Divertor Design Utilizes Pb-17Li as Coolant

• 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)

Outboard Divertor PlateOutlet Pb-17LiManifold

Inlet Pb-17LiManifold

Tungsten Armor

SiCf/SiC Poloidal Channels


18

ARIES-AT Divertor Configuration and Pb-17Li Cooling Scheme

LiPb Poloidal Flow in ARIES-ATDivertor Header

PoloidalDirection

ToroidalDirection

Example schematic illustrationof 2-toroidal-pass schemefor divertor PFC cooling

Plasma q''

A ACross-Section A-A

Accommodating MHD Effects:• Minimize Interaction Parameter (<1) (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


19

Temperature Distribution in Outer Divertor PFC Channel Assuming MHD-Laminarized LiPb Flow

δBTPFC

LiPb LiPb

• 2-D Moving Coordinate Analysis• Inlet temperature = 653°C• 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

700

800

900

1000

1100

1200

600

700

800

900

1000

1100

0

0.005

0.01

0.015

0.02

00.001

0.0020.003

0.0040.005

0.0010.002

0.0030.004

0.0050.006

600

700

800

900

1000

1100

1200

Radial distance (m)

Toroidal distance (m)Tungsten

SiC/SiC

LiPbMax. W Temp. = 1150°C

Max. SiCf/ SiC Temp. = 970°C


20

Divertor Channel Geometry Optimized for Acceptable Stress and Pressure

Drop

0.00

0.50

1.00

1.50

2.00

0 0.01 0.02 0.03 0.04 0.05

Toroidal Dimension of Divertor Channel (m)

Inner Channel

Orifice

PFC Channel

Total

δBTPFC

LiPb LiPb

• 2-cm toroidal dimension and 2.5 mm minimum W thickness selected (+ 1mm sacrificial layer)

• SiCf/SiC thermal + pressure stress ~ 160+30 MPa • P minimized to ~0.55/0.7 MPa for lower/upper

divertor

Pressure Stress

Thermal Stress


21

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;

Develop Plausible Fabrication Procedures and Minimize Joints in High Irradiation Region

Brazing procedure selected for reliable joint contact area


22

ARIES-AT First Outboard Region Blanket: Proposed 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.


23

Proposed Fabrication Procedure of ARIES-AT Divertor Plate

1. Manufacture individual rectangular divertor tubes by SiCf weaving and SiC Chemical Vapor Infiltration (CVI) or polymer process, including grooves for inner”T” coolant guide;

2. Manufacture inner”T” coolant guide by SiCf weaving and SiC Chemical Vapor Infiltration (CVI) or polymer process (leave inlet feeding holes or machine them afterwards)

3. Slide inner”T” flow separator in each channel along grooves;

4. Braze the all channels together forming divertor plate;


24

Proposed Fabrication Procedure of ARIES-AT Divertor Plate (cont.)

5. Braze end caps and manifolds at each end of divertor;

6. Coat 3-mm W layer on plasma facing side (e.g. by vapor deposition followed by brazing)

Outlet Pb-17LiManifold

Inlet Pb-17LiManifold

Tungsten Armor

SiCf/SiC Poloidal Channels


25

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

• All Lifetime Components Except for: Divertor, IB Blanket, and OB Blanket I


26

Manifolding Analysis

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

Pb-17LiInlet

Pb-17LiOutlet

riro

q''

• Can the manifold be designed to maintain Pb-17Li /SiC Tinterface< Pb-17Li Toutlet while maintaining reasonable P?

• Use manifold between ring header and outboard blanket I as example


27

Pb-17Li/SiC Tinterface, Pb-17Li TBulk due to Heat Transfer in SiCf/SiC Annular Piping, and P 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 < Pb-17Li Toutlet

• However, manifold flow in region with very low or no radiation• Set manifold annular dimensions to minimize Tbulk while maintaining a reasonable P


28

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. 996°C

• Maximum CVD SiC Temp. (°C) 1009 °C

• Max. LiPb/SiC Interface Temp. 994°C

• 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) 970/950°C• Maximum W Temp. (Lower/Upper) 1145/1125°C• W Pressure + Thermal Stress ~30+50 MPa• SiC/SiC Pressure + Thermal Stress ~30+160 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


29

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 R&D 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


30

http://aries.ucsd.edu/

For More Information and Documentation on ARIES-AT and Other ARIES Studies

Please see the ARIES web site:


31

Alternative Option for Fabricating and Brazing ARIES-AT Blanket Segment

E.g. First Outboard Region Blanket Segment

1. Manufacture separate poloidal 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. Insert free-floating inner shell between two outer shell halves;

4. Braze the two half outer shells together with the braze junction toward the back of the segment to minimize neutron fluence effects;

5. As before….

If it is not possible to fabricate SiCf/SiC in tubular form:

A A

Section A-A

Documents

July 4, 2001 A. R. Raffray, et al., ARIES-AT Blanket and Divertor Design, SNECMA, Bordeaux, France 1 ARIES-AT Blanket and Divertor Design Presented by