TF Coils

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The FIRE Design effort has addressed all major
subsystems issues

• TF Coils Global Structure
• Central Solenoid Poloidal Field Coils
• Vacuum Vessel
• Plasma Facing Components
• Thermal Shield
• Ion Cyclotron Heating
• Fueling Pumping
• Tritium Systems

• Neutronics Shielding
• Activation, Decay Heat Radiation Exposure
• Remote Maintenance
• Magnet Power Systems
• Cryoplant
• Facilities Siting
• Safety

-Design goals have been met or exceeded for the
baseline.  -Several options issues have been
identified. -Initial cost estimates have been
prepared. -Peer reviews have been done on
some major systems.
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FY01 Meetings and Milestones
item where date
FY01 Kick-off Meeting ANS, Park City Oct 18, 00
Design Point Subgroup PPPL Nov 29-30, 00
Cost Subgroup PPPL Dec 1, 00
Review of Physics Engineering Status NSO PAC, MIT Jan 17-18, 01
Project Peer Reviews    
TF/PF/Structures PPPL June 5-7, 01
VV, PFCs, Fueling Pumping PPPL June 5-7, 01
Nuclear Effects and Activation By mail (phone TBD) June, 01
Facilities Siting By mail phone June, 01
Power Supplies TBD FY02
ICRF Systems TBD FY02
Remote Handling Tritium TBD FY02
Final FY01 Engineering Report ------ Sept, 01
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June 5-7, 01 Review Committee Membership
C. Bushnell, Chairman Independent
J. Irby MIT
S. Majumdar ANL
P. Mioduszewski ORNL
R. Parker MIT
A. Pizzuto ENEA, Frascati
F. Puhn GA
Note Committee review report to C. Baker is on
web.
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FIRE Wedged Baseline Operation Summaryc-June 5-7,
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Configuration TF Coilsa Flat-top time, s CS Coils Max Temp, K PF Coils Max Temp, K
Baseline 10T 6.44 MA DT Power 200 MW 18.5 s with DT 26 s with DD 152 173
Higher B mode 12T, 7.7 MA DT Power 250 MW 12 s with DT 15 s with DD 161 183
TPX mode 4T 2 MA DD Power 5 MW 214 s 144 169
AT/BP mode 8T 5 MA DT Power 150 MW 31 s with DTb 46 s with DD TBD TBD
Note a) BeCu for TF coil inner leg OFHC for
balance of TF coils, CS and PF coils b)
AT mode pulse length with DT may be limited by VV
or PFC thermal limits c) meets or
exceeds engineering requirements
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Bucked and Wedged TF Coil Study

• An all OFHC, Bucked and Wedged, TF configuration
  is an option
• Max Field is lt12T to remain within the OFHC
  copper allowable stress limit
• Longer pulses are possible at a given field level
  
• Lower power requirements may increase number of
  possible sites
• TF material processing costs will be reduced
• RD for a BeCu to OFHC joint in TF plates will
  not be required
• TF fabrication assembly will be more complex to
  assure proper bucking wedging

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POWER REQUIREMENTS FOR FIRE, June 5-7, 01
BeCu TF Inner Legs
All Cu TF Coils
Field Flat-top 10T 20s 10T 20s 12T 12s 12T 12s 10T 31s 10T 31s 12T 23s 12T 23s
Peak Power (MW) Peak Energy (GJ) Peak Power (MW) Peak Energy (GJ) Peak Power (MW) Peak Energy (GJ) Peak Power (MW) Peak Energy (GJ)
TF 490 11.5 815 11.5 267 12.6 345 13.2
PF 250 2.2 360 3.7 250 5 360 4.6
RF 60 1 60 0.6 60 2.3 60 1.3
Sum 800 14.7 1235 15.8 577 19.9 765 19.1
Grid 550 12.5 600 10.9 577 19.9 404 14.5
MG 250 2.2 635 4.9 0 0 360 4.6
Significantly lower power for all Cu TF coils
reduces capital operating costs and expands the
list of candidate sites.
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FIRE Design Review Variations-June 5-7, 01
FIRE baseline FIRE FIRE FIRE
Wedged B W Wedged B W
Inner Leg Matl BeCu OFHC BeCu OFHC
Radii R(m), a(m) 2.0, 0.525 2.0, 0.525 2.14, 0.595 2.14, 0.595
Field Bt at R, (T) 10 (12) 10 (12) 10 (12) 10 (12)
Plasma Current Ip, (MPa) 6.44 (7.7) 6.44 (7.7) 7.7 (8.25) 7.7 (8.25)
Flat-top time, (sec) 20 (12) 31 (23) 20 (12) 31 (23)
TF Allowable Stress, MPa 700 300 700 300
TF VM Stress, MPa 466 (666) 230 (326) 529 (762) 230 (326)
Allowable/Actual Stress 1.5 (1.05) 1.3 (0.92) 1.3 (0.92) 1.3 (0.92)
Questions

1. What is a suitable margin for Pre-conceptual
   design?
2. What can the machines do at comparable stress
   margins?

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External Review of FIRE Design Point--
Conclusion Summary for Magnet Systems

• Critical Design Issues
• Focus on 2 designs near Q10 that have, at the
  Pre-conceptual Design level, an Engineering
  Margin of 1.2-1.3
• Then focus on 1 device, either wedged or bucked
  and wedged (to be selected by the design team)
• Incorporate design attention to the details of
  leads, both TF and CS, associated cooling systems
  design of all other critical systems that are
  lacking detail at the Pre-conceptual level
• Critical RD Issues
• Qualification of the properties of BeCu for the
  wedged design and OFHC copper for the bucked and
  wedged design in sizes and thicknesses needed for
  fabrication
• Qualification of materials for the insulation
  systems

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Estimated Machine Variations at Margins of 1.0-1.3
Wedged B W Wedged B W B W
Inner Leg Matl BeCu OFHC BeCu OFHC OFHC
Major Radius, R, m 2.0 2.0 2.14 2.14 1.86
Minor radius, m 0.525 0.525 0.595 0.595 0.488
allowable stress Max TF stress 1.0 1.3 1.5 1.0 1.2 1.3 1.0 1.2 1.3 1.0 1.2 1.3 1.0 1.2 1.3
Plasma, Current, MA 7.89 6.93 6.44 7.34 6.70 6.44 8.78 8.01 7.70 8.78 8.01 7.70 6.82 6.23 5.99
Field at R, Tesla 12.3 10.8 10.0 11.4 10.4 10.0 11.4 10.4 10.0 11.4 10.4 10.0 11.4 10.4 10.0
Flat-top, s 11.7 14.8 18.5 23.9 28.7 31.0 15.4 18.5 20.0 23.9 28.7 31.0 20.7 24.8 26.8
Question What is an appropriate margin at this
stage? June Review recommends 1.2 to
1.3
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Preliminary B W Risk Assessment

• Can a BW machine be assembled?..yes
• Is it robust wrt assembly tolerances?yes
• Issues to be resolved
• Need for a bucking cylinder
• Cooling of the Central Solenoid
• Material properties for TF conductor

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Two B W Assembly Options That Work

• High Tolerance Machining
• Machine wedge faces and nose of TF coils
• Machine the CS to a known OD
• Assemble TF array apply ring preload
• Machine TF bore
• Back-off TF coils insert CS reset TF coils
• Epoxy filled bladders and shims
• Assemble TF coils and CS with radial gap
• Use machined wedge faces or epoxy filled bladders
  at TF wedge faces
• Use epoxy filled bladders in radial gap
• (as in ITER CS Model Coil)
• Remove a shim if a gap is desired

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BW Assembly is Robust wrt Tolerances

• Elastic/Plastic Analysis Summary for 11.5 T
• Fractional mm fit-up tolerances are OK
• Off-normal fit, up to 2.5 mm, produces small
  plastic strains within the capacity of the
  conductor and insulation materials

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Wedged vs Bucked and Wedged
issue Wedged Bucked Wedged
TF/CS interaction uncoupled operation, but no mutual support has coupled operation with mutual support
Material processing costs BeCu is more expensive than OFHC
Conductor mechanical properties Require validation for thick plates Require validation for thick plates
Conductor joints Require more development Require development
TF/CS Assembly Assembly is more difficult
Power required Substantially more
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External Review of FIRE Design Point--
Conclusion Summary for VV, PFCs, Fueling
Pumping

• Critical Design Issues
• The design divertor heat load of 25 MW/m2 for the
  outer divertor is at the limit of engineering
  feasibility
• Develop a complete description of
  disruption/loads/stresses
• Consider active cooling for the inner divertor
• Determine diagnostic design RD required
• Critical RD Issues
• Determine behavior of W rods in divertor plates
  under disruption conditions (loss of melt layer,
  effects on neighboring rods, etc.)
• Optimization Issues
• Adopt the ITER Design Criteria expand as needed
• Require 104 l/s pumping speed
• Determine Cu-ss bonding method for in vessel use

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FIRE Engineering RD

• State-of-the-art materials and manufacturing
  processes will allow the highest performance to
  be achieved cost effectively.
• Several RD areas have been identified to
• -complete the material property data base to
  assure consistency with design criteria for
  materials procured in the size required for the
  device,
• -test design concepts for component manufacture
  or assembly to assure processes are sufficiently
  developed and specified, or
• -validate the design of prototype components
  through fabrication and test to assure that
  performance, cost or remote handling features
  have been adequately considered.

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Engineering RD Lists Initial Cost Estimates

• TF Conductor and Design Criteria
• TF Conductor Joints
• Radiation Resistant Electrical Insulation
• High and Low Friction Materials
• High Force, High Reliability Jacking System for
  TF coils
• First Wall and Divertor Components
• Vacuum Vessel
• Remote Handling
• Fueling and Pumping
• ICRH Antenna
• Power Supply System-tbd

Note red specifically mentioned in June
reviewers report
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1. Copper Conductor and Design Criteria

• Background
• The data base requires assessment and extension
  for plates of the size to be procured for the
  full scale TF and CS conductor. The properties
  assumed require validation for both designs.
• Inner Leg of the Wedged TF baseline design-
• C17510 BeCu (68 IACS) in thick plate (36mm) form
  is used in the inner leg. The principal stresses
  are primarily axial tension and azimuthal
  compression. Required UTS 800 MPa min. yield
  724 MPa.
• Bucked and Wedged TF alternate design-
• Design uses OFHC copper in thick plate form.
  Required 60 cold work for 300 MPa
• Central Solenoid Coil Both Wedged and Bucked and
  Wedged Alternate Design
• Both concepts use C10200 copper in thick plate
  (38mm) form. Rolled or forged copper discs are
  required to meet strength requirements. (350 MPa
  UTS 300 MPa min. yield)
• RD Task
• Obtain samples from full size plate stock and
  carry out a mechanical testing program to assure
  that static and crack growth properties at room
  and LN2 temperatures are adequate.

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2. Conductor Joint Development

• Background Both the baseline and alternate TF
  coil designs require a high strength joining
  process which does not result in an annealed
  zone.
• Baseline wedged design
• The baseline design uses C17510 BeCu for the
  inboard leg of the TF coils and C10200 copper for
  the balance of the coils. A cost effective,
  reliable high strength joining method for the
  material transition is essential.
• Bucked and wedged alternate design
• The bucked and wedged alternate TF design uses
  OFHC copper throughout the TF coil. In principal
  the turns for the latter could be cut from large
  thick plates, from which, the centers would be
  scrap. A cost effective joining method for
  joining plate segments would allow the TF legs
  to be fabricated from readily available plate
  sizes and eliminate the need to procure
  specially sized plates.
• RD Task
• Develop manufacturing processes and carry out a
  mechanical testing program to assure adequate
  mechanical properties and to validate design
  criteria for the joints. Potential candidate
  processes include friction stir welding and
  e-beam welding.

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3. Radiation Resistant Insulating Materials

• Background
• Data from the BPX insulation test program
  indicates that there are several glass/epoxy
  formulations (CTD-101 Shikazima) which can meet
  FIREs requirement for radiation exposure
  capability of 1.5 x 1010 rads.
• This is a high leverage RD item, since it has
  the potential to permit more full power D-T shots
  and may permit the experimental program to be
  expanded with possibly only a minor impact on
  costs.
• RD Task
• Develop high radiation resistant insulating
  materials with good processing characteristics
  for coil fabrication. (note several SBIRs are
  underway in this area)

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RD List for PFCs
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Conclusions

• A FIRE Wedged baseline is a reasonable choice
• A FIRE Bucked Wedged machine is a suitable
  back-up
• It can be assembled with adequate tolerances
• It is robust wrt assembly tolerances
• BW Design Issues to be resolved
• Need for a bucking cylinder
• Cooling for the CS
• RD items have been identified
• Critical Items as per review
• Material properties for conductor and insulation
• Behavior of W rods in divertor
• RD tasks require a budget and time frame!

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Back-up viewgraphsOther Engineering RD Needs
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4a. Low Friction Insulation Characterization

• Background The design of the TF and CS coil
  systems require that selected interface areas
  retain a desired level of either low or high
  friction during operation.
• Segmented Central Solenoid in both Wedged and
  Bucked Wedged Designs-
• FIRE employs a segmented CS with a variation of
  currents among the 5 coils in the stack during a
  pulse.
• Adjacent coils in the CS operate with different
  temperature and electromagnetic load profiles
  during a pulse.
• Adjacent coils will strain differently and
  relative radial motion between coils in the CS
  will occur.
• Interface must lock the coils azimuthally,
  maintain the coils co-axial, and allow relative
  radial motion with low friction.
• RD Tasks
• Prototypes of the interface areas will be
  fabricated and tested under simulated operating
  conditions to verify operation and adequate life.
  
• .

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4b. Low Friction Insulating Material for the
TF/CS Interface in Bucked Designs

• Background The CS tends to expand radially and
  compress axially during operation. The inboard
  legs of the TF coils tend to stretch vertically
  due to their in-plane loads and shift azimuthally
  due to their out-of-plane loads. In a bucked
  design a low friction interface between the TF
  and CS is desirable to limit
• the CS vertical tension imposed by the TF,
• transmission of torsional shear into the CS, and
• radial-vertical traction shear imposed on the CS
  by the TF.
• RD Task
• Select candidate materials and processes for
  application to the identified interfaces in the
  FIRE design.
• Apply low friction materials to substrates on a
  scale consistent with fabrication methods for
  FIRE.
• Perform mechanical tests to assure that expected
  surface friction performance is consistent with
  design criteria and reliable for the lifetime of
  the machine.

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4c. High Friction Insulation Characterization

• Background
• TF Coils in both Wedged and Bucked Wedged
  Designs-
• Overturning moments on the TF coils are reacted
  by wedging action at the inboard legs and by
  shear between interfaces of the outer intercoil
  structures on the TF cases.
• A friction coefficient of 0.3 is needed
  between TF inboard legs to limit torsional
  motions and between cases on the outboard side to
  reduce shear pin and bolting requirements
• RD Task
• Testing is required to verify friction
  coefficients and adequate life.

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5. Ring Preload Jacking System

• Background Both the Wedged and the Bucked and
  Wedged TF coil designs use large steel rings
  outboard of the TF coils. The rings are
  pre-loaded at assembly using radial jacks to
  augment the wedge compression at the inboard
  faces of the TF coils and provide compression
  between the faces of the outboard intercoil
  structures during operation. The space available
  is very limited. Three jack concepts have been
  identified
• A mechanical system (proposed for IGNITOR)
  consisting of opposing wedges
• Stainless steel bladders with hydraulic fluid
• Commercial Enerpac jacks
• RD Task Select one primary concept plus one
  back-up. Mock-up and test under expected
  operating conditions simulating assembly,
  cooldown, operational pressures, and temperatures.

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Vacuum Vessel
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9.Remote Handling RD   Background Remote
handling of components is a key issue because of
activation. Verification of designs and component
maintenance tasks should be completed prior to
final design completion, or at least prior to
fabrication of components. The goal is to reduce
cost and times for replacement, repair and
maintenance tasks.   RD tasks 1.   In-vessel
transporter (articulated boom) component
handling end effectors 2.   In-vessel inspection
systems (laser metrology and video systems and
deployment mechanisms) 3.   Midplane and
auxiliary port handling vehicles and dexterous
manipulator 4.   YAG laser based divertor pipe
port lip seal cutting, welding, and inspection
tools, and power fastener wrench 5.   Midplane
port cask and air cushion transport vehicle 6.  
Hot cell remote repair stations fixtures for
midplane port assembly, divertor modules, and
cryopump  
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Vacuum Vessel Remote Handling RD
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Vacuum Vessel Remote Maintenance RD
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9.Fueling and Pumping   Background A new, twin
screw, extruder concept has the potential to run
steady state with reduced hydrogen ice
inventories compared to existing linear piston
extruders. In parallel, a cooling concept based
on a Gifford-McMahon cryocooler could be
developed to simplify operation of the pellet
injector by removing the need for liquid helium.
  The design of cryopumps for the divertor
relies on helium compression in the pump entrance
region to allow a compact, in-vessel
system.   RD Tasks Design, build and test a
prototype twin screw extruder with the goal of
minimizing tritium inventory for safety and
siting flexibility. Demonstrate extruder cooling
without LHe by using a G-M cryocooler. Design,
build and test a single cryopump module to
validate the expected inlet He compression which
permits a compact in-vessel pumping system.
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ICRH Antenna Mockup RD Background
Calculations for the two current strap antenna
show good performance, but the model requires
validation with an electrical mock-up of the
antenna. RD Task Build and test a mock-up
that uses a sheet metal antenna cavity current
straps, an uncooled Faraday shield, and is not
vacuum compatible. Measure electrical
characteristics at operating frequencies, refine
electrical models, and modify the design as
results indicate to improve performance.