FIRE Vacuum Vessel FY 03 Status and Plans

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FIRE Vacuum VesselFY 03 Status and Plans

• B. Nelson
• FIRE project meeting
• November 7, 2002
• PPPL

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(No Transcript)
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Presentation outline

• Status of vacuum vessel task area
• Geometry
• Design concept and features
• Analysis to date
• FY03 Plans
• Address open technical issues using the 2 m
  design
• Develop / define requirements and model VV for
  2.14 m geometry
• Prepare for PVR

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FIRE vacuum vessel
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VV parameters 2.14 m (2 m) design

• Configuration Double wall torus
• Shielding water steel with 60 packing
  factor
• Volume of torus interior 53 m3 (was 35)
• Surface Area of torus interior 112 m2 (was 89)
• Facesheet thickness 15 mm
• Rib thickness 15 - 30 mm
• Weight of structure, incl ports 65 tonnes (was
  50)
• Weight of torus shielding 100 tonnes (was 80)
• Coolant
• Normal Operation Water, lt 100C, lt 1 Mpa
• Bake-out Water 150C, lt 1 Mpa
• Materials
• Torus, ports and structure 316LN ss
• Shielding 304L ss (tentative)

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Active and passive stabilizing sys.

• passive plates 25 mm thick copper with integral
  cooling

RWM coils?
Active control coils, segmented into octants
IB and OB passive stabilizing conductor
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VV octant subassy w/passive structure
Outboard passive conductor
Inboard passive cond.
Vessel octant prior to welding outer skin between
ribs
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Passive conductor is also heat sink

• Copper layer required to prevent large
  temperature gradients in VV due to nuclear
  heating, PFCs
• Passive plates are required in most locations
  anyway
• PFCs are conduction cooled to copper layer
• Reduces gradient in stainless skin
• Extends pulse length

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Vessel analysis to date

• Vessel subjected to numerous loading conditions
• Normal operation (gravity, coolant pressure,
  thermal loads, etc.)
• Disruption (including induced and conductive
  (halo) loads
• Other loads (TF current ramp, seismic, etc.)
• Preliminary FEA analysis performed on 2.0 m
  geometry
• Linear, static stress analysis
• Linear, transient and static thermal analyses
• Main issues are disruption loads, thermal
  stresses

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Vacuum vessel mechanical loads
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TSC runs confirm induced currents will
concentrate in passive structures

• Several TSC disruption simulations prepared by C.
  Kessel
• Centered disruption induces 5 MA in passive
  plates (out of 6.5, now 7.7)

• VDE simulation used as basis for further analysis

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VDE analysis based on TSC runs

• TSC output used to create drivers for Eddycuff
  model of VV
• Peak loads applied to ANSYS model of VV
• Halo loads from TSC mapped directly onto VV model

Inner Face Sheet
Outer Face Sheet
Copper Plates
EDDYCUFF EM Model
ANSYS Structural Model
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Plasma Evolution (TSC)
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Current vs Time
Plasma Current
Induced Vessel Current
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Induced Eddy Currents at Time 302-ms (end of
plasma current quench)
Constant Current Vectors
Proportional Current Vectors
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EM Pressure due to Induced Tor. Current

• Max force -1.4-MN radial, 1.2-MN vertical per
  1/16 sector (19 MN tot)

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EM Forces due to Halo Current

• Mapped directly from TSC to ANSYS, Halo current
  16 Ip
• Max force -0.24-MN radial, 0.48-MN vert. per
  1/16 sector (8MN tot.)

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Divertor loads from current loop

• Loads based on PC-Opera analysis ref
  Driemeyer, Ulrickson

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Combined stress, with VDE

• Stresses due to gravity, coolant pressure,
  vacuum, VDE
• VDE load includes direct EM loads on vessel
  (induced current and halo) and non-halo divertor
  loads

Stress concentrations around div suport pins
(need reinforcement and finer FEA model)
1.5Sm 26 ksi (195 Mpa)
Stress is in psi
Stress gt 50 ksi is in gray color
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Nuclear htg and thermal effects

• Vacuum vessel is subject to two basic heat loads
• Direct nuclear heating from neutrons and gammas
• Heating by conduction from first wall tiles
  (which in turn are heated by direct nuclear
  heating and surface heat flux)
• A range of operating scenarios is possible, but
  the baseline case for analysis assumes
• 200 MW fusion power, 150 MW is current baseline
• 100 W/cm2 surface heat load on first wall, 45
  MW/cm2 is current baseline
• pulse length of 20 seconds
• Vessel is cooled by water
• Flowing in copper first wall cladding
• Flowing between walls of double wall structure

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Heat loads on vessel, at IB midplane

• Fusion power of 200 MW (baseline power is 150 MW)
• Surface heat flux is variable, but 100 W/cm2 is
  assumed

Volumetric Nuclear Heating, IB
midplane Location (W/cm3) A - Be FW 33.3 B
- Cu FW 46.9 C VV 33.8 D VV
30.3 ref M. Sawan
B
C
D
A
Cu cladding
Double wall VV
Tile
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2-D temp distr after 20 sec pulse

• Inboard midplane Outboard midplane

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Nuclear heating distribution
Neutron wall loading Volumetric heating
plasma side coil side divertor

• Ref M. Sawan

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3-D temp distr in VV after 20 s
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VV thermal deformation and stress
Peak

• Stress
• (High stress region very localized)

Deformation (Max 3 mm)
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Combined stresses, 20 s pulse

• Nuclear heating, gravity, coolant pressure, vacuum

• Only very local regions exceed 3Sm (390 Mpa or
  52 ksi)

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Combined stresses, 20 s pulse, with VDE

• Nuclear heating, gravity, coolant pressure,
  vacuum, VDE

Only facesheets and Cu are plotted
Stress is in psi
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Conclusions of analysis so far

• Have disruption loads been analyzed? YES
• but additional load cases must be run using
  updated geometry
• Does Vacuum Vessel limit pulse length? ITS CLOSE
• 20 second pulse should be achieveable
• Thicker tiles, external heaters are options to be
  explored for more margin
• What would logically be next?
• Optimized geometry and refined FEA models
• Revised load cases, including lower fusion power,
  lower surface heat flux, higher plasma current
• Dynamic analysis
• Fatigue analysis, including plastic effects

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Task 1 Address open technical issues

• Scale existing thermal and thermal stress
  analysis of vessel for revised fusion power and
  pulse length combinations (2-D, approx. 3-D
  calc.)
• Run new thermal stress analysis with preheated
  outboard wall, thicker tiles on outboard
• Perform self-consistent EM calculations for new
  disruption cases (Dennis Strickler has run some
  cases)
• Integrate FW tiles / magnetic loops with VV
• Schedule Now through June
• Resources TBD, but budget 2 man months

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Task 1b Technical issues outside budget

• Develop, in conjunction with RH and PFC groups,
  the basic divertor and FW attachment schemes
  consistent with loads and RH requirements
• Perform integrated structural analysis of vacuum
  vessel for disruption load conditions, including
  divertors, tiles, and port mounted equipment
• Develop, in conjunction with RH, the basic
  concepts for structural and vacuum interfaces
  between the port plugs and the vessel
• Re-evaluate vessel supports
• Develop basic plumbing schematic for cooling
  water, leak checking
• Schedule TBD
• Resources TBD

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Task 2 Requirements definition

• New Geometry
• What is the radial and vertical build?
• What is space needed for RWM coils?
• How much do we tweak VV geometry to solve stress
  issues?
• Operating basis, including fusion power, pulse
  length, plasma current, field
• What will be the baseline operating space?
• Ports for diagnostic access, especially any
  tangential viewing requirements
• Ken Young is developing this
• Diagnostic magnetic loops / coils
• Ken Young is defining these, and they may have
  significant design impact due to large number and
  type (50 toroidal loops, 10 saddle coils, BR/BZ
  coils, 2 arrays of 70 each, toroidal and poloidal
  arrays of Mirnov coils and some number of
  diagnostic sockets)
• Schedule Now through April?
• Resources TBD, but ltlt 1 man months budget
  available

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Vessel shell dimensions to tweak
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Task 3 Prepare for PVR

• Summarize baseline design and analysis
• Re-model VV??
• Attend PVR (?)
• Schedule July, primarily
• Resources TBD, budget lt 1 man months

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Summary

• Draft task list for FY-03 has been developed
• Technical issues to be addressed include
• Combined disruption / thermal stress estimates
  and thermal stress limit on pulse length
• Look at potential fixes for thermal stress
  problem
• Magnetic diagnostic integration
• Technical issues to be defered include
• in-vessel component attachments and integrated
  analysis
• Port plug integration
• Requirements definition is key task for migration
  to 2.14 m size
• Geometry sizes, thicknesses, for stress
  problems, RWM coils
• Baseline performance envelope
• Diagnostic access, especially magnetic
  diagnostics (do we need more space inboard?)
• Preparation for PVR is primary milestone for
  FY-03

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Preliminary VV stress summary
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Additional backup slides
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Vacuum vessel design issues

• Thermal stresses vs pulse length
• Disruptions
• Load definition
• Divertor supports
• Vessel supports
• Passive stabilizing conductor integration / fab
• Concepts are being developed for
• Divertor interface
• Vertical and lateral supports

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Vessel octant subassembly fab. (3)

• Octant-to-octant splice joint requires double
  wall weld
• All welding done from plasma side of vessel
• Splice plates used on plasma side only to take up
  tolerance and provide clearance
• Plasma side splice plate wide enough to
  accommodate welding the coil side joint

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Vessel port configuration
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Vessel port details
Auxiliary port Port dimensions 0.47 x .104 x
.180 m Cross sectional area of port .067 m2
Midplane port Port dimensions 0.71 x 0.63 x
1.25 m Cross sectional area of port .8 m2
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Vessel inboard shell fabrication
Weld the formed extrusions together

• Machine surfaces of steel weldment,
• Fab copper by gun drilling/machining or use a
  sandwich structure
• Attach manifolds to copper

Diffusion bond the formed copper assembly to the
steel assembly
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Vessel outboard shell fabrication
Diffusion bond copper to inner face sheet
Join two ½ sections to form one octant

• Weld ribs and port stubs to inner skin
• Add conduit for active control coils

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Vessel upper and lower shell fab.
Form and trim inner skin

• Weld ribs to inner skin
• Add port reinforcing stubs

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Vessel octant subassembly fab.
Weld inner skins and ribs of inboard, outboard,
top and bottom sections together
Add shielding subassemblies between ribs
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Vessel octant subassembly fab. (2)
Add outer skin on / between ribs
Completed octant ready for assembly
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VV analysis, ANSYS FEA model

• Model prepared by HM Fan
• 64 poloidal ribs inboard, 64 poloidal ribs
  outboard
• thickness of elements assumed as
• 15 mm for vessel facesheets,
• 30 mm for port at midplane,
• 15 mm for port above/below midplane,
• 15 mm for most poloidal ribs,
• 30 mm for OB ribs at supports
• 25 mm for copper stabilizers

Ref H.M. Fan
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Heat loads on vessel, at midplane

• Fusion power of 200 MW
• Surface heat flux is variable, but 100 W/cm2 is
  assumed

Volumetric Nuclear Heating, IB
midplane Location (W/cm3) A - Be FW 33.3 B
- Cu FW 46.9 C VV 33.8 D VV
30.3 ref M. Sawan
B
C
D
A
Cu cladding
Double wall VV
Tile
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Nuclear heating distribution
Neutron wall loading Volumetric heating
plasma side coil side divertor

• Ref M. Sawan

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2-D temp distr after 20 sec pulse

• Inboard midplane Outboard midplane

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VV thermal stress in skin and ribs

• skin ribs