FDR - NCSX Central Solenoid Support Structure Fred Dahlgren Joe Rushinski 6 Sept 2006.

FDR - NCSX Central Solenoid Support Structure

Fred Dahlgren

Joe Rushinski

6 Sept 2006

FDR - Central Solenoid Support Structure - 9/6/06

Charge:

Does the coil structure provide adequate support for the PF1a coils with sufficient margins of safety?

Have the interfaces with other sub-systems been defined and are they compatible?

Are the drawings and supporting documents complete and ready for sign-off?

Has the analysis been documented and checked?

Are the cost, procurement and assembly schedule consistent with the program schedule and budget?

Design Description:

•The structure consists of solution annealed 304L stainless weldments fabricated mainly from 1/4”, 3/8”, 1/2” and 3/4” thick plate (µ < 1.02).

•The individual structural segments are 120 degrees with G-11CR insulating plates, bushings, and washers between the adjacent segments.

•A mid-plane sub-assembly will space the top & bottom PF1A coils (re-claimed from NSTX), at ± 40 cm from the mid-plane.

•The top and bottom sub-assemblies will have six 3/4” tie rods with nuts and belleville washers and will provide a 12,000 lb. axial pre-load clamping force on the two PF1A coils. The bellevilles’ will accommodate up to 0.015” of differential thermal contraction/expansion (~ 0.007” amount required).

•Twelve radial support arms (6-top & 6-bottom) will attach the solenoid structure to the main coil structure.

•All bolting materials (nuts, bolts, washers, etc.) will be 316 stainless.



PF1a Coil Modification: Water fittings & tubes must be re-worked & re-insulated

Coil Description: 48 turn double layer spiral wound, 0.787” square CDA107 drawn Cu conductor with 0.354 dia. coolant hole. Insulation: 0.026” thk. CTD112P w/0.0065” Kapton-1/2-lapped (0.052” turn to turn) & 0.054” thk. ground wrap.

Coil Dimensions:

12.8” I.D.

16.26” O.D.

21.08” axial length

48 turns

Cu area: 0.52 sq.in.

Hole dia.: 0.354”

Leads: 12.6” & 16.9”

Fabr. Details see:

NSTX-SPEC-13-041


PF1a Coil/Structure Assembly - Pre-assembled


111.5”


Assembly will have ~55” clearance for lift

Materials:

304L solution annealed plates

ER316LN weld filler

316L nuts, bolts, washers, & rods

G10/11CR insulating plates @ 120 deg.

G10/11CR washers & bushings

Copper tubing

Brass Swagelok (B-600 series) tube fittingsInterfaces:

Cryogen cooling lines connect to top & bottom LN2 feed/return lines. Pressure & flow requirements defined, connecting lines (with insulating breaks) to cryogen supply & return plenums are needed. Four thermocouples are required to monitor coil inlet/outlet.

Bus pads at the top & bottom locations are defined. Bus connection to power supply are needed. Bus interface defined, scenario A.1.3.4 defines the current & voltage requirements.

Top & bottom mounting pads bolt to same threaded holes to be used for permanent solenoid supports. Loading @ support interface defined.


*

* From Allegheny Ludlum Technical Data Blue Sheet

2/3rd Yield allowable @80K = 46.6ksi

304L Properties*

* From Allegheny Ludlum Technical Data Blue Sheet


Cooling analysis:

Cooling Analysis Shows < 1 deg.K rise per pulse & no ratcheting

Plot of the PF1a exit temperature vs. time

DP = 10 psi

Qdot = 1.14 GPM

AMPS = 19.3 kA

ESW = 0.16 sec.

Rep.Rate = 900 sec.

0.787

Ø 0.354


FEA Model of PF1A & Supporting Structure:

• A 1/6th-Upper half Nastran linear FEA model was used.

• PF1A coil modeled as discrete turns with insulating layers (CHEXA & CPENTA).

• Structural components modeled with plate elements (CQUAD4 & CTRIA3).

• Tie rods modeled with solid elements (CHEXA & CPENTA).

• Bolts modeled with CBAR elements attaching plates & adjacent weldments.

• EM loads on PF1A determined from dforce7b (Biot-Savart - U.C. code).

• Symmetry boundary conditions were applied (toroidal, vertical and rotational).

• Coil top & bottom surfaces not permitted to slide radially (rel. to supports).

• Model Summary:

Number of GRID Points = 21979 Number of CBAR Element = 57 Number of CHEXA Elements = 13232 Number of CPENTA Elements = 1696 Number of CQUAD4 Elements = 2287 Number of CTRIA3 Elements = 170

• Loading Conditions considered:

Gravity, EM, Thermal, Seismic


3/4” Tie Rod / belleville washer, and bolted connection modeled


PF1A Coil Model: CPENTA & CHEXA isotropic Cu & Epoxy Glass


Loads considered:

Gravity Loads with 1g & 2g vertical downward, B.C.: Symmetry & fixed at the upper bracket bolts (attached to the inner segmented ring castings which are assumed rigid).

Horizontal seismic loading using static 0.15g acceleration per the NCSX/IBC2000 criteria (h~15ft, Fp=0.108 x 1.369 = 0.147 ~ 0.15g).B.C.: Symmetry & fixed @ upper bracket bolts.

Thermally induced stress from cool down and temperature differentials using mean CTEs from R.T. to 77 oK. B.C.: Symmetry & fixed @ upper bracket bolts. (CTE-Cu from NIST data, CTE-304L from ITER data)

Electro-magnetic loading for coil day-1 scenario A.1.3.2: Ipf1a = 19,299 A & 23,500 A (simulates M.C. loading)Ipf4 = 3,141 AIpf6 = 241 AIpl = -26,068 A & 0.0 A(Ipl = 0.0 was highest loading)

B.C.: Symmetry & fixed @ upper bracket bolts.

Vertical Displacements for a 1-g gravity: Max = 0.0025”



Peak Tresca stress - 1-g loading: 3.44 ksi @ mtg. bolt holes

Peak Tresca Stress: 3.44ksi


Vertical Displacements for (fault) 2g loading condition: -.005” max.


Tresca Z2 stress for a 2g loading condition (ie. if bottom supports loose or removed) Max Stress: 7ksi @ the mounting bolt holes

Lateral 0.15g seismic displ. 0.002” at the middle of the tierod

Peak Tresca stress 2 ksi @ the bolt hole

Seismic (static) load 0.15g horizontal acceleration with top mtg. bracket fixed

Peak Tresca Stress 2.0ksi



Thermal Loading: Coil @ 80K & Structure @ R.T.(extreme case)

Max Vertical displacement: -0.085” @ the top of the coil


Need to avoid extreme thermal differentials during cooldown

Peak Tresca Stress 78.6 ksi >> yield stress & allowable


A more realistic thermal loading assumes a temperature difference of 30 K and yields a relative vertical displacement of -0.012”. The differential rod & bellville to top plate shows about 0.005” - just over 50% of it’s linear range.

∂y ~0.005”

∂y (tot.): -0.0115”


Peak Tresca stress for a 30 K temperature differential: 15.6 ksi

Peak Tresca: 15.6 ksi


Tresca Peak Stress is 4.6 ksi in coil insulation for 30 oK temperature differential

Baseline EM Loads assumed the 0.5T 1st Plasma Scenario

Coil EM Loading

No Plasma:

Fr = 4,369 lbs/in [5,660 lbs/in*]

Fz = -3,722 lbs (total) [-6,355 lbs*]

DFORCE7b result:

Hoop Stress(avg.)=1.27ksi [1.84ksi*]

Net Stress = 1.54ksi

With Ipl = -26,068 amps

Fr = 4,318 lbs/in

Fz = -3,647 lbs (total)

DFORCE7b result:

Hoop Stress (avg.)=1.25ksi

Net Stress = 1.53ksi

*For Ipf1a = 23,500 Amps



EM Loading was calculated as J x B body forces at each coil turn.

Genforce subroutine added to DFORCE7b to generate Nastran Force input.

Equivalent discrete forces for the worst cases were applied at each of 6 interior element grid points. Centroidal currents (@ each turn) were assumed. The loading from the M.C. field was simulated by running a 23.5 kA PF1a current case, which duplicates the peak vertical loading from the M.C. radial fields.


Typical EM grid point load resultants @ 6 interior points in conductor


Coil Displacements (SRSS) From 19.3kA EM Loads - No Axial Pre-load

No Plasma -Maximum displacement was 0.0005” at the coil mid-plane

Peak Displ. 0.0005”


Peak Tresca stress in the coil from 19.3kA EM loading only: 1.83 ksi

Peak Tresca: 1.83ksi

Peak Tresca Stress in supports 19.3kA EM + Thermal (cool-down): 14.0 ksi

(with CONROD elements at bolt hole perimeter)



Peak Tresca Stress in supports 19.3kA EM + Thermal (cool-down): 2.51 ksi

(with MPCs replacing CONROD elements at bolt hole perimeter)


Peak Tresca Stress in Coil for 23.5 kA EM-only loading, 2.78 ksi (Loading includes the effects of the M.C. peak fields)

Peak Tresca Stress in Cu 2.78 ksi


Peak Tresca Stress in Support for 23.5 kA EM loading, 3.68 ksi


Peak Tresca Stress in coil insul. for 23.5 kA EM-Cold loading, 3.17 ksi, 2.9 ksi in Cu

Peak Tresca Stress: 3.17 ksi Peak Cu Tresca Stress: ~2.9 ksi


Displacements for combined gravity, thermal, EM loading

Peak Displ. 0.167” (SRSS)


Tresca stress in coil from combined gravity, thermal, and EM loading

Peak Tresca Stress = 3.16 ksi - insulation

Average coil Tresca stress ~2-3ksi


Peak Tresca Stress 2.68 ksi

Peak Stress in supports from combined gravity, thermal, and EM load

*Allowable 304L @ 80 oK = 46.6 ksi (321 MPa) (2/3rd yield criteria)

Allowable CDA107(10%CW) Cu @ 80 oK = 16 ksi (110.6 MPa) (2/3rd yield criteria) **

Allowable CTD112P-w/Kapton @ 80 oK = 8.86 ksi (61.3 Mpa 2/3rd ultimate criteria) -per ITER test data

§ Actual margins on max shear are double these values

(C2 = 0.6, Sc= 0.0 - Eqn. From NCSX design criteria, 5.6 ksi no compr.)

**Sy = 124 - 0.241xT +14.1xCW - 0.166xCW2 = 230.5MPa, 2 x sigma = 64 MPa,

230 - 64 = 166, 2/3 x 166 = 110.6 MPa (16 ksi)

(From NIST Monograph 177 -Simon, Drexler, Reed)


Load case Max. Displ. (inch -SRSS)

Suppt. Coil

Max Tresca Stress -ksi

Suppt. Coil

Location

Suppt. Coil

Margin on Allowable*

Suppt. Coil

Gravity-1g

Seismic

0.0025 v 0.0025 v

0.002 h < 0.0002 h

3.44 negl.

2.0 negl.

mtg.brkt __

Rods __

13.5 __

23.3 __

Thermal (∂30 oK)

0.0112 0.005 15.6 3.3 Cu

4.6 (ins.)

@bolts corners 3.0 4.84

1.9/1.2§

EM (23.5kA) 0.0005 0.0005 3.68 1.83 @bolts mid-coil 12.6 12.3/8.7

EM + 1g

+ cooldown

0.167 0.0695

(SRSS) (SRSS)

2.68 2.9-Cu

3.16-ins.

@bolts mid-coil

outer c.

17.4 5.5

2.8

Stress Analysis Summary

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Coil Testing Requirements:

Electrical

After re-configuring and re-insulation of coolant tubes, coils will require a hi-pot to ground at 2 kV (2 x Vop. +1000) and a megger at room temperature and 80 deg.K.

Insulating breaks between field periods will be meggered @ 2kV

Mechanical

During cool-down for 80 deg.K electrical test, a flow measurement for a delta-P of 10psi will be required.

Thermocouples on inlet and outlet tubes will be needed to provide a record of T vs. time for the cool-down.



Cost & schedule:

•Build in-house preliminary est: ~75k$

•Will issue an RFQ for 304L & 316L by late Sept.’06

•Anticipate a 4-6mo. Delivery

•A 316L material may delay things a month or two and may cost

30% more.


Conclusions:

Charge:

Does the coil structure provide adequate support for the PF1a coils with sufficient margins of safety?

A: Stress margins on allowables for both coil and support exceed project & code requirements.

Have the interfaces with other sub-systems been defined and are they compatible?

A: Interfaces to machine structure, cryo-system, and electrical power defined & compatible.

Are the drawings and supporting documents complete and ready for sign-off?

A: Drawings & BOM are complete and ready for checking/sign-off.

Has the analysis been documented and checked?

A: The stress & thermal analysis have been documented & are being checked.

Are the cost, procurement and assembly schedule consistent with the program schedule and budget?

A: Cost & schedule are consistent with project schedule and, pending responses from RFQ,

should fall within the current project budget.


PF1a Radial Running Load

855000

860000

865000

870000

875000

880000

885000

890000

895000

900000

905000

0 60 120 180 240 300 360

Angle, deg

Running Load, N/m

PF1a OnlyPF1a + PF4&6

PF1a,4,6 & Mod

per A.Brooks 9/1/06

PF1a Vertical Running Load

-30000

-25000

-20000

-15000

-10000

-5000

0

0 60 120 180 240 300 360

Angle, deg

Running Load, N/m

PF1a OnlyPF1a + PF4&6

PF1a,4,6 & Mod

per A.Brooks 9/1/06



Fatigue analysis:

304L Peak Tresca Stress: 15.6 ksi (EM + 1g + 30 oK delta)

Operating stress belowthe /2 @ 130,000 cycles

The 2/20 project criteria for fatigue is satisfied although the anticipated usage of the PF1a coils and supports is significantly less than the 130,000 cycles.

20x life

15

Shear Strength CTD112P (w/Kapton) 13.3 ksi @77 deg.K


ITER shear-compression tests

Max Shear: 6.78 ksi for 15 degree angle(12ksi compr.) @ 77 deg. K


6.7 ksi

40 MPa, 5.8 ksi-static & fatigue


Inner radial stop will maintain central alignment of PF1a coils

FDR - NCSX Central Solenoid Support Structure Fred Dahlgren Joe Rushinski 6 Sept 2006.

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