SCH Controls Readiness Review-Cryostat

Nov 4-5, 2015Kurt Cantrell

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Overview

• Cryostat Overview• Quality Control - Manufacturing Procedures• Quality Control - Testing• Cryostat Design• Structural Design Requirements• Risk Assessment

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Cryostat OverviewCryostat Performance Goals:• Provide vacuum insulation for

the outsert coil• Provide radiation barrier for the

outsert coil• Provide for cryogen services,

instrumentation and power feedthrus for the outsert coil

• Support cold mass weight• Support coil misalignment loads• Support fault forces• Provide for interface with

outsert coil, housing and hydrant

Structural Design Criterion• ASME PVC Section VIII, div. 2• ASME B31

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Cryostat- Manufacturing Procedures

• Cryostat was fabricated at Criotec Impianti in Chivasso, Italy (not a holder of ASME PVC stamp)

• Fabricated to NHMFL drawings which were designed to the ASME B&PVC section VIII, div. 2 and ASME B31

• Communication• Videoconference every two weeks• Frequent email traffic• Personnel were present to check for manufacturing issues and during assembly fit-up• Personnel were present during important test stages

• Drawing review• Various drawing revisions were made by Criotec

• Change to metric material thickness or other European standards• Minor material property changes• Facilitate manufacturing to how they are accustomed• Thermal bore tube shield design to follow the style implemented for the HZB cryostat

• Tracking Engineering Changes• A drawing tracking form is filled out to track changes• A change to the revision number is made in the drawing block• A model is sent to NHMFL for approval

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Cryostat- Manufacturing ProceduresExample of Engineering Tracking Form

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Cryostat-Quality Control -TestingAssembly Description Test Description Location

Major structural parts NDE of welds Criotec ImpiantiVacuum Vessel Helium leak check at room temperature to 3E-9 mbar-l/s Criotec Impianti

Warm Bore Tube Hydrostatic pressure test to 67.5 barg (1.3x MAWP) Criotec Impianti

LN2 Shields Plumbing and Bore Tube Shield

Hydrostatic pressure to 7.5 barg (1.3x MAWP) Criotec Impianti

LN2 Shields Plumbing and Bore Tube Shield

Helium leak check at 77 K to 3E-9 mbar-l/s Criotec Impianti

SHe and LN2 Services Three thermal cycles Criotec ImpiantiSHe Services Hydrostatic pressure to 27 barg (1.3x MAWP) Criotec Impianti

LN2 Shields Supply/Return (and associated plumbing)

Hydrostatic pressure to 7.5 barg (1.3x MAWP) Criotec Impianti

LN2 Tank (and associated plumbing) Hydrostatic pressure to 3 barg (1.3x MAWP) Criotec Impianti

SHe and LN2 Services Helium leak check at room temperature to 3E-9 mbar-l/s Criotec Impianti

Insert housing/hydrant Hydrostatic pressure test to 67.5 barg (1.3x MAWP) RV Industries

Completed SHe circuit Helium leak test by pumping on vacuum vessel while circuit under 150 psi NHMFL

Completed LN2 circuit Helium leak test at 15 psi differential NHMFL

Vacuum vessel Helium leak test NHMFL

Tests Performed Post Fabrication

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Cryostat Design-Vacuum Vessel

Requirements• High Vacuum Inside• Fault Load, Strongback• Service penetrations

Design• Welded/Bolted

Construction• Warm O-Ring Seals

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Cryostat-Mechanical Loads

Fault Load Path

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Cryostat Design-Bore Tube/Strongback

Requirements• Fault Load• Radial Stiffness for 40 Bar Over Pressure• Return water• Operation-30 bar water inside• High Vacuum Outside

Design• Double Wall• Machined Weldment/Forging• Axisymmetric

Water Supply

Water Return

Fault Load

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Cryostat Design-Bore Tube/Strongback FEA

• The SCH insert housing is a double wall structure containing coils inside, and supported by cryostat main frame structure

• Cooling water enters in the housing, passing through coils, and flows out in between the double walls• FEA model is extracted for cornerstone structures along the loading path

Structural load path

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Cryostat Design-Bore Tube/Strongback FEA Structural meshes

scale factor, 50

Boundary conditions

Rib and weld function in difference load scenarios

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Cryostat Design-Bore Tube/Strongback FEA: Deflection Example

1) During normal operation, the distance between double walls will shrink <0.01mm in the top and shrink <0.05mm in the bottom 2) Outer wall will move 0.0152mm toward inner wall in the top, and 0.044mm toward cryostat in the bottom3) Inner wall will move 0.0046mm toward outer wall in the top and 0.088mm toward outer wall in the bottom

Normal operation radial deflection 1) In current model, during normal operation the length of the outer wall shrink approximately 0.034mm as well as the outer wall will shrink 0.056mm (the compliance of the threaded ring and the cryostat are not considered)2) The offset between the D coil and the outsert is approximately 0.022mm.

Normal operation axial deflection

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Cryostat Design-Insert Hydrant FEA

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Cryostat Design-Cold Mass Support Columns

Requirements• Axial Stiffness Fault Load (Tension/Compression)• Minimum conduction load 300 K to 4 K

Design• 88 K Intercept• Integral Manifolds• Machined Weldment• 1.3 watts/Column to He• 7 watts/Column to N2

Buckling stability of the ColumnsTresca stress FEA detail

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Cryostat Design-Warm ColumnsRequirements

• React Vacuum Loads• Weight• System Ground

Design• Constant Cross-section• 88 k Shield• Bolted w/ adjustment• Machined Weldment

The vacuum load to the SCH structure is supported by cryostat OD wall, warm columns, and the bore tube. From FEA, the bore tube share 19% of the total vacuum load.

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Cryostat Design-Warm to Cold Links

Analysis-Linear stress/strain-Magnetic stiffness

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Cryostat Design-Permanent Frame(External consultant David H. Melvin, Inc.

analysis results)• Analyzed to conform to the AISC

design code by licensed State of Florida PE

• Loads considered:-Vertical load of ~ 220 kN-Side load of ~ 20 kN

Displacement (in)

Frame stress plot

• Known loads external:• Side loads:

• 5 kN: 10 mm offset from iron shield• Cooling water loads (load share with

plumbing)• 26.6 kN bus bar load

• Vertical loads:• System weight of 205 kN downward• 12 kN downward due to offset with

iron shield• 38 kN downward due to rebar in the

floor

Action options:-Re-analyze frame considering all loads-Proof test frame using known side loads

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Cryostat-Venting Safety

Protective barrier around HTS leads and cryogenic services/vents

6” pipe weight-loaded vent on vacuum vessel for loss of cryogen containment

GN2 vent line carries all GN2 outside

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Cryostat-Risk Assessment

Thank You!