sch controls readiness review- cryostat nov 4-5, 2015 kurt cantrell
TRANSCRIPT
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!