1. SCH Controls Readiness Review – Cold Mass Iain Dixon November 4, 2015

2. Overview Cold mass design description Structural design criteria, metallic components – Stress summary – CICC quality controls Structural design criteria, insulation components – Major electrical quality control measurements Manufacturing procedures Risk assessment & CreADo 2

3. Cold Mass Design 3 Cold Mass: Winding pack and components associated with the coil at 4 K Major components – CICC Coil – Insulation – Magnet frame – Lead anchor and splice ties – Lead supports – Terminal and splice joints – Plumbing circuit – Voltage isolators

4. Structural Design Criteria, Metallic Components The structural design criteria is adopted from the Fusion Ignition Research Experiment (FIRE) Static – The design limits are a function of the material’s yield or ultimate strength, S m S m = the lesser of 2 / 3  y or ( 1 / 3  u, welded, 1 / 2  u, non-welded) – Usage factor For normal conditions (full field, power supply trips), k = 1.0 For anticipated conditions (quench), k = 1.1 For unlikely conditions (insert shorts), k = 1.2 For extremely unlikely conditions, k = 1.35 Fatigue – The stress condition is compared to SN curves A safety factor of 2 on stress and 20 on lifetime is applied – FCGR is used to determine the minimum detectable flaw size 4 Stress Category Stress Intensity Limits General primary membranek S m Local primary membrane1.5 k S m Primary Membrane (general or local) plus bending1.5 k S m Primary plus secondary3 S m

5. Static Stress Summary Ratio of Maximum Stress to Design Stress Intensity for Metallic Components 5 Operating ConditionMembrane Membrane + Bending Primary + Secondary Normal, Static0.960.640.35 Quench0.950.740.41 Fault0.830.870.54 Loss of Vacuum0.870.580.32

6. Fatigue Stress Summary Fatigue Test Results at 4.2 K of Welds in Comparison to Base and 45 T Hybrid 316LN (mod.) 6

7. Fatigue Stress Summary Using Linear Elastic Fracture Mechanics an allowable flaw size is set based on the lifetime of the component From the Paris Law, a majority of the crack propagation behaves in a linear manner on a log-log plot and can be described as da/dn = C  K m 7 With an initial flaw size of a, it will take n cycles to propagate a crack through the conduit wall An important requirement dictated by the FIRE Code is that one must detect a flaw size half of the initial (or allowable) flaw size. This detectable flaw size is the minimum requirement for the x-ray inspection that will be performed. For the SCH the allowable flaw size is a = 0.206 mm. This results in a minimum detectable flaw size of 0.10 mm.

8. CICC Quality Controls - Conduit Fabricated by Salzgitter-Mannesmann Stainless Tubes (SMST) Quality Control Parameters – Tube Length – Dimensions – Chemistry – Mechanical Properties – Porosity and Inclusions – Grain Size – Precipitate Carbides – Surface Finish The vendor and NHMFL conducted the quality control measurements NHMFL contracted out three independent companies for verification measurements of the chemistry 8 MF Conduit at SMST During QC Checks

9. CICC Quality Controls - Jacketing Jacketing performed at Criotec Impianti, Italy For each tube size, an optimal weld schedule was developed with the objective of high ductility and fatigue strength at low temperature and after aging in a similar style as the superconductor heat treatment. Weld qualification tests consisted of physical property measurements at 4.2 K of aged samples measuring ultimate and yield strengths, fatigue life Three inspections were performed after welding of each conduit 1.A plug with a diameter 0.2 mm less than the average tube inner diameter was passed across the weld region to check for potential obstructions with the cable during insertion. 2.A visual inspection outside and inside using a high resolution borescope were made. 3.Digital x-ray images were taken for detection of small internal and surface flaws (0.08 mm resolution). All welding/inspection was monitored by FSU or HZB personnel A weld rejection level of 14% was obtained A helium leak check on the fabricated CICC was performed on each piece-length 9

10. CICC Quality Controls & Inspection Borescope Images of Welds with Full and Lack of Penetration 10 Weld and x-ray stations (above) and example image (below)

11. Structural Design Criteria, Insulating Components Compressive stress < 2 / 3 ultimate strength at temperature At the interface of the conduit and insulation – no primary tensile strain is allowed – secondary strain < 1 / 5 of the ultimate tensile strain In-plane tensile strain < ±0.5% The shear / compressive stress at the interface between the conduit and insulation < 2/3 of the shear/compression limit curve Evaluation is performed on the insulation for each conductor turn 11

12. Structural Design Criteria, Insulating Components 12 Operating Condition Compressive Stress Compressive/ Shear Stress Primary Tensile Strain Secondary Tensile Strain In-plane Strain Normal, Static0.140.48None 0.37 Quench0.130.49None 0.36 Fault0.370.60None0.01 Ratio of Maximum Stress or Strain to Design Limit for Insulating Components

13. Major Electrical QC Measurements Impedance Spectrum – Performed after winding each layer – After heat treatment – After VPI – After surge test Paschen Test – Tests the ground plane insulation – Coil with voltage isolators attached, 4.0 kV – Fully assembled coil in cryostat, 3.5 kV Surge Test – Checks for internal shorts/weak insulation – Performed after VPI – 3 kV pulse across leads 13

14. Major Electrical QC Measurements Impedance Spectrum – Performed after winding each layer – After heat treatment – After VPI – After surge test Paschen Test – Tests the ground plane insulation – Coil with voltage isolators attached, 4.0 kV – Fully assembled coil in cryostat, 3.5 kV Surge Test – Checks for internal shorts/weak insulation – Performed after VPI – 3 kV pulse across leads 14 Final resistances of 0.8 G  at 2.5 kV and 0.5 G  at 4 kV were achieved

15. Major Electrical QC Measurements Impedance Spectrum – Performed after winding each layer – After heat treatment – After VPI – After surge test Paschen Test – Tests the ground plane insulation – Coil with voltage isolators attached, 4.0 kV – Fully assembled coil in cryostat, 3.5 kV Surge Test – Checks for internal shorts/weak insulation – Performed after VPI – 3 kV pulse across leads 15

16. Voltage Isolator Requirements, QC’s Requirements – Voltage: 3 kV – Pressure: 15 bar (room temperature) 18 bar (4 K) QC Measurements – Performed on all components Five thermal cycles Pressure tests: 22 bar @ 77 K, 15 bar @ RT Cold and warm leak tests Voltage isolators welded to test rig

17. Manufacturing Procedures Travelers and work procedures are used in most of the fabrication tasks Travelers include sign-offs and required inspections Work procedures are continually updated for quality improvement 17

18. Manufacturing Procedures 18

19. Risk Assessment, Equipment 19 Equipment EventLikelihoodConsequenceRisk CICC FailureVery UnlikelySevereMedium QuenchPossibleMinorLow Med Unprotected Quench, Low Energy PossibleMinorLow Med Unprotected Quench, High Energy Very UnlikelySevereMedium Plumbing/Isolator RuptureUnlikelySignificantMedium Short to CryostatVery UnlikelySevereMedium Offset from Insert ShortPossibleMinorLow Med

20. Risk Assessment, Personnel 20 PersonnelHazardsPresent Controls EventLikelihoodConsequenceRisk CICC FailureVery UnlikelyNegligibleLowHigh voltage, cryogens Engineering design, contained in cryostat, venting, restricted access, electrical isolation QuenchPossibleNegligibleLowHigh voltage, cryogensVenting, restriced access, isolation, quench protection Unprotected Quench, Low Energy PossibleNegligibleLowModerate voltageRestricted access, electrical isolation Unprotected Quench, High Energy Very UnlikelyNegligibleLowHigh voltage, cryogensRestricted access, electrical isolation, venting Plumbing/Isolator RuptureUnlikelyNegligibleLowCryogens Cryostat containment, venting, verification tests of every isolator Short to CryostatVery UnlikelyNegligibleLowHigh voltage Restricted access, electrical isolation, Paschen testing, grounding Offset from Insert ShortPossibleNegligibleLowLarge forcesDesign criteria, contained in cryostat

21. CrEADo CONDITIONSIGNAL INTER LOCK WARN OPERATOR CONTROL, Can be aborted Pause Slow Ramp Down, 50 A/s "FAST RAMP TO ZERO", 20 S Ramp Down INHIBIT GATING 10 Second Rampdown (when Breakers Open) OPEN BREAKERS 2 Seconds MONITOR Outsert Quench Voltage Taps differ from neighbors, >100 mV for 100 ms MPS Outsert Quench - 2 Co-Wound Coil shows difference to magnet voltage > 200 mV for 100 ms MPS Joint Quench Joint voltage > 20 mV for 50 ms MPS SC bus quenchV > 20 mV for 50 ms MPS

22. Thank You! dixon@magnet.fsu.edu