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Cryogenics for LHC Test Benches Safety Aspects

Explore the safety aspects and operational insights of cryogenic systems in LHC test benches, discussing experience and key technical details.

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Cryogenics for LHC Test Benches Safety Aspects

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  1. Cryogenics for LHC Test Benches Safety Aspects Overview of the Test Station Overview of the Operation Safety matters: Experience Discussion CSOC Meeting 29 September 2004

  2. Overview of the Test Station • Block Diagram • General view • Cryogenic Feed Boxes • Cooldown/Warmup system CSOC Meeting 29 September 2004

  3. COMP 3 (2005) • COOLDOWN-WARMUP SYSTEM (CWS) • 2 x100g/s 2-12 bar GHe Compressors • LN2 distribution • 2 x 120 g/s 140 kW Cooldown Units • 1 LPGHe Heater 200 kW • 1 HPGHe Heater 30 kW COMP 1 COMP 2 HP GHe Heater 30 kW LP GHe Heater 200 kW CWU 2 C only CWU 1 C only Cooldown Warmup Line, 12 valve boxes (CWL) CFB CFB CFB CFB CFB CFB CFB CFB CFB CFB CFB CFB Cryogenic Compound Line, 12 valve boxes (CCL) WPU 1 CCU 1 (IHI) (2005) CCU2 Linde Heater 1 30 kW Other Utilities required for Magnet Tests GHe PUMPING SYSTEM Heater 2 30 kW WPU 2 GHe 40 bar GHe Recovery GHe GN2 LN2 LHe GHe <90 K GHe INTERFACES WITH CRYOGENIC FACILITIES OF ZONE 18 CSOC Meeting 29 September 2004

  4. CFBs CWU2 CCL CWU1 HEATER CWL SSS DIPOLE CSOC Meeting 29 September 2004

  5. D2FCV239 D2FCV269 D2FCV290 D1FCV239 D1FCV269 D1FCV290 E2FCV239 E2FCV269 E2FCV290 E1FCV239 E1FCV269 E1FCV290 F2FCV290 F1FCV239 F1FCV269 F1FCV290 F2FCV239 F2FCV269 D2FCV265 D1FCV265 E2FCV265 E1FCV265 F1FCV265 F2FCV265 F2FE F1FE E2FE E1FE D2FE D1FE 265 265 265 265 265 265 F2FE F1FE E2FE E1FE D2FE D1FE 239 239 239 239 239 239 02PDT 288 02FCV270D HV000 TE F270 02FCV257 02FV263D 02FE 02FT 270 288 254 HV000 PDT 230 CWU2 01PDT 288 01FCV270A HV000 01FCV257 01FV263A 01FE 01FT 288 254 HV000 CWU1 SV241 SV231 01PDT SV236 237 PDT HV231 HV241 240 SV243 HV236 TE TE 234 TE HV243 235 PCV232 233 HV000 LPGHe H2 TE 01FE 242 237 HV000 HPGHe H4 C2FE C1FE B2FE B1FE A2FE A1FE 239 239 239 239 239 239 C2FE C1FE B2FE B1FE A2FE A1FE 265 265 265 265 265 265 A1FCV265 C2FCV265 C1FCV265 A2FCV265 B2FCV265 B1FCV265 A2FCV269 A2FCV290 A1FCV239 A1FCV269 A1FCV290 C2FCV239 C2FCV269 C2FCV290 C1FCV239 C1FCV269 C1FCV290 B2FCV239 B2FCV269 B2FCV290 B1FCV239 B1FCV269 B1FCV290 A2FCV239 02TE 263 01TE 263 Cooldown / WarmUp System CSOC Meeting 29 September 2004

  6. CWS Specifications • Helium Circulation for Cooldown and Warmupup • Magnets are cooled down and warmed up with a forced circulation of GHe. • 2 x 100 g/s, 2/12 bar-compressors in SW18 (3 compressors in 2005) • Cooling Down to 90 K • LN2 supply line from the two 50 000 L dewars supplying two Cooldown Units so called CWU 1 and CWU 2 each including a LN2 vaporizers and a GHe counter flow heat exchanger • Maximum cooldown mass flow rate with both CWUs in parallel:220 g/s GHe @ 80 K using 1200 g/s LN2 • 85 g/s GHe @ 80 K are required for the cooling down of 1 magnet in 12 h • Warming Up to 300 K • Injection of preheated GHe @ 320 K and heating of the returned GHe • One 30 kW electrical heater: Max. flow rate: 190 g/s GHe @ 290 K • One 200 kW electrical heater: Max. flow rate: 175 g/s GHe @ 80K. • 90 g/s GHe @ 320 K are required for the warming up of 1 magnet in 12 h CSOC Meeting 29 September 2004

  7. Cryogenic Feed Box CSOC Meeting 29 September 2004

  8. Set of 4 x 0.6 kA Current Leads 2-position pair of13 kA Current Leads Heat Exchanger 2-positionSC lines M1/M3 2 x Retractable Sleeves M2, M1/M3 CRYOGENIC FEED BOX AIR LIQUIDE CSOC Meeting 29 September 2004

  9. Sealing of CFB-magnet interfaces CSOC Meeting 29 September 2004

  10. Cryomagnet / CFB Interfaces INFRASTRUCTURE Cryogenic and conventional Utilities CRYO-MAGNET in setup, cooldown, powering, quench, warmup phases. CRYOGENIC FEED BOX Conventional cryogenic system with passive final safety devices. Operation handledby a PLC-based control system. CSOC Meeting 29 September 2004

  11. No Cryomagnet / CFB Interfaces • INFRASTRUCTURE • 14 circuits connected to each CFB (Compressed Air, GHe, LHe, GN2, …), vacuum barriers • Pressures from 0 to 14 bar, Temperatures from 4.5 to 320 K. CRYOGENIC FEED BOX 7 accessible CFB hydraulic interfaces for cryo-magnet (isolation valves closed) The CFB control system handles and monitors this sequence. CSOC Meeting 29 September 2004

  12. PT CFB -Magnet (de)connection CFB circuits are locked and monitored by CFB PLC and locked by operators. Magnet side Utilities Circuits locked by CFB PLC Utilities side GHe 4.5 K, 16 mbar X PT GHe 80 K, 14 bar N ALARM GHe 320 K, 14 bar Y PT Sat LHe 1.6 bar C’ ALARM GHe 300 K, 1.1 bar M1/M3 GHe 20-50 K, 1.3 bar M2 GHe 4.5-300 K, 2.5 bar ALARM GHe 4.5-300 K, 2.5 bar E CFB GN2 300K, 2.5 bar Vac (SV not represented) CSOC Meeting 29 September 2004

  13. Main CFB Specifications • Electrical circuits: 1 x 13 kA and 2 x 600 A • Design pressure: 20 bar • Cdown/Wup typical GHe mass flow rate:100 g/s • C-down typical LHe mass flow rate: 20 g/s • 1.9 K Subcooling typical mass flow rate:12 g/s • LHe content in normal operation: 50 l (+ magnet ~ 320 l) • Inner buffer (handling of quenches): 550 l (~ 2,2 MJ, 14 bar, 8 K) • Hydraulic circuits to magnet interfaces with isolation valves. • Flanged hydraulic connections with double seals for magnet interfaces • Retractable sleeves for hydraulic interfaces surrounding electrical circuits ones • CFB is controlled by PLC, remotely operated. • Local interlocks ensure safety of personnel for magnet (de)connection CSOC Meeting 29 September 2004

  14. Overview of Operation • CTB operating modes: Cog Wheeling • Sequence of a magnet (de)connection • Tasks Tracking System • Priorities handling CSOC Meeting 29 September 2004

  15. Cog Wheeling (example) CSOC Meeting 29 September 2004

  16. Magnet (de)connection • Transport of magnet from SMA18 to SM18 • Fitting of anticryostats (if any) & Magnet Return Box • Transport of magnet to the test bench • Connection of superconducting cables • Connection of hydraulic interfaces • Connection of anti-cryostats • Mechanical anchoring of MRB • Closing of the interconnection sleeve • All checks (go/no-go) with the Task Tracking System • Reverse sequence of operations for disconnection CSOC Meeting 29 September 2004

  17. Task Tracking System 1/5 CSOC Meeting 29 September 2004

  18. Task Tracking System 2/5 CSOC Meeting 29 September 2004

  19. Task Tracking System 3/5 CSOC Meeting 29 September 2004

  20. Task Tracking System 4/5 CSOC Meeting 29 September 2004

  21. Task Tracking System 5/5 CSOC Meeting 29 September 2004

  22. Priorities • All 12 CFB’s are controled in order to share cryogenic resources,i.e. GHe circulation of CWS, LHe/Cold GHe return, Cold GHe pumping • This coordination is done by the Priority System which calculates in real time the CFB’s respective allocation of resources, according to a main priority list (1st to 12th ). • Therefore, 3 other priority lists are calculated by the Priority System: • CWS List: • CFB’s which are using the GHe circulation • Liquid/Cold return List: • CFB’s which are taking LHe and returning cold GHe • Pumping List: • CFB’s which are cooling down to 1.9 K. CSOC Meeting 29 September 2004

  23. Priorities:Max use of Cooldown Warmup capacity • The priority System distributes the CWS GHe mass rate flow among all the CFBs, taking care of total flow available from compressors and number of available CWU’s. • Examples: CSOC Meeting 29 September 2004

  24. Priorities:Max use of LHe Supply CSOC Meeting 29 September 2004

  25. Priorities:Max use of cold GHe return capacity CSOC Meeting 29 September 2004

  26. Priorities:Max use of 1.9 K pumping capacity CSOC Meeting 29 September 2004

  27. Priorities:Pressure control during & after quench CSOC Meeting 29 September 2004

  28. Priorities Issues Operation : • Easier control • Shorter reaction time • Reduced number of human mistakes • Anticipation of phases launches • Data Analysis • Resources Limitation Finding • Resources Optimization • Better average/maximum test rate CSOC Meeting 29 September 2004

  29. Last but not least: Safety issues • High Voltage electrical insulation • Impurities • Operation • Magnet failure CSOC Meeting 29 September 2004

  30. High VoltageElectrical insulation problems • Moisture on 13 kA current leads flanges ADDITIONAL HEAT EXCHANGERS CSOC Meeting 29 September 2004

  31. On 26 November 2003, during disconnection of magnet 2026 from TBE1, the feedthrough of one 13 kA current line was broken.A copper stabilizer of magnet was stuck to silvershoe of CFB.When magnet was moved back, the copper stabilizer pulled the CFB SC cable, therefore broke one feedthrough. In order to avoid an other similar problem, an insulating sleeve has to be inserted between CFB and MAGNET cables after each deconnexion (step added in traveler). Operation CSOC Meeting 29 September 2004

  32. Before Then: Impurities CSOC Meeting 29 September 2004

  33. Magnet • MB3004 passed all the tests (warm, cold) before the training campaign • It suffered for an inter-turn short circuit appeared during a quench at nominal • Results : meltdown of the cable and then of the cold bore CSOC Meeting 29 September 2004

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