AT-ACR B. VULLIERMECSOC Meeting 29 September Cryogenics for LHC Test Benches Safety Aspects Overview of the Test Station Overview of the Operation Safety matters: Experience Discussion

AT-ACR B. VULLIERMECSOC Meeting 29 September Overview of the Test Station Block Diagram General view Cryogenic Feed Boxes Cooldown/Warmup system

AT-ACR B. VULLIERMECSOC Meeting 29 September LP GHe Heater 200 kW CFB CCU 1 (IHI) (2005) CCU2 Linde Heater 1 30 kW COMP 1 COMP 2 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 GHe PUMPING SYSTEM CWU 1 C only CWU 2 C only COMP 3 (2005) Cryogenic Compound Line, 12 valve boxes (CCL) LHe WPU 1 Cooldown Warmup Line, 12 valve boxes (CWL) WPU 2 Heater 2 30 kW GHe <90 K GHeLN2GN2 GHe 40 bar GHe Recover y Other Utilities required for Magnet Tests GHe HP GHe Heater 30 kW INTERFACES WITH CRYOGENIC FACILITIES OF ZONE 18

AT-ACR B. VULLIERMECSOC Meeting 29 September CWL CCL CWU1 CWU2 HEATER SSS DIPOLE CFBs

AT-ACR B. VULLIERMECSOC Meeting 29 September Cooldown / WarmUp System 02TE TE 263

AT-ACR B. VULLIERMECSOC Meeting 29 September 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 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 80 K using 1200 g/s LN2 85 g/s 80 K are required for the cooling down of 1 magnet in 12 h Warming Up to 300 K Injection of preheated 320 K and heating of the returned GHe One 30 kW electrical heater: Max. flow rate: 190 g/s 290 K One 200 kW electrical heater: Max. flow rate: 175 g/s 80K. 90 g/s 320 K are required for the warming up of 1 magnet in 12 h

AT-ACR B. VULLIERMECSOC Meeting 29 September Cryogenic Feed Box

AT-ACR B. VULLIERMECSOC Meeting 29 September Set of 4 x 0.6 kA Current Leads 2-position pair of 13 kA Current Leads Heat Exchanger 2-position SC lines M1/M3 2 x Retractable Sleeves M2, M1/M3 CRYOGENIC FEED BOX AIR LIQUIDE

AT-ACR B. VULLIERMECSOC Meeting 29 September Sealing of CFB-magnet interfaces

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

AT-ACR B. VULLIERMECSOC Meeting 29 September 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.

AT-ACR B. VULLIERMECSOC Meeting 29 September PT X Y C’ M1/M3 M2 E N GHe 4.5 K, 16 mbar GHe 80 K, 14 bar GHe 320 K, 14 bar Sat LHe 1.6 bar GHe K, 1.3 bar GHe K, 2.5 bar GN2 300K, 2.5 bar Vac 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 ALARM GHe 300 K, 1.1 bar (SV not represented)

AT-ACR B. VULLIERMECSOC Meeting 29 September 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

AT-ACR B. VULLIERMECSOC Meeting 29 September Overview of Operation CTB operating modes: Cog Wheeling Sequence of a magnet (de)connection Tasks Tracking System Priorities handling

AT-ACR B. VULLIERMECSOC Meeting 29 September Cog Wheeling (example)

AT-ACR B. VULLIERMECSOC Meeting 29 September 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

AT-ACR B. VULLIERMECSOC Meeting 29 September Task Tracking System 1/5

AT-ACR B. VULLIERMECSOC Meeting 29 September Task Tracking System 2/5

AT-ACR B. VULLIERMECSOC Meeting 29 September Task Tracking System 3/5

AT-ACR B. VULLIERMECSOC Meeting 29 September Task Tracking System 4/5

AT-ACR B. VULLIERMECSOC Meeting 29 September Task Tracking System 5/5

AT-ACR B. VULLIERMECSOC Meeting 29 September 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 (1 st to 12 th ). 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.

AT-ACR B. VULLIERMECSOC Meeting 29 September 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:

AT-ACR B. VULLIERMECSOC Meeting 29 September Priorities: Max use of LHe Supply

AT-ACR B. VULLIERMECSOC Meeting 29 September Priorities: Max use of cold GHe return capacity

AT-ACR B. VULLIERMECSOC Meeting 29 September Priorities: Max use of 1.9 K pumping capacity

AT-ACR B. VULLIERMECSOC Meeting 29 September Priorities: Pressure control during & after quench

AT-ACR B. VULLIERMECSOC Meeting 29 September 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

AT-ACR B. VULLIERMECSOC Meeting 29 September Last but not least: Safety issues High Voltage electrical insulation Impurities Operation Magnet failure

AT-ACR B. VULLIERMECSOC Meeting 29 September High Voltage Electrical insulation problems Moisture on 13 kA current leads flanges ADDITIONAL HEAT EXCHANGERS

AT-ACR B. VULLIERMECSOC Meeting 29 September Operation 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).

AT-ACR B. VULLIERMECSOC Meeting 29 September Impurities BeforeThen:

AT-ACR B. VULLIERMECSOC Meeting 29 September 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