1. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP1 SECTOR COOL DOWN AND CRYOGENIC COMMISSIONING L. Serio

2. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP2 Outline Introduction What are the requirements and constraints before and during the tests Utilities, fluids, resources, organization, safety Test program and technical challenges to be addressed Or what we could not test during individual sub-system commissioning and string tests The expected performances and limitation Steady state, transients and recovery What happens afterwards … Conclusions

3. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP3 introduction LHC Test String 1 (45-m long): 1994 – 1998 12’000 hours operation, 170 quenches, 5 C/W Cooldown and commissioning: 2 - 3 months and 2 FTE (+ 4 IS)  QRV and cryogenics flow scheme simplification LHC Test String 2 (100-m long): 2001 - 2003 8’000 hours operation, 42 quenches, 3 C/W Cooldown and commissioning: 2 months with 2 FTE (+4 IS)  Quench propagation/recovery, superfluid and supercritical helium loop validation LHC sectors commissioning (2 x 3000-m long): 2006-2007 Overall more than 2000 hours/sector, ?, 1 C Cooldown and commissioning: 2-3 months with 12 FTE (+18 IS)  Cool down time and cooling flow distribution optimization, superfluid helium loop commissioning and optimization with adjacent cells cooling, cooling power distribution and transient disturbance between individual cooling loops, quench propagation and recovery for more than one cell

4. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP4 Constraints Physics and available cooling power:  cannot cooldown in less than 14.2 days Safety: Cryogenic fluids  Cold burns – negligible risk (all discharges away from personnel)  Asphyxia – negligible risk  Need oxygen deficiency monitoring installed and commissioned Radiation (activation of dust, impurities, helium [tritium])  No concern for sector test and machine start-up but radiation protection monitoring and sampling system should be installed for long term assessment prior to first injection test  Missing equipments/systems  Avoid cooldown with missing components, otherwise:  Always ensure buffer and inert volume between process and air  Access  No access during pressure tests  No access (restricted?) during first cooldown (SG constraint?)  Restricted access during subsequent cooldown and magnets filling  No access with magnet powering above 3 kA ?

5. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP5 Cooling towers Compressed air Vacuum 10 -3 mbar Cooling and ventilation 600 m 3 /h of water Helium and nitrogen 12 t of He; extra storage by end of 2006! 1300 t of LN2 (a 20 t cont. every 4 hours) Electric power about 4 MW; 25 GWh/year Requirements (per sector) CRYO Controls&instr.: Networks, fieldbuses, PLC, SCADA, process control software, instrumentation CRYO OK Total peak power up to 18 MW

6. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP6 Equipment to be monitored/controlled (per cryogenic island [2 sectors]): 2 x 4.5 K refrigerator; 2 x 1.8 K refrigeration unit; 1 interconnection box 2 x 3 km cryogenic distribution line; about 50 cryo systems (this is comparable in size to the all LEP cryo system but more complex) Resources: Conditioning/leak/pressure testing: 1 x 8; assistance vacuum group 1 Technical responsible; 2 operators (IS) Cooldown and cryogenic commissioning: 1 x 8; on-call service 1 Engineer in Charge; 2 Techn. resp.; 4 operators (IS) Powering: 2 x 8 shift; on-call service on 3 rd shift 1 EiC; 4 Techn. Resp.; 8 operators (IS) Total for 13 months planning: 3 EiC; 9 Techn. Resp.; 18 operators (IS) Resources for cryo commissioning !!! 2 x 8 shift for powering does not correspond to 2 x 8 shift for cryo !!! 10 weeks from start of cooldown to CRYO OK for powering 2 weeks in parallel with powering tests for fine tuning with current and quench recovery !!! Time for conditioning/cleaning QRL and magnets not taken into account !!!

7. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP7 Preparatory (ongoing) work  (Cryogenic Functional Analysis WG):  SCOPE: Define the functional analysis of the LHC cryogenic system and establish the corresponding logic and documentation  The FA must be defined to first maximize the system availability and secondly minimize the operating cost  Establish detailed and global Process and Flow diagrams  Define the cryogenic system overall process  Identify possible flaws in global process  Produce global process control logic  Specify supervision and monitoring view  Produce functional analysis of the cryogenic system for the LHC sectors commissioning and operation

8. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP8 Cryo sub-systems commissioning strategy Individual components and sub-systems are manufactured in industry Preliminary qualification is performed – for some sub- systems - in dedicated tests facilities After delivery and installation at CERN each sub-systems is individually commissioned and qualified for operation The commissioned and qualified sub-systems are then used in a cascade way to commission dependent sub-systems Each sub-systems is individually controlled and it exchanges main status parameters for connection disconnection with slave and master sub-systems for interlock and start-up The collective behavior of the cryogenic sub-systems is progressively tested and the overall process established

9. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP9 Cryogenic subsystems commissioning “New 4.5K” refrigerators: all commissioned ready for operation “Ex-LEP” refrigerators: major overhauling and adaptation for LHC in 2005-06 commissioning ready for operation QUI: installation and commissioning 2005 consolidations required (filter system, heater, controls) ready for operation 1.8 K refrigeration units: installation and commissioning 2005-06 ready for operation Cryogenic distribution line: installation and partial commissioning (first 1.2 sectors) no functional tests at working temperature on components and instrumentation pressure and leak tests would require commissioning and flushing of circuits to avoid contamination (1 additional week needed) Arc magnets, DFB’s, RF cavities, DSL, standalone magnets, inner triplets pressure and leak tests would require commissioning and flushing of circuits to avoid contamination (1 additional week needed) Global system Overall collective behavior assessment and validation Control loops fine tuning and sub-system information exchange for start/stop/interlock Control process logic commissioning and validation

10. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP10 Technical challenges still to be addressed: Overall cryogenic commissioning Magnets string and DFB’s instrumentation commissioning Magnets string, DFB’s and RF cavities commissioning QRL commissioning Logistics for fluids (liquid nitrogen and helium) for a full sector Overall collective behavior of systems (new from string): Cool down time and cooling flow distribution optimization Superfluid helium loop commissioning and optimization with adjacent cells cooling Cooling power distribution and transient disturbance between individual cooling loops Quench propagation and recovery for more than one cell Establish and validate interlocks and process for sub- systems collective behavior String experience + Cryogenic Functional Analysis WG

11. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP11 90 K commissioning of cryogenics 1 Tests at warm 3 Cooldown 300 K to 90 K 4 Cooldown 90 K to 4.5 K and filling 5 Cooldown 4.5 K to 1.9 K Conditioning of cryogenic circuits B1 Leak and pressure tests of all the cryogenic circuits A2 check consistency of PLC and supervision database, verify instrument chain from supervision to sensor Verification of sector instrumentation and controls Verification of cryoplant instrumentation and controls A1 Nominal conditions on thermal screens Start 1.9 K refrigerators Pumpdown of line B Operation at nominal temperature (1.9 K) 6 Tuning of all active control loops Flow distribution and cooldown optimization E Verification of nominal temperatures, pressures and flows –tuning of individual loops dynamics – verification of process control logic and stability H D Wait 10 -2 mbar 2 Pumping of insulation vacuum Start compressor station B2 C Open JT-valves for cooldown F 293 K 4.5 K CRYO OK G

12. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP12 Theoretical cooldown of a LHC sector Start of ACS and DFBs cooldown 300-4.5 K

13. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP13 Final cooldown to 1.9 K Once at 4.5 K and after verification of equipments, systems and process control logic, launch the final steps: start of 1.8 K refrigeration unit, pumpdown of line B, filling and cooldown 4.5-1.9 K Theoretically 2 additional days once cooling flow distribution, PID tuning, sensors troubleshooting, process control logic, collective system behaviour, are assessed and validated. Filling Cooldown 4.5-1.9K

14. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP14 Expected performances and limitations: Magnets temperature control (more than 30 control loops/sector)

15. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP15 Valve opening Flow Inlet Pressure Current 12-05-2003 Expected performances and limitations: Operation of HTS current leads and DFB’s (more than 150 control loops per sector)

16. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP16 Quench propagation limited to 1 cell; several cells or full sector up to 48 hours 123 Number of cells [-] Cooldown 4.5-1.9 K Filling 70-100 % Filling 0-70 % Cooldown 30-4.5 K Expected performances and limitations: quench recovery 123 0 1 2 3 4 5 6 7 123 Recovery time [hours] < 3 kA 3 kA < x < 9 kA> 9 kA

17. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP17 What could go wrong In principle, the production side of the cryogenic system should have a low impact (except on sector 2-3) on the commissioning time: Redundancy of systems Available spare cooling capacity Proven reliability with better than 98 % availability on systems commissioned so far However, failure of sub-systems and components can not be ruled out completely and could result in few days delays to switch to redundant system or component and to adapt to new configuration The distribution system (QRL) and the tunnel components would certainly have lower availability as they will be tested for the first time Worst failure would be the loss of insulation vacuum on the QUI or QRL as well as the refrigerator in point 2 or DFB’s for magnet powering (time to investigate, repair, + recovery time) Most likely failure would be filters blockage on the QUI during or after the first cool down and magnets quench due to accumulation of impurities (1 day + recovery time) (consolidations under study – allow time for circuits conditioning before cooldown)

18. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP18 Recovery time to nominal operation after a failure The cryogenic recovery acts as a time amplifier - utility stop: rec. time=6 hours + 3 x “utility stop length” - bad insulation vacuum or leaking QRV: rec. time = 15 x “utility stop length”  Controls : ? Complete new control system ? Ethernet dependent (control loops, PLC communication)  Required performances, reliability and robustness of the control system is not “yet” up to requirements  Utilities: ? Water, compressed air, electricity, … might have a « big » impact on commissioning time

19. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP19 How time can be saved Preparation work: documentation, procedures, risk analysis, process control logic definition and verification prior to cooldown, instrumentation verification at warm, maintenance of equipments and spare parts availability, etc.  It REQUIRES RESOURCES!!! Extensive testing of subsystems prior to global commissioning (i.e. QRL, DFB) Ensure that the “experts” that have designed and built the systems are available during commissioning for support and consolidation work Ensure that the trained IS operators on the ALLS contract are not “disappearing” (physically and mentally) towards the end of their contract (it happens to coincide with the end of the HC!) Reduce the number of control loops / circuits to be commissioned to the minimum necessary for the first year machine operation (it would have to be done afterwards!)

20. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP20 What happens afterwards How to leave the sectors: Baseline is: stop cooling and natural warm-up anyway minimum standard preventive maintenance would be required during SD If active warm-up at 300 K: additional IS operators and technical staff If cold standby at 75 K: 110 kChF/sector/month (elec. Power) + additional IS operator + fluids, maint., etc. (about 200 kChF/month) If at nominal temperatures 150 kChF/sector/month (elec. Power) + additional IS operator + fluids, maint., etc. (about 400 kChF/month) and 2 CERN Technical staff PLUS the requirements of additional helium and storage

21. HC review - 12 May 2005Luigi SERIO - AT/ACR/OP21 Conclusions Cryogenic system overall performances and reliability have been checked during dedicated individual sub-systems and String tests and are under commissioning prior to sectors tests (except for tunnel/sectors components) Shortcuts during sub-systems and sector commissioning is increasing Commissioning and start-up time  (equipments ready for operation) Reliability of the cryogenic system Training time for operation and maintenance crews Overall process and collective behavior as well as the process control system performance and robustness need to be assessed and optimized during sectors test Cryogenic fluids logistics and in particular helium inventory storage needs to be put in place and assessed Resources: IS operators – use present contract (end 7/2007 !) + up to 11 op Staff – 3 missing Due to the system complexity and shortcuts on individual systems tests, the validation of commissioning time and required resources estimates can only happen after first sector test