LHC Cryogenics: “From cool-down & HWC to operation with beam”

1. LHC Cryogenics:“From cool-down & HWCto operation with beam” S. Claudet, for LHC cryogenics Extended LTC, 3 Mar’08

2. Content 3. Resources 2. Availability 1. Technical issues 4. Tools & Resources • How to operate up to 8 sectors together • Recovery after a quench: how much time does it take? Is expert intervention required? How can this be improved? • Equipment folder: tests results, handling of non-conformities,performance below specs, machine as commissioned vs. machine as nominal • Alarms/signals/SW available in CCC • Piquet/Experts availability LHC Cryo - extended LTC

3. Major Technical issues (1/2) • Being implemented before HWC: • DFB’s: level gauges, anti-condensation, valves and filters • Stand-alone levels: short term solution being applied (evolution ?) No remaining technical limitations so far • To be tested during HWC: • Re-connection of line B (pumping) below 50 mbar • Quench lines at odd points in case large number of cells would quench • Heat loads, to quantify the remaining capacity for beam induced loads w.r.t previsions Time slots to be allocated at best globally LHC Cryo - extended LTC

4. Major Technical issues (2/2) • Identified, not yet launched: • P8 ex-LEP 4.5K refrigerator: subcooler to be replaced • QRL line D temperature: 20K is an average, not yet all-along • UX85: Tolerance to single-events for PLC’s and electronics Most of necessary hardware available, time slot to be decided • Identified, but to remain for some time: • Helium inventory: from 20l/m to > 25l/m • Line Y heat-exchanger: if discovered after cool-down (1, 3, ?) • Stand-alone levels: long term solution ? • Robustness of some electronic cards and features ? Direct impact on recovery time, not on performance for the 1st run + Time slots for preventive maintenance, or wait and repair strategy ? LHC Cryo - extended LTC

5. Availability: From 7-8 to others Cryo Maintain ARC: 63% (Since 14Jan08) Cryo Maintain LSS: 70% - 93% (Since 21Jan08 or 01Feb08) Stand-alone levels DFB’s valves ELQA 7-8 (2007): 85% for LSS (>1st May’07) 66% for ARC (>1st Jun’07) Target 4-5: 90% for LSS 80% for ARC For future sectors, we maintain our objectives with work on recovery time But as well we try to give Cryo Start/Maintain earlyer ! LHC 45: MTBF: 11 days - MTTR: 48 hrs LHC Cryo - extended LTC

6. Recovery Time after Limited Resistive Transitions Now: 2 to 3 times slower (Predictions at design stage) Achieved or achievable • More than 14 cells or full sector:recovery up to 48 hours • In case of fast discharge (even w/o quench): 2 h recovery (heating due to eddy currents). LHC Cryo - extended LTC

7. Recovering a quench 2. Larger He Qty released (criteria!): > Pre-cooling required before LHe re-filling > Perturbation of global process, to be done by expert 1. Small He Qty released: > Usual 1.9K cooling valve at max. opening > Self adapting and global process kept OK Alternative 1. considered less perturbating for HWC, ideas to make it automatic and < 10 h for a dipole > 10 kA LHC Cryo - extended LTC

8. LHC Cryogenics availability Target for LHC operation Target for HWC Rough ideas for discussions considering independent origins Reminder: a cryogenic system takes time (hours) to recover any kind of stop (seconds) LHC Cryo - extended LTC

9. Availability • MTBF: • Less perturbations due to EL or CV systems • First results of global effort of teams to work together • To be further improved for beams to circulate one day! • MTTR: • Experience so far with cold compressors helped pump-down to 15mbar to be successful at each try! • Conservative approach to prevent spoiling 15mbar conditions (2hrs more versus 2 days lost!) • Ideas to make it more automatic are being tested • We will never compensate the time delay for Y lines ! • Quench recovery: • A simple and safe solution is being studied for automation LHC Cryo - extended LTC

10. Affectations LHC Cryo CRG-OA LHC Cryo OP No Tel SdC Team Leader: S. Claudet + 2 posts (C) identified, not yet through ! + M. Soubiran (Analyse fonctionnelle) + Industrial partner teams in local control rooms (≈ 23 personnes ALLS) LHC Cryo - extended LTC

11. Working periods • CERN staff: • Normal working hours + overtime when needed • On-call service: 1 Operator (direct) + 1 Engineer (back-up) Now: mostly to guarantee safety and helium inventory • Expert assistance in CCC for specific tests • Industrial partner: • Normal working hours + overtime when needed • On-call service: 1 Operator (direct) + 1 Operator (direct) • Afternoon shifts (14h-22h): 2 Operators, mostly for LN2 trucks • Saturdays: 2 Operators, for LN2 trucks and interventions HWC activities already possible up to 22h and Saturdays ! Investigations for 1 Operator in CCC (2 shifts) after logistics with LN2 trucks LHC Cryo - extended LTC

12. Resources • Cool-down of 8 sectors: • Should be OK with structure in place • HWC of many sectors in parallel: • Already now, up to 22h and Saturdays • Spring’08, two shifts (week) and Saturdays (day) • First beams: • We do not have CERN staff (alone) for any kind of shift • Various type of shifts possible via our industrial partner, with CERN experts and local control rooms (day time) in back-up • After July 2009: • End of present operation contract, with in-sourcing as reference solution, to be re-evaluated in 2008 LHC Cryo - extended LTC

13. Challenge for Spring’08 Preparing tools to help having a quick global overview, and identify what needs to be delegated to local tuning teams or consolidated LHC Cryo - extended LTC

14. Summary • Technical issues treated to allow HWC and first LHC beams • Methodology for cryogenic commissioning in place • Learning curves for transients on the good way, with automation in progress and team experience growing • Work started to safely improve “Cryo start” statistics and availability • OP team structure adapted in January 2008 to face parallelism (x8) • Imminent presence in CCC (2 shifts during week) • We can adapt and redeploy resources until July 2009, (incl. 2 x 5x8) • Longer term future to be consolidated LHC Cryo - extended LTC