LHC Cryogenics: Strategy for re-cooling the 8 sectors after LS1 and key factors towards availability

Transcription

1 LHC Cryogenics: Strategy for re-cooling the 8 sectors after LS1 and key factors towards availability What did we learn last 6 years, What to be done, How, When S. Claudet on behalf of the cryo team 1/20

2 Introduction to LHC Cryogenics Total for 8 sectors: Compressors: 64 Turbines: 74 Cold Comp.: 28 Leads: I/O signals: PID loops: Pt 3 Pt 5 Pt 4 Pt 6 8 x 4.5K 24km & 1.8K Cryoplant Distribution Present Version K 130 t He inventory Pt 2 Pt 8 Pt 1.8 Pt 1 Cryogenic plant x 13.5 Magnets Distribution Pt 7 From LHC Magnet String test Sector 3.3km SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

3 Availability and origin of downtime 2012: - Excellent utilities & interface - Excellent mitigation of SEU - Continued improved Cryo availability Our operation team has now methods, procedures, good practice rules, clarified interfaces, training for newcomers, 15% turnover mastered SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

4 Just keep going! Why changing? Will it be different after LS1? 4/20

5 Cool-down before 1st physic run Cryo agony Show stoppers Miracle, then Oups! Progressive learning, from pain to relative success, it works! SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

6 Major work foreseen Repairs: Serious N2 and/or helium leaks in some cold boxes Serious helium leak in the cryogenic distribution line (QRL_45) Maintenance: Major overhauling ( hrs) for motors, compressors Specific maintenance for cold compressors bearings Filters, safety valves settings, cooling water circuits Valves, instrumentation, electrical cabinets Consolidations: Few on refrigerators (mostly related to cold compressors) All electrical feedboxes (DFB s) for main sc junctions About 100 valve plugs (BS_SAM, BS_34, few others) to be changed Thousands of electronic cards for temperature sensors + Controls: Hardware, Middleware, Software, supervision SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

7 LHC compressor station (x8) Only 1 stop/failure in 2012, >5 near miss! 4.2MW input power Bldg: 15m x 25m Oil/Helium Coolers Compressors Motors SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

8 Major impact of major overhauling Electrical cabinet (350 I/O) Filters 4.2MW input power Bldg: 15m x 25m Oil/Helium Coolers Safety valves SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

9 Progressive re-commissioning!!! Anticipation! Functional test with kind-of performance assessment of all sub-system before being connected to the next one and finally cooling the magnets Point 8 Storage QSCC QSCA QSRA QSCB QSRB QSCC Surface Shaft QURA QURC QUIC QURC Cavern Sector 7-8 Sector 8-1 Tunnel About only 1/3rd of the team will have seen the 1st cool-down! SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

10 Activities in the tunnel Besides our own cryo activities meca-instrum-r2e that will need specific commissioning Support to vacuum group for Helium leak tests Pressure test to validate the mechanical stability Flushing to make sure circuits/filters are clean Electrical quality assurance ELQA before cool-down + Permanent He signal & ELQA checks during cool-down SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

11 Pre-cooling to 80K with LN2 Heavy logistics: (done from 6h to 22h, 6 days/week) : 500 trucks (20 tons) for 7 sectors in 5 months : 400 trucks (20 tons) for 5 sectors in 3 months LS1: 500 trucks in 5 months SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

12 We should be able to cool-down a sector to nominal within a month (if no leaks nor electrical shorts on the way) SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

13 tons of helium ordered in 2008 with only gas storage, very delicate logistics just on time SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

14 Helium storage capacity in 2012 Gex 2 for CMS Point 5 w.r.t yearly market Eu 20%world 1xLHC 2.5%Eu Point 4 Point 6 Point 3 LHC Inventory: Point 7 - LHC + Cryo: 125 t (= 8 x 16t) (R) Point 2 Ferney Voltaire - Required for P control: 5 t - Total: 130 t St Genis-Pouilly P 1.8 P 1 Point 8 Storage capacity: Geneva - GHe tanks (300K-20B): 45 t (vol. = 51 t) - LHe tanks (6 units): 84 t We should be able to get 120 tons in 6 months (new buffer capacity) SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

15 Electrical feed boxes for current leads (DFB s) 48 Boxes, 1200 leads LSSL2 of the LHC Just an example of cryo tuning required as well at nominal temperature, estimations from 2 down to 1 wk / sector SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

16 There will be some quenches, at least to define or verify the future beam energy (>6TeV) (Spring 2008, 2.0 to 2.5 quenches/24h at 11kA considered) Next: Ready for cold check out and beams SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

17 When? THE reference! SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

18 LS1 summary schedule LHC CRYOGENICS - Overall Schedule LS1 Legend P18 Before sectors warm w Sector warm, cryo locked -out, ready for Interco consolidations P6 during warm-up of 56 end march Helium logistics 2014: 2At P8 least (He from 278 before months wup 81) end foreseen march (+1wk delay on 8 I Cryo-installations locked-out, ready for maintenance & projects 3 P8 (81) in April l Maintenance done, ready for cryo re-commissioning tests 4 P6: +2wks with water t Helium leak tests in sector per 10 2cryoplant 2 P6 original for plans functional tests P Pressure test P18 (2/wk) To remain at P18 in June'13: F Flushing of sector He from 34 & 23 (last 2) Cool-down of a sector, cryo tuning Required: 20 and re-commissioning 23 Total 80 t - 4.2t/Truck 23 (New request aligned on CRG-OD needs!!!) According to master schedule V1.5? => Most likely helium leak tests with lost helium => Time available for Re-commissioning cryo refrigerators (CD delayed by R2E) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec S12 w I 7.5m t l P F S23!CSCM! w I 9.5m t l P F S34 w I 10m t l P F S45 w I 12m t l P F S56 w I t 6.0m P F l l S67 w I t 5.5m l P F l S78 w I t 6.5m l P F S81 w I 7.5m t l P F >=6.5wks!!! New delay for Quad_diodes!!! 2013: operation, helium logistics, maintenance, some re-commissioning 2014: Full re-commissioning, cool-down (!), tuning, operation SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

19 Key factors towards availability We will (hopefully) remember what we did achieved before LS1! [AV>90%, maxi 95%] We will have (re-)gained experience with: Cryo re-commissioning, cool-down, powering tests Learning curve for availability with possibly (few) early mishaps to be corrected We will have to learn how to operate for >6TeV ( Amps, beam induced loads) with less cooling capacity margin as all refrigerators in operation (spares!), including specific tuning for transients We should profit from all repairs, consolidations, improvements done! SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

20 Summary We know now how to operate the LHC cryogenic system with a correct availability for beams of 95% All identified repairs-maintenance-consolidations are being prepared to be done in It should help! Complete cryo re-commissioning is foreseen before scheduled date for cool-down of corresponding sector This will help the (re-newed by 2/3rd) cryo OP team to get its new learning curve while preparing for energies >6TeV Target availability for next physics run: in the 90es SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

21 Flushing sectors before cool-down Dust Debris Kapton Reports And possible shorts in diodes! But the sooner the best!!! SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

22 SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

23 Cool-down: 5 from 300K 3 from 80K 4 months HWC Physics SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

24 Conclusion: Learning curves Once behaviour understood, easyer to set automatisms and procedures! SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20

25 Saved by reduced energy/intensity! + above 5 TeV, longer quench recovery Before LS1: With lack of spares (construction budgets limitations, teams to be educated on very specific HW) and long delivery time, we profit from stopped cryoplants to get specific spares for running ones LS1 and after: Operation-minded incentive from management to be completed with updated Process & equipment critical evaluation, and repairs/consolidations of identified weak points SC - 20Dec'12 LHCCryo LS1 recooling - Evian /20