LHC Cryogenics for sector 45 and Perspectives S. Claudet, for LHC cryogenics HWC Review, 28 Fev08.

LHC Cryogenics for sector 45and

Perspectives

S. Claudet, for LHC cryogenics

HWC Review, 28 Fev’08

S. Claudet - 28 Feb'08 LHC Cryo - HWC review for sector 45

Content

• Achieved performance and plans

• MTBF, MTTR and quench recovery

• Consolidation activities

• Manpower and distribution

• Summary

Cryo Performance & Operation- Availability for cryogenic system- Recovery time after quenches: what can we expect?- Operation overnight and over the weekend: is it possible?- Operation with several sectors in parallel, what will change?- Presence in the CCC - Level measurements: Correct Helium level for operation?


LHC sector 4-5: 1st Cool-down (2007-2008)

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Time [days]

Temperature [K]

LHC sector 4-5: 1st Cool-down (2007-2008)

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Time [days]

Temperature [K]

LHC sector 4-5: 1st cool-downMore than 8 months in total, for about 8 weeks of powering !

X-mas

Cool-down 80K - 4.5K

Improved cool-down speed w.r.t 7-8( Now much closer to our final expectations

as for 5-6)

Cool-down 300K - 80K

Leaky flexible hoses in DFBA’s and hesitations due to PIM’s

findings during summer

Towards 2.1 K

HWC @ 1.9 K

Major perturbations: - Air leaks into sub-atm circuits - Levels in stand-alone magnets - Tuning valves for DFB’s

Warm-up started


1.0

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07-Jan-08 14-Jan-08 21-Jan-08 28-Jan-08 04-Feb-08 11-Feb-08 18-Feb-08

Temperature [K]

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Pressure [bar]

SEC45_AR45_TTMAX.POSST SEC45_AR45_TTAVG.POSSTSaturation Temperature QURCB_45_PT240.POSST

LHC 4-5: Evolution of temperatureQuench of dipoles

21Jan’08

Stop of 18kW due to oil system

25Jan’08

Stop of 1.8K Ref. unit due to vacuum interlock

Quench of Quads

13Feb’08

Stop of 1.8K Ref. unit due to water stop US45

MTBF: 11 daysMTTR: 48 hrs

Global powering

>=Wk06: ARC + RF + LSS5L + LSS4R


Availability: From 7-8 to others

For future sectors, we maintain our objectives with work on recovery timeBut as well we try to give Cryo Start/Maintain earlyer !

7-8 (2007): 85% for LSS (>1st May’07) 66% for ARC (>1st Jun’07)Target 4-5: 90% for LSS 80% for ARC

ELQA

Cryo Maintain ARC: 63% (Since 14Jan08)

Stand-alone levels

DFB’s valves

Cryo Maintain LSS: 70% - 93% (Since 21Jan08 or 01Feb08)


Recovery Time after Limited Resistive Transitions

• 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).

(Predictions at design stage)

Achieved or achievable

Now: 2 to 3 times slower


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

Alternative 1. considered less perturbating for HWC, ideas to make it automatic and < 10 h for a dipole > 10 kA

1. Small He Qty released:

> Usual 1.9K cooling valve at max. opening

> Self adapting and global process kept OK


Availability• MTBF:

– Less perturbations due to EL or CV systems– First results of global effort of teams to work togetherTo 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


Content





• Summary


Consolidation activities• Valve plugs:

– Changed for all JT valves (CV910) => Nominal features now– Evaluation to change few valves at return module (line D)

• Refrigeration and local distribution:– P6_QULA crossed lines fixed early 2008– P6_QSRA heat-exchanger by-pass done (Feb’08) [P4 in Mar’08]– P2_QURA subcooler being changed [P8 to be decided]

• Air leak to sub-atmospheric circuits:– More systematic checks before being sub-atm. organised– Investigations for minor adaptations on QUI’s


Consolidations on DFB’s

Anti-condensation systems on current leads chimneys

Calibrated level gages and protective covers

600A control valves:mass flow vs input signal

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input (%)

Flow (g/s)

As delivered (Imin=227.5 mA)

Imin = 213.5 mA

nominal operation flow

standby flow

T=293 KPin = 1.2 barDP= 200mbarValve #809

Electromagnetic proportional valvesPulse width modulation command signal, no feedback, sensitive to DPMax flow 0.05 g/s at DP=33mbar

Spare valves being gathered, ready for exchange

Possible adjustment being tested

Online filters being tested


Levels for stand-alones

LHe level gauge

Cold massLarge impedance !

Proposal for the time being:- All stand-alone magnets are being equipped with valves @300K- Capillaries will be installed on requestBUT individual adjustment of setting required! (evolution ?)

Set-point


LHC Cryogenic commissioning• 4.5K stand-alone magnets

– Cool-down to < 10K– Adjust instrumentation LT/EH– Control LHe at 50% Fill-up and boil-off to determine

appropriate set-point

• DFB’s– Cool-down shield (if any)– Cool-down leads at 150K, then

cool-down phase separator– Adjust instrumentation LT/EH– Control LHe at nominal Fill-up and boil-off to determine

appropriate set-point Tuning of Temp. control loops

• 2 K magnets in ARC– LT/EH at return modules– LT of SSS in ARC – EH at lowest point– EH of cold masses & beam screens Possible pump-down and cool-down

of magnets, including tests with cold compressors

Identified and tuned for sector 4-5,

Now being implement for sector 5-6 during the two weeks after ARC magnets @ 4.5K


Content





• Summary


No Tel SdC

P2 - P4 P6 P8 - P18U. Wagner G. Ferlin F. Millet

JP. Lamboy (P2/2-3)S. Junker (P4/3-4)

+ C. Parente (Apprentissage)

L. Herblin (P18/1-2)

A. Eychenne (P2) G. Vincent (P6) E. Lussi (P18)

N. Navion (P4) E. Millet (P8)

Affectations LHC Cryo CRG-OA

LHC Cryo OP

P18 P2 P4 P6 P8

70081 79240 79440 79640 79840

75084 79241 79441 79641 79841

+ M. Soubiran (Analyse fonctionnelle)

Team Leader: S. Claudet

+ Industrial partner teams in local control rooms (≈ 23 personnes ALLS)


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


Challenge for Spring’08

Preparing tools to help having a quick global overview, and identify what needs to be delegated to local tuning teams


Summary• All cryogenic features of sector 4-5 have been tested and validated,

except multi-cell quenches!

• Learning curves for transients on the good way, with automation in progress

• Methodology for cryogenic commissioning of DFB’s and cryogenic instrumentation started for sector 4-5, now in place

• OP team structure adapted in January 2008 to face parallelism (x8)

This continues to pay now, already for sector 5-6 [and 7-8, 8-1, 2-3] Once cool-downs are well advanced, ideas to redeploy resources

LHC Cryogenics for sector 45 and Perspectives S. Claudet, for LHC cryogenics HWC Review, 28 Fev08.

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