Cryomagnets , Interconnections, Superconducting Circuits:

Technology Department

Chamonix 2011 LHC Performance Workshop

Cryomagnets, Interconnections, Superconducting Circuits:

24th of January 2011

What to do in 2012/13 if you are not consolidating splices ?

1/23J.Ph. Tock




• Context : The impact of these “special” interventions• In-situ work or cryomagnet replacement ?• Reasons for an intervention:• Vacuum related issues• Cryogenics related issues• Electr(omechan)ical integrity • Beam optics• DS Collimators•Miscellaneous• How many cryomagnets exchange? Spares?• The special interventions team and the work location• Conclusions24th of January 2011


2/23J.Ph. Tock



Context : The impact of these “special” interventions


Cryomagnets, Interconnections, Superconducting Circuits:What to do in 2012/13 if you are not consolidating

splices ?

Limited space

Shared human resources

Limited time (Minimise the impact on the shutdown duration)

Interventions on the same circuits

3/23J.Ph. Tock



In-situ work or cryomagnet replacement? (1/2)



splices ?

Many operations with > 6 different teams:IC, ELQA, VSC, Survey, BLM, QA,… and an heavily interleaved sequence Actions on circuits sometimes not sectorised over 3 km (beam lines, cryo lines) Also technical and schedule interferences

Sequence touches 4 half cells (216 m)

4/23J.Ph. Tock



In-situ work or cryomagnet replacement? (2/2)



splices ? All cryomagnets are not equivalent:

By increasing difficulty:- Standard cryodipole- Standard SSS without jumper- Standard SSS with jumper- DS(6kA) cryodipole- DS(6kA) SSS without jumper- DS(6kA) SSS with jumper- Cryoassemblies connected to a DFBA- DSs @P6 are specific (No Q7, Jumper on Q10 instead of Q9 …)- LSS ? (Variable-No rule)

For a “standard” cryodipole:Duration: 6 weeks from opening of IC to reclosure if non-stop work

considering one extended day (12 hours) in one shiftWorkload: About 600 man hours per standard cryodipole replacement

Welders, mechanics, electromechanics, ELQA, QA, leak tester

Less if consecutive magnets5/23

J.Ph. Tock




Vacuum related issues (1/3)



Leaks

Subsector is localized but not the exact leak originTime is required before opening & during the shutdown for leak detection/localisationPresent status : about 20 leaks / 11 are important / 1 is critical (A27L4)Usually, repairable in-situNew leaks could appear before the next long shutdown or be created by the warm-upTypical sequence: Leak detection / confirmation on each subsector during warm-up Opening of the interconnections Leak localisation (Requires circuit pressurisation: Safety & Coordination) Leak repair Repair validation

Conclusion: Work on all leaks to improve the situationOnly one cryomagnet could have potentially to be exchanged (A27L4)

6/23J.Ph. Tock







PIMs :-Buckled during warm-up : based on last warm-up after SSS displacement : ≈ 18 (RF ball test)-Heavily damaged : ≤ 10-Preventive replacements :

+ Arc extremities18/32 in baseline+ Not in the baseline: QQBI and QBQI close to a SSS with vacuum barrier (356 or 862) to decrease the risk of bucking in case of local warm-upConclusion:

About 45 PIMs are considered to be replaced

Low risk of failure in case of local warm-up that could require venting to replace the failed PIM and a subsequent scrubbing run (≈ a week)

A non-conformity of the RF fingers during their fabrication can lead to a failure of the component during the warm -up

7/23J.Ph. Tock







Nested bellows:About 55 small damages identified / 2 are heavierInspection will be carried out (VSC) to confirm that they do not need to be changed.Useful only in case of cryogenics operation error.Can survive a few accidental cases No replacement plannedBeam screens: One with leaking cooling capillary (S81): 2 were bypassed for symmetry No need for intervention Wrong type of beam screen (saw-teeth profile): 12 MBs/2 SSSs mainly in 34This could be an issue for cryogenics and electron cloud build-upVSC follows that with ABP & CRGÞNo replacement planned so far but impact in terms of resources described later ; Would mean 14 cryomagnets more to remove and surface work

QBQI.10L5, NCR 831037, nested bellows V2

8/23J.Ph. Tock



Consolidation of SAM Helium level gauges



splices ? Cryogenics related issues (1/3)

Details in ECR: LHC-LQN-EC-0001Level gauge reading was not stable

Existing capillary replaced by a larger metal hoseIt is planned to consolidate the 2 remaining ones (Q6R2, Q6L8) during the long shutdown

Repair of leaking Y-linesIt is planned to consolidate the 2 known cases (S78:17-19R7 & S81:19-22R8) during the long shutdown

9/23J.Ph. Tock



Installation of Pressure Relief Devices




To be installed on cryodipoles (DN200) during next shutdown in 23, 45 (part), 78 & 81: ≈ 600 units and on 2 SAM (DN160)

10/23J.Ph. Tock



Triplets braid




Cryo-InstrumentationAccess will be given to allow cryo-team to intervene

L1 R1 L2 R2 L5 R5 L8 R8NCR 982513 982506 982524 982518 982511 982525 982512 982517Action Remove Install Remove Install Install Remove Remove InstallStat./Prior. 1 Done 2 2 Done 1 2 2

3 weeks of work per triplet (not full time)To be done in second part of the shutdown (ALARA)Priority 1 are included in the baseline (HL exp)Priority 2 will be done if time is available 11/23

J.Ph. Tock





splices ?

Consolidation of the Connection Cryostats

Electr(omenchan)ical integrity (1/4)

The proposed plan is :•Measure and if necessary consolidate the CC 11L8•Consolidate the CC in 11L3 (If DSColl. not installed) & 11L1•Measure / inspect all the CCs to check no displacement

Details in ECR: LHC-LE-EC-0003

Risk of short to ground on main BB due to supports displacementAddition of extra insulation to go up to ultimate energy

12/23J.Ph. Tock





splices ?

Special splices:-600 A: in 78 : sampled inspections -6kA:(see presentation by F Bertinelli, LHC Splices Task Force)Opening for inspection of line N boxes not fully documented (sampling) and/or 8L and/or possible outliers found during splice mapping for inspection and possible consolidation-13 kA (DFBA): access and one specific case


Circuit issues (Open, high R)

Circuit Sector RemarkRCO.A81B2 81 Circuit is openRCBH31.R7B1 78 Circuit is too resistiveRCOSX3.L1 81 Circuit is open

• Investigation will be carried out• Some tests could be required before warm-up• Repair procedure to be defined• New issues could occur

13/23J.Ph. Tock





splices ? Cryomagnets issues: High internal splice resistance


No change of the splice resistance even after this extensive fatigue test in SM18

To be analysed in the LHC machine in details

From Zinur Charifoulline

Why should a magnet with a high internal splice resistance be replaced ?

Scheme from C Scheuerlein

Note small value !

QuadsDipoles

Not for cryogenics reason (OK for extra heat load) Not for electrical reason For mechanical reason# to exchange (proposal) + 8 dipoles (4A&4B) in S12&23) & 1 SSS (in S34) + Test programme Reduction by 50 % of inner resistance 14/23

J.Ph. Tock

To be disconnected for DS Coll installation





splices ? Cryomagnets issues


# to exchange (proposal)

+ 5 dipoles15/23

J.Ph. Tock

Dip ID Sector Issue Status1007 78 Breakdown at 1.6 kV Diagnostic (IFS) then exchange if not repairable in tunnel1263 67 IFS wires Inspect then likely repairable in the tunnel1372 12 IFS wires Inspect then likely repairable in the tunnel2007 78 QH likely damaged Diagnostic (TDR) then advisable to exchange2138 45 QH likely damaged Diagnostic (TDR) then advisable to exchange2214 45 QH likely damaged Diagnostic (TDR) then advisable to exchange2395 12 IFS wires Inspect then likely repairable in the tunnel2413 12 Weakness in 3 HF QH Advisable to exchange3708 23 IFS wires Inspect then likely repairable in the tunnel

Has also a high inner splice resistance




Beam optics



Wrong SSS types (S34): [LHC-LQA-EC-0004 M Modena] • 2 circuits are degraded (one is missing) (Q23,27,28,32 R3): [2 with jumpers]• MQS: Q23,27• MO: Q28,32Q5L8 : Warm corrector installed (78)

• To be replaced by a new Q5 L8

Priority to be given to RQS circuit (ABP input)

# to exchange : Proposed baseline : 2 (Q23R3, Q27R3)

16/23J.Ph. Tock




DS Collimators (See previous presentation by V Parma)



# to “exchange” :Baseline : 32

32 cryo-assemblies to be:• Disconnected• Brought to surface• Reworked• Reinterconnected

IC to cut # 28 Some special ones (DS)

Jumpers to cut # 6 5 to reconnect (Cryoextensions)

Cryostats to move # 26 7 Longitudinally / 6 RadiallyDFBA to move # 2 Affect also warm regionDS Collimators # 4 TCRYONew cryostats # 3 1 CC’ of ≈ 9 m lengthJumper longi motion # 4 DFBA & Q7: Not standardModif line N # 6 (8)

Involves surface work

17/23J.Ph. Tock



Miscellaneous



splices ?

BPM cables checks and repairsRP samples : See ECR LHC-LI-EC-0001 for detailsRecover and measure some of them ;New ones to be installed ?New issues appearing before long shutdownDetected during operation (Higher L, E, time…)Non-conformities generated during the long shutdown

18/23J.Ph. Tock



•How many cryomagnets to exchange? Spares?



splices ?

19/23J.Ph. Tock

MB SSS Tot1 8 1 9 High inner splice resistance To be confirmed after tests/study2 5 0 5 Electrical integrity Between 1 and 93 0 2 2 Beam optics Restoration of MQS in 34 only4 1 0 1 Leaks Depending on repairability5 0 0 0 Reversed beam screens Not considered but could be 14 !6 16 8 32 DS Collimators Not counted in total

TOTAL 14 3 17 DS Coll excluded

# Quantity Reason Remark

For MBs, spares should be available.If reversed BS to be changed, this will have to be done in SMI2

For SSSs, 3 should be available before the start of the shutdown (2012)A balance between time saved and procurement of new cryostat components needs to be done Work at the surface will be required to rework the extremities of removed cryomagnets



The special interventions team



splices ? Function At CERN Missing Total WorkCoordinator 0.5 0 0.5 External interfacesTeam leader 1 0 1 On-siteExpert welder 1 1 2 All types of weldsWelder 0 1 1 AssistantWelders Automatic and manual (including QA,…)Expert electromechanic 1 0 1 Ultrasonic weldsElectromechanics 1 4.5 5.5 Electromechanics (Assistance in US welding, electrical insulation, line N...)Main splices Soldering, shunting,…Expert mechanics 1 0 1 Specialist in cutting (all types)Mechanics 0 4 4 Opening/closure of IC, thermal insulation, assistance in cutting,…Logistics 0.5 1 1.5ELQA Krakow Collaboration: Not in totalQA inspector 0.5 2 2.5 Endoscopy, electrical checks, traceability, inspections..Leak Test

TOTAL 6.5 13.5 20 < 1/3 experienced staff !!!

Train

TE-VSC

TE-MPE

EN-MME

Surface work (SMI2, 180) to be considered in addition. Change of cryomagnets with reversed BS would strongly impact [+ 5.5 FTE]

Ratio of experienced staff 20/23

J.Ph. Tock

*Based on 12 months between opening of the first IC and closure of the last one



The work location



splices ?

21/23J.Ph. Tock

5

182

3

4

7

6

High inner splice

SSS

Highest leakElectrical integrity issueReversed beam screen(s)Beam opticsDS Coll.

Spread all around : work on leaks, PIMs,

SAM (He, DN160)Y-lines repair

CC Consolidation / InspectionDN 200 installationTriplet braid

Cryo-dipole

Circuit and splices issues



Conclusions



splices ?

22/23J.Ph. Tock

[FTE] [%]6.4 32% Cryomagnets Exchange4.5 23% DS Collimators4 20% Other planned work

5.1 26% New issues / NC20 TOTAL

The list of interventions on superconducting magnets and circuits (other than main splices consolidation) has been presented.Work is foreseen all along the LHCA team to carry out these interventions in the allocated time has been presented; the ratio of experienced staff (<1/3) seems lowThe assumed baseline does not include the exchange of cryomagnets with a reversed beam screen; adding this would have a major impact (resources, time?)Extra preparatory work is required to gain knowledge on inner splices with high resistanceA value of 30% for new issues & NC seems more realistic





splices ?

23/23J.Ph. Tock

Thank you for your attentionAnd to many persons for their infos, slides,

inputs, …

?



Spare slides



splices ?

Actions to get data to make an educated decision:Replace “only” magnets that will not withstand the LHC lifetime with

margin

- Detailed modeling of all the dipole inner splices and of the EM forces- Determine correlation between electrical resistance and mechanical strength (model and test on dedicated samples) and see if it is a relevant criterion[Will also define the correlation between cryolab and FRESCA resistance measurements]- Perform extra tests on cold masses (removed from tunnel ?) and/or on representative samples (No of cycles LHC lifetime equivalent) to validate acceptable resistance level (Approach used for the 6 kA pray-hand splices)

Splices test programme

24/23J.Ph. Tock



High internal splices resistances (1/5)LHC machine and spare status

The cryodipole specification is < 7 nOhm for dipolesAll were measured precisely several times (nQPS)

From Zinur Charifoulline

Dipoles: 40 (13A,27B) > 7.5 nOhm 18 (7A, 11B) > 10 nOhm (≈ 5 )3 (1A,2B) > 20 nOhm (> 10

)

Quads: 4(5) are > 10 nOhm1 [Q7R3] is > 20 nOhm

Spare dipole CM: Max: 21A, 23B (44 in total) ≈ 8.1 nOhmTested : 12A, 11B (23 tested) ≈ 9.6 nOhm


25/23J.Ph. Tock



High internal splices resistances (2/5)Experience so far

3 cases : 2 from the machine and 1 from the spares stock

Ref: LHC Project Note 430 : Dipole Magnet Splice Resistance from SM18 data

2334:(S12): R ≈ 100 nOhm Interpole splice D1

2303:(S67): R ≈ 50 nOhm Interpole splice D22420:(Spare): R ≈ 25 nOhm Interaperture splice

Pictures from H Prin (MSC-LMF)

Almost no soldering in splices


26/23J.Ph. Tock



High internal splices resistances (3/5)Degradation : Experience so far

Test report EDMS No1008959 : Splice Resistance measurements in SM18 : 2303

(TE-MSC-TF)

2303:(S67): R ≈ 50 nOhm Interpole splice D2

Extensively tested in SM18 in 2009:-1000 cycles from 50A to 9 kA (5 TeV eq.) @ 50A/s-10 hours @ 9kA-6 provoked quenches @ 9 kA-Thermal cycle to RT-Training up to 11850A-500 cycles from 5kA to 11.85 kA (Nom)-10 hours @ 11.85kA-5 provoked quenches @ 11.85 kA-Training up to 12.85 kA (Ultimate) in 2 natural quenchesNo change of the splice resistance even after

this extensive fatigue test in SM18To be analysed in the LHC machine in

details24th of January 2011

27/23J.Ph. Tock

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