cryomagnets, interconnections, superconducting circuits · 2011. 11. 23. · cryomagnets,...

Technology

Department

Cryomagnets, Interconnections, Superconducting Circuits:

24th of January 2011 Chamonix 2011 LHC Performance Workshop

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

1/23

J.Ph. Tock

Technology

Department


• 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 Chamonix 2011 LHC Performance Workshop


2/23

J.Ph. Tock

Technology

DepartmentContext : The impact of these “special” interventions




Limited space

Shared human resources

Limited time

(Minimise the impact on the shutdown duration)

Interventions on the same circuits

3/23

J.Ph. Tock

Technology

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




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)

4/23

J.Ph. Tock

Technology

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




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 shift

Workload: About 600 man hours per standard cryodipole replacement

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

Less if consecutive magnets

5/23

J.Ph. Tock

Technology

Department


Vacuum related issues (1/3)



Leaks

Subsector is localized but not the exact leak origin

Time is required before opening & during the shutdown for leak detection/localisation

Present status : about 20 leaks / 11 are important / 1 is critical (A27L4)

Usually, repairable in-situ

New leaks could appear before the next long shutdown or be created by the warm-up

Typical 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 situation

Only one cryomagnet could have potentially to be exchanged (A27L4) 6/23

J.Ph. Tock

Technology

Department





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

-Preventive replacements :

+ Arc extremities

18/32 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-up

Conclusion: 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

7/23

J.Ph. Tock

Technology

Department





Nested bellows:About 55 small damages identified / 2 are heavier

Inspection 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 planned

Beam 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 34

This could be an issue for cryogenics and electron cloud build-up

VSC follows that with ABP & CRG

No 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

8/23

J.Ph. Tock

Technology

DepartmentConsolidation of SAM Helium level gauges




Cryogenics related issues (1/3)

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

Existing capillary replaced by a larger metal hose

It is planned to consolidate the 2 remaining ones

(Q6R2, Q6L8) during the long shutdown

Repair of leaking Y-lines

It is planned to consolidate the 2 known cases

(S78:17-19R7 & S81:19-22R8) during the long

shutdown

9/23

J.Ph. Tock

Technology

DepartmentInstallation 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)

10/23

J.Ph. Tock

Technology

Department

Triplets braid





Cryo-InstrumentationAccess will be given to allow

cryo-team to intervene

L1 R1 L2 R2 L5 R5 L8 R8

NCR 982513 982506 982524 982518 982511 982525 982512 982517

Action Remove Install Remove Install Install Remove Remove Install

Stat./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 available11/23

J.Ph. Tock

Technology

Department




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 displacement

Addition of extra insulation to go up to ultimate energy

12/23

J.Ph. Tock

Technology

Department




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

Electr(omenchan)ical integrity (2/4)

Circuit issues (Open, high R)Circuit Sector Remark

RCO.A81B2 81 Circuit is open

RCBH31.R7B1 78 Circuit is too resistive

RCOSX3.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

13/23

J.Ph. Tock

Technology

Department




Cryomagnets issues: High internal splice resistanceElectr(omenchan)ical integrity (3/4)

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 resistance14/23

J.Ph. Tock

To be disconnected for

DS Coll installation

Technology

Department




Cryomagnets issues Electr(omenchan)ical integrity (4/4)

# to exchange (proposal)

+ 5 dipoles

15/23

J.Ph. Tock

Dip ID Sector Issue Status

1007 78 Breakdown at 1.6 kV Diagnostic (IFS) then exchange if not repairable in tunnel

1263 67 IFS wires Inspect then likely repairable in the tunnel


2007 78 QH likely damaged Diagnostic (TDR) then advisable to exchange




2413 12 Weakness in 3 HF QH Advisable to exchange


Has also a high inner splice resistance

Technology

Department


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: Q28,32

Q5L8 : 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)

16/23

J.Ph. Tock

Technology

Department


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 Radially

DFBA to move # 2 Affect also warm region

DS Collimators # 4 TCRYO

New cryostats # 3 1 CC’ of ≈ 9 m length

Jumper longi motion # 4 DFBA & Q7: Not standard

Modif line N # 6 (8)

Involves surface work

17/23

J.Ph. Tock

Technology

Department

Miscellaneous




BPM cables checks and repairs

RP samples : See ECR LHC-LI-EC-0001 for details

Recover and measure some of them ;

New ones to be installed ?

New issues appearing before long shutdown

Detected during operation (Higher L, E, time…)

Non-conformities generated during the long

shutdown

18/23

J.Ph. Tock

Technology

Department

•How many cryomagnets to exchange? Spares?




19/23

J.Ph. Tock

MB SSS Tot

1 8 1 9 High inner splice resistance To be confirmed after tests/study

2 5 0 5 Electrical integrity Between 1 and 9

3 0 2 2 Beam optics Restoration of MQS in 34 only

4 1 0 1 Leaks Depending on repairability

5 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

Technology

DepartmentThe special interventions team




Function At CERN Missing Total WorkCoordinator 0.5 0 0.5 External interfaces

Team leader 1 0 1 On-site

Expert welder 1 1 2 All types of welds

Welder 0 1 1 Assistant

Welders Automatic and manual (including QA,…)

Expert electromechanic 1 0 1 Ultrasonic welds

Electromechanics 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 1.5

ELQA Krakow Collaboration: Not in total

QA 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

Technology

Department

The work location




21/23

J.Ph. Tock

High inner splice

SSS

Highest leak

Electrical integrity issue

Reversed beam screen(s)

Beam opticsDS Coll.

Spread all around : work on leaks, PIMs,

SAM (He, DN160)

Y-lines repairCC Consolidation / InspectionDN 200 installationTriplet braid

Cryo-dipole

Circuit and splices issues

Technology

DepartmentConclusions




22/23

J.Ph. Tock

[FTE] [%]

6.4 32% Cryomagnets Exchange

4.5 23% DS Collimators

4 20% Other planned work

5.1 26% New issues / NC

20 TOTAL

The list of interventions on superconducting magnets and circuits (other than

main splices consolidation) has been presented.

Work is foreseen all along the LHC

A team to carry out these interventions in the allocated time has been

presented; the ratio of experienced staff (<1/3) seems low

The 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

resistance

A value of 30% for new issues & NC seems more realistic

Technology

Department




23/23

J.Ph. Tock

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

Technology

DepartmentSpare slides




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

24/23

J.Ph. Tock

Technology

Department

High internal splices resistances (1/5)

LHC machine and spare status

The cryodipole specification is < 7 nOhm for dipoles

All 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 nOhm

1 [Q7R3] is > 20 nOhm

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

24th of January 2011 Chamonix 2011 LHC Performance Workshop25/23

J.Ph. Tock

Technology

Department


Experience so far3 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


2420:(Spare): R ≈ 25 nOhm Interaperture splice

Pictures from H Prin (MSC-LMF)

Almost no soldering in splices


J.Ph. Tock

Technology

Department


Degradation : Experience so far

Test report EDMS No1008959 : Splice

Resistance measurements in SM18 : 2303

(TE-MSC-TF)


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 quenches

No change of the splice resistance even after this

extensive fatigue test in SM18

To be analysed in the LHC machine in details


J.Ph. Tock

cryomagnets, interconnections, superconducting circuits · 2011. 11. 23. · cryomagnets,...

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