technology department second lhc splices review review of actions from last review list of...

Technology Department

Review of actions from last review Second LHC Splice Review

Second LHC Splices Review

Review of actions from last review• List of recommendations of the first review• Status• Category

A. Various B. Design of main splices consolidationC. Validation/Verification of main splices consolidationD. Management (Schedule, resources)

• Conclusions

29th of November 2011

1/28J.Ph. Tock



Review of actions from last review


Report form the first LHC Splices Review: “Although the design is well beyond the conceptual stage, it is not yet a final design, and this review cannot be considered a final design review. Therefore, although the conceptual design appears to be good, the committee cannot fully assess the soundness of the design until it is final. Another review, when the design is final, or nearly so, may be advised.”

On-going

Various

2/28J.Ph. Tock




II.2 4) p5/14 :Make necessary changes so that ground current monitors are installed on all lower current circuits. These ground current signals should be included in the control system to be logged and to be alarmed when above a pre-set level. The alarm level should be substantially below the power supply hardware interlock for high ground current.

uAmp level was targeted To be studied at QPS (level): See next presentation: R Schmidt [TE-MPE] To be studied at PC level (See next slide: Courtesy V Montabonet [TE-EPC] Splices Task Force 27.10 : https://espace.cern.ch/lhcsplices/Meeting%2051/default.aspx

Review of actions from last review: Ground current monitor (TE-EPC)

Various

3/28J.Ph. Tock

https://espace.cern.ch/lhcsplices/Meeting%2051/default.aspx





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net Earthing of the LHC circuits are defined by

an Engineering Specification : ‘Earthing of the LHC DC Electrical Circuits’ LHC-D-ES-0001 EDMS N°309372

Earthing of the LHC circuits has 4 roles earthing of the circuits for safety reasons: the

load can not be floating,

detection of an earth fault,

limitation of the earth current in case of an earth fault to avoid damaging the circuit elements (mainly instrumentation),

monitoring of the leakage current.

Used for the superconducting magnet circuits

Various

4/28J.Ph. Tock

https://edms.cern.ch/file/309372/2.0/lhc-d-es-0001-20-00.pdf







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RB earth leakage current during precycle

RB earth leakage current at 3.5 TeV

Other circuits :LHC600A-10V

Common Mode = 10V (- neg polarity)

Fuse 1A

Various

5/28J.Ph. Tock




Conclusions


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Actual LHC earthing circuit role is earthing of the circuits for safety reasons: the load can not be

floating, detection of an earth fault, [‖Iearth‖ > 50 mA] limitation of the earth current in case of an earth fault to avoid

damaging the circuit elements (mainly instrumentation), monitoring of the leakage current without any accuracy,

especially around 0mA. The earth leakage current is the LHC circuits is not well-

known and can come from several systems connected to the DC parts.The uAmp level is not reasonably achievable; the 1-10 mA level could be targeted

No automatic analysis tool on possible drift or a warning except the 50 mA thresholdThis could be studied but no action is on-goingELQA checks the earth current yearly with an accpetance threshold of 1 to 50 uAmp[20 for RQF/D – 50 for RB]Ground current monitor in QPS will be presented by R Scmidt

Various

6/28J.Ph. Tock



Review of actions from last review: Consolidation requirements


See presentation by P Fessia yesterday: “Specification of the consolidation of the main IC splices”

II.3 Com3 p6/14:We cannot assess whether or not the shunt meets the requirements, since clearrequirements were not set (or at least not presented to us).II.3 Rec2 p7/14:Develop and document a clear set of requirements, calculations and tests to validate the design, and a defined list of additional tests and criteria against which tests can be evaluated.

Design of main splices consolidation

7/28J.Ph. Tock



Review of actions from last review: Double shunt on quadrupole busbars (1/2)


See presentation by F Savary yesterday: “The consolidated 'shunt' design”Thanks to delay of the LS1, this recommendation was actively pursued (6 months) in order to reach a final informed decision. [TF 29/06/2010]Several options for a second MQ shunt were studied, including their feasibility and consequences. Among all these, the external soldered side shunt was the most feasible. However even this option results in several negative consequences:

A soldering operation that becomes strongly operator dependentA degradation on the soldering quality of the main shuntA loss in precision of the Quality Control process in its current baseline

In addition the expected “redundancy” of this second shunt is extremely limited (no copper surfacing, simultaneous soldering process with the main shunt).In comparison to the MB situation, the margin of safety of soldered surface is larger for the MQ situation.In conclusion, TF recommended to have a single main shunt for MQ and two shunts for MB (per each splice extremity).

II.3 Rec1 p7/14:The Committee recommends that a double shunt be applied to the quad bus.


8/28J.Ph. Tock



Review of actions from last review: Double shunt on quadrupole busbars (2/2)


Examples of studied configurations:


9/28J.Ph. Tock



Review of actions from last review: Clamping system


See presentation “The consolidated electrical insulation” H Prin yesterday

II.3 Rec6 p8/14:Continue the development of the design for a clamp that would hold together the shunt and splice in the absence of solder, to help limit the damage during the time of an energy extraction, and implement the chosen design.


10/28J.Ph. Tock



Review of actions from last review: Industrialisation


II.4 1) p9/14:The Splice Task Force needs to work on improving the manufacturing procedures and the tooling in such a way these are reproducible and not depending on the individuals doing the work. This includes developing adequate QC plans. The review committee recognized the fact that, at this stage of the consolidation programme, this is more important than working out a detailed schedule.

On-goingThis review !

Your comments are welcome


11/28J.Ph. Tock



Review of actions from last review: Radiation protection


II.5 2) p11/14:Radiation safety issues related to the splice repair work should be evaluated and considered in any decision to extend the current run.

See presentations by C Adorisio yesterdayAnd task force meetings 35 & 55, Chamonix

2011


12/28J.Ph. Tock



Review of actions from last review: Lead containing solder


II.5 3) p11/14:The Splices Task Force should consider the potential hazards for workers associated to the utilization of lead-containing solder, and work with the Safety Commission to plan the work to minimize or eliminate this risk.

See presentation by F Savary yesterdayDSO informed


13/28J.Ph. Tock



Review of actions from last review: Cold test results


Report was sent to the reviewers beforehand

II.3 Com2 p6/14:The Committee finds results from high current shunt testing between FRESCA and SM18 confusing. Modelling of all test cases should be documented and qualified based on experimental data, and then applied to the shunt design with worst case assumptions.

Done

Validation/verification of main splices consolidation

14/28J.Ph. Tock



Review of actions from last review: Splices lifetime validation ?


See presentation by Z Charifoulline this afternoon: “Long term evolution of main splices resistance” in the LHC

II.3 Com7 p6/14:Simulations or laboratory tests to verify the lifetime of the old splice against fatigue failure of that solder joint were not presented or discussed. This would need to be done on the old splice and to be repeated for the new design with shunt(s) applied.


15/28J.Ph. Tock



Review of actions from last review: Multiple samples / trials


Extensive tests already done and further tests are planned in the qualification of procedures, tooling and operators (See previous presentations: F Savary & C Scheuerlein)

II.3 Rec3 p7/14:Make multiple samples/trials of critical steps, as part of a qualification plan to bedeveloped, to get a statistically significant basis for assessing the risks of there beingany important imperfections in the machine after installation


16/28J.Ph. Tock



Review of actions from last review: Mechanical calculations


Extensive calculations were done, presented at the task force

II.3 Rec4 p8/14:Make mechanical calculations for the shunt design and the insulating part (3D stressanalysis including fatigue and thermal stresses) and document them to support the finaldesign. All the new model calculations need to incorporate shunts in the most severeconditions assumptions (for example no mechanical connections internal to the originalsplice due to the lack of soldering).

https://espace.cern.ch/lhcsplices/Meeting%2042/default.aspx


17/28J.Ph. Tock



Review of actions from last review: Mechanical tests (some up to rupture)


Extensive tests were carried out, results have been presented at the task force

II.3 Rec5 p8/14:Utilizing representative sample joints in the laboratory, test the mechanical strength ofthe shunt assembly by various stress and deflection measurements, under static andfatigue conditions, both warm and cold. Test several samples to destruction todetermine the limits of the design.


18/28J.Ph. Tock



Review of actions from last review: Visual inspection


II.4 6) p10/14:The Review Committee recommends the Splices Task Force to consider visual inspection as part of the standard QC plan. This does not necessarily need to be done by a specific QC team as it can easily be done by the operators themselves, at least by their supervisors or team leaders. The Review Committee also recommends a systematic documenting by photos

On-goingSee presentations by C Scheuerlein & F SavaryWork is on-going to define a user-friendly web

interface for the data repository

To be finalised for review 3


19/28J.Ph. Tock



Review of actions from last review: Mechanical test


II.4 7) p10/14:The Review Committee recommends also to consider simple mechanical tests applying minimal stress to the joint, as part of the standard QC plan, to check the mechanical continuity of the splices.

See presentations by C Scheuerlein & F SavaryMechanical (destructive) tests done off-line in

laboratory



20/28J.Ph. Tock



Review of actions from last review: Tooling validation


II.6 2) p12/14:The Splices Task Force should draw out a work plan for redesigning and optimizing the various tooling needed for the consolidation activities. These tooling should bevalidated on the surface simulating as real working conditions as possible (e.g. spaceconstraints).See presentation by F Savary yesterday

On-goingTo be finalised for review 3


21/28J.Ph. Tock



Review of actions from last review: Calibration plan for tooling


II.5 4) p11/14:A verification and calibration plan for the special tooling should be drawn up andimplemented to assure a constant quality of the work throughout the production..

See presentation by F Savary & C Scheuerlein yesterday

On-goingQA/QC aspects


22/28J.Ph. Tock



Review of actions from last review: Technicians Qualification


II.6 4) p12/14:At least for the critical operations, the technicians and mechanics should be qualifiedfollowing a strict qualification process similar to what is done for the welding operations (qualification of the process that is to be done once and qualification of each technician/mechanics for each critical operation he is going to carry out).See presentations by F Savary & C Scheuerlein

yesterdayOn-going



23/28J.Ph. Tock



Review of actions from last review: Scheduling


II.4 2) p9/14:It is necessary to have a preliminary work plan with its associated schedule and WBS.II.4 3) p9/14:It would be advantageous for the Splice Task Force to work with an experienced/professional planner/scheduler. The planning needs to be integrated with the planningfor other work that will be done in the tunnel during the same shutdown.II.5 1) p11/14:Continue to review plans to ensure that the work planning is complete.

On-goingSee presentation by F Savary, K Foraz, JPh Tock


Management

24/28J.Ph. Tock



Review of actions from last review: Resources


II.4 4) p9/14:The planning needs to take account of the possibility of unforeseen developments that will slow down or disrupt the orderly work flow. For example, a larger number of splices than the currently estimated 15% may be required to be remade, or problems with the machining of the copper stabilizer could arise. Include schedule contingency into the baseline and ensure that additional resources are available to able to maintain the schedule

II.4 5) p9/14:The Splices Task Force (or CERN more generally speaking) should not repeat the experience of the installation of the splices, i.e. qualified and experienced technicians and mechanics should be identified within CERN including departments/groups other than the MSC Group. The Review Committee is aware of ongoing discussions in this respect but this measure should be given (very) high priority. In addition, the people new to this job should be integrated to the Splices Task Force as soon as possible so that they can be trained to the specific activities constituting the scope of the consolidation plan.

On-goingSee presentation by JPh TockTo be finalised for review 3

Management

25/28J.Ph. Tock



Review of actions from last review: Resources management


II.6 1) p12/14:Study alternate scenarios in view of optimizing the utilization of the critical resources that will certainly be limited (in terms of qualification and experience). Study unforeseen/unexpected scenarios.

II.6 3) p12/14:It is clear to the Review Committee that utilizing contract labour people is inevitable.However the work should be organized in such a way these contract labour people are not left working on their own in the tunnel but are accompanied and supervised byCERN staff of which one can expect the necessary commitment to assure the objective of 100% quality. In other words, CERN needs to keep the full responsibility of the work(this cannot be given to a contractor).See presentation by JPh Tock yesterday

On-goingExperienced resources are limited and focused on the critical activities (Electrical connections, Special Interventions). Mixed team of internal resources, FSU, collaborations

Management

26/28J.Ph. Tock



Review of actions from last review: Resources management


II.7 1) p13/14:CERN should insure that enough resources are allocated to ensure that the risk assessment and subsequent risk analysis can be executed on the planned time scale.

See presentations by H ten Kate and next one by

R Schmidt today

Comment on further needs

Management

27/28J.Ph. Tock



Review of actions from last review: Conclusions


All recommendations have been studied and Implemented orAmended orAre under implementation

With the LS1 rescheduling, deadlines have been updated Review 3 will be a Production Readiness Review

Priority ? Criticality ? What do you consider still open ?

Many thanks to …

28/28J.Ph. Tock




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30/28J.Ph. Tock

Spare slides




31/28J.Ph. Tock

technology department second lhc splices review review of actions from last review list of...

Documents

final design review

lhc splice review report

earth current

review list of recommendations

lhc circuits

lower current circuits

high ground current

ground current monitors