2. Reinforcement of the LHC Dipole Diodes Insulation during LS2
J.Ph. Tock (TE-MSC)

3. First internal LHC Dipole Diodes Insulation Consolidation Review
Scope of the project
Why ?
How ?
When ? / Planning
Who ? / What ?
First internal LHC Dipole Diodes Insulation Consolidation Review
AOB
Project meeting slot
Project name
Summary / Questions ?

4. Why ?
Courtesy M Bednarek

5. Why ?

6. Why ?
Courtesy M Bednarek

7. Based on a presentation of A Verweij
Risk analysis in a nutshell
Why ?
Probability of O(1%) [2/254* quench events since 2014] to have a single short to ground per quench event at high current
Probability of O (0.01%) to have a double short to ground dissipating sufficient energy to melt a hole in the helium enclosure
O(500) training quenches required to reach 7 TeV [E
2 shorts at cold were solved using the EFB.
Reliability ?
Time taken ?
Risk ?
Non-negligible O (5%) (non-acceptable?) probability to have a double short to ground with major consequences
*including the 2 training quenches in S12 for the recommissioning in 2017
Study the possibility to reinforce the (dipole) diodes insulation during LS2 ( )
Based on a presentation of A Verweij

8. CMAC Recommendation Why ?
Perform a quantitative risk analysis of the impact of potential problems caused by magnet training [and operation] and develop a mitigation plan. Study the possibility to (remove debris in all magnets, to clean and) better insulate the diode boxes and establish the necessary time and resources required to do it.

9. Priorities during LS2 P0 : Safety
P1 : Activities needed to reach 300fb-1 during run 3
P2 : HL-LHC & LIU projects
P3 : Approved projects
P3A: Approved project if budgeted*
P4 : Approved studies
P5 : Others

10. Installed on 15% of the cryodipoles
Insulating half moon pieces
Why ?
Installed on 15% of the cryodipoles

11. Based on a presentation of C Scheuerlein
Conceptual technical solution
How ?
For the ≈ 1050 cryodipoles where insulating half moons are not installed
 Install optimised half moon insulating pieces where they are missing
100 pairs of modified insulating plates made of EPGM203 epoxy glassmat have been procured.
Based on a presentation of C Scheuerlein

12. For the ≈ 180 cryodipoles where insulating half moons are installed
Conceptual technical solution
How ?
For the ≈ 180 cryodipoles where insulating half moons are installed
Studies are on-going to possibly improve existing insulation
Collateral risks need to be evaluated
Not installing extra components is an option
The review outcome will be helpful
Based on a presentation of C Scheuerlein

13. Based on a presentation of C Scheuerlein
Conceptual technical solution
How ?
2. Reinforce the electrical insulation:
In the diode container (bare bus bars)
We propose to add an easily mountable single electrically insulating piece that covers the busbars
No major impact of the insulation piece on the cryogenics system is expected, provided that the free cross sections in the insulation piece through which He can flow are at least as large as the free cross sections in the diode.
The mechanical properties of the insulation piece and its fixation should guarantee that He pressure fluctuations do not disintegrate the piece or detach it from its geometrical position.
3D printout of a prototype busbar insulation piece. Courtesy T. Sahner.
Based on a presentation of C Scheuerlein

14. Based on a presentation of C Scheuerlein
Conceptual technical solution
How ?
2. Reinforce the electrical insulation:
In the diode container (bare bus bars)
Screwing the insulation to the diode avoids any stresses on the busbars and half moon splice, and it guarantees a proper alignment of the insulation with respect to the busbars.
Threaded holes to which the insulation piece can be fixed.
Sketch of insulation piece that can be screwed to the diode.
Based on a presentation of C Scheuerlein

15. Based on a presentation of C Scheuerlein
Conceptual technical solution
How ?
3. Remove the (metal) debris in the accessible areas
Based on a presentation of C Scheuerlein

16. Conceptual technical solution
How ?
The half moon connections have been checked during LS1:
Locally at warm (ElQA)
Globally at cold (CSCM)
The consolidation activities should not require to disconnect the half moon connections
It should be sufficiently non-invasive to avoid stressing this connection
Warm resistance of the diodes leads will be checked before and after consolidation (ElQA)
 No CSCM needed for the dipole circuit at the end of LS2

17. How ? No intervention on quadrupole diodes
10 diodes consolidated per day [15 openings or 12 reclosures per day]
1 sector opened in 2 weeks, reclosed in 3 weeks
1. Open outer bellows and thermal shields
2. Give access to the diodes busbars (Mechanical cutting)
3. Local ElQA before intervention
4. Clean the diode box and cold mass extremity
OPEN IC
CONSOLIDATE including QA & QC
5. Consolidate electro-mechanical insulation
6. QA/QC of the consolidated insulation
7. Reclose cold mass volume (Welding)
8. Local ElQA after intervention
CONSOLIDATE including QA & QC
9. Intermediate leak test
(Clam shell [TBC])
10. Reclose interconnections
11. Final leak test
CONSOLIDATE & QA/QC
RECLOSE IC AND LT

18. How ?
Coordination tool
J Pereira Lopes

19. When ? OPEN IC ≈ 1 year ≈ 1.5 year CONSOLIDATE RECLOSE IC AND LT
NC SOLVING

20. When ? End after 52 weeks (without margin) Start reclosure
First sector finished (7 months)

21. When ? Courtesy M Bernardini 26.09.2017 (Almost) no co-activity

22. Working times When ? Access limitations
BLM removal and reinstallation
Opening and reclosure of IC
Cutting and rewelding of diodes container
Insulation consolidation QC
Leak tests
Replacement of cryomagnets
Special interventions
Non conformities
Preparation for
ELQA
HV ELQA
Twice per week
Transport
and RX
Sometimes more than 100 persons in the same sector: problem of coactivity
Interference with the transport: exceptionally need to remove the
voluminous material from the passage

23. Who ? Long Shutdown 2 JM. Jimenez
J.Ph. Tock # ≈ 150 Interventions on LHC SC magnets ( Diodes consolidation)
Deputies
L Van Den Boogaard, M Pojer
Project Leader’s Office #8
M Bernardini, S Le Naour, T Otto, M Pojer, L Van Den Boogaard,…….
Radiation protection
Safety, Access
General logistics
Pressure test
Link to visits, media
Coordination with Survey, Instrumentation, Transport, planning, QPS, VSC, MPE, CRG, … Test teams on a chain of IC
Reporting tools
Administrative support (Budget, human resources, scientific secretary)
Defending LHC dipole diodes #3 – Indico J.Ph. Tock 23
Open/Close IC
#25
L Van Den Boogaard
Diodes cons. #20
Quality Assurance
# 26
M Pojer
A Devred
LARGE SUPPORT FROM BE-OP
Opening/ Closure of IC W bellows & ther. shields
Cleaning
Consolidation
Experts
Electrical QC: # 12
-Welding QC: # 3
ICIT: : # 6
QA manager support: #2
Audits: #2
BLM [BE-BI]
# 7
C Zamantas
Removal and reinstallation of BLM and their cable trays
Special interventions “SIT” #18
HL-LHC (CC/11T)
Cryomagnets exchange
PIMs
Specific issues
Heavy NCs
ELQA [TE-MPE]
#21
Continuity
HV test
Leak Test [TE-VSC]
#15
Beam lines
Cryogenics lines
Insulation vacuum
Cutting&Welding [EN-MME] #13
? / ?
? / ?
G Favre
- Opening
- Rewelding

24. TE-MPE

25. TE-VSC 7. Diode test [ElQA] Local leak tests (TBC) Global leak tests
1. Open outer bellows and thermal shields
2. Give access to the diodes busbars (Mechanical cutting)
3. Clean the diode box and cold mass extremity
4. Consolidate electro-mechanical insulation
5. QA/QC of the consolidated insulation
6. Reclose cold mass volume (Welding)
7. Diode test [ElQA]
8. Intermediate leak test
(Clam shell [TBC])
9. Reclose interconnections
10. Final leak test
Local leak tests (TBC)
Global leak tests

26. EN-MME : Cutting and re-welding

27. First internal LHC Dipole Diodes Insulation Consolidation Review
Scope
the consolidation of the electrical insulation of the LHC dipole diodes
Series of review
Design and preliminary readiness INTERNAL review (see later) October 2017
INTERNATIONAL Project Readiness review Mid 2018 To assess :
the final design for the consolidation of LHC dipole diodes insulation and especially if recommendations from the review 1 have been correctly integrated
if no other simultaneous consolidation is forgotten
the production and quality control procedures
the work organization, quality control, resources, schedules
the readiness for the shutdown intervention: specifications, procedures, quality control
methodologies, qualifications, resources, schedule
compatibility with other planned activities (e.g. LIU and HL-LHC)
INTERNATIONAL Quality Audit Summer 2019 To assess :
if the encountered situation corresponds to the expectations and assumptions used during the preparation of the project
if the implementation corresponds to the plan, especially in terms of Safety, Quality and Schedule

28. First (internal) review : Design and preliminary readiness review
First internal LHC Dipole Diodes Insulation Consolidation Review
First (internal) review : Design and preliminary readiness review
To assess :
If the need for consolidation is clear
If the requirements (functional specification) to be filled are clear and complete
If the proposed solution is answering the needs
If the proposed solution is compatible with the LHC operation requirement and does not present a collateral risk
if all interfaces and neighbouring systems have been considered
(If no other consolidation could profit form the access given and so can be carried out in the same time window)
If the preliminary plans are sufficiently sound and developed to have a safe and validated solution implemented in the available on time, including tooling, training, mock-ups, personnel and competences build-up

29. First internal LHC Dipole Diodes Insulation Consolidation Review
Organisation
Week 40 : Rehearsal
: First version of presentations uploaded in Indico
Tuesday :
Technical presentations
Wednesday :
Visit of workshop, mock-ups,….
Organisation / resources (Restricted session)
Time for additional presentations
Time for reviewers
Thursday
Timer for reviewers
Close-out
Week 48 : Report from the committee
With the support of S Sapountzi

30. First internal LHC Dipole Diodes Insulation Consolidation Review
Committee
Arnaud Devred / CERN TE-MSC Chair :
Laurent Tavian / CERN ATS-DO
Roberto Lopez / CERN TE-MSC
Francesco Bertinelli / CERN EN-MME 
Felix Rodriguez-Mateos / CERN TE-MPE
Alain Poncet / CERN retiree

31. First internal LHC Dipole Diodes Insulation Consolidation Review

32. First internal LHC Dipole Diodes Insulation Consolidation Review

33. ? AOB Project meetings organisation Every two weeks to start,
At the beginning, focus on the review with ad-hoc meetings
And a rehearsal on (10:30 ? 14:00)
3 slides : Outline, conclusions, open points
Meeting room to be announced
Frequency will be adapted according to the needs (// coordination meetings)
Time slot : (doodle)
Tuesday 10:30
Tuesday 16:00
Wednesday 10:30
Thursday 9:00
Thursday 14:00
Friday 14:30 ?
Project NAME ?

34. Summary
The consolidation of the LHC dipole diodes insulation is required before training campaigns to go to 7 TeV
A technical solution consisting in :
Installing optimised half moon insulating pieces
Reinforcing the present insulation
Removing the accessible metal debris
is under development
An in-work organisation chart for the project is proposed
The integration in the LS2 schedule is achievable
This is a CERN wide project, that can only be achieved with support from other groups (As SMACC during LS1)

36. Why ? Previous short circuits in dipole diode containers
9 (TBC) shorts to ground in dipole diode containers since June 2006
No correlation with sector or magnet manufacturer

37. Based on a presentation of L Grand-Clement
Quadrupole diodes
All quadrupole diodes have been consolidated during LS1
Much less debris than in the dipole containers
All were cleaned during LS1
All NCs (from assembly) have been corrected during LS1
Worst cases
< 10 / 392
Quadrupole diodes insulation is as robust as dipole ones after the proposed consolidation
No need to intervene on the quadrupole diodes
No CSCM needed for quadrupoles during LS2
Based on a presentation of L Grand-Clement

38. Quadrupole diodes Comparison with main dipole circuits :
No short circuit in quadrupole diodes containers (so far)
About 1/3 of magnets (wrt dipole magnets)
Energy stored : 25 MJ (<< 1350 MJ for the dipoles) [2%]
Time constant : much lower ≈ 33 s (< ≈ 105 s for the dipoles)
Much less quenches for training and during operation
Risk analysis (To be finalised)
Lower probability
Smaller severity
Hydraulic configuration is favourable (less risk to have debris transported to the quad diode container)
 back-up slide
Better insulated than the dipole diodes

39. Budgeting assumptions
How much ?
6 efficient working hours per day
4 non working weeks
1 sector opened in 2 weeks, reclosed in 3 weeks
5.5 hours [Longest single operation] to consolidate one diode (depending on solution) / (10% margin – small NCs)
10 diodes consolidated per working day [All operations]
SIT : same as SMACC
BE-OP support, especially for ElQC but not only
3 weeks for learning
3 months for NC solving (SMACC experience)
TOTAL : 18 months
Same type of human resources as SMACC (Staff, collaboration, FSU,…)
Means oriented

40. How much ? Standard LS interventions (including 11T and LEP)
Budget divided in 8 sub activities
Project Leader # 146
Consolidating LHC dipole diodes
Project Leader’s Office #8
Open/Close IC
#25
Diodes cons. #20
Quality Assurance
# 26
Cutting & Welding [EN-MME] #13
Special interventions “SIT” #18
ELQA [TE-MPE]
#21
Leak Test [TE-VSC]
#15 40 40
Standard LS interventions (including 11T and LEP)
Consolidation Of the LHC Dipole Diodes [COLD2]
Only material budget:
M4P [FSU, collaborations, contractors]
M [Tooling, components, logistics,…]

41. Conclusions on LS2 planning for the diodes consolidation
When ?
Conclusions on LS2 planning for the diodes consolidation
The preparation of the LS2 has already started
Dipole diodes consolidation
The activities related to the dipole diodes consolidations fit in the LS2 schedule
The duration of the complete diode consolidation is 51 wks, including the Xmas closure. 3 wks are available at the beginning of the project for learning. Additional time (about 2.5 months) will be available for non conformities resolution, if needed
The project organization should be similar to that implemented during LS1 for splices consolidation (SMACC)
The date of the PZ33 lift replacement should be reviewed, to cope with the dipole diodes consolidation
The impact of the diodes consolidation on the HWC should be defined
The main concern is related to the resources availability during the LS2, to prepare and to not compromise the LHC activities for LS3
Courtesy M Bernardini

42. Based on a presentation of L Grand-Clement
Quadrupole diodes
LHCLQMJS0001
Insulation pieces
Tube 168.3x2.6 He
Helium flows to the diode stack from behind
Most of debris likely blocked by the insulation pieces behind the diode
The insulation sleeve is already in the container unlike MB diode
It insulates all active parts of the diode stack with respect to ground
Based on a presentation of L Grand-Clement

43. Based on a presentation of S Le Naour
Insulating half moon pieces
Why ?
Radiographic inspections done:
During LS1 (W-bellows open)
For the 2 earth faults during training (W bellows closed)
During this EYETS (W bellows closed)
Based on a presentation of S Le Naour

44. Based on a presentation of S Le Naour
Insulating half moon pieces
Why ?
Radiographic inspections allow to check the presence of the protection
About 15 % of the dipole diodes are protected
53 diodes have been analysed
Based on a presentation of S Le Naour