Reinforcement of the LHC Dipole Diodes Insulation during LS2 J.Ph. Tock (TE-MSC) 26.09.2017

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 ? 26.09.2017

Why ? 26.09.2017 Courtesy M Bednarek

Why ? 26.09.2017

Why ? 26.09.2017 Courtesy M Bednarek

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 Todesco@Chamonix] 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 (2019-20) 26.09.2017 Based on a presentation of A Verweij

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. 26.09.2017

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 26.09.2017

Installed on 15% of the cryodipoles Insulating half moon pieces Why ? Installed on 15% of the cryodipoles 26.09.2017

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. 26.09.2017 Based on a presentation of C Scheuerlein

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 26.09.2017 Based on a presentation of C Scheuerlein

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 26.09.2017

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 26.09.2017

Based on a presentation of C Scheuerlein Conceptual technical solution How ? 3. Remove the (metal) debris in the accessible areas 26.09.2017 Based on a presentation of C Scheuerlein

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 26.09.2017

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 26.09.2017

How ? Coordination tool J Pereira Lopes 26.09.2017

When ? OPEN IC ≈ 1 year ≈ 1.5 year CONSOLIDATE RECLOSE IC AND LT NC SOLVING 26.09.2017

When ? End after 52 weeks (without margin) Start reclosure First sector finished (7 months) 26.09.2017

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

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 26.09.2017

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) 2017-02-06 Defending LHC dipole diodes #3 – Indico 616383 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 26.09.2017

TE-MPE 26.09.2017

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 26.09.2017

EN-MME : Cutting and re-welding 26.09.2017

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) 10-12 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 26.09.2017

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 26.09.2017

First internal LHC Dipole Diodes Insulation Consolidation Review Organisation Week 40 : Rehearsal 6.10.2017 : First version of presentations uploaded in Indico Tuesday 10.10.2017 : Technical presentations Wednesday 11.10.2017 : Visit of workshop, mock-ups,…. Organisation / resources (Restricted session) Time for additional presentations Time for reviewers Thursday 12.10.2017 Timer for reviewers Close-out Week 48 : Report from the committee With the support of S Sapountzi 26.09.2017

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 26.09.2017

First internal LHC Dipole Diodes Insulation Consolidation Review 26.09.2017

First internal LHC Dipole Diodes Insulation Consolidation Review 26.09.2017

? AOB Project meetings organisation Every two weeks to start, At the beginning, focus on the review with ad-hoc meetings And a rehearsal on 6.10.2017 (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 ? 26.09.2017

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) 26.09.2017

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 26.09.2017

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 26.09.2017 Based on a presentation of L Grand-Clement

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 26.09.2017

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 26.09.2017

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 2017-02-06 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,…] 26.09.2017

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 26.09.2017 Courtesy M Bernardini

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 26.09.2017 Based on a presentation of L Grand-Clement

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) 26.09.2017 Based on a presentation of S Le Naour

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 26.09.2017 Based on a presentation of S Le Naour