Jaime Perez Espinos on behalf of all contributors to LHC insulation vacuum (TE/VSC, AL4030 and ICIT)

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2 OLAV IV Jaime Perez Espinos on behalf of all contributors to LHC insulation vacuum (TE/VSC, AL4030 and ICIT)

3 Contents Before LS1 Introduction to LS1 LHC insulation vacuum system overview LS1 activities for insulation vacuum (IV) IV consolidation: safety issues and improvements Status and follow-up of leaks in IV Examples of leaks (LS1) Summary 9 April 2014 Jaime Perez Espinos 3

4 Before LS1 More than 3 years of successful operation of LHC and its vacuum system Insulation vacuum during LHC operation: Very good performance No shutdown or beam stop due to any problem coming from IV 9 April 2014 Jaime Perez Espinos 4

5 Introduction to LS1 LS1: ~ 2 years stop beam to beam Objective: Bring all necessary equipment up to the level needed for 7TeV/beam Main priorities of LS1 for LHC: Activities linked to incident Sept. 2008: Consolidation of 13 ka supeconducting splices and repair of defectuous interconnects (powering at 7 TeV) Installation of remaining pressure relief devices DN200 Repair of known He leaks (especially 2 in sectors 3-4 and 4-5) Others (related to IV): IV and cold BV consolidation Maintenance 9 April 2014 Jaime Perez Espinos 5

6 A6R7 A8L8 A5L8 A4L8 DFBM Q6R7 DFBAN Q31R7 Q32R7 DFBAO Q6L8 DFBM Q5L8 DFBM Q4D2_L D1L8 DFBX LHC IV system overview QRL (cryogenic distribution line) Inner triplet Matching section Dispersion supressor Arc Dispersion supressor Matching section Inner triplet I H G F E D C B A S. 7-8 Q7R7 Q10R7 Q11R7 Q14R7 Q15R7 Q18R7 Q19R7 Q22R7 Q23R7 Q26R7 Q27R7 Q30R7 Q33R7 Q32L8 Q31L8 Q28L8 Q27L8 Q24L8 Q23L8 Q20L8 Q19L8 Q16L8 Q15L8 Q12L8 Q11L8 Q7L8 Q3L8 Q1L8 A7R7 A11R7 A15R7 A19R7 A23R7 A27R7 A31R7 A31L8 A27L8 A23L8 A19L8 A15L8 A11L8 A7L8 A1L8 QRL IV subsector (9 per sector / TOTAL 72) CONTINUOUS ARC CRYOSTAT Stand alone cryostat (TOTAL 50) Magnet IV subsector (14 per sector / TOTAL 112) Beam vacuum for beam lines 9 April 2014 Jaime Perez Espinos 6

7 LHC IV instrumentation layout QRL vacuum subsector (428 m) QRL LINE Vacuum barriers CONTINUOUS ARC CRYOSTAT Vacuum subsector (214 m) BEAM LINES 4 series of 1 quadrupole + 3 dipoles 9 April 2014 Jaime Perez Espinos 7

8 VENT BV RF BALL PUMP & LT BV LEAK TEST (1) >80K; (2) 5 bar VENT IV PUMP IV LT (PRESS. TEST) LS1 activities for IV Leak test support Splice consolidation Special interventions Cryomagnets, connection cryostats, diodes, Y lines, triplet braids DFBA Splices and flexibles Localisation of known leaks IV consolidation Final safety valve configuration Flap valves and spring loaded valves Improvements New by-passes, turbos, p/o ports Maintenance Pumps, O-ring exchange PIMs Cold BV consolidation New protection devices Interconnection QC Protective shells; rupture disks and non-return valves Integrity of bellows 9 April 2014 Jaime Perez Espinos 8

9 Vac enclosure P [bar] Vac enclosure P [bar] IV consolidation safety issues Safety valve configuration New protection scheme based on redefinition of Maximum Credible Incident (MCI) Nominal operation: max. flow of 30 Kg/s at 90K Protection of the LHC insulation vacuum enclosure against He overpressure Powering phase I (access authorized): max. flow of 1 Kg/s at 90K Protection of the LHC insulation vacuum enclosure against He overpressure Protection of personnel against He relief Configuration Sept 2008: 2 DN90 Protection on consolidated subsectors: 12 DN200, 2 DN kg/s 20 kg/s DP 2 kg/s Vac enclosure He T [K] DP 40 kg/s 20 kg/s 2 kg/s Vac enclosure He T [K] (DP: Design Pressure) 9 April 2014 Jaime Perez Espinos 9

10 IV consolidation - improvements LHC vacuum instrumentation before incident in 2008 LHC vacuum instrumentation after LS1 Spring loaded valve with p/o port By-pass New p/o port Self closing valve Spring loaded valves 9 April 2014 Jaime Perez Espinos 10

11 LS1: summary of main activities so far Consolidation activities: IV: ~3,800 mechanical interventions Cold BV: ~1,000 mechanical interventions Inspections (bellows, flexibles ): ~15,000 Maintenance: IV: ~300 vacuum pumps (130 turbos) Leak tests: Support clamshell leak tests: ~5,600 Global leak tests: Envelope: ~330 Internal (He lines): ~230 9 April 2014 Jaime Perez Espinos 11

12 Leaks follow-up in IV MAGNET + QRL More demanding for acceptance LS1 leaks identified before start of consolidation activities, so not linked to them Remaining leaks = leaks open for actions or leaks repaired but not leak tested goal: no leaks at start of operation Acceptable leak levels during LS1 more demanding than during installation phase All leaks correspond to IV. No leaks present in cold BV 9 April 2014 Jaime Perez Espinos 12

13 Status of leaks and NCs in IV Leak tests linked to consolidation activities have been done for 6 out 8 sectors Inspection procedures linked to consolidation activities have been done for 7 out of 8 sectors Good 9 April 2014 Jaime Perez Espinos 13

14 Known leak: s. 3-4 With 2 additional turbos, equilibrium pressure was ~ 7e-4 mbar max (Q28) ~ 5e-5 mbar at turbos Q31L4 Vac Barrier Subsector A27L4.M Q30L4 Q29L4 214 metres Q28L4 pressure gauge Q27L4 Vac Barrier 9.3 E-5 mbar 1.1 E-4 mbar (+18%) 1.21 E-4 mbar (+31%) permanent turbo pump additional turbo pump additional turbo pump 9 April 2014 Jaime Perez Espinos 14

15 Known leak: s. 3-4 SOLVED! Bad decision in repair strategy!!! Leak location (inner surface; before cutting) Details: crack, lack of fusion, segregation, cold drops Detail inner surface: Porosity 9 April 2014 Jaime Perez Espinos 15

16 Known leak: s. 4-5 QRL, lines C & D (internal leak) Virtual leak SOLVED! Failure process: filling of the inter-layer space with time (3-4 years of operation) Pressure increase of the inter-layer space during warm-up leading to the compensator collapse Compensator damaged: DN100 multiply (4 plies of 0.3 mm) 9 April 2014 Jaime Perez Espinos 16

17 Leaks during LS1: example #1 k flexibles (internal leak) SHOCK FATIGUE CRACK k flexibles exposed to mechanical activities in interconnections need for improvement of mechanical interventions and quality control? 9 April 2014 Jaime Perez Espinos 17

18 Leaks during LS1: example #2 Leaks on feet (external leak; 2 types) Type 1: continuous weld Pump-out of volume in-between Type 2: non continuous weld Vacuum weld No accessibility to vacuum weld pump-out or isolate space between enclosure and support structure 9 April 2014 Jaime Perez Espinos 18

19 Other leaks k collector k flexible M/N flexible Jumper (weld/material) W bellows (flat seal) Connector feedthrough 9 April 2014 Jaime Perez Espinos 19

20 Summary Consolidation activites are ongoing and with good timing Quality of final product has improved and leaks decreased Right leak test methodology has led to identification of all leaks; many of them already solved LS1 is allowing to deepen, even more, in machine knowledge and leak types 9 April 2014 Jaime Perez Espinos 20

21 Thanks 9 April 2014 Jaime Perez Espinos 21