Superconductivity and Cryogenics at CERN!

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1 Superconductivity and Cryogenics at CERN! S. Claudet (CERN, Geneva) LHC Cryogenics Operation With valuable input from L. Tavian & A. Perin for their study on similar topic published March2010, EDMS

2 Abstract Superconductivity and associated cryogenics have been used at CERN since the sixties, with a sharp rise in capacity and size for the LEP200 project and more recently for the LHC. The actual achievements for LHC will be presented, with the emphasis on the approach used towards efficiency and availability. Perspectives for power distribution applications will be proposed, considering operational constraints transposed to long power lines. 2/42

3 Outline Introduction to CERN and LHC Cryogenics Relevant hardware and key performance Operation, maintenance organisation and results so far Perspectives for superconducting power lines Summary 3/42

4 Founded in 1954 CERN in brief European Organization for Nuclear Research 20 Member States + Associates Annual budget:! 900 MCHF Below staff Over users Geneva p-p collisions cm -2.s TeV 0.5 GJ stored energy 24 km of superconducting K, 8.33 T 4/42

5 Overall layout of LHC and its detectors! 100 m Diameter 8.5 km Slope 1.4 % Geological stability and controlled environment 5/42

6 Main reasons to superconducting For accelerators in high energy physics Compactness through higher fields E beam = 0.3. B. r E beam = E. L [Gev] [T] [m] [Gev] [MV/m] [m] Capital Cost Not really the case for power lines Saving energy Operating Cost Electromagnets: Acceleration cavities Resistive: P input! E beam P input! Rs.L.E 2 /w Superconducting: P input! Pref R s! R BCS + R o R BCS! (1/T) exp(-bt c /T) Clear potential for power lines 6/42

Layout of cryogenics Pt 5 Pt 4 Pt 6 Pt 3 8 x 18kW @ 4.5 K 1 800 sc magnets 24 Cryoplant km & 20 Distribution kw @ 1.8 K Present Version 36 000 t @ 1.

7 Layout of cryogenics Pt 5 Pt 4 Pt 6 Pt 3 8 x 4.5 K sc magnets 24 Cryoplant km & 20 Distribution 1.8 K Present Version K 130 t He inventory Pt 7 LHC cryogenics is the largest, the longest and the most complex cryogenic system worldwide Pt 2 Pt 1.8 Cryogenic plant Pt 1 Pt 8 7/42

8 Odd point MP Storage Cryogenic architecture Typical LHC even point Even point MP Storage Odd point MP Storage 1 Refrigerator could keep the helium inventory in place, and allow the operation of LHC at low level 1.8 K Refrigeration Unit Warm Compressor Station Cold Compressor box New Existing 4.5 K 4.5 K Refrigerator Refrigerator Warm Warm Compressor Compressor Station Station Cold Box Upper Cold Box Lower Cold Box Interconnection Box Box 1.8 K Refrigeration Unit Warm Compressor Station Cold Compressor box Surface Shaft Underground Shaft Surface Cavern Distribution Line Magnet Cryostats, DFB, ACS LHC Sector (3.3 km) Distribution Distribution Line Line Magnet Cryostats, DFB, ACS LHC Sector (3.3 km) Tunnel 8/42

9 Evolution of capacity with time Equivalent cooling capacity at 4.5K, delivered by industry LHC, ATLAS, CMS LHC Before LHC: existing experience for design, safety, controls, operation, availability, ITER OMEGA, BEBC, ISR Low-Beta LEP2 ALEPH, DELPHI, LEP Low-Beta LEP LHC: 144 kw Tevatron, RHIC, Jlab, SNS, HERA, Tristan,! Year We did not start from scratch! 9/42

10 Evolution of length with time Length of cryogenic distribution lines LHC 3500 [meters] LEP2 LHC: 25 km CERN made lines From CERN home-made hardware to industry (+ support) for large projects 10/42

11 Evolution of Helium storage with time Necessary Helium inventory to allow operation [tonnes] Virtual Liquid 2 MPa Helium Inventory 50 0 Tevatron HERA CEBAF RHIC LEP2 LHC (SSC) Losses of about 2% per month to be compensated 11/42

12 Outline Introduction to CERN and LHC Cryogenics Relevant hardware and key performance Operation, maintenance organisation and results so far Perspectives for superconducting power lines Summary 12/42

13 Testing the cryogenic sub-systems Performance assessment of all sub-system (at least a type test) before being connected to the next one Point 8 Storage QSCC QSCA QSRA QSCB QSRB QSCC Shaft Surface QURA QURC QUIC QURC Cavern Sector 7-8 Sector 8-1 Large impact of discussions with manufacturers for HW protection settings: they want to protect, we want to operate Tunnel 13/42

14 LHC K Helium Refrigerator Compressor stations 14/42

15 Compressor station of LHC K Bldg: 15 x 45 X 9 Pinput : 4.5 MW Cool: 500 m3/h Noise: 105 dba 15/42

16 LHC K Refrigerator Process cycle for Air Liquide LN2 Expansion Turbines Heat Exchangers 16/42

17 Cold Boxes of LHC K Key components: Expansion turbines on gas bearings, plate fin heat exchangers, cryogenic valves, vacuum shell Bldg: 15 x 10 X 10 Pinput : 40 kw Cool: 20 m3/h Noise: 85 dba 17/42

18 K Refrigerators performance K to 75 K K to 20 K - 41 g/s liquefaction 400 COP 250W/W TORE SUPRA Carnot Carnot Limit RHIC TRISTAN CEBAF HERA LEP LHC 18/42

19 300 First cool-down of LHC sectors First beams around LHC Temperature [K] Christmas and water maintenance shut-down Cool-down 0 time: t cold mass Nov- Dec- Jan from 10 wks to below 5 wks now Short in connection cryostats and repairs 04- Feb Mar Open Days 31- Mar Apr May Jun Simultaneous Cryo start/maintain All sectors at nominal temperature UX85 Ph1 works 21-Jul Aug ARC56_MAGS_TTAVG.POSST ARC78_MAGS_TTAVG.POSST ARC81_MAGS_TTAVG.POSST ARC23_MAGS_TTAVG.POSST ARC67_MAGS_TTAVG.POSST ARC34_MAGS_TTAVG.POSST ARC12_MAGS_TTAVG.POSST ARC45_MAGS_TTAVG.POSST If 100 kg/m, 45km equals a LHC sector, with cool-down time in weeks! 15- Sep /42

Pre-cooling to 80K with LN2 Cooldown to 80 K: 600 kw per sector with up to ~5 tons/h liquid nitrogen 200 P18 10000 180 P2 9000 P4 LN2 deliveries per site 160 140 120 100 80 60 40 P6 P8 Total per day

20 Pre-cooling to 80K with LN2 Cooldown to 80 K: 600 kw per sector with up to ~5 tons/h liquid nitrogen 200 P P P4 LN2 deliveries per site P6 P8 Total per day Cumulated LN2 deliveries for LHC [tons] Jan Jan Feb Mar Apr May Jun Heavy logistics and manpower: (so far from 6h to 22h, 6 days/week) : 500 trucks (20 tons) for 7 sectors in 5 months : 400 trucks (20 tons) for 5 sectors in 3 months 20/42

Interconnections in LHC tunnel 65 000 electrical joints Induction-heated soldering Ultrasonic

Assurance!!! Design issue, to be cured in 2013 0.

21 Interconnections in LHC tunnel electrical joints Induction-heated soldering Ultrasonic welding Very low residual resistance HV electrical insulation Compulsory high level Quality Assurance!!! Design issue, to be cured in % to 1% in-situ leaks 19 left as acceptable 6 appeared (4 cured) cryogenic junctions Orbital TIG welding Weld quality Helium leaktightness 21/42

22 Present LHC baseline (1/3) LHC ARC: CRYOGENIC AND INSULATION VACUUM BASELINE DESIGN Insulation Vacuum sectorization: Magnet vacuum barriers Jumper vacuum barriers Cryogenic line vacuum barriers QRL vacuum jacket Magnet vacuum vessel Cold-mass sectorization: Spacing of vacuum barriers compatible with pressure protection of helium pipes in case of degradation of the insulation vacuum, and additional pumping ports available to mitigate leaks if necessary! Q7R Q9R Q11R Q13R Q15R Q17R Q19R Q21R Q23R Q25R Q27R Q29R Q31R Q33R Q33L Q31L Q29L Q27L Q25L Q23L Q21L Q19L Q17L Q15L Q13L Q11L Q9L Bus-bar plugs Safety relief valves Cooldown and fill valves A B A B A B A B A B A C D A B A B A B A B A B A B A Q7R Q9R Q11R Q13R Q15R Q17R Q19R Q21R Q23R Q25R Q27R Q29R Q31R Q33R Q33L Q31L Q29L Q27L Q25L Q23L Q21L Q19L Q17L Q15L Q13L Q11L Q9L Q7L 22/42

23 Main cryogenic line performance Heat inleaks E+F B+C+D [W] (50-75 K) (4-20 K) Calculated Measured /- 400 (~ 2.8 W/m) 634 +/- 50 (~0.2 W/m) Best: 0.05 W/m inner pipe 23/42

24 Control logic must handle long time delays D C E B Density [g/l] Mass [kg] Time flight C [3B, 5K] h D [1.3, 8K] h B [0.015, 4K] ' F along 3.3 km sector hours 5.5 Slow propagation of «warm bump» along the sector Temperature R2_TT961 07R2_TT961 13R2_TT961 21R2_TT961 29R2_TT961 33L3_TT961 25L3_TT961 17L3_TT961 09L3_TT Apr :00 22-Apr :00 22-Apr :00 23-Apr :00 24/42

Electrical Feed Boxes Shuffling module Connection to magnets Vacuum equipment VAA Current lead chimneys x 16 2 per LHC Point 6kA leads 13kA leads High current module 13kA & 6kA leads SHM/HCM

25 Electrical Feed Boxes Shuffling module Connection to magnets Vacuum equipment VAA Current lead chimneys x 16 2 per LHC Point 6kA leads 13kA leads High current module 13kA & 6kA leads SHM/HCM interconnect Jumper cryo connection to QRL Supporting beam 6kA leads Removable door 600A leads HCM/LCM interconnect Low current module 6kA & 600A leads LHC: 3.4 MAmp 1.9K 4.5K Global electrical protection system (quench detection) mandatory 25/42

26 Electrical feedbox with current leads LSSL2 of the LHC 26/42

27 Superconducting Links A kind of power line built in low-load rigid cryogenic transfer line 76 m with 3 branches, 11 x 6 ka + 12 x 600 A Temperature of the 3 branches 0.15 K 10 hours 517 m, 44 x 600A Hot spot 27/42

Controls for LHC cryogenics 21300 AI, 7000 AO, 18400 DI, 4200 DO, 4000 analog control loops Central Control Room OWS [1.

28 Controls for LHC cryogenics AI, 7000 AO, DI, 4200 DO, 4000 analog control loops Central Control Room OWS [1..x] PVSS DS Sector Cryo instrumentation expert tool PVSS DS Local Cryogenic control room! OWS [1..x] Return Module! FECs (FESA) RM sector 81 RM sector 78 RM sector 78 UNICOS WFIP Networks (7) PROFIBUS DP networks TT, PT, LT, DI, EH CV 28/42 PROFIBUS PA networks More than 120 PLC for the cryoplants and the 8 sectors

29 Outline Introduction to CERN and LHC Cryogenics Relevant hardware and key performance Operation, maintenance organisation and results so far Perspectives for superconducting power lines Summary 29/42

30 Affectations LHC Cryo CRG-OA LHC Cryo OP Structured alarms elogbook Procedures Documentation Ing. OP référents academic experts Ing. production Site management Opérateurs Sites + Shifts Cern Control Center: Monitoring on shift 24/7 Site control rooms: periodic checks, 1st line intervention + Industrial partner teams in local control rooms (! 15 personnes Serco) High level recruitment, training (academic - on the job - shadowing), certification for operation (10months), join & leave about to work 30/42

Maintenance principles A Simple adjustments foreseen by the component, equipment or installation supplier by the means of components that are accessible without disassembly and opening of the

31 Maintenance principles A Simple adjustments foreseen by the component, equipment or installation supplier by the means of components that are accessible without disassembly and opening of the component. and/or The replacement of consumables that can be accessed safely as bulbs, filters, oils, etc. Operators Preventive Corrective B The repair or maintenance by standard exchange of elements foreseen for this type of repair and/or Minor operations of preventive maintenance. Contractor Predictive Time dependent If failure C The identification and diagnostics of the failure which may be followed by the replacement of components. and/or The global adjustment and calibration of the equipment/ component. Contractor D Complex tasks of corrective and preventive maintenance, in particular the disassembly of a system, exchange and/or repair of components, reassembly and adjustment of the system, but it is excluding the rebuilding of components. and/or The replacement of an assembly of electrical components. Contractor or CERN Simply applying standardised methods! E Extensive repair, renovation and rebuilding tasks. Rebuilding means in this context the manufacturing of components on the basis of a manufacturing drawing (examples are the manufacturing of a rotor screw, the rewinding of a large motor winding and the manufacturing of a cooler). CERN 31/42

Software tools Spares: 6 000 - Number of

5k<<50k: 2+ <5kCHF: 2 to n CAMMS Infor EAM

de maintenance Arbeitsaufträge Gestion du

32 Software tools Spares: Number of assets: >1MCHF: 0 50k<<1M: 1 5k<<50k: 2+ <5kCHF: 2 to n CAMMS Infor EAM Gestion des biens Asset-Management Ordres de maintenance Arbeitsaufträge Gestion du magasin de pièces de rechange Ersatzteillagerverwaltung!"#"$%"&'$ ()*"+,'-! Reporting Business Objects Affichage/impression simplifiés einfache Anzeige-/ Druckfunktionen Analyse de données Datenanalyse KPIs Documents EDMS (based on Agile PLM) Documentation Dokumentation Dessins Zeichnungen Rapports Berichte 32/42

33 LHCCryo Availability 2010 Based on LHC_Global_CryoMaintain signal per unit of time For Beams All included 70 Availability Powering tests Easyer for us with LHC being presently commissioned with beams not yet nominal and periodic scheduled technical stops - LHC Operation: 6 periods of 6.5 weeks - Technical stops: 6 x 0.5 wks (small corrections) - Xmas break: 8-10 weeks (medium works) 25-Jan 22-Feb 22-Mar 19-Apr 17-May 14-Jun 12-Jul 9-Aug 6-Sep 4-Oct 1-Nov 29-Nov Daily "Global LHC Cryo" weekly AVG Monthly AVG Scheduled Stops 33/42

34 100 LHCCryo Availability 2011 Based on LHC_Global_CryoMaintain signal per unit of time Availability Rather a very nice start for 2011 With availability not yet reliability! 0 24-Jan 21-Feb 21-Mar 18-Apr 16-May 13-Jun 11-Jul 8-Aug 5-Sep 3-Oct 31-Oct 28-Nov Weekly 2010 Monthly 2010 Scheduled Stops Daily 2011 Weekly 2011 Monthly /42

35 Availability, key performance 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 100% 95% 90% 85% 80% 97% 98% 99% 100% Target for HWC (2008) Target for LHC operation (2009) % 50% 60% 70% 80% 90% 100% Individual State of the art availability for a single cryoplant: 99.5% with 12 weeks maintenance / 4 years ( ) 35/42

36 Outline Introduction to CERN and LHC Cryogenics Relevant hardware and key performance Operation, maintenance organisation and results so far Perspectives for superconducting power lines Summary 36/42

37 Context 50 km 50 km 50 km Thermal screen (return) Cryoplant SC cable duct (supply) Hydraulic plug Cryoplant 1000 km: 10 plants every 100 km Configuration of a long sc power line system is a tradeoff between: Minimised number of cryoplants to reduce capital costs, complexity and increased operational efficiency. Large flow rate to be circulated would require large diameter to match acceptable pressure drops, therefore larger helium inventory Minimised dimensions of the cryogenic piping to ease installation and limit the quantity of cryogenic fluids Distribution over unprecedented distances (50km) to be engineered! 37/42

38 Very low heat loads long lines 50 km 50 km 50 km Thermal screen (return) Cryoplant SC line Cryoplant Vac tank shield SC line Vac tank supply return SC cable duct (supply) Hydraulic plug Approx. 400 mm Approx. 400 mm Heat loads distribution: Dominated so far by static heat ( x5 w.r.t dynamic loads from cable) 0.05 W/m considered as static heat on inner pipe, which is ultimate achievement with rigid pipes welded every 12-18m Obvious need to get hundreds meters prefabricated elements (flexible or semi-rigid) to ease installation and Quality Assurance So far, these lines have a heat load x5 larger than considered Significant progress required in this field! 38/42

39 Sectorisation and altitudes Effects linked with change of altitude: Pressure difference (Ro.g.z) due to gravity (1.2 bar for 100m for LHe) Temperature difference (g.z) due to increased enthalpy (10% for 100m) => Usual turnaround implies re-coolers with valves, instrumentation sc line Re-cooler Re-cooler Re-cooler Pro/Cons associated with sectorisation: Increased complexity + Pressure protection: Safety valves (helium pipes and insulation vacuum) + Re-cooling time: Significant gain as each loop will be treated in parrallel Dedicated engineering required to address these serious physical and technical issues! 39/42

40 Cryoplant efficiency & availability Efficiency Availability Product Conventional Superconducting sc dreams Obvious efforts to be made on global availability: Not realistic to consider 15 days of downtime + maintenance per year! Obvious need of redundancy for cooling capacity, implying an interconnection box between cryoplants and power lines, and potentially a loss of efficiency (hot running spare for automatic switch!) Direct impact on investment costs! Dedicated engineering required to address these serious global issues! 40/42

41 Summary LHC cryogenics is the largest, the longest and the most complex cryogenic system worldwide. We could achieve a reasonable availability (around 95%) so far with beams. This demonstrates that there are no big issues in concept, technology or global approach for operation, within LHC environment, schedule and boundary conditions. If one could think of applying such technology to GW power lines of 1 000km long, some efforts should be invested in: Very-low heat leaks cable in flexible line design of several 100m modules Sectorisation over long distance and acceptance of moderate altitude variations Assembly and safety valve concept for reliability in outdoor environment Cryoplant reliability (and efficiency) For the time being, we have difficulties to apply this concept with significant altitude changes (1000m) and in no-man s land areas 41/42

42 Summary Yes at CERN with specific efforts (at least our experience) Why not, at least for crowded areas, but availability and practical application to be checked A real challenge with physical and practical constraints! 42/42

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EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH CERN LIBRARIES, GENEVA llilliiiillllllllilllllllllllllllllllllllil CERN AT, (CR, 94'36 QERN-AT-94-36 ;.t W4?. Four 12 kw/4.5 K Cryoplants at CERN S. Claudet,