Operation of the LHC Cryogenics system and interface

Operation of the LHC Cryogenics system and interface with beam & machine operation S. Claudet (CERN, Geneva) on behalf of the “Cryogenics Group” Technology Department Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation

Outline • Introduction to LHC Cryogenics • Operation, organisation and results • Availability and interaction with beam operations • Summary Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 2

LHC accelerator p-p collision 1034 cm-2. s-1, 14 Te. V, 0. 5 GJ stored energy Machine operation Technology 24 km of superconducting magnets @1. 8 K, 8. 33 T Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 3

Layout of LHC cryogenics 8 x 18 k. W @ 4. 5 K 1’ 800 sc magnets 24 km & 20 k. W @ 1. 8 K 36’ 000 t @ 1. 9 K 130 t He inventory Magnets LHC cryogenics is the largest, the longest and the most complex cryogenic system worldwide Workshop Accelerator Operation 2012, SLAC Distribution LHC Cryogenics, interface with beam operation 4

How does it compare ? Before LHC: existing experience for design, safety, controls, operation, availability, … ITER Tevatron, RHIC, Jlab, SNS, HERA, Tristan, … Workshop Accelerator Operation 2012, SLAC We did not start from scratch! LHC Cryogenics, interface with beam operation 5

LHC compressor station (x 8) 4. 2 MW input power Bldg: 15 m x 25 m Oil/Helium Coolers Workshop Accelerator Operation 2012, SLAC Compressors Motors LHC Cryogenics, interface with beam operation 6

18 k. W @ 4. 5 K Refrigerators (x 8) 33 k. W @ 50 K to 75 K - 23 k. W @ 4. 6 K to 20 K - 41 g/s liquefaction LHe: 3’ 600 l/h 4 m diam, 20 m long, 100 tons Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 7

Cold under vacuum 300 K under atmosphere 1. 8 K Units with cold compressors (x 8) Cold Compressor Active magnetic bearings 3 -phase induction Electrical motor (rotational speed: 200 to 800 700 Hz) 200 to 125 g/s GHe from 15 mbar to P atm with 3 or 4 stages Fixed-vane diffuser Outlet Spiral volute Pressure ratio 2 to 4 Axial-centrifugal Impeller (3 D) Inlet Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 8

Electrical feed boxes for current leads 48 Boxes, 1200 leads LSSL 2 of the LHC Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 9

One LHC sector: production-distributionmagnets Total for 8 sectors: • Extremely large installed cooling capacity Compressors: • Complexity associated with 1. 8 K units 64 Turbines: • Extremely large distribution system 74 Cold Comp. : => Recovery from failures can last 28 from few minutes to 20 hrs, exceptionally 2 -3 days Leads: x 13. 5 1’ 200 I/O signals: From LHC Magnet String 60’ 000 test PID loops: 4’ 000 3. 3 km Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 10

Interfaces: follow-up electrical perturbations EL perturbations and their impact on our LHC Cryo system Electrical systems recover in ms Voltage change [%] Cooling systems recover in min Cryo systems recover in hrs => A big incentive to be as tolerante to glitches as possible Duratio n [ms] Typical tolerance envelope Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 11

Main reasons to superconducting For accelerators in high energy physics • Compactness through higher fields st o C l a t i p a C Ebeam ≈ 0. 3. B. r Ebeam ≈ E . L [Gev] [T] [m] [Gev] [MV/m] [m] Be sure that at design stage, working at higher temperature was considered, but not selected to maximise LHC beam energy => Cryogenic systems takes longer to recover from failures than conventional ones (but we work on it!) Cost g n i t a r • Saving operating energy Ope Electromagnets: Acceleration cavities Resistive: Pinput ≈ Ebeam Pinput ≈ Rs. L. E 2/w Superconducting: Pinput ≈ Pref Rs ≈ RBCS + Ro RBCS ≈ (1/T) exp(-BTc/T) Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 12

Interactions between LHC systems Powering OK or interlock Static and Dynamic heat loads Workshop Accelerator Operation 2012, SLAC Beam related Dynamic heat loads LHC Cryogenics, interface with beam operation 13

Outline • Introduction to LHC Cryogenics • Operation, organisation and results • Availability and interaction with beam operations • Summary Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 14

Key factors for operation • Equipment architecture: – Central liquefier to intermediate buffer, distribution decoupled On-call adapted – Cooling capacity production in line with demands • Type of operation – Transients (cool-down / warm-up) or various recovery – Alarm monitoring, simple reset actions, calling for experts LHC: A huge and complex – Detection of process degradation and curing action system without significant – HW checks and preventive treatment of slow buffer and frequent operator actions required evolving problems Dedicated 24/7 required so • Frequency of required actions: LHC Cryogenics, interface with beam operation 15 Workshop Accelerator Operation 2012, SLAC

Structure - Coordination - Outils Instrum-Cryolab Methods - Logistics Management Operation Accel. Operation Detect. Electricity. Controls Mechanics Coordinations: • Team Leaders + Management (1/wk) • Performance panel (1/2 wks) • Operation / Maintenance panel Tools (web interface DB oracle): • Methods & Tools panel • e-logboog operation for any change of configuration (wanted or not) or observation and diagnostic request • Diagnostic tables, work-orders, intervention reports • Asset & spares management, intervention procedures • Maintenance plan • Scheduling Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 16

Staff & team evolution People should be able to quit, newcomers should be integrated • High level requirements for recruitment (Bachelor & Masters) • Formalised induction process: Academic training - On the job training - Shadow shifts => Certification after ≈ 10 months as shift operator (alone!) • Senior operator (>3 yrs): Able with all sub-systems, ability to optimise production-needstime • Certification diploma: Written - Site - Simulator - Improvement study (report + presentation) • If selected for indefinite contract: – Operation for 5 to 10 years – Ability to become “production Eng. ” as site responsible Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 17

Cryo operator in Cern Central Control room Shift 24/7 Fixed displays Tendancy curves (summary) Process synoptics and orders Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 18

Operation, indicators Efficienc y Alarms Poweri ng Global availability Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 19

Outline • Introduction to LHC Cryogenics • Operation, organisation and results • Availability and interaction with beam operations • Summary Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 20

Availability: a signal Yes/No is required T 2 = Achieved up time during required time / Required time x 100 (operational availability) Cryo Maintain: Few important conditions checking integrity CM of HW, with slow power abort in case this signal is lost CS (leading to beam dump!) SP set. CS point CM Cryo Start: set of conditions to allow powering of concerned T 2 indicator w. r. t EN 15341 C M sub-sector, with no action if powering started (illustrates good stability of process) CS CM Sum CM 8 sectors: Global availability Possibility to treat thousands of channels in a structured way to match at best the LHC powering sub-sectorisation and the cryo sub-sectorisation Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 21

LHCCryo global availability 2012 Target 2012 95% 201 1 201 0 200 9 L 7 TT 891 2 x. P 8 CCs SEU? P 8+R 5 Workshop Accelerator Operation 2012, SLAC - Excellent 1 st part to Tech. STop P 4 P 18 CCs P 4 oil ice - Heavy works done during Technical Stop #1, and cabling weakness caused difficult recovery - Very moderate impact from High Luminosity operation in 2012 LHC Cryogenics, interface with beam operation 22

Performance and origin of downtine Global availability as seen by LHC during beam operation periods Others according to relative ratio of their average for the 8 sectors Evolution: - 2010: Correcting early Cryo bugs (260 days) (271 days) (137/290) (Full days, Mondays & Fridays of Technical Stops not counted here) Workshop Accelerator Operation 2012, SLAC - 2011: Adapting to SEU (corrected @Xmas) - 2012: So far rewarding !!! LHC Cryogenics, interface with beam operation 23

Availability: from global to single plant Considering 8 independent sectors 20102011 Single sector and cryoplant Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 24

Indicators: recovery categories & tendency + Better global Nb control/tuning (operation, stops instrumentation) - ! SEU ! • Less Cryo induced failures, . (but 3 VERY LONG ones!) - More Supply (EL) failures + No longer recurrent - ! SEU ! Cold Compressors particular issues (Leaks, electronics) From the books: Annoying if frequent, to be kept low with moderate efforts Immediate effect of (good!) practice Workshop Accelerator Operation 2012, SLAC Nice tendency, promising for Serious cases requiring specific monitoring and 2012 or new surprises to significant efforts come up? LHC Cryogenics, interface with beam operation 25

Operation structure & approach. Control rooms: site - CCC- • 2007/2008 cool-down & HWC: office Per site, one experienced engineer with agreed minimum protocol to guide a local team of operators, with help of support teams (instrumentation, experts, controls) • Since 2009 and operation with beam: One operator in shift 24 h/7 d, more transverse structure site/Cern. Control. Center, procedures & operation tools • For machine controls (temperature, level, pressure): Basic interlocks and simple PID loops with generic tools for fast orders, now completed with automated sequences & procedures Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 26

Power Consumption for LHC Cryogenics Stop Cryoplan t Operation with 8 plants Tests Installed power (3 MCHF / year !!!) Gain ≈ 8 MW (20% of installe Cryo optimized power) Cool dow n HW C 700 h Power [MW] Net gain ≈ 50 GW. h per year LHC physics 6200 h 6500 h 2009 Cryo unavailability breakdown 91% Cryo Availability 2010 1 3 Workshop Accelerator Operation 2012, SLAC 90% Cryo Availability 2011 3 5 4 3 LHC Cryogenics, interface with beam operation 27

Helium invenrory [tons] Helium inventory follow-up Workshop Accelerator Operation 2012, SLAC • Now < 30 kg/day • With 50 kg/day in 2011 and better control @Xmas, tendency to be confirmed • @50 CHF/kg - 50 kg/day # 2’ 500 CHF/day - 150 t # 7. 5 MCHF LHC Cryogenics, interface with beam operation 28

Interfaces with Beam-OP • HW signals: – Cryo Start and Cryo Maintain towards Powering Interlock module • SW panels: – Cryo web page • People in Control Room (LHC): – 1 Eng in charge + 1 operator Text zone – 1 Cryo operator – 1 operator for technical infrastructure • Possible evolutions ? – Closer discussions with Eng. In charge in case of cryo problem – Other operators involved to help diagnostics/recovery – No longer cryo operators at night (on call only) Workshop Accelerator Operation 2012, SLAC LHC Cryogenics, interface with beam operation 29

Summary • LHC cryogenics is the largest, the longest and the most complex cryogenic system worldwide. We could achieve a reasonable availablity (> 90 %) so far with beams. This demonstrates that there are no big issues in concept, technology or global approach for operation. • Despite all our efforts, we had very hard time and lengthy commissioning to learn how to tune all these sub-systems together while permanently consolidating what was not conform. Experience has been converted into automatism, procedures, tools, training • Cryogenics operation is well integrated in central control room with LHC main systems, but operated/supported independently (about 50 people) • Maintenance is as well reaching an efficient LHC Cryogenics, interface with beam operation 30 Workshop Accelerator Operation 2012, SLAC