LHC availability model for FCC study Arto Niemi

LHC availability model for FCC study Arto Niemi Acknowledgement: A. Apollonio FCC 3 D Schematic J. Osborne, C. Cook, A. Navascues 2

Contents • • Scope & Motivation LHC operations Operations Model validation Plans to improve the model FCC Study Aspects Conclusion

Scope of the Study q Evaluate the suitability of industrial reliability methods for the domain of particle accelerators… q …taking the LHC as a case study q Identify and analyse possible design and operational scenarios for a h-h Future Circular Collider q Identify key impact factors on availability and luminosity production q This reliability & availability study DOES NOT intend to give specific guidelines for individual system design and optimization 4

FCC-hh operation & luminosity 5 year long operation periods • 3. 5 years operation periods with • • radiation damping: t~1 h 1 year HW comm. , MDs, short stops 2. 5 years lumi. run with 70% availability • 1. 5 year shutdown 2 periods at baseline parameters (10 yrs) • Peak luminosity 5 x 1034 cm-2 s-1 • Total of 2. 5 ab-1 (per detector) phase 1: b*=1. 1 m, DQtot=0. 01, tta=5 h, 250 fb-1 / year phase 2: b*=0. 3 m, DQtot=0. 03, tta=4 h, 1 ab-1 / year 3 periods at ultimate parameters (15 yrs) • Peak luminosity <=30 x 1034 cm-2 s-1 • 5 ab-1 period total of 15 ab-1 O(20) ab-1 integrated luminosity/experiment consistent with physics goal: 20 ab-1 in total Detectors must sustain a total of >20 ab-1 and >5 ab-1 between maintenance stops Machine design to support 3. 5 year operation periods w/o warm up or long stops Future Circular Collider Study Michael Benedikt 2 nd FCC Week, Rome, April 2016 5

Accelerator Schedule Shutdown Operation Years HW Commissioning Beam Commissioning Luminosity Production Technical Stop Machine Studies Weeks Machine Cycle Stable Beams Failure Precycle Hours 6

Turn-around time Beam dump Stable Beams Adjust Ramp-Squeeze Prepare Ramp Injection Probe Injection Physics Setup Ramp down Beam dump Energy FCC-hh operational cycle (= LHC) t Reyes Alemany et. Al FCC week 2016 7

LHC – Our Reference q What do we know from the LHC? (25 ns Run in 2015) 8

ELMAS Software • Model build in collaboration with Ramentor Oy • • Probabilistic model • • • TUT spin-off company Combines semi Markov-chains with dynamic fault tree Calculation is based on Monte-Carlo simulation www. ramentor. com Software allows using custom java libraries and code in models 9

Model Implementation Machine Cycle Stable Beams Failure Precycle Hours Probabilistic phase transitions (Markov chain) Randomly generated failures (base on calculated probability distributions) q Example: Failures in Injectors only relevant at Injection from the LHC perspective 10

High level models 11

Data for the model Failure rates • Repair times • Accelerator Fault Tracker • (aft. cern. ch) 12

2012 Data Phase Length Idle 3 h Injection 52 min Ramp and Adjust 49 min Ramp down 35 min Beam Peak Lumi. [cm-2 s-1] Luminosity Lifetime [h] Average SB length [h] Low Int. 2. 5*1033 10. 52 9. 6 High Int. 6. 28*1033 10. 05 9. 6 Parameters for Simple Models for Luminosity Production by J. Wenninger Node SIS BIS Controls LBDS Access Collimator Experiments BI Vacuum Injection Misc. PC QPS RF TI Cryogenics MTBF [d] 207 9. 9 7. 4 6. 9 4. 9 10. 9 5. 3 5. 2 3. 9 3. 8 3. 1 6. 5 6. 7 MTTR [h] 0 1. 3 1. 2 1. 8 1. 5 1. 4 1 3. 8 2. 3 2. 5 1. 9 1. 7 3. 8 8. 7 + Injector availability and beam instabilities 13

Model Validation: 2012 Luminosity Production q Developed model allows predicting 2012 LHC luminosity production (23. 27 fb-1) q Results from 1000 model iterations sufficient for re-production of actual operation (~10 min) 14

Simulation Results One year Ten years 15

Planned improvements to the Model 16

Example: Cryogenics Fault Tree q Model complexity – impractical to model the entire accelerator to a sufficient level of detail within the FCC study q Start from top contributors to downtime q Collaboration with TU Delft for cryogenic system modelling and prognostic methods LHC Cryogenics fault tree BONUS: the developed cryogenic fault tree will be used in 2016 for fault data capture by the cryo-operations team 17

Cryogenics Fault Tree Principle System Boundary Primary Failures Utilities (e. g. electricity) Sub-Systems Users (e. g. magnets, magnet quenches) System location: • 4. 5 K Refrigerator (Surface) • 1. 8 K Refrigerator (Underground) • Sectors / Distribution (Underground) Secondary Failures 18

Injector Chain Model • • • Injection to FCC done with different machines Need to understand their availability Injection caused delays 2015 (Delfine Evian 2015) • Phase twice as long than ideal • Electron cloud sub-optimal filling scheme • IQC rejected about 20 % of the injections • Failures in Injectors Planned improvements in model • Length of the injection phase process model • Fault trees for injectors 19

FCC Reliability Requirements • Combine operational parameters • • • Cycle (R. Alemany) Luminosity production (X Buffat) Injection (L. Stoel) Identify the key impact factors for availability • Derive failure rates, repair times that can be tolerated (unavailability budget) • (FCC week presentations) 20

FCC-hh – A Complex Machine q 4 times bigger machine = 4 times less availability? q Improved reliability for high-impact systems (redundancy) q Reduce corrective maintenance in favour of condition-based maintenance q High availability of the injector chain q Extremely efficient cycling q Optimization of machine protection settings q Beam stability Sensitivity analyses to key contributors for luminosity production should be performed 21

Conclusion • LHC Operations model • • Ready and validated Extensions planned • Injector chain • System fault trees • FCC CDR • • • Identify key impact factors for availability FCC availability requirements How to improve availability / what is the potential?