Jan Uythoven for the Reliability Sub Working Group (March 2004 – June 2005) & ….

1. Availability Workshop CERN28 November 2013Dependability calculations prior to 2008 and operational experience during the first LHC run Jan Uythovenfor the Reliability Sub Working Group (March 2004 – June 2005) & ….

2. Reliability Sub Working Group 13th and last meeting on 17th June 2005 Many of the players are still around and here today Jan Uythoven, Prior 2008 and experience run I

3. The model used – LHC Project Report 812 60 % P=0 15 % 15 % 10 % Simplified model of the LHC machine protection system Main players: PIC, QPS, BLM, BIS, LBDS Fast losses and slow losses, redundancy between systems Jan Uythoven, Prior 2008 and experience run I

4. Redundancy between systems 15 % P=0 15 % C=1 Presentation R.Filippini, 18/3/2005 Jan Uythoven, Prior 2008 and experience run I

5. Resulting numbers from the study MP unsafety is 2.310-4 /year = 5.8 10-7 /hour = SIL3 42 false dumps is about 10 % of all dumps in the model200 days of 2 fills per day, 2 h between fills Contributions from the different “PhD students” Result depends on operational scenario Jan Uythoven, Prior 2008 and experience run I

6. 7 years later: Compare with Run I results 2010 Estimated 10.5 % Jan Uythoven, Prior 2008 and experience run I

7. More from Ben @ Evian December 2012 Very good – global – agreement between prediction and what was measured The QPS is the only system which systematically seems to behave worse than expected: major changes LS1 Availability ok  model ok  safety ok What is this trend on the BLM system ???? Jan Uythoven, Prior 2008 and experience run I

8. Reaction from Christos Statistics Identify Act • How is the statistics done ? • Only above 450.1 GeV: 2012 give 15 BLM faults • If all interlocks: 31 BLM faults in 2012 • If all faults: 70 BLM faults in 2012 • But in all statistics the trend was spottedand the problem identified • Conclusions made on the equipment side • The trend over the years was spotted • The failure mode identified: optical link • Action LS1: replace / clean optical fiber connections Jan Uythoven, Prior 2008 and experience run I

9. Christos @ Annecy 2013 Jan Uythoven, Prior 2008 and experience run I

10. Machine Protection  Machine Availability 2010 Estimated 10.5 % Not addressed at the time Jan Uythoven, Prior 2008 and experience run I

11. Assumptions used by the model of RSWG • The predicted number of dumps due to the MPS fit the model as statistics only took into account all fills above 450.1 GeV • The model assumed 2 fills per day of 10 h • Only dumps in physics • We did have about the 2 fills per day,but they were not 10 h long … • However, down time at injection or without beam can be as important as downtime during physics • The model should be extended to consider luminosity production and not only the number of beam dumps • The model should also be extended to all equipment and not only machine protection elements • MPS is only in a limited number of cases the cause of the down time • The model was really good for machine safety but not that useful for estimating machine availability Jan Uythoven, Prior 2008 and experience run I

12. Where did we go after 2005? Predictions of the Sub-Working group For a Sub-System of the LHC Machine is safewithout too much impact on availability We need to have common metrics of faults LHC Run I StatisticsAgree with the predictions ! For availability it needs to be extended to all equipment LHC Availability Working Group To be applied to luminosity and not # faults Jan Uythoven, Prior 2008 and experience run I

13. LHC Availability Working Group À la Ben: The Availability Working Group (AWG) has been created on 20/06/2012 after the endorsement of the LMC committee, with the purpose of creating common definitions and metrics for LHC dependability, modelling LHC availability using data from system experts and operations, identifying strengths and weaknesses for LHC machine availability and developing strategies for improving availability of LHC, LHC upgrades and future machines Jan Uythoven, Prior 2008 and experience run I

14. LHC Availability Working Group 8 meetings so far Synergy between equipment groups to measure and improve availability of their systems Collaboration with the Maintenance Management Project which also aims at measuring the same faults Workshop on Machine availability and dependability for post LS1 LHC TODAY Jan Uythoven, Prior 2008 and experience run I

15. Conclusions • The simplified model of the machine protection system (2005 !) has proven to be amazingly accurate • Although the top model is very simple, it is based on very detailed and complex models of the individual systems: a lot of work! • One PhD per subsystem • Comparison with machine run I data gives us • Confidence in the machine safety • Handle on machine availability of some subsystems • Improve weak points, equipment which is underperforming • Find trends and act • Fault statistics can be analysed at system level down to component level • Compare with dependability models of the operational equipment • Not all equipment has a dependability model • Extension of 2005 model – AWG • Need to be able to measure properly, operational statistics • Extend to outside the Machine Protection System • Quantify the effect on luminosity Jan Uythoven, Prior 2008 and experience run I