wir schaffen wissen – heute für morgen do you believe in operation statistics? presented at the...
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Wir schaffen Wissen – heute für morgen
Do you believe in Operation Statistics?Presented at the Accelerator Reliability Workshop 2011
Andreas LüdekePaul Scherrer Institut
Paul Scherrer Institute (PSI), Switzerland
PSI: Swiss national research center1300 employees
Proton facility: 1 MW cw beam– Spallation neutron source
PSI West: Large Research Facilities
Proscan SC cyclotron– Cancer therapy Swiss Light Source (SLS)
– e- storage ring– 400mA, 2.4 GeV
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 2
Swiss Light Source Operation
• Swiss Light Source is• In operation since 2001• A user facility with 19 beam-lines in operation• Providing ~ 5000 hours beam to users per year
• Users need to apply for beam time• Just 30% of the proposals are accepted• Accepted users need to wait about 6 month for beam time
• One important metric to judge machine quality
€
Availability =Delivered _Beam _Time
Scheduled _User _Time
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 3
3rd Generation Synchrotron Light Sources: AvailabilityAv
aila
bility
[%]
YearAndreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 4
Availability: "Concours des Alpes"Av
aila
bility
[%]
YearAndreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 5
Availability: "Concours des Alpes"Av
aila
bility
[%]
YearAndreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 6
Metrics of the Swiss Light Source (SLS)
• Availability definition:
• “Delivered_Beam_Time” = “Beam_for_Users” during “User_Time”• “User_Time" = “Scheduled_User_Time" + "User_Reserve_Time”
• Example for 2005:€
Availability =Delivered _Beam _Time
Scheduled _User _Time
€
Availability =4777h +175h (reserve )−82h (outages)
4777h=101.6%
€
Availability uncompensated =4777h +175h(reserve ) −82h(outages)
4777h +175h(reserve )= 98.4%
• Uncompensated Availability
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 7
Elettra Metrics for Availability
• Thunderstorms are excluded from failure statistics at Elettra
• Example from 2005:
€
Availability =User _Time −Outages+Outages(Thunderstorms)
User _Time= 93.2%
€
Availability (Storms) =User _Time −Outages
User _Time= 92.3%
• Availability including outages from thunderstorms:
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 8
Availability: "Concours des Alpes” correctedBa
re A
vaila
bility
[%]
YearAndreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 9
Special Events: ESRF 2005 and the Crotch Absorber
● In March 2005―A water-to-vacuum leak―Five days of user operation lost 120 hours downtime
● ESRF statistics 2005―Availability 97.6%, ―Total User Operation 5496 hours 131 hours downtime
• How can that be? ―All users of 5 days re-scheduled―Not counted as downtime
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 10
What can we learn from this?
● Availability statistics not proportional to system reliability
● But large effort spend to compile downtime statistics
● Accurate failure data exists, but kept internal. Why?
● If that would be public, what could it be used for?
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 11
RF arcing at the Swiss Light Source
• Background• SLS has 60 to 100 beam outages per year• About 20 outages were caused by RF arcs
• Inquiry• Asking around at the EPAC’08: “What is your experience with arc detectors?”• Answer: arc detectors are often unreliable!
• Action• We are replacing detectors with arc-coincidence detectors
• Result• No arc interlock from any upgraded detector!• Single diodes still show arcs, but do not cause interlocks
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 12
• Conclusion• We had in 10 years 200 unnecessary beam losses!
What can we do?
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 13
• What we do now– We do your own mistakes– Sometimes we share selected insights during workshops
• What we should do– Learn from the failures of others– Create a database of all outages of many facilities!
• How to do that?– Define a simple document format– Provide a web-platform to publish downtime event data
• I’ll start, will you join?
• Participate in the Friday morning discussion!
• .
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