A. Denker

Reliability gemäß LEO: AusfallsicherheitBetriebssicherheitFunktionsfähigkeitVerlässlichkeit Zuverlässigkeit

Bericht vomAccelerator Reliability WorkshopARW 2011

Statistik: Übersicht

1. 2002 ESRF2. 2009 Triumf3. 2011 Kapstadt

41 Beiträge von Beschleunigern– 78 Teilnehmer, ohne “Locals”: 1/3 Amerika, 1/5 Asien, knapp ½ Europa

3 Beiträge aus anderen Einrichtungen– Kernkraftwerk Koeberg, – SALT (South African Large Telescope): jwd, Temp.gradienten– South African Square Kilometer Array Project:

jwd, möglichst ferngesteuert, da bereits ein Handy stört

Zwei Diskussionsrunden– Magnete– Webseite/Forum

Statistik: wer war da

Lichtquellen:SLAC, BNL, Diamond, ESRF, PSI, Australian synchroton, Spring8, SSRF

Spallationsquellen:PSI, SNS

Zyklotrons:allg.: NSCL, iThemba, Uppsala, RIKEN, IBAmed.: MGH, Orsay, HZB,

Sonstige:GSI, HIMAC, INFN, DaLinac, Siemens, CERN, Fermilab

Historischer Überblick: Hardy (ESRF)

Ausblick: Hardy (ESRF)

Ansprüche Spallation: PSI

Theorie und Programme: SNS

Theorie <-> echtes Leben

Trend formale Organisation: GSI

Trend formale Organisation: SLAC

Trend formale Organisation: CERN

Trend formale Organisation: BNL

Trend formale Organisation: NSCL

Automatisierung: Australien

Lichtquellen:SLAC, BNL, Diamond, ESRF, PSI, Australian synchroton, Spring8, SSRF

Spallationsquellen:PSI, SNS

Zyklotrons:allg.: NSCL, iThemba, Uppsala, RIKEN, IBAmed.: MGH, Orsay, HZB,

Sonstige:GSI, HIMAC, INFN, DaLinac, Siemens, CERN, Fermilab

Kontrollsystem: ESRF

e_log: INFN

e_log: http://midas.psi.ch/elog

RF verbessert: RIKEN Ringzyklotron

Erreicht durch

-Vakuum verbessert

-CW – konditionieren…

RF verbessert: DALINAC

Temp.sensor auf RF Regelkarte

Diagnose: DiamondRemotely Controlled, Mobile, Thermal Imaging Platform

fehlende Diagnose: CERN

Wartung auch für Ersatzteile: Spring 8

Probleme durch Kleinigkeiten: SINAP

Probleme durch Kleinigkeiten: CERN

Umfrage: Magnetfehler

Stromausfälle: iThemba

Stromausfälle: Australien

med. Beschleuniger: MGH: >95%

med. Beschleuniger: Orsay

med. Beschleuniger: Siemens, prev. maintenance

med. Beschleuniger: IBA, Field Replaceable Unit

Reliability unter besonderen Umständen

Reliability unter besonderen Umständen

uptime: 94%

Zusammenfassung

Erfahrungsberichte aus der Praxis – nicht geschönt große Unterschiede zwischen den Beschleunigeranwendungen:

die Probleme sind jedoch bei allen ähnlich intensiver Austausch, sowohl in Podiumsdiskussionen

– Lüdeke - zentrale Datenbank für Reliability, andreas.luedeke@psi.ch – Spencer - http://slac.stanford.edu/pubs/slactns/tn04/slac-tn-09-001.pdf

als auch mit den Teilnehmern viele Ideen für zu Hause mitgebracht

Lichtquellen Kernphysik/Spallation

Med. Beschleuniger

Betriebszeit ~ 4500 h ~ 6000 h stark variierend

Uptime > 98 % > 90 % > 95 %

History

1977: start of cyclotron operation for nuclear physics (VICKSI)

1995 – 2006: Ionenstrahllabor ISL – laboratory for ion beam applications

– internal and external (~ 70%) users

– ion energy: eV < Eion< 800 MeV

– research areas:

• materials modification and ion-solid-interaction

• materials analysis

• medical applications

since 2007: accelerator operation for therapy purposes only

Accelerator Layout

2 x 14.5 GHz ECR sources on 150 kV platforms

RFQ 5.5 MV Van-de-Graaff

k = 132

16 dedicated target stations

95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 100

5

10

15

Do

wn

tim

e (

%)

Accelerator Performance

cyclotron in operation since 1977averaged downtime before 1995: 10 %

start of therapy

start of RFQ operation for users

Reduction of Downtime

step by step process

addressing all subsystems:sources, injectors, beam lines, cyclotron, control systempreventive maintenanceincreased redundancymodernisation improved diagnosisreduction of elements

Preventive Maintenance

regular belt change of Van-de-Graaff service of rotating parts cyclic change of spare power supplies used on HV terminal drying of SF6 gas

cleaning of isolators service on vacuum pumps: oil, bearings replacement of water tubes

Modernisation

new computers for control system replacement of old dipole power supplies exchange of shunt against transducer regulation in quadrupole

power supplies (gain in stability: factor 10) discrete rectifiers replaced by complete 3-phase modules replacement of main coil power supply of cyclotron

side effect: less energy consumption

Redundancy / Reduction of elements

smaller variety of pumps, vacuum gauges, power supplies…. whenever possible: spare parts for quick exchange

low intensity proton beams: no pre-bunching no water cooling of deflector plates in beam line dipoles

Improved Diagnostics

display of accelerator status

Improved Diagnostics

display of accelerator status 24 h charts

start of main magnet overshoot procedure

Improved Diagnostics

display of accelerator status 24 h charts beam stability programme

ISL Protons for Therapy (PT)

11/04: decision to close ISL at the end of 2006– Post-Docs and technical staff on temporary

positions left– people were transferred

to other departments– stop of investments

9/06: start of planning operation solely for PT

– reduced man-power(less beam-time)

– reduction of beam lines, cables…

– this step: almost completed

nevertheless:maintain reliability

Accelerator Performance

small number of beam time hours: major events have huge impact on statistics

95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 100

5

10

15

Do

wn

tim

e (

%) ~ 4500 hours/year

~ 1750 hours/year

changing ion species and energies

~ 15 target stations varying requirements on focusing

34 weeks/year 3 shifts a day (24/24)

H, 68 MeV–cyclotron fixed frequency–one NMR-probe/dipole

2 target stations, identical focusing

–1/4 of existing beam line system 12 therapy weeks/year 2 shift operation (6:00 -22:00) Thursday: start up and tuning Friday: quality control of accelerator weekend: standby* Monday-Friday: Therapy

ISL PT: Operation Comparison

*exceptions on weekends: - experiments- infants, requiring more than 4 sessions

PT: Reliability

availability 95 % in 20072/3 of downtime due to one major event: electrostatic injection

– preventive maintenance– replacement of Ta shields by Ti

(good experience in ECR source)– after one week: failure– fault of new ceramics ?– Ti shields (now Ta again)– delay of 2 days

uptime 2008: 98 %worst case: failure in electricity supply at 6:00 am

– delay of 2 hours

Accelerator Operation: Reliability

uptime 2009: 95 %1/3 of downtime again due to one major event: water leak in RF

– interruption of therapy week for the first time since 1998 (110 therapy weeks)

availability 2010: 95 %frequent drops in RFerror difficult to find: isolator problems on tube socket of anode power supply

Lessons Learned

turbo pumps on 60 % of rotational speed (standby mode) increases service intervals about factor 5

analysis of residual gas for water logging of electricity for failure analysis

cryo pumps on

cryo pumps off

Wish List

Uninteruptable Power supplies:– overall solution: too expensive in investment and man power– thus only for computers of control system

counter on frequently moved Faraday cups

14:47:12.00 14:47:12.50 14:47:13.00 14:47:13.50

140

150

160

170

180

190

200

210

220

230

240

Vo

ltag

e [V

]

time

V1 V2 V3

ISL PT: Installation of a Tandetron

further shortening of beam lines less rooms reduction of radiation safety easy and reliable operation:

– no moving parts– source on “ground potential”

installation:Apr. 07:purchased from BAM, start of dismantlingOct. 07:transfer to HMI, installation startsSep. 08: first beam from sourceOct. 08: first beam through tandetronMar. 09: first beam through cyclotronAug. 10: acceptance test finished, applied for licenceDec. 10: licence grantedJan. 11: first therapy with tandetron as injector

ISL PT: Installation of a Tandetron

start of tandetron beam tests: perfect short term stabilitymeasured on FC behind cyclotron

14:35 14:36 14:37 14:38 14:39 14:400

1

2

3

4

5

15

20

25

30

Std

. D

ev.

(%)

I F

CZ

1 (n

A)

14:45 14:50 14:55 15:00 15:05 15:10 15:1514.0

14.5

15.0

15.5

16.0

16.5

17.0

I F

C (

nA

) ISL PT: Installation of a Tandetron

start of tandetron beam tests: perfect short term stabilitybut long term stability unsatisfactory

ISL PT: Installation of a Tandetron

start of tandetron beam tests: long term stability unsatisfactory now: short and long term stability better than 5 %

21:00 01:00 05:00

1.95

2.00

2.05

2.10

stability_QS1!plot110407 JR 08.04.2011

I cu

p (

µA

)

Time (start 7. Apr. 2011)

Conclusion

12 therapy weeks per year past years: uptime at least 95 %

98 99 00 01 02 03 04 05 06 07 08 09 10 11

3

0

1

05

1

66

2

34

3

17

4

37

5

36

6

77

8

29

10

14

12

27

14

37

16

610

25

50

75

100

125

150

175

200

225

Pa

tie

nts

pe

r Y

ea

r

Conclusion

12 therapy weeks per year past years: uptime at least 95 % but: the finest hardware is useless without dedicated personnel

→ sincere thanks to all the people involved

Thank you for your attention!