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Update on risk matrices for LHC Update on risk matrices for LHC

Update on risk matrices for LHC - PowerPoint Presentation

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Update on risk matrices for LHC - PPT Presentation

How to define How to use T CartierMichaud Andrea Apollonio Milan Ashwin Vekaria Miriam Ruth Blumenschein Jan Uythoven Risk matrices of LHC Defining acceptable failures rate wrt severity recovery time ID: 778194

lhc risk years hours risk lhc hours years recovery matric year month week matrices day 250 type faults duration

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Slide1

Slide2

Update on risk matrices for LHCHow to define ?How to use ?

T.

Cartier-Michaud, Andrea Apollonio, Milan Ashwin Vekaria,

Miriam Ruth Blumenschein, Jan Uythoven

Slide3

Risk matrices of LHC

Defining acceptable

failures rate w.r.t. severity / recovery time

:

Risk matric of LHC

LHC

risk

matrix

Recovery

year

month

week

day

hours

minutes

S7

S6

S5

S4

S3

S2

S1

Frequency

1 / hour

1 / day

1 / week

1 / month

1 / year

1 / 10

years

1 / 100 years

1 / 1000 years

Slide4

Risk matrices of LHC

Defining acceptable

failures rate w.r.t. severity / recovery time:

Respecting this matrix implies

At most 15% of “recovery time”

It does not directly translate into availability

Recovery implies turnaround ~> lost physics ?

Risk matric of LHC

Type of stop

Total

duration [days]

Percentage vs

op

Minutes type

250 days x 1/day x 15 minutes = 2.6

2.6/250 ~= 1%

Hours type

36 weeks x 1/week x 5 hours = 7.5

7.5/250 ~= 3%

Day type

8 months x 1/month x 2 days = 16

16/250 ~= 6%

Week type

1 year x 1/year x 10 days = 10

10/250 ~= 4%

Month type

1 year x 1/ 10 years x 45 days = 4.5

4.5/250 ~= 2 %

Year type

1 years x 1/100 years x 250 days = 2.5

2.5/250 ~= 1%

Slide5

Using AFT (2017 and 2018)  distribution function of fault durations

1582 faults for 2097.56 hours  2100h / (2x6000h) ~= 17%

If a fault occurs in stable beam  recovery = fault duration + turnaround (~5 hours)

256 faults in stable beam 

(512.83 + 1280) + 1584.73 ~= 3400

hours of recovery ?

Risk matric of LHC

Background of risk matrices

2017 & 2018

1326 faults

1584.73 hours

2017 & 2018256 faults

512.83 hours

Slide6

Risk matric of LHC

2017 & 2018

1326 faults

1584.73 hours

2017 & 2018

256 faults

512.83 hours

Slide7

Risk matrices of LHC

Different distributions would be acceptable ?

Risk matric of LHC

LHC

risk

matrix

Recovery

year

month

week

day

hours

minutes

S7

S6

S5

S4

S3

S2

S1

Frequency

1 / hour

1 / day

1 / week

1 / month

1 / year

1 / 10

years

1 / 100 years

1 / 1000 years

Slide8

Risk matrices of LHC

Defining acceptable

failures rate w.r.t. severity / recovery time:

Fancy results, WIP !

Need for a better measurement of turnaround

Extension of this study to 2016 ? 2015 ?

(faults of “week kind”)

Filtering by “filling scheme” ? (using past statistics to

predict future !?)

Risk matric of LHC

Type of stop

(with

turnaround of 5h)

number

Impact [hours]

Percentage vs

op

<

30 min

402

51.9

0.9

%

30 min < < 10h

366.5

1200.5

20

%

10 h < < 48h

22

411.8

6.9%

Slide9

Measured “background” = how far to the edge are we ?

Risk matric of LHC

Background of risk matrices

LHC

risk

matrix

Recovery

year

month

week

day

hours

minutes

S7

S6

S5

S4

S3

S2

S1

Frequency

1 / hour

1 / day

1 / week

1 / month

1 / year

???

1 / 10

years

1 / 100 years

???

1 / 1000 years

???

Slide10

Risk matric of LHC

Performance & Protection

Protection

Performance

Performance range:

Frequency ~< 1/month

Available statistics

Possible predictions

(

Isographe

,

AvailSim

)

Protection range:

Frequency >~ 1/years

Not so much statistics yet

Difficult to predict

“ double or nothing”

Slide11

Risk matric of LHC

How to use for new system ?

1) Study of schematics / reliability test / expert estimations

Failure rate / distribution function

2) Probability to fail (or not to fail) in a given period

Cumulative distribution function

Probability

that the failure X happens before

2 hours is less than or

equal to 10

%

3) How to set thresholds ?

Fixing x (duration) or T (probability threshold)

10% of failure for a given duration

Is unlikely to fail once before the given duration ?

90% of failure for a given duration

Is likely to fail at least once !

4) Maintenance strategy ? (time dependent failure rates)

 

 

 

 

 

Slide12

AFT should / could automatically provide “background” of risk matrices

Risk matrices could be an output of AWG reports

Need for a tuning of categories ?

How to predict the impact of a new system ?

If

Probability that the failure X happens before x is less

than or equal

to the threshold T

Depending on the back ground andon the threshold:

T = 10 % (unlikely)

x = 1 week

 it will happen every month

severity = S2

 fine

severity = S3

 maybe not fine !

slot already populated

 

Risk matric of LHC

Conclusion

(WIP)