Transcript LHC

Operation of the LHC Cryogenics system
and
interface with beam & machine operation
S. Claudet (CERN, Geneva)
on behalf of the “Cryogenics Group”
Technology Department
Workshop Accelerator Operation 2012, SLAC
Outline
• Introduction to LHC Cryogenics
• Operation, organisation and results
• Availability and interaction with beam operations
• Summary
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LHC Cryogenics, interface with beam operation
LHC accelerator
p-p collision 1034 cm-2.s-1, 14 TeV, 0.5 GJ stored energy
Machine operation
Technology
24 km of superconducting magnets @1.8 K, 8.33 T
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LHC Cryogenics, interface with beam operation
Layout of LHC cryogenics
Pt5
Pt4
Pt6
8 x 18kW @ 4.5 K
1’800 sc magnets
Cry
plan&
t Dis
tion
24 okm
20 trib
kWu@
1.8 K Pt7
Present Version
36’000 t @ 1.9K
Pt3
130 t He inventory
Magnets
Pt2
LHC cryogenics is the largest, the
longest and the most complex
cryogenic system worldwide
Workshop Accelerator Operation 2012, SLAC
Pt8
Distribution
Pt1.8
Pt1
Cr yogenicplant
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LHC Cryogenics, interface with beam operation
How does it compare ?
180
LHC, ATLAS, CMS
160
LHC
kW @ 4 .5 K
120
L H C : 14 4 k W
Before LHC:
existing experience for design, safety,
controls, operation, availability, …
140
100
LEP2+
80
ITER
LEP2
60
40
20
OMEGA,
ALEPH,
BEBC,
DELPHI,
ISR Low-Beta
LEP Low-Beta
Tevatron, RHIC, Jlab,
SNS, HERA, Tristan, …
0
1960
1970
1980
1990
We did not start from scratch!
Year
Workshop Accelerator Operation 2012, SLAC
2000
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LHC Cryogenics, interface with beam operation
LHC compressor station (x8)
4.2MW input power
Bldg: 15m x 25m
Oil/Helium Coolers
Workshop Accelerator Operation 2012, SLAC
Compressors
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Motors
LHC Cryogenics, interface with beam operation
18 kW @ 4.5 K Refrigerators (x8)
33 kW @ 50 K to 75 K - 23 kW @ 4.6 K to 20 K - 41 g/s liquefaction
LHe: 3’600 l/h
4m diam, 20m long, 100tons
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LHC Cryogenics, interface with beam operation
Cold under
vacuum
300 K under
atmosphere
1.8K Units with cold compressors (x8)
Cold Compressor
Active
magnetic
bearings
3-phase induction
Electrical motor
(rotational speed:
200
to 800
700Hz)
Hz)
200 to
125 g/s GHe from 15 mbar
to P atm with 3 or 4 stages
Fixed-vane
diffuser
Outlet
Spiral volute
Pressure ratio
2 to 4
Axial-centrifugal
Impeller (3D)
Inlet
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LHC Cryogenics, interface with beam operation
Electrical feed boxes for current leads
48 Boxes, 1200 leads
LSSL2 of the LHC
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LHC Cryogenics, interface with beam operation
One LHC sector: production-distribution-magnets
Total for 8 sectors:
Compressors: 64
Turbines:
74
Cold Comp.: 28
Leads:
1’200
I/O signals: 60’000
PID loops: 4’000
• Extremely large installed cooling capacity
• Complexity associated with 1.8K units
• Extremely large distribution system
=> Recovery from failures can last from few
minutes to 20 hrs, exceptionally 2-3 days
x 13.5
From LHC Magnet String test
3.3km
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LHC Cryogenics, interface with beam operation
Interfaces: follow-up electrical perturbations
EL perturbations and their impact on our LHC Cryo system
Electrical systems recover in ms
Cooling systems recover in min
Cryo
systems recover in hrs
=> A big incentive to be as tolerante to glitches as possible
Duration
[ms]
Voltage
change
[%]
Typical tolerance envelope
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LHC Cryogenics, interface with beam operation
Main reasons to superconducting
For accelerators in high energy physics
• Compactness through higher fields
Ebeam ≈ 0.3 . B . r
[Gev]
[T] [m]
Ebeam ≈ E . L
[Gev]
[MV/m] [m]
Be sure that at design stage, working at higher temperature was
considered, but not selected to maximise LHC beam energy
=> Cryogenic systems takes longer to recover from failures than
conventional ones (but we work on it!)
• Saving operating energy
Electromagnets:
Resistive:
Pinput ≈ Ebeam
Superconducting: Pinput ≈ Pref
Workshop Accelerator Operation 2012, SLAC
Acceleration cavities
Pinput ≈ Rs.L.E2/w
Rs ≈ RBCS + Ro
RBCS ≈ (1/T) exp(-BTc/T)
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LHC Cryogenics, interface with beam operation
Interactions between LHC systems
Powering OK
or interlock
Static and Dynamic
heat loads
Workshop Accelerator Operation 2012, SLAC
Beam related
Dynamic heat loads
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LHC Cryogenics, interface with beam operation
Outline
• Introduction to LHC Cryogenics
• Operation, organisation and results
• Availability and interaction with beam operations
• Summary
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LHC Cryogenics, interface with beam operation
Key factors for operation
• Equipment architecture:
– Central liquefier to intermediate buffer, distribution decoupled
– Cooling capacity production in line with demands
On-call adapted
• Type of operation
–
–
–
–
Transients (cool-down / warm-up) or various recovery
Alarm monitoring, simple reset actions, calling for experts
Detection of process degradation and curing action
HW checks and preventive treatment of slow evolving problems
• Frequency of required actions:
LHC: A huge and complex system
without significant buffer and
frequent operator actions required
– Once per month, once per week
– Once per 1-2 days
Workshop Accelerator Operation 2012, SLAC
Dedicated 24/7 required so far !!!
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LHC Cryogenics, interface with beam operation
Structure - Coordination - Outils
Operation Detect.
Operation Accel.
Methods - Logistics
Instrum-Cryolab
Electricity-Controls
Mechanics
Management
Coordinations:
• Team Leaders + Management (1/wk)
• Performance panel
(1/2wks)
• Operation / Maintenance panel
• Methods & Tools panel
Tools (web interface DB oracle):
• e-logboog operation for any change of configuration (wanted or not) or observation
and diagnostic request
• Diagnostic tables, work-orders, intervention reports
• Asset & spares management, intervention procedures
• Maintenance plan
• Scheduling
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LHC Cryogenics, interface with beam operation
Staff & team evolution
People should be able to quit, newcomers should be integrated
• High level requirements for recruitment (Bachelor & Masters)
• Formalised induction process:
Academic training - On the job training - Shadow shifts
=> Certification after ≈ 10 months as shift operator (alone!)
• Senior operator (>3 yrs):
Able with all sub-systems, ability to optimise production-needs-time
• Certification diploma:
Written - Site - Simulator - Improvement study (report + presentation)
• If selected for indefinite contract:
– Operation for 5 to 10 years
– Ability to become “production Eng.” as site responsible
– Ability to switch to support teams or another activity at Cern
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LHC Cryogenics, interface with beam operation
Cryo operator in Cern Central Control room
Shift 24/7
Fixed displays
Tendancy curves (summary)
Process synoptics and orders
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LHC Cryogenics, interface with beam operation
Operation, indicators
Efficiency
Alarms Powering
Global availability
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LHC Cryogenics, interface with beam operation
Outline
• Introduction to LHC Cryogenics
• Operation, organisation and results
• Availability and interaction with beam operations
• Summary
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LHC Cryogenics, interface with beam operation
Availability: a signal Yes/No is required
T2 = Achieved up time during required time / Required time x 100 (operational availability)
CM
CS
SP
CS
CM
Cryo Maintain: Few important conditions checking integrity of HW,
with slow power abort in case this signal is lost (leading to beam dump!)
set-point
Cryo Start: set of conditions to allow powering of concerned sub-sector,
T2 indicator
w.r.t
EN 15341
CM
with no action if powering started (illustrates good stability of process)
CS CM
Sum CM 8 sectors:
Global availability
Possibility to treat thousands of channels in a structured way to match at best the LHC
powering sub-sectorisation and the cryo sub-sectorisation
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LHC Cryogenics, interface with beam operation
LHCCryo global availability 2012
Target 2012
95%
100
2011
2010
2009
90
80
A v a ila b ility
70
L7
TT891
60
- Excellent 1st part to TechSTop
- Heavy works done during
Technical Stop #1, and cabling
weakness caused difficult recovery
50
P4
P18 CCs
P4 oil
ice
40
2xP8
CCs
30
- Very moderate impact from High
Luminosity operation in 2012
20
SEU?
P8+R5
10
0
27-Feb
26-Mar
23-Apr
21-May
Scheduled Stops
Workshop Accelerator Operation 2012, SLAC
18-Jun
Daily 2012
16-Jul
Weekly 2012
13-Aug
10-Sep
8-Oct
5-Nov
3-Dec
Between TS 2012
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LHC Cryogenics, interface with beam operation
Performance and origin of downtine
Global availability as seen by LHC
during beam operation periods
LHCCryo - Average of 8 sectors
(Between TS)
0.5
100
P e rc e n t [% ]
98
2.66
3.51
96
94
5.21
3.5
1
0.5
4.20
Supply (EL, CV, IT)
Cryo
Cryo SEU
Users
92
0.66
2.46
94.5
90
88
Others according to relative ratio of their
average for the 8 sectors
91.47
Global availability
0.15
Evolution:
89.68
- 2010: Correcting early Cryo bugs
86
2010
2011
(260 days)
(271 days)
(137/290)
(Full days, Mondays & Fridays of
Technical Stops not counted here)
Workshop Accelerator Operation 2012, SLAC
- 2011: Adapting to SEU (corrected @Xmas)
- 2012: So far rewarding !!!
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LHC Cryogenics, interface with beam operation
Availability: from global to single plant
Considering 8 independent sectors
100%
2010-2011
80%
[ 8 se c to rs]
G lo b a l a v a ila b ility
90%
70%
60%
50%
40%
30%
20%
10%
0%
50%
60%
70%
80%
90%
100%
Individual
Single
sector and cryoplant
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LHC Cryogenics, interface with beam operation
Indicators: recovery categories & tendency
+ Better global control/tuning
Nb
(operation, instrumentation)
stops
- ! SEU !
150
• Less Cryo induced failures,
. (but 3 VERY LONG ones!)
- More Supply (EL) failures
- ! SEU !
125
100
+ No longer recurrent Cold
Compressors particular issues
(Leaks, electronics)
75
50
Cryo SEU
Cryo down
25
0
2010
2011
short(<8h)
From the books:
Immediate effect of
(good!) practice
Workshop Accelerator Operation 2012, SLAC
2010
2011
2010
Medium(8h-30h)
Annoying if frequent,
to be kept low with
moderate efforts
2011
Long (>30h)
Serious cases requiring
specific monitoring and
significant efforts
25/30
Nice tendency,
promising for
2012 or new
surprises to
come up?
LHC Cryogenics, interface with beam operation
Operation structure & approach
• 2007/2008 cool-down & HWC:
Control rooms: site - CCC- office
Per site, one experienced engineer with agreed minimum
protocol to guide a local team of operators, with help of support
teams (instrumentation, experts, controls)
• Since 2009 and operation with beam:
One operator in shift 24h/7d, more transverse structure
site/CernControlCenter, procedures & operation tools
• For machine controls (temperature, level, pressure):
Basic interlocks and simple PID loops with generic tools for fast
orders, now completed with automated sequences & procedures
• Indicators:
From temperature stability to daily availability
on-line cool-down curves to on-line cryo-status
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LHC Cryogenics, interface with beam operation
Power Consumption for LHC Cryogenics
45
Stop
Cryoplant
Installed power
40
Operation with 8 plants
P ow e r [MW]
in p u t
Power
35
30
25
20
Net gain ≈ 50 GW.h
per year
(3 MCHF / year !!!)
Gain
≈ 8MW
Tests
Cool
down
Cryo optimized power
(20% of
installed
power)
15
5
HWC
LHC physics
LHC physics
6200 h
6500 h
700 h
10
90% Cryo Availability
91% Cryo Availability
0
03-Jul-
02-Oct-
01-Jan-
02-Apr-
02-Jul-
01-Oct-
31-Dec-
01-Apr-
2009
2009
2010
2010
2010
2010
2010
2011
2009
Cryo unavailability
breakdown
Workshop Accelerator Operation 2012, SLAC
2010
1
3
5
Cryo
Cryo
01-Jul2011
2011
3
4
Utilities Utilities
3
Users or Beam
Users or Beam
27/30
30-Sep2011
Cryo
Utilitie
Users
LHC Cryogenics, interface with beam operation
Helium invenrory [tons]
Workshop Accelerator Operation 2012, SLAC
-0.15
-0.45
-0.05
-0.50
-0.22
3.63
3.68
4.4
4.18
4.44
4.23
4.44
4.74
4.65
Livraison camion He
TS1 -0.65 T
H e liu m L o s s es [to n s ]
-1.31
2.52
3.16
Total masse He 2012
-1.29
-0.35
-0.50
1.97
en tonne
-1.12
-1.25
-0.76
159
157
155
153
151
149
147
145
143
141
139
137
135
133
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125
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115
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12-nov.-12
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26-nov.-12
03-déc.-12
10-déc.-12
17-déc.-12
24-déc.-12
31-déc.-12
Helium inventory follow-up
Remplissage DEWAR
Transfert SM18
30
25
20
15
10
2010
28/30
Transfert CAST
Transfert CMS
6
Technical Stop
• Now < 30kg/day
• With 50kg/day in 2011 and
better control @Xmas, tendency
to be confirmed
• @50 CHF/kg
en tonne
- 50kg/day # 2’500 CHF/day
- 150
t # 7.5 MCHF
45
35
Tech Stop
0
5
4
3
2
40
1
Xmas
Operation
0
5
-1
2011
-2
LHC Cryogenics, interface with beam operation
Interfaces with Beam-OP
• HW signals:
– Cryo Start and Cryo Maintain towards Powering Interlock module
• SW panels:
– Cryo web page
• People in Control Room (LHC):
– 1 Eng in charge + 1 operator
– 1 Cryo operator
– 1 operator for technical infrastructure
Text zone
• Possible evolutions ?
– Closer discussions with Eng. In charge in case of cryo problem
– Other operators involved to help diagnostics/recovery
– No longer cryo operators at night (on call only)
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LHC Cryogenics, interface with beam operation
Summary
• LHC cryogenics is the largest, the longest and the most complex
cryogenic system worldwide. We could achieve a reasonable availablity
(> 90 %) so far with beams. This demonstrates that there are no big
issues in concept, technology or global approach for operation.
• Despite all our efforts, we had very hard time and lengthy
commissioning to learn how to tune all these sub-systems together
while permanently consolidating what was not conform. Experience has
been converted into automatism, procedures, tools, training
• Cryogenics operation is well integrated in central control room with LHC
main systems, but operated/supported independently (about 50 people)
• Maintenance is as well reaching an efficient preventive/corrective ratio,
with efforts to be made for non-standard cases. We have to prepare for
higher energies and intensities with continued gain in reliability !
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LHC Cryogenics, interface with beam operation