Superconductivity and Cryogenics at CERN! - S. Claudet (CERN, Geneva) LHC Cryogenics Operation
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Superconductivity and Cryogenics
at CERN!
S. Claudet (CERN, Geneva)
LHC Cryogenics Operation
With valuable input from L. Tavian & A. Perin for their study on
similar topic published March2010, EDMS 1063910
GW Powerlines Workshop 2011, IASS Berlin
Abstract
Superconductivity and associated cryogenics have been used
at CERN since the sixties, with a sharp rise in capacity and
size for the LEP200 project and more recently for the LHC.
The actual achievements for LHC will be presented, with the
emphasis on the approach used towards efficiency and
availability.
Perspectives for power distribution applications will be
proposed, considering operational constraints transposed to
long power lines.
GW Powerlines Workshop 2011, IASS Berlin 2/42 Superconductivity & Cryogenics at CERN
Outline
• Introduction to CERN and LHC Cryogenics
• Relevant hardware and key performance
• Operation, maintenance organisation and results so far
• Perspectives for superconducting power lines
• Summary
GW Powerlines Workshop 2011, IASS Berlin 3/42 Superconductivity & Cryogenics at CERN
CERN in brief
European Organization for Nuclear Research
Founded in 1954 Geneva
20 Member States + Associates
Annual budget: ! 900 MCHF
Below 2’500 staff
Over 10’000 users
p-p collisions
1034 cm-2.s-1
14 TeV
0.5 GJ stored energy
24 km of superconducting magnets @1.8 K, 8.33 T
GW Powerlines Workshop 2011, IASS Berlin 4/42 Superconductivity & Cryogenics at CERN
Overall layout of LHC and its detectors
! 100 m
Diameter 8.5 km
Slope 1.4 %
Geological stability and controlled environment
GW Powerlines Workshop 2011, IASS Berlin 5/42 Superconductivity & Cryogenics at CERN
Main reasons to superconducting
For accelerators in high energy physics
api t a l C ost
• Compactness through higher fields C
N o t really the
Ebeam = 0.3 . B . r Ebeam = E . L
case for
[Gev] [T] [m] [Gev] [MV/m] [m] power lines
at i n g Co st
• Saving energy Oper
l e a r p o t e n tial
Electromagnets: Acceleration cavities C
Resistive: Pinput ! Ebeam Pinput ! Rs.L.E2/w for
power lines
Superconducting: Pinput ! Pref Rs ! RBCS + Ro
RBCS ! (1/T) exp(-BTc/T)
GW Powerlines Workshop 2011, IASS Berlin 6/42 Superconductivity & Cryogenics at CERN
Layout of cryogenics
Pt 5
Pt 4 Pt 6
8 x 18kW @ 4.5 K
1’800 sc magnets
Pt 3 Cryoplant
24 km & 20 Distribution
kW @ 1.8 K Pt 7
Present Version
36’000 t @ 1.9K
130 t He inventory
Pt 2 Pt 8
LHC cryogenics is the largest, the Pt 1.8 Pt 1
longest and the most complex Cryogenic plant
cryogenic system worldwide
GW Powerlines Workshop 2011, IASS Berlin 7/42 Superconductivity & Cryogenics at CERN
Cryogenic architecture
Typical LHC even point
Odd point Even point Odd point
MP Storage MP Storage MP Storage
1.8 K New Existing 1.8 K
1 Refrigerator Refrigeration
Unit
4.5 K
Refrigerator
4.5 K
Refrigerator
Refrigeration
Unit
Surface
could keep Warm Warm Warm Warm
the helium Compressor
Station
Compressor
Station
Compressor
Station
Compressor
Station
inventory in
Upper
place, and Cold Box
Cold Box Surface
allow the
Shaft
Shaft
operation of
LHC at low Lower
Underground
Cavern
Cold Box
level Cold Cold
Compressor Compressor
box Interconnection
Interconnection Box
Box box
Tunnel
Distribution
Distribution Line
Line Distribution Line Line
Distribution
Magnet Cryostats, DFB, ACS Magnet Cryostats, DFB, ACS
LHC Sector (3.3 km) LHC Sector (3.3 km)
GW Powerlines Workshop 2011, IASS Berlin 8/42 Superconductivity & Cryogenics at CERN
Evolution of capacity with time
Equivalent cooling capacity at 4.5K, delivered by industry
180 LHC, ATLAS, CMS
160 LHC
140 Before LHC:
existing experience for design, safety,
LHC: 144 kW
120
kW @ 4.5 K
controls, operation, availability, …
100
LEP2+
80
ITER
LEP2
60
40 OMEGA, ALEPH,
BEBC, DELPHI,
20 ISR Low-Beta LEP Low-Beta Tevatron, RHIC, Jlab,
0 SNS, HERA, Tristan, !
1960 1970 1980 1990 2000
Year
We did not start from scratch!
GW Powerlines Workshop 2011, IASS Berlin 9/42 Superconductivity & Cryogenics at CERN
Evolution of length with time
Length of cryogenic distribution lines
4500
LHC
4000
3500
3000
LHC: 25 km
2500
[meters]
2000
1500
LEP2
1000
CERN made lines
500
0
1960 1970 1980 1990 2000 2010
From CERN home-made hardware to industry (+ support) for large projects
GW Powerlines Workshop 2011, IASS Berlin 10/42 Superconductivity & Cryogenics at CERNEvolution of Helium storage with time
Necessary Helium inventory to allow operation
300
Virtual Helium Inventory
250 Liquid
200 Gas @ 2 MPa
[tonnes]
150
100
50
0
IC
RA
AF
P2
)
C
n
SC
tro
LH
RH
LE
B
HE
(S
va
CE
Te
Losses of about 2% per month to be compensated
GW Powerlines Workshop 2011, IASS Berlin 11/42 Superconductivity & Cryogenics at CERNOutline
• Introduction to CERN and LHC Cryogenics
• Relevant hardware and key performance
• Operation, maintenance organisation and results so far
• Perspectives for superconducting power lines
• Summary
GW Powerlines Workshop 2011, IASS Berlin 12/42 Superconductivity & Cryogenics at CERNTesting the cryogenic sub-systems
Performance assessment of all sub-system (at least a
type test) before being connected to the next one
Point 8
Storage
Surface
QSCC QSCA QSCB QSCC
QSRA QSRB
Shaft
QURA
Cavern
QUIC
QURC QURC
Tunnel
Sector 7-8 Sector 8-1
Large impact of discussions with manufacturers for HW protection
settings: they want to protect, we want to operate …
GW Powerlines Workshop 2011, IASS Berlin 13/42 Superconductivity & Cryogenics at CERNLHC 18 kW @ 4.5 K Helium Refrigerator
Compressor stations
GW Powerlines Workshop 2011, IASS Berlin 14/42 Superconductivity & Cryogenics at CERNCompressor station of LHC 18 kW@ 4.5 K
Bldg: 15 x 45 X 9
Pinput : 4.5 MW
Cool: 500 m3/h
Noise: 105 dBA
GW Powerlines Workshop 2011, IASS Berlin 15/42 Superconductivity & Cryogenics at CERNLHC 18 kW @ 4.5 K Refrigerator
Process cycle for Air Liquide
LN2
Expansion Turbines
Heat Exchangers
GW Powerlines Workshop 2011, IASS Berlin 16/42 Superconductivity & Cryogenics at CERNCold Boxes of LHC 18 kW@ 4.5 K
Key components:
Expansion turbines on gas Bldg: 15 x 10 X 10
bearings, plate fin heat Pinput : 40 kW
exchangers, cryogenic Cool: 20 m3/h
valves, vacuum shell Noise: 85 dBA
GW Powerlines Workshop 2011, IASS Berlin 17/42 Superconductivity & Cryogenics at CERN18 kW @ 4.5 K Refrigerators performance
33 kW @ 50 K to 75 K - 23 kW @ 4.6 K to 20 K - 41 g/s liquefaction
500
400 400 COP
250W/W
C.O.P. [W/W @ 4.5K]
300
200 200
100 Carnot
Carnot
Limit
00
TORE RHIC TRISTAN CEBAF HERA LEP LHC
TORE HERA
SUPRA RHIC TRISTAN CEBAF LEP LHC
SUPRA
GW Powerlines Workshop 2011, IASS Berlin 18/42 Superconductivity & Cryogenics at CERNFirst cool-down of LHC sectors
300
First beams around LHC
Simultaneous Cryo
250
start/maintain
Short in
Temperature [K]
200 connection All sectors at
cryostats and nominal
150 repairs temperature
Open Days
100 UX85
Ph1
Christmas and water works
50
maintenance shut-down
Cool-down
0 time:
12- 10- 07- 04- 03- 31- 28- 26- 23- 21-Jul- 18- 15-
4’500
Nov-
t cold
Dec-
mass Jan- Feb- Mar- Mar- Apr- May- Jun- 2008 Aug- Sep-
from 10 wks
2007 2007to 2008 2008 2008 2008 2008 2008 2008 2008 2008
below 5 wks now
ARC56_MAGS_TTAVG.POSST
ARC67_MAGS_TTAVG.POSST
ARC78_MAGS_TTAVG.POSST
ARC34_MAGS_TTAVG.POSST
ARC81_MAGS_TTAVG.POSST
ARC12_MAGS_TTAVG.POSST
ARC23_MAGS_TTAVG.POSST
ARC45_MAGS_TTAVG.POSST
If 100 kg/m, 45km equals a LHC sector, with cool-down time in weeks !
GW Powerlines Workshop 2011, IASS Berlin 19/42 Superconductivity & Cryogenics at CERNPre-cooling to 80K with LN2
Cooldown to 80 K: 600 kW per sector with up to ~5 tons/h liquid nitrogen
200 10000
P18
180 P2 9000
P4
160 8000
LN2 deliveries per site
P6
LN2 deliveries for LHC [tons]
P8
140 7000
Total per day
120
Cumulated 6000
100 5000
80 4000
60 3000
40 2000
20 1000
0 0
01-Jan- 29-Jan- 26-Feb- 25-Mar- 22-Apr- 20-May- 17-Jun-
2008 2008 2008 2008 2008 2008 2008
Heavy logistics and manpower: (so far from 6h to 22h, 6 days/week)
- 2008: 500 trucks (20 tons) for 7 sectors in 5 months
- 2009: 400 trucks (20 tons) for 5 sectors in 3 months
GW Powerlines Workshop 2011, IASS Berlin 20/42 Superconductivity & Cryogenics at CERNInterconnections in LHC tunnel
Compulsory high level Quality Assurance !!!
65’000 electrical joints 40’000 cryogenic junctions
Induction-heated soldering Orbital TIG welding
Ultrasonic welding
Design issue,
Very low residual resistance to be cured 0.2% to 1% in-situ leaks Weld quality
in 2013
HV electrical insulation 19 left as “acceptable” Helium leaktightness
6 appeared (4 cured)
GW Powerlines Workshop 2011, IASS Berlin 21/42 Superconductivity & Cryogenics at CERNPresent LHC baseline (1/3)
LHC ARC: CRYOGENIC AND INSULATION VACUUM BASELINE DESIGN
Insulation Vacuum sectorization:
Magnet vacuum barriers Jumper vacuum barriers Cryogenic line vacuum barriers
QRL vacuum jacket
Spacing of vacuum barriers compatible with pressure
protection of helium pipes in case of degradation of
the insulation vacuum, and additional pumping ports
Magnet vacuum vessel
Q7R Q9R Q11R Q13R Q15R Q17R Q19R Q21R Q23R Q25R
available to mitigate leaks if necessary!
Q27R Q29R Q31R Q33R Q33L Q31L Q29L Q27L Q25L Q23L Q21L Q19L Q17L Q15L Q13L Q11L Q9L
Cold-mass sectorization:
Bus-bar plugs Safety relief valves Cooldown and fill valves
A B A B A B A B A B A C D A B A B A B A B A B A B A
Q7R Q9R Q11R Q13R Q15R Q17R Q19R Q21R Q23R Q25R Q27R Q29R Q31R Q33R Q33L Q31L Q29L Q27L Q25L Q23L Q21L Q19L Q17L Q15L Q13L Q11L Q9L Q7L
GW Powerlines Workshop 2011, IASS Berlin 22/42 Superconductivity & Cryogenics at CERNMain cryogenic line performance
Heat inleaks E+F B+C+D
[W] (50-75 K) (4-20 K)
Calculated 9850 593
9000 +/- 400 634 +/- 50
Measured
(~ 2.8 W/m) (~0.2 W/m) Best:
0.05 W/m
inner pipe
GW Powerlines Workshop 2011, IASS Berlin 23/42 Superconductivity & Cryogenics at CERNControl logic must handle long time delays
E
Density [g/l] Mass [kg] Time flight
C
C [3B, 5K] 118 3058 5 - 12h
B D [1.3, 8K] 8 467 1 - 4h
D
B [0.015, 4K] 0.18 29 4 - 12'
F
along 3.3 km sector
5.7
12 hours
5.6
5.5
5.4
Temperature
03R2_TT961
07R2_TT961
5.3
Slow propagation
13R2_TT961
21R2_TT961
5.2 29R2_TT961
of « warm bump »
33L3_TT961
25L3_TT961
5.1 17L3_TT961
09L3_TT961
along the sector 5
4.9
4.8
4.7
21-Apr-2010 22-Apr-2010 22-Apr-2010 23-Apr-2010
12:00 00:00 12:00 00:00
GW Powerlines Workshop 2011, IASS Berlin 24/42 Superconductivity & Cryogenics at CERNElectrical Feed Boxes
Connection to
magnets x 16
Vacuum equipment VAA
Current lead chimneys
2 per LHC Point
Sh
uff
lin
gm 6kA leads
od
u le 13kA leads
Hi
gh
cu
SHM/HCM rre Jumper cryo
nt
interconnect mo connection to QRL
du
le
13
k A& Supporting beam
6k
Al
ea
ds 6kA leads
Removable door 600A leads
HCM/LCM Lo
w
interconnect cu
rre
nt
mo
du
le
LHC: 3.4 MAmp
6k
A &6
00
Al
ea
ds
1.9K
4.5K
Global electrical protection system (quench detection) mandatory
GW Powerlines Workshop 2011, IASS Berlin 25/42 Superconductivity & Cryogenics at CERNElectrical feedbox with current leads
LSSL2 of the LHC
GW Powerlines Workshop 2011, IASS Berlin 26/42 Superconductivity & Cryogenics at CERNSuperconducting Links
A kind of power line built in low-load rigid cryogenic transfer line
Temperature of the 3 branches
76 m with 3 branches, 11 x 6 kA + 12 x 600 A
0.15 K
10 hours
517 m , 44 x 600A Hot spot
GW Powerlines Workshop 2011, IASS Berlin 27/42 Superconductivity & Cryogenics at CERNControls for LHC cryogenics
21300 AI, 7000 AO, 18400 DI, 4200 DO, 4000 analog control loops
Cryo instrumentation expert tool
Central Control Room Local Cryogenic
PVSS DS control room!
PVSS DS Sector
OWS OWS [1..x]
[1..x]
Return
Module!
FECs
(FESA)
RM sector 81
UNICOS
RM sector 78 RM sector 78
WFIP PROFIBUS DP
Networks (7) networks
PROFIBUS PA networks
More than 120
PLC for the
cryoplants and
the 8 sectors
TT, PT, LT, DI, EH CV
GW Powerlines Workshop 2011, IASS Berlin 28/42 Superconductivity & Cryogenics at CERNOutline
• Introduction to CERN and LHC Cryogenics
• Relevant hardware and key performance
• Operation, maintenance organisation and results so far
• Perspectives for superconducting power lines
• Summary
GW Powerlines Workshop 2011, IASS Berlin 29/42 Superconductivity & Cryogenics at CERNAffectations LHC Cryo CRG-OA
Structured alarms
LHC eLogbook
Cryo OP Procedures
Documentation …
Ing. OP référents
4 academic experts Cern Control Center: Monitoring on shift 24/7
4
Ing. production
Site management
Site control rooms: periodic checks, 1st line intervention
Opérateurs
12 Sites + Shifts
+ Industrial partner teams in local control rooms (! 15 personnes Serco)
High level recruitment, training (academic - on the job - shadowing),
certification for operation (10months), join & leave about to work
GW Powerlines Workshop 2011, IASS Berlin 30/42 Superconductivity & Cryogenics at CERNMaintenance
Operators
Simple adjustments foreseen by the component, equipment or
A installation supplier by the means of components that are
principles
accessible without disassembly and opening of the component.
and/or
The replacement of consumables that can be accessed safely
as bulbs, filters, oils, etc.
Contractor
The repair or maintenance by standard exchange of elements
B foreseen for this type of repair
and/or
Preventive Corrective Minor operations of preventive maintenance.
Contractor
The identification and diagnostics of the failure which may
Predictive Time C be followed by the replacement of components.
and/or
dependent If failure The global adjustment and calibration of the equipment/
component.
Contractor or CERN
Complex tasks of corrective and preventive maintenance,
D in particular the disassembly of a system, exchange and/or
repair of components, reassembly and adjustment of the
system, but it is excluding the rebuilding of components.
and/or
The replacement of an assembly of electrical components.
CERN
Extensive repair, renovation and rebuilding tasks.
E Rebuilding means in this context the manufacturing of
components on the basis of a manufacturing drawing
(examples are the manufacturing of a rotor screw, the rewinding
of a large motor winding and the manufacturing of a cooler).
Simply applying standardised methods!
GW Powerlines Workshop 2011, IASS Berlin 31/42 Superconductivity & Cryogenics at CERNSoftware tools Spares: 6’000 - Number of assets: 32’000 >1MCHF: 0 50k
LHCCryo Availability 2010
Based on LHC_Global_CryoMaintain signal per unit of time
100
For
Beams
90 All
included
80
70
60
Availability
50
Easyer for us with LHC being presently
40
commissioned with beams not yet nominal and
30 periodic scheduled technical stops
Powering tests
20 - LHC Operation: 6 periods of 6.5 weeks
- Technical stops: 6 x 0.5 wks (small corrections)
10
- Xmas break: 8-10 weeks (medium works)
0
25-Jan 22-Feb 22-Mar 19-Apr 17-May 14-Jun 12-Jul 9-Aug 6-Sep 4-Oct 1-Nov 29-Nov
Daily "Global LHC Cryo" weekly AVG Monthly AVG Scheduled Stops
GW Powerlines Workshop 2011, IASS Berlin 33/42 Superconductivity & Cryogenics at CERNLHCCryo Availability 2011
Based on LHC_Global_CryoMaintain signal per unit of time
100
90
80
70
60
Availability
50
40
30
20 Rather a very nice start for 2011
10 With availability not yet reliability!
0
24-Jan 21-Feb 21-Mar 18-Apr 16-May 13-Jun 11-Jul 8-Aug 5-Sep 3-Oct 31-Oct 28-Nov
Weekly 2010 Monthly 2010 Scheduled Stops Daily 2011 Weekly 2011 Monthly 2011
GW Powerlines Workshop 2011, IASS Berlin 34/42 Superconductivity & Cryogenics at CERNAvailability, key performance
2010
100%
90%
Target for
Global availability
100%
80%
95%
LHC
70%
operation
[8 sectors]
90%
60%
85% (2009)
50%
80%
97% 98% 99% 100%
40%
30% Target for HWC
20% (2008)
10%
0%
50% 60% 70% 80% 90% 100%
Individual
State of the art availability for a single
cryoplant: 99.5% with 12 weeks
GW Powerlines Workshop 2011, IASS Berlin maintenance
35/42 / 4 years (2+2+2+6)
Superconductivity & Cryogenics at CERNOutline
• Introduction to CERN and LHC Cryogenics
• Relevant hardware and key performance
• Operation, maintenance organisation and results so far
• Perspectives for superconducting power lines
• Summary
GW Powerlines Workshop 2011, IASS Berlin 36/42 Superconductivity & Cryogenics at CERNContext
50 km 50 km 50 km
Cryoplant
1000 km:
Cryoplant
10 plants
Thermal screen (return)
every
SC cable duct (supply) Hydraulic plug 100 km
Configuration of a long sc power line system is a tradeoff between:
– Minimised number of cryoplants to reduce capital costs, complexity and
increased operational efficiency. Large flow rate to be circulated would
require large diameter to match acceptable pressure drops, therefore
larger helium inventory
– Minimised dimensions of the cryogenic piping to ease installation and
limit the quantity of cryogenic fluids
Distribution over unprecedented distances (50km) to be engineered !
GW Powerlines Workshop 2011, IASS Berlin 37/42 Superconductivity & Cryogenics at CERNVery low heat loads long lines
SC line
SC line
50 km 50 km 50 km shield
Vac tank
Cryoplant Vac tank
Thermal screen (return) Cryoplant
supply
return
SC cable duct (supply) Hydraulic plug
Approx. 400 mm Approx. 400 mm
Heat loads distribution:
– Dominated so far by static heat ( x5 w.r.t dynamic loads from cable)
– 0.05 W/m considered as static heat on inner pipe, which is ultimate
achievement with rigid pipes welded every 12-18m …
– Obvious need to get hundreds meters prefabricated elements
(flexible or semi-rigid) to ease installation and Quality Assurance
– So far, these lines have a heat load x5 larger than considered
Significant progress required in this field !
GW Powerlines Workshop 2011, IASS Berlin 38/42 Superconductivity & Cryogenics at CERNSectorisation and altitudes
Effects linked with change of altitude:
– Pressure difference (Ro.g.z) due to gravity (1.2 bar for 100m for LHe)
– Temperature difference (g.z) due to increased enthalpy (10% for 100m)
=> Usual turnaround implies re-coolers with valves, instrumentation …
Re-cooler Re-cooler Re-cooler
sc line
Pro/Cons associated with sectorisation:
– Increased complexity
+ Pressure protection: Safety valves (helium pipes and insulation vacuum)
+ Re-cooling time: Significant gain as each loop will be treated in parrallel
Dedicated engineering required to address these serious physical and technical
GW Powerlines Workshop 2011, IASS Berlin issues ! 39/42 Superconductivity & Cryogenics at CERNCryoplant efficiency & availability
Efficiency Availability Product
Conventional 0.97 0.99 0.96
Superconducting 0.995 0.95 0.945
sc “dreams” 0.99 0.99 0.98
Obvious efforts to be made on global availability:
– Not realistic to consider 15 days of downtime + maintenance per year!
– Obvious need of redundancy for cooling capacity, implying an
interconnection box between cryoplants and power lines, and potentially
a loss of efficiency (hot running spare for automatic switch!)
– Direct impact on investment costs !
Dedicated engineering required to address these serious global issues !
GW Powerlines Workshop 2011, IASS Berlin 40/42 Superconductivity & Cryogenics at CERNSummary
• LHC cryogenics is the largest, the longest and the most complex
cryogenic system worldwide. We could achieve a reasonable availability
(around 95%) so far with beams. This demonstrates that there are no
big issues in concept, technology or global approach for operation,
within LHC environment, schedule and boundary conditions.
• If one could think of applying such technology to GW power lines of
1’000km long, some efforts should be invested in:
– Very-low heat leaks cable in flexible line design of several 100m modules
– Sectorisation over long distance and acceptance of moderate altitude variations
– Assembly and safety valve concept for reliability in outdoor environment
– Cryoplant reliability (and efficiency)
• For the time being, we have difficulties to apply this concept with
significant altitude changes (1000m) and in no-man’s land areas …
GW Powerlines Workshop 2011, IASS Berlin 41/42 Superconductivity & Cryogenics at CERNSummary
Yes at CERN with specific efforts
(at least our experience)
Why not, at least for crowded
areas, but availability and practical
application to be checked
A real challenge with physical and
practical constraints !
GW Powerlines Workshop 2011, IASS Berlin 42/42 Superconductivity & Cryogenics at CERNYou can also read
