workshop chamonix xiv shortcuts during installation and commissioning: risk and benefit
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Workshop Chamonix XIV Shortcuts during installation and commissioning: risk and benefit. H. Gruehagen, G. Riddone on behalf of the AT/ACR group 18 January 2005. Contents. Overview of the cryogenic system Commissioning of the cryogenic sub-system (refrigeration system, DFBs, DSLs and QRL) - PowerPoint PPT PresentationTRANSCRIPT
Workshop Chamonix XIVWorkshop Chamonix XIV
Shortcuts during installation and Shortcuts during installation and commissioning: risk and benefitcommissioning: risk and benefit
H. Gruehagen, G. Riddone on behalf of the AT/ACR group
18 January 2005
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Contents
• Overview of the cryogenic system
• Commissioning of the cryogenic sub-system (refrigeration system, DFBs, DSLs and QRL)
• Possible shortcuts
• Conclusions
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Cryogenic overview
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Point 8 as an exampleRedundant systems
for sector commissioning (upon QULA/ex-LEP ref.
completion) (no redundancy for sector 2-3)
Superconductinglink (DSL)
4.5 K refrigerator
1.8 K refrigerator
Cryogenic Inter-connection box(QUI)
Cryogenic Ring Line (QRL)
Electrical feed Boxed (DFB)
Local transfer Lines (QUL)
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Cryogenic sub-system commissioning
• Individual components and sub-systems are manufactured in industry
• After delivery and installation at CERN each sub-system is individually commissioned
• The commissioned and qualified sub-systems are then used in a cascade way to commission dependent sub-systems
• The collective behavior of the cryogenic sub-systems is progressively tested and overall process established
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Commissioning phases
• Phase 1: » storage» new and existing 4.5 K refrigerators» cryogenic interconnection box » 1.8 K refrigerator» transfer lines (vertical and local)
• Phase 2» QRL
• Phase 3» QRL + DFBs + DSLs + magnets: global pressure test
Ready for sector commissioning
Refrigeration system
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Refrigerator system /1• New 4.5 K refrigerators: all 4 units installed and
commissioned» Capacity and transient test performed» Used for commissioning of QUI, QURC, QRL and magnets» Very valuable experience gained when testing sub-
systems together in Point 8 (QSRB, QUI, QURC)
• Ex-LEP 4.5 K refrigerators» Possibility to use it for commissioning of QRL*» Compressor station upgraded and tested in 1998» Cold box upgrade foreseen mi-2005 to mi-2006» Functionality test foreseen (2-3 weeks)» Critical for LHC operation, redundant for LHC
commissioning (except sector 2-3)
* 1 refrigerator cannot serve the two adjacent sectors in different operation modes
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Refrigerator system /2
• 1.8 K Refrigerators» Not used for QRL commissioning, critical for
magnet testing» Pre-series already capacity tested» Foreseen tests of all 8 units after installation» Test of first unit underground already started
• Cryogenic interconnection box » Used for the QRL» Installed at P8, P2, P4, P6 and tested at P8» P8: consolidation under way» Critical for commissioning and LHC operation
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Refrigeration system /3
• Storage» Completely installed and tested
• QPLB (Vertical transfer lines)» Needed for the QRL» First two (of four) lines commissioned and accepted. Last
two lines simplified test with positive impact on schedule and resources.
• QULs (Local Transfer lines)» Will be needed for the sector 2-3. For other sectors, could
be used for the QRL upon completion of QULA/QURA/QSRA (end 2005 – mid 2006)
» First unit tested. Design validated» Requires adjacent components to be installed, and will be
commissioned together with them
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Electrical Feed-boxes (DFB) and Superconducting links (DSL)
» Critical for magnet powering» Cannot be tested in situ prior to magnet tests
• DFB» See presentation of A. Perin
• DSL» Cannot be completely tested without the DFBL and the
magnets» Type test (mechanical and thermal) foreseen in SM18 of
30 m of the line. Powering test requested by EEWG.» Type test to be done in parallel with installation, no
impact on schedule
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QRL commissioning
• Critical for magnet commissioning
• Tests:» Tests at factory
» Warm commissioning during and after installation
» Cold commissioning
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QRL / Tests at factory
QRL Elements (~300 / sector)
Leak test of individual circuits (RT)
Global leak test (RT)
Pressure test (RT)
N2 cooldown
Pipe elements (1) 100 % (B+F) 100 % (MWP(2)) at the beginning, then digressive
= =
Fixed points 100 % 100 % 100 % =Service modules 100 % 100 % 100 % 10 %
Steps/elbows 100 % 100 % 100 % =
(1): absence of penetrating welds(2): MWP, maximal working pressure (e.g. 16.5 bar for header C)
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QRL / Warm commissioning
QUI
A B C D E F G H I
EACH SUB-SECTORHe leak test after installation of each sub-sector: detection of warm leaks
SECTORCombined pressure and leak test: validation of the mechanical integrity at warm condition
- No cryogenic sectorisation - Vacuum sectorisation 8 vacuum barriers, 9 vacuum insulation sub-sectors
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QRL / Cold commissioning• Cold commissioning baseline: 8 weeks [12 for
the fist sector]» cool down, » thermal cycles, » heat inleaks
• Validation of: » mechanical design (cold leaks)» thermal design (heat inleaks)» instrumentation and valves (functionality)
• QRL design» Standard design: QRL in the straight part of the tunnel
(same design for all the 8 sectors)» Special design: QRL in the “Junction region (about 70-80
m)”, from the QUI to the straight part of the tunnel (each JR is unique)
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QRL / Possible shortcuts
• Helium leak test of the sub-sector» Allocated time: 3 weeks for each sub-sector, done
in parallel to the installation of other sub-sectors» Reason of the test: detection of warm leaks, » Benefit of skipping the test: None, no impact on
the schedule of the QRL installation» Risks if the test is skipped: detection of leaks
during combined pressure and leak tests, when magnets are already transported
» Repair if the test is skipped: leak detection in situ, magnet removal, opening of interconnections, repair (if leak is in interconnection) or replacement of the faulty element
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QRL / Possible shortcuts
• Combined pressure and leak tests» Allocated time: 3 weeks » Reason of the test: validation of the QRL design
at warm condition, detection of warm leaks» This test CANNOT be skipped, it can be
postponed with large risks: detection of leaks during commissioning of magnets
» Repair: leak detection in situ, magnet removal, opening of interconnections, repair (if leak is in interconnection) or replacement of the faulty element
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QRL / Possible shortcuts• Cooldown and thermal cycles
» Allocated time: 2 days per cycle + 2-3 weeks for instrumentation commissioning
» Reason of the test: • mechanical validation at cold condition (differential
thermal contraction), • detection of cold leaks (quality of welds) • commissioning of the instrumentation of cold condition
» Benefit of skipping the test: Shorter QRL commissioning, at least one cycle is mandatory
» Risks if the test is skipped: detection of leaks during sector commissioning, longer instrumentation commissioning during magnet commissioning
» Repair: leak detection in situ, magnet removal, opening of interconnections, repair (if leak is in interconnection) or replacement of the faulty element
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QRL / Possible shortcuts• Heat inleaks measurements
» Allocated time: about 2-3 weeks per test (very difficult to estimate due to the unknown stabilization time)
» Reason of the test: validation of the thermal design
» Benefit of skipping the test: Shorter QRL commissioning (gain: about 4-5 weeks per sector)
» Risks if the test is skipped: higher heat inleaks during sector commissioning, reason (QRL and magnets) cannot be easily identified (cold spots help)
» Repair: very difficult to add refrigeration capacity
Distribution of heat loads (ultimate operation)
0%
20%
40%
60%
80%
100%
50-75 K[W]
4.6-20K [W]
4.5 K[W]
1.9 KLHe [W]
1.9 KGHe[W]
4 K VLP[W]
QRL Magnets
23 kW 11 W 320 W
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Conclusions / Refrigerator Systems
• All tests foreseen can be done without impact on the installation and test of the magnet system
• Valuable experience will be gained through these tests» Training of operation team» Definition of automatic procedures for connection of sub-
systems» Identification of weak points
• All of which will make us gain time during future LHC commissioning
• Operational resources can be spared by skipping test, but valuable experience and training will be lostTest should be done as foreseen
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Conclusions / DFBs and DSLs
• DFBs: see presentation A. Perin• DSLs:
» Type test to be done in parallel with installation, » No impact on schedule
Type test should be kept to verify design
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Conclusions / QRL
• He leaktightness of the sub-sector should be kept (no schedule impact on the QRL installation)
• Combined pressure and leak test: cannot be skipped, can be postponed with large risks
• Cooldown/thermal cycles:» At least one thermal cycle per sector (quick test)» Several thermal cycles (6-7) recommended for
sectors with “old” production and might be skipped for sectors with only “new production”
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Conclusions / QRL• Heat inleaks measurements
» First sector (8-1): the full sector will be measured (old and new production)
» Sector 7-8: • heat inleaks will be measured on a portion of QRL (subsectors A,
B,…), needed a dedicated return box, scaling to rest of the sector might be difficult as sub-sector A is not standard
• Full sector measurement will be performed if partial measurement reveals higher heat inleaks than specified
» Other sectors: measurement on a portion of QRL will not be possible with current AL installation sequence, measurement of at least one full sector with only new production is highly recommended
» If measurements are skipped: • Critical headers: B and F (contribution from headers C and D are
negligible with respect to the dynamic loads) :• Header F (41% of total heat load): cold spots might be a reason
for higher heat inleaks• Header B (89 % of total heat load, factor 2 margin in ultimate
operation): measurements are still possible with magnets.