workshop chamonix xiv shortcuts during installation and commissioning: risk and benefit h....

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

Workshop Chamonix XIV, 18.01.2005 2

Contents

• Overview of the cryogenic system

• Commissioning of the cryogenic sub-system (refrigeration system, DFBs, DSLs and QRL)

• Possible shortcuts

• Conclusions


Cryogenic overview


Point 8 as an example

Redundant systemsfor 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)


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


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


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


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


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


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


QRL commissioning

• Critical for magnet commissioning

• Tests:» Tests at factory

» Warm commissioning during and after installation

» Cold commissioning


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)


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


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)


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



• 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



• 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



• 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


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


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


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”


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.

workshop chamonix xiv shortcuts during installation and commissioning: risk and benefit h....

Documents

commissioning of qrl

qrl commissioning

lhc commissioning

commissioning phasesphase

cryogenic subsystems

qualified subsystems

lines simplified test

powering test