Workshop Chamonix XIV Shortcuts during installation and commissioning: risk and benefit

1. Workshop Chamonix XIVShortcuts during installation and commissioning: risk and benefit H. Gruehagen, G. Riddone on behalf of the AT/ACR group 18 January 2005

2. Contents • Overview of the cryogenic system • Commissioning of the cryogenic sub-system (refrigeration system, DFBs, DSLs and QRL) • Possible shortcuts • Conclusions

3. Cryogenic overview

4. Point 8 as an example 4.5 K refrigerator Cryogenic Inter- connection box (QUI) Redundant systems for sector commissioning (upon QULA/ex-LEP ref. completion) (no redundancy for sector 2-3) 1.8 K refrigerator Local transfer Lines (QUL) Cryogenic Ring Line (QRL) Superconducting link (DSL) Electrical feed Boxed (DFB)

5. 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

6. 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 Refrigeration system Ready for sector commissioning

7. 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

8. 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

9. 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

10. 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

11. QRL commissioning • Critical for magnet commissioning • Tests: • Tests at factory • Warm commissioning during and after installation • Cold commissioning

12. QRL / Tests at factory (1): absence of penetrating welds (2): MWP, maximal working pressure (e.g. 16.5 bar for header C)

13. QRL / Warm commissioning - No cryogenic sectorisation - Vacuum sectorisation 8 vacuum barriers,9 vacuum insulation sub-sectors EACH SUB-SECTOR He leak test after installation of each sub-sector: detection of warm leaks SECTOR Combined pressure and leak test: validation of the mechanical integrity at warm condition

14. 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)

15. 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

16. 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

17. 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

18. 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 23 kW 11 W 320 W

19. 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 lost Test should be done as foreseen

20. 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

21. 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”

22. 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.