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

Workshop Chamonix XIV, Contents Overview of the cryogenic system Commissioning of the cryogenic sub-system (refrigeration system, DFBs, DSLs and QRL) Possible shortcuts Conclusions

Workshop Chamonix XIV, Cryogenic overview

Workshop Chamonix XIV, Point 8 as an example Redundant systems for sector commissioning (upon QULA/ex-LEP ref. completion) (no redundancy for sector 2-3) Superconducting link (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)

Workshop Chamonix XIV, 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

Workshop Chamonix XIV, 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

Workshop Chamonix XIV, 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

Workshop Chamonix XIV, 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

Workshop Chamonix XIV, 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

Workshop Chamonix XIV, 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

Workshop Chamonix XIV, QRL commissioning Critical for magnet commissioning Tests: »Tests at factory »Warm commissioning during and after installation »Cold commissioning

Workshop Chamonix XIV, 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 % = Service modules 100 % 10 % Steps/elbows 100 % = (1): absence of penetrating welds (2): MWP, maximal working pressure (e.g bar for header C)

Workshop Chamonix XIV, QRL / Warm commissioning 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 - No cryogenic sectorisation - Vacuum sectorisation 8 vacuum barriers, 9 vacuum insulation sub- sectors

Workshop Chamonix XIV, 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 m)”, from the QUI to the straight part of the tunnel (each JR is unique)

Workshop Chamonix XIV, 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

Workshop Chamonix XIV, 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

Workshop Chamonix XIV, QRL / Possible shortcuts Cooldown and thermal cycles »Allocated time: 2 days per cycle 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

Workshop Chamonix XIV, 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 kW11 W320 W

Workshop Chamonix XIV, 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

Workshop Chamonix XIV, 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

Workshop Chamonix XIV, 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”

Workshop Chamonix XIV, 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.