lav damage and repair – m. moulson (frascati) – photon veto wg – cern – 5 april 2011 damage...
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LAV damage and repair – M. Moulson (Frascati) – Photon Veto WG – CERN – 5 April 2011
Damage to A3 during transport
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10 blocks were broken during transport due to low temperatures
Minimum temperature on vessel 4∘C at 09:20 on 02 Dec.Most broken blocks on layers 0 and 4 (most accessible)List of blocks broken reconfirmed during A3 repair
LAV damage and repair – M. Moulson (Frascati) – Photon Veto WG – CERN – 5 April 2011
Summary of A3 repair mission
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20 Sun Transport of spare blocks from Frascati by car
21 Mon Initial setupECN3 crane out of service
22 Tue Setup under TCC8 craneRadioprotection incident
23 Wed No work – RP survey
24 Thu Performed repairs on layers 0 & 1
25 Fri Rotate vesselExperiment with repairs on layers 3 & 4
Work Package Assessment: https://edms.cern.ch/document/1113598
People:Franco Cassese (Naples)Matthew Moulson, Massimo Santoni, Tommaso Spadaro (Frascati)Tonio De Oliveira (CERN)
Schedule:
LAV damage and repair – M. Moulson (Frascati) – Photon Veto WG – CERN – 5 April 2011
A3 repair procedure
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General procedure:
1.Remove endcaps and rotate to vertical position, layer 0 up
2.Repair and test the 6 damaged blocks on layer 0
3.Move back to rotation stand and rotate into upside-down vertical position, layer 4 up
4.Repair and test the 4 damaged blocks on layers 3 & 4
5.Rotate vessel to horizontal position, replace endcaps and store
Repair of blocks and bananas:
1.Loosen signal, HV, LED cables by cutting cable ties on grille
2.Lift out damaged banana and rest on platform supported on adjacent banana
3.Unsolder signal/HV connections for damaged block only
4.Replace damaged block with spare and resolder connections
5.Reinstall banana in vessel
LAV damage and repair – M. Moulson (Frascati) – Photon Veto WG – CERN – 5 April 2011
Plans for A3 repair
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LAV damage and repair – M. Moulson (Frascati) – Photon Veto WG – CERN – 5 April 2011
TCC8 setup for repair of layers 0 & 1
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LAV damage and repair – M. Moulson (Frascati) – Photon Veto WG – CERN – 5 April 2011
Blocks replaced, layers 0 & 1
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Replaced by ME1640 Replaced by ME1983 Replaced by MD9878
Replaced by ME2446Replaced by ME3360Replaced by ME1909
0-4-2 0-4-0 0-5-2
0-7-0 0-7-1
0-1-0
LAV damage and repair – M. Moulson (Frascati) – Photon Veto WG – CERN – 5 April 2011
Static load testing for damaged blocks
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How likely are damaged blocks to detach?• 6 broken blocks removed from A3• 4 intact blocks with bad tubes deliberately
exposed to cold at Frascati
Testing in progress
ME05757 blocks (84 kg)
ME291810 blocks (120 kg)
Glue holds
Glass breaks
One reinforcement supports weight of block
LAV damage and repair – M. Moulson (Frascati) – Photon Veto WG – CERN – 5 April 2011
Scratched blocks, layers 0 & 1
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Seen as dark splotch in Feb examNot seen in Dec (probably overlooked)Removed for further investigation
Glass scratched at base of reinforcement plate, probably during cleaningScratch can evidently propagate as crack in glass!
1-7-0
LAV damage and repair – M. Moulson (Frascati) – Photon Veto WG – CERN – 5 April 2011
Scratched blocks, layers 0 & 1
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ME3141 (0-6-0)Taken inside vesselSimilar to ME3060Also removed to get
closer look
Clear evidence of scratch at base of reinforcement propagating as crack
LAV damage and repair – M. Moulson (Frascati) – Photon Veto WG – CERN – 5 April 2011
Testing of scratched blocks
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Now that we know what to look for, many more scratched blocks found
3 blocks analyzed at FrascatiME3060, ME3141 – type 11 from A3ME1305 – type 15 from A5
ME1305Vibration applied with loadNo crack propagation seen
ME3060Flaw not easily visible at startBecomes visible as load appliedNo hysteresis Two temperature cycles appliedTwo-corner break
ME3141Load applied for 10 daysTwo corner break (maybe temp?)
All blocks gradually loaded to 7 bricks (84 kg)
LAV damage and repair – M. Moulson (Frascati) – Photon Veto WG – CERN – 5 April 2011
Other repairs, layers 0 & 1
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Torn Tyvek replacedBlocks ME2157 (0-1-2), ME1862 (0-1-3)
Creased Tyvek replacedBlock ME3102 (0-7-0)*
Oil drops from TCC8 craneBlock ME2918 (0-4-2)*
Punctum dolensME2451 (1-6-3)broken during replacement of ME3060 (1-7-0)
LAV damage and repair – M. Moulson (Frascati) – Photon Veto WG – CERN – 5 April 2011
Setup for repair of layers 3 & 4
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Original idea to repair without access to cables essentially impossibleTo finish repairs, it will be necessary to have access to area underneath blocks
LAV damage and repair – M. Moulson (Frascati) – Photon Veto WG – CERN – 5 April 2011
A3 repair: Lessons learned
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Studies on broken and scratched blocks:Blocks are highly resistant to mechanical stressReinforcements do provide extensive safety marginScratches can cause cracks, esp. combined with thermal stressesAvoid scratching blocks during cleaning
Layers 3 & 4:Need access to cables – impossible to carry out repairs otherwise
ECN3 crane:Need remote controlNeed to fix oil drip problem
Residual radiation protection concerns in TCC8/ECN3
LAV damage and repair – M. Moulson (Frascati) – Photon Veto WG – CERN – 5 April 2011 15
TCC8
ECN3
Transport to CERN
Transport to Frascati
Frascati
911 upstairs