QRL Leak Tests

the story so far……….

Paul Cruikshank on behalf of TE-VSC colleagues & AL4030 Consortium (S133)

1Paul Cruikshank TE/VSC - QRL Leak Tests - LS Committee, 24/5/2013

QRL Leak Tests in LS1

TE-VSC baseline objectives for QRL in LS1:

Collaborate with TE-CRG to repair known internal leak in S4-5, Helium to insulation vacuum - leak test all sectors, Air to insulation vacuum - leak test all sectors,

Reconfigure safety valves (ECR), Maintain fixed pumping equipment, Add additional pumping at subsector extremities (ECR),

Execute all tasks in shadow of SMACC planning.

2Paul Cruikshank TE/VSC - QRL Leak Tests - LS Committee, 24/5/2013

3

Courtesy K. Brodzinski

QRL Sector 4-5 header C tightness (recall) Problem appeared during Xmas break 2010/2011 (transient operation on LHC cryogenics). Deformation of QRICA corrugations were caused probably by thermal contraction of the compensator with condensed air blocked between the corrugations.air leak during operation → ice at compensator → fast desorption at warm-up > 40 K → expansion of header piping with ice present → damage to compensator → helium leakAdditional pumps were added by TE/VSC to continue operation in 2011, 2012 & 2013 up to LS1.

Source: S. Claudet, N.Veillet & AL

The aim of LS1 intervention is to replace the faulty

compensator(no magnet removal)

QRL Leak Tests – Observations May ‘13

6 of 8 QRL sectors measured,

5 new internal leaks confirmed: failure scenario appears same as S4-5; 2 existing internal leaks – S4-5, ssB, line C at Xmas 2010 – LS1 planned repair,

S7-8, ssA, line B at installation – no evolution, no action.

4Paul Cruikshank TE/VSC - QRL Leak Tests - LS Committee, 24/5/2013

QRL Leak Tests – to do immediately

Measure helium residuals in remaining 2 sectors – S1-2 & S5-6*.

For each internal leak:Confirm which header is leaking*,Longitudinally localise the helium leak under vacuum*,X-ray the suspect compensators (& others?),Check for air leaks on the vacuum vessel,Collate data & open NCRs.

Repair scenario(s) cannot be judged until above info is available.

*Several issues to overcome:cryo-lockout – 1% helium in headers, SMACC & magnet exchanges – headers cannot be pressurised, VSC instrumentation off at P7 – need mobile equipment,Co-activities in S5-6, S6-7 – SMACC,

5Paul Cruikshank TE/VSC - QRL Leak Tests - LS Committee, 24/5/2013

QRL Leaks – Proposed action plan

Agree the immediate actions with TE-CRG, EN-MME TE-MSC, others??

Integrate the new activities within master planning,

Execute the first repair as soon as possible to get feedback,

Identify mitigation measures that could be implemented during LS1 to protect the QRL during future operation/warm-up.

Report regularly to LSC on status.

Others……?

6Paul Cruikshank TE/VSC - QRL Leak Tests - LS Committee, 24/5/2013

QRL Leak Tests

Back-up slide

7Paul Cruikshank TE/VSC - QRL Leak Tests - LS Committee, 24/5/2013

LMC

SC - 16Feb'11

P. Cruikshank

Helium leak in QRL S45 subsector B- insulation vac evolution 23 December 2010

Pressure rise of 4 mbar in < 30 s

Suspect rapid desorption of air leak

~ 12 months of air leak at 1 E-2 mbar.l/s(280000 mbar.l of gas)

Cannot be attributed to cryosorbed helium(only ~ 100 mbar.l possible for this cryostat)

Subsector A

Subsector B

Subsector C

4 mbar

A-B

B-C

17:56 17:58

E-3 mbar

Pirani gauge readings

Prepared by P. Cruikshank