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MICE hydrogen review Commissioning, testing and operations.

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Presentation on theme: "MICE hydrogen review Commissioning, testing and operations."— Presentation transcript:

1 MICE hydrogen review Commissioning, testing and operations

2 Commissioning progress Transfer line manufactured and (roughly) fit-checked Vacuum line manufactured and fit-checked Absorber assembly – Window – absorber indium seals made – 2 MLI blankets applied

3 Testing Pre-sign off – Pressure test of absorber/window assembly* – Pressure test of newly installed pipework – Leak testing of overhauled relief circuit Pre-cryogenic operation – Leak test of modified sub-assemblies – Leak test of entire system – Turbo pump run-in test in isolation* – Test of gas detection system – Systematic test of valve and instrumentation operation Pre-experimental operation – Purge sequence* – Fill/empty cycle with helium* – Fill/empty cycle with hydrogen

4 Absorber system pressure test LH2 Vacuum Gas panel Two failure scenarios – Heat load into absorber, causing rapid boiling of LH2 through absorber relief line – Absorber window rupture, causing rapid boiling of LH2 predominantly through vacuum relief line AbsorberVacuum Both PRV Δ0.5 bar

5 Absorber system pressure test Heat load scenario – Significant heat can only feasibly come from a vacuum failure but… A safety window rupture would not cause a vacuum failure The surrounding vacuum vessels are substantial and unlikely to fail in a catastrophic way Small leaks, such as from seal degradation, would not result in rapid boil-off – Nevertheless, if such a vacuum failure were to occur, two estimates of the heat load into the LH2 were made: Film boiling i.e. maximum possible rate of heat transfer, regardless of ΔT ~ 19kW CERN paper with experimental data suggesting actual max heat transfer would be ~5kW – The latter figure was taken, doubled, and used to calculate a boil-off rate of kg/s – This was used to calculate a total pipe pressure drop from absorber to flame arrestor of 1.92 bar – PRV pressure is 1.5 bara. 1.1 x 1.25 x 1.5 bar = 2.06 bar, so a pressure test to this will be adequate. Note, windows have already been burst tested to above 8 bar

6 Absorber system pressure test Window failure scenario – Boiling rate from hydrogen spill would be considerable but has not been calculated with similar rigour to previous scenario (estimated at 0.12 kg/s in worst case) – However… Absorber and vacuum relief lines are effectively in parallel in this scenario, thus halving the pipe impedance There is a ‘bucket’ in the vacuum space to reduce the surface area which a spillage would be subject to The safety windows are 0.21mm at their thinnest point, as oppose to 0.18mm in the absorber windows The most likely window failure scenario is a crack or small breach, resulting in a much slower rate of heat transfer than in a full-scale rupture – MICE argues that testing to a higher pressure for the safety windows is unnecessary A burst test as per the absorber windows should be carried out however

7 Turbo pump Failures experienced – Pictured failure was seemingly random (and also not our pump!) – However, also had bearing problems due to excessive periods of inactivity Preventative maintenance programme – Gradual run in every 6 months – Pumps in storage for longer than 1 year sent to Leybold for bearing replacement – Project also has multiple spares now

8 System tests Helium purge – Pressurises with helium and pumps out three times – Tests operation of the gas panel, pumps, pressure gauges and control system Helium fill – no liquid – Uses the control valve to maintain helium pressure in the absorber vessel as it cools – Radiative heat load means the system will not reach 4.2K – Tests operation of the temperature sensors and cryocooler and provides an indication as to the cryogenic performance of the system as it cools down – Will have to be manually terminated Hydrogen vent – Replaces the old hydrogen empty sequence – Opens the vent line valve and switches the heater onto the absorber – won’t be particularly representative with cold helium but will still test the interlocks, valve operations etc

9 Milestones November December January February March April May June PRY installation 2015 FC contractual acceptance Absorber assembly FC#2 to MICE Hall Hydrogen safety review Vacuum and leak testing Pressure testing of absorber Cryogenic (helium) testing Hydrogen safety sign-off Cryogenic (hydrogen) testing Magnet testing begins

10 Operations General principle is that only designated ‘hydrogen experts’ interact with the system when hydrogen is present – Broadly speaking, this statement also stands during helium operations Hydrogen experts are: – Myself – Mike Courthold (part-time) – Phil Warburton (based at DL) – Mark Tucker (based at RAL) R&D tests took 4 weeks and required 14 people to staff 24/7 Same coverage will be required for: – Hydrogen commissioning – Active hydrogen sequences during operation – …but not for remainder of user runs – this will covered by on-call arrangements

11 Operations Run schedule handled by Steve Boyd (Warwick Uni)


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