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MICE Liquid Hydrogen system Post-R&D design review

MICE Liquid Hydrogen system Post-R&D design review. 15 th January 2013 S Watson. Purpose of this meeting. For each R&D outcome Describe existing situation and why a change has been recommended Discuss solutions

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MICE Liquid Hydrogen system Post-R&D design review

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  1. MICE Liquid Hydrogen systemPost-R&D design review 15th January 2013 S Watson

  2. Purpose of this meeting • For each R&D outcome • Describe existing situation and why a change has been recommended • Discuss solutions • Categorise into essential (prerequisite for Step IV) and desirable (post-Step IV) • Also to describe interaction of LH2 system with absorber and impact on system safety

  3. Time constraints • Global MICE schedule delayed – Step IV now 2014 • LH2 system cannot be fully commissioned until LH2 phase of Step IV (2015) • However, decision to carry out preliminary commissioning pre-Step IV (starting around Easter 2013) has been made: • System modifications • AFC interface hardware installation (transfer line etc) • Second R&D programme

  4. Relief circuit Current situation • Much discussed leak from relief lines into vacuum space arising from poorly specified relief valve and seemingly fault burst disk • Currently (and successfully) arrested with a check valve upstream of relief components Reason for modification • Check valve was allowed on the premise that it was only temporary • Check valve in current position stops vacuum poisoning system from operating

  5. Relief circuit Possible action • Move check valve downstream of vac poison connection • Modify/repair current components • Replace current components with vacuum-rated versions • Remove valve entirely and replace burst disk Considerations • Relief valve is very big and expensive • Work required to modify welded pipework is considerable

  6. Relief circuit

  7. InstrumentationBed pressure Current situation • Pressure gauge downstream of regulator • Used to control bed temperature Reason for modification • Bed control loop is essentially reactive as it can only respond once pressure drops below regulator setting; a gauge inside the bed would allow a proper feedback loop with pressure setpoint. • Once pressure is above regulator setting, there is no way of knowing what the pressure is i.e. how close to the relief valve pressure it is

  8. InstrumentationBed pressure Possible action • Leave as is • Move existing gauge to other side of regulator • Install new gauge Considerations • There is a broken dial gauge on the bed, upstream of the hand valve • Work required to modify welded pipework is considerable

  9. InstrumentationBed pressure

  10. InstrumentationBed flow in Current situation • Flow meter measures only flow out of bed into transfer line Reason for modification • Only way to measure progress of bed charging process is from the H2 bottle regulator pressure • Inaccurate and requires presence in MICE Hall • No way to measure flow during empty sequence • No direct indication of boil-off rate, although it is clear from the temperature and pressure readings when the sequence has finished or the absorption rate is slower than the boil-off

  11. InstrumentationBed flow in Possible action • Leave as is • Place flow meter in current pressure gauge (PG7) port • Install new flow meter • In H2 charge line • In gas panel pipework • Replace current flow meter with bi-directional version Considerations • Work required to modify welded pipework is considerable • Flow meter in charge line would only be useful during charge sequence, not empty sequence • Vice versa for replaced flow meter

  12. InstrumentationBed flow in

  13. Nitrogen flow Current situation • Two bottle packs with a change-over regulator situated on platform outside the Hall. Reason for modification • At a flow rate of 5l/min, each bottle pack lasts less than 2 weeks, meaning pack changing is required for run periods longer than a month. • Pack changing is awkward with current platform layout.

  14. Nitrogen flow Possible action • Leave as is • Install a LN2 Dewar to supply gas Considerations • Discussions regarding a Dewar are already progressing

  15. Nitrogen flow

  16. Viewing ports Current situation • Gas panel is completely opaque apart from one small viewing panel on the front Reason for modification • Critical hand valves are difficult to see from port • Other dial gauges (non-critical) not visible • Ice build-up on hydride bed not visible

  17. Viewing ports Possible action • Leave as is • Modify panels for increased visibility Considerations • None

  18. Viewing ports

  19. Magnetic field mitigation

  20. Control system • User interface (general improvements) • Unit consistency • Error messages and abort procedures • Development of EPICS monitoring, particularly alarm handler • Gas detection system improvements • Control room improvements

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