MICE OsC – 22 nd June 2010 Liquid-hydrogen system and absorber M Hills T Bradshaw M Courthold S...

MICE OsC – 22nd June 2010

Liquid-hydrogen system and absorber

M HillsT BradshawM CourtholdS IshimotoW LauI MullacraneP Warburton


Contents

1. Introduction2. Latest progress on R&D system manufacture3. The system safety case4. Control system5. Hall infrastructure6. Integration with the AFC module7. Summary & plans for 2010/11


The Hydrogen Delivery System and Absorber

3

AFC Module(Tesla/Oxford/STFC)

Absorber (KEK/Mississippi)

Hydrogen Delivery System(STFC)


System Components


R&D System Manufacture (1)

Buffer Volume, Transfer Line and Test Cryostat all complete Gas Panel assembly well advanced Design of enclosure is being detailed

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R&D System Manufacture (2)

– Gas Panel manufacturing– Weld inspection and pipe cleaning complete– Final assembly of pipework underway– Flow meters (final item of instrumentation) procured and installed in the gas panel– Relief valves assembled into dedicated mounting frames

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Cryostat Cooldown Set-up


Cryostat Cooldown

Pre-cool with LN2


Safety Approach

– The system must tolerate two things going wrong simultaneously without becoming unsafe

– Design philosophy• Maintain separation of hydrogen and oxygen atmospheres• Avoid sources of ignition (a hydrogen-oxygen mixture only needs 19µJ to ignite)

– Standards• Dangerous Substances and Explosive Atmospheres Regulations (DSEAR). This is the

UK implementation of the EU ATEX User Directive.• IEC 61508 (Functional safety of electrical/electronic/programmable electronic

systems)

– Passive safety concept• Relief valves will open to return gas to the hydride bed or high level vents in the

event of a rapid pressure rise (e.g. due to loss of insulating vacuum). This happens independently of the control system.

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MICE Safety Considerations

The design of the MICE AFC module creates particular requirements:

– Thin windows on absorber have a design pressure of 1.7bara (they will be burst pressure tested to 4x this).

– Hydrogen system consequently operates at low pressure (relief valves set at 1.5bara; burst discs at 1.9bara)

– Rapid pressure rise could result from large liquid-to-gas expansion ratio of hydrogen (approx. 780/1)

– Pipework, Buffer Volume and relief valves are sized for total loss of vacuum in the AFC module

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DSEAR Zoning11

Test Cryostat (or AFC absorber vacuum space)

Gas Panel Enclosure Pump Enclosure Connecting ductwork

...are Zone 2.(“A place in which an

explosive atmosphere....is not likely to occur in normal operation, but, if it does occur, will persist for a short period only.”)

The MICE Hall is not


Control System (1)

Control Panel assembled with (almost) all components needed for He testing

Barriers provide intrinsic safety (<19µJ in the circuit) for all wiring except the heaters.

PLC programmed Temperature logging Valve control tested Example control sequence

tested

Heater control implemented

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PLC

Barriers

GP & Cryostat Connectors


Control System (2)

– Cryostat monitoring complete (almost)– Sequences for gas panel operation currently being written– Design work underway for ventilation system and vacuum

system control.


Control System Safety Functions

Only three functions of the control system identified as ‘safety critical’:I. Operation of the ventilation system on detection of a

hydrogen leakII. Shut-off PV20* if there is pressure rise in the cryostat

during operation.III. Interlock the Gas Panel Enclosure with system returning to

‘safe state’ on breaking of interlock

These will all be hard-wired and separate from the PLC.

[*This isolates the vacuum system.]

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UPS Requirements

Recent discussions held amongst the Hydrogen System team on the UPS requirements for the system

Document currently being drafted for submission to MICE Technical Board

Key conclusions– In the event of a mains failure:

• System will fail to its pre-defined ‘safe-state’• Instrumentation and valve position information should

continue to be available from the control system• The hydrogen detection system should continue to function

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Hall Infrastructure

To install the R&D system in the MICE Hall requires:– Bottle store– Vacuum system with roughing pumps sited externally– Ventilation system to exhaust any leak in Gas Panel, Buffer Volume or

Hydride Bed.

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Hall Infrastructure17

Relief lines

Ventilation ducts

Fans

Test Cryostat

Gas Panel Enclosures


Ventilation System

H2 vented during operation of relief valves is separate form ventilation system


Ventilation System

Basis of safety– Eliminate sources of ignition

ATEX rated fans– Fans are specified such that one fan only is capable of providing sufficient flow to exhaust all three

systems– An explosive atmosphere from a small leak in the gas panel would only persist for a matter of

minutes– Fans have been purchased and are ready to install.

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Vacuum System

– Dedicated pump enclosure to be sited on MICE Hall roof– Will house backing pumps

required for all 3 hydrogen systems

– Will also have capacity to house backing pumps required for other cooling channel modules

– Designated Hydrogen Zone 2 (same as Gas Panel Enclosures) for DSEAR purposes

– Turbo pumps for AFC modules’ safety vacuum shown on South Wall (must be behind magnetic shield wall)

Turbo pumps

Backing pump


– Located opposite the MLCR

– Virtually all preparation for rack installation complete: – room cleaned out– new door fitted– redundant pipes

removed– Cabinet support frames

installed– cable routes

established

Hydrogen Control Room


Integration with the AFC

– Working with Oxford, KEK and Tesla to ensure that the R&D system is compatible with the AFC module– Instrumentation – Process line connections

– Aim to test absorber in R&D test cryostat to check interfaces and instrumentation

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Absorber Instrumentation23


Schedule24


Summary and Future Plans– R&D System components complete with exception of Gas Panel and Enclosure; these

are due for installation at start of long ISIS shutdown.– Control system well advanced– Safety principles of system well established, but implementation and documentation of

these are still ongoing. Results from helium testing will be an important input to a pre-operation safety review.

– Design work underway for hall infrastructure requirements, but lots to do.– Need to continue to work closely with KEK, Oxford and Tesla to ensure compatibility with

AFC.– Aim to take advantage of the long ISIS shutdown and delays to the Spectrometer

Solenoids to install as much infrastructure as possible in the rest of this financial year.– Several tasks:

• Install R&D system components on south mezzanine• Build pumping enclosure and install vacuum system• Position fans, install ductwork and construct access platforms• Route vent lines outside hall• Install hydrogen detection system• Route cabling and install control racks in H2 Control Room

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MICE OsC – 22 nd June 2010 Liquid-hydrogen system and absorber M Hills T Bradshaw M Courthold S...

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