Modular Design for Cryogenic Hydrogen System in MICE

1. MICE Hydrogen System Design Tom Bradshaw Iouri Ivaniouchenkov Elwyn Baynham Columbia Meeting June 2003

2. MICE Cryogenic Components: • Decay Magnet – part of beam line – early installation and commissioning. Will have its own refrigerator • Implies 9 cryogenic modules: • 3 x Hydrogen absorber and Focusing coil pair • 2 x Spectrometer coils • 2 x Coupling coils • Scintillating fibre detector cryostat

3. MICE Stages Spring 2006 • Step 1 Decay magnet + Sci-Fi • Step 2 plus spectrometer • Step 3 plus spectrometer • Step 4 plus absorber/focus + hydrogen • Step 5 plus coupling absorber/focus + hydrogen • Step 6 plus coupling absorber/focus + hydrogen 2007 This implies a modular design for the absorber hydrogen system

4. Spectrometer Absorber/Focus Coupling Absorber/Focus Coupling Absorber/Focus Spectrometer Basic Layout Gas Store SciFi Detector Compressors 4K Return 14K 4K Cold box 14K Etc…. Decay Magnet Gate valve Refrigerator Powered valve Relief Valve

5. Hydrogen Design - Principles • What we are trying to do in the design is: • Make it truly failsafe and passive – no active intervention is required to get the hydrogen out of the system in the event of a problem. • Minimise the amount of hydrogen. • Minimise the volume that has to be considered to be a hydrogen area. • Make it modular to allow for staging. • Minimise interactions between the absorbers to keep the system simple and reduce consequential faults. • Prove we can do it for a neutrino factory

6. Hydrogen Design - Description Baseline Have gas tanks outside the experimental area piped in – Iouri will show layouts in talk tomorrow. Design is passive. Any emergency relief venting is through evacuated buffer volume – volume of this TBD but may just be a large diameter pipe. Helium purge may be preferable to nitrogen because of sludge and heat capacity issues. Have an igloo around each of the hydrogen modules vented through the roof – layouts TBD because it is complicated by several issues.

7. P P P P P Vent outside flame arrester Hydrogen tank Volume: 11 m3 Pressure > 0.1 bar H2 Detector H2 Detector H2 Detector P P P VP VP VP VP Hydrogen flow and safety system Version: 09/06/2003 He / N2 Purge system 14 K He from Cold box 18 K He to Compressor via Radiation shield P Fill valve X 2 X 2 H2 Gas bottle 1.7 bar 2.1 bar 12 litre Buffer tank Liquid level gauge Vent valve Vent outside flame arrester Vacuum Ventilation system Internal Window LH2 Absorber 70 K Safety window Vent valve LHe Heat exchanger Vent outside flame arrester Evacuated vent buffer tank Volume: Vacuum vessel Hydrogen module enclosure (igloo) Pressure relief valve Pressure regulator Non-return valve Pressure gauge Vacuum pump Valve Bursting disk

8. Hydrogen Storage – an Option • Hydrogen storage at STP will require three x 11m3 Vessels • Possibly manageable for MICE but not for a neutrino factory! • Alternative storage solutions being investigated – use of metal hydrides.

9. Energy research unit at RAL is conducting a small feasibility study Hydrogen storage • Commercially available – designs for automotive and fuel cell use • Absorbtion (exothermic) and release (endothermic) controlled by varying temperature • Large “compression” factor e.g. Ergenics ST-90 (pictured) 61x30x7.6 cm stores 2550 litres in a volume of 13.9 litres factor of 183 JSW Unit Ergenics Unit

10. Cooling power Requirements Baseline requirement is for : Absorbers 50W per module at 14K (He flow 2.4 g/s ΔT=4K) (MAC Estimate – any advance ?) Focus Coils 4K 14K Leads 5.2W 22W 0.18 g/s From M Greens paper but need new estimates based on current designs – Any thermal models ? In process of clarifying refrigeration requirements so input is needed !

11. END