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Cryogenic system for the MYRRHA linac

Cryogenic system for the MYRRHA linac. Nicolas Chevalier Tomas Junquera 20.10.2012. Part 1 Heat load budget and operating temperature. Static heat load. For MYRRHA, short cryomodules : 5 W/m at 2K 40 W/m at 40 K. Cavity dynamic heat load at 2K.

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Cryogenic system for the MYRRHA linac

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  1. Cryogenic system for the MYRRHA linac Nicolas Chevalier Tomas Junquera 20.10.2012

  2. Part 1 • Heatload budget and operating temperature

  3. Staticheatload • For MYRRHA, short cryomodules : • 5 W/m at 2K • 40 W/m at 40 K

  4. Cavitydynamicheatloadat 2K * Values from prototype cavities : Podlech et al., Bosotti et al. , Visentin et al., Olry et al.

  5. Coupler heatloads

  6. Coefficient of performance of cryoplant Close to XFEL or one LHC unit For MYRRHA, cryo power at 2K : ~14.2 kW Realistic goal : COP(2K) = 720 ; COP(4K)= 220 COP(2K)/COP(4K) = 3.3

  7. Overcapacity. Total heatload budget LHC « recipe » isapplied for safety factor : Overcapacity factor : 1.5  speed cool-down, use machine < 100 % performance Uncertainty factor : 1.25  imperfect Nb, electronloading, imperfect MLI wrapping etc. Overallmargin : 1.875 Overall power similar to : LHC (18 kW), JLAB (11 kW), XFEL (12 kW), 2 x SNS (2 x 6.4 kW)

  8. Heat load breakdown • Heatload distribution alonglinac: CH SPOKE LOW β ELL. HIGH β ELL. 150 W ~5.2 % 735 W ~27 % 635 W ~22 % 1360 W ~46% • heatloadisroughly25 % | 20 % | 50 % across the threesections • staticlosses~ ½ dynamicslosses smallcryomodule, lowfield • Dynamic range at 2K: Loadbeam on/beam off = (dynamic + static)/static Dynamic range = 2.8 LHC : 3 Important parameter for choice of refrigerationscheme (full cold compression or mixed compression)

  9. Temperatureoptimization of the MYRRHA linac COP decreaseswith T, RBCS increaseswith T  optimum of power consumption Optimal temperature: Broad minimum around 1.9-2 K

  10. Possible 4K operation of Spokecavities • 2K operation of Spokecavitiesis the reference design for now • 4K operationshouldbetested on prototype Spokecryomodule • In the design phase, pipes shouldbesized to allow 4K and 2K operation

  11. Part 2 Cryofluid distribution : valve box, transfer line and cool down characteristics

  12. Distributed or central subcoolingheatexchanger • Distributed : • 2K subcoolingisachieved in each valve box via heatexchanger • Low pressure vaporisreturnedat 5K • Central : • 2K subcoolingisachieved in a single central heatexchanger; • Subcooledsupercriticalheliumisdistributed in a separatetransfer line • Low pressure vaporisreturnedat 2K

  13. Subcoolingheatexchanger (SHX) specifications • LHC SHX canbeused if 1 SHX isused for 1 cryomodule • If 1 SHX feeds more than 1 cryomodule, SHX has to bemodified (up to 10 g/sec)

  14. 80K 3bar 40K 4 bar 6K 1.2 bar 4.5K 30 mbar Valve box : Spoke prototype Cryomodule 5K 3bar to conditioning TI TI CV SHX EV LI TI EV bypass POT TI TI JT SV RD vacuum barrier CD 4K FUV CV : conditioning valve EV : expansion valve CD : cooldown 4K FUV : JT : Joule-Thomson valve SHX : sucoolingheatexchanger SV : safety valve RD : rupture disk TI : temperature gauge LI : level gauge shield TI P LI 2K header TI TI TI TI beamline cavity coupler CC loop TI P TI TI

  15. 80K 3bar 40K 4 bar 6K 1.2 bar 4.5K 30 mbar Valve box : Spokeseries Cryomodule ? 5K 3bar TI TI All valves thatcanberemovedwithoutcompromising control shouldberemoved TI P LT TI TI TI P TI TI

  16. 80K 3bar 40K 4 bar 6K 1.2 bar 4.5K 30 mbar Valve box : Lowβelliptic Cryomodule 5K 3bar TI TI Similarscheme for highβellipticalisavailable TI EV JT P LT TI TI TI P TI TI

  17. Valve box premiminaryinventory

  18. 80K 3bar 40K 4 bar Alternative distribution scheme : 1 VB for 2 CM 6K 1.2 bar 4.5K 30 mbar 5K 3bar

  19. Advantages of 1VB-1CM and 1VB-2CM solutions Reference solution willbe 1 VB – 1 CM as itseems more straightforward. But 1 VB – 2CM couldbe more economical in terms of cost and space (e.g. ceiling)

  20. Operational modes, helium mass flows Wholelinac Per cryomodule

  21. Transfer line • Transfer line isassumed to split • in two parts at middle of linac • Shieldingisprovided by thermalization • with 80 K return (LHC design)

  22. Cold Mass Estimate Transfer line CM + VB

  23. Cool down time Wholelinacat once (will not happen) Transfer line Cryomodule

  24. Part 3 Cryogenic plant main components Implantation Reliability Preliminary cost analysis Conclusions

  25. Cryogenic system functionalscheme and components

  26. Placement of cryogenic plant and dimensions Heatload center of mass is close to geometrical center Hypothesis : - Building surface linearlyscaleswith power. - Scalingfrom LHC dimensions  In agreement with XFEL (12 kW) dimensions.

  27. Compressor Building : compressors B Bradu. Modelisation, simulation et contrôle des installations cryogeniques du cern. PhD Thesis, 2010.

  28. Liquefier building 4.5 K cold box of the LHC • In MYRRHA (unlike LHC), • 4.5 K and 1.8 K cold box • canbefused in one cold box: • better COP, goal : 720 W/W @ 2K • how to handle large 5.4 kW @ 2K load ? 2.4 kW@ 1.8K cold box of the LHC :

  29. Storage, heliuminventory LHC 20 bar gasstorageat point 1.8 MYRRHA need corresponds to one 250 m3 20 bar bottle

  30. Claudet, “Lhc cryogenics, the approach towards availability,” 2011 • Commeaux, “Reliability of cryogenic facilities: a preliminary approach,” 2002 Reliability • High levels of availability of cryogenic systems (99 %) can be achieved if: • Mean Time Between Maintenance > 8000 hrs • Impurities : dryers to remove water , 80K adsorbers (air), 20 K absorbers (hydrogen), helium guard (2 joints) on 2K circuit • Elements containing moving/vibrating parts : turbines, compressors, etc. • At least two identical machines per stage • Double all oil filters and oil pumps • Periodic maintenance, oil checks, vibration surveillance program • Utilities : common cause of cryogenic system malfunction • Periodic insulation vacuum control (thermal cycling  leaks) • Easily exchangeable cold compressors

  31. Preliminarycostestimate of cryogenic system EUROTRANS report estimate for 8.5 kW @ 4.2 K plant : 24.5 M€ withoutmanpower So : Material 21-25 M€ + Manpower 7-8 M€ = Total 28-33 M€

  32. Conclusions and perspectives • Location of compressor station : too close to linac ? Max achievabledampening of vibrations ? • Linac-refrigeratorconnection: over linac or under the linac ? • Valve box distribution scheme: 1 VB-1 CM or 1VB -2CM ? • Transfer line design, otherpossibilities (SNS, 2 concentrictransfer line ?) • Location of transfer line « T »junction: in cold box or in tunnel ? • How can the refrigeratorbe made more reliable ?  rotating parts • How to integrate the 2K and 4K cold box ? Can the 720 W/W beachieved ? • How to handle the 5.4 kW 2K loadof MYRHHA (twicethat of the LHC) ? • Upgraded cold compressors ? Cold compressors in parallel ? • Detailedcostanalysis THANK YOU FOR YOUR ATTENTION. QUESTIONS ?

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