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Qweak Target Meeting Greg Smith, Dave Meekins , Mike Seely , Silviu Covrig January, 2008

Qweak Target Meeting Greg Smith, Dave Meekins , Mike Seely , Silviu Covrig January, 2008. Design Questions Signals/Feedthrus Relief Stack Job Jars Schedule Safety/Relief Calculations. Top Plate Design Questions. Coolant standoffs Length “cut to fit” by tgt grp

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Qweak Target Meeting Greg Smith, Dave Meekins , Mike Seely , Silviu Covrig January, 2008

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  1. Qweak Target MeetingGreg Smith, Dave Meekins, Mike Seely, SilviuCovrigJanuary, 2008 • Design Questions • Signals/Feedthrus • Relief Stack • Job Jars • Schedule • Safety/Relief Calculations

  2. Top Plate Design Questions • Coolant standoffs • Length “cut to fit” by tgt grp • Interferences? Accessibility? Relative height? • Several sizes in use at Jlab, Bert needs your guidance here • Lifter EC position fixed • Electrical feedthrus • Bert needs input asap (part goes out this week) • How many of what type? • HPH feedthru config (2 or 2*4?) • Spares

  3. Top Plate Layout

  4. Coolant Standoffs

  5. TargetSignals

  6. Electrical Feedthroughs

  7. Relief Plumbing Questions • Fill line and separate return line • Opposite sides of pump • Mike suggests very small fill line, has to go on suction side of pump • Coaxial (sort of) to main 2 7/8” id vent • Ok? Thermal crosstalk a problem? • ½” fill line. OK? Bigger? With a gusset. • Pump geometry fixed to opposite leg as relief line. • Means return line attaches to upper corner opposite pump, on output side of pump • So can’t ever use this to fill the target! • Pump differential pressure relative to ½” fill line • Fill & return mainly tube, with short hose • Heater tape? • Separate tap for vapor pressure bulb? Coaxial too?

  8. 15K stand-off Relief Design to ballast tank 300K sleeve G10 spacer 4K stand-off 2 7/8” id cold relief 6” od relief bellows (3.5” id) short flex hose to loop to accommodate horizontal motion (not shown)

  9. Coaxial Fill Line Fill: ½” Return: 2 7/8” id

  10. Up & Down Return: 2 7/8” id Fill: ½”

  11. Broken Symmetry • Given: • Pump must be on opposite side as relief stack. • Fill line must be on inlet side of pump. • Heater will be on the leg opposite to the HX. • Question: • Which side of pump should HX be on? Suction side, as shown here? Or the other side?

  12. Coarse Schedule • Safety Review this spring • Test pump in LN2 late spring • Must decide if we need to go commercial by August • Assemble tgt this summer • Test tgt this fall in test lab with GHe • Neon test spring 2009 • Install in Hall C fall 2009 • LH2 test winter 2009-2010 • Run for Qweak spring 2010-2012

  13. Bert’s Design Job Jar • Transition between 2 scattering chambers • Needs pump, HX geometry (fixes ht) • SC window • Needed for Safety review? • SC ports • Where? How many? • Motion mech’s • Relief stack • Cryostacks • New relief/vent plumbing • Top plate • Needs feedthru info • 8” SS pipe • Bracket that fixes the loop to the 8” pipe • Loop basics • Qweak Support/Storage tripod • Support plate • HKS stand to SC • Gas Panel schematic

  14. Target Group Design Job Jar(with some help from GRS, SDC) • Cell • Cell manifolds • Cell positioner • Exit window • >7” diam, .005” nipple • Entrance window • Pump • HX • Dummy target/ladder design? • Bert/Dan? • Gas Panel • Hall C techs? • GRS/SDC • Loop details • Survey tools • Help on safety document • Dump G0 D2

  15. The Fast Track • Motion Mechanisms built by March • Relief stack & top plate built by March • Tripod by March • Pump prototype • Build early spring, test by late spring • Need 1 year if we have to go to BN • HX could be ready in 3 weeks... • Cell mechanical design by spring • Fabricate late spring/early summer • Heater by summer (MSU) • Gas panel by summer • SC ready by fall • Transition, ports

  16. The Slow Track • Plate for HKS stand/Sample SC transition • SC window (a big job) • Cell positioner • Need a wag though • New Relief & Vent plumbing • Final exit & entrance windows • Need something though (could be thick) • Ballast tanks • New HX from cryo • Dummies • New HX for CHL return from cryo group

  17. Dirty gas to CHL CHL 4.5K 3 atm 300K 4 atm supply House Helium Line (300K Supply) 20K, 3 atm return Hall C 15K, 12 atm supply WR Line 20K Return Line 4K, 3 atm supply New HX 5K, 1 atm return HMS *warm* 15K Supply 12 atm Line 4K 3 atm Supply Line Warm return T ESR Short New Ins. Line Hall C Moller H2 Ballast Tank 20K Return Line H2 vent QW Tgt LP HX: 20 K 2.5 atm Return HP HX: 20 K 1 atm return Qweak Gas Panel 20K, 50 psia LH2 Loop Oct., 2007, GRS

  18. Relief Calculation Strategy • Follow “Hydrogen Safety Assessment Document” written by Mike Seely for the Jlab LH2/LD2 targets in 2004 • Reproduce those calculations: • Get Mike Seely to agree with results • Compare to actual performance • Use the resulting tested and certified template to design & calculate Qweak relief in 3 scenarios: • Design for a sudden LOV incident • Design for a cell rupture • Worst case accident: inventory dumps into Hall C (1/2 done)

  19. Basic Relief Outside Vent Relief Line BallastTank Outside World Inside Hall C 1) LOV, No Ruptures 3) Cell & Window Rupture into Hall C 2) Cell Rupture Scattering Chamber

  20. Sudden LOV • Assume target cell remains intact • LH2 boils rapidly and relieves to ballast tank • No gas gets into vent header (relief valves remain closed) • Can occur if: • A scattering chamber window breaks • A pump fails • A valve to atmosphere inadvertently opened • Will be deliberately tested (with Neon) • Want to calculate: Maximum pressure rise • Assumptions: • External plumbing is 300K (worst case) • Internal plumbing stays at 80K (worst case is 300K) • Superinsulation (worst case is no superinsulation) X X

  21. Ballast Inventories

  22. More Storage? Existing: 2 2500 gal tanks 1 1000 gal tank Drop PopPstorage drops • Assumes: • 45 psia Poperating • 52 liters LH2 • More storage doesn’t really help that much: • Doubling Vstorage only reduces Pstorage ~20% • because Poperating is so high • Puts more gas into hall in event of an accident

  23. Sudden warmup, Hall C tgt, Nov. 13, 2007: Observed ΔP=1.6 psi Calculated ΔP=2.6 psi Conservative assumptions Sudden LOV 300K external relief lines 80K internal relief lines Observed Δt~5 min Calculated Δt=2 min Baselining Pstorage ΔP Pressure Temperature Pretty reasonable agreement!

  24. Qweak Heat xfer Coefficients

  25. Heat Load from Heat Flux and Area Not that different from the Hall C standard pivot target!

  26. 15K stand-off Relief Design to ballast tank 300K sleeve G10 spacer 4K stand-off 2 7/8” id cold relief 6” od relief bellows (3.5” id) short flex hose to loop to accommodate horizontal motion (not shown)

  27. Qweak LOV ΔP With the plumbing that exists in the Hall right now. Using existing ballast tanks. 45 psia operating P. Superinsulation on loop except at windows. 52 liters LH2. Completely reasonable! ~Same as for existing Hall C tgt

  28. Relief Path Question: relief lines have a goofy bottleneck where they connect to the ballast tank: looks like 2” to 1” to 2”.

  29. Sudden LOV Results Note: 75 psia storage pressure, 100 psia reliefs on ballast tanks:  ΔPmax = 25 psi Conclusion: With minor mods to existing Hall C plumbing, we can withstand a sudden LOV even if all SI is blown away!

  30. Relief Plumbing • Tie into existing 2” relief lines to ballast tank here, with 40’ of new 2” line to the Qweak target (replacing existing 1” lines).

  31. Sudden LOV Summary • Ballast: 2 G0 + 1 Hall C tank looks OK • Adding a 3rd “G0 tank” may be desirable • To handle most realistic case, do not need to do anything • To handle worst case, need to: • Replace 1st 20’ of 1” hose with 2” or 3” hose • Replace next 45’ of 1” tube with 2” tube • Put both 150’ 2” lines back to tanks in ||

  32. Cell Rupture • Assume target cell ruptures • LH2 inventory dumps into scattering chamber • Scattering chamber windows remain intact • It boils rapidly and expands • Must handle entire gas inventory until ballast tank reaches 1 atm • Reality: not hard to keep ballast gas outside hall • Can occur if: • Relief line back to ballast tank becomes blocked • Structural failure of cell • Will not be directly tested, • but all components must be tested to 1.5* Pmax expected in a sudden LOV incident • Want to calculate: Scattering Chamber ΔP • Note: no downstream beamline gate valve

  33. Need some extra (beam pipe) volume to slow it down. (we have it: no gate valve!) Qweak cell rupture

  34. Heat xfer rate Function of the scattering chamber geometry (and initial conditions) Still have to include heat transferred to gas from beam pipe volume. Makes things worse.

  35. Result Existing!

  36. Vent Path 2” vent line • Scatt. Chmbr vents thru burst disk & relief valve in || • Can use same plumbing for Qweak

  37. Existing 2” Vent Line Vent Path Dome penetration Vent Stack Eight 4” penetrations to outside

  38. Cell Rupture Results • Must add some beam pipe volume • Allows liquid to boil away without increasing pressure inside scattering chamber • No space for a downstream gate valve anyway • Calculation assumes 52 liters LH2 • Existing 2” vent plumbing is adequate! • More penetrations are available • SC ΔP(Qweak) < ΔP(Standard Hall C tgt) • Caveat: have not treated beam pipe volume yet... • Additional dump volumes possible in principle

  39. Worst Case Accident • Simultaneous failure of Scattering Chamber windows AND Cell rupture • Very unlikely, but • Projectile from outside could penetrate both in principle • Cell rupture could potentially puncture SC windows • Have to assume H2 inventory gets into Hall C • until ballast tank reaches 1 atm • Even though this can be prevented with good design

  40. More on Gas Inventories

  41. Options in worst case scenario • Let it go (current solution): • no roof on tgt shield cave • vacuum interlock top plate electronics • lifter, heater, JTs, etc. • rely on Hall volume, dome vent • Or, in addition (cuz of P wave problem): • Provide large vent hood over tgt top plate • “dryer plumbing” to 2’ φ Hall penetration • possibly also kick (explosion proof) vent fan on with vacuum interlock

  42. Finished

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