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UCN Beamline Shielding, Target & Remote-Handling UCN CDR (Sept/2010) L.Lee
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UCN Shielding Requirements A.Trudel calculations (TRIUMF Safety Group) 40 A, 500 MeV protons stopping in W target Assumes 0.5 m empty space around target (no moderator) Plot shows the shielding needed to reduce dose to 3 Sv/hr outside General Layout of Shielding Structure Inner layer of Steel Outer layer of Concrete
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Shielding Costs Latest UCN Layout Vendor Quotes: Concrete$1251 k Steel (radioactive)$ 360 k (66%) Steel (new)$ 480 k (33%) Staging/Installation$ 20 k Total$2111 k Latest UCN Layout: Concrete$ 834 k Steel (radioactive)$ 240 k (66%) Steel (new)$ 320 k (33%) Staging/Installation$ 20 k Total$1414 k Original Cost Estimate (CFI prop): Concrete$ 900 k Steel (radioactive)$ 200 k (66%) Steel (new)$ 700 k (33%) Staging/Installation$ 20 k Total$1820 k Above estimates based on bulk volume estimates+20% contingency More detailed layout TRIUMF Design Office (A.Prorok)
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Detailed Layout of UCN Shielding (1 st Iteration) Extent of existing Shielding Wall UCN Concrete Shielding UCN Steel Shielding
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UCN Shielding – Layer 1 Concrete shielding blocks – Yellow Steel shielding blocks – Black/Silver
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UCN Shielding – Layer 3
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UCN Shielding – Layer 5
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UCN Shielding – Layer 7
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UCN Shielding – Layer 9
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UCN Shielding Structure 4’ x 6’ x 18’ Concrete shielding blocks (on-hand, outside “Electronics” Trailer) Reuse existing concrete blocks from M11/M13 1836 ft 3 ~50 m 3
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Shielding Costs from 1 st Iteration Layout Possible Cost Savings: “Skyshine” dose limits are higher remove uppermost 2 layers of shielding (?) savings of ~ 22% $225 k Reuse existing steel from magnets possible savings $ 75 k Total savings $300 k 1 st Iteration UCN Layout: Concrete$ 445 k Steel (radioactive)$ 485 k Steel (new)$ 240 k Staging/Installation$ 20 k Total$1190 k If above savings can be implemented, total cost for shielding $890 k 2 nd Iteration Layout Possible further improvements in “blocking” efficiency
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Initial startup at 2 A (500 nA time-averaged) Target cooling and residual activity not a major issue RCNP @ 1 A radiative cooling found to be adequate residual activity very low At higher currents 40 A (10 A time-averaged) Require Target Cooling Water-cooling vs Helium-cooling Model target after elements from existing designs at BNL, KEK, TRIUMF Budget: $30k Residual Activity & Remote-Handling Retract target into a shielded cask TRIUMF Remote-Handling specialists consulted do-able at $100k Target failure Transfer to Horizontal transport flask (e.g. 2C-STF flask) and crane to existing Hot Cell facility Prior to installation at TRIUMF (recent initiative with RCNP) Spallation Target & RH system use at RCNP RCNP: 2 A to 10 A (instantaneous) Ideal opportunity to test system and resolve Cooling/RH issues Spallation Target & Remote-Handling System
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Target Design BNL target Pt target (segmented) coupled to Copper base Water-cooled base Heat load ~ 2kW (time-avg) TRIUMF people involved in design of this target UCN target Tungsten alloy (HeavyMet) target; d~5 cm, L~11-14 cm Coupled to water-cooled base (Cu?) Heat load ~ 5kW (time-avg) Water flow rate ~10 L/min to remove instantaneous heat load Model target after BNL target
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Beam 300K D 2 O 20K D 2 O Target Cooling Block Coolant Lines Rails/Bearings Bellows Rack & Pinion System Driveshaft (detachable) Pb-Shielded Cask Pb-Shielded Shutters Flexible Shaft (remote-control cables) He 80 cm Remote-Handling System (Upstream Withdrawal) Pb-Shielded Cask and Target Mounting System
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Water-Cooling Setup for 1AT1/T2 Target Ladder Bellows & Coaxial water lines on Target Ladder Custom seals TRIUMF M/Shop
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Target in Retracted Position Retract Target into Cask Access UCN cryostat OR Prep for Target Removal
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Target Removal/Disposal External Transport Flask (e.g. 2C-STF flask) Relocate Target + Cask to external (horizontal) transport Flask Crane to Meson Hall Hot-Cell facility
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Costs & Human Resources Summary More details in main Resources & Timeline Section Possible reduction in Human Resources requirements: RCNP (Tgt), Acsion (Tgt, Shielding)
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Shielding: Final designmid-2012 Procure shielding mid-2012 mid-2014 Install Base layer mid-2013 Dec/2013 Install remaining layersmid-2014 mid-2015 Target & RH system: Receive Target @ TRIUMF: Mar/2014 Install Target @ TRIUMF: May/2014 Schedule: Shielding and Target/RH Overview of Main Milestones (details in Resources & Timeline Section)
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The End
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Shielding Costs ORIGINAL (“With PIF”) UCN LayoutNEW (“No PIF”) UCN Layout Shielding Budgets Original cost estimate (total) $1820 k (from CFI proposal) Vendor Quotes: Concrete$1251 k Steel (radioactive)$ 360 k (66%) Steel (new)$ 480 k (33%) Staging/Installation$ 20 k Total$2111 k Latest UCN Layout: Concrete$ 834 k Steel (radioactive)$ 240 k (66%) Steel (new)$ 320 k (33%) Staging/Installation$ 20 k Total$1414 k
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UCN Shielding – Layer 2 (Base Layers)
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Water-cooling vs Helium-cooling Water CoolingHelium Cooling Good cooling efficiencyLow cooling efficiency high flow velocities req. “Conventional” technologyGreater Technical & Regulatory (ASME) complexity Activation of waterLow Activation Leaks Contamination RisksLow Contamination Risks Boiling of Coolant Two Water-cooled targets (1AT1 & 1AT2) in operation “near-by” Water-cooling infrastructure already available
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Spallation Target Calculations from Safety (A.Trudel) indicates target activity level after 10 years of irradiation will still be a factor of ~5 below the A 2 transport limit A stopping target of tungsten bombarded with 100 uA of 500 MeV protons. Blue arrows correspond to 1, 5 & 10 years of irradiation. Shown below the arrow is the total activity as a fraction of the A 2 transport limit. The inventory of activity in the target at ten years is at approximately one fifth of the A 2 transport limit for Type A packages.
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