IDS-NF Mercury System Overview Van Graves IDS-NF 5 th Plenary Meeting April 9, 2010

2Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 Background MERIT demonstrated Hg jet target is feasible for Neutrino Factory Goal now is to further develop the conceptual design for Reference Design Report – ORNL investigating mercury system design to identify operational or functional issues NF Mercury System Concept

3Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 Iron Plug Proton Beam Nozzle Tube SC-1 SC-2 SC-3SC-4 SC-5 Window Mercury Drains Mercury Pool Water-cooled Tungsten Shield Mercury Jet Resistive Magnets Neutrino Factory Study 2 Target Concept ORNL/VG Mar2009 Splash Mitigator General Target Concept w/Downstream Drain

4Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 Cryostat Upstream End Iron Plug Proton Beam (67 mrad) Nozzle Tube SC-1 SC-2 SC-3 Mercury Pool Water-cooled Tungsten Shield Mercury Jet (100 mrad) Resistive Magnets Splash Mitigator

5Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 Front View Includes slope for Hg drainage downstream Mechanical issues between nozzle and beam Splash mitigation scheme incorporated Relatively thin beam stop (Hg depth)

6Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 Cryostat Downstream End Window becomes a liquid barrier Mercury pool serves as additional SC shielding Cryostat becomes trapped by mercury nozzle and drain piping SC-5 Window Overflow Drain Valved Drain Tungsten Shielding

7Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 Front Drain Views Investigated possibility of having the Hg drain from the nozzle end of the cryostat

8Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 Mercury Drain Tungsten Shield Beam Window Front Drain Cross Section View Mercury Chamber extends forward under resistive magnets Allows the mercury exiting the vessel to flow out the front of the cryostat Puts beam window in middle of cryostat

9Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 Flow Loop Review 1 cm dia nozzle, 20 m/s jet requires 1.57 liter/sec mercury flow (94.2 liter/min, 24.9 gpm). MERIT experiment showed that a pump discharge pressure of ~40 bar gauge required to produce the desired jet. – Reference: SNS nominal flow 1440 liter/min (380 gpm), 7 bar gauge pump discharge pressure, ~1400 liters total Hg inventory Basic flow scheme Pump → Nozzle → Jet/Beam Dump → Heat Exchanger → Pump

10Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 Hg Flow Minimize pressure drops through piping by increasing diameter – 2" nozzle supply piping transitioning to 1 cm nozzle Actual NF Hg inventory may reach SNS volumes – ~500 liters in the half- length beam dump shown Overflow Mercury Drain Mercury Pump Gravity Drain Flow Control Valve Storage Tank Heat Exchanger Beam Dump

11Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 Heat Removal From Study 2, the mercury jet/pool receive < 10% of beam energy; 50-60% goes into WC shielding (~2.4MW for 4MW beam) – Currently assumed to be WC spheres cooled by water – Much larger heat exchanger needed to cool shielding Considering that both W and WC must be water-cooled, their effective densities will approach that of Hg. Consequently, IF a Hg target is selected, the infrastructure will be in place to support use of Hg as a solenoid shield. – Would probably be a separate loop due to vastly different flow/pressure requirements, but could share a storage tank Element/CompoundDensity (g/cm^3) Hg13.5 W19.3 WC15.8 Mercury Drain Tungsten Shield Beam Window

12Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 Decay Channel Cryostats Core Vessel Mercury Process Hot Cell Main Cryostat (Target Region) NF Target Building Development Work Using Study 2 concept as a starting point Goal is to produce RDR Target Facility concept with cost estimate

13Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 Potential Future Mercury Work Systems Engineering – Mercury loop refinement and design for remote maintenance – Target/beam dump remote maintenance – Beam window remote replacement – Cryostat/magnet design integrated with mercury jet and beam dump – Facility development Hardware studies – Continuous jet flow loop Nozzle studies, beam dump experiments – Tungsten shielding Thermal / hydraulic studies

14Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 Implications of Using a Mercury Target

15Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 SNS Target Building Layout Target Target Service Bay (Hot Cell) Instrument Ports (9 ea) Proton Beam

16Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 SNS Target Support Utilities Water Cooling Loop Primary & Secondary Confinement Exhaust LLLW Tritium Removal Carbon Filters

17Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 SNS Mercury Related Facilities Mercury-based target systems require extensive support facilities. Mercury Containment – Leaks assumed inside Hg pump room – Leaks in core vessel area routed back into hot cell – Mercury vapors condense and leave activated beads on surfaces unrelated to maintenance operations Hot Cell / Remote Handling – Complex, expensive systems required to maintain mercury equipment and magnet systems Ventilation / Filtration – Hg vapors must be removed from cell exhaust & process off-gas prior to HEPA filtration

18Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 SNS Mercury Related Facilities Cont’d Waste Handling – In US, mercury treatment and disposal governed by the Resource Conservation and Recovery Act (RCRA) (hazardous waste) – Radioactive mercury imposes additional requirements In the US, this type of waste is called “mixed waste”. Disposal options are VERY limited. Water Cooling System – Process mercury cooled with secondary water system – Hands-on maintenance after beam-off Mercury Target Safety Considerations – Accident & hazard analyses required to ensure protection of workers / public / environment Operational Considerations – Maintenance of Hg systems complex, long downtimes expected – Maintenance of remote tooling is significant operational cost

19Managed by UT-Battelle for the U.S. Department of Energy Mercury System Overview IDS-NF 6 Apr 2010 Summary Work continues towards development of mercury-jet- based target system for Neutrino Factory Several engineering challenges remain in the design of a mercury nozzle / beam dump SNS experience highlights the realities and challenges of using a mercury target