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

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ids nf mercury system overview

IDS-NF Mercury System Overview

Van Graves

IDS-NF 5th Plenary Meeting

April 9, 2010

background
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

general target concept w downstream drain
General Target Concept w/Downstream Drain

Neutrino Factory Study 2 Target Concept

SC-5

SC-2

SC-3

SC-4

Window

SC-1

Nozzle

Tube

Mercury

Drains

Mercury

Pool

Proton

Beam

Water-cooled

Tungsten Shield

Mercury

Jet

Iron

Plug

Splash

Mitigator

Resistive

Magnets

ORNL/VG

Mar2009

cryostat upstream end

SC-3

SC-2

SC-1

Nozzle

Tube

Proton Beam

(67 mrad)

Mercury

Pool

Iron

Plug

Mercury Jet

(100 mrad)

Water-cooled

Tungsten Shield

Splash

Mitigator

Resistive

Magnets

Cryostat Upstream End
front view
Front View
  • Includes slope for Hg drainage downstream
  • Mechanical issues between nozzle and beam
  • Splash mitigation scheme incorporated
  • Relatively thin beam stop (Hg depth)
cryostat downstream end

SC-5

Window

Overflow

Drain

Valved

Drain

Tungsten

Shielding

Cryostat Downstream End
  • Window becomes a liquid barrier
  • Mercury pool serves as additional SC shielding
  • Cryostat becomes trapped by mercury nozzle and drain piping
front drain views
Front Drain Views
  • Investigated possibility of having the Hg drain from the nozzle end of the cryostat
front drain cross section view
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

Beam Window

Tungsten Shield

Mercury Drain

flow loop review
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

hg flow

Overflow Mercury Drain

Mercury Pump

Beam Dump

Gravity Drain Flow Control Valve

Heat Exchanger

Storage Tank

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
heat removal
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

Beam Window

Tungsten Shield

Mercury Drain

nf target building development work

Decay Channel Cryostats

Main Cryostat (Target Region)

Core Vessel

Mercury Process Hot Cell

NF Target Building Development Work
  • Using Study 2 concept as a starting point
  • Goal is to produce RDR Target Facility concept with cost estimate
potential future mercury work
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
implications of using a mercury target
Implications of Using a Mercury Target
  • http://www.hep.princeton.edu/~mcdonald/mumu/target/graves/graves_121708.pdf
sns target building layout
SNS Target Building Layout

Instrument Ports (9 ea)

Proton Beam

Instrument Ports (9 ea)

Target Service Bay (Hot Cell)

Target

sns target support utilities
SNS Target Support Utilities

Carbon Filters

Tritium

Removal

LLLW

Water Cooling Loop

Primary & Secondary

Confinement Exhaust

sns mercury related facilities
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
sns mercury related facilities cont d
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
summary
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