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

IDS-NF Mercury System Overview

Van Graves

IDS-NF 5th Plenary MeetingApril 9, 2010

2 Managed by UT-Battellefor 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


IronPlug

ProtonBeam

NozzleTube

SC-1

SC-2 SC-3 SC-4SC-5

Window

MercuryDrains

MercuryPool

Water-cooledTungsten ShieldMercury

Jet

ResistiveMagnets

Neutrino Factory Study 2 Target Concept

ORNL/VGMar2009

SplashMitigator

General Target Concept w/Downstream Drain


Cryostat Upstream End

IronPlug

Proton Beam(67 mrad)

NozzleTube

SC-1SC-2 SC-3

MercuryPool

Water-cooledTungsten Shield

Mercury Jet(100 mrad)

ResistiveMagnets

SplashMitigator


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

• Window becomes a liquid barrier• Mercury pool serves

as additional SC shielding• Cryostat becomes

trapped by mercury nozzle and drain piping

SC-5

Window

OverflowDrain

ValvedDrain

TungstenShielding


Front Drain Views

• Investigated possibility of having the Hg drain from the nozzle end of the cryostat


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


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 schemePump → Nozzle → Jet/Beam Dump → Heat Exchanger → Pump


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


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/Compound Density (g/cm^3)

Hg 13.5

W 19.3

WC 15.8Mercury Drain Tungsten Shield

Beam Window


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


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

• http://www.hep.princeton.edu/~mcdonald/mumu/target/graves/graves_121708.pdf

http://www.hep.princeton.edu/~mcdonald/mumu/target/graves/graves_121708.pdf


SNS Target Building Layout

Target

Target Service Bay (Hot Cell)Instrument Ports (9 ea)

Instrument Ports (9 ea)

Proton Beam


SNS Target Support Utilities

Water Cooling Loop

Primary & SecondaryConfinement Exhaust

LLLW

TritiumRemoval

Carbon Filters


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

• 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

• 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

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

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