Liquid Lithium Argonne
-
Upload
hahanonsense81 -
Category
Documents
-
view
224 -
download
0
Transcript of Liquid Lithium Argonne
-
8/10/2019 Liquid Lithium Argonne
1/19
Engineering and safety issues of lithiumtargets and film strippers
3rd High-Power Targetry Workshop
September 10 - 14, 2007
Bad Zurzach, Switzerland
Claude B. Reed, Jerry A. Nolen, and Yoicihi Momozaki
-
8/10/2019 Liquid Lithium Argonne
2/19
2
Presentation Overview
Liquid Metal Systems for High Power Accelerators
Targets
Thin Film Strippers Beam Dumps
Technical Issues
Engineering
Thermalhydraulics Liquid metal pumps
Alkali Metal Safety Issues
Control of impurities
Alkali metal handling
Fire protection
Waste treatment & disposal
-
8/10/2019 Liquid Lithium Argonne
3/19
3
AEBL Liquid Metal Systems
AEBL Targets
for heavy-ion beams on low-
Z targets
for light-ion beams on high-(Z) targets
AEBL Thin Film Strippers
within the driver linac increases ion beam charge
state
AEBL Liquid Metal Beam Dumps
end of the production area low melting point
low vapor pressure
Liquid lithium stripper
Liquid lithium targetLiquid tin beam dump
Color code:
Black = existing facili ty
Blue+ green = AEBLbaseline
Red = Low-cost upg rade
-
8/10/2019 Liquid Lithium Argonne
4/194
RIA Windowless Li Target
heavy-ion beams on
a low-Z (Li) target
Beam energy: 400 MeV/u
Beam power: 400 kW
Beam diameter: 1 mm
Target thickness: 1.5 g/cm2
-
8/10/2019 Liquid Lithium Argonne
5/19
5
Windowless Target- Experimental Layout, Setup, and Instrumentation (contd)
Beamline
Loop in heat shieldVacuum system
Gate valve
Heater wiring
Windowless Liquid Li Target Loop
Splash
Shield
-
8/10/2019 Liquid Lithium Argonne
6/19
-
8/10/2019 Liquid Lithium Argonne
7/19
7
The Choice of Liquid Lithium
Low Z (=3)---good from nuclear considerations
Large working temp range T ~ 1160 C
High boiling point (1342oC)
Low melting point (181oC)
Low vapor pressure (10-7 Pa at 200oC)---only Ga and Sn lower Lowest pumping power required because:
Lowest density (511 kg/m3)---easiest liquid metal to pump
High heat capacity ( 4.4x 103 J/kg-K)---highest of liquid metals
Low viscosity (5.4 x 10-4 Pa-s)
Low Prandtl No. ~0.05 excellent heat transfer
Applications
Heat Transfer fluid to cool solid targets with light-ion beams
Functions as combined coolant and target for high-power heavy-ion
beams
-
8/10/2019 Liquid Lithium Argonne
8/19
8
Liquid Metal Engineering Issues
Materials of construction
Mechanical joint designs
Sealing materials
Secondary containment
Heating system design
Wetting of EM pumps & flowmeters
-
8/10/2019 Liquid Lithium Argonne
9/19
9
Material Compatibil ity with Liquid Lithium
Liquid lithium dissolves most materials including:
Metals Cu, Ag, Au, Ni
Can not use Cu gaskets Lost 41% of gasket mass in less than 4 hours
of operation causing major vacuum leak
Ceramics, glasses
Concrete
Organics
Liquid lithium systems can be fabricated from
Stainless steel
Fe, Ta, Mo, Nb, Be
-
8/10/2019 Liquid Lithium Argonne
10/19
10
Mechanical Joint Designs
Metal-to-metal seals are necessary for
liquid alkali metals
1. Grayloc flanges w/17-4 PH SS
seal rings2. Conflat flanges w/soft iron
gaskets
3. Hollow SS o-rings w/high polish
surface finish
4. Cajon flanges w/SS gaskets
Suitable for both pressure & high
vacuum
-
8/10/2019 Liquid Lithium Argonne
11/19
11
Containment Objectives
Prevent water from contacting any lithium in the system.
Prevent air from contacting hot, molten lithium.
Fabricate containment from proper materials.
Secondary containment is essential.
Ideal:
sealed containment, enclosing primary vessel, with inert gas backfill,
maintained at a temperature below the melting point of lithium.
Minimum:
containment of any liquid lithium spills and splashes, with a negative
pressure air flow through a aerosol removal system.
-
8/10/2019 Liquid Lithium Argonne
12/19
12
Secondary Containment
Necessary to minimize consequences of
alkali metal leak
ANL/MSU Li/Be target
2-part containment
Beamline vacuum system
SS containment cover
-
8/10/2019 Liquid Lithium Argonne
13/19
13
Target & Stripper Heater Systems
Multiple-zone control system to
minimize hot spots
Ceramic band heaters provide
easy installation
-
8/10/2019 Liquid Lithium Argonne
14/19
14
ANL/MSU DC EM pump foradjustable thickness target
DC EM pump for AEBL
Windowless target
EM Pumps
-
8/10/2019 Liquid Lithium Argonne
15/19
15
Lithium Reactivity
Lithium is the least reactive of all alkali metals.
Nonetheless, liquid lithium is still very reactive.
The most violent reactions of liquid lithium occur with:
Water
Water vapor
Organics
Fluorocarbons
Lithium reacts slowly with oxygen and nitrogen.
H2 is evolved from water and many organic reactions with Li.
H2 is explosive in concentrations between 4% and 74.2% in air.
Li3N violently decomposes on contact with moisture.
-
8/10/2019 Liquid Lithium Argonne
16/19
16
Lithium Fires
Potential for fire exists only when lithium is molten at a temperature greater
than 400oC in dry air.
Fire has been reported to occur at temperatures as low as 200oC in very
moist air.
Potential for fire suggests that a fire/safety watch be present when opening
a lithium filled system for experimental modification, maintenance or any
task requiring Li exposure to air or water.
Graphite and powdered carbon (Lith-X) are the most popular effective
extinguishing agents.
-
8/10/2019 Liquid Lithium Argonne
17/19
17
Additional Operational Safety Considerations
Properly trained personnel.
Continuously monitor experimental systems when Li is flowing.
Heater coverage should approach 100% to eliminate cold spots.
Slowly increase pump current when establishing flow.
Place TCs at suspected cold spots in addition to heater controls/monitors.
Heat system reservoirs prior to internal passages to eliminate expansion
problems (~1.5% volume expansion upon melting).
Add lithium to cold system if possible.
Solid Li tends to stick to hot surfaces.
-
8/10/2019 Liquid Lithium Argonne
18/19
18
Decontamination and Cleaning
Use gloves and eye protection.
Clean components in a hood or ventilated glove box like enclosure.
H2O is easiest and simplest cleaning agent.
Limit quantity of reactive Li to about 10 g per event.
Use approximately 500 ml of H2O per gram of Li to be reacted.
Completely disassemble components Water will not penetrate cracks and
crevices to react Li.
Water will be very basic. Treat appropriately before disposal.
-
8/10/2019 Liquid Lithium Argonne
19/19
19
Conclusions
Liquid Metal Systems for High Power Accelerators
Targets---Look very promising, 20kW beam on target in 9/03
LiLiT (SARAF Li Target)
Thin Film Strippers---development underway Beam Dumps---currently evaluating feasibility
Technical Issues
Engineering---well understood
Stripper film thickness---currently measuring
Liquid metal pumps ---10-20 atm. pump required for Li stripper
Thermalhydraulics---bubble formation & boiling---Momozaki talk
Alkali Metal Safety Issues
Control of impurities---standard cold & hot trap technology
Alkali metal handling---well understood
Fire protection---well understood
Waste treatment & disposal---well understood