P. Gobby, A. Nobile, J. Hoffer, A. Schwendt
and W. Steckle
Concepts for Fabrication of Inertial Fusion Energy Targets
Goal of this work is to evaluate the feasibility of fabricating targets for an IFE plant at an acceptable cost
Develop concepts for target fabrication plant: Iterate with target designers, agree on acceptable target materials and
tradeoffs Evaluate processes for fabrication of targets in large quantities at low cost Evaluate the tritium inventory of a target filling facility
Begin demonstrating synthesis of key target materials. Evaluate response of the direct drive cryogenic target to the target chamber during
rapid injection Evaluate capital and operating cost of a target fabrication facility. Define issues for future R&D needed to achieve cost goals.
Target fabrication feasibility and cost is being evaluated for HIF and Direct Drive approaches
Baseline target for HIF is close-coupled target Callahan-Miller, et al.
Baseline target for Direct Drive is NRL target design
The HIF target has many parts, but only a few different types of materials
DT (solid and gas) CH (capsule) Fe foam Al foam Metal-doped CH foam Metal hohlraum D2
CH foams + metals
hohlraums
Fill capsules + layer
Metal foams Pre-assemble
Fabricate capsules
Final assembly & Inject
ORhohlraums
Metal foams
CH foams + metals
Fabricate capsules
Assemble Fill capsules + layer Inject
There are two major approaches in the target fabrication and filling process for HIF (indirect drive) targets
Fill capsules + layerFabricate capsules Inject
Direct drive IFE target fabrication is simple
HIF IFE target filling sequence
“Cold Assembly”
DTDiffusion
Fill
Coolto Cryo Temps
EvacuateDT DT Ice
Layer
AssembleHohlraum
Hohlraum CryogenicAssembly
DT IceLayer
InjectManufacture
Materials
TSH
CAH
“Warm Assembly”
DTDiffusion
Fill
AssembleHohlraum
Coolto Cryo Temps
EvacuateDT
DT IceLayer
TSH
We are using a JIT approach to evaluate minimum tritium inventory required for the fill process
“Cold Assembly”
DTDiffusion
Fill
Coolto Cryo Temps
EvacuateDT
DT IceLayer
AssembleHohlraum
InjectManufacture
Materials
DT inventory during filling
DT pressures during filling
DTDiffusion
Fill
Pre
ssur
e
fill pressure
Time
PressureP(t)P ext(
t)
gfill_outsideMW V Vcapsule−( )?
R Tfill? 0
Nfill
nPext n( )
d?:=
gfill_insideMW Vinner?
R Tfill? 0
Nfill
nP n( )
d?:=
Nfill = (shot rate) x (fill time)
Pext, V
Vcapsule
P, Vinner
fill time
Po{
gfill_TOTAL gfill_outside gfill_inside+:=
HIF tritium inventories have been evaluated for fill in hohlraum and fill before assembly
The above analysis has been performed to evaluate “minimum” tritium inventory - this allows comparison of inventories for different IFE approaches without assuming any engineering approach
“Actual” tritium inventories based on real engineering scenarios will be evaluated in the future
HIF-fill inhohlraum
HIF-fill beforeassembly
Direct Drive
Buckle Pressure 533 atm 533 atm .062 atm
Fill Time 4 hours 4 hours 5 days
Tritium Inventory(beta-layering only) 29.4 kg 1.5 kg 8.9 kg
Tritium Inventory(beta-layering + IR) 28.9 kg 1.0 kg 8.4 kg
Theoretical Minimum tritium inventory (Actual inventories will be higher)
Cool time - 2 hr Evac time - 1 hr layer time - 8 hr IR layer time - 2 hr Fill overpressures
are 75% of buckle pressure
Target fabrication process modeling to produce targets at capacities necessary for an IFE plant is underway
1
WATER-1
B1
S1
B3
OIL-1 S4
B4
B5
S2
S3
S5
Stream HeatersInput Streams100 Liter PAMS Mandrel
PolymerizationReactor
Water Decant Stream
B8
S 8
S 9
PAMS Mandrel/Water Separator
Shell Water WashB6
Ethanol Extraction
S 6
S 7
B9
B10
AIR-1
S 11
S 12
Fluidizd BedPI or GDP
Coat Capsule
S 13
B11
Fluidized BedDrier
S 14
Capsule Manufacture
S 10
S 15
S 16
Uses existing PAMS/GDP technology that is currently used to produce ICF capsules.
Existing bench scale processes are being scaled up using chemical plant design software (Aspen Plus)
We are attempting to demonstrate fabrication of metal-doped foams
• Foams with composition of (CH)0.97M0.03 are the current focus. Foam densities of 11 and 32 mg/cc are needed.
• Metals must have the desired x-ray emission characteristics, acceptable ES&H properties, as well as chemistry and separation characteristics that are compatible with the reactor Flibe and balance of plant.
• We have demonstrated synthesis of polystyrene foam with a densities of 10 mg/cc and 32 mg/cc.
• The lower density foam is very fragile.
• We are preparing to conduct experiments to demonstrate doping of foams with various metals (Au, W, Ta, Hf, Sc, Re, and Bi) using a simple wet impregnation technique.
• We have developed a list of candidate organometallic compounds to be used for doping studies.
10 mg/cc
Critical issues
• Cold assembly of targets will have to be developed to keep tritium inventories low.
• Innovative approaches to DT filling will have a large leverage in reducing tritium inventories.
– Liquid DT injection
– Be foam structural enhancement of capsules
– Improved permeability and strength of capsule materials
• Scale-up of materials fabrication processes is an important issue.