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Government Labs

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Title: Government Labs


1
IFE First Wall Survival Development and Testing
of an Armored Ferritic L L Snead, G. R.
Romanoski, C. A. Blue, and J. Blanchard
  • Government Labs
  • NRL
  • LLNL
  • SNL
  • LANL
  • ORNL
  • PPPL
  • Universities
  • UCSD
  • Wisconsin
  • Georgia Tech
  • UCLA
  • U Rochester
  • PPPL
  • UC Santa Barbara
  • UNC
  • DELFT
  • Industry
  • General Atomics

Presented at the 16th TOFE, Madison Wisconsin
September 16, 2004
2
HAPL IFE First Wall Materials
Carbon and refractory metals (tungsten)
considered - Reasonably high thermal
conductivity at high temperature (100-200
W/m-K) - Sublimation temperature of carbon
3370C - Melting point of tungsten 3410C
In addition, possibility of an engineered
surface to provide better accommodation of high
energy deposition is considered - tungsten
coated ferritic or SiC - carbon brush
structures - tungsten foam
3
Unique Threats to IFE First Wall
Intense cyclic heating - stresses and
sublimation due to pulse heating (Renk talk this
session) - cyclic stress induced debonding -
long-tem thermal stability Surface removal
due to high energy ions.
4
Temporal Distribution of Heat Flux
Instantaneous Heat Flux 10 MW/m2 (MFE) 104
MW/m2 (IFE)
5
Effect of Heat Flux on W-Armor Coated SiC
Raffray data
0 1 2 3 4 5 6
7 8 9 10
Time (microseconds)
6
Fabrication Process W/F82H
  • Two processes for bonding low activation
    ferritic to tungsten are considered
  • Diffusion Bonding and Plasma Spray
  • I. Diffusion-bonded tungsten foil (.1 mm
    thickness)
  • - Allows the best possible mechanical
    properties
  • and surface integrity
  • - Tungsten will remain in the
    un-recrystallized state
  • - No porosity
  • --gt Plates of W/Fe (ORNL) have
  • been produced and are being tested.
  • II. Plasma-sprayed tungsten transition coatings
  • - Allows for a graded transition
    structure by blending
  • tungsten and steel powders in an
    intermediate layer
  • to accommodate CTE mismatch.
  • - Resulting microstructure is
    recrystallized but small grain size
  • - May be spayed in vacuum or under a
    cover gas (wall repair)
  • - Variable porosity

7
Testing of Armored Ferritic W/F82H
The primary concern for armored materials is
the survival of the interface --gt CTE
mismatch produced during processing --gt
Stressed induced during pulsed heating --gt
Stability of a ductile interfacial region on
long-term annealing
Specimen Expansion (ppm)
Temperature (C)
8
High Density Infrared (HDI) Plasma Arc Lamp
Technology
  • Unique high density infrared plasma arc lamp
  • Most powerful radiant arc lamp in the world
  • Broad area processing with high radiant energies
  • Conservative heating rates
  • 2,000?C/s to 20,000?C/s
  • Allows controlled diffusion
  • on nanometer scale
  • Able to melt Rhenium
  • Melting point of 3180?C

9
Thermal Fatigue Testing
W coated specimen
Cooling table
Rep rate 10Hz Max. flux 20.9MW/m2 (20ms) Min.
flux 0.5MW/m2(80ms) Duration 1000
cycles Substrate temp. (bottom) 600 ºC
Substrate material F82H steel Coating material
tungsten (100µm-thick) Specimen size 25 x 25 x 5
(mm)
10
Thermal Fatigue Testing
  • IR testing closely matches stress state at
    interface.
  • Flexural tests will be performed on samples that
    incorporate the W armor and substrate to quantify
    the mechanical strength of the interface at
    different cycle durations and following thermal
    aging.

Stress (MPa)
Blachard results
Depth (mm)
11
Thermal Fatigue Testing
W coated specimen
Cooling table
Rep rate 10Hz Max. flux 20.9MW/m2 (20ms) Min.
flux 0.5MW/m2(80ms) Duration 1000
cycles Substrate temp. (bottom) 600 ºC
Substrate material F82H steel Coating material
tungsten (100µm-thick) Specimen size 25 x 25 x 5
(mm)
12
W Coated F82H After Thermal Fatigue Testing
Diffusion Bonded
As Deposited
1000 shot, 20 MW/m2
Plasma Sprayed
No obvious degradation of adhesion of W to
F82H following fatigue testing For these
fatigue tests, carbide dissolution indicating
interface gt900C
13
W Coated F82H After 10,000 Cycle Fatigue Testing
  • In interface over-temperature (gt900C) a W-Fe
    intermetallic forms.
  • Formation of W-Fe brittle phase will likely lead
    to interface fracture and coating failure.
  • Isothermal aging experiments will be performed on
    W / F82H samples to demonstrate the temperature
    and time limitations of the interface.

W
FeW
F82H Steel
14
Thermal Fatigue Facility Upgrades for Prototype
Testing (complete 2005)
Continuous operation 1 msec, 5 Hz at 100
MW/m2 300 cm2 surface area irradiation
Front surface temperature monitoring
Fabrication of cooled prototype plasma spray
tungsten armored low-activation ferritic
15
Helium Management
At room temp. growth of He bubbles beneath the
surface causes blistering at 3 x 1021/m2 and
surface exfoliation at 1022/m2. For IFE power
plant, MeV He dose gtgtgt 1022/m2 .

First Wall Armor
MeV Helium
vacancy
MeV Helium
0 1 2 3 4 5 6
7 8 9 10
Time of microseconds
16
Effect of Iterative Implant/Anneal on Retained
Helium
A series of implantation to 1019 He/m2 for 1,
10, 100 and 1000 cycles has been completed
1.3 MeV He implantation Poly-X tungsten
target Resistive Heating
17
Effect of Iterative Implant/Anneal on Retained
Helium
Implantation to 1019 He/m2 for 1, 10, 100 and
1000 cycles
1.3 MeV He implantation Poly-X tungsten
target Resistive Heating
18
Determination of critical step size
Total 3He dose (1019 He/m2) Proton Yield (?10)
1 10
2 13
3 70
5 2000
10 7100
  • For Single-X W critical step size 31016
  • Helium doses implanted at 850C and
    flash-annealed at 2000C in 1000 cycles

19
Update on Effect of Peak Annealing Temperature
2000C
2500C
Single x annealed at 2500C shows
significantly less He retention than 2000C
anneal. Annealing temperature plays a
significant role in retained He and critical
dose. As part of the chambers study we need to
make precise assessment of implantation and
annealing temperatures to focus experiment.
20
Concluding Remarks
  • The HAPL program has selected refractory
    armored low-activation
  • ferritic steel as its prime candidate first
    wall.
  • Currently, optimization of the plasma-sprayed
    W/F82H steel in near
  • completion and mechanical testing underway.
  • IFE-unique critical-issues are being pursued
  • - X-ray and ion ablation and roughening (Renk
    and Latkowski)
  • - thermal fatigue of tungsten ferritic
    interface
  • - long-term thermal stability
  • - helium management
  • Special issue of Journal of Nuclear Materials on
    subject of
  • HAPL chamber currently being assembled.

21
Fabrication Process W/SiC
SiC without coating
IR processing
Tungsten Powder
W coating
Interface
SiC
10µm
SiC was removed by sublimation of the surface of
the SiC prior to ordering the W powder melt.
Rough interface was formed.
22
The Path to Develop Laser Fusion Energy
  • Scalable Technologies
  • Krypton fluoride laser
  • Diode pumped solid state laser
  • Target fabrication injection
  • Final optics
  • Chambers materials/design

Phase I Basic fusion science technology 1999-
2005
  • Target Design Physics
  • 2D/3D simulations
  • 1-30 kJ laser-target expts

Phase II Validate science technology 2006 - 2014
  • Full Scale Components
  • Power plant laser beamline
  • Target fab/injection facility
  • Power Plant design
  • Ignition Physics Validation
  • MJ target implosions
  • Calibrated 3D simulations

? Full size laser 2.4 MJ, 60 laser lines ?
Optimize targets for high yield ? Develop
materials and components. ? ? 300-700 MW net
electricity ? Resolve basic issues by 2028
Phase III Engineering Test Facility operating ?
2020
23
Chamber Progress -1 Operating windowsEstablishing
Chamber operating windows is a
multidisciplinary, simulation intensive,
process...........Here is an example for a 154
MJ target.
UCSD Wisconsin LLNL GA
24
Summary of Thermal Fatigue Experiment
  • Thermal fatigue experiments were carried out
    successfully using IR processing facility.
    Preliminary results showed tungsten coating was
    stable following the heat load (10Hz, 23.5MW/m2
    (10ms), 1000cycles).

25
Candidate First Wall Structure W/LAF (W/SiC
Backup)
Development of Armor fabrication process and
repair He management mech. thermal fatigue
testing Surface Roughening/Ablation Underlying
Structure bonding (especially ODS) high cycle
fatigue creep rupture Armor/Structure
Thermomechanics design and armor thickness finite
element modeling thermal fatigue and
FCG Structure/Coolant Interface corrosion/mass
transfer coating at high temperature? Modeling
Irradiation Effects swelling and embrittlement
Porous W Structure
Monolithic W
Liquid Metal Helium,or Salt Coolant?
LAF(600C max) or ODS(800C) structure,
possibly both.
26
Helium Management (ORNL, Delft, UNC)
Parametric Study Variables

Techniques
Data

Materials Temp. Dose
Single-X Irrad. Temp Total Dose Nuclear
Reaction Analysis N He,
retention Poly-X Anneal Temp Dose
Increment Thermal Desorption
Diffusivity/Activation Energy CVD Anneal
Rate TEM/SEM Defect size and
distribution Foam
weak dependence on material type
strong dependence on implantation temperature
annealing from 800-2000C diffuses
significant helium ----gt there are knobs to
turn that delay exfoliation in W
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