Transcript Document 7332394

Materials Issues, Gaps and
Research Needs
RJ Kurtz1 and the ReNeW Materials Panel
1Pacific
Northwest National Laboratory
Harnessing Fusion Power Workshop
Los Angeles, CA
March 2 - 4, 2009
ReNeW Materials Panel Members
Name
Rick Kurtz, Leader
Mike Mauel
Affiliation
PNNL
Columbia
Email
[email protected]
[email protected]
Mike Nastasi
LANL
[email protected]
Bob Odette
UCSB
[email protected]
Shahram Sharafat
UCLA
[email protected]
Roger Stoller
ORNL
[email protected]
Steve Zinkle
ORNL
[email protected]
Greenwald Panel Materials Issues
Overarching Issue: Understand the basic materials science phenomena for
fusion breeding blankets, structural components, plasma diagnostics, and
heating components in high neutron areas.
Issue
Description
MI-1
Constitutive mechanical properties of structural and breeding blanket materials after thermal and
irradiation exposure including joints and dissimilar material transition regions.
MI-2
Dimensional and phase stability of structural and breeding material systems due to neutron
irradiation.
MI-3
Scientific basis for high-temperature design criteria.
MI-4
Quantitative predictive model for thermal conductivity degradation of neutron irradiated metals and
ceramics.
MI-5
Physical mechanisms controlling the chemical dissolution of materials exposed to coolants, including
mass transfer phenomena associated with surrounding dissimilar solid materials.
MI-6
Mechanisms responsible for radiation-induced changes in electrical resistance and optical properties
in dielectric materials.
MI-7
Exploration of reduced-activation and reduced-decay-heat compositions that simultaneously provide
high structural material performance.
Greenwald Panel Materials Gaps
Gap
Description
GM-1
Predictive multiscale models of materials behavior in the fusion environment.
GM-2
Constitutive mechanical properties of structural and breeding blanket materials in the
fusion environment.
GM-3
Dimensional and phase stability and physical property degradation in the fusion
environment.
GM-4
Science basis for robust high-temperature design criteria.
GM-5
Chemical compatibility of materials in the fusion environment.
GM-6
Fabrication and joining of complex structures.
ReNeW Panel Materials Issues
Issues
Systems
Components
Alloy Development
FW/Blanket/Shield, Vacuum
Vessel, Divertor/PFC
Structural & HHF Materials
Chemical Compatibility
FW/Blanket/Shield, Vacuum
Vessel, Divertor/PFC
Structural & HHF Materials, Tritium Breeding & Neutron
Multiplier Materials, Tritium Extraction, HX & Piping
Design Criteria
FW/Blanket/Shield, Vacuum
Vessel, Divertor/PFC, Magnets
Structural & HHF Materials, Neutron Shielding, Tritium
Extraction, HX & Piping, Magnet Materials
Erosion
Divertor/PFC
HHF Materials
Fabrication & Joining
FW/Blanket/Shield, Vacuum
Vessel, Divertor/PFC
Structural & HHF Materials, Neutron Shielding, Tritium
Extraction, HX & Piping
Plasma-Material Interactions
Divertor/PFC
HHF Materials
Radiation Effects
FW/Blanket/Shield, Vacuum
Vessel, Divertor/PFC, Magnets,
Functional
Structural Materials, Tritium Breeding & Neutron Multiplier
Materials, HHF Materials, Magnet Materials, Plasma
Diagnostic Materials, Optical Materials, Mirrors
Safety, Licensing, RAMI
FW/Blanket/Shield, Vacuum
Vessel, Divertor/PFC
Structural & HHF Materials
Thermal Creep & Fatigue
FW/Blanket/Shield, Vacuum
Vessel, Divertor/PFC
Structural & HHF Materials, Tritium Breeding & Neutron
Multiplier Materials
Tritium Inventory
FW/Blanket/Shield, Divertor/PFC
Tritium Breeding & Neutron Multiplier Materials, Tritium
Extraction, HX & Piping, HHF Materials
Tritium Permeation
FW/Blanket/Shield
Tritium Breeding & Neutron Multiplier Materials, Tritium
Extraction, HX & Piping
Materials Research and the Path to
Fusion Power
Plasma Physics
Confinement
Fusion Reactor
Concept
Definition
ITER
DEMO
Conceptual
Designs
 Materials research to identify candidate materials
-
Radiation damage
Activation
Mechanical & physical properties
Compatibility with coolants and tritium breeders
Large-scale fabrication & joining issues
 Identify and demonstrate approaches to improve
material performance
 Identify concept specific issues and demonstrate proofof-principle solutions, e.g.
- Design with ferromagnetic material
- Methods for design of large, thermo-mechanically loaded
structures
Ion Accelerators
RTNS
Fission Reactors
IFMIF
 Development of materials with acceptable performance
Component Test
and demonstrate to goal life (dpa, He)
Facilities
 Demonstrate solutions to concept specific issues on
actual structural materials and prototypic components
DEMO Final
Actual Fusion
 Develop design data base, constitutive equations, and
Design &
Environment
models to describe all aspects of material behavior
required for design and licensing
Construction
Test Results
Key need is close integration of materials science with the structural analysis-design process.
Current Development Status of
Fusion Structural Materials
Feasibility
Concept
Exploration
RAF/M Steels
Unirradiated
Irradiated
V Alloys
Unirradiated
Irradiated
NFA Steels
Unirradiated
Irradiated
SiC/SiC
Unirradiated
Irradiated
W Alloys
Unirradiated
Irradiated
Tech. maturation
Proof of
Principle
Performance
Extension
Low-Activation Structural Materials
for Fusion
 Materials strongly impact
economic & environmental
attractiveness of fusion power
- basic feasibility.
 Many materials are not
suitable for various
reasons.
 Based on safety, waste
disposal and performance
considerations, the three
leading candidates are:
RAF/M and NFA steels
Tungsten alloys
SiC composites
Low-activation is a must!!
None of the current reduced or lowactivation fusion materials existed 15 years
Fusion Materials Relies Heavily on Modeling due
to Inaccessibility of Fusion Operating Regime
Extrapolation to fusion regime is much larger for the fusion materials
than for plasma physics program.
Lack of an intense neutron source emphasizes the need for a
coordinated scientific effort combining experiment, modeling and theory
to a develop a fundamental understanding of radiation damage.
He and Displacement Damage Levels
Steels
Spallation
neutrons
ITER
Fusion
reactor
IFMIF
Impact of He-Rich Environment on
Neutron Irradiated Materials
 A unique aspect of the DT fusion environment is substantial
production of gaseous transmutants such as He and H.
Grain boundary
 Accumulation of He can have major implications for the integrity of
fusion structures such as:
- Loss of high-temperature creep strength.
- Increased swelling and irradiation creep at intermediate temperatures.
- Potential for loss of ductility and fracture toughness at low temperatures.
1000
Time to rupture, h
316 SS @ 750°C & 100 MPa
100
10
1
Un-implanted
200 appm He
Science-Based High-Temperature
Design Criteria


Current high-temperature design methods are
largely empirical.
Cyclic plastic loading is far more damaging than
monotonic loading.
New models of high-temperature deformation and
fracture are needed for:
• Creep-fatigue interaction.
• Elastic-plastic, time-dependent fracture mechanics.
• Materials with low ductility, pronounced anisotropy,
composites and multilayers.
J. Aktaa & R. Schmitt, FZK, 2004
3000
EUROFER 97
T=550°C t=1.0%
2500
NUMBER OF CYCLES TO FAILURE, Nf

2000
ZERO
HOLD-TIME
TENSION HOLD-TIME
1500
SYMMETRICAL HOLD-TIME
1000
COMPRESSION HOLD-TIME
600
10
100
TIME PER CYCLE, S
800
Breaking the High Strength-Low
Toughness/Ductility Paradigm
Theoretical Strength ~E/50
Future Materials
Strength
 Increased strength is
accompanied by reduced
toughness (cracking resistance)
and ductility.
 Strength is increased by alloying,
processing and radiation
damage.
 Low toughness and ductility
reduce failure margins.
 The benefits of simultaneously
achieving high-strength and high
ductility/ toughness would be
enormous.
Current Engineering
Materials
Toughness or Ductility
Fundamentals of Material-Coolant Chemical
Compatibility in the Fusion Environment
 The traditional approach to
corrosion is empirical.
 Correlations do not capture basic
physics and have limited
predictive capability.
 Opportunities:
 Controlled experiments
combined with physical
models utilizing advanced
thermodynamics & kinetics
codes.
 Integrated experiments using
sophisticated in situ diagnostic
and sensor technologies.
M. Zmitko / US-EU Material and Breeding Blanket Experts Meeting (2005)
J. Konys et al./ ICFRM-12 (2005)
Theory and Modeling of Materials
Performance Under Fusion Conditions
Integration of modeling-theory-experiments-database development is a
critical challenge in bridging the multi-physics-length-time scales.
• Success - simulations and
• Microstructural evolution in a
high-energy neutron, He-rich
environment.
• Resulting in degradation of
performance sustaining
properties and stability.
• Effects of He are critical.
experiments show high-energy
fusion damage events are similar
to multiple, lower-energy events provides fission-fusions dpa
damage scaling.
Comparison of 10 and 50
keV displacement
cascades in iron
50
keV
10
keV
100K, iron
Coupling of Modeling and Experiment
to Determine He Transport and Fate
Experimental characterization
SANS/
ASAXS
PAS
TEM
THDS
0.001
0.02
0.04 0.06
2
-2
q (Å )
0.08
0.1
TEM, SANS,
Positron theory
Multiscale modeling
Fe
self-consistent
‘understanding’
of He effects
He
predict
features
simulate
observables
GR Odette, UCSB & BD Wirth, UCB
(cm
) •ster
0
1
LMC: Nuclear
LMC: Nuc + Mag
SANS: Nuc
SANS: N+Mag
-1
0.0001
0 .1
-1
feature
‘signals’
0.1
0.01
d S/dW
-1
d /d [(cm•ster) ]
1
0. 01
0.0 01
0
0.01 0.02 0. 03 0.04 0.05 0.06
q2 (Å- 2 )
Compelling Scientific Needs - I
 Recent fusion materials R&D efforts have led to the development
of high-performance reduced-activation structural materials with
good radiation resistance for doses ~30 dpa and ~300 appm He.
 The overarching scientific challenge facing structural materials for
DEMO is microstructural evolution and property changes
(mechanical and physical) that may occur for neutron doses up to
~200 dpa and ~2000 appm He.
 Development of high-performance alloys and ceramics including
large-scale fabrication and joining technologies is needed.
 Current understanding of strength-ductility/toughness relationships
is inadequate to simultaneously achieve high-strength and highductility and toughness.
Compelling Scientific Needs - II
 Better mechanistic physical models of thermo-mechanical
degradation are needed for development of advanced materials
and science-based high-temperature structural design criteria.
 The mechanisms controlling chemical compatibility of materials
exposed to coolants and erosion of materials due to interaction
with the plasma are poorly understood.
 Better understanding of radiation-induced and thermomechanical property changes in high-heat flux materials
(tungsten), magnet, and a host of functional materials is required.
Critical Resource Needs - I

Research Scientists and Engineers
• Many specialized skills will be needed – physical metallurgists, ceramists,
electron microscopists, mechanical property specialists, fracture mechanics,
materials evaluation specialists (SANS, PAS, APT, etc.), corrosion scientists,
nondestructive evaluation specialists, theory and modeling experts (multiscale
materials modeling).
2003 FESAC Development Plan estimated ~60 FTE/y at peak activity.
Existing talent pool rapidly shrinking!
•
•
 Materials Science Facilities
• Materials evaluation equipment – TEM, SEM, FIB, Auger, APT, etc.
• High-temperature materials testing – creep, fatigue, fracture, thermal-shock and
fatigue.
• Compatibility testing – flow loops for corrosion testing, oxidation.
• Physical property measurements – thermal, electrical, optical, etc.
• Material fabrication and joining of small to large-scale components.
• Hot cells for handling and testing of activated materials.
Critical Resource Needs - II

Non-Nuclear Structural Integrity Benchmarking Facilities
• Facilities for testing various components such as blanket modules are needed to
•
•
•

investigate the potential for synergistic effects that are not revealed in simpler
single-variable experiments or limited multiple-variable studies.
Provides data to refine predictive models of materials behavior.
Gives reliability and failure rate data on materials, components and structures to
valid codes for designing intermediate step nuclear devices and DEMO.
Test bed to test and evaluate nondestructive inspection techniques and
procedures.
Other Facilities
• Extensive computational resources will be needed at all phases of fusion
materials development to support model development but, in particular, largescale structural damage mechanics computational capability will be needed to
guide and interpret data obtained from component-level test facilities.
Critical Resource Needs - III

Fission Reactors
• The capability to perform irradiation experiments in fission reactors is essential
for identifying the most promising materials and specimen geometries for
irradiation in an intense neutron source.

Intense Neutron Source
• Overcoming radiation damage degradation is the rate-controlling step in fusion
•
•
materials development.
Evaluation of radiation effects requires simultaneous displacement damage
(~200 dpa) and He generation (~2000 appm).
International assessments have concluded that an intense neutron source with
≥ 0.5 liter volume with ≥ 2 MW/m2 equivalent 14 MeV neutron flux to enable
testing up to a least 10 MW-y/m2, availability > 70%, and flux gradients ≤
20%/cm is essential to develop and qualify radiation resistant structural
materials for DEMO.
Critical Resource Needs - IV
Component Test Facility
• Nuclear facility to explore the potential for synergistic effects in a fully integrated
fusion neutron environment. Data and models generated from non-nuclear
structural test facilities, fission reactor studies and the intense neutron source
will be needed to design this facility.