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1 Managed by UT-Battelle for the U.S. Department of Energy
Materials for Advanced Fission and Fusion Reactors
Steve Zinkle Nuclear Science & Engineering Directorate
Oak Ridge National Laboratory
NE50: Symposium on the Future of Nuclear Energy
School of Nuclear & Radiological Engineering & Medical Physics
Georgia Tech, Atlanta, GA
November 1, 2012
2 Managed by UT-Battelle for the U.S. Department of Energy
Timeline of some key events for nuclear energy and materials and computational science
1940 1950 1960 1970 1980 1990 2000 2010
CP-1 Graphite
Shippingport
Development of Mat. Sci.
as an academic discipline
reactor JET: Q=0.65, 0.5s
1 Gflops achieved;
high performance
computing centers
established
1 Tflops 1 Pflops
Nuclear >10%
US electricity
ENIAC
Tokamak era begins
ITER
NIF
1st stellarator
& Tokamak
1st MD simulation of radiation damage
(500 atoms, 1 min. time step)
multimillion atom MD simulations
(~1 fs time step)
TFTR: Q=0.27 JT-60:
Qeq=1.25
3 Managed by UT-Battelle for the U.S. Department of Energy
US Reactor Fuel Performance: Higher burnup with fewer failures
Zinkle & Was, Acta Mater., in press
4 Managed by UT-Battelle for the U.S. Department of Energy
Materials performance is key for economic and safe fission reactor operation in current LWRs
• Heat generation in UO2-based fuel pellets to high burnup
• Heat transfer across Zr alloy cladding; fission product containment under normal and design-basis transient conditions
• Numerous core internal structures to securely position core
• Reactor pressure vessel for containment of fission products
• Piping and steam generator equipment for heat conversion to electricity
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ARIES-AT Magnetic Fusion Energy concept
F. Najmabadi et al. Fus. Eng. Des. 80 (2006) 3
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New technology, New requirements
Gen-III
Pressurized
Water Reactor
Gen-IV
Fast Reactor
Very High
Temperature
Reactor
Coolant Water Sodium Helium
Power Density (MW/m3) 100 350 5
Coolant Temp. (C) 330 550 1000
Net Plant Efficiency (%) 34 40 50
7 Managed by UT-Battelle for the U.S. Department of Energy
Comparison of Gen IV and Fusion Structural Materials Environments
fusion SiC
V alloy, ODS steel
F/M steel
All Gen IV and Fusion concepts pose
severe materials challenges
S.J. Zinkle & J.T. Busby, Mater. Today 12 (2009) 12
S.J. Zinkle ,OECD NEA Workshop on Structural
Materials for Innovative Nuclear Energy Systems,
Karlsruhe, Germany, June 2007
8 Managed by UT-Battelle for the U.S. Department of Energy
Radiation Damage can Produce Large Changes in Structural Materials
• Radiation hardening and embrittlement (<0.4 TM, >0.1 dpa)
• Phase instabilities from radiation-induced precipitation (0.3-0.6 TM, >10 dpa)
• Irradiation creep (<0.45 TM, >10 dpa)
• Volumetric swelling from void formation (0.3-0.6 TM, >10 dpa)
• High temperature He embrittlement (>0.5 TM, >10 dpa)
100 nm
50 nm
100 nm S.J. Zinkle, Phys. Plasmas 12 (2005) 058101; Zinkle & Busby, Mater. Today 12 (2009) 12
9 Managed by UT-Battelle for the U.S. Department of Energy
Examples of radiation damage degradation
Zinkle & Was, Acta Mater., in press
Contributor to SCC in LWR internals Stainless steels are not attractive options
for high dose Gen IV reactor applications
Tirr=420-580oC
10 Managed by UT-Battelle for the U.S. Department of Energy
There are many approaches for radiation resistance
high density of nanoscale precipitates or particles (e.g., ODS steel or Ti-modified austenitic stainless steel)
L.K. Mansur & E.H. Lee, J. Nucl. Mater. 179-181 (1991) 105
Fe-13Cr-15Ni CW (P,Si,Ti,C)-modified High mag of “b”
Operation at temperatures where vacancies are immobile (e.g., SiC composites)
Current LWR core internals
Gen IV SFR core internal structures
after S.J. Zinkle, Chpt. 3 in Comprehensive Nuclear Materials (Elsevier, 2012)
11 Managed by UT-Battelle for the U.S. Department of Energy
Heat to Heat Variability has been a Common Feature of Structural Alloys
Heat 1
Heat 2
Heat 3
13.5 N-mm-2
helium
Time (hrs)
Heat 1
Heat 2
Heat 3
5000 10000 15000 20000
Cre
ep s
train
(%
)
13.5 N-mm-2
helium
P.J. Ennis et al. 1984
Alloy 617 Thermal Creep
12 Managed by UT-Battelle for the U.S. Department of Energy
New steels designed with computational
thermodynamics exhibit superior mechanical
properties compared to conventional steel
• Three experimental RAFM heats (1537, 1538, and 1539), together with an optimized-Gr.92 heat (C3=mod-NF616), were investigated
• Tensile strength of new TMT steels were much higher than conventional steels
• Dramatic improvement in thermal creep strength also observed
0 100 200 300 400 500 600 700 800
200
400
600
800
NF616
1537
1538
1539
Mod-NF616
Yie
ld S
trength
(M
Pa)
Temperature (oC)
PM2000
F82H
0 100 200 300 400 500 600 700 8000
5
10
15
20
25
30
35
40
1537
1538
1539
Mod-NF616
Tota
l E
long
atio
n (
%)
Temperature (oC)
PM2000
NF616
L. Tan et al. (2012)
1.6X
13 Managed by UT-Battelle for the U.S. Department of Energy
Modern steels exhibit reduced hardening and less
embrittlement compared to 1960s-era RPV steel
To = 0.3
y RAFM
To = 0.7
y RPV
YIELD STRENGTH INCREASE, MPa
0 100 200 300 400 500 600T
o SHIFT, oC
0
50
100
150
200
250
F82H-IEA
F82H-HT2
9Cr-2WVTa
Eurofer97(Lucon, SCK-CEN)
Eurofer97(Rensman, NRG)
RPV Steels
(Sokolov, ASTM STP 1325)
T0 s
hif
t, o
C
Embrittlement rate of modern steels
is about 40% that of RPV steels
(normalized to same amount of
radiation hardening)
M.A. Sokolov et al., J. Nucl. Mater. 367-370 (2007) 68 J. Rensman, NRG report 20023/05.68497/P (2005);
M. Lambrecht et al., J. Nucl. Mater. 406 (2010) 84
Hardening rate of modern steels is
about 50% that of RPV steels
RPV steel
Plotted data are 8-9%Cr steels; similar results obtained for
pressure vessel-relevant steels such as modern 2-3%Cr steels
14 Managed by UT-Battelle for the U.S. Department of Energy
Advanced Manufacturing Techniques offer the potential to enable rapid fabrication of complex geometries
Examples of additive manufacturing technologies
15 Managed by UT-Battelle for the U.S. Department of Energy
High
temperature
during loss of
active cooling
Improved Cladding Properties to
maintain core coolability and retain
fission products
-High temperature clad strength and
fracture
-Thermal shock resistance
-Resistance to melting
-Resistance to hydrogen embrittlement
Improved Fuel Properties
-Lower operating temperatures
-Clad internal oxidation
-Fuel relocation / dispersion
-Enhanced retention of fission
products
-Fuel melting safety margin
Suppressed Reaction Kinetics with Steam
to minimize enthalpy input and hydrogen
generation
-Oxidation rate
-Heat of oxidation
There are three major potential strategies for
accident tolerance
• potential options for fuel cladding include:
– Oxidation-resistant austenitic steels
– Oxidation-resistant coatings on Zr alloy cladding
– Ceramic matrix composite cladding
16 Managed by UT-Battelle for the U.S. Department of Energy
Thermal creep strength of some candidate cladding materials
• Mo alloys and steels (and SiC/SiC, not plotted) offer improved high temperature strength
17 Managed by UT-Battelle for the U.S. Department of Energy
High-Pressure Steam Oxidation Tests: Comparison of the Extent of Steam Reaction Various materials exposed to pure steam for 8 hours (various flow rates and pressures):
• Zircaloy: Pawel-Cathcart and Moalem-Olander data
• 317 Stainless Steel: ORNL high-pressure tests; thickness loss data
• NITE and CVD SiC: ORNL high-pressure tests; thickness loss data
• 310 Stainless Steel: ORNL high-pressure tests; mass gain data converted to
thickness loss
• FeCrAl Ferritic Steel: ORNL high-pressure tests; mass gain data converted to
thickness loss
0.1
1
10
100
1000
750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350
Mate
rial
Recessio
n [
µm
]
Temperature [ C]
18 Managed by UT-Battelle for the U.S. Department of Energy
Several Accident Tolerant Fuel Concepts
are Under Consideration, including:
• UO2 – Zircaloy (Base Case)
• UO2 – FeCrAl (oxidation resistant Steel)
• FCM – FeCrAl Fully Ceramic
Microencapsulated Fuel
UO2
Pellet
Zircaloy
Cladding
Conventional LWR UO2 Rod
Coated
Fuel
Particle
Cladding
(Zircaloy,
Steel, SiC)
LWR FCM Rod
FCM
Pellet
TRISO
Fuel
Particle
19 Managed by UT-Battelle for the U.S. Department of Energy
There are numerous proposed fusion blanket technology options, all of which are at a relatively immature TRL
• Key issues include tritium recovery/transport, coolant compatibility, safety, waste disposal/recycling, radiation damage effects, and lifetime limits
• The 3 leading structural materials candidate systems are ferritic/ martensitic steel, V alloys, and SiC/SiC (based on safety, waste disposal, and performance considerations)
• These blanket concepts would utilize a variety of conceptually interesting (but unproven on engineering scale) tritium recovery processes
Structural
Material
Coolant/Tritium Breeding Material
Li/Li He/PbLi H2O/PbLi He/Li ceramic H2O/Li ceramic FLiBe/FLiBe
Ferritic s teel
V alloy
SiC/SiC
20 Managed by UT-Battelle for the U.S. Department of Energy
Fusion energy research is approaching a transition from plasma science to fusion engineering science
Option A: IFMIF + fission reactors +ion beams + modeling
Option B: robust spallation (e.g., MTS) + fission reactors + ion beams + modeling
Option C: modest spallation (e.g.,SNS/SINQ) + fission reactors + ion beams + modeling
• An intense neutron source (in concert with enhanced theory and modeling) is proposed to improve understanding of basic fusion neutron effects and to develop & qualify fusion structural materials
New facilities would expand current
knowledge base on ferritic steels
21 Managed by UT-Battelle for the U.S. Department of Energy
Detailed timeline of some key facilities for nuclear energy and materials
1942 1944 1946 1948 1950 1952 1956 1958
CP-1
Shippingport
ORR
Obninsk
AM-1
1st radiation damage paper
E.P. Wigner
J. Appl. Phys. 17 (1946) 857
1954
MTR
BSR Graphite
reactor
ETR
Calder
Hill
CP-5
BGRR
22 Managed by UT-Battelle for the U.S. Department of Energy
Conclusions
• The impact of materials on the future of fission and fusion energy is pronounced
– New materials for improved accident tolerance and core structures of light water fission reactors; Several potential candidates for improved accident tolerance exist, but further R&D is needed to examine behavior under normal and potential accident scenarios
– Existing structural materials face Gen IV fission and fusion reactor design challenges due to limited operating temperature windows
– May produce technically viable design, but not with desired optimal economic attractiveness
• Substantial improvement in the performance of structural materials can be achieved in a timely manner with a science-based approach
– e.g., Design of nanoscale features in structural materials confers improved mechanical strength and radiation resistance
– Selection of accident-tolerant fuel options for light water fission reactors
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