I di ti Eff t i Mt il Irradiation Effects in Materials for Nuclear Applications William J. Weber Professor and Governor’s Chair Professor and Governor s Chair Department of Materials Science & Engineering University of Tennessee Knoxville, TN 37996, USA MINOS Workshop Materials Innovations for Nuclear Optimized Systems CEA INSTN S l F CEA-INSTN Saclay , France December 5-7, 2012
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I di ti Eff t i M t i lIrradiation Effects in Materialsfor Nuclear Applications
William J. WeberProfessor and Governor’s ChairProfessor and Governor s Chair
Department of Materials Science & EngineeringUniversity of Tennessee
Knoxville, TN 37996, USA
MINOS WorkshopMaterials Innovations for Nuclear Optimized Systems
CEA INSTN S l FCEA-INSTN Saclay, FranceDecember 5-7, 2012
Nuclear Radiation Environments of InterestNuclear Radiation Environments of Interest
Fusion ReactorNuclear (Fission) Power
Nuclear Waste
Radiation Damage in Nuclear MaterialsRadiation Damage in Nuclear Materials Fundamental Radiation Damage Processes Nuclear Fuel (in reactor)( )
Fission Damage Accumulation of Fission & Transmutation Products
Structural Components Structural Components Fast Neutron Damage Helium & Hydrogen Production Other Transmutation ProductsOther Transmutation Products
Nuclear Waste Forms and Used Nuclear Fuel Fission Damage (negligible) Beta Decay Damage (important in short term <600 years) Beta Decay Damage (important in short-term – <600 years) Alpha Decay Damage (important over long-term – million years)
Use of Ion Beams to Study Radiation Damage Processes
Defect Production from Ballistic ProcessesPKA
BecomesInterstitial
Defect
PrimaryKnock-on
Atom(PKA)Defect
LeavesVacancyBehind
(PKA)
Behind
NeutronsIons
El t
Energetic neutrons, ions and electrons displace atoms Energetic Primary Knock-on Atoms (PKAs) create a cascade of
Electrons
Energetic Primary Knock-on Atoms (PKAs) create a cascade of ballistic collisions between atoms
Radiation Damage in Nuclear Materials Primarily Caused by Energetic Ions
created by Fission Fast Neutroncreated by Fission, Fast NeutronCollisions, or Radioactive Decay
Using Ion Beams to Study Irradiation Effects in Nuclear Materials has become a
Wid l P ti d A hWidely-Practiced Approach (particularly with lack of fast neutron test facilities)
Important for separate effects studies Use for development & validation of predictive models Offers wider range & more control of irradiation conditions Offers wider range & more control of irradiation conditions
Grand AccélérateurGrand Accélérateur National d’Ions Lourds
Fission Damage
Nuclear Fission
n (MeV)
235U
Bang
75 - 110 amu120 - 160 amu
n (MeV)(99Mo)
80 - 110 MeV ions(140Xe)
40 - 80 MeV ions
Fission products (high-energy ions) lose energy creating linear tracks of defects or structural changes in materials
Ballistic collision cascade near end of rangeg Fission tracks: nano radii (~ 5 nm) and macro lengths (~10 microns) Accumulation of fission products & gases affects microstructure In ~0.2 to 0.4% of fission events, helium is produced (ternary fission) In 0.2 to 0.4% of fission events, helium is produced (ternary fission)
Fission Product Energy Loss
V/nm
)20 Electronic
Energy LossLo
ss (k
eV
10
15 UO2Typical Fission Product
Ene
rgy
0
5 NuclearEnergy Loss
Projected Range (microns)0 2 4 6 8
0
Electronic Energy Loss: 1) ~20,000 defects along fission track (MD Simulations)2) Dislocation loops along fission track
Nuclear Energy Loss: 1) ~ 65,000 displaced atoms in fission product cascade2) Defect clusters in cascade
Radiation Damage in Nuclear Fuelg
Radiation Damage in 244Cm-doped Ca2Nd8(SiO4)6O2
0.25 m Fission Tracks from Spontaneous Fission Alpha-Recoil Tracks (95 keV 240Pu) from Alpha Decay Alpha Recoil Tracks (95 keV Pu) from Alpha Decay
Weber & Matzke, Mater. Lett. 5 (1986) 9-16
Studying Fission Damage with Swift-Heavy Ions
Target
Nanoscale, Linear and Parallel Structures
~100 MeVto
Target
to~2 GeV
Heavy Ions
apatite micaapatite mica
Leo A Kim et al., Neuron 41, 513 (2004)Weixing Li et al., EPSL 302, 227 (2011)
Simulating Fission Tracks with Swift-Heavy Ions
1.43 GeV Xe+ Tracks in Gd2TixZr2-xO7
(a) (b) (c)
Bright-Field TEM Images
30 nm 30 nm 30 nm
Gd2Ti2O7 Gd2TiZrO7 Gd2Ti0.5Zr1.5O7
Swift Heavy Ions Tracks are similar to Fission Tracks
Maik Lang et al. Phys. Rev. B 79, 224105 (2009)
Swift Heavy Ions Tracks are similar to Fission Tracks
MD Thermal Spike Simulation(J. Zhang et al., J. Mater. Res. 25, 1344 (2010))
2 nm
(M. Lang et al. Phys. Rev. B 79,224105 (2009))
(J. Zhang et al., J. Mater. Res. 25, 1344 (2010))
Neutron Damage in Nuclear ReactorsgIrradiation-Induced Growth
Core ComponentsIrradiation-Induced
CrackingIrradiation-Induced
Cracking
Neutron Spectra vs Monoenergetic Ion Beam
Fast NeutronFast NeutronSpectra
Thermal & Fast Neutron Irradiation
Other Considerations
f f ( ) Production of Helium and Hydrogen from (n,) and (n,p) nuclear reactions
Promotes void and bubble formation
Accumulation of Transmutation and Decay Products (changes in chemistry of materials)(changes in chemistry of materials)
Accumulation of Helium, Hydrogen, and y gTransmutation/Decay Products can be simulated to some extent with Multiple Ion Beams
Protons vs Neutrons: GB SegregationNote Temperature Difference
Protons can provide reasonablep
simulation of effects from mixed
(thermal/fast) neutron spectraneutron spectra
G.S. Was, Fundamentals of Radiation Materials Science (Springer, 2007)
Protons vs Neutrons: Loop FormationNote Temperature Difference
G.S. Was, Fundamentals of Radiation Materials Science (Springer, 2007)
Fast Neutron Damage
Radiation Damage from Fast NeutronsPrimary
Knock-onAtomAtom(PKA)
Fast NeutronFast Neutrons undergo “Hard-Sphere”
Collisions with Atoms in SolidsFission: ~1 MeV
Fusion: 14.1 MeV
Fission PKAs: 50 to 300 keV Ions Fusion PKAs: up to several MeV Ions
Defect Microstructures in Irradiated MaterialsV id Helium bubbles
(grain boundaries)
Voids, precipitates,
solute segregationPoint defect accumulation
Dislocation loop formation
50 nm50 nm
Irradiation Temperature (T/TM)0.2 0.3 0.4 0.5 0.6
Swelling Changes due to Temperature & Dose(Neutron Irradiation)(Neutron Irradiation)
NoVoids
LargestVoids
Temperature Shift of Void Growth Rateith D R twith Dose Rate
Neutrons Ions
G.S. Was, Fundamentals of Radiation Materials Science (Springer, 2007)
Void Free Regions & Void Size/Density Changes near Grain Boundaries in neutron-irradiated Cunear Grain Boundaries in neutron-irradiated Cu
1 dpa
Zinkle & Farrell, J. Nucl. Mater. 168 (1989) 262
Effect of Grain Boundaries in VanadiumIon Irradiated at 500°C to 1 dpa
Larger Voids Near Grain Boundaries
W.J. Weber, PhD Thesis, 1977
Void and Helium Bubble Lattices
3-D Void Lattice in Nb
3-D Bubble Lattice in Mo
27
G.S. Was, Fundamentals of RadiationMaterials Science (Springer, 2007)
Weighted Recoil Spectra for Ions in Ni
W(T) = Fraction of defects produced by recoils of energy less than T
Nastasi et al. Ion-Solid Interactions (Cambridge, 1996), p. 169
W(T) = Fraction of defects produced by recoils of energy less than T
Weighted Recoil Spectra for 1 MeV Particles in Cu
Fast Neutrons produceproduce different
recoil spectra than Protonsthan Protons
G.S. Was, Fundamentals of Radiation Materials Science (Springer, 2007)
Comparison of Damage from 1 MeV Particles in Ni
G.S. Was, Fundamentals of Radiation Materials Science (Springer, 2007)
Alpha-Decay Damage
Alpha-Decay Damage in Materials
AlphaParticle
RecoilNucleus
235U
Alpha-Recoil Nucleus 70 - 100 keV ions
Alpha-Particle 4.5 - 5.8 MeV ions
235U
30 - 40 nm Range Creates More Damage
(~2000 Displaced Atoms)
16 - 22 m Range Creates Less Damage
(~350 Displaced Atoms)
Atomic Collision Damage from Recoil Nucleus and Alpha Particle (both are energetic ions)
Helium accumulation
Self-Radiation Damage in 244Cm-doped Gd2Ti2O7
0.6 x 1018 -decays/g
100 nm
3.4 x 1018 -decays/gFission Tracks
Alpha-Recoil Tracks
y gAmorphous
From Weber, Wald & Matzke, J. Nuclear Materials (1986)
Dose Dependence: Large Time Scale Range
a)1.0
ract
ion
(f a
0 6
0.8 Gd2Ti2O7
rpho
us fr
0.4
0.6
Am
o
0.2 244Cm-doped (340 K)
Au-Irradiated (300 K)
Dose (dpa)0.0 0.1 0.2 0.3
0.0
Ion Irradiation (minutes) & alpha decay (years) results in excellent agreement
S Moll et al. Phys. Rev. B 84 (2011) 064115
Gd2Ti2O7: Temperature Dependence2 2 7 p p
pa) 0.8 Gd2Ti2O70.6 MeV Ar+
Dos
e (d
p
0.6 1.0 MeV Kr+
0.6 MeV Bi+
1.0 MeV Kr+
phiz
atio
n
0.4 1.24 wt % 244Cm
Am
orp
0 0
0.2
D = Do / [1 – (th/d) exp(-Eth/kT)]
Temperature (K)0 200 400 600 800 1000
0.0
Good agreement between Heavy-Ion Data and Alpha-Decay (244Cm) Data
WJ Weber and RC Ewing, MRS Symp. Proc. Vol. 713 (2002) p. 443
Such data can be used to predict long-term behavior of actinide waste forms
Model Predictions Based on Experiment Data
Equivalent Storage Time (years)
101 102 103 104 105
1.0 Ceramics with
100Ca239PuTi2O7
us F
ract
ion
0.6
0.8
Gd2Ti2O7
Ceramics with10 wt% 239Pu
Gd2ZrTiO7
atio
n D
ose
deca
ys/g
)
10
Ca PuTi2O7
Gd2ZrTiO7
Am
orph
ou
0.2
0.4
Gd2Zr2O7Am
orph
iza
(1018
-d 10 2 7
(10 wt% 239Pu)Gd2Ti2O7
(10 wt% 239Pu)
R it T t
Dose (alpha-decays/g)1016 1017 1018 1019 1020
0.0
Temperature (K)300 400 500 600 700
1Repository Temperatures
Temperature Dependence Dose/Time Dependence
Ewing, Weber & Lian, J. Appl. Phys. 11 (2004) 5949-5971
Summary on Use of Ion Beams to StudyR di ti Eff t i N l M t i lRadiation Effects in Nuclear Materials
Be aware of dose rate effects (temperature shifts)
Be aware of mass difference effects (recoil spectra)
Ion irradiations should complement in-reactor testing or th b lk i di ti ( h t li d ti id )other bulk irradiation (short-lived actinides)
Ion irradiation studies can be used to guide in-reactor or bulk irradiation testing for model validationor bulk irradiation testing for model validation
Ion beams can be used to more precisely control irradiation conditions and parameters to study separate ad at o co d t o s a d pa a ete s to study sepa ateeffects and develop/validate models
Ion beams can be used to achieve high doses currently unachievable (structural materials and waste forms)