i diti eff t i mt ilirradiation effects in materials for nuclear … · 2012-12-17 · i diti eff t...

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

Some Experimental Research Facilities

ArgonneArgonneggNationalNationalLaboratoryLaboratory

University of TennesseeUniversity of Tennessee

Pacific NorthwestPacific NorthwestNational LaboratoryNational Laboratory

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

1.43 GeV Xe Track in Gd2Ti2O7

dE/dx = 28.5 keV/nm dE/dx = 12 keV/nm(No electron-phonon coupling efficiency)

2 nm 2 nm

HRTEM Image(M. Lang et al. Phys. Rev. B 79,

2 nm

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


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


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


Comparison of Damage from 1 MeV Particles in Ni


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)

i diti eff t i mt ilirradiation effects in materials for nuclear … · 2012-12-17 · i diti eff t...

Documents