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EDF. Electricité de France. RPV steels microstructure evolution under irradiation: a multiscale approach. Charlotte Becquart and. - PowerPoint PPT Presentation
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Cosires 2004 C.S. Becquart
RPV steels microstructure evolution under irradiation: a multiscale approach
Charlotte Becquart and...
EDFElectricitéde France
A. Barbu: CEA, C. Domain: EDF, S. Jumel: EDF, M. Hou: U.L.B, A. Legris: LMPGM, L. Malerba: SCK-CEN,J-M. Raulot, J-C. Van Duysen: EDF, A. Souidi: U. Saida, D. Bacon: U. Liverpool, M. Perlado: Polytech., M. Hernández-mayoral, CIEMAT, R. Stoller: ORNL, B. Wirth: LLNL, B. Odette: UCSB...
PhD and Master of Science students : P. Renuit, E. Vincent, S. Jumel, A. Marteel, P. Herrier, J-C. Turbatte, J-M Raulot, S. Pourchet, A. Tigeras, Z. Zhao
Cosires 2004 C.S. Becquart
Vessel
12 m
4.4 m
22 cm
Cosires 2004 C.S. Becquart
0
50
100
150
200
250
-200 -100 0 100 200 300
Temperature (°C)
En
erg
y (J
) baselineirradiated
DBTT shift (41 J level)
USE drop
Displacement
Lo
ad
Baseline
Irradiated
04 Oct 2001 29 Nov 2001
yield increase
DD
00
ll
00
Displacement
------ Baseline
------ Irradiated
Under irradiation: modification of the mechanical properties
===> hardening and embrittlementTDoseFluxComposition
C S P Si Cr Mo Mn Ni Al Co Cu
0.16 0.008 0.008 0.19 0.24 0.55 1.25 0.74 0.009 0.01 0.07
Chemical composition (wt.%) of DAMPIERRE 2
Cosires 2004 C.S. Becquart
SIA-Loop
NanovoidCu-rich ppt or atmospheres
P-segregation
Matrix
Damage
Precipitation
Segregatio
n
at GBs
Microstructural changes
Tomographic atom probe
Université de Rouen
V = 4 x 4 x 4 nm3
Fe-0.1%Cu , dose 5.5 1019n/cm2
Cosires 2004 C.S. Becquart
1.E+08
1.E+09
1.E+10
1.E+11
1.E+12
1.E-08 1.E-06 1.E-04 1.E-02 1.E+00 1.E+02
Eneutron (MeV)
Flux
(n/c
m2/
s)
SIA-Loops
NanovoidCu-rich ppt
P-segregation
Matrix
Damage
Precipitation
Segregatio
n
at GBs
?
0
50
100
150
200
250
-200 -100 0 100 200 300temperature (°C)
ener
gy (
J)
?
Necessary balance between simplifications and
approximations versus completeness and physical
detail
Cosires 2004 C.S. Becquart
Rapid overview of the REVE ’s VTR
The primary damage : role of the cohesive model
The evolution of the primary damage : parameterisation of the Object Kinetic Monte Carlo
Outline of the talk
Cosires 2004 C.S. Becquart
A. Seeger, Proc. 2nd UN Int. Conf. on Peaceful Usess of Atomic Energy, Geneva, 1958, vol.6 (United Nations, New York, 1958) p 250.
Cosires 2004 C.S. Becquart
- defect - dislocation interaction :
Screw DislocationDefect
Hardening
V-Cu clusters (s to h)
- Evolution - Primary damage
vacancies & interstitials (15 ps)
Microstructure
Clusters and loops
- PKA spectrum
Spectre de neutron
1.E+08
1.E+09
1.E+10
1.E+11
1.E+12
1.E-08 1.E-06 1.E-04 1.E-02 1.E+00
1.E+02
Flu
x (n
/cm
2/s)
1.E-08
1.E-05
1.E-02
1.E+01
1.E+04
1E-05 1E-04 1E-03 1E-02 1E-01 1E+00 1E+01
EPKA (MeV)
PK
A F
lux
(PK
A/µ
m3/M
eV/s
)
PWR
- neutron spectrum
Simplified overview of the REVE ’s VTR
Specter
Incas
Dymoka Lakimoca
Dupair
Cosires 2004 C.S. Becquart
VASP (Vienna Ab initio Simulation Package)
Density Functional Theory
Plane wave & ultra soft pseudo potentials (Vanderbilt type pseudo potentials)
Exchange and correlation: LDA and GGA (PW91)
Spin polarised
54 atoms (555 k points) – 128 atoms (333 k points)
all atomic positions for defects calculation are relaxed
Methods and cohesive models
Ab initio
Semi-empirical potentials (FeCu)
M. Ludwig, D. Farkas, D. Pedraza and S. Schmauder, Modelling Simul. Mater. Sci. Eng, 6 (1998) 19
G.J. Ackland, D.J. Bacon, A.F. Calder and T. Harry Phil. Mag. A, vol.75 (1997) 713
VASP:
G. Kresse and J. Hafner, Phys. Rev. B 47, 558 (1993); ibid. 49, 14 251 (1994)G. Kresse and J. Furthmüller, Comput. Mat. Sci. 6, 15 (1996)G. Kresse and J. Furthmüller, Phys. Rev. B 55, 11 169 (1996)
Static calculations, molecular dynamics, atomic Kinetic Monte Carlo
Cosires 2004 C.S. Becquart
The primary damage : MD simulations
Cosires 2004 C.S. Becquart
The primary damage
MD simulations 2i
2
ii t
rmf
Large systems ===> empirical potentials
Embedded Atom Method
Finnis Sinclair...
i
ii r
rf
V
M.W. Finnis and J.E. Sinclair, Phil. Mag. A 50 (1984) 45
R.J. Harrison, A.F. Voter and S.P. Chen, "Embedded Atom Potential for BCC Iron", Atomistic simulation
of Materials- Beyond Pair Potentials, V. Vitek and D.J. Srolovitz (editors), 219, Plenum New York (1989)
M.I. Haftel, T.D. Andreadis, J.V. Lill and J.M. Heridon, Phys. Rev. B 42 (1990) 11540
G. Simonelli, R. Pasianot and E.J. Savino, Mat. Res. Soc. Symp. Proc. 291 (1993) 567
R.A. Johnson and D.J. Oh. J. Mater. Res. 4 (1989)1195
Yu. N Osetsky and A. Serra, Phys. Rev. B 57 (1998) 755
Cosires 2004 C.S. Becquart
Fe I
•Not a T effect
•role of short range interaction of the potential
F
Fe II
RCS
Role of the cohesive model (interatomic potential)
Cosires 2004 C.S. Becquart
Use BCA adjusted on MD results
121212
62.13.022
1.055.035.0 a
r
a
r
a
r
eeer
eZrV 12a
r
eArV
Molière potential Born Mayer potential
range = distance between atoms for which V(r ) = 30 eV
)(rVh rstifness
Statistics needed:
Role of the cohesive model (interatomic potential)
Cosires 2004 C.S. Becquart
0
50
100
150
200
0.1 0.6 1.1 1.6
Molière IIIBorn Mayer III
Distance (Å)
Pot
entia
l Ene
r gy
(eV
)
0-200 eV : formation range of RCS
Role of the cohesive model (interatomic potential)
0 200 400 600 800 1000 1200 1400 16000
100
200
300
400
500
Effet du potentiel sur les LCSComparaison entre Molière et Born-Mayerajustés aux FeIII (Farkas)Sans DBND
Sans DBNDE=20 keV
Molière (a12
=0.0781) Born-Mayer (a
12=0.2180)
Mean n
um
ber
of
LC
S
Temperature (K)
No
mb
re m
oye
n d
e R
CS
Température (K)
Molière III
BM III
Mea
n nu
mbe
r of
RC
S
Temperature (K)
Cosires 2004 C.S. Becquart
Kin
etic
ene
rgy
(eV
)Role of the cohesive model
(interatomic potential)
0
10
20
30
40
50
0 1000 2000 3000 4000 5000 6000
Time (s)
Kin
eti
c e
ne
rgy
(e
V)
Time (x10-16s)
0
5
10
15
20
25
30
35
40
45
50
0 500 1000 1500 2000 2500 3000 3500
Time (s)
Kin
eti
c e
ne
rgy
(e
V)
Time (x10-16s)
Kin
etic
ene
rgy
(eV
)
MD Fe III potential. The sequence is defocusing, then focusing
MD Fe I potential. The sequence is defocusing
50 eV PKA initiated at 0.3 deg. from <111>
Influence of potential on focusing
Cosires 2004 C.S. Becquart
The stiffer the BCA potential (the shorter ranged)
•the lower the focalisation threshold•the less kinetic energy losses between successive collisions•the more numerous the RCS and the longer.
0.075 0.080 0.085 0.090 0.095 0.100 0.105 0.110 0.11510
20
30
40
50
60
70
80
90
100
AMLJ
Initial directions: <15, 15, 16> <15, 1, 1>
Seuil111 Seuil100
Focu
sin
g t
hre
sh
old
(e
V)
Screening length (Å)rayon d’écrantage (Å)
Seu
il de
foca
l isat
ion
(eV
)
Molière I
Molière III
Influence of potential on focusing
Role of the cohesive model (interatomic potential)
Cosires 2004 C.S. Becquart
The shorter the range for very high energies, the larger the cascade volume
Molière IIIBM III
Volume ao3
Fré
quen
cy
0
1000
2000
3000
4000
5000
0.1 0.6 1.1 1.6
Molière IIIBorn Mayer III
Distance (Å)
Pot
entia
l ene
rgy
(eV
)
The more diluted the cascade
Influence of potential on cascade expansion
Role of the cohesive model (interatomic potential)
Cosires 2004 C.S. Becquart
• Short potential range favours focusing in RCS
• Large potential range favours focusons on the expense of RCS
One third of the energy given by
PKA partitioned between replacement
sequences and focusons.
Role of the cohesive model (interatomic potential)
Cosires 2004 C.S. Becquart
• During the cascade development, one third of the energy given by the PKA to the lattice is partitioned between replacement sequences and focusons.
• Short potential range favours focusing and energy transport in RCS on the expense of focusons.
• The shorter the range for very high energies, the larger the cascade volume, the more “diluted” the cascade.
Main conclusions on the cohesive model
Quantitative results have to be taken with care
Better model for atomic interactions at small separations : ab initio calculations
M. I. Mendelev, S. Han, D. J. Srolovitz, G. J. Ackland, D. Y. Sun and M. Asta, Phil. Mag. A 83 (2004) 3977.
Threshold displacement energies not enough
Cosires 2004 C.S. Becquart
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1 2 3 4 5 6 7 8 9
cluster size (number of interstitials)
10 keV Fe III
10 keV Finnis type Fe [16]
5 keV Fe III
5 keV Finnis type Fe [16]
Cluster size (number of interstitials)
Cosires 2004 C.S. Becquart
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0 500 1000 1500 2000 2500
Fe I
Fe II
Fe III
Experimental
Temperature (K)
MS
D (
Å3 )
Temperature (K)
Latt
ice
para
met
er
(Å)
2.86
2.88
2.9
2.92
2.94
2.96
2.98
0 400 800 1200 1600 2000
Fe I
Fe II
Fe III
Experimental
Let’s not forget the thermal properties
Cosires 2004 C.S. Becquart
Evolution of the primary damage
Object Kinetic Monte Carlo
Cosires 2004 C.S. Becquart
Annihilation
Interstitial loop
Emission
Interstitial cluster
Vacancy cluster
traps
Vacancyloop
Electrons
Neutrons
Frenkel pairs
cascade
Object KMC: the events
+
Emission
Migration
Parameterisation
+
+
Recombination
•Gi =Gi0 exp( -Ea / kT)
>300nm
PBCor surface
sinks
Cosires 2004 C.S. Becquart
0
10
20
30
40
50
1E-12 1E-10 1E-08 1E-06 0.0001 0.01 1 100
Time (s)
Num
ber of
def
ects
All vacancies
Vacancy clusters
All interstitials
Interstitial clusters
OKMC ageing of 20 keV cascade in Fe 0.2%Cu
Absorbing boundary conditions
Cosires 2004 C.S. Becquart
Parameterisation : interaction with solute
atomsInterstitials
– No interaction with solute atoms
Vacancies
– V-Cu clusters: mobility decreases with size (# solute atoms and # V)
– V and (V-Cu) emission depends on binding and formation energies
diffusion / migration
V emission
V-Cu emission
Cosires 2004 C.S. Becquart
BABA rrd
loops
Reaction radii
V-I recombination distance
Exp 2.2 a0 - 3.3a0
MD 1.7 a0 - 1.9 a0
J. Dural, J. Ardonceau and J. C. Roussett, Le Journal de Physique 38 (1977) 1007‑1011.
M. Biget, R. Rizk, P. Vajda and A. Bessis, Solid state comm. 16 (1975) 949-952.
F. Gao, D. J. Bacon, A. V. Barashev and H. L. Heinisch, Mater. Res. Soc. Symp. Proc. 540 (1999) 703-708.
Cosires 2004 C.S. Becquart
Ab initio
EAM Ludwig et al.
4.05 Å
No recombination
FS Ackland et al.
Reaction radii
Cosires 2004 C.S. Becquart
Reaction radii
Highly anisotropic
Cosires 2004 C.S. Becquart
Reaction radii
Ageing of a 20 keV cascade
0
10
20
30
40
50
60
70
80
-14 -12 -10 -8 -6 -4 -2
r = 1 nn
r = 1.9 a0
r = 2.2 a0
r = 3.3 a0
Log(t) (s)
Me
an
nu
mb
er o
f de
f ect in
cluste
rs
1 st nn/2
1.9 a0/2
2.2a0/2
3.3a0/2
Cosires 2004 C.S. Becquart
0
1
2
3
4
5
-16 -12 -8 -4
Log(t) (s)
Me
an
nu
mb
er o
f V m
ixed
Cu
- V c lu
s ter s
0
0.5
1
1.5
2
2.5
3
-16 -11 -6
r = 1.25
r = 2.7
r = 3.2
r = 4.7
Log(t) (s)M
ea
n n
um
be
r of C
u in
mix e
d C
u-V
cluste
rs
Å
Å
Å
Å
Ageing of a 20 keV cascade containing 0.2 at.%Cu
Reaction radii
1 st nn/2
1.9 a0/2
2.2a0/2
3.3a0/2
Cosires 2004 C.S. Becquart
M. Eldrup, B.N. Singh, S.J. Zinkle, T.S. Byun and K. Farrell, Journ. Nucl. Mater. 307-311 (2002) 912-917] .
Neutron irradiation (HFIR flux)Density of vacancy clusters
Reaction radii
HFIR : dose-rate 10-6 dpa/s
dpa
Den
sity
(m
-3)
1E+23
1E+24
1E+25
0.0001 0.001 0.01 0.1 1
r = 1 nn/2
r = 1.9 a0/2
r = 3.3 a0/2
experimental
*
70°C
31016 FPcm‑3s‑1
41014 10 keV and 21014 20 keV cascade-debriscm‑3s‑1
Cosires 2004 C.S. Becquart
0
20
40
60
80
100
0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20
dpa
% C
u i
n p
rec
ipit
ate
s
Fe0.2at.%Cu, r = 1nn Fe0.1at.%Cu r = 1nn Fe0.2at.%Cu r = 1.9a0 Fe0.1at.%Cu 1.9a0 Fe0.2at.%Cu r = 3.3a0 Fe0.1at.%Cu r = 3.3a0 Experimental results
P. Auger, P. Pareige, S. Welzel, and J‑C. Van Duysen, J. Nucl. Mater. 280 (2000) 331.
% o
f C
u pr
ecip
itate
d
dpa
Neutron irradiation (HFIR flux)
% of Cu precipitated
Reaction radii
Fe0.2at.%Cu r = 1nn/2
Fe0.1at.%Cu r = 1nn/2
Fe0.2at.%Cu r = 1.9 a0/2
Fe0.1at.%Cu r = 1.9 a0/2
Fe0.2at.%Cu r = 3.3 a0/2
Fe0.1at.%Cu r = 3.3 a0/2
Experimental
Cosires 2004 C.S. Becquart
1E+22
1E+23
1E+24
1E+25
1E+26
1E+27
0.0001 0.001 0.01 0.1 1
Set A
set B, s = 0.51
set B, s = 10
set C
experimental
min
max
dpa
Den
sity
(m
-3)
M. Eldrup, B.N. Singh, S.J. Zinkle, T.S. Byun and K. Farrell, Journ. Nucl. Mater. 307-311 (2002) 912-917] .
Neutron irradiation (HFIR flux)
Density of vacancy clusters
Mobilities
dose-rate 10-6 dpa/s31016 FPcm‑3s‑1
41014 10 keV and 21014 20 keV cascade-debriscm‑3s‑1
Cosires 2004 C.S. Becquart
Mobilities
• INTERSTITIALS– mono–interstitials: 3D random walk– clusters: 3D random walk or 1D
along <111> direction (cf. MD)
I à 1000K
I à 600K 2 I à 600K
MD simulations
sm0clusters (size m >=2): attempt frequency
Em = 0.04 eV, s = 0.51
Yu. N. Osetsky, D. J. Bacon, A. Serra, B. N. Singh and S. I. Golubov, J. Nucl. Mater. 276 (2000) 65.
C.-C. Fu, F. Willaime, and P. Ordejón, Phys. Rev. Lett. 92, 175503 (2004)
Exp and Ab initio Em = 0.3 eV for SIA
Cosires 2004 C.S. Becquart
A. Hardouin du parc, Ph. D. Thesis, Paris XI-Orsay University (1997), ISSN 0429‑3460, CEA report R‑5791
Model experiment (A. Hardouin du parc, A. Barbu, CEA France)
1400 nm
1.5 10-4 dpa/s
900 s
TEM : interstitial dislocation loop density
Mobilities
Cosires 2004 C.S. Becquart
Mobilities
Set B, s = 10, large clusters almost immobile
Loop density after 1200 s
1.E+14
1.E+15
1.E+16
1.E+17
1.E+18
0.0015 0.0019 0.0023 0.0027 0.0031
1/T (K-1)
Loop
den
sity
(cm
-3)
*
set A
set B, r = 1nn/2
set B, r = 3.3 a0/2
experimental
s0 mclusters (size m >=2): attempt frequency
Em = 0.04 eV
Cosires 2004 C.S. Becquart
0.28 eV 0.36 eV 0.70 eV
Binding energies V-clusters 128 atoms,
3x3x3 kpoints
0
0.2
0.4
0.6
0.8
1
1.2
0 1 2 3 4 5 6
V cluster size (n)
Eb
(V(n
)-V
) (
eV
)
Ludwig et al.
Johnson & Oh
FS
ab initio (128 at.)
0.26 eV
0.36 eV
Cosires 2004 C.S. Becquart
Binding energies: larger clusters
Turn to empirical potentials
Need a clever way to find the most stable configuration
See D. Kulivov poster
050
100150
200250
300
50
100
150
200
0
20
40
60
80
100
120
140
Ef = 0.9 - 1.72*N
V
1/3 + 2.69*N
V
2/3 + 0.215*N
Cu
0.85 - N
Cu*0.0004*(N
V
1/3 + N
V
2/3)
Ef
N V
NCu
140120
10080
6040
20
0
10
20
30
40
50
0
10
20
3040
50
Ef (
eV
)
N V
NCu
Cosires 2004 C.S. Becquart
Main conclusions on the OKMC
•Very powerful technique to simulate many experimental situations:
•electron irradiation, neutron irradiation, annealing, isochronal annealing ...
•Combination of simulation techniques (AKMC, MD, MC, AB initio…) necessary
•Simple experiments necessary also
•Many unresolved questions, do we know enough physics?
Cosires 2004 C.S. Becquart
REVE VTR : a multiscale modelling of RPV vessel.
Very simple models, lots of parameters : need to use combined techniques, simpler as well as more
complicated ones.
Simple modelling oriented experiments very useful.
Need more physical insight (SIA loops).
REVE continues in the PERFECT project (6th FP Euratom).
CONCLUSIONS
Cosires 2004 C.S. Becquart
0
1
2
3
4
5
-16 -12 -8 -4
Log(t) (s)
Mean num
b er o f V m
i xe d Cu -V
clu st er s
Cosires 2004 C.S. Becquart
VIVVVVV cccDkKdt
dc 2
Vacancy production rate
Vacancy production rate
Vacancy-SIA recombination rate
Vacancy-SIA recombination rate
Disappearance of vacancies at sinksDisappearance of vacancies at sinks
Coupling with SIA concentration equation !
Coupling with SIA concentration equation !
Cosires 2004 C.S. Becquart
0
20
40
60
80
100
0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20
dpa
% C
u i
n p
rec
ipit
ate
s
Fe0.2at.%Cu, r = 1nn Fe0.1at.%Cu r = 1nn Fe0.2at.%Cu r = 1.9a0 Fe0.1at.%Cu 1.9a0 Fe0.2at.%Cu r = 3.3a0 Fe0.1at.%Cu r = 3.3a0 Experimental results
P. Auger, P. Pareige, S. Welzel, and J‑C. Van Duysen, J. Nucl. Mater. 280 (2000) 331.
% o
f Cu
pre
cip
i tate
d
dpa
Neutron irradiation (HFIR flux)
% of Cu precipitated
Reaction radii
Fe0.2at.%Cu r = 1nn
Fe0.1at.%Cu r = 1nn
Fe0.2at.%Cu r = 1.9 a0/2
Fe0.1at.%Cu r = 1.9 a0/2
Fe0.2at.%Cu r = 3.3 a0/2
Fe0.1at.%Cu r = 3.3 a0/2
Experimental
Cosires 2004 C.S. Becquart
Ab initio(pure Fe: 0.64 eV)
FS Ackland et al. (pure Fe: 0.77 eV)
EAM Ludwig et al.(pure Fe: 0.69 eV)
Mobilities
And what about clusters ?
J.R. Beeler Jr and R.A Johnson, Phys. Rev. 156 (1967) 677-684.
Mobility decreases with vacancy cluster size (size > 2)
Attempt frequency
Migration energy constant
1n112 )q(10.6
Cosires 2004 C.S. Becquart
Binding energies: Cun clusters
0.26 eV (128 at. 2x2x2 kpts2)
Most stable configurations 0.15 eV (128 at. 3x3x3 kpts)
-0.23 eV
-0.500.5
.
Eb (
eV
)
ab initio (54 at.)
ab initio (128 at.)
Eval (1nn & 2nn - ab initio 128 at.)
EAM (54 at.)
EAM (128 at.)
EAM (2000 at.)
Cu(n) clusters
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Cu–Cu (1nn) Cu–Cu (2nn) Cu–Cu (3nn) Cu2–Cu Cu3–Cu
Eb
(e
V)
Cosires 2004 C.S. Becquart
0.26 eV 0.17 eV0.28 eV
0.21 eV -0.03 eV 0.36 eV
Cu-Cu 1st nn - V 1nn
V 1st nn to both Cu atoms (no Cu interaction in 2nd nn)
128 atom cells calculations
Binding energies
Cosires 2004 C.S. Becquart
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 1 2 3 4 5 6
V cluster size (n)
Eb
(V(n
)-V
) (
eV
)EAM Ludwig et al.
Johnson & Oh,Soneda
FS Ackland, Bacon
Object KMC param,Wirth
ab initio (128 at.)
Cosires 2004 C.S. Becquart
w’3w2
w6
w
5
w4
w3
w’’3w’’4
w’4
)/66.2exp(2.2 kTeVDFeFe
)/44.2exp(2.2 kTeVDCuFe
cm2 s – 1
cm2 s – 1
9-frequency model (Le Claire)
nFe = nCu = 3.65 10 15s-1
Hypothesis
[1] A.D. Le Claire, in Physical Chemistry: an advanced treatise, edited by H. Eyring, Academic Press, New York, 1970), vol. 10, chap. 5.
[1]
[2]
CuFe
FeFe DD
[2] F. Soisson, G. Martin and A. Barbu, Annales de Physique, vol.20 (1995) C3-13.
Cosires 2004 C.S. Becquart
Influence of potential on vacancy-interstitial separation distances
Frenkel Pair separation distancedistributions.
The frequencies are the largestwhen the energy carried by RCS is the largest and energy carried byfocusons is the smallest
0 1 2 3 4 5 6 7 8
0
100
200
300
400
500
600Statistics over 1000 cascadesE
PKA = 20 keV
T = 0 K
Freq
uenc
y
Vacancy-Intersitial Pair separation distance (lu)
MolièreI MoliereII MolièreIII
freq
uenc
y
Vacancy-interstitial pair separation distance (a0)
Role of the cohesive model (interatomic potential)
Cosires 2004 C.S. Becquart
Fuel. Usually pellets of uranium oxide (UO2) arranged in tubes to form fuel rods. The rods are arranged into fuel assemblies in the reactor core.
Moderator. This is material which slows down the neutrons released from fission so that they cause more fission. It may be water, heavy water, or graphite.
Control rods. These are made with neutron-absorbing material such as cadmium, hafnium or boron, and are inserted or withdrawn from the core to control the rate of reaction, or to halt it. (Secondary shutdown systems involve adding other neutron absorbers, usually as a fluid, to the system.)
Coolant. A liquid or gas circulating through the core so as to transfer the heat from it.
Pressure vessel or pressure tubes. Either a robust steel vessel containing the reactor core and moderator, or a series of tubes holding the fuel and conveying the coolant through the moderator.
Steam generator. Part of the cooling system where the heat from the reactor is used to make steam for the turbine.
Containment. The structure around the reactor core which is designed to protect it from outside intrusion and to protect those outside from the effects of radiation or any malfunction inside.Ý It is typically a metre-thick concrete and steel structure.
There are several different types of reactors as indicated in the following table.
Cosires 2004 C.S. Becquart
guide design and analysis of experimental irradiation programs
explore conditions outside existing databases (very long time and high fluences), important to lifetime extension
systematically evaluate individual and combined influence of multitude of material variables (composition and microstructure) and the irradiation service conditions (T, flux, spectrum, ...)
help design advanced materials for future fission and fusion reactors.
Virtual Test Reactors (VTRs)
Cosires 2004 C.S. Becquart
Reconstruction 3D acier VVER 440 irradié neutrons (20 ans)
Volume de 1515 50 nm3 (serie1)Cu
PSi
FeNiNi
Mn
Courtesy: Philippe Pareige
Cosires 2004 C.S. Becquart
Volume de 1515 50 nm3 (série 2) Cu
+
P Si
FeNi Ni
Mn
Cosires 2004 C.S. Becquart
Zoom sur un des amas 555 nm3Cu
+
P Si
FeNi Ni Mn