Download 1-04 - Jack Haley - Proton irradiation

Simulating fusion neutron damage
using protons in ODS steels
Jack Haley
1. Fusion Power and radiation damage
2. Simulating neutron damage
3. Simulating with protons
4. Project plan
Fusion Power
• Deuterium and Tritium fuse to produce a
3.5MeV alpha particle and 14.1MeV neutron
+
+
+ +
Fusion Power
• Neutrons cause hardening, embrittlement and swelling in components.
• Enormous demands placed on the structural steels
• ODS steels are excellent at handling the radiation
• ODS precipitates pin dislocations and act as sinks for defects and
Helium [1]
+
[1] Brodrick, J., Hepburn, D. J., & Ackland, G. J. (2014). Mechanism for radiation
damage resistance in yttrium oxide dispersion strengthened steels. Journal of
Nuclear Materials, 445(1-3), 291–297. doi:10.1016/j.jnucmat.2013.10.045
+
+ +
Simulating the neutrons
• Closest thing to fusion neutrons available fission neutrons
Lower energy (~2MeV)
Takes a long time
Makes samples radioactive
• Self ion irradiation is widely used
High dose rate
Many facilities available, eg JANNUS, MIAMI
Multi beam energies
In situ with TEM, Helium implantation
• Self ions irradiation behave like the primary knock on atom in neutron irradiation
Fission neutron PKA up to 200keV
Fusion neutron PKA up to 1MeV [2]
[2] Dierckx, R. (1987). The importance of the pka-energy for damage simulation
spectrum. Journal of Nuclear Materials, 144, 214–227.
Simulating with self-ions
Dose
SRIM damage calculation as a function of depth in Fe
2.9MeV Fe ions @ 2.2nA
-0.10
0.10
0.30
0.50
0.70
0.90
Depth (μm)
1.10
1.30
1.50
Simulating with self-ions
[3] Taken from Chris Hardie’s Dphil thesis, 2012
Oxford University
Simulating with self-ions
Size effect in micromechanical testing
• As sample size decreases, yield strength increases
Fe-6Cr
[3]
[3] Taken from Chris Hardie’s Dphil thesis, 2012
Oxford University
Simulating with protons
Dose
SRIM damage calculation as a function of depth in Fe
2.9MeV protons @ 100μA
Smooth Damage
Region
0.00
5.00
10.00
15.00
20.00
25.00
Depth (μm)
30.00
35.00
40.00
Simulating with protons
• Higher dose rate than neutrons, but much lower than heavy ions – need
higher currents
• Very different recoil energy (PKA <0.5keV) than fusion neutrons
Simulating with protons
• Dominant energy loss mechanism of proton is by ionization
• May be a problem with ODS steels – oxide precipitates could be degraded due
to the ionization
Energy
(eV/Ang/Ion)
Loss (eV/Ang/ion)
Energyloss
Energy Loss
Loss of
of 2.9MeV
2.9MeV protons
Fe ions in
Energy
inFe
Fe
1.0E+02
1.0E+02
EnergyLoss
LossbybyIonization
Ionization
Energy
EnergyLoss
LossbybyPhonons
Phonons
Energy
1.0E+00
1.0E+00
1.0E-02
1.0E-02
1.0E-04
1.0E-04
1.0E-06
1.0E-06
0.00E+00
0.0E+00
1.00E+05
5.0E+03
2.00E+05 1.0E+04
3.00E+05
Depth
Depth(Ang)
(Ang)
4.00E+05
1.5E+04
Protons in the literature
• Gary Was et al – Emulation of neutron irradiation effects with protons:
Validation of principle [4]
2002 paper studied:




Radiation Induced Segregation
Microstructure (dislocation loops)
Irradiation hardening
Susceptibility to IASCC
Found excellent agreement between fission neutrons irradiated at 275oC
and 3.2MeV protons at 360oC
• Higher temperature proton irradiation balances the increased displacement
rate by enhancing diffusion kinetics.
[4] Was, G. S. et. Al. (2002). Emulation of neutron irradiation effects with
protons : validation of principle, 300, 198–216.
Simulating with protons
• Still no proton studies on martensitic FeCr and ODS steel
• Recoil energy influence on the radiation induced damage is dependent on
 Composition
 Irradiation temperature
 Lattice structure
• There is no magic formula (yet!) for determining appropriate proton irradiation
conditions to reliably mimic neutron damage
Simulating with protons
• University of Birmingham has two particle accelerators available for proton
irradiation of materials
Accelerator facilities are housed in
 Cyclotron
the Medical
Physics
Buildingset up
1-9MeV protons
– 2.9MeV
preferred
~10μA beam current
to 2cm diameter beam size
at the up
University
Capable of ~10-6 dpa/s in Iron which translates as ~0.05 dpa/day
Temperature control up to 600oC available now
 Dynamitron
1-3MeV protons
100s of μA beam current easily possible, absolute maximum 2mA
Up to 2cm diameter beam size
~10-5 - 10-4 dpa/s
~1 dpa/day at 100 μA
Temperature control in the works
Image Copyright Phil Champion. This work is licensed under the Creative Commons Attribution-Share Alike 2.0 Generic Licence. To
view a copy of this licence, visit http://creativecommons.org/licenses/by-sa/2.0/ or send a letter to Creative Commons, 171 Second
Street, Suite 300, San Francisco, California, 94105, USA.
Project plan
Key questions:
• How is the microstructural damage produced by proton, heavy
ion and fission neutrons different?
• What are the differences in mechanical properties?
• Is the proton damage representative of neutron damage under
any irradiation conditions?
Project plan
Next Steps
• Start work initially on FeCr binary alloys 0-15% Cr content
• ODS steels later
• Heavy ion irradiation at JANNUS in May
• Use Cyclotron in the summer for first proton irradiations, up to
0.6dpa to match neutron specimens at CCFE at same temperature
• Once Dynamitron is ready, use to irradiate at higher doses
Project plan
• Characterise the microstructural damage using TEM and relate this with
micromechanical tests

Dislocation loops

Hardening using nano-indentation and micro-cantilevers

Atom probe tomography?
• Dose and dose rate dependance
• Irradiation temperature dependence
• Composition dependence