Role of Accelerators in Studying Radiation Damage in Nuclear Structural Materials

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Role of Accelerators in Studying Radiation Damage
in Nuclear Structural Materials
P. Mukherjee, P. Barat, S. K. Bandyopadhyay, N.
Gayathri, M. Bhattacharya
Variable Energy Cyclotron Centre Kolkata
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Importance of radiation damage in context with
core structural Materials
To encase the fuel in fuel tubes
Core Structural Materials
To hold fuel tubes together in fuel assemblies
To hold fuel assemblies in place
Core structural materials suffer from intense
radiation damage
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Structural integrity of core structural material
is very important
To achieve higher burn up
The effective time that fuel remains in the
reactor core and the amount of energy it releases
Lower fuel cost
Less waste for ultimate disposal
Lower spent fuel storage cost
There is a continuous historical increase in the
fuel burn up !!
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Radiation damage suffered by structural materials
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Microscopic and sub-microscopic effect on
structural materials
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• Macroscopic Effects on Structural Materials
• Degradation of mechanical properties
• Irradiation embrittlement
• Radiation induced growth and swelling
• Irradiation creep
• Phase transformation
• Segregation of alloying elements

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High burn up of fuel
Service performance of core structural materials
Maintain integrity of fuel rods and fuel
assemblies
Preventing release of radioactive material
Need of development of radiation resistant
reactor core structural material
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Ion irradiation plays a very important role in
studying radiation damage in materials

• short irradiation time
• minimum residual radioactivity
• effective for studying fundamental effects of
  irradiation on materials

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• Difference in damage process
• Nature of displacement cascade
• Rate of damage accumulation (displacement rate
  is increased by 102 to 103 order)

The ideal simulation of neutron irradiation with
ions would require the same recoil spectra.
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Emulation of neutron irradiation effects with
ions validation with models
Controlling irradiation condition to arrive at a
nearly identical microstructure and microchemistry
Time scales of the atomic displacement cascade
development
Phase Characteristic time Collision
stage 0.1ps Relaxation stage lt
1ps Cooling/recombination stage lt
10ps Diffusion of freely migrating defects
10-1 -106 s
Control on the kinetics of defects is very
important
Irradiation Temperature
Total dose
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Reactors used for radiation damage studies

• Five operational Fast flux reactors
• PHENIX (France)
• JOYO (Japan)
• FBTR (India)
• BOR-60, BN-60 (Russian Federation)

Shortage of experimental test facilities

• International Fusion Materials Irradiation
• Facility (IFMIF) in ITALY using 14 MeV neutrons

Ion irradiation plays an important role !!
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Accelerators used for Radiation damage
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Our achievements in studying radiation damage
using ion beams till date

• Irradiation has been carried out using
• Proton beam from VEC and IOP
• Oxygen beam from VEC
• Neon beam from VEC

• Studies have been carried out on irradiated
  materials (zirconium based alloys, stainless
  steel, D9, Ti and its alloys)
• Microstructural aspects (point defects,
  dislocation, stacking faults etc)
• Degradation of mechanical properties with
  irradiation

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Effect of Neon Irradiation on Zirconium Alloy
Sample Zr-1.0Nb-1.0Sn-0.1Fe (Zirlo) Beam
145 MeV Ne6

• A. Sarkar et.al., Met. and Mat. Transaction A,
  in press
• A. Sarkar et.al., Journal of Nuclear Materials,
  372, 285-292 (2008)

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X-ray diffraction profiles
Average Domain Size, Average Microstrain and
Average Dislocation Density with irradiation dose
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Electron density distribution on (0001) at z0.25
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Effect of Oxygen Irradiation on Titanium Alloy
Sample Titanium and Ti-5Ta-2Nb Beam 116 MeV
O5

• P. Mukherjee et.al., Met. and Mat. Transaction
  A, 36A, 2351-2360 (2005)

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Shape of the Domain
(a)
(b)
Projection of surface weighted domain size on the
plane containing directions lt002gt and lt100gt
(First quadrant) for (a) unirradiated and
irradiated Titanium and (b) unirradiated and
irradiated Ti-5Ta-2Nb.
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Effect of Oxygen and Proton Irradiation on
Zirconium Alloy
Sample Zr-1.0Nb-1.0Sn-0.1Fe (Zirlo) Beam
116 MeV O5 and 15 MeV proton

• P. Mukherjee et.al., Materials Characterisation,
  55, 412-417 (2005)
• P. Mukherjee et.al., Journal of Nuclear
  Materials, 305, 169-174 (2002)
• P. Mukherjee et.al., i.b.i.d., 297, 341-344
  (2001)
• P. Mukherjee et.al., i.b.i.d., 273, 338-342
  (1999)

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Mechanical Properties
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Effect of Neon irradiation on Stainless Steel
Sample SS 316L Beam 145 MeV Ne6

• P. Mukherjee et.al., (communicated)

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Variation of average domain size, average
microstrain with irradiation dose from modified
Rietveld method
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Future Plans
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Ion Irradiation
High current Proton irradiation (DAE
Medical Cyclotron)
Low current Proton irradiation (VEC)
Heavy Ion Irradiation (SCC)
Zirconium based alloys For PHWR
Nuclear Structural Materials
Stainless steels (SS316, D9, D9I) For PFBR
Ferritic steels (9Cr-1Mo) For ADSS
Fusion Reactor Materials
Mechanical properties
Thermophysical properties
Microstructural effects
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• Radiation Damage Studies Using Superconducting
  Cyclotron
• Bulk penetration
• High dpa
• Comparison with the damage created by Fission
  fragments

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THE DAE MEDICAL CYCLOTRON
Beam Current 350?A(500?A) Energy 15-30 MeV
Damage Production

• ? Microstructural Characterisation
• ? ? Mechanical Properties
• ? ? Phase Stability Under Irradiation (In
  Advanced Austenitic Steels and ODS)
• ? ? ? High dpa irradiations for the Development
  of Void Swelling Resistant Steels
• ? ? ? Ductile to Brittle Transition in Ferritic
  Steels

Front line Research and applications with impact
on the economic operation of fast reactors and
development of materials for fusion reactors
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All dimensions are in mm
Target flange will carry a weight of 25 kg
distributed load
? 1000 mm
? 300
100 mm
750
j 100 mm
Port for vacuum to match Gate valve
100 mm
350mm
100 mm
1250 mm
400 mm
Turbo pump
Ground level
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Electrical feed through port
Helium pumping port
Port for Solid state laser for aligning sample
Port for Copper cooling pipes for beam dump
Inner flange with sample and cooling arrangement
Graphite Beam dump
Port of Lamp
Beam port connected to beam line
Sample
450
IR pyrometer port
Port dimension 200 mm diameter To facilitate
removal of Beam dump
RR camera view port
Cross sectional view of the median plane
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Cooling arrangement for Thin samples Inclined
Helium slots

• Helium Jet cooling arrangement
• Helium gas at 30oC
• Up to 500W heat removal on 20x20x0.4 mm3
  samples.
• Helium Jet velocity 200 m/sec at the slot.
• Maximum sample temperature 600 oC
• Coolant temperature rise 13oC

Proton beam penetrates the sample
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For Thick samples water cooling arrangement

• Conceptual achieve high cooling powers 6KW
• Difficulty in decreasing the contact resistance
  between the sample and the coolant tube.
• Sn or In being considered.
• Liquid
• Activity

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• Major equipments which will be purchased to carry
  out the following studies
• Characterisation of Microstructure /
  Micro-texture
• Scanning Electron Microscope with EDAX/ EBSD/
  WDS
• Determination of Mechanical properties of
  Irradiated alloys
• High temperature attachment with existing
  universal Testing machine
• Automated Ball indentation measurement
• Determination of thermophysical properties
• Thermal conductivity set up

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T H A N K Y O U