Fabrication of Metallic Fuel Slugs for
Irradiation Experiments in Fast
Breeder Test Reactor
M.T. Saify, S.K. Jha, K.K. Abdulla, Arun Kumar and G.J. Prasad
Bhabha Atomic Research Centre
INDIA
International Conference on Fast Reactors and Related Fuel Cycles: Safe Technologies and Sustainable Scenarios
Paris, France - 4 to 7 March 2013
3/13/2013
1
Advantages of Metallic fuels for future FBR
High heavy metal atom density
Higher thermal conductivity at room temperature that
increases with temperature
Metal fuels can be relatively easily fabricated with close
dimensional tolerances
They have excellent compatibility with liquid metal
coolants
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2
Issues of metallic fuel
Dimensional stability under irradiation
Solidus temperature of the fuel
Chemical compatibility with cladding
Swelling and fission gas release
These issues have been addressed by addition of
several alloying elements to U or U-Pu fuels out of
which ‘Zr’ was found to be the most promising.
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3
Design Challenges in Metallic Fuel
DESIGN CHALLENGES
MITIGATION
Eutectic formation between
U and SS cladding (Fe)
• Zr liner between fuel and
clad
• Zr added in the fuel
Low melting / solidus temp.
Zr added to fuel
High Swelling
Low smeared density
(~75%TD)
Preferential axial swelling
Higher plenum volume
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4
METALLIC FUEL – INDIAN DESIGNS
Sodium Bonded Fuel Pin
Mechanically Bonded Fuel
T91 CLAD
4.90 Ø
U19%Pu6%Zr
5.40 Ø
Zr LINER
SODIUM
U-15%Pu
FUEL
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5
FABRICATION FLOW-SHEET FOR SODIUM BONDED
METALLIC FUEL
Preparation of Alloy
Injection Casting
Loading Sodium into one–end
closed Clad Tube
Loading Fuel Slug & Blanket into
pre-filled Clad Tube
De-moulding
Pin Welding
End-shearing
Sodium Bonding
Length, Weight, Dia. Measurement
& ECT
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Pin Qualification by NDT
Wire Wrapping & Final Metrology6
Metallic Fuel Specifications
Specifications establishing technical requirements of binary metallic fuel
slugs for irradiation experiments in FBTR
Fuel
Zr-content, (wt.%)
Mass, g
Length, mm
Diameter, mm
Linear Mass, g/cm
Straightness
Surface Roughness, Ra, (µm)
ECT
3/13/2013
Specifications
Enriched U-Zr alloy
6.0 (+1 / -0)
51.7 (+2.4 / -3.2)
160 ± 2
4.90 ± 0.06
3.23 (+0.11 / -0.16)
0.2/160
3.2
Max. acceptable total sub-surface defect in any
cross- section shall be 1% area of the slug
7
WHY U-Zr ALLOY ?
Technology development – U-Zr alloy to simulate FUEL
Important sub-system of U-Pu-Zr ternary alloy
Proposed as blanket material
KEY ISSUES “U-Zr ALLOY PREPARATION”
• Large difference in melting point
• Large difference in density
• Higher reactivity of Zr with graphite (Carbon)
• Oxidation of uranium hindering alloying by diffusion
Mitigation Approach to preparation of U-Zr alloy
1.
2.
3.
4.
Careful charge preparation
Appropriate charging sequencing
Tripple melting in specially designed graphite crucibles
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Better performance ceramic coating on crucible
8
INJECTION CASTING - BASIS
Elementary physical concept – the possibility of supporting a liquid column within a
tube, by the application of a pressure difference
across the liquid interface inside and outside the tube.
FEATURES
Possible to produce small diameter castings
of high L/D ratio with randomly oriented
grain structure
Possibility of multi-mould casting –
limited only by criticality considerations
and handling facilities
Capability of producing precision
castings
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INJECTION CASTING SET-UP FOR FEASIBILITY
STUDIES AT BARC
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10
INJECTION CASTING
SET-UP
MOULD MOVEMENT
SYSTEM
BELL CHAMBER
QUARTZ MOULDS
BOTTOM CHAMBER
Control Panel
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Dec.1-2,
2008
IAEA TM, Fukui
11
QUARTZ MOULD PREPARATION
Alumina Coated
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Yttria Coated
Mould End Closure
Defect
12
MECHANIZED SYSTEM FOR QUARTZ
MOULD ID COATING
Moulds Filled Upto
70% of Specified
Height
Moulds Filled Upto
Specified Height
Features
1. Capacity : 40 tubes at a time
2. Control
3/13/2013 of Coating Height
13
INJECTION CASTING SET-UP...FEATURES
Graphite Crucible Size
125mm IDx160mm ODx160mm H
Capacity
20 kg Uranium
Induction Power Supply
30 kW, 400V, 5 kHz, IGBT based
Metal & Alloys Injection Cast
Pure Uranium, U-1%Zr, U-2%Zr,
U-6%Zr and U-10% Zr alloy
14
INJECTION CASTING SET-UP INSTALLED IN
GLOVE BOX
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CRUCIBLE LOADING UNLOADING SET-UP
Features
1. Capacity : 30 kg
2. Capable of remote operation from
outside the Glove Box
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MOTORISED MOULD LOADING AND
UNLOADING SYSTEM
Mould Cassette
Holder
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17
Injection Cast ‘U’rods (single batch; max. capacity 40 fuel rods)
Injection casting of
U rods
In Quartz Mould
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After removal of mold
18
DEMOULDING AND SHEARING UNIT IN GLOVE BOX
Loading Tray
HSS Blade
Cr-Plated, Hardened & Ground Rollers
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Fuel Rod Collection Tray
19
DEMOULDED AND SHEARED U-Zr RODS
SHEARED RODS
BURR-FREE SHEARED ENDS
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20
AUTOMATED INSPECTION SET-UP
Weight
: Static Load cell
(100 to 1000 g ±0.1 gm)
Length
: Linear Variable Differential Transformer (LVDT)
(320 ± 1.0 mm)
Diameter
: Linear Variable Differential Transformer (LVDT)
(5.45 ± 0.02 mm with suitable coil)
(4.37 ± 0.02 mm with suitable coil)
ECT
: Coil - Differential Encircling
Frequency - 100 kHz
Std. Depth of Penetration
Effective Depth of Penetration
Defect Standard
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- 1.0 mm
- 2.5 mm
- 0.5 mm Ø x 0.2 mm deep
21
AUTOMATED INSPECTION SET-UP
Accepted/Rejected Rod
Collection Station
ECT COIL
LVDT for Dia.
Measurement
LVDT for Length
Measurement
Fuel Rod Loading
Station
Load Cell for Weight
Measurement
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EDDY CURRENT TEST RESULT
Coil: Differential
Frequency: 200 kHz
BOTTOM
TOP
5 nos. of flat bottom holes showing 5 ECT
Signal in the bottom part (vertical
component of ECT Signal) of the chart
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No ECT signal having amplitude more than the
reference signal as shown in the bottom part
(vertical component of ECT Signal) of the
chart
23
METALLIC FUEL FABRICATION AND INSPECTION FACILITY
DEMOULDING &
SHEARING SET-UP
AUTOMATED
INSPECTION SETUP
INJECTION CASTING
SET-UP
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SWAGING
24
MACHINE
RESULTS AND DISCUSSION
A. First melt for homogenous U-Zr alloy – 0.75wt% extra zirconium
Slag Phase
Oxidation Loses
B. Specified surface finish
X Water based Ceramic Coating
Alcohol based Graphite Coating
C.
Specified as-cast diameter is obtained using quartz moulds having
180 µm higher ID
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25
Thank
You…
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26
HIGH ENERGY GAMMA RADIOGRAPHY OF INJECTION CAST URANIUM AND U-Zr
ALLOY SLUGS
8mm diameter (Zr clad)
6 mm diameter
Radiograph of cast metallic
uranium fuel slugs
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Source : Co-60 (7.5 Curie)
27
Specifications of Metallic Fuel Slugs for Irradiation Experiments in FBTR
Fuel
Zr-content
(wt.%)
Sodium Bonded
Mechanically Bonded
Enriched U-Zr alloy
Enriched Uranium
6.0
(+1 / -0)
-
51.7
(+2.4 / -3.2)
160 ± 2
4.90 ± 0.06
3.23
(+0.11 / -0.16)
160 ± 2
5.40 ± 0.05
Groove Radius, mm
-
1.06 ± 0.1
Number of grooves
NIL
2
(Diametrically opposite)
0.2/160
0.2/160
3.2
1.6
Mass, g
Length, mm
Diameter, mm
Linear Mass, g/cm
Straightness
Surface Roughness, Ra, (µm)
ECT
3/13/2013
58.9 ± 4.2
Max. acceptable total sub-surface defects in any crosssection shall be 1% area of the slug
28
FBTR FUEL SPECIFICATIONS – MK I & MK II
Specification
Chemical
Physical
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(Pu0.7U0.3)C
(Pu0.55U0.45)C
Pu (wt %)
66±1
51.9±1
Pu + U (wt %)
≥ 94
≥ 94
Am (wt %)
Not Specified
0.3 Max.
O2 (ppm)
≤ 6000
≤ 5000
O2 + N2 (ppm)
≤ 7500
≤ 6000
M2C3 (wt %)
5 - 20
5 -15
W (ppm)
≤ 200
≤ 200
Total Impurities (ppm)
(excluding O2 , N2 & Am)
≤ 3000
≤ 3000
Diameter (mm)
4.18±0.04
4.18±0.05
Height (mm)
7.00±0.04
7.00±0.05
Density (%TD)
90±1
90±1
1.67±0.04
1.60±0.04
Linear Mass (g/cm)
29
PFBR FUEL SPECIFICATIONS
Parameter
Chemical
Pu (wt %)
18.7 / 24.4
U (wt %)
69.9 / 63.7
O/M
1.99±0.01
Total Impurities (ppm)
Diameter (mm)
Height (mm)
Physical
3/13/2013
≤ 5000
5.58±0.04
8±2
Linear Mass (g/cm)
2.18±0.07
Pellet Inner Diameter (mm)
1.90±0.2
Fuel Stack Length (mm)
Metallurgical
Specification
1000.0±2.5
Grain Size (µm)
5 - 50
Micro-homogeneity
PuO2 Particle Size (µm)
< 100
30
Average number of Neutrons Liberated in Fission
Thermal Neutrons
(0.0253 eV)
Fissile Nucleus
η
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Fast Neutrons
(~1 MeV)
η
U-233
2.29
2.40
U-235
2.07
2.35
Pu-239
2.15
2.90
31
Allotropic phase transformation in Uranium
Phase
Stability
Structure
Lattice Parameter
α - Uranium
-231 oC to 667.3 oC
Orthorhombic
a=2.8536 Å
b=5.8698 Å
c=4.9555 Å
β - Uranium
667.3 oC to 774.8 oC
Tetragonal
a=10.52 Å
c=5.57 Å
γ - Uranium
774.8 oC to 1132.3 oC
Body-centered
cubic
a=3.49 Å at 800 oC
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COMPOSITION OF D9 AND T91
Chemical composition of Stainless Steel Clad in wt%
3/13/2013
Element
D9
T91
Ni
15.5
0.5
Cr
13.5
12.0
Mn
2.0
0.2
Mo
2.0
1.0
Si
0.75
0.25
Ti
0.25
-
W
-
0.5
V
-
0.5
C
0.04
0.2
Fe
Balance
Balance
33
FAST REACTOR FUEL IN 1950s & 1960s : TYPES & COMPOSITIONS
Fuel Type
Metal
3/13/2013
Composition
Reactor
Year
Country
Pu
Clementine
1949
USA
U
EBR-I Mk I
1951
USA
U-Zr
EBR-I Mk II
1954
USA
U-Zr
EBR-I Mk III
1957
USA
Pu-Al
EBR-I Mk IV
1962
USA
Molten Pu-Fe
LAMPRE-I
1959
USA
Molten Pu-Fe
LAMPRE-II
1962
USA
U-Cr
DFR Mk II
1963
UK
U-Mo
DFR Mk IIA,B,C
1963
UK
U-Mo
DFR Mk IIIA,B,C
1964
UK
U-Fs
EBR-II Mk I, IA
1964
USA
U-Fs
EBR-II Mk II
1973
USA
U-Mo
Fermi
1966
USA
34
FAST REACTOR FUEL IN 1970s & LATER : TYPES & COMPOSITIONS
Fuel Type
Ceramic
3/13/2013
Composition
Reactor
Year
Country
(U,Pu)O2
Phenix
1974
USA
(U,Pu)O2
PFR
1974
USA
(U,Pu)O2
EBRKNK-II
1977
USA
(U,Pu)O2
FFTF
1980
USA
(U,Pu)O2
JOYO
1980
USA
(U,Pu)O2
BN600
1980
Russia
(U,Pu)O2
Superphenix
1986
(U,Pu)N
BR-10
-
Russia
(U,Pu)C
FBTR
1985
India
(U,Pu)O2
Monju
1992
Japan
(U,Pu)O2
EFR
*
Europe
(U,Pu)O2
BN-800
*
Russia
(U,Pu)O2
DFBR
*
Japan
(U,Pu)O2
PFBR
*
India
(U,Pu)O2
CEBR
*
China
35
FAST REACTOR FUEL IN 1970s & LATER : TYPES & COMPOSITIONS
Fuel Type
Ceramic
3/13/2013
Composition
Reactor
Year
Country
(U,Pu)O2
Phenix
1974
USA
(U,Pu)O2
PFR
1974
USA
(U,Pu)O2
EBRKNK-II
1977
USA
(U,Pu)O2
FFTF
1980
USA
(U,Pu)O2
JOYO
1980
USA
(U,Pu)O2
BN600
1980
Russia
(U,Pu)O2
Superphenix
1986
(U,Pu)N
BR-10
-
Russia
(U,Pu)C
FBTR
1985
India
(U,Pu)O2
Monju
1992
Japan
(U,Pu)O2
EFR
*
Europe
(U,Pu)O2
BN-800
*
Russia
(U,Pu)O2
DFBR
*
Japan
(U,Pu)O2
PFBR
*
India
(U,Pu)O2
CEBR
*
China
36
FAST REACTOR FUEL IN 1970s & LATER : TYPES & COMPOSITIONS
Fuel Type
Metallic
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Composition
Reactor
Year
Country
U-Zr
EBR-II MK III, IV
1990
USA
U-Pu-Zr
EBR-II MK V
1995
USA
U-Pu-Zr
IFR
-
USA
U-Pu-Zr
PRISM
-
USA
37