powder-metallurgy experiments and manufacturing studies on
TRANSCRIPT
10th International Conference on Environmental Remediation and Radioactive Waste Management
Session: 45: Beneficial Uses of Depleted UraniumGlasgow, Scotland; September 7, 2005
Oak Ridge National LaboratoryP.O. Box 2008, Oak Ridge, Tennessee 37831-6165
United States of AmericaE-mail: [email protected]
Powder-Metallurgy Experiments and Manufacturing Studies on DUO2─Steel Cermets for SNF
CasksCharles W. Forsberg
Terry N. TiegsVinod K. Sikka
*Managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725. The submitted manuscript has been authored by a contractor of the U.S. Government under contract DE-AC05-00OR22725. Accordingly, the U.S. Government retains a nonexclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U.S. Government purposes. File name: ICEM05.Cermet
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Outline
• Cermet Cask Description
• Manufacturing Options
• Laboratory Tests
• Conclusions
GNS Storage and Transport Cask
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Cermets Combine the Best Properties of Ceramics (Shielding, Hardness, etc.)
and Metals (Strength, Ductility, etc.)
04-070
Main Battle Tank Armor
Cutting Tools
Brake Shoes
Cask Body
Clean Steel
Metal Matrix
Ceramics
- Strength- Thermal
Conductivity
- Armor (Al2O3, SiC)
- Neutron Shielding (DUO2, Gd2O3)
- Gamma Shielding (DUO2)
Cermets Are Used for
Demanding Applications
Cermet Body Cross Section
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Cermet Casks will be Adopted if Manufacturing Costs are Low
• Two manufacturing options are being examined in the United States− Forged Cermet Cylinder (FCC) Process− Cermet Extrusion Section (CES) Process
• Both processes use powder metallurgy techniques
• Manufacturing studies are underway to understand the economics
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Forged Cermet Cylinder Process(United States Patent: 6,811,745: November 2, 2004)
02-090R3
Add Steel/DUOParticulate Fill
to AnnularPreform
2
Seal Preformand Degas
HeatPreform
Steel/DUO2Particulate Fill
Steel Shells
Future CaskLid Mating
Surface
Powder Mix
Weld andVacuumDegas
Consolidate Particulates to Cermet
Forge or Roll
Weld Bottomonto Package(Steel-to-Steel Weld)
Machine Cask LidMating Surfaces
DriveRoller
IdleRoller
CermetPreform
AxialRollers
Anvil
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Step 1: Manufacture of Cask Preform
03-105
• Preform dimensions are slightly larger than the final cask
• Preform becomes the final inner and outer surfaces of the cask• Wall thickness: 1–3 cm• Flange
• Thickness: 10–20 cm• Face for lid
Future Top Flange
Outer Surface ofFinal CaskInner Surface
Void
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Step 2: Empty Preform is Mounted Upside Down on Turntable and Filled
with Cermet Particulate Mixture
02-119R
Feed System
Preform
Advanced OptionIntegrated Cermet
Cask Bottom
Different CermetParticle Mixes
ParticulateMix
Future TopFlange
InsideBottomof Cask
ParticulateFill Line
RotatingPlatform
TampingArm
HydraulicLift
MaterialsFeeder
Cask Preform(Near FinalDimensions)
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Step 3: Loaded Preform is Sealed and Degassed
03-107
• Weld annular ring to seal preform
• Degas− Heat− Vacuum
• Send sealed package to forging operations
Future Top Flange
Outer Surface ofFinal Cask
Inner Surface
Particle Mix
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Step 4: Cermet Consolidation by Hot Forging (Several Forging Options)
02-116
Anvil
CermetPreform
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Step 5: Cask Finishing Operations
03-104
• All finishing operations involve steel preform (No contact with cermet)
• Cask bottom is welded to the cask body− Option for integrated
cask bottom− Option requires
complex forging operation
• Cask machining− Machine lid surface and
bolt holes− Cask surfaces
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
CES Production Process (Assembly)
• Cask consists of:− External steel shell− Internal steel shell− Cermet sections
• Cermet sections have a steel exterior and a cermet interior
• Considering 12 to 48 cermet sections per cask
Cermet
CaskOuter layer
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Modern Extrusion Techniques Allow Production of Cermet Segments
• Cermet mixture placed in long rectangular box− Layer of powder mixture
added− Layer compressed− Steps repeated until box
is full
• Box welded shut
• Box heated and gases removed
• Box heated and extruded to final form
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Powder Extrusion Process(Ram Pushes Heated, Canned Powder
Through a Die)
05-056
Powder(Hot)
Can
DieHydraulic
Ram
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Powder Mix Segregation Tests
• Powder mixtures can separate on handling
• Tests define allowable thickness of powder before compression− 7-cm cylinder of HfO2
mix and iron powder− 2-hours on vibration
table− Limited segregation
• Tests define maximum layer of powder mixture before pre-compaction
0 10 20 30 40 50
6
20
37
55
73
91
Steel Powder Content (wt%)
Dis
tanc
e fro
m B
otto
m o
f Sam
ple
(%)
37.4
42.6
44
44
44.3
44.8
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Compression Testing
• Powder mix compressed to minimize high-temperature consolidation
• Tests to determine optimum forces for compression− Low pressure
minimizes cost− High pressure
maximizes density− Warm compaction
above Tg of binder improves density 10
30
Compaction Pressure (ksi)
Den
sity
(% T
.D.)
15 20 25 30 3550
40
50
60
70
8025º C120º C
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Advantages For Each Process
FCC Process CES Process
• Maximize cermet content of cask (no steel inside cask body)− Maximize performance− Maximize DUO2 usage
• Minimum number of process steps− Advantage for large
volume production
• Small manufacturing equipment (low capital cost)− Attractive for limited
production runs
• Lower research and development costs
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Conclusions
• Two methods for cask manufacturing are being investigated
• Both methods use powder metallurgical fabrication processes
• Each has specific advantages and disadvantages
• Experiments are required to determine manufacturing times to allow reliable estimates of manufacturing costs
• Cost estimates to be developed latter this year