Characteristics and Fabrication of Cermet SNF Casks (Ceramic Particulates Embedded In Steel)
Speaker: Scott Ludwig Charles W. Forsberg Paul M. Swaney Terry N. Tiegs
Oak Ridge National Laboratory* P.O. Box 2008; Oak Ridge, TN 37831-6165; United States of America Tel: (865) 574-6783; E-mail: [email protected]
PATRAM 2004 14th International Symposium on the Packaging and Transport of Radioactive Materials Session: 4.15; Gamma Shielding Materials September 23, 2004, 3:30-p.m.-5:10 p.m. Berlin, Germany
*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: PATRAM-2004 Outline
• Cermet Cask Description • Manufacturing • Conclusions
GNS Storage and Transport Cask Cermet Cask Description
Cermet (Definition): Ceramic Particulates Embedded In Metal Cermets Combine the Best Properties of Ceramics (Shielding, Hardness, etc.) and Metals (Strength, Ductility, etc.) Cermets Are Used for Cermet Body Cross Section Demanding Applications Clean Steel Ceramics
-Armor (Al2O3, Brake Shoes SiC) - Neutron Shielding
(DUO2, Gd2O3) - Gamma Shielding
(DUO2) Metal Matrix Main Battle - Strength Tank Armor Cask Body - Thermal Conductivity Cutting Tools
04-070 Cermets are the Enabling Technology for a SNF Super Cask (Ceramics in Metal Matrix to Obtain Advantages of Both)
Cermet Al2O3, Other Ceramics • Radiation Shielding Cask Steel (Continuous − Gamma: High-Density DUO2/Other SNF Assembly Phase) − Neutron Moderation/Absorption Slot Depleted Uranium • Oxygen in DUO2 Oxide • Carbon in SiC/Other Cermet • Assault Protection: Traditional Armor − Ceramic (Al O , Other) Clean Steel 2 3 − Metal Safeguards and Theft Armor • − Large Mass Hard Ceramic − Cermet Breaks up Projectile • Decay Heat Removal − High-Conductivity Steel Matrix Projectile • Geological Disposal
Ductile Metal − Criticality (DUO2) Absorbs − Chemistry: Enhanced Eh and pH Energy (Fe, Other)
04-100 Cermets Enable the Design of Higher-Capacity SNF Casks for a Given Weight
Variable-Density Cask Wall Low-Density Ceramic (Low Radiation Shielding Needed) 100000 High-Density Ceramic 316 Stainless Steel 10000 Cermet: 50 vol % DUO2
1000 Cermet: 90 vol % DUO2 Transition from gamma 100 to neutron dose control
Superior Shielding 10
DUO2 Particulates 1
Steel Matrix RadiationLevl(/h) Radiation Level (R/h) 0.1
0.01
0.001 0 5 10 15 20 25 30 35 40 45 50 Thickness (cm)
04-071 Cermets Enable the Design of Armored Casks
• Cermets are the traditional armor Hard Ceramic • Single materials can be Breaks Up destroyed by matching Projectile assault to specific material weakness • Cermets have “multiple” Projectile properties
• “Hard” ceramic breaks up Ductile Metal projectile or shaped charge Absorbs Energy • “Ductile” metal absorbs energy
04-071 Cermets Enable Waste Package Designs to Maximize Repository Performance
Cf-251 902 y SCML = 5 g Bk-247 1400 y ←Depleted Uranium In Cm-243 Cm-247 29 y 15.6x106 y Appropriate Chemical Form for SCML = 90 g SCML = 900 g Am-243 EC 99.8% 0.2% 7370 y SCML = 25,000 g Criticality Control Pu-239 Pu-243 24.1x103 y 4.96 h SCML = 450 g Np-239 350 0 2.35 d CM = No Cermet and Fill WP 1 U-235 U-239 300 Cermet and Fill WP, 700x106 y 23.5 m YM WP Cermet WP 2 SCML = 700 g Pa-231 250 32.5x103 y 3 CM = Yes Start of SNF UO 2 4 Th-231 200 Oxidation (Idealized)
25.5 h ( ) aining 5 m e Cermet WP R 150
pH ( ) ( pH
2 6
Adjust Cask Chemical O U 7
ol 100 m Composition To Create k 8 50 Geochemical Environment to YM WP 9 010 0100200 300 400 500 Slow SNF Degradation→ Oxygen (kmol)
0 0.51.0 1.5 2.0 2.5 Time (millions of years) Manufacturing
New Methods Being Developed
If Successful, Cermet Casks Are Viable Low-Cost Manufacturing is the Key Economic Requirement • The fundamental characteristics of cermets make them superior to other potential cask materials − Superior performance (shielding, armor, etc.) − Low-cost raw materials • Cermet cask feasibility depends upon development of low-cost fabrication methods • Two methods are being investigated − Powder metallurgy (United States: herein) − Casting (Russia) New Cermet Cask Production Method (United States: Patent Application Filed)
Steel/DUO2 Add Steel/DUO2 Particulate Fill Particulate Fill Consolidate Particulates to Cermet to Annular Steel Shells Preform Forge or Roll Idle Roller Drive Weld and Roller Seal Preform Vacuum Anvil Axial and Degas Degas Rollers Powder Mix
Future Cask Cermet Lid Mating Preform Surface
Heat Machine Cask Lid Preform Mating Surfaces Weld Bottom onto Package (Steel-to-Steel Weld)
02-090R3 Step 1: Manufacture of Cask Preform
Outer Surface of Inner Surface Final Cask • Preform dimensions are Void 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
03-105 Step 2: Empty Preform is Mounted Upside Down on Turntable and Filled with Cermet
Advanced OptionParticulate Mixture
Integrated Cermet Hydraulic Cask Bottom Lift Particulate Fill Line Materials Feeder
Inside Bottom of Cask
Feed System
Cask Preform (Near Final Dimensions) Tamping Different Cermet Particle Mixes Arm Preform Rotating Platform
Particulate Mix
02-119R
Future Top Flange Step 3: Loaded Preform is Sealed and Degassed
• Weld annular ring to Inner Surface Outer Surface of Final Cask seal preform Particle Mix • Degas − Heat − Vacuum • Send sealed package to forging operations
Future Top Flange
03-107 Step 4: Cermet Consolidation by Hot Forging (Several Forging Options)
Cermet Preform Anvil
02-116 Step 5: Cask Finishing Operations
• 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
03-104 Status of Work
• Concept of cermet cask developed • New cask fabrication methods are being developed • Preliminary analysis indicates good economics • Detailed manufacturing time and cost studies underway Conclusions: Cermets Enable Advanced Casks if Low-Cost Manufacturing Methods are Successfully Developed Clean Steel Ceramics ←Cermet Cask Bodies
-Armor (Al2O3, SiC) - Neutron Shielding Steel/DUO (DUO2, Gd2O3) 2 Add Steel/DUO2 Particulate Fill - Gamma Shielding Particulate Fill (DUO ) to Annular Steel Shells Consolidate Particulates to Cermet 2 Preform Forge or Roll
Metal Matrix Idle Weld and Roller -Strength Vacuum Drive Cask Body - Thermal Conductivity Degas Roller Powder Mix Axial Seal Preform Anvil Rollers and Degas Future Cask Lid Mating Surface Cermet Preform New Cermet Heat Preform
Manufacturing Machine Cask Lid Mating Surfaces Weld Bottom Methods→ onto Package (Steel to Steel Weld)