A Multi-Function Cermet Spent-Nuclear-Fuel Super Cask Presenter: Donald Kovacic

Author: Charles Forsberg

Oak Ridge National Laboratory P.O. Box 2008; Oak Ridge, TN 37831-6179 Tel: (865) 574-6783; E-mail: [email protected]

Paper: 81 Institute of Nuclear Materials Management 44th Annual Meeting Session: E: Packaging and Transportation: Packaging Design and Transport Operations Wednesday July 16, 2003 Phoenix, Arizona

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: Cermet_Super_cask: Supercask.INMM.2003 Outline

• Observations • Traditional Spent Nuclear Fuel (SNF) Management Strategy • Multifunction Cask System − Minimum SNF handling • Super Cask • Conclusions Observations

• The light-water-reactor (LWR) fuel cycle was designed for recycle of spent nuclear fuel (SNF) and evolved into a once-through fuel cycle • A once-through system designed as a once- through system would be significantly different from the existing one • Proliferation, safeguards, security (terrorism), and economics suggest that the once-through fuel cycle needs to reexamined • A new approach to SNF cask operations and design should be considered Traditional Approaches to SNF Management Imply Multiple Handling of Individual Assemblies with Associated Costs and Risks

Nuclear Reactor

Transport with Transport Inner Cask and Overpack Package Overpack

SNF SNF Assembly Assembly Storage Pond SNF Storage Cask Transfer Transfer Repository at Reactor Assembly (Store as is) Waste Transfer Package

Repository

02-088 A New SNF System (Reactor to Repository) Is Proposed to Accomplish Two Objectives

• Minimize SNF handling − Reduce security and safeguards risks − Avoid SNF transfer risks − Avoid SNF transfer costs • Secure SNF packages (Super Casks) Multi-Function Cask System

System Design To Minimize SNF Handling And Thus Reduce Safeguards and Security Issues SNF Is Placed in a Multifunction Cask (Mobile 100-ton Vault) and Never Removed (SNF Is Loaded at Reactor into Cask; Cask Is Used for Storage, Transport, and Disposal)

Nuclear Reactor

Repository Overpack Transport Overpack Cask

Transport Storage Pond SNF Storage (Multifunction Cask with Disposal at Reactor Assembly (Multifunction Cask Transport Overpack) (Multifunction Cask Transfer with Overpack-If Short with Disposal Overpack) Cooled SNF)

Repository

03-145 The Multifunction Cask Has Multiple Functions (Handling, Shielding, Protection, and Safeguards)

Dry Store Transport Repository Disposal (At Reactor)

Cask Removable Repository Overpack Overpack (2 cm C-22) Transport Surface Facility Overpack Cask Minimal Facility No SNF Shuffle (Surface Store SNF for Heat Management)

Underground Multifunction Cask Functions (Intact Package) One-Time SNF Handling No Remote Operations Container Redundant/Alternative Barrier Shielding Protection - Assault - Accidents Safeguards

03-146 Overpacks Address Conflicting Storage, Transport, and Disposal Requirements of Multifunction Casks

Dry Store Transport Repository Disposal (At Reactor)

Cask Removable Repository Overpack Overpack (2 cm C-22) Transport Surface Facility Overpack Cask Minimal Facility No SNF Shuffle (Surface Store SNF for Heat Management)

Underground Overpack Functions (Intact Package) Storage: Heat Removal No Remote Operations Transport: Accident Protection Redundant/Alternative Barrier Disposal: 10,000 year lifetime

03-147 Strategy Minimizes SNF Pool Storage (Safeguards and Security Concerns) Multifunction Casks Provide Superior Protection Against Theft or Diversion Fuel Assembly Multipurpose Cask

Large weight (>70 tons), Low weight (~1/2 ton), large size, detectable from small size from orbit, option of transponder

02-087 Cask Size And Weight Limits Thief Potential (German GNS SNF Storage and Transport Cask on a Railcar) Super Cask

New Technologies May Enable Manufacture of Economic Cermet Super Casks Cermets (Ceramics in Metal Matrix) Provide Protection Against Assault and Accidents • Cermets (left) are the traditional material for use in extreme environments Main Battle • Cermets combine the best Tank Armor properties of metals and Brake Shoes ceramics • Metals • Ductility • Thermal conductivity Cutting Tools • Strength

Test Reactors • Ceramics (UO -Steel Cermets) 2 • Shielding • Hardness (Armor) • Other

03-108 Cermets (Ceramics in Metal Matrix) Are the Enabling Technology for a High- Performance Super Cask

Functions Graphite/SiC/ Other Ceramics Edge Void Radiation Shielding Space Steel (Continuous SNF Assembly Phase) 2 Slot - Gamma: High-Density DUO /Other Depleted Uranium - Neutron Moderation/Absorption Dioxide (DUO2 ) Oxygen in DUO2 Carbon in SiC and Graphite Assault Protection: Multilayer Cermet Clean Steel Cermet (Traditional Armor) - Ceramic (Al 23O,DUO 2 , SiC, Other) - Metal Safeguards and Theft - Large Mass - Vault Construction: Multilayer Cermet Decay Heat Removal - High Conductivity Steel Matrix

02-095R The Composition Across the Cermet Can Be Varied to Maximize Performance

Ceramics for Armor Clean Steel Protection (Traditional Cermet Application) - DUO2 - Al23 O - SiC Ceramics for Neutron Moderation or Absorption - DUO2 - SiC - Gd23 O Ceramics for Gamma Shielding - DUO2 Metal Matrix Cask Body - Strength - Thermal Conductivity

02-115R New Cermet Cask Production Method Is the Potential Enabling Technology for Economic Cermet Casks (Patents pending; See paper for details)

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 Vacuum Seal Preform 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)

03-148 Conclusions

• Protection of SNF is enhanced by − Reduced operations − SNF placement in strong casks • Two technical developments create the potential for a more secure SNF management system − Multifunction cask system to minimize handling − Manufacturing method for economic production of a cermet super cask • The once-through fuel cycle should be reexamined in light of new technologies and changing conditions Backup Viewgraphs New Fabrication Method (Patent Applied for): 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 Cask Preform Is Mounted Upside Down on Turntable and Filled with Cermet Particulate Mixture

Advanced Option

Integrated Cermet Hydraulic Cask Bottom Lift Particulate Fill Line Materials Feeder

Inside Bottom of Cask

Feed System

Cask Preform (Near Final Dimensions) Different Cermet Particle Mixes Tamping 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 seal preform Final Cask Particle Mix • Degas − Heat − Vacuum • Send sealed package to forging operations

Future Top Flange

03-107 Step 4: Loaded Preform Is Heated and Consolidated into Monolithic Cask

Cermet • Preheat to ~1000ºC Preform Anvil − Reduces required forging pressures − Welds iron particulates together

Idle • Two consolidation Roller options Drive Roller − Traditional forging (Top)

Axial − Ring forging (Bottom) Rollers • Yield monolithic final product

Cermet Preform 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 In Severe Environments, Casks Have Potential Advantages over Pools and Other SNF Storage Methods (Casks Used to Meet German Aircraft Collision Resistance Requirements)

Limited Inventory (Limited Consequences)

Impact Resistance Thick Walls Cask Recoil Passive Cooling (Consequence of Limited Inventory) Fire Resistance High Thermal Inertia Drain Fuel

01-021 German Rail Gun for Testing Casks: 1-ton Projectile at 300 m/s (Simulate Aircraft Jet-Engine Rotor)