National Academy of Sciences Current Status of and Progress toward Eliminating Highly Enriched Uranium Use in Fuel for Civilian Research and Test Reactors Oak Ridge, TN June 2015 Y-12 National Security Complex U-Mo Fabrication Hollie Longmire hollie.longmire@cns.doe.gov 1
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Objectives • Initial phases of U-Mo Program at Y-12 • Progression of fabrication processes at Y-12 • Current fabrication process at Y-12 • Scrap recycle opportunities • Future process considerations 3
Initial Phases of U-Mo Program at Y-12 • Y-12 began preliminary alloy castings in 2006 • Preliminary casting molybdenum powder • Multiple melts required • Final product was heat treated and machined • Y-12 experimented with process variations to define a baseline process • Casting times • Casting temperatures • Casting geometries • Molybdenum forms: powder, rod and foil 4
Baseline Coupon Fabrication Concept 5
Alternate Casting Process 6
Proposed Optimized Casting Process 7
Coupon/Ingot Option Coupons Ingots • Center strip used for sampling • Sized determined by final foil • Larger ingots allow for greater requirements downstream processing • Requires specific cut diagrams flexibility • Increased material utilization 8
Optimized Casting Process: Campaign 1 Summary Weight Percentage of Uranium Weight Percentage of Molybdenum 93% 12% 92% 11% 91% 10% 90% wt% Mo wt% U 89% 9% 88% 8% 87% 7% 86% 85% 6% Top Middle Bottom Top Middle Bottom Sample Location Sample Location • Campaign 1 consisted of six castings • Each casting is three plates • Each plate is sampled three times: top, middle and bottom 9
Optimized Casting Process: Campaign 2 Summary Weight Percentage of Uranium Weight Percentage of Molybdenum 100.00% 12.0% 98.00% 10.0% Molybdenum Percent Uranium Percent 96.00% 8.0% 94.00% 6.0% 92.00% 4.0% 90.00% 2.0% 88.00% 0.0% Top Middle Bottom Top Middle Bottom Sample Location Sample Location • Campaign 2 consisted of eight castings • Each casting is three plates • Each plate is sampled three times: top, middle and bottom 10
Scrap Recycle Opportunities • Hot Top Recycle • Studies in progress • Chip Melting • Feasibility studies are complete • Greater that 90% yield/run • Continue studies to increase Technology Readiness Levels Recycled U-Mo Chips 11
Future Process Considerations • Surface Finish • Current process utilizes a machined surface finish • Studies underway to determine if as-cast surface is acceptable • Optimized Mold Geometry • As fuel fabrication processes are optimized, mold geometry can be adjust to reduce scrap and increase material utilization • Scrap Recycle Studies • Continue scrap recycle studies to optimize the re-use of recycled material 12
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