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Electrometallurgical Techniques for DOE Spent Fuel Treatment: Final Report
Preliminary Discussion of Findings and Recommendations
SEPTEMBER 21, 1999—AGENDA
Closed Session—Findings and Recommendations for the Final Report
Final Agreement on Findings and Recommendations
Outstanding Issues—Post Meeting Requirements, Planning Schedule for Completion and
Release of the Committee’s Final Report
SUMMARY OF PRESENTATIONS
Robert W. Benedict, ANL, spoke to the committee about the spent fuel demonstration project status. He gave the following summary of the repeatability results for driver electrorefining. The specific success criterion goal was to freeze process modifications and operating parameters while demonstrating a continuous throughput of 16 kg of driver uranium per month over a 3-month period. The repeatability demonstration began on November 14, 1998, and ended on January 22, 1999 (61 working days). The average treatment rate was approximately 24 kg per month.
For the blanket throughput, demonstration results were as follows. The specific success criterion goal was to treat 150 kg of blanket uranium in 1 month. The 1-month demonstration began on July 17, 1999, and ran through August 15, 1999 (30 days). The unit throughput for the blanket chopper was 164 kg; for the Mark-V electrorefiner, it was 205 kg; for the cathode processor it was 206 kg; and for the casting furnace it was 177 kg.
Mark-V electrorefiner process improvements since the completion of the throughput demonstration include the following. Stall recovery software has been implemented. The software automatically restarts the anode rotation after a stall. Using the demonstration operating conditions, the average production rate increased from 212 g of uranium per hour to 260 g of uranium per hour. Anode agitation software has been implemented along with stall recovery software. The software rotates that anode 90 to 180 degrees forward, then 45 to 90 degrees backward continuously. This greatly reduces the tendency to stall (0-4 stalls per product collector versus 16-20 stalls in the demo mode). The average production rate was increased to 350-400 g of uranium per hour.
Significant achievements for the Mark-V electrorefiner include the following. The latest run allows 400 g of uranium per hour per ACM as the average production rate, with 60 percent equipment utilization per ACM. The four ports are operational. Operation of the four ports is simultaneous, with routine operation of two ports possible. More than 13 blanket assemblies have been treated. Control software allows unattended operation. Two product collector harvesting methods have been developed: a bake-out oven with a gravity-assisted product dump at 500 °C, and a product collector harvesting tool that has a rotating multibladed tool used for grinding out product at room temperature.
The cathode processor treated 40 driver batches, 14 blanket batches, and 8 cladding hull batches. The casting furnace treated 40 driver batches, 14 blanket batches, and 7 metal waste batches.
For the driver fuel, the cathode processor/casting operating conditions were as follows. The cathode processor has a maximum crucible temperature of 1200 °C. The operating pressure was 0.1 torr, with isolation for cadmium. The salt distillation step took place over 1 hour at 1100 °C. Casting took place with a maximum crucible temperature of 1300 °C. The operating pressure was 900 torr until cast, and there was one stir cycle.
Significant accomplishments in the treatment process include the following. Driver treatment has processed 100 driver assemblies in 3 years. Eight assemblies were treated in 1 month. One thousand one hundred and ten kilograms of low-enriched uranium were cast. The cathode processor batch size increased from 12 to 19 kg. The casting furnace batch size increased from 36 to 54 kg. Blanket treatment has processed 13 of 25 blanket assemblies. The Mark-V electrorefiner has run 21 batches of irradiated blankets. Three hundred fifty five kilograms of blanket product have been cast. The blanket element chopper is operational.
Results for metal waste casting include the following. Three MWF ingots in the FCF that each accommodate