PRECISION MACHINING OF INTEGRAL FAST REACTOR METAL FUEL PINS WITH ARGON CUTTING JETS

HIGH-VELOCITY WATERJETS AND ABRASIVE WATERJETS HAVE BECOME VIABLE PRECISION CUTTING TOOLS FOR AWIDE RANGE OF APPLICATIONS. THIS PROJECT ADDRESSES THE USE OF ARGON LIQUID OR GAS CUTTING JETS FOR FABRICATING THE METAL FUEL PINS USED IN THE PYROMETALLURGICAL FUEL CYCLE OF ADVANCED REACTOR CONCEPTS. ARGON IS AN INERT GAS, AND IT IS THE AMBIENT ENVIRONMENT IN THE INJECTION CASTING FURNACES USED FOR FUEL PIN FABRICATION. THUS, AFTER CUTTING, NO LIQUID RESIDUE WILL REMAIN TO REQUIRE SPECIAL HANDLING. IN PHASE I, AN EXPERIMENTAL FEASIBILITY INVESTIGATION WILLBE CONDUCTED ON THE USE OF HIGH-PRESSURE (ABOUT 10 KSI) ARGON JETS FOR CUTTING THE FUEL PINS. AN ALTERNATIVE MATERIAL WILL BE USED THAT SIMULATES THE BRITTLENESS AND OTHER MACHINING CHARACTERISTICS OF THE URANIUM-PLUTONIUM-ZIRCONIUM ALLOY USED IN THE PINS. AB EXPERMINENTAL CUTTING SYSTEM WILL BE PREPARED TO STUDY THE CUTTING CAPABILITIES OF ARGON JETS. ARGON LIQUID, FROM COMMERCIALLY AVAILABLE CONTAINERS, WILL BE PUMPED UP TO ABOUT 10 SKI IN PRESSURE AND PROPELLED THROUGH SPECIALLY DESIGNED SMALL-DIAMETER NOZZLES (ABOUT 0.005 INCH) TO FORM HIGH-VELOCITY CUTTING JETS. THE METASTABLE LIQUID ARGON JET WILL BE USED TO ENTRAIN ABRASIVE PARTICLES SUCH AS GARNET (OR OTHER COMPATIBLE MATERIALS) IN SPECIALLY DESIGNED ABRASIVE JET NOZZLES. THE ABRASIVE-ARGON JET WILL THEN BE USED AS A PRECISION MACHINING TOOL TO CUT THE FUEL PIN TO LENGTH. AN ALTERNATIVE APPROACH OF USING THE LIQUID ARGON JET TO SCORE THE WORKPIECE SUCH THAT IT CAN BE SNAPPED WILL ALSO BE EVALUATED. TEMPERATURE CONTROL OF THE UPSTREAM FLOW AND NOZZLE GEOMETRY OPTIMIZATION WILL BE USED AS STRATEGIES TO MANIPULATE THE THERMODYNAMIC CONDITIONS OF THE ARGON JET. IN ADDITION TO ASSESSING THE TECHNICAL FEASIBILITY OF THE ARGON JET CUTTING, CONCEPTUAL DESIGNS WILL BE PREPARED ON HOW THE JET CUTTING TECHNIQUE WILL BE INTERFACED WITH CURRENT FABRICATION HARDWARE. ADVANCED PROTOTYPE SYSTEM DEVELOPMENT ACTIVITIES WILL BE IDENTIFIED FOR FABRICATION, TESTING, AND EVALUATION IN PHASE II. THE REMOTE OPERABILITY AND MAINTAINABILITY OF THE JET CUTTING METHOD ARE SIGNIFICANT ADVANTAGES THAT WILL BE EVALUATED IN THIS PROJECT.