RECYCLABLE MOLDS FOR CASTING NUCLEAR FUEL

RECYCLING SPENT NUCLEAR FUEL IS AN ECONOMIC NECESSITY FOR THE INTEGRAL FAST REACTOR. AFTER THE FISSION PRODUCTS HAVE BEEN REMOVED, THE IRRADIATED URANIUM FUEL MATERIAL CAN BE CAST INTO NEW FUEL RODS. THE CURRENT INJECTION CASTING PROCESS USES QUARTZ MOLDS THAT ARE NOT REUSABLE, SINCE THE MOLDS MUST BE BROKEN TO REMOVE THE CAST FUEL ROD. THE BROKEN MOLDS ARE RADIOACTIVE WASTE. HOWEVER, APPLICATION OFA SMOOTH, DENSE, ADHERENT YTTRIA COATING TO THE MOLD SURFACES BY CHEMICAL VAPOR DEPOSITION CAN ELIMINATE REACTIONS BETWEEN THE QUARTZ MOLD AND URANIUM FUEL. THIS WOULD PERMIT REMOVAL OF THE FUEL ROD WITHOUT BREAKING THE MOLD, ALLOWING IT TO BE REUSED. AN YTTRIA COATING PROCESS HAS BEEN DEVELOPED AND WILL BE USED IN PHASE I TO COAT QUARTZ MOLDS. SIMULATED CASTING WILL BE DONE TO ASSESS THERMAL SHOCK RESISTANCE AND EASE OF METAL CASTING REMOVAL FROM THE MOLD. POSITIVE PHASE I RESULTS, INCLUDING COST ESTIMATES, WOULD LEAD TO A PHASE II PROGRAM IN WHICH PILOT QUANTITIES OF YTTRIA-COATED QUARTZ MOLDS WOULD BE PRODUCED AND EVALUATED.