USE OF CERAMIC FUEL CLADDING TO REDUCE THE SEVERITY OF LMR ACCIDENTS

THIS PROJECT INVESTIGATES THE FEASIBILITY OF USING CERAMIC CLADDING MATERIALS TO REPLACE THE METALLIC CLADDING MATERIALS NOW USED WITH WATER REACTOR FUEL. SHOULD FEASIBILITY BE DETERMINED, AND EVENTUALLY COMMERCIALIZED, THE ABILITY OF WATER REACTORS TO WITHSTAND SEVERE ACCIDENTS WOULD BE ENHANCED. WITH TODAYS METAL CLAD FUEL, A RELATIVELY SHORT TIME PERIOD IS AVAILABLE AFTER A LOSS OF COOLANT ACCIDENT BEFORE EMERGENCY CORE COOLING SYSTEMS MUST RECOVER THE CORE TO PREVENT FUEL DAMAGE. THE METAL CLADDING LOSES ITS STRENGTH AT RELATIVELY LOW TEMPERATURES (2200 DEGREES FAHRENHEIT). FURTHERMORE, WHEN THE METAL CLADDOES OVERHEAT AND IS SUBSEQUENTLY QUENCHED WITH WATER, IT REACTS EXOTHERMICALLY TO PRODUCE ADDITIONAL HEAT. ALTHOUGH THE FUEL PELLETS THEMSELVES ARE CERAMICS, WITH MELTING TEMPERATURES ON THE ORDER OF 5000 DEGREES FAHRENHEIT, CLADDING WHICH SUPPORTS AND CONTAINS THE FUEL PELLETS HAS ALWAYS BEEN FABRICATED USING LOWER MELTING METAL ALLOYS; CERAMICS WITH THE REQUIRED STRENGTH AND DUCTILITY WERE SIMPLY NOT AVAILABLE. RECENT TECHNICAL ADVANCES IN THE FIELD OF CERAMICS HAS PRODUCED NEW MATERIALS WITH DRAMATIC INCREASES IN DUCTILITY, STRENGTH AND FABRICABILITY. THIS PROJECT INVESTIGATES WHETHER THESE NEW DEVELOPMENTS WILL PERMIT USE OF CERAMIC FUEL CLADDING AND, THEREBY, REDUCE THE POTENTIAL SEVERITY OF CERTAIN ACCIDENTS IN WATER COOLED REACTORS.