A DUAL LIQUID LEVEL MEASUREMENT SYSTEM FOR PYROCHEMICAL PROCESSING OF NUCLEAR FUELS

PHASE I OF THIS PROJECT ADDRESSES THE DEVELOPMENT OF A NOVEL LIQUID LEVEL MEASUREMENT SYSTEM CAPABLE OF ACCURATE SIMULTANEOUS DETERMINATION OF A LIQUID METAL/MOLTEN SALT AND A MOLTEN SALT/GAS INTERFACE POSITION. THE SYSTEM WILL BE APPLICABLE TO THE NEW PYROCHEMICAL NUCLEAR FUEL PROCESSING TECHNOLOGY UNDER DEVELOPMENT AT THE ARGONNE NATIONAL LABORATORY IN SUPPORT OF THE INTEGRAL FAST REACTOR CONCEPT FOR THE NEXT GENERATION OF NUCLEAR REACTORS. THIS DEVELOPMENT WILL APPLY THE PRINCIPLE OF THERMAL DIFFERENTIAL LIQUID LEVEL MEASUREMENT IN WHICH INTERFACES BETWEEN FLUIDS HAVING DIFFERENT HEAT TRANSFER CHARACTERISTICS ARE DETECTED BY THE DIFFERENCES IN RESISTANCE OF ELECTRICALLY HEATED ELEMENTS RELATIVE TO UNHEATED ELEMENTS IMMERSED IN, BUT ELECTRICALLY INSULATED FROM, THE FLUIDS. THE SYSTEM MUST OPERATE IN CORROSIVE FLUIDS AT A TEMPERATURE OF 500 DEGREES CENTIGRADE OR HIGHER AND IN THE HIGH NUCLEAR RADIATION ENVIRONMENT ASSOCIATED WITH FUEL REPROCESSING. IT MUST ALSO BE SIMPLE IN CONCEPT, RELATIVELY LOW IN COST, RUGGED, HAVE AN ACCURACY OF BETTER THAN 0.125 IN., BE REMOTELY INSERTABLE AND REMOVABLE FROM THE SYSTEM, AND BE RELIABLE AND SAFE IN OPERATION. DURING PHASE I, A PROTOTYPE UNIT IS BEING DESIGNED; AT LEAST ONE PROTOTYPE SENSOR IS BEING DESIGNED, FABRICATED, AND TESTED; AND A MATERIALS TEST IS BEING CONDUCTED. THE DESIGN OF THE SYSTEM IS BEING SUPPORTED BY TECHNOLOGY DEVELOPED AT THE OAK RIDGE NATIONAL LABORATORY DURING THE 1970S AND EARLY 1980S FOR OUT-OF-REACTOR THERMAL-HYDRAULIC SAFETY AND REACTOR CORE DESIGN INSTRUMENTATION. THE THERMAL DIFFERENTIAL MEASUREMENT SYSTEM TO BE DEVELOPED UNDER THIS GRANT HAS HIGH POTENTIAL FOR SATISFYING THE STRINGENT REQUIREMENTS OF THE APPLICATION, AND HENCE CAN CONTRIBUTE SIGNIFICANTLY TO THE VIABILITY OF THE NEW FUEL PROCESSING CONCEPT BY ENABLING ACCURATE FISSILE INVENTORY DETERMINATION AND CONTROL.