RADIONUCLIDE-BASED MONITORING SYSTEM

THE FIRST WALL IN A FUSION REACTOR WILL BE EXPOSED TO AN EXTREMELY HARSH ENVIRONMENT CHARACTERIZED BY BOTH CONTINUOUS HIGH OPERATING TEMPERATURES AND VERY HIGH TEMPERATURE PULSES. SPECIALIZED COATINGS AND MATERIAL THAT CAN REJECT HEAT AND RESIST EROSION AND NEUTRON DAMAGE WILL BE REQUIRED. THESE MARTERIALS WILL REQUIRE TESTING IN ENVIRONMENTS THAT SIMULATE THE EXPECTED CONDITIONS IN FUSION REACTORS. IN ADDITION, METHODS FOR REMOTE MONITORING OF FIRST WALL EROSION WILL BE REQUIRED BECAUSE THE CONDITIONS AT THE FIRST WALL WILL PROHIBIT MOST CONVENTIONAL IN- SPECTION TECHNIQUES AND BECAUSE PREVENTIVE MAINTENANCE REQUIRING SYSTEM SHUTDOWN WILL BE DIFFICULT AND COSTLY. THE TECHNIQUE OF SURFACE LAYER ACTIVATION (SLA) IS PLANNED AS A METHOD FOR EVALUATING EROSION RESISTANCE DURING MATERIALS TESTING AND FOR REMOTE MONITORING OF SURFACE EROSION IN CRITICAL COMPONENTS IN FUSION EXPERIMENTS AND ULTIMATELY IN REACTORS. IN THE SLA METHOD, RADIONUCLIDES ARE FIRST INDUCED IN THE SURFACE BY A PARTICLE ACCELERATOR. BY DETECTING THE AMOUNT OF ACTIVITY REMAINING, THE SURFACE EROSION CAN BE CLACULATED. BECAUSE THE THECNIQUE IS HIGHLY ACCURATE AND NONINVASICE, IT IS IDEAL FOR RAPID MEASUREMENTS IN A CONTINUOUSLY OPERATING SYSTEM AND FOR LABORATORY TESTING OF THE MATERIALS. THE PLANNED RESEARCH WILL TEST WHETHER THESE EXPECTATIONS ARE STILL FEASIBLE IN THE PRESENCE OF BACK-GROUND RADIATION PRODUCED BY THE EXPECTED NEUTRON FLUX.