A CARBON-CARBON REPAIR SYSTEM FOR THE FIRST WALL OF THE INTERNATIONAL THERMONUCLEAR EXPERIMENTAL REACTOR

HIGH THERMAL CONDUCTIVITY CARBON-CARBON COMPOSITES ARE CANDIDATES FOR THE FIRST WALL OF THE INTERNATIONAL THERMONUCLEAR EXPERIMENTAL REACTOR (ITER). HOWEVER, CARBON-CARBON COMPOSITES HAVE RELATIVELY HIGH EROSION RATES CAUSED BY HYDROGEN BOMBARDMENT WHEN THE PLASMA DISRUPTS. SUCH EROSION MAY REQUIRE FREQUENT REPLACEMENT OF THE FIRST WALL PANELS AND TILES, SERIOUSLY REDUCING THE DUTY FACTOR OF THE REACTOR. THIS PROGRAM ATTEMPTS TO DEVELOP A SYSTEM TO EFFECT IN SITU REPAIR OF THE DAMAGED CARBON-CARBON SURFACES (WITHOUT REMOVING THE ORIGINAL PANELS OR TILES). THIS SYSTEM DELIVERS A MIXTURE OF HYDROCARBON GAS AND FINE HIGH THERMAL CONDUCTIVITY VAPOR-GROWN FIBERS OR GRAPHITE POWDER TO A NOZZLE FOR MIXING, HEATING, AND DEPOSIT OF A FIBER-REINFORCED ISOTROPIC CARBON DIRECTLY ONTO THE DAMAGED SURFACES. THE STRUCTURE OF THE REPAIR CARBON COMPOSITE IS TAILORED BY CONTROLLING THE DEPOSITION CONDITIONS TO MATCH THE ORIGINAL CARBON-CARBON. IN PHASE I, A MODEL FOR THE CARBON DEPOSITION PROCESS IS BEING DEVELOPED. THE MODELLING WORK GUIDES THE CONCEPTUAL DESIGN OF THE SYSTEM. PRELIMINARY DESIGN IS BEING COMPLETED IN PHASE I. THE EQUIPMENT WILL BE CONSTRUCTED IN PHASE II AND OPERATED TO ESTABLISH WORKABILITY. AN EXPERIMENTAL PROGRAM BASED ON THE MODEL DEVELOPED IN PHASE I WILL BE IMPLEMENTED TO OPTIMIZE DEPOSITION CONDITIONS. THE STRUCTURE OF THE REPAIR CARBON WILL BE ANALYZED, AND DEPOSITIONS WILL BE ESTABLISHED TO MATCH THE ORIGINAL CARBON-CARBON. SPECIMENS OF THE REPAIR CARBON WILL BE FABRICATED FOR IRRADIATION AT OAK RIDGE NATIONAL LABORATORY.