Phased Array Ultrasonic NDE of Plasma Facing Components

The future of nuclear fusion relies in part on the development of effective plasma facing components (PFCs) that can withstand the intense heat loads, forces, and neutron bombardment of long-pulse, high-power reactor operation. Current PFC designs for the next-generation International Thermonuclear Experimental Reactor (ITER), which will require thousands of PFCs, involve beryllium (Be) armor bonded to a copper (Cu) heat sink. Because imperfections in the Be/Cu joint of just one in-service PFC would have potentially disastrous consequences, it is of great importance to nondestructively evaluate the integrity of PFC joints during manufacture. A suitable nondestructive evaluation (NDE) approach must accommodate the complex geometries of the components, provide 100% inspection of the joints, yield resolutions of one millimeter or less, and operate as part of the manufacturing process. This project will apply a revolutionary new NDE technique, phased array ultrasound, to the inspection of PFC joints. Unlike conventional ultrasound techniques, phased array ultrasound will provide: (1) programmable adjustment of focusing depth to achieve the best possible resolution at the desired spot; (2) versatile adjustment of the beam angle for forming images; (3) formation of focused ultrasound beams, even when traversing multiple layers of dissimilar materials having complex geometry; and (4) high-speed production inspection through electronic scanning of the active aperture across the face of the transducer array. Phase I will design and manufacture a phased-array transducer suitable for finding the defects that arise in joining PFCs ¿ in particular, at the joint between the armor and the heatsink. Then, the phased array transducer will be used to detect defects in actual PFC specimens. Commercial Applications and Other Benefits as described by the awardee: In addition to PFCs, the phased array ultrasound should be applicable to other components of fusion reactors involving the bonding of dissimilar metals. Other commercial applications would exist wherever defects arise within multilayer, complex geometries, such as in the nuclear, petrochemical, aerospace, and manufacturing industries.