Nondestructive evaluation of plate type nuclear fuel elements during manufacturing stage using ultrasonic test method

Structural discontinuities, such as cracks and bonding lacks at the core/cladding interface can be introduced in plate type nuclear fuel elements during the manufacturing stages, due to the mechanical and thermal processing conditions. They can reduce the performance of the nuclear fuel during its operational life or contribute to its premature failure. Plate type nuclear fuels (PTNF) consist of a core formed by a dispersion of UO2 into a metallic matrix, involved by a metallic cladding. Nondestructive testing methods such as eddy current, radiography and ultrasonic have been used to detect and monitoring discontinuities generated in the fuel's manufacturing stage, each one presenting advantages and limitations. The use of ultrasonic testing for this purpose presents two main difficulties: the small thickness of the plates as well as the presence of materials with different characteristics. The study described in this paper presents the methodology used in the evaluation of a prototype of PTNF by ultrasonic testing method, using different test techniques and transducers. The main results obtained and the next steps to be developed in this activity are discussed. (author)