ABSTRACT
Monitoring degradation of the cladding of the fuel elements used in TRIGA type research reactors is typically performed using test methods such as visual test and sipping test. Although provide important information about the condition of the cladding, these methods do not allow determining the depth of the discontinuities detected neither monitoring their growth. In this paper is presented a study on the feasibility of using eddy current method for characterization of discontinuities in the AISI 304 stainless steel cladding of the fuel elements used in TRIGA type reactors. In this study, are described the reference standards for use in setting the test system and obtaining the reference curves of loss of thickness, test specimens used for the validation of the methodology used, the encircling probes and surface probes developed, the accessories and test metho dology used. The test system was able to detect the discontinuities located in the internal and external surfaces of the reference standards and test specimens and discriminate discontinuities with different depths. Discontinuities with diameter of 0.50 mm and depths above 50% of the cladding thickness as well as discontinuities simulating gradual loss of thickness were detected. It was also verified that the sensitivity provided by surface probes was considerably higher than the sensitivity of the encircling probes used.
Keywords:
eddy currents; TRIGA; fuel elements; nondestructive tests
