Applicabilty Study of Ultrasonic Flaw Detector For Nuclear Grade Graphite Examination

The development of High Temperature Gas-cooled type Reactor obliges the usage of nuclear class graphite as essential structure of reactor core. Nuclear class graphite requires an in-service inspection of NDT ultrasonic process to determine the declining rate of properties due to the used up amount of time. Yet, up to this moment, NDT ultrasonic is merely used limited to metal, and therefore the purpose of this research is to analyze the capability of ultrasonic flaw detector as an in-service inspection for nuclear class graphite. The method used in this measurement is the contact method by using the ultrasonic flaw detector with 2 MHz and 5 MHz probe. The material used for this purpose was IG-110 type nuclear class graphite. The results of these measurements show that the ultrasonic flaw detector may be well-functioned for the nuclear class graphite in the velocity of 2,450 m/s and the attenuation of 0.93 dB/mm. Besides that, the simulation result shows that the maximum propagation distance of the ultrasonic flaw detector may only reach up to the distance of 50 mm with the intensity of 31.5 dB for 2 MHz probe and 49.5 dB for 5 MHz probe.