Beam Steering Technique of Ultrasonic Waveguide Sensorfor Under-Sodium Inspection of Sodium Fast Reactor

摘要

The reactor core and internal structures of asodium fast reactor can not be visually examined dueto the opaque sodium. The under sodium inspectiontechnique using an ultrasonic wave should be appliedfor the in-service inspection of the reactor internals.Immersion sensor and waveguide sensor have beenutilized for the under-sodium viewing application.The immersion sensor has a precise imagingcapability, but may have high temperature restrictionsand an uncertain life. The waveguide sensor has theadvantages of simplicity and reliability, but limits inits movement. In this study, new ultrasonictechniques are being developed to overcome thescanning limitation of a waveguide sensor. A newtechnique is presented which is capable of steering anultrasonic beam of an waveguide sensor without amechanical movement of the sensor assembly. Thesteering function of the ultrasonic radiation beam canbe achieved by a frequency tuning method of theexcitation pulse in the dispersive low frequency rangeof the A0 Lamb wave.