Characterization of disbonds in a nuclear radiation protection structure (NRPS) has been investigated by laser ultrasonics. Characteristics of laser ultrasonic waves in an NRPS have been researched by simulations and experiments. The signal-to-noise ratio of laser ultrasonic signals in the adhesive structure can be improved by wavelet threshold de-noising (WTDN) and band-pass filtering. Original laser ultrasonic signals were processed by WTDN to implement C-scans which have high contrast to noise ratio. Laser ultrasonic C-scan results can accurately characterize the disbonds, which are in reasonable agreement with the immersion ultrasonic detection result. Therefore, laser ultrasonics has potential for non-destructive evaluation of the bonding quality of NRPSs.