| 摘要 |
PURPOSE:To obtain the picture of the image of the upper end surface of a reactor core at high resolution, by scanning the upper end surface of a fuel assembly, in which many isotropic scattering bodies are arranged, by the fan beam of an ultrasonic wave transducer, thereby receiving the beam positively. CONSTITUTION:An upper mechanism 3 is moved when fuel is replaced. A fan beam is projected on the upper end surface of a fuel assembly 21 in a reactor core 2A from an ultrasonic wave transducer 7A, which is moved in a horizontal plane. The scattered reflected light is received again. A measurement controlling circuit 9A, which controls the timing of transmission and reception, processes the distance direction and the azimuth direction, with the length of synthesized aperture being a processing unit. The image of the upper end surface of the reactor core 2A is made to be a picture. On the upper end surface of a handling head part 22 at the top of the fuel assembly 21, many semispherical convex isotropic bodies 23 having the size that is about the same as or larger than that of the ultrasonic wavelength are arranged. Therefore, the ultrasonic wave beam is scattered in an isotropic pattern. The beam is positively received, and the image of the upper end surface of the reactor core can be made to be a picture at high resolution. |
