| 摘要 |
PURPOSE:To determine the gap between the upper mechanism of a reactor core and a floated fuel assembly quantitatively, by transmitting and receiving an ultrasonic wave beam to and from many isotropic scattering bodies at the upper end surface of the fuel assembly by an ultrasonic wave transducer. CONSTITUTION:An ultrasonic wave transducer array, which is located at the approximately same height as a core gap, transmits a narrow ultrasonic wave beam in the horizontal direction based on the control signal of a measuring and controlling circuit 10A. The scattered reflected light is received again. Many semisphericl convex isotropic scattering bodies 23, which have the same size as the ultrasonic wavelength or more, are arranged on the outer surface of an upper end cylindrical part 22 of the fuel assembly. Therefore, part of the reflected light is positively received, and its position is determined based on the distance and angle to the fuel assembly. Therefore, the gap between the floated fuel assembly in the core gap and an upper mechanism 3 of the reactor core can be quantitatively determined. |
