Makoto Senoh

Development of shape measurement system using an omnidirectional sensor and light sectioning method with laser beam scanning for Hume pipes

A shape measurement system for Hume pipes (diameter 1200 to 2000 mm) is developed using an omnidirectional sensor and a light sectioning method with laser beam scanning to evaluate degradation of Hume pipes. This system can measure the inner wall shape of Hume pipes at high speeds (about 3000 distance measurement points within 3 s) and high accuracy while moving along the pipe axis, and it can evaluate the corrosion quantity of the pipe wall surface. To measure the 3-D shape, the system is developed using an omnidirectional imaging device combined with a laser beam for slit light projection, and a hyperbolic mirror and high-precision digital camera. Also, an algorithm is developed that calculates position coordinates of the camera optical axis and posture with the distance data from the camera optical axis to the pipe wall surface. Performance test results of the developed system have accuracy in a shape measurement of about 3 mm for distances of 400 to about 1600 mm.

Unknown sound evaluating method and apparatus

Method and apparatus for evaluating location of an unknown sound generated in a structure such as a pressure vessel. A plurality of sound detectors are mounted on the structure for detecting sounds generated in the structure. On the basis of sound information of the unknown sound source derived from the outputs of the detectors, the location where the unknown sound is produced is determined. To this end, reference sounds are first generated at a plurality of known reference sound source positions, wherein information of the reference sounds derived from the outputs of the detectors are stored in a storage unit. Equi-pattern-distance curves each of which is in an equal pattern distance between a supposed unknown sound source and each of the reference sound sources are calculated on the basis of the reference sound information. The equi-pattern-distance curves are further corrected in accordance with the reference sound information. Upon occurrence of an unknown sound, pattern distances between the desired reference sound source positions and the unknown sound source position are calculated through pattern recognition procedure from the sound information derived from the outputs of the detector and the reference sound information stored. On the basis of the calculated pattern distances and the equi-pattern-distance curves, the position of the unknown sound source is determined. On the basis of the position of the unknown sound source, kinetic energy thereof may be arithmetically determined.

Fuel-Number Recognition by Means of Multidirectional Lighting

Lighting and image-processing techniques for automatic fuel-number recognition in boiling water reactors (BWRs) are described. High-contrast images of fuel numbers are obtained for various types of fuel subassemblies by intorducing shallow-angle lighting. Moreover, high-quality binary-valued images can be obtained by miltidirectional lighting and character reconstruction techniques. These techniques are esperimentally confirmed using subassemblies. The multidirectional lighting is verified to be superior to unidirectional lighting in terms of its recognition rate and its applicability to an automatic fuel-number recognition system for BWRs.

Methods of metallic loose parts location and impact energy estimation from information on reference impact sounds

Abstract Reference impacts were employed to achieve accurate location and energy estimation of metallic loose parts in inhomogeneous systems such as nuclear reactor vessels. Impact positions are determined using distances from reference impacts and pattern recognition technique. To confirm the method, experiments were carried out using a cylindrical steel tank (diameter = 2m, height = 5m, thickness = 2m). The reference impacts were arranged on lattice points, separated by 1 meter, on the tank wall. The signal amplitudes of various impacts positions with a uniform impact energy and the same propagation path length exhibited deviations of around one order of magnitude. This fact would seem to limit the posibility of achieving accurate location and energy estimations from the amplitude data. However, the results were surprisingly good. Using amplitude data, the impact positions on the tank were located within an error of 13cm and impact energies were estimated within an error of 25%.