Hitachi-ge Nuclear Energy, Ltd.

Hitachi, Ltd.

Motoyuki Nakamura

Yoshio Nonaka

Naoyuki Kono

Masahiro Miki

Satoshi Shinohara

Isao Yoshida

Masahiro Koike

Akira Nishimizu

Akihiro Taki

An object of the present invention is to provide an inspection apparatus for inspecting weld zones in a reactor pressure vessel, the inspection apparatus comprising: an ultrasonic probefor emitting an ultrasonic wave; a probe holding unitfor holding the ultrasonic probesuch that a ultrasonic wave transmitting surface of the ultrasonic probeis kept in direct contact with or at a constant distance from the outer surface of the reactor pressure vessel; a pressing unitfor pressing the probe holding unitparallel to a central axis of a control rod drive housingagainst the reactor pressure vessel; and a rotatorfor rotating the probe holding unitand the pressing unitabout the central axis of the control rod drive housing

Apparatus for ultrasonic inspection of reactor pressure vessel

The surface length of a metal subject to be inspected is evaluated by detecting an eddy current without using a combination of a scale and visual or liquid penetrant inspection. An exciting coil and a detecting coil are scanned above the subject in a length direction. An eddy current detector measures an output voltage corresponding to scanning positions based on an output from the detecting coil. Based on an output voltage distribution curve indicating a distribution of output voltages corresponding to the scanning positions, position information is extracted corresponding to values which are within a differential voltage range and lower by 12 dB than a maximum value of the output voltages on the left and right sides of the distribution. A distance between the positions included in the extracted information is calculated to evaluate the length of a slit which is a defect present on the subject surface.

Method and apparatus for evaluating length of defect in eddy current testing

The ultrasonic probe of the ultrasonic inspection apparatus, which is pushed onto the outer surface of the reactor pressure vessel, transmits and receives an ultrasonic wave to and from a penetration having a welded portion while changing an incident angle of the ultrasonic wave. Based on a result of reception of an echo obtained by the reflection of the ultrasonic wave on the inner surface of the penetration, an inclination angle of the penetration relative to a wall surface of the reactor pressure vessel is measured. A circumferential direction position of the penetration, which corresponds to the inclination angle, is calculated based on the relationship of an inclination angle and a circumferential direction position, which have been calculated in advance. Then, the circumferential direction position can be obtained as information on the inspection position.

Method and apparatus for ultrasonic inspection of reactor pressure vessel

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Hitachi, Japan

Motoyuki Nakamura