| 摘要 |
Device for locating the position of a nuclear reactor control rod which is suspended from a shaft (12) sliding vertically inside an adaptor tube (10, 11) under the effect of a screw-nut mechanism which comprises a nut-forming rotor (14) mounted to rotate around the vertical axis of the tube (10) and provided with a threaded bore in which is engaged a corresponding threaded part (13) of the shaft (12). The device comprises a transmitter-receiver (2) of a beam of ultrasonic waves in a horizontal direction intersecting the axis (16) of the shaft (12), a wave-reflecting cylindrical surface (3) provided on the side wall of the rotor and having a cam-shaped profile in its perpendicular cross-section comprising at least one part (31) forming a slope over a narrow angular sector (A) whose distance from the axis varies rapidly between a minimum and a maximum, devices (2, 4, 5, 6; 64, 65) for forming impulses each of which corresponds to the passage of the slope (31) in front of the beam of ultrasonic waves during rotation of the rotor (14) and for recording and counting the successive impulses in either direction of rotation of the rotor (14). |
