Framatome Gmbh

Framatome & Cie.

Alain Gravelle

Jean Marini

Jean-Claude Weilbacher

Dominique Romy

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).

Device for locating the position of control rods of a nuclear reactor

Method and apparatus for monitoring the movement of the control rods of a nuclear reactor. The number of steps of movement in either direction of the rod from which the control rod is suspended is counted. According to the height of the step, an indication of the position of the suspension rod and of the control rod. The apparatus comprises devices for measuring the speed of movement of the control rod, for logging variations in speed higher than a given value, and for counting such variations according to their sign. The invention is particularly useful in pressurized water nuclear reactors.

Method and apparatus for monitoring the control rods of a nuclear reactor

Method and apparatus for detecting defective fuel elements in a nuclear reactor assembly. The assembly (20) is kept entirely immersed in a liquid such as water, ultrasonic waves are propagated successively in each of the fuel elements of the assembly or rods (21), an ultrasonic sensor (25) is disposed near the assembly (20) and the waves which may be scattered into the protective liquid by the defects in the fuel rod are picked up to determine the presence of a defective assembly and locate the defective rod in the assembly. The invention is particularly applicable to fuel assemblies of a pressurized water nuclear reactor.

Method and apparatus for detecting defective fuel elements in a nuclear

Gases contained in the sheaths of the fuel elements are made to expand in order to cause the escape of gas bubbles in the protective liquid into which the fuel assemblies are immersed. The progress of the gas bubbles in the protective liquid is arrested by means of a screen (1) located above the assembly and an acoustic phenomenon associated with the impact of the gas bubbles on the screen or with the accumulation of gas below the surface of the screen is recorded. The appearance of this acoustic phenomenon permits the detection of defective assemblies. The invention applies in particular to pressurized water nuclear reactors.

Process and apparatus for acoustic and ultrasonic detection of defective

A method of testing new fuel rods for assemblies for nuclear reactors. Ultrasonic waves are transmitted in the canning tube of the fuel element disposed in the open, with an oblique incidence with respect to the axis of the tube, from one region of the side wall of the tube. By reflection at the walls of the canning tube, these waves produce plate waves or Lamb waves. These Lamb waves are picked up after a certain distance has been covered along the length of the canning tube and the attenuation undergone by these Lamb waves is measured. From this, by comparison with the attenuation results obtained at another part of the length of the tube or with a standard tube, data on the possible presence of moisture in the fuel rod is deduced. The invention particularly applies to the testing of fuel rods of assemblies for a pressurized water nuclear reactor.

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Le Plessis Robinson, France

Alain Gravelle