Abstract: A sealing device comprising a supporting assembly (9) containing sealing members (16) supporting the instrument column (5), and an assembly (17, 18) for lifting the instrument column (5) in sealing engagement with the supporting members (16). The sealing members (16) supporting the instrument column (5) include a clamping ring (28) and at least one O-ring seal (29, 30). Axial movement of the instrument column (5) enables clamping of the inner seal (30) via the clamping ring (28). When axial movement of the instrument column (5) is restricted, the seals may be clamped by means of a suitably sized clamping ring (28).

Abstract: The measurement device includes a means (18) for leaktight passage of a measurement conduit (20), produced in the form of a thimble, and an element (25) for connecting the end of the measurement conduit (20) to a smooth cylindrical extension element. The connection element (25) is produced in the form of a sleeve (26), the internal bore of which includes a first part (35) for receiving the measurement conduit (20) and a second part (36) for receiving the smooth cylindrical extension element. The connection element (25) includes, at the ends of the sleeve (26), a first removable means (28) for fastening and leaktight passage of the measurement conduit (20), and a second removable means (30) for fastening and leaktight passage of the smooth cylindrical extension element. The invention applies both to mobile-probe devices for measuring in the core of the reactor and to fixed-probe measurement devices.

Abstract: The instrumentation column (5) comes to bear via a bearing surface and a sealing gasket (16) inside a bearing element including a tubular length (8) and a closure cover (11) joined together by screwed assembly means. The tubular length (8) and the cover (11) each include a bearing surface (33a, 34) which is symmetrical of revolution about the axis of the instrumentation column (5). The bearing surface (33a) of the cover (11) and the bearing surface (34) of the tubular length (8) between them, through direct metal-to-metal contact, provide sealing against the pressurized water of the reactor.

Abstract: The clamping and locking device (18) of the clamp includes a screw (22) arranged in a direction which is transverse with respect to the articulated elements of the clamp and engaged through two blocks (19, 19') bearing on two articulated elements of the clamp, which include two guide journals (20a, 20b) each engaged and held in an opening of a bar (26a, 26b). The openings (27a, 27b; 28a, 28b) include a pair (27a, 27b) of circular openings and a pair (28a, 28b) of oblong openings. Nuts (25, 25') allow the clamp to be clamped and locked. The clamp further includes a blocking device (31) consisting of a support (33) including a strut (34) traversed by an opening and including parts (35a, 35b) for engagement on the bars (26a, 26b), a lock nut (37) rotationally mounted in the opening of the support (33), an arrangement (41) for blocking the lock nut (37) in rotation and in axial translation, and at least one blocking finger (44a, 44b) pivotably mounted on the support (33).

Abstract: The device includes a removable supporting end piece (26) which comes to rest on the top end part of a support assembly (21) fixed to the end of a port adapter of the head of the vessel of a nuclear reactor, and a pressure plate (28) including an odd number of lifting screws (31), so as to move the instrumentation column (22) upward and to clamp it against a support surface (24). A tightening assembly (35) for the lifting screws includes a tightening spindle (42a) having an end part (45) shaped to receive a tool (40) for rotating the spindle, and in turn rotates tightening spindles mounted so as to idle in the mounting plate (38) of the tightening assembly (35). The tightening spindles comprise shaped end parts (46a) coming into engagement with drive parts (31b) of the lifting screws (31) of the pressure plate (28), so as to tighten all the lifting screws simultaneously.

Abstract: The thimble (10) is introduced into a guidance duct consisting of a guidance tube (5) joining a measurement room (3) to the vessel (1) of the nuclear reactor, a vertical channel passing through the lower internals (14) of the reactor beneath the core (12) and a tube guide (17) of an assembly of the core (12). The closed end of the thimble penetrates into the tube guide of the fuel assembly as far as a defined level. The position of the thimble (10) is modified along the axis of the guidance duct, between two periods of use of the thimble in the nuclear reactor, so as to modify the position of the heavy wear zones of the wall of the thimble (10) with respect to the guidance duct. Preferably, the axial position of the thimble (10) is adjusted by using an extension of the thimble fixed to a seal (8) of the guidance duct and into which the end of the thimble is screwed.

Abstract: The ultrasonic wave sensor (2) according to the invention comes into contact with a wall at a high temperature (1) by means of a wave guide (5) made of a vitro-ceramic material. The sensor includes, inside a body (3) made of metallic material, a piezoelectric ceramic pellet (8) connected to an electrical power supply or measurement leads (9). The wave guide (5), also placed in the body (3), is in contact by one of its ends (5b) with the piezoelectric pellet (8) and by its other end (5a) with the wall (1). The body (3) of the sensor is mounted in an articulated manner on a support (21) fixed to the wall (1). The invention applies in particular to the measurement of flow rate in a primary duct of a pressurized-water nuclear reactor.