Abstract: Device for checking clearance between the periphery of the upper core plate and the inner surface of the core enclosure of a pressurized water nuclear reactor comprising a vertical supporting structure (7) resting on the upper plate (3), a plurality of articulated assemblies (10), each carrying a calibrated feeler blade of a specified thickness, a pivoting assembly associated with each of the articulated assemblies, for moving the blades (9) in a substantially vertical direction towards the gap between the plate (3) and the enclosure (1, 2), or in the opposite direction, as well as a video camera (14) in the vicinity of the blades (9). The device enables the checking to be carried out under water and by remote control.

Abstract: Device for checking the vertical alignment of the upper and lower internal equipment of a pressurized water nuclear reactor comprising a vertical tubular body (14) onto which are fixed a flange (15) for centering the upper internal equipment on the upper plate (2), a flange (16) for centering on the upper core plate (3) and a lower end member (17) which enables the device (1) to be centered on the lower core plate (4). A metal wire (24) is aligned along the axis of the tubular body (14), its lower part being fixed to the end member (17) and its upper part to a fitting (20) which can move in two horizontal directions at 90.degree.. Electrodes are arranged in the flange (16) around the wire (24), to detect, by virtue of an electrical monitoring circuit (90), contact between the wire (24) and the electrodes when the upper part of the wire is moved by the fitting (20).

Abstract: With the reactor vessel (1) open and filled with water, and the core assemblies removed, means for measuring alignment (50) and means for measuring clearances (56, 58, 59) are mounted on the upper internal equipment (13). The upper equipment (13) is introduced into the vessel and is deposited on the lower equipment (3). Measurements of alignment are carried out and, if appropriate, the alignment is corrected by moving the upper internal equipment on the lower equipment (8). The clearances of the upper core plate are measured and, if appropriate, the upper internal equipment (13) is moved as a function of these measurements. The clearances around the centering and alignment pins are measured and adapters are machined and then fixed to the upper internal equipment (13) to reduce the clearances around the pins to a low, predetermined value. The invention also relates to the device for measuring and adapting the position of the internal equipment.

Abstract: Device for measuring clearance around a pin for centering the upper internal equipment of a pressurized water nuclear reactor comprising a carrier (b) fixed integrally to a pedestal (7) which makes it possible to fix on the upper plate of the reactor core (1) two travellers (15) which are parallel to the plate (1), two slides mounted to move on the travellers, resilient means (22) for returning the slides and a marking assembly carried by the carrier. Each slide comprises a sensing finger (30) projecting downwards relative to the bearing face of the pedestal (7) and a planar marking plate (31). The marking assembly comprises two styli (33), each directed towards a marking plate (31). A control system (34) makes it possible to compress springs (36) whose force is applied to the styli (33). The clearance measurement can be carried out from a distance and under water.