Patent Number: 047048018
Section: claims

1. Device for checking the vertical alignment of the upper internal equipment and of the lower internal equipment of a pressurized water nuclear reactor, these equipments being placed in the reactor vessel which is open and filled with water, the upper internal equipment comprising an upper plate (2) supporting the upper part of the guide tubes of the reactor, and a lower plate (3) which forms the upper core plate supporting the lower part of the guide tubes, and the lower internal equipment comprising the lower core plate (4) supporting the fuel assemblies, and the checking of alignment of the equipment being carried out with the fuel assemblies and at least some of the guide tubes in the upper internal equipment removed, which device comprises: (a) a vertical tubular body (14) on which are fixed a first flange (15), at its upper end, provided with means (26) enabling it to be centered on a guide tube position on the upper plate (2) of the upper internal equipment, a lower end member (17) for centering at its other end, and a second, intermediate flange (16) equipped with means (52, 53) enabling it to be centered on a guide tube position on the upper core plate (3);  (b) means for receiving (65) the lower end member (17), fixed on the lower core plate (4), for placing said lower end member (17) in the center of an assembly bottom fitting, in the region of the lower core plate (4);  (c) a metal wire (24) placed substantially along the axis of the tubular support (14) and along its entire length, the lower end of which is fixed to the lower end of the end member (17) and the upper end of which is fixed to a fitting (20) which can move in at least two directions at 90.degree. in the horizontal plane;  (d) means for determining accurately the movements of the movable fitting;  (e) four electrodes fixed to the intermediate flange (16) whose ends are arranged on two horizontal axes at 90.degree. around the axis of the guide tube position on which the intermediate flange (16) is placed; and  (f) an electrical monitoring circuit (59, 90) which makes it possible to detect when the wire comes into successive contact with the four electrodes (60) when its upper end is moved by means of the movable fitting (20) in the direction of each of the electrodes (60) in succession. 2. Checking device according to claim 1, wherein the tubular body (14) comprises an upper part (14a) connected at its upper end to said first flange (15) and at its lower end to said second flange (16), and a lower part (14b) connected at its upper end to said second flange (16) and at its lower end to the end member (17). 3. Checking device according to claim 2, wherein the upper tubular part (14a) and the lower tubular part (14b) are connected to said first and second flanges (15, 16) by means of devices (29, 50, 51) which permit the tubular casing (14) to be adapted by inclining the parts (14a and 14b) relative to the theoretical axis of said first and second flanges (15, 16). 4. Checking device according to claim 1, wherein four electrodes (47) are arranged inside the upper flange (15), around the wire (24), along two horizontal directions at 90.degree., said electrodes being connected to the monitoring circuit (90) to determine the initial position of the upper end of the wire (24). 5. Checking device according to claim 1, wherein the movable fitting (20) consists of two tables (40, 41) having a ball bearing traveller (42) and placed horizontally and at 90.degree. to each other, and two micrometer screws (44) each associated with the movable member of a table (40, 41). 6. Checking device according to claim 1, wherein the upper end of the wire is connected to a gantry (22) fixed to the upper flange (15) through the intermediary of a device (39) for adjusting the tension of the wire. 7. Checking device according to claim 1, wherein the end member (17) comprises a diaphragm (69) whose transverse position in the end member can be adjusted by means of screws (72), carrying a wire guide (74) through which the wire (24) passes.