Maintenance tool comprising an upper stage and a lower stage electrically and pneumatically connected

Abstract

This maintenance tool (1) comprises a lower stage (31) comprising a carrying ring (9) comprising electric devices (33) and pneumatic devices (35) for screwing a nut and tightening a stud, the electric and pneumatic devices (33, 35) being connected to a first set of electrical and pneumatic sockets (37), the maintenance tool (1) comprising an upper stage (39) comprising a connector (41) and a second set of electrical and pneumatic sockets (43) connected to the connector (41) and being intended to interface with the first set of electrical and pneumatic sockets (37) at the junction of the lower stage (31) and the upper stage (39).

Description

[0001] 2024P00083DE

[0002] Maintenance tool comprising an upper stage and a lower stage electrically and pneumatically connected

[0003] The present disclosure relates to nuclear reactor maintenance equipment, specifically tools for tensioning and detensioning control rod drive mechanism (CRDM) assemblies within an evolutionary power reactor.

[0004] More specifically, the present disclosure relates to the integration of electrical and pneumatic connections for sensors and actuators used for the screwing of nuts on the adapter nozzle of the control rod drive mechanism in order to ensure a correct sealing of said adapter nozzle.

[0005] Maintenance activities within nuclear reactors are complex, often requiring the shutdown of the facility and intricate maneuvers to access and service the internal components. These activities are further complicated by the need to minimize radiation exposure for personnel and the spatial constraints of the reactor's interior. Traditional methods for servicing these components involve intricate procedures that are not only time-consuming but also pose a risk of exposure to hazardous conditions.

[0006] Maintenance of control rod drive mechanisms (CRDMs) in power reactors presents a significant challenge due to the close proximity of CRDM assemblies within the reactor's closure head. The CRDM facilitates the movement of control rods, which regulate the nuclear reaction. During maintenance, the tightening and loosening of nuts and studs that secure the CRDMs are tasks that require precise and quick execution.

[0007] Existing solutions for CRDM maintenance involve the use of tools that require manual handling of nuts and studs, which can be cumbersome and inefficient. These tools often necessitate the removal of surrounding CRDM assemblies to access the target assembly, leading to increased downtime and radiation exposure. It should be noted that a reactor comprises for example between 10 and 200 CRDM. Additionally, the manual retention mechanisms used to hold the nuts in place are prone to failure, increasing the risk of losing nuts within the reactor. The 2024P00083DE complexity of these tools and the precision required for their operation also contribute to the overall challenge of maintaining CRDMs efficiently and safely.

[0008] The present maintenance tool addresses these challenges by providing an automated solution for the screwing of nuts around studs useful for the tensioning and detensioning of said studs on CRDM assemblies.

[0009] However, industrial machinery often incorporates a multitude of sensors and actuators within confined spaces. These components require reliable and easy connections for proper operation. The challenge has been to manage the complex array of connections without hindering access to maintenance functions. The task of efficiently organizing these connections, while maintaining the ease of maintenance, has been a persistent issue in the design and operation of a compact maintenance tool .

[0010] A solution that simplifies the maintenance process by allowing for quick and efficient separation of connections without compromising the integrity and functionality of the machine is highly desirable.

[0011] The invention relates to a maintenance tool, for example of a control rod drive mechanism of a power reactor, for screwing a nut around a stud protruding from a flange and for tightening said stud.

[0012] The maintenance tool comprises a lower stage comprising a carrying ring comprising electric devices and pneumatic devices for screwing said nut and tightening said stud, the electric and pneumatic devices being connected to a first set of electrical and pneumatic sockets.

[0013] The maintenance tool comprises an upper stage comprising a connector and a second set of electrical and pneumatic sockets connected to the connector and being intended to interface with the first set of electrical and pneumatic sockets at the junction of the lower stage and the upper stage.

[0014] The upper stage facilitates the connection of the electric and pneumatic devices to an external control system, while simultaneously allowing for unobstructed access to the maintenance tool's pneumatic and electric functions. The configuration with two stages also simplifies the disconnection or connection process, enabling the upper part of the 2024P00083DE tool to be separated from the lower part with ease. As a result, maintenance personnel can quickly access the components of the lower part of the maintenance tool without the need to navigate through a dense network of wires and contact connectors.

[0015] In one embodiment, the upper stage comprises a metallic ring and an annular grid protruding from the metallic ring toward the lower stage, the metallic ring supporting the connector and the annular grid supporting the second set of electrical and pneumatic sockets.

[0016] Advantageously, the upper stage comprises cables connecting the connector to the second set of electrical and pneumatic sockets, the cables being fixed against the annular grid by cable clamps.

[0017] In one embodiment, the maintenance tool comprises three metal rods protruding from the lower stage and destined to be inserted in holes, positioned through the metallic ring, the upper stage comprising screws intended to be inserted in the metal rods to solidly connect the lower stage with the upper stage.

[0018] In one aspect of the invention, the first set of electrical and pneumatic sockets and the second set of electrical and pneumatic sockets are respectively paired two by two into push-pull manual sockets.

[0019] In one embodiment, each one of the first and the second set of electrical and pneumatic sockets comprise between 30 and 60 sockets, preferably between 40 and 50 sockets, among which are between 1 and 10 pneumatic sockets, preferably between 2 and 5 pneumatic sockets.

[0020] Advantageously, the upper stage comprises two connectors, each connector compri sing at least 50 electric pins.

[0021] In one particular embodiment, each electrical socket comprises between one and five electrical wires.

[0022] Advantageously, the pneumatic devices comprise a pneumatic actuator to operate at least two j aws, and a nut retainer comprising a lever being mobile between an opened position and a closed position of a chamber of the carrying ring, the lever being destined to support the nut positioned in the chamber when being in the closed position.

[0023] In one particular embodiment, the external diameter of the lower stage and the upper stage is comprised between 200 and 400 mm, preferably between 250 and 350 mm. 2024P00083DE

[0024] The present invention and its advantages will be better understood by studying the detailed description of specific embodiments given by way of non-limiting examples and illustrated by the appended drawings on which:

[0025] Figure 1 is a schematic representation of the maintenance tool according to the invention; and

[0026] Figure 2 is a cross-sectional view of the lower stage of the maintenance tool according to the invention.

[0027] The maintenance tool 1 of a control rod drive mechanism of a power reactor is designed for screwing a nut 3 around a stud 5 protruding from a flange 7, and for tightening said stud 5, illustrated in the figure 2. A general view of the maintenance tool 1 is schematically represented in the figure 1 .

[0028] The maintenance tool 1 comprises a lower stage 3 1. The lower stage 3 1 includes a carrying ring 9, electric devices 33 and pneumatic devices 35 supported by the carrying ring 9 for screwing said nut 3 and tightening said stud 5.

[0029] The electric devices 33 comprise electric motors like the motor 20, electric sensors and electric support cylinders like the support cylinder 25.

[0030] The pneumatic devices 35 comprise a pneumatic actuator to operate at least two j aws 24, and a nut retainer comprising a lever 27 being mobile between an opened position and a closed position of a chamber 1 1 of the carrying ring 9. The j aws 24 secure the stud in order for the tensioner of said stud to apply some tension. The lever 27 i s destined to support the nut 3 positioned in the chamber 1 1 when being in the closed position.

[0031] The electric devices 33 and pneumatic devices 35 are connected to a first set of electrical and pneumatic sockets 37.

[0032] The maintenance tool 1 further comprises an upper stage 39. The upper stage 39 includes a connector 41 , for example an industrial connector, and a second set of electrical and pneumatic sockets 43 connected to the connector 41.

[0033] The second set of electrical and pneumatic sockets 43 is intended to interface with the first set of electrical and pneumatic sockets 37 at the junction of the lower stage 3 1 and the upper stage 39. 2024P00083DE

[0034] In other words, the first set of electrical and pneumatic sockets 37 and the second set of electrical and pneumatic sockets 43 are paired two by two, preferably into push-pull manual sockets, also known as push-pull manual connectors.

[0035] In one aspect of the invention, the external diameter of the lower stage 3 1 and the upper stage 39 is compri sed between 200 and 400 mm, preferably between 250 and 350 mm.

[0036] The lower stage 3 1 and the upper stage 39 are annular with an inner diameter comprised between 100 and 190mm.

[0037] The maintenance tool 1 has a height comprised between 600 and 1000 mm.

[0038] The maintenance tool 1 has a compact size and thus needs a clear organization of its connections.

[0039] Advantageously, the upper stage 39 comprises a metallic ring 45 and an annular grid 47 protruding from the metallic ring 45 toward the lower stage 3 1 .

[0040] The annular grid 47 is for example made of metal .

[0041] The metallic ring 45 supports the connector 41 , and the annular grid 47 supports the second set of electrical and pneumatic sockets 43.

[0042] The upper stage 39 comprises cables 49 connecting the connector 41 to the second set of electrical and pneumatic sockets 43.

[0043] The cables 49 are fixed against the annular grid 47 by cable clamps 51 .

[0044] The annular grid 47 has a height of at least 50 mm, ensuring enough space for the cables 49 to run against said annular grid 47 and to be fixed on it.

[0045] Each one of the first and the second set of electrical and pneumatic sockets 37, 43 comprise between 30 and 60 sockets, among which are between 1 and 10 pneumatic sockets.

[0046] The number of sockets represents roughly the number of devices in the lower stage 3 1 . In order to disconnect a device 33 or 35, electronic or pneumatic, only one socket 37, 43 is usually to be disconnected, facilitating the maintenance of the maintenance tool 1.

[0047] For example, and to be able to manage a great number of devices, the upper stage 39 comprises two connectors 41 , each connector 41 2024P00083DE comprising at least 50 electric pins. The pins can then be easily connected to a control unit.

[0048] Each electrical socket 37 or 43 comprises between one and five electrical wires, corresponding to the pins of the connector 41. Indeed, an electrical device 33 needs for example two wires for the electrical supply and sometimes one or more wire to transfer some data, for example with an electronic sensor.

[0049] The maintenance tool 1 further comprises three rigid metal rods 53 protruding from the lower stage 3 1 and destined to be inserted in holes 55 positioned through the metallic ring 45.

[0050] The upper stage 39 comprises screws 57 intended to be inserted in the metal rods 53 , the head of the screws 57 relying on the metallic ring, to solidly connect the lower stage 3 1 with the upper stage 39.

[0051] Thus, to remove the upper stage 39 from the lower stage 3 1 , the screws 57 must be removed, along with all the sockets 37, 43 , leaving the lower stage 3 1 clear without too many cables obstructing the visibility.

[0052] As previously described, the maintenance tool 1 comprises a carrying ring 9 which includes a chamber 1 1 with an opening 13 on one side. The chamber 1 1 is designed to house the nut 3 during the maintenance operation, as illustrated in figure 2.

[0053] In one particular embodiment, the maintenance tool 1 comprises more than two chambers 1 1 , for example ten chambers 1 1 , housing as many nuts 3 to be screwed on as many studs 5 of the flange 7. Preferably, all nuts 3 are to be screwed all together on the same time.

[0054] A gear socket 15 is positioned in the chamber 1 1 and is intended to fit the shape of the nut 3 carried in the chamber 1 1. For example, the nut is a hexagonal nut, the gear socket 15 thus has an inner hexagonal section designed to fit said nut 3. When a nut 3 is inserted in the gear socket 15, they are considered as solidly connected to each other, due in particular to the force of the spring 23 described below.

[0055] The gear socket 15 is mobile along a rotational movement on itself and a translation toward the opening 13. In other words, the gear socket 15 is mobile along a helical movement facilitating the engagement and disengagement of the nut 3 with the stud 5. 2024P00083DE

[0056] A helical movement is the sum of a rotational movement and of a translation. Here, the translation and the rotational movement are not linked into a fixed helical movement, they are two distinct movements. A helical movement for screwing can be obtained when adding the rotational movement and the translation, but a pure translation is also possible in order to reset the stroke of the gear socket and increase the total stroke on which a nut can be screwed.

[0057] The gear socket 15 also comprises an external thread 17, which interacts with a drive sprocket 19, more particularly which rotates on itself under the influence of the drive sprocket 19. For example, each the gear socket 15 and the drive sprocket 19 have teeth that are respectively engaged to ensure the rotation, and also forming grooves allowing a transversal movement along said grooves, the gear socket 15 being able to slide in translation against the drive sprocket 19.

[0058] The translation is favored by the tapping and thread of the nut 3 and the stud 5, the screwing of the nut 3 around the stud 5 forcing the nut 3 and the gear socket 15 to translate toward the opening 13.

[0059] The maintenance tool 1 comprises a motor 20, linked to the drive sprocket 19 with a mechanical gear 22. The motor 20 drives the drive sprocket 19 so that the gear socket 15 rotates on itself, enabling the screwing or unscrewing of the nut 3.

[0060] The motor 20 is an electric motor, providing the necessary power and control for the precise movement of the gear socket 15. It may present also an advantage for its compacity, the maintenance tool 1 being used in a constrained environment.

[0061] An abutment ring 21 forms the opening 13 of the chamber 1 1. The abutment ring 21 is positioned on the way of the gear socket 15 so that said abutment ring 21 prevents the gear socket 15 from dropping when there is no nut 3 in the carrying ring 9. The abutment ring 21 also prevents the gear socket 15 from disengaging with the drive sprocket 19.

[0062] In other words, the gear sockets 15 is mobile in translation compared to the drive sprocket 19. However, the gear sockets 15 is always engaged with said drive sprocket 19 and the abutment ring ensures that the gear socket 15 remains engaged during the maintenance operation, providing stability and reliability. 2024P00083DE

[0063] A spring 23 is positioned in the chamber 1 1 , exerting a force on the gear socket 15 and / or the nut 3 aiming to push said nut 3 out of the chamber 1 1 toward the opening 13. This feature assists in the engagement of the nut 3 with the stud 5 and ensures that the nut 3 is readily available for screwing onto the stud 5. The spring 23 also helps to initiate the translation movement of the gear socket 15 and nut 3.

[0064] The maintenance tool 1 also comprises a support cylinder 25 protruding from the carrying ring 9 toward the flange 7 on which it takes support. The support cylinder 25 is destined to fix a distance between said carrying ring 9 and the flange 7. The support cylinder 25 is an electric support cylinder, providing precise control over the distance maintained between the carrying ring 9 and the flange 7 during the maintenance operation. For example, the maintenance tool 1 comprises three support cylinders 25 in order to have an isostatic support between the carrying ring and the flange.

[0065] A lever 27 is included in the maintenance tool 1 , being mobile between an opened position and a closed position of the chamber 1 1. The lever 27 is destined to support the nut 3 when being in the closed position, ensuring that the nut 3 is securely held in place during the maintenance process and especially when the nut 3 is carried near the stud 5.

[0066] The carrying ring 9 comprises at least two chambers 1 1 and gear sockets 15 , allowing for the simultaneous screwing of multiple studs 5 and nuts 3. This feature significantly enhances the efficiency of the maintenance operation by allowing multiple nuts 3 to be screwed or unscrewed concurrently.

[0067] Also, the simultaneous screwing of all nuts 3 is preferably wanted, in order to bring the carrying ring 9 and the flange 7 closer, by reducing the length of the support cylinders 25 simultaneously.

[0068] Additionally, the maintenance tool 1 comprises a position sensor destined to measure the axial position of the gear socket 15 and the nut 3. More precisely, the position sensor monitors the nut 3 altitude in regard to the flange 7, via a measure on the gear socket 15.

[0069] The maintenance tool 1 may also comprise a distance sensor monitoring the carrying ring altitude in regard to the flange 7. 2024P00083DE

[0070] A great number of position or distance sensors are present into the maintenance tool 1 when said maintenance tool 1 comprises a great number of chambers 1 1 , for example, at least 20 electrical sensors for 10 chambers 1 1 .

Claims

2024P00083DECLAIMS1. Maintenance tool ( 1 ) for screwing a nut (3 ) around a stud (5) protruding from a flange (7) and for tightening said stud (5), the maintenance tool ( 1 ) comprising a lower stage (3 1 ) comprising a carrying ring (9) comprising electric devices (33) and pneumatic devices (35) for screwing said nut (3) and tightening said stud (5), the electric and pneumatic devices (33 , 35) being connected to a first set of electrical and pneumatic sockets (37), the maintenance tool ( 1 ) comprising an upper stage (39) comprising a connector (41 ) and a second set of electrical and pneumatic sockets (43) connected to the connector (41 ) and being intended to interface with the first set of electrical and pneumatic sockets (37) at the junction of the lower stage (3 1 ) and the upper stage (39).

2. Maintenance tool ( 1 ) according to claim 1 , wherein the upper stage (39) comprises a metallic ring (45) and an annular grid (47) protruding from the metallic ring (45) toward the lower stage (3 1 ), the metallic ring (45) supporting the connector (41 ) and the annular grid (47) supporting the second set of electrical and pneumatic sockets (43).

3. Maintenance tool ( 1 ) according to claim 2, wherein the upper stage (39) comprises cables (49) connecting the connector (41 ) to the second set of electrical and pneumatic sockets (43), the cables (49) being fixed against the annular grid (47) by cable clamps (51 ).

4. Maintenance tool ( 1 ) according to any of the claims 2 and 3 , comprising three metal rods (53) protruding from the lower stage (3 1 ) and destined to be inserted in holes (55) positioned through the metallic ring (45), the upper stage (39) comprising screws (57) intended to be inserted in the metal rods (53) to solidly connect the lower stage (3 1 ) with the upper stage (39).

5. Maintenance tool ( 1 ) according to any of the preceding claims, wherein the first set of electrical and pneumatic sockets (37) and the second set of electrical and pneumatic sockets (43) are respectively paired two by two into push-pull manual sockets.

6. Maintenance tool ( 1 ) according to any of the preceding claims, wherein each one of the first and the second set of electrical and pneumatic sockets (37, 43) comprise between 30 and 60 sockets,2024P00083DE preferably between 40 and 50 sockets, among which are between 1 and 10 pneumatic sockets, preferably between 2 and 5 pneumatic sockets.

7. Maintenance tool ( 1 ) according to any of the preceding claims, wherein the upper stage (39) comprises two connectors (41 ), each connector (41 ) comprising at least 50 electric pins.

8. Maintenance tool ( 1 ) according to any of the preceding claims, wherein each electrical socket comprises between one and five electrical wires.

9. Maintenance tool ( 1 ) according to any of the preceding claims, wherein the pneumatic devices (35) comprise an actuator to operate at least two j aws (24), and a nut retainer comprising a lever (27) being mobile between an opened position and a closed position of a chamber ( 1 1 ) of the carrying ring (9), the lever (27) being destined to support the nut (3) positioned in the chamber ( 1 1 ) when being in the closed position.

10. Maintenance tool ( 1 ) according to any of the preceding claims, wherein the external diameter of the lower stage (3 1 ) and the upper stage (39) is comprised between 200 and 400 mm, preferably between 250 and 350 mm.

Images