Search

WO-2026093121-A1 - MAINTENANCE TOOL COMPRISING A NUT RETAINER

WO2026093121A1WO 2026093121 A1WO2026093121 A1WO 2026093121A1WO-2026093121-A1

Abstract

This maintenance tool (1) comprises a carrying ring (5) and a nut retainer (7), the carrying ring (5) comprising a chamber (9) opened on one side and intended to carry a nut (11), the nut retainer (7) comprising at least one lever (13), said lever (13) being mobile between an opened position and a closed position of the chamber (9), the lever (13) being destined to support a nut (11) when being in the closed position.

Inventors

  • WILD, David

Assignees

  • Pilgrim International Ltd.

Dates

Publication Date
20260507
Application Date
20251023
Priority Date
20241030

Claims (10)

  1. 1. Maintenance tool (1) comprising a carrying ring (5) and a nut retainer (7) supported by the carrying ring, wherein the carrying ring (5) comprises a chamber (9) opened on one side and intended to carry a nut (11), and wherein the nut retainer (7) comprises at least one lever (13), said lever (13) being mobile between an opened position and a closed position of the chamber (9), the lever (13) being destined to support the nut (11) when being in the closed position.
  2. 2. Maintenance tool (1) according to claim 1, wherein said lever (13) comprises a blade (15) with a thickness between 0,5 and 4 mm, preferably between 1 and 2 mm, the blade (15) being destined to support the nut (11).
  3. 3. Maintenance tool (1) according to claim 2, wherein the blade (15) is L-shaped and comprises a recess (18) to avoid a stud (17) entering the supported nut (11) to touch said blade (15), the blade (15) sliding against the carrying ring (5) when moving between the opened position and the closed position.
  4. 4. Maintenance tool (1) according to any of the preceding claims, wherein said lever (13) comprises a cam (19), the nut retainer (7) comprising a mechanism (21) interacting with said cam (19).
  5. 5. Maintenance tool (1) according to claim 4, wherein the mechanism (21) comprises a piston (23), preferably a pneumatic piston, and a spring (25), said spring (25) exerting a force on the piston aiming to put said piston (25) in a position which aim to put the lever (13) in a closed position.
  6. 6. Maintenance tool (1) according to claim 4 or 5, wherein the nut retainer (7) comprises a pin (27) and a spring (25) for said lever (13), the pin (27) being linked to the spring (25), the pin (27) and the spring (25) exerting a force on the cam (19) of the lever (13) aiming to put said lever (13) in a closed position.
  7. 7. Maintenance tool (1) according to any of the claim 4 to 6, comprising an even number of levers (13), the nut retainer (7) comprising one mechanism (21) for two levers (13).
  8. 8. Maintenance tool (1) according to any of the claim 4 to 7, wherein the mechanism (21) is positioned inside the carrying ring (5). 2024P00080DE
  9. 9. Maintenance tool (1) according to any of the preceding claims, comprising as many levers (13) as chambers (9).
  10. 10. Maintenance tool (1) according to any of the preceding claims, wherein each lever (13) is realized in stainless steel.

Description

2024P00080DE Maintenance tool comprising a nut retainer 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. 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. Conventional approaches to servicing internal components often rely on a series of manual manipulations and the use of specialized tools to secure and adjust various fasteners. These tools operate effectively within the confined spaces of the reactor and ensure that no parts are misplaced or dropped, as such incidents could lead to significant operational disruptions and potential safety hazards. The industry has recognized the need for improved tools that enhance safety, efficiency, and precision during these maintenance operations. 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 studs that secure the CRDMs are tasks that require precise execution. Traditional methods for performing these tasks involve manual operations that are time-consuming and expose maintenance personnel to radiation for extended periods. Furthermore, the risk of dropping components such as nuts within the reactor poses a significant contamination threat. Existing solutions for CRDM maintenance involve the use of tools that require manual handling of nuts and studs, which can be 2024P00080DE 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. 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 complexity of these tools and the precision required for their operation also contribute to the overall challenge of maintaining CRDMs efficiently and safely. The present maintenance tool addresses these challenges by providing an automated solution for the carrying of nuts near studs useful for the tensioning and detensioning of said studs on CRDM assemblies. The invention relates to a maintenance tool, for example of a control rod drive mechanism of a power reactor, that comprises a carrying ring and a nut retainer supported by the carrying ring and designed to facilitate the handling of nuts during maintenance operations. The carrying ring comprises a chamber opened on one side and intended to carry a nut, and the nut retainer comprises at least one lever, said lever being mobile between an opened position and a closed position of the chamber, the lever being destined to support the nut when being in the closed position, allowing for secure and efficient maintenance operations. The tool's design ensures homogeneous and simultaneous tensioning of studs, as well as the transport and release of nuts within the tool, thereby minimizing the risk of contamination and reducing maintenance time and radiation exposure. According to one aspect of the invention, the lever compri ses a blade with a thickness between 0,5 and 4 mm, preferably between 1 and 2 mm, the blade being destined to support the nut. Advantageously, the blade is L-shaped and comprises a recess to avoid a stud entering the supported nut to touch said blade, the blade sliding against the carrying ring when moving between the opened position and the closed position. Advantageously, each lever comprises a cam, the nut retainer comprising a mechanism interacting with said cam. 2024P00080DE In one embodiment, the mechanism comprises a pi ston, preferably a pneumatic piston, and a spring, said spring exerting a force on the piston aiming to put said piston in a position which aim to put the lever in a closed position. In one particular embodiment, the nut retainer comprises a pin and a spring for each lever, the pin being linked to the spring, the pin and the spring exerting a force on the cam of the lever aiming to put said lever in a closed position. Advantageously, the maintenance tool comprises an even number of levers, the nut retainer comprising one mechanism for two levers. Advantageously, the mechanism is positioned inside the carrying ring. In one embodiment, the maintenance tool comprises as many levers as chambers. Adv