Deformable Collar Core Screw for Reactor Maintenance
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Solution Overview
Problem
Conventional reactor pressure vessel designs face challenges in repairing or replacing core enclosing screws due to their inaccessibility when the reactor is operational, especially under thermal and radiation loads, making post-processing methods like welding and grinding inefficient and difficult.
Innovation Solution
A secure installation and replacement method using a core enclosing screw with a screw shank and hexagonal screw head, featuring a deformable screw head collar that engages with a locking plate's recesses to prevent twisting, allowing for torque-controlled installation and mechanical deformation for secure fixation, thereby avoiding costly post-processing like welding and grinding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional welding and grinding methods are used to secure core enclosing screws, then the screws are fixed against twisting and loosening, but the repair process becomes complex and time-consuming when the reactor is operational
Solution Approach 1:
The patent replaces the welding process (thermal/chemical method) with a purely mechanical deformation method. The collar is mechanically deformed into the recesses of the locking plate to secure the screw, eliminating the need for welding and subsequent grinding operations. This substitution simplifies the repair process while maintaining fixation reliability.
Solution Approach 2:
The collar's own material deformability is utilized to achieve the securing function. By applying mechanical force, the collar deforms itself to engage with the locking plate's recesses, creating a self-securing mechanism that eliminates the need for additional welding materials or complex multi-step processes.
2Reliability
If welding and grinding are performed on core enclosing screws under operational conditions, then the screws can be secured, but the operational downtime and maintenance difficulty increase significantly
Solution Approach 1:
The patent replaces the time-consuming welding and grinding sequence with a single mechanical deformation operation. The collar is deformed into the locking plate's recesses using simple mechanical force, which can be performed quickly without the extended processing time required for welding, cooling, and grinding operations.
Solution Approach 2:
The collar is designed as a sacrificial component that undergoes permanent deformation to achieve the securing function. This disposable-like approach with the collar eliminates the need for complex, time-consuming welding procedures, allowing for quick replacement and securing operations during maintenance.
3Reliability
If core enclosing screws are secured by welding, then they are fixed against loosening, but the resulting weld seams require grinding to avoid protrusions
Solution Approach 1:
The patent replaces the welding process with mechanical deformation of the collar into the locking plate's recesses. This eliminates the creation of weld seams that would require subsequent grinding, as the mechanical deformation process naturally produces a flush surface without protruding material.
Solution Approach 2:
The patent extracts the problematic welding step from the securing process entirely. By using purely mechanical deformation of the collar, the method removes the source of weld seam protrusions, eliminating the need for the additional grinding operation to achieve a flush surface.
4Ease of repair
If core enclosing screws are replaced in operational reactors, then damaged components can be replaced, but the inaccessibility and difficult conditions make the process inefficient
Solution Approach 1:
The patent replaces complex welding operations with simple mechanical deformation that can be performed using basic hand or power tools. This substitution makes the replacement process feasible under the constrained accessibility conditions of operational reactor maintenance, where complex welding equipment and procedures would be difficult to implement.
Solution Approach 2:
The collar is designed as a simple, replaceable component that can be quickly deformed and secured without requiring complex equipment. This approach enables efficient replacement of damaged screws even in the difficult accessibility conditions of operational reactor maintenance, where time and equipment availability are limited.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method simplifies the repair and replacement of core enclosing screws by ensuring secure fixation without the need for welding and grinding, facilitating easier maintenance and reducing operational downtime.
Implementation Method 1
wherein the at least one projection is designed to engage with the at least one recess after mechanical deformation to mechanically secure the core enclosing screw against rotation
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
Core enclosing screw (20), arrangement and method for the secure installation and/or replacement of core enclosing screws (4, 20) for mounting core enclosing plates (5) with at least one core enclosing screw (20) and at least one locking plate (40), wherein the core enclosing screw (20) has a screw head (24) with at least one forming (28) that at least partially surrounds the screw head (24) and the locking plate (40) has at least one internal recess (42) for receiving the screw head (24) with at least one first recess (44), in particular a hole, for the core enclosing screw (20) to pass through and at least one further recess (46) for the engagement of the screw head forming (28) to mechanically secure the core enclosing screw (20) against rotation, and the forming (28) is mechanically deformed after installation and/or replacement of the core enclosing screw (4, 20).that it engages at least partially in at least one further recess (46) of the locking plate (40), thereby securing the screw (20) against rotation or loosening.