Thermal Sleeve With Intermeshed Protrusions For Nuclear Reactor Control Rods
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Solution Overview
Problem
Conventional thermal sleeves for control rod drive mechanisms in nuclear reactors suffer from inadequate thermal protection, rigidity, and fatigue resistance due to wear from vibrations, leading to potential failure and requiring complex replacement procedures.
Innovation Solution
A thermal sleeve design featuring a tube with radially extending protrusions that intermesh to form a continuous collar with an outer diameter greater than the tube, providing enhanced thermal protection and rigidity, along with a method for replacing damaged sleeves by inserting and securing the new sleeve through a nozzle with a flared support surface, using crimping or welding for fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional thermal sleeve is used, then the replacement procedure is simple, but the thermal protection, rigidity and fatigue resistance are insufficient
Solution Approach 1:
The thermal sleeve is divided into a tube and multiple separate protrusions that can be inserted and fixed independently. Each protrusion can be installed separately through the tube wall, allowing for simplified replacement procedures while creating a complex intermeshed collar structure that provides enhanced thermal protection and rigidity
Solution Approach 2:
The thermal sleeve combines the tube structure with multiple protrusions made of the same or different materials to create a composite structure. The intermeshed collar formed by the protrusions provides superior thermal protection and fatigue resistance compared to a simple tube, while maintaining a relatively simple overall design
2Strength
If the protrusions are in assembled configuration, then the rigidity and thermal protection are improved, but the insertion through the nozzle is difficult
Solution Approach 1:
The protrusions are designed to be movable relative to the tube, transitioning from a separated configuration during insertion to an assembled intermeshed collar configuration after installation. This dynamic reconfiguration allows the sleeve to be inserted in a compact form and then locked into its final rigid structure within the nozzle
Solution Approach 2:
The protrusions are designed to nest within or alongside each other during the insertion process, allowing them to pass through the nozzle in a compact separated configuration. Once inside the nozzle, they expand outward to form the intermeshed collar structure, effectively nesting the assembly process within the insertion operation
3Reliability
If the protrusions are fixed to the tube, then the fatigue resistance is improved, but the replacement complexity increases
Solution Approach 1:
The fixation mechanism is extracted as a separate functional element, with protrusions that can be independently fixed to the tube through simple methods such as crimping or welding. This separation allows the fixation process to be performed as a straightforward final step during replacement, ensuring fatigue resistance without significantly increasing overall complexity
Solution Approach 2:
The fixation method can be selected based on specific application requirements, changing parameters such as the degree of permanent attachment (crimping vs. welding). This flexibility allows optimization of fatigue resistance while controlling the complexity of the fixation process according to the specific operational needs
Data Source
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AI summary
The invention concerns a thermal sleeve (60) for a control rod drive mechanism of a nuclear reactor pressure vessel (10). The thermal sleeve (60) comprises : - a tube (62) comprising an upper end (68) and a lower end (70); and - a plurality of protrusions (64) fixed at the upper end (68) of the tube (62), each protrusion (64) extending radially outward the tube (62), the protrusions (64) being different from the tube (62), the protrusions (64) being intermeshed to form a continuous collar (80) presenting an outer diameter greater than the outer diameter of the tube (62).