Variable Circumference Lock Insert for Nuclear Fuel Assembly Disassembly
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Solution Overview
Problem
The existing fastening structure of nuclear fuel assembly top nozzles and lock inserts makes it difficult to disassemble and reassemble, particularly due to the hydraulic uplift force and thermal expansion, which complicates maintenance and remote operation.
Innovation Solution
A lock insert with a variable circumference insertion part, including first and second latching members and insertion members, that can be easily inserted into and separated from the guide hole of the flow channel plate, allowing for adjustable size to facilitate disassembly and reassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lock tube is inserted into the top nozzle insert to prevent release, then coupling reliability is improved, but disassembly difficulty increases
Solution Approach 1:
The lock tube is divided into a lock insert and a lock tube, where the lock insert remains in the top nozzle insert and the lock tube can be separately removed. This segmentation allows the coupling to maintain reliability through the lock insert while enabling easy disassembly by removing only the lock tube portion.
Solution Approach 2:
The locking function is extracted from a single integrated lock tube and separated into two components: the lock insert that provides continuous coupling reliability and the lock tube that can be independently removed for disassembly. This extraction resolves the contradiction by allowing the reliable locking function to persist while enabling easy separation.
2Stability of the object's composition
If the top nozzle insert and lock tube are firmly coupled, then structural stability is improved, but remote operation difficulty increases
Solution Approach 1:
The coupling system is segmented into fixed components (top nozzle insert with lock insert) and removable components (lock tube). This allows structural stability to be maintained through the fixed lock insert while enabling remote operation by designing the lock tube for easy extraction through dedicated removal mechanisms.
Solution Approach 2:
The lock tube acts as an intermediary element that can be inserted to provide firm coupling for structural stability, yet can be independently removed to enable remote operation. The separation of the lock tube from the lock insert allows it to serve as a removable mediator that facilitates both stable coupling and easy disassembly.
3Reliability
If multiple parts are used for fastening, then coupling reliability is improved, but device complexity increases
Solution Approach 1:
The fastening system is segmented into minimal essential components: the lock insert that provides anchoring reliability and the lock tube that provides coupling stability. This segmentation achieves reliable fastening with fewer parts compared to traditional multi-component locking mechanisms, thereby reducing device complexity while maintaining coupling reliability.
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
Simplifies the disassembly and reassembly process, reduces the number of parts, and enhances handleability for remote maintenance and repair of nuclear fuel assemblies.
Implementation Method 1
a circumference of the insertion part may be variable in size, thereby being capable of being inserted into the guide hole
Data Source
AI summary
System for separating and coupling a nuclear fuel assembly from/to a top nozzle which has a flow channel plate with guide holes. The system includes a lock insert and a separation member. The lock insert includes an insertion part provided on a top portion of a hollow body. The separation member is configured to separate the insertion part from a guide hole. The insertion part is variable in size. The insertion part comprises a first latching member and a second latching member, each having a step which contacts the flow channel plate. The first latching member includes a latching groove which is inserted into a member protruding from the top surface of the flow channel plate. The second latching member contacts a bottom surface of the flow channel plate. The separation member provides a space accommodating an outer circumferential surface of the first latching member.