Movable Gripper Assembly for Nuclear Fuel Handling
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Solution Overview
Problem
Existing fuel assembly handling tools often get stuck due to interference with the top nozzle's hold down springs during alignment, causing delays in refueling operations, as they are designed with fixed gripper fingers that require precise alignment and can become locked under the springs if misaligned.
Innovation Solution
A fuel assembly handling tool with a gripper assembly that can be moved between a withdrawn and extended position using an actuator arm, allowing it to avoid contact with the top nozzle during initial alignment and ensuring the gripper fingers can fully grip the assembly without interference, featuring guide pins for precise alignment and a mechanism to lock in both positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed gripper fingers are used at a fixed elevation below the tool head, then the tool structure is simple, but the gripper fingers can become locked under the top nozzle hold down springs causing operational delays
Solution Approach 1:
The gripper fingers are made movable relative to the tool head through an actuator mechanism, allowing them to be raised to a clear position above the top nozzle components during alignment and lowered to a gripping position for fuel assembly handling. This dynamic positioning eliminates the risk of the gripper fingers becoming locked under the hold down springs while maintaining structural simplicity.
2Reliability
If the gripper fingers are lowered onto the fuel assembly for gripping, then the fuel assembly can be secured, but the gripper fingers may interfere with the top nozzle hold down springs during alignment
Solution Approach 1:
The gripper fingers are positioned in a retracted or clear position above the top nozzle during the alignment phase, allowing the tool to be positioned over the fuel assembly without interference. Once alignment is complete, the gripper fingers are actuated downward to engage the fuel assembly for secure gripping and lifting operations.
3Measurement precision
If alignment pins are used to ensure precise positioning, then the tool can be accurately aligned with the fuel assembly, but misalignment can still cause the gripper fingers to contact the hold down springs
Solution Approach 1:
The alignment pins are provided with alignment holes that guide the positioning of the tool relative to the fuel assembly before the gripper fingers are lowered. This preliminary alignment action ensures that the tool is correctly positioned over the fuel assembly, preventing the gripper fingers from contacting the hold down springs and eliminating the need for time-consuming recovery operations.
Data Source
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AI summary
A fuel assembly handling tool that can be lowered onto the top nozzle of a fuel assembly, positively latch the top nozzle, unlatch from the top nozzle, and be raised off the top nozzle of the fuel assembly. The tool head, that interfaces with the top nozzle has load bearing grippers that latch onto the fuel assembly, that are located in a storage position up within the tool while the tool is lowered onto the fuel assembly. The gripper fingers are then lowered into position during the latching process, and are raised back to the storage position during the unlatching process. In the storage position, the gripping fingers are spaced above the fuel assembly top nozzle when the tool head is resting on the nozzle.