Underwater Support Pin Replacing Device for Nuclear Control Rods
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Solution Overview
Problem
Existing support pin replacing apparatuses for control rod cluster guide tubes in nuclear reactors cannot perform operations underwater and lack automation for pin replacement, leading to increased radiation exposure and longer operational times for operators.
Innovation Solution
A support pin replacing apparatus that includes a submerged frame, a movement device, a retrieval manipulator, a supply manipulator, a rotating mechanism for loosening/tightening fastenings, and a control device to automate the replacement of support pins underwater, utilizing electrical discharge machining for unfastening and rotating tools to facilitate the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If support pin replacement is performed manually in gas environment, then operators can perform the replacement, but operators are exposed to radiation and operational time is extended
Solution Approach 1:
The patent replaces manual mechanical operations with an automated robotic system that performs support pin replacement underwater. The manipulator system with automated tools (electrical discharge machining tool, rotating tool, tightening tool) eliminates the need for operators to work in radiation-prone gas environments, thereby reducing radiation exposure while maintaining operational capability.
Solution Approach 2:
The patent utilizes the underwater environment as an inert/shielding atmosphere to protect operators from radiation. By performing the support pin replacement underwater rather than in air/gas environment, the water acts as a radiation shield, allowing automated operations to proceed without exposing operators to harmful radiation levels.
2Productivity
If support pin replacement is performed manually, then the process can be completed, but operational time is extended
Solution Approach 1:
The patent implements a self-service automated system where the manipulator performs all support pin replacement operations autonomously underwater. The system includes automated fastening removal via electrical discharge machining, automated rotation of the support pin, and automated tightening of the new support pin, eliminating manual intervention and significantly reducing operational time.
Solution Approach 2:
The patent enables continuous automated operation by maintaining the manipulator and tools in an underwater environment, allowing uninterrupted support pin replacement without the need to exit the water for tool changes or operator shifts. The system continuously performs fastening removal, pin rotation, and tightening operations in sequence, maximizing productivity and minimizing total operational time.
3Extent of automation
If automation is implemented for support pin replacement, then radiation exposure is reduced, but device complexity increases
Solution Approach 1:
The patent employs a multi-functional manipulator system that can perform multiple operations (fastening removal, support pin rotation, new support pin tightening) using different tools attached to the same manipulator. This universal system reduces the need for multiple separate complex devices, as one manipulator handles all replacement tasks by tool attachment/detachment, thereby managing device complexity while achieving full automation.
Solution Approach 2:
The patent introduces a control system as an intermediary that coordinates the complex automated operations. The control system manages the manipulator movements, tool selection and attachment, electrical discharge machining parameters, rotation control, and tightening force application, thereby simplifying the overall system architecture by centralizing control logic and reducing the complexity burden on individual components.
4Stability of the object's composition
If control rod cluster guide tube is held stably, then posture is constant, but movement control complexity increases
Solution Approach 1:
The patent applies localized holding forces at specific points on the control rod cluster guide tube using the manipulator. By gripping the guide tube at predetermined positions with the manipulator's end effector, the system maintains stable posture locally while allowing controlled movement for the replacement operations. This localized approach avoids the need for complex global positioning systems.
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
Enables automated support pin replacement underwater, reducing radiation exposure and shortening operational times by stabilizing the control rod cluster guide tube posture and optimizing tool replacement procedures.
Implementation Method 1
the unfastening means is an electrical discharge machining tool, and the fixed fastening between the nut and the support pin main body is unfastened by electrical discharge machining of the electrical discharge machining tool
Data Source
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AI summary
There is provided a support pin replacing apparatus for a control rod cluster guide tube that allows automation of replacement of a support pin in an underwater environment. The support pin replacing apparatus for a control rod cluster guide tube includes a frame submerged in water, a movement device that holds the control rod cluster guide tube and moves the control rod cluster guide tube along the frame, a retrieval manipulator that retrieves a support pin of the control rod cluster guide tube under the water, a supply manipulator that supplies a new support pin to the control rod cluster guide tube under the water, a rotating means that imparts rotation for loosening or tightening a fastening between a nut of the support pin or the new support pin and the support pin main body, and a control device that calculates variation in distance between the nut and the support pin main body on the basis of the rotation, and controls the control rod cluster guide tube to move along the frame in accordance with the variation in distance calculated by the movement device.