Nuclear Control Rod Unlatching Tool With Worm Drive

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Solution Overview

Problem

Current methods for unlatching control rod blades in nuclear reactors are cumbersome and require direct access to the D-handle, which can be challenging due to the complex geometry and heavy equipment involved.

Innovation Solution

An unlatching tool comprising a baseplate, guide members, A-frames, a stepper motor, worm drive, cable reel, and a treble hook with foldable fingers, which allows for precise positioning and engagement with the control rod D-handle using hydraulic fluid and a rotary union, enabling efficient unlatching without direct manual access.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If direct manual access to the D-handle is used for unlatching, then the operation is simple, but it requires complex geometry navigation and heavy equipment handling that reduces safety and efficiency

Engineering Contradiction:
Improveunlatching operationVSAvoidsafety
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent introduces an unlatching tool as an intermediary device between the operator and the control rod D-handle. This tool includes a baseplate with guide members that navigate the complex geometry, a worm drive mechanism for controlled rotation, and a hook with foldable fingers that engage the D-handle. The intermediary tool eliminates the need for direct manual access while maintaining operational simplicity and improving safety through remote operation capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces direct manual mechanical operation with a automated mechanical system. The worm drive mechanism converts rotational motion from the cable reel into controlled rotation of the D-handle, while the foldable fingers provide automated engagement and disengagement. This mechanical substitution allows for more precise control and reduces the physical burden on operators.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If remote operation is implemented, then safety is improved, but device complexity increases

Engineering Contradiction:
ImprovesafetyVSAvoidunlatching tool
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The unlatching tool is segmented into distinct functional modules: a baseplate with guide members for positioning, a worm drive mechanism for rotation control, a cable reel for actuation, and a hook with foldable fingers for engagement. Each module performs a specific function and can be independently analyzed or maintained. This segmentation manages complexity by breaking down the overall system into manageable components with clear interfaces.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The baseplate serves multiple functions: it provides a stable mounting platform, incorporates guide members for navigation through complex geometry, and supports the worm drive mechanism. The hook structure also serves dual purposes by providing both engagement with the D-handle and a means for attachment to the cable reel. This multi-functionality reduces the number of separate components needed, thereby managing overall device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

The tool facilitates safe and efficient unlatching of control rod blades by allowing remote operation and precise engagement with the D-handle, reducing manual labor and improving safety by minimizing direct interaction with heavy equipment.

Implementation Method 1

a worm drive attached to the first frame, a cable reel shaft attached to the worm drive

Methodology Applied
Scientific EffectWorm drive: Worm Drive

Implementation Method 2

using hydraulic fluid and a rotary union

Methodology Applied
Scientific EffectHydraulic fluid: Hydraulic Press

Data Source

PatentEP2453442B1Control rod blade unlatching tool
Publication Date: 2015.10.21 GE HITACHI NUCLEAR ENERGY AMERICAS LLC
  • EP2453442B1 patent drawingFigure 1
  • EP2453442B1 patent drawingFigure 2
  • EP2453442B1 patent drawingFigure 3

AI summary

Disclosed is an unlatching tool (100) that may be used to unlatch a control rod from a control drive. The unlatching tool may include a baseplate (110), a first guide member (120) and a second guide member (125) attached to the baseplate (110), a first frame (140A) and a second frame (140B) attached to the baseplate (110), a stepper motor (155) attached to the first frame (140A), a worm drive (150) attached to the first frame (140A), a cable reel shaft (400) attached to the first and second frame (140A,140B), a hose (200) wrapped around the cable reel shaft (400), and a hook (180) attached to a first end of the hose (200). The hook (180) may include a cylindrical sleeve (182) having at least one finger (184,185,186) configured to fold and unfold. Disclosed also is a method of unlatching a control rod from a control drive.