Steam Generator Tube Cutting with Expandable Internal Saw
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Solution Overview
Problem
Conventional methods for cutting steam generator tubes in nuclear power plants are inefficient, generating secondary contamination substances like dust and aerosols, and require the steam generator to be separated from the plant, posing risks of radioactive leakage and worker exposure.
Innovation Solution
A tube cutting device with a rotary body, clamps, and a doughnut-shaped saw is inserted into the steam generator tube, allowing for internal cutting without separating the steam generator, using a ball screw for linear movement and a conical fitting member to extend saw blades for external cutting, controlled by motors and hydraulic systems to minimize contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermal treatment is used to cut the steam generator shell in a conventional closed workplace, then the shell can be cut, but dust and aerosol as secondary contamination substances are generated
Solution Approach 1:
The patent replaces thermal treatment with a mechanical cutting system consisting of a rotary body with saw blades that rotate and extend to cut the shell. This mechanical substitution eliminates the thermal processes that generate dust and aerosols, solving the contradiction between cutting capability and contamination prevention
Solution Approach 2:
The patent performs cutting operations within the sealed steam generator shell, creating a contained environment that prevents dust and aerosols from dispersing into the surrounding area. The cutting is done in a controlled space where secondary contamination is minimized and contained
2Ease of manufacture
If the steam generator is separated from the nuclear power plant for cutting, then cutting can be performed, but the steam generator must be moved to a closed workplace which is inconvenient and time-consuming
Solution Approach 1:
Instead of moving the steam generator to a cutting facility, the patent inverts the approach by bringing the cutting device to the steam generator and performing the cutting operation in-situ at the nuclear power plant location, eliminating the need for separation and relocation
Solution Approach 2:
The cutting device is designed as a self-contained mobile unit that can perform cutting operations at the installation location without requiring specialized closed workplaces, making the cutting capability portable and adaptable to the existing plant environment
3Productivity
If a large-diameter saw is used to cut the tube from the inside, then the tube can be cut effectively, but the saw cannot be inserted into the tube due to diameter constraints
Solution Approach 1:
The saw is divided into multiple segmented blades that can be stored in a compact configuration within the rotary body. When needed, the blades extend radially outward to form the cutting perimeter, allowing the saw to fit within the tube during insertion but expand to effective cutting size during operation
Solution Approach 2:
The saw blades are designed to be dynamically extendable and retractable. During insertion, the blades are retracted to minimize the diameter. During cutting, the blades extend to the required cutting diameter, allowing the system to adapt its size based on operational requirements
4Ease of manufacture
If the steam generator tube is cut from the outer peripheral surface, then cutting can be performed, but it is hard to cut according to the structural characteristics of the steam generator
Solution Approach 1:
Instead of cutting from the outer peripheral surface, the patent inverts the approach by inserting the cutting device through the open end of the tube and performing the cutting operation from the inside, making the operation feasible given the tube's structural characteristics
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 safe and efficient cutting of steam generator tubes within the nuclear power plant, reducing secondary contamination and protecting workers from radioactive substances by performing the cutting operation internally, thus preventing dust and aerosol generation.
Implementation Method 1
a ball screw configured to allow the rotary body to be linearly driven on a horizontal axis of the rotary body
Implementation Method 2
controlled by motors and hydraulic systems to minimize contamination
Data Source
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AI summary
The exemplary embodiments relates to a tube cutting device for cutting a tube of a waste steam generator, and more particularly, to a tube cutting device that is provided with a saw (14) mounted at the interior of a small-sized tube attached to the steam generator to cut the small-sized tube at the time when the steam generator is removed from a nuclear power plant. According to the exemplary embodiments, the tube cutting device for cutting the tube of the waste steam generator is capable of conducting the cutting, while the waste steam generator is not being separated from a nuclear power plant, unlike the conventional practice, generating no dust and aerosol as secondary contamination substances therefrom, and safely protecting a worker from radioactive contamination substances not through labor force, but through mechanical work.