Steam Generator Tube Cutting for Stable In-Place Dismantling
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Solution Overview
Problem
The existing methods for dismantling steam generators, particularly those with numerous heating tubes, are inefficient and costly due to the complexity of handling and cutting through the outer shell, which can damage the static stability and result in cumbersome components during removal.
Innovation Solution
A method involving a cutting cable is inserted through openings in the steam generator shell to encircle and sever the heating tubes without cutting through the outer shell, allowing for controlled cutting and removal without compromising the static stability, enabling the steam generator to be dismantled in the installation position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the outer shell and internal fittings are dismantled in one cut using a wire saw, then the dismantling process is simplified, but the heating pipes become cumbersome and difficult to handle individually
Solution Approach 1:
The invention segments the heating pipes from the steam generator by cutting only the heating pipes while leaving the outer shell intact. This allows the heating pipes to be separated into individual manageable components while the shell remains as a stable structure, resolving the contradiction between simplified dismantling and ease of handling.
2Ease of operation
If the steam generator is cut through to remove heating pipes, then the heating pipes can be removed, but the static stability of the shell is damaged
Solution Approach 1:
The invention extracts only the heating pipes from the steam generator system by cutting them individually or in bundles, while deliberately leaving the outer shell uncut and intact. This extraction approach allows heating pipe removal while preserving the static stability of the shell structure.
3Ease of operation
If the heating pipes are cut and pulled out through the support grid, then the heating pipes can be removed, but bending of the pipes occurs making removal difficult
Solution Approach 1:
The invention performs preliminary cutting of the heating pipes above the tube sheet before attempting removal. This preliminary action severing the pipes at an optimal location prevents bending during the removal process through the support grid, making extraction straightforward.
4Reliability
If the steam generator is dismantled as a unit at another location, then radioactively contaminated components can be separated, but the expansion becomes very complex and expensive
Solution Approach 1:
The invention segments the heating pipes from the shell in situ, creating separable components that can be independently handled for radioactive contamination management. This segmentation achieves reliable separation of contaminated components while avoiding the complexity of complete unit dismantling at another location.
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
This approach allows for the efficient and cost-effective dismantling of steam generators by cutting through heating tubes inside the unit, preserving the static stability of the shell and facilitating the removal of long heating pipes without bending, thus saving time and resources.
Implementation Method 1
the cutting cable is pulled inwards during cutting and gradually cuts through the heating pipes
Implementation Method 2
By guiding the cutting cable within the gap, i.e. between the inner surface of the jacket and the virtual envelope of the heating pipes, the cutting cable is pulled inwards during cutting and gradually cuts through the heating pipes
Data Source
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AI summary
The invention relates to a method for dismantling a steam generator (10) or parts thereof, which has a plurality of heating tubes (24, 26, 28) extending from a lower tube sheet (18), the entire enclosure of which is surrounded by a steam generator jacket (12) at a distance, wherein the heating tubes are cut off above the floor and then removed from the steam generator. The following process steps are carried out for cutting: Inserting a cutting rope into the interior of the steam generator (10) through a first opening extending above the tube sheet (18) and encircling all tubes with the cutting rope, leading the cutting rope out of the steam generator through the first opening (42), connecting the cutting rope to a drive device and cutting the heating tubes and pulling the cut heating tubes out of the steam generator.