Miniature Sludge Lance for Steam Generator Tube Cleaning
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Solution Overview
Problem
Conventional cleaning methods for steam generators are ineffective in accessing and removing sludge from the narrow gaps between tubes due to physical restrictions and limitations in accessing the tube bundle, leading to incomplete cleaning and increased radiation exposure for technicians.
Innovation Solution
A miniature sludge lance system that can pass through narrow tube gaps, featuring a nozzle assembly with lateral nozzles for efficient cleaning and a segmented rail for precise alignment and oscillation, allowing for automated and efficient cleaning through inspection ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional cleaning methods are used, then technicians can access the tube lane area, but they cannot effectively clean the narrow gaps between tubes due to physical restrictions
Solution Approach 1:
The cleaning system is divided into multiple segments including a segmented rail system that can be inserted through inspection ports and extended into the tube bundle. The nozzle assembly is also segmented with multiple nozzles positioned at different locations to clean different areas, allowing the system to navigate narrow gaps between tubes that conventional single-piece equipment cannot access
Solution Approach 2:
The invention transitions from conventional lateral access through large tube lane openings to vertical access through inspection ports. The segmented rail system moves vertically through the inspection port and then horizontally between tubes, utilizing a two-dimensional insertion path that bypasses the physical restrictions of the tube bundle geometry
2Productivity
If conventional lancing equipment is used, then cleaning can be performed through tube lane access, but sludge remains between close pattern tubes and at locations spaced from the tube lane
Solution Approach 1:
Different nozzle assemblies are positioned at specific locations to address local cleaning needs. The segmented rail system places nozzles at various distances from the inspection port, with each nozzle targeted to clean specific tube rows or gaps. This localized approach ensures complete sludge removal in areas that conventional uniform cleaning patterns miss
Solution Approach 2:
The segmented rail acts as an intermediary mechanism that bridges the inspection port and the distant tube bundle areas. It enables the transmission of cleaning fluid and mechanical motion from the accessible inspection port location to the hard-to-reach areas between close-pattern tubes, serving as a mediator that overcomes the geometric barriers
3Reliability
If technicians perform manual cleaning, then they can address inaccessible areas, but radiation exposure increases
Solution Approach 1:
The automated segmented rail system performs cleaning operations independently without requiring technician entry into the high-radiation tube bundle area. The system self-navigates through the inspection port, self-positions the nozzles, and self-executes the cleaning function, eliminating human exposure to radiation while maintaining complete cleaning effectiveness
Solution Approach 2:
The invention replaces manual mechanical cleaning operations with an automated mechanical system. The segmented rail with oscillating nozzles provides automated sludge removal, substituting human labor with a remotely operable mechanical system that reduces radiation exposure to technicians while achieving the same or better cleaning results
4Ease of operation
If a miniature sludge lance system is used, then cleaning can be performed through inspection ports, but the system complexity increases
Solution Approach 1:
The system is divided into modular segments including the segmented rail, nozzle assemblies, and coupling mechanisms. This segmentation allows each component to be relatively simple in design while the overall system achieves the complex function of navigating through inspection ports and cleaning the tube bundle. The modular nature also facilitates maintenance and operation
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 system enables quick, accurate, and repeatable cleaning of the tube sheet and outer surfaces, reducing radiation exposure and improving cleaning efficiency by allowing high-velocity jets to be directed parallel to the tube sheet, effectively addressing the limitations of conventional methods.
Implementation Method 1
introducing a cleaning tool, or 'lance,' through the inspection penetrations that are narrower than the tube gap... structured to spray the high velocity jet generally parallel to the tube sheet
Data Source
AI summary
A miniature sludge lance for a steam generator in a pressurized water nuclear reactor is provided. The sludge lance is structured to enter the steam generator via an inspection opening and has a body sufficiently thin to fit between adjacent tubes. The sludge lance rail has at least two types of nozzle assemblies that may be attached thereto. One nozzle assembly rotates and another nozzle assembly translates in a vertical direction. A drive assembly, a mounting assembly, an oscillation assembly, and flow straighteners are also provided.