Expandable Pipe Plug Assembly for BWR Jet Pump Vibration Mitigation
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Solution Overview
Problem
Conventional methods for securing a collar or bracket to the riser pipe in a Boiling Water Reactor (BWR) jet pump assembly often result in vibration and leakage due to misalignment and lack of radial forces, especially in flooded environments, and alternative methods like tapered holes are prone to weak connections and deformation.
Innovation Solution
An expandable pipe plug assembly with an angled pipe plug that acts as a wedge to expand bushing sections, providing a tight fit and minimizing leakage by matching the outer diameter of the pipe plug assembly with the inner diameter of the collar and riser pipe holes, using a thin shape and slight angle to ensure precise tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional plugs are used to secure the collar or bracket to the riser pipe, then the installation process is simple, but misalignment occurs between the plug outer surfaces and the holes, causing vibration and leakage
Solution Approach 1:
The plug is divided into multiple bushing sections that can be independently positioned and adjusted. Each bushing section contains alignment features that guide proper positioning within the holes, allowing the segments to self-align while maintaining installation simplicity.
Solution Approach 2:
Alignment features such as keys, keyways, or tapered surfaces act as intermediaries between the plug and the holes. These intermediary elements facilitate precise alignment during insertion, ensuring the plug outer surfaces align correctly with the holes to prevent vibration and leakage.
2Ease of operation
If conventional plugs are used to secure the collar or bracket to the riser pipe, then the installation process is straightforward, but radial forces are insufficient to ensure a tight fit, resulting in leakage
Solution Approach 1:
The plug transitions from a static component to a dynamic one that expands radially after installation. The expansion mechanism is activated after the plug is inserted, allowing the bushing sections to expand and create a tight fit against the holes, ensuring sealing performance without complicating the initial installation process.
Solution Approach 2:
The radial dimension of the plug is changed after insertion through expansion. This parameter change allows the plug to adapt to the hole dimensions and create a tight fit, generating sufficient radial forces to prevent leakage while maintaining installation straightforwardness.
3Force
If tapered holes with tapered plugs are used to secure the collar or bracket, then radial pressure is improved, but tight tolerances cannot be guaranteed due to EDM burn control issues, resulting in weak connections and deformation
Solution Approach 1:
The plug is segmented into multiple bushing sections that can be precisely manufactured with tight tolerances. Each segment can be independently machined to exact specifications, avoiding the cumulative tolerance issues of tapered configurations while still providing radial pressure through expansion.
Solution Approach 2:
Instead of relying on tapered geometry to generate radial pressure, the invention uses a cylindrical configuration that expands radially after insertion. This changes the mechanism from geometric taper to active expansion, allowing tight tolerances to be maintained during manufacturing while still achieving the necessary radial pressure for a strong connection.
4Reliability
If the pipe plug assembly expands bushing sections to provide a tight fit, then leakage is minimized, but the device complexity increases
Solution Approach 1:
The expansion mechanism is nested within the bushing sections themselves. The expansion components are integrated into the bushing structure, eliminating the need for separate external expansion devices. This nesting approach provides effective leakage prevention while minimizing the increase in overall device complexity.
Solution Approach 2:
The plug assembly performs its own expansion function without requiring external actuators or complex control systems. The expansion mechanism is self-contained and activates automatically or through simple operation, providing reliable leakage prevention while keeping the device complexity manageable through self-sufficiency.
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 expandable pipe plug assembly effectively mitigates vibration and leakage by ensuring a tight fit between components, even in flooded environments, and allows for secure attachment of a collar or bracket to the riser pipe, enhancing the reliability of riser pipe repairs.
Implementation Method 1
an angled pipe plug that acts as a wedge to expand bushing sections to press the bushing sections against an inside diameter of a hole
Data Source
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AI summary
A method and apparatus for securely fastening a pipe collar or a bracket to a riser pipe (51) of a boiling water reactor (BWR) jet pump assembly (50). A pipe plug assembly (1) includes an angled pipe plug (14) that acts as a wedge to expand a bushing assembly (16) as the pipe plug (14) is drawn into the overall pipe plug assembly (1). Expansion of the bushing assembly (16) allows a tight tolerance to exist between an outer diameter of the pipe plug (14) and an inner diameter of the collar / bracket and riser pipe (51). Expansion of the bushing assembly (16) allows a straight hole to be match drilled into the collar / bracket and riser pipe (51), thereby avoiding a more complicated tapered hole to be drilled into the collar / bracket and riser pipe (51). An ensuing tight fit between the pipe plug assembly (1), the collar / bracket and the riser pipe (51) mitigates vibration of components and minimizes leakage to acceptable levels for use in the flooded environment of the annulus region where the jet pump assembly (50) exists in the BWR.