Slip Joint Clamp With Radial Preload for BWR Jet Pump Leakage
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Solution Overview
Problem
Nuclear boiling water reactor (BWR) jet pump slip joints experience leakage due to flow-induced vibration (FIV) and misalignment issues, leading to fluid coolant leakage between the inlet mixer and diffuser interfaces, especially in worn or damaged conditions.
Innovation Solution
A flow-restricted slip joint clamp with an O-ring extension that can be biased laterally to pre-load against the inlet mixer, limiting fluid flow and securing the slip joint without axial loading of the diffuser, using nuclear-reactor-friendly materials to prevent fouling and seizing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional slip joint interface is used between inlet mixer and diffuser, then the structure is simple and easy to manufacture, but leakage occurs due to FIV and misalignment
Solution Approach 1:
The clamp assembly is nested around the slip joint interface, with the clamp body surrounding both the inlet mixer and diffuser. The O-ring extension is nested within the clamp interior, creating a layered sealing structure that addresses leakage without requiring complete disassembly of the slip joint components
Solution Approach 2:
The O-ring extension acts as an intermediary sealing element between the clamp and the slip joint interface. This intermediary component provides the actual sealing function, allowing the clamp to reliably seal the interface while maintaining structural simplicity
2Stability of the object's composition
If axial loading is applied to secure the slip joint, then the connection is stabilized, but the diffuser experiences unwanted axial loads
Solution Approach 1:
The invention transitions from axial loading to lateral (radial) loading by positioning the clamp around the slip joint interface. The biasing mechanism applies force in the radial direction through the O-ring extension, stabilizing the interface without transmitting axial loads to the diffuser
Solution Approach 2:
The clamp applies localized lateral pressure specifically at the slip joint interface through the O-ring extension, providing stability where needed while avoiding transmission of forces to other components. The force application is localized to the radial direction at the interface region
3Reliability
If the clamp is tightened to seal the slip joint, then leakage is reduced, but access for tightening becomes difficult
Solution Approach 1:
The biasing mechanism is extracted and positioned within the clamp body, with its adjustment features accessible through openings in the clamp exterior. This allows the sealing function to be maintained while providing external access for tightening and adjustment operations
4Reliability
If nuclear-reactor-friendly materials are used to prevent fouling and seizing, then reliability in nuclear environment is improved, but material selection and manufacturing become more complex
Solution Approach 1:
The material properties are changed to be compatible with nuclear reactor environments, selecting materials with appropriate radiation resistance, corrosion resistance, and thermal properties. This parameter change ensures reliability in the nuclear environment while the design maintains manufacturing feasibility through standard fabrication processes
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
Effectively reduces leakage and prevents FIV by securely sealing the slip joint interface, even in damaged or worn conditions, without requiring disassembly of the slip joint components and maintaining operational integrity in nuclear reactor environments.
Implementation Method 1
A biasing mechanism laterally moves the plunger to bias the O-ring extension against the inlet mixer
Implementation Method 2
limiting fluid flow past the same
Data Source
AI summary
Clamps can be secured to a slip joint and limit flow through the same by seating on a diffuser axially regardless of wear and damage in the slip joint. An extension from the clamp seats to the inlet mixer. These extensions can be adjusted from outside the clamp to achieve an individual preload or flow limitation through the slip joint. The extension may be an O-ring or other shape. A biasing drive may connect to and move the extension from an outside surface of the clamp. The biasing drive may include a threaded cap in an outer groove that is linked to a plunger via a spring. Clamps are fabricated of materials that maintain their physical properties when exposed to an operating nuclear reactor environment and may be relatively rigid and resilient metals.