BWR Riser Pipe Reinforcement Using Collar and Clamp Assemblies
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Solution Overview
Problem
BWR jet pump riser pipes are prone to cracking due to system vibration and pressure fluctuations, requiring costly repairs or replacements, and existing reinforcement methods are inadequate for providing both hoop and axial strength reinforcement effectively.
Innovation Solution
A collar assembly and clamp assembly system that provides axial and hoop strength reinforcement to the riser pipe, attached directly to the riser brace, which includes upper and lower collar assemblies and clamp assemblies to compress the riser pipe and reinforce welds, offering comprehensive reinforcement and repair capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional reinforcement methods are used, then some strength reinforcement is provided, but both hoop and axial strength reinforcement cannot be effectively provided simultaneously
Solution Approach 1:
The reinforcement system is divided into two distinct functional components: a collar assembly that provides axial compression and a clamp assembly that provides hoop strength. This segmentation allows each component to specialize in providing one type of strength reinforcement, thereby effectively addressing both axial and hoop strength requirements simultaneously without interfering with each other's function.
Solution Approach 2:
The collar assembly and clamp assembly are combined into an integrated repair system that works together to provide comprehensive reinforcement. The collar assembly compresses the riser pipe axially while the clamp assembly reinforces hoop strength, and their combined effect achieves both axial and hoop strength reinforcement that neither component could achieve alone.
2Reliability
If the riser pipe is left unreinforced, then the system operates without additional components, but cracking occurs due to system vibration and pressure fluctuations
Solution Approach 1:
The collar and clamp assemblies are installed on the riser pipe before cracking occurs or early in the repair process, applying compressive forces and reinforcement in advance to prevent crack propagation. This preliminary action stabilizes the pipe structure proactively, preventing the harmful effects of vibration and pressure fluctuations from causing further damage.
Solution Approach 2:
The collar assembly applies axial compression to the riser pipe in advance, creating a cushioning effect that absorbs and mitigates the impact of pressure fluctuations and vibrations. This beforehand cushioning protects the pipe structure from the harmful dynamic loads that would otherwise cause cracking and failure.
3Reliability
If costly repair or replacement is performed, then damaged sections are replaced, but repair costs and downtime increase
Solution Approach 1:
The damaged or weakened sections of the riser pipe are reinforced in place using the collar and clamp assemblies, extracting the reinforcement function from the pipe itself and applying it as a separate external system. This allows the pipe to be strengthened without removing or replacing the damaged sections, significantly reducing repair time and downtime while maintaining structural integrity.
Solution Approach 2:
The collar and clamp assemblies serve as external reinforcement components that can be installed relatively quickly and provide sufficient strength restoration without requiring expensive pipe replacement. These reinforcement components act as a cost-effective alternative to full pipe replacement, achieving the necessary reliability improvement with minimal downtime and lower overall cost.
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 effectively reinforces the riser pipe, reducing the likelihood of cracking and extending the lifespan of the riser pipe by providing robust axial and hoop strength, thus reducing repair costs and downtime.
Implementation Method 1
a collar assembly may function as a riser brace bracket that provides axial strength to compress the riser pipe in a lengthwise direction
Implementation Method 2
a clamp assembly may offer hoop strength to reinforce the riser pipe and resist forces exerted on the pipe in a radial direction
Data Source
Figure 1
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Figure 3
AI summary
A method and apparatus for repairing and/or reinforcing a Boiling Water Reactor (BWR) jet pump riser pipe (1). The repair (20) includes attaching two collars (20a1, 20a1', 20b1, 20b1') to the riser pipe using match drilling to drill holes through the collars and the riser pipe and plugging the holes with expandable plugs (40). Support columns (20a4, 20a4', 20a5, 20a5', 20b4, 20b4', 20b5, 20b5') are attached to the collars. Brace supports (20a2, 20a2', 20a3, 20a3', 20b2, 20b2') are slideably attached to the support columns. Gaps (G) between each brace support and its respective collar are then narrowed as ratchet bolts (50a, 50a1, 50b, 50b1) may apply a force that pulls downward on an upper collar and pulls upward on a lower collar, thereby exerting a compression force on the riser pipe. A clamp assembly (30) may also be located between the two collars that applies a hoop force on the riser pipe.