BWR Feedwater Sparger Pin Clamp Wear Reduction
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Solution Overview
Problem
Feedwater sparger end brackets in boiling water reactors experience wear due to flow-induced vibration, leading to axial misalignment and increased maintenance needs.
Innovation Solution
A clamp assembly is installed on the feedwater sparger end bracket pin, increasing the bearing area of the pin head and distributing the load over a larger surface area, thereby reducing wear and restoring the original alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pin head bearing area is increased to reduce wear, then the load distribution improves, but the device complexity increases due to additional clamp components
Solution Approach 1:
The clamp assembly is divided into separate functional components: a clamp body that contacts the pin head, a bolt for applying clamping force, and a washer for load distribution. This segmentation allows each component to be optimized independently while collectively solving the wear problem through increased bearing area.
Solution Approach 2:
The clamp assembly acts as an intermediary device between the pin head and the bracket, introducing additional contact surfaces (clamp body and washer) that distribute the load. This mediator approach increases the bearing area without modifying the original pin or bracket, thereby reducing wear while maintaining structural integrity.
2Reliability
If the pin head is removed and replaced, then the wear damage is eliminated, but the loss of time occurs during removal and reinstallation
Solution Approach 1:
The clamp assembly is pre-assembled with the bolt and washer before installation on the pin head. This preliminary preparation allows for quick installation without complex assembly procedures during maintenance, reducing the time loss while restoring component integrity through the added bearing surfaces.
Solution Approach 2:
Instead of removing and discarding the worn pin head, the clamp assembly recovers the functional integrity by adding bearing surfaces around the existing pin head. This approach preserves the original pin while compensating for wear, eliminating the need for time-consuming removal and reinstallation of the pin itself.
3Manufacturing precision
If the clamp bolt is tightened to secure the clamp, then the pin head position is restored, but the friction and potential damage to the pin head increases
Solution Approach 1:
The clamp body and washer are designed with specific contact surface qualities that distribute the clamping force locally across the pin head. The washer provides a larger contact area with reduced pressure, while the clamp body contacts the top surface of the pin head. This local quality differentiation allows secure positioning without concentrating excessive stress on any single point of the pin head.
Solution Approach 2:
The washer acts as a cushioning element between the bolt and the pin head, distributing the clamping force over a larger area before it reaches the pin head. This beforehand cushioning prevents excessive localized stress and potential damage while still achieving the necessary alignment precision through the clamping action.
Data Source
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AI summary
A clamp for a boiling water reactor feedwater sparger is disclosed and claimed. The clamp assembly includes a base and cooperating bolt, a reaction arm, and a cross pin. With the exception of the cross pin, the parts are pre-assembled and then installed over the sparger pin head. The cross pin is then installed through the clamp base and through the sparger pin. The clamp bolt is then tightened, locking the clamp and sparger pin. The clamp provides an increased surface area that extends 360° around the sparger pin. This increased surface area reduces the likelihood of wear of the clamp or bracket during plant operation, and the clamp restores the position of the sparger pin head relative to the contact surface of the end bracket if the original pin head or bracket is worn.