Fuel Assembly Bottom Nozzle Debris Grid with Streamlined Ligaments
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Solution Overview
Problem
Existing nuclear fuel assemblies face challenges in efficiently filtering debris while maintaining optimal coolant flow and minimizing pressure losses, which can affect mechanical integrity and heat exchange efficiency.
Innovation Solution
A debris filtering grid is positioned upstream or downstream the tie plate of a nuclear fuel assembly's bottom nozzle, featuring streamlined ligaments and flow channels to enhance debris filtration and straighten fluid flow, reducing turbulence and pressure losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a debris filtering grid is installed to filter debris, then debris filtering capability is improved, but pressure losses increase
Solution Approach 1:
The patent applies streamlined ligaments with curved, aerodynamic profiles instead of straight rigid bars. This curvature design reduces flow separation and turbulence downstream of the ligaments, thereby minimizing pressure losses while maintaining effective debris filtering capability across the flow channels.
Solution Approach 2:
The patent varies the spacing, dimensions, and arrangement of the ligaments to optimize the balance between filtering effectiveness and flow resistance. By adjusting these geometric parameters, the grid achieves adequate debris retention while minimizing the pressure drop across the structure.
2Reliability
If ligaments are added to filter debris, then debris filtering is improved, but fluid flow control deteriorates due to turbulence
Solution Approach 1:
The streamlined, curved profile of the ligaments is specifically designed to guide fluid flow smoothly around and behind each ligament. This reduces flow separation and downstream turbulence, maintaining more uniform fluid flow distribution across the fuel assembly while preserving debris filtering effectiveness.
3Reliability
If a debris filtering grid is installed, then debris filtering capability is improved, but device complexity increases
Solution Approach 1:
The ligaments in the filtering grid serve multiple functions simultaneously: they act as debris barriers, flow straighteners, and turbulence reducers. This multi-functionality allows a single structural element to address multiple requirements, reducing the need for additional separate components and simplifying the overall device design.
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 solution provides enhanced debris filtering capabilities with reduced pressure losses, improving coolant flow uniformity and mechanical integrity by minimizing turbulence and pressure drops.
Implementation Method 1
at least a part of the ligaments being streamlined such as to exhibit a streamlined profile and straighten the fluid flow downstream and/or upstream the debris filtering grid
Data Source
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AI summary
The debris filtering grid is configured to be positioned upstream or downstream a tie plate (16) of a bottom nozzle of a nuclear fuel assembly, the tie plate (16) having structural members (20) and flow passages (22) delimited between the structural members (20), wherein the debris filtering grid comprises flow channels (36) for a coolant fluid to flow through the debris filtering grid and ligaments (40) extending across the flow channels (36) for filtering debris, at least a part of the ligaments (40) being streamlined such as to exhibit a streamlined profile and straighten the fluid flow downstream and/or upstream the debris filtering grid.