Bottom Nozzle Gridded Water Passage for Nuclear Reactor

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional nuclear reactor fuel assembly bottom nozzles experience significant water pressure drops due to obstructed water flow, which can lead to reactor accidents, as the flow holes are not sufficient to handle the weight of spacer grids and high-speed coolant flow effectively.

Innovation Solution

A bottom nozzle design featuring a hollow skirt with equidistantly configured transverse and longitudinal blades forming a three-dimensional gridded water passage system, reducing resistance and enhancing filter capacity by allowing smooth water flow and trapping foreign substances, while maintaining structural integrity under high loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If multiple flow holes are provided in the conventional bottom nozzle skirt, then the filter capacity is improved, but the water pressure drop increases due to obstructed water flow

Engineering Contradiction:

Improvefilter capacityVSAvoidwater pressure drop

Core Design Contradiction:

Quantity of substanceVSLoss of energy

Solution Approach 1:

The patent transitions from a two-dimensional array of flow holes to a three-dimensional gridded water passage system formed by intersecting transverse and longitudinal blades. This dimensional change creates multiple flow paths through the nozzle while maintaining structural integrity, allowing water to flow through the grid intersections without the obstruction problems of conventional hole-based designs

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The bottom nozzle is segmented into transverse blades and longitudinal blades that form a grid structure. This segmentation creates multiple discrete water passages while distributing the structural load, enabling both filtering functionality and reduced flow resistance simultaneously

Inventive Principle:

Principle #1Segmentation

2Strength

If predetermined spacing is formed among flow holes to maintain skirt strength, then the structural integrity is improved, but the water flow is obstructed and pressure drop increases

Engineering Contradiction:

Improveskirt strengthVSAvoidwater pressure drop

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The design moves from planar flow holes to a three-dimensional gridded passage system where water flows through spaces between intersecting blades. This allows the skirt to maintain strength through the blade grid structure while providing unobstructed water flow paths through the grid intersections

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The blade grid structure creates a porous-like configuration where water can pass through the intersections of transverse and longitudinal blades. This porous structure provides both mechanical strength through the blade framework and adequate flow capacity through the grid openings

Inventive Principle:

Principle #31Porous materials

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 design significantly reduces water pressure drop and ensures stable operation by minimizing obstructions and enhancing the structural strength of the nozzle, thereby preventing reactor accidents and maintaining normal reactor function.

Implementation Method 1

the transverse blades are equidistantly and uniformly configured in the cavity to form a transverse thin strip layer, the longitudinal blades are equidistantly and uniformly configured in the cavity to form a longitudinal thin strip layer... forming a three-dimensional gridded water passage system, reducing resistance and enhancing filter capacity

Methodology Applied

Scientific EffectFluid flow through gridded passage:

Implementation Method 2

projections of the transverse blades and the longitudinal blades in a level plane are intersectant to form interleaved grids... enhancing filter capacity by allowing smooth water flow and trapping foreign substances

Methodology Applied

Scientific EffectPhysical filtration through grid structure: Filter (physical)

Data Source

PatentUS10418135B2Bottom nozzle and light-water reactor fuel assembly

Publication Date: 2019.09.17 CHINA NUCLEAR POWER TECH RES INST CO LTD

AI summary

A bottom nozzle includes a skirt, support blocks, transverse blades and longitudinal blades. The skirt is a hollow structure and a bottom thereof is provided with corner legs which are protruded downwards, a cavity is defined in the hollow structure, the transverse blades are configured in the cavity, the longitudinal blades are configured in the cavity, the transverse blades and longitudinal blades are firmly connected with the skirt, projections of the transverse blades and the longitudinal blades in a level plane are intersectant to form interleaved grids, and the support blocks run through and are fixed on the transverse blades and the longitudinal blades. In such a way, the bottom nozzle forms a three-dimensional gridded water passage, thereby improving the filter capacity and generating small water pressure drop.