Nuclear Fuel Storage Rack Sleeve Design

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Solution Overview

Problem

Existing storage racks for nuclear fuel assemblies face challenges such as risk of rifling damage to neutron-absorbing plates during loading and unloading, complex production processes, and suboptimal mass and criticality performance due to direct contact between fuel assemblies and neutron-absorbing materials.

Innovation Solution

A storage rack design featuring sleeves with corner profiles and maintenance structures that guide fuel assemblies, preventing direct contact with neutron-absorbing plates and allowing for precise positioning, while using metallic-matrix composite materials for neutron absorption, optimizing mechanical strength, mass, and production ease.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If neutron-absorbing plates are used to ensure sub-criticality and increase storage capacity, then criticality control is improved, but the risk of rifling damage to the plates during loading and unloading operations increases

Engineering Contradiction:

Improvecriticality controlVSAvoidrifling damage risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary component (the sleeve with neutron-absorbing material) between the fuel assembly and the neutron-absorbing plates. This intermediary protects the plates from direct contact with the fuel assembly during loading and unloading operations, eliminating the rifling damage risk while maintaining the criticality control function through the sleeve's neutron-absorbing properties.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Stability of the object's composition

If serrated edges are added to neutron-absorbing plates to maintain their position, then positioning stability is improved, but manufacturing complexity and production costs increase

Engineering Contradiction:

Improveplate positioning stabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The patent extracts the positioning function from the neutron-absorbing plates themselves and transfers it to the sleeve structure. The sleeve's geometric features (such as its fit within the cell and its interaction with the rack structure) provide the necessary positioning stability, allowing the neutron-absorbing plates to have simple, flat edges that are much easier to manufacture.

Inventive Principle:

Principle #2Taking out (Extraction)

3Strength

If openwork tubes with thick walls are used to form sleeves and position neutron-absorbing plates, then structural strength is improved, but mass increases and production costs rise

Engineering Contradiction:

Improvesleeve structural strengthVSAvoidsleeve mass

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The patent employs composite construction by integrating the neutron-absorbing material directly into the sleeve structure, creating a composite component that combines structural support and neutron absorption functions. This eliminates the need for separate thick-walled tubes and standalone neutron-absorbing plates, reducing overall mass while maintaining strength through optimized material distribution and structural design.

Inventive Principle:

Principle #40Composite materials

4Reliability

If continuous neutron-absorbing plates are used in sleeves, then criticality control is improved, but manufacturing complexity and assembly difficulty increase

Engineering Contradiction:

Improvecriticality controlVSAvoidsleeve production complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the neutron-absorbing material into discrete plates positioned within the sleeve structure. This segmentation simplifies manufacturing by allowing standard cutting and shaping operations on individual plates rather than creating complex continuous structures. The segmented plates are easily assembled into the sleeve, reducing overall assembly complexity while maintaining effective criticality control through proper positioning and spacing.

Inventive Principle:

Principle #1Segmentation

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 enhances mechanical strength, reduces mass, simplifies production and assembly, minimizes rifling damage, and maintains sub-criticality by using corner profiles and maintenance structures to guide fuel assemblies, ensuring precise geometry and efficient neutron absorption.

Implementation Method 1

this sleeve has a neutron absorption power, as described in document FR 2 759 484. To do this, plates made from a so-called 'neutron absorbing' material, such as borated stainless steel, are used.

Methodology Applied

Scientific EffectNeutron absorption: Absorption (physical)

Data Source

PatentUS8848853B2Storage rack for fresh or spent nuclear fuel assemblies

Publication Date: 2014.09.30 TN INT (FR)

AI summary

A storage rack for nuclear fuel assemblies, comprising a rigid structure defining a plurality of adjacent cells, and comprising in each cell a sleeve defining a cavity intended to receive a nuclear fuel assembly, the sleeve having, in cross-sectional orthogonal to the longitudinal direction, a generally polygonal shape whereof the sides are produced using plates made from a neutron-absorbing material. According to the invention, the sleeve also includes: profiles each forming a corner piece, arranged on at least several angles of the generally polygonal cross-section, these profiles serving as a mounting bracket for the plates made of a neutron-absorbing material; and a structure for maintaining the profiles therebetween.