Neutron Absorbing Apparatus Chevron Wall Structure
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Solution Overview
Problem
Nuclear fuel assemblies stored in submerged fuel racks face criticality risks due to the deterioration of neutron absorbing materials, requiring either replacement or additional neutron absorbers, and existing neutron absorbing inserts are complex and complicate fuel assembly handling.
Innovation Solution
A neutron absorbing apparatus with a chevron-shaped wall structure formed by bending a single plate of a metal matrix composite having neutron absorbing particulate reinforcement, which can be slid into fuel rack cells without removing the fuel assemblies, providing adequate neutron absorption and structural rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional neutron absorbing materials are used in fuel rack cell walls, then neutron absorption is provided, but the materials deteriorate after being submerged in water for over a decade
Solution Approach 1:
The patent employs a metal matrix composite material containing neutron-absorbing particulate reinforcement (such as boron carbide particles in an aluminum matrix). This composite structure combines the corrosion resistance and structural integrity of the metal matrix with the neutron absorption capability of the particulate reinforcement, providing both durability in submerged environments and effective neutron absorption over extended periods
Solution Approach 2:
The patent modifies the chemical composition and microstructure of the neutron absorbing material by using a composite formulation with specific particle size distributions and volume fractions of neutron-absorbing particles within the metal matrix. These parameter changes optimize both the corrosion resistance and neutron absorption cross-section, enabling long-term reliability in water-submerged conditions
2Reliability
If removable neutron absorbing inserts are used to replace deteriorating materials, then neutron absorption is maintained, but the inserts complicate fuel assembly handling procedures
Solution Approach 1:
The patent integrates the neutron absorbing function directly into the fuel rack cell wall structure through the composite material lining. This merging of the neutron absorbing function with the structural component eliminates the need for separate removable inserts, thereby simplifying fuel assembly handling procedures while maintaining continuous neutron absorption protection
Solution Approach 2:
The composite material lining is designed to be permanently integrated into the cell wall structure, providing self-sustaining neutron absorption without requiring external intervention for installation or removal. The material serves itself by maintaining its structural and functional integrity over time, eliminating the need for manual insert/removal operations during fuel assembly handling
3Duration of action of stationary object
If additional neutron absorbers are added to extend storage period, then storage duration is extended, but the device complexity increases
Solution Approach 1:
The metal matrix composite material performs multiple functions simultaneously: it provides structural support for the cell wall, resists corrosion in the water-submerged environment, and absorbs neutrons through the particulate reinforcement. This multi-functionality extends the storage period capability without requiring additional separate components, thereby avoiding increased device complexity
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 effectively extends the storage period of spent fuel assemblies by providing a durable and efficient neutron absorbing mechanism that simplifies fuel assembly handling and reduces the risk of criticality.
Implementation Method 1
a neutron absorbing apparatus with a chevron-shaped wall structure formed by bending a single plate of a metal matrix composite having neutron absorbing particulate reinforcement
Data Source
AI summary
A neutron absorbing insert for use in a fuel rack. In one aspect, the insert includes: a plate structure having a first wall and a second wall that is non-coplanar to the first wall; the first and second walls being formed by a single panel of a metal matrix composite having neutron absorbing particulate reinforcement that is bent into the non-coplanar arrangement along a crease; and a plurality of spaced-apart holes formed into the single panel along the crease prior to bending.