Hexagonal Fuel Rack With Adjustable Pedestals
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Solution Overview
Problem
Current fuel racks and storage casks for spent nuclear fuel face challenges in efficiently containing neutron and gamma radiation, managing residual heat, and facilitating safe transportation and storage, particularly due to size and weight constraints that complicate handling and movement.
Innovation Solution
The development of fuel racks with hexagonal tubes and adjustable pedestals for optimal neutron flux trapping, and dual-walled storage canisters with continuous surface contact for enhanced radiation containment, along with a low-profile transporter for casks to navigate through narrow spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fuel assemblies are stored in a compact arrangement to maximize space utilization, then storage density is improved, but neutron radiation containment becomes insufficient due to reduced spacing between assemblies
Solution Approach 1:
Neutron-absorbing materials (such as boron-containing materials or cadmium sheets) are introduced as intermediary substances between fuel assemblies. These materials act as mediators that absorb excess neutrons, allowing fuel assemblies to be stored in closer proximity while maintaining radiation containment safety.
Solution Approach 2:
The storage rack structure implements local quality enhancement by placing neutron-absorbing materials specifically in regions where neutron flux is highest (between adjacent fuel assemblies), rather than uniformly throughout the entire storage structure. This localized approach optimizes neutron containment while minimizing impact on storage density.
2Object-affected harmful factors
If storage casks are designed with thick radiation shielding to effectively contain neutron and gamma radiation, then radiation containment is improved, but weight increases making handling and transportation difficult
Solution Approach 1:
The storage cask employs composite material construction, combining different materials with complementary properties. For example, using high-strength steel for structural support, concrete or polyethylene for neutron shielding, and lead or depleted uranium for gamma radiation shielding. This composite approach achieves effective radiation containment while optimizing weight compared to using a single heavy material throughout.
Solution Approach 2:
The cask design applies local quality by varying the thickness and material composition of shielding layers in different regions. Thicker shielding is provided in areas with higher radiation exposure (near fuel assemblies), while thinner sections are used in areas with lower radiation levels, reducing overall weight while maintaining effective radiation containment.
3Area of stationary object
If storage facilities are designed with narrow passages for efficient space utilization, then space efficiency is improved, but mobility of heavy casks is reduced
Solution Approach 1:
The storage system is segmented into modular components: standardized casks that can be manufactured off-site and assembled in a coordinated manner within the facility. This segmentation allows for optimized passage design that accommodates the modular units while maintaining space efficiency, as the standardized sizes enable tight but manageable arrangements.
Solution Approach 2:
Mechanical assistance devices (such as remote-controlled cranes, automated handling systems, or robotic manipulators) are introduced as intermediaries to move heavy casks. These intermediary systems enable the movement of extremely heavy, well-shielded casks through narrow passages without requiring the casks themselves to be lightweight or the passages to be excessively wide.
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
These solutions effectively contain radiation, manage heat, and facilitate safe and efficient transportation and storage of spent nuclear fuel by optimizing neutron flux trapping, radiation shielding, and cask handling, addressing size and weight limitations.
Implementation Method 1
the tubes connected to the top surface of the base plate in a substantially vertical orientation and spaced from one another so that a flux trap space exists between all adjacent hexagonal tubes
Implementation Method 2
dual-walled storage canisters with continuous surface contact for enhanced radiation containment
Data Source
AI summary
A fuel rack comprises a base plate and vertically-extending hexagonal tubes. Each tube defines a cell. A top surface of the base plate forms a floor of each cell. Adjustable height pedestals can be connected to a bottom surface of the base plate. Each pedestal includes a tool engagement portion in a top surface of a peg. Rotation of the peg causes pedestal height adjustment. Each peg is aligned with a hole in a cell floor. A tool can extend through the hole to adjust the height of the pedestal. Vertically elongated spacing rods are positioned in gaps between adjacent hexagonal tubes to maintain the gaps. Each spacing rod is plug welded to a corner edge of three adjacent hexagonal tubes at a juncture via holes located in the corner edges of each of the three adjacent hexagonal tubes.