Radioactive Material Package Shock Absorber with Deforming Tubes
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Solution Overview
Problem
Existing packaging solutions for radioactive materials face challenges in effectively managing the forces generated during axial drops, which can lead to damaging impacts on the closure system, and there is a need for improved internal dampers that offer a better compromise in terms of size, cost, and performance.
Innovation Solution
The packaging incorporates an internal shock absorber featuring a single or multiple layers of plastic deformation damping tubes, arranged orthogonally to the packaging's longitudinal axis, with specific dimensions and spacing to maximize energy absorption and minimize interactions between tubes during deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If metal foam damping devices are used to absorb shock during axial drops, then the energy absorption capacity is improved, but the device complexity and cost increase
Solution Approach 1:
The damping device is segmented into multiple layers of tubes arranged in parallel, where each layer contains multiple identical or different tube sections. This segmentation allows the complex energy absorption function to be distributed across simple, repeatable modular units, reducing overall device complexity while maintaining high energy absorption capacity through the cumulative effect of multiple tubes deforming simultaneously
Solution Approach 2:
The invention uses simple, commercially available tube sections that are easily manufactured and replaced. These tubes are designed to undergo plastic deformation during drop events and can be economically replaced if needed, avoiding the need for expensive, complex metal foam structures. The tubes serve their shock absorption purpose in a single use event and can be disposed of or replaced without significant cost
2Loss of energy
If the number of damping tubes is increased to improve energy absorption, then the energy absorption capacity increases, but the volume of the damper increases
Solution Approach 1:
The damping tubes are arranged in a compact cylindrical configuration where multiple tubes are nested concentrically around a central axis. This nesting arrangement allows a large number of tubes to be packed into a minimal volume, maximizing the energy absorption capacity per unit volume by utilizing the radial space efficiently without significant increase in overall damper dimensions
Solution Approach 2:
Instead of arranging tubes in a single plane which would increase the surface area, the invention stacks multiple layers of tubes in the axial dimension, creating a three-dimensional cylindrical structure. This dimensional transition allows the damping capacity to scale with volume rather than surface area, enabling high energy absorption in a compact form factor
3Loss of energy
If damping tubes are placed closer together to increase damping density, then the energy absorption per volume improves, but tube interactions during deformation increase
Solution Approach 1:
The invention optimizes the local spacing between adjacent tubes within each layer, ensuring that the transverse distance is sufficient to prevent interaction during radial deformation while maintaining high packing density. This local quality control ensures that each tube deforms independently and uniformly under load, preventing stress concentration and deformation anomalies that would occur if tubes were too closely spaced
4Reliability
If the transverse spacing between tubes is increased to prevent tube interactions, then the deformation uniformity is improved, but the damper volume increases
Solution Approach 1:
The tube spacing is pre-calculated and optimized during the design phase to provide the minimum necessary clearance for independent deformation. The tubes are arranged with precise transverse spacing that anticipates the deformation envelope of each tube during shock absorption, ensuring that interactions are prevented while minimizing the overall volume occupied by the damping structure
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
This design provides a compact, cost-effective, and high-performance damping solution that ensures homogeneous crushing stress, reduces the need for complex qualification processes, and prevents tube interactions during deformation, thereby enhancing the safety and efficiency of radioactive material packaging.
Implementation Method 1
an internal shock absorber housed in the containment enclosure and intended to be arranged axially between the removable cover and the set of radioactive materials. Each layer is arranged in a layer plane orthogonal to the longitudinal central axis of the packaging, the damping tubes all having, within the same layer, an annular or substantially annular section
Data Source
Figure 1
Figure 2~2A
Figure 2B
AI summary
The invention relates to a package for transporting and/or storing a set of radioactive materials, comprising an internal shock-absorber (22) housed in the containment chamber and having one or more layers (C1) of tubes (30) for absorbing shocks by plastic deformation, the tubes having an annular or substantially annular cross-section. The number and dimensions of the tubes are such that, in an axial view of the package, the ratio of the cumulative projected area of all the tubes (30) in the layer to the surface area defined by the notional circle (Cf1) of smallest diameter in which all these tubes are circumscribed is greater than 0.2. In addition, a minimum transverse spacing (Emin) is provided between the tubes of a single layer C1.