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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Optimization of Energy Absorbing Materials for Radioactive Packaging

Most applications of honeycomb materials are for lightweight structural members. This area of honeycomb material behavior has been extensively researched. In packaging design, honeycomb materials are used for impact energy absorption. Data concerning the deformation of stainless steel honeycomb structures is not widely available. It is being proposed to use honeycomb stainless steel as an impact energy absorber in a new radioactive material shipping package. Honeycomb materials can be useful for energy absorption applications because the geometry causes the structure to have a constant compressive force during buckling. This Finite Element Analysis is used to predict the compressive buckling strength of various honeycomb structures in order to design an energy absorber for a specific package weight and geometry. The model simulates a drop test where a 50 pound plate lands flat on a honeycomb stainless steel structure from a height of 30 feet. Some actual drop tests have already been performed on real specimens. Most of the resulting deformations of these tests include the bottom of the honeycomb structure buckling while the rest of the structure was either slightly deformed or straight. The deformation of the simulated honeycomb specimen matched the deformation from the actual drop tests. This is one verification that the model is working properly. It is evident that after about 2.5% strain the strength is a relatively linear value, and eventually flattens out to about 875 psi. The crush strength measured from the actual drop tests for the same density honeycomb was just over 800 psi. This is further verification that the model is working correctly. The results gathered from the FEA model successfully mirror the results from a real drop test. The deformation looks realistic, and the compressive strength found is consistent with the empirically measured value. Future work for this model includes modeling different density honeycomb structures which have not been tested before. This will allow for optimization of honeycomb stainless steel use for impact absorption in radioactive material shipping packages.

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DOE OSTI2021

Water Migration and Swelling in Engineered Barrier Materials for Radioactive Waste Disposal

Deep, underground repositories are needed to isolate radioactive waste from the biosphere. Because bentonite is an integral component of many multibarrier repository systems, information on the hydraulic behavior of bentonite is crucial for modeling the long-term viability of such systems. In this paper the hydraulic behavior of bentonite samples was analyzed as a function of aggregate size, and samples were subjected to hydrothermal treatments involving contact with NaCl, KCl, and deionized water. Neutron and X-ray imaging were used to quantify water sorption into packed bentonite samples and bentonite swelling into the water column. The distance between the original clay-water interface and the wetting front was determined as a function of time. Average water uptake exhibited a square-root-of-time dependence in freshly prepared samples, but more variable rates were observed for samples previously in contact with water. The radiography was supported by small-angle neutron scattering analysis and ultra-small-angle neutron scattering analysis of aggregate size distributions and by inelastic neutron scattering to understand the physicochemical environment of the sorbed water. Results showed that hydrothermal treatment with KCl had the greatest effect of increased water transport in the bentonite, possibly as a result of the interaction of K + with smectite layers in the clay.

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DOE OSTI2020

Determining Outgassing of Foam Packaging Material

When transporting highly radioactive material, it is vital to provide a successful delivery. Without proper containment, radioactive materials can become exposed to the surrounding environment and pose a serious threat. To ensure a safe transition of radioactive material, packaging components must be able to withstand high levels of heat during the event of a fire while maintaining the integrity of the structure to safety contain the radioactive material. Various types of polyurethane and silicone have been selected to observe at high temperatures to analyze outgassing characteristics of the materials.

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