Response of Energetic Materials to Thermal Hazards
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While recognized standards exist for the systematic safety analysis of potential spills or releases from LNG (Liquefied Natural Gas) storage terminals and facilities on land, no equivalent set of standards or guidance exists for the evaluation of the safety or consequences from LNG spills over water. Heightened security awareness and energy surety issues have increased industry's and the public's attention to these activities. The report reviews several existing studies of LNG spills with respect to their assumptions, inputs, models, and experimental data. Based on this review and further analysis, the report provides guidance on the appropriateness of models, assumptions, and risk management to address public safety and property relative to a potential LNG spill over water.
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Scalable thermal runaway models for cook-off of energetic materials (EMs) require realistic temperature- and pressure-dependent chemical reaction rates. The Sandia Instrumented Thermal Ignition apparatus was developed to provide in situ small-scale test data that address this model requirement. Spatially and temporally resolved internal temperature measurements have provided new insight into the energetic reactions occurring in PBX 9501, LX-10-2, and PBXN-109. The data have shown previously postulated reaction steps to be incorrect and suggest previously unknown reaction steps. Model adjustments based on these data have resulted in better predictions at a range of scales.
We report progress of a continuing effort to characterize and simulate the response of energetic materials (EMs), primarily HMX-based, under conditions leading to cookoff. Our experiments include mechanical-effects testing of HMX and FIMX with binder at temperatures nearing decomposition thresholds. Additional experiments have focused on decomposition of these EMs under confinement, measuring evolution of gas products and observing the effect of pressurization on the solid. Real-time measurements on HMX show abrupt changes that maybe due to sudden void collapse under increasing load. Postmortem examination shows significant internal damage to the pellets, including voids and cracks. These experiments have been used to help develop a constitutive model for pure HMX. Unconfined uniaxial compression tests were performed on HMX and LX-14 to examine the effect of binders on the deviatoric strength of EM pellets, and to assess the need of including deviatoric terms in the model. A scale-up experiment will be described that is being developed to validate the model and provide additional diagnostics.