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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

LLNL Explosives Anisotropy Research

Lawrence Livermore National Laboratory scientists and engineers led a multi-institutional team in executing a series of high explosives tests that successfully demonstrated fundamental principles of anisotropy, a possible enabler for improved weapon and munition safety. Working under snowy and frigid conditions on Idaho’s Snake River Plain, a 13-member team from LLNL carried out 52 explosives shots over four days in mid-November at the Idaho National Laboratory’s (INL) National Security Test Range (NSTR) to complete the study. The broader anisotropy (ANISO) team included high explosives handlers and volunteers from INL, Los Alamos National Laboratory, Marine Raiders from the Marine Special Operations Command and members of the U.S. Special Operations Command. The purpose of the study was to explore theoretical methods of creating anisotropic explosives — explosives that perform differently depending on the direction the detonation wave moves through the explosive — by engineering certain physical features in the charges and obtaining basic data from testing. The work is part of an overall effort by the Lab to develop anisotropic explosives that could be used in munitions to reduce the severity and lethality of an unintended detonation without sacrificing performance. The data gathered from the study will be used to design and construct follow-on experiments at LLNL’s High Explosives Applications Facility (HEAF) and validate computer models for future anisotropic assemblies.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Big Explosives Experimental Facility - BEEF

The Big Explosives Experimental Facility or BEEF is a ten acre fenced high explosive testing facility that provides data to support stockpile stewardship and other national security programs. At BEEF conventional high explosives experiments are safely conducted providing sophisticated diagnostics such as high speed optics and x-ray radiography.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Effects of Void Morphology on Detonation Initiation of PBX 9502

Accurate predictive modeling of high explosives in abnormal conditions, such as a fire, is critical to personnel safety. Modeling depends heavily on precise physical characterization of the high explosive in question. The aim of this thesis was to characterize the detonation response to shock and the microstructure at high-temperature (250°C) of PBX 9502 and use these data to attempt to model these results using a new reactive burn model called SURF (Scaled Uniform Reactive Front). In order to characterize the shock response of PBX 9502 at high-temperature a 1D gas gun experiment was designed and executed that provided shock to detonation transition data. These data were then used to do a preliminary calibration of SURF for PBX 9502 at 250°C. Small-angle neutron scattering (SANS) was employed to characterize the void morphology of PBX 9502 as a function of temperature. This was done in order to feed a modified version of SURF called physically informed - SURF (π-SURF) which uses the void size and quantity distribution data as measured by SANS along with the deflagration and detonation characteristics of a high explosive to inform the SURF model. The π-SURF model was then used to model both ambient and high-temperature PBX 9502 SDT response and the results were compared to the physically measured results. It was found that π-SURF works in ambient cases. At high-temperature, however, it was determined that not enough information is known about hot spot formation to use the π-SURF model for high-temperature scenarios.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2019

BOM: The Next Generation of High Performance Explosives

The EPA has declared phase-out of Trinitrotoluene (TNT) a priority due to toxicity concerns. LANL and the Army Research Laboratory created a melt-castable next generation high performance explosive to replace TNT. They invented bis(1,2,4-oxadiazole)bis(methylene) dinitrate, or BOM, a higher-performing, safer replacement, which is 50% more energetic than TNT. BOM is less toxic to produce and use than TNT. Unlike competitors, BOM requires no performance-enhancing additives. BOM could replace TNT in a variety of civilian and military applications. BOM has been synthesized at the multi-kilogram scale.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2014

Los Alamos Explosives Performance Key to Stockpile Stewardship

As the U.S. Nuclear Deterrent ages, one essential factor in making sure that the weapons will continue to perform as designed is understanding the fundamental properties of the high explosives that are part of a nuclear weapons system. As nuclear weapons go through life extension programs, some changes may be advantageous, particularly through the addition of what are known as "insensitive" high explosives that are much less likely to accidentally detonate than the already very safe "conventional" high explosives that are used in most weapons. At Los Alamos National Laboratory explosives research includes a wide variety of both large- and small-scale experiments that include small contained detonations, gas and powder gun firings, larger outdoor detonations, large-scale hydrodynamic tests, and at the Nevada Nuclear Security Site, underground sub-critical experiments.

42 ENGINEERING↗
DOE OSTI2023

Secure Storage: Historical Documentation of TA-08-0032, TA-11-0036, TA-22-0016, TA-22-0023, TA-22-0025, TA-22-0035, TA-37-0006, TA-37-0009, and TA-37-0020

The U.S. Department of Energy, National Nuclear Security Administration, Los Alamos Field Office (NA-LA), is pursuing the decommissioning and demolition (D&D) of facilities contaminated with high-explosives residues at the Los Alamos National Laboratory (Laboratory or LANL). This effort affects nine facilities associated with high-explosives and detonator research, development, and storage: Technical Area (TA) 8 Facility 32 (TA-08-0032), TA-11-0036, TA-22-0016, TA-22-0023, TA-22-0025, TA-22-0035, TA-37-0006, TA-37-0009, and TA-37-0020. All nine facilities proposed for D&D have been evaluated for listing in the National Register of Historic Places (NRHP) and determined eligible. NA-LA previously requested the State Historic Preservation Officer (SHPO) to concur with the NRHP-eligibility determinations of these nine properties presented in four reports: (1) TA-08-0032 was determined eligible for listing in the NRHP in the report, From Ranching to Radiography: An Assessment of Historic Buildings at Anchor West Site (TA-8), Vol. 1 (McGehee et al. 2008a). The SHPO concurred with this eligibility determination on November 26, 2008. (2) TA-11-0036 was determined eligible for listing in the NRHP in the report, ESA Division’s Five-Year Plan: Consolidation and Revitalization at Technical Areas 3, 8, 11, and 16, Vol. 1) (McGehee et al. 2003). The SHPO concurred with this eligibility assessment on June 22, 2003. (3) TA-22-0016, TA-22-0023, TA-22-0025, and TA-22-0035 were determined eligible for listing in the NRHP in the report, DX Division’s Facility Strategic Plan: Consolidation and Revitalization at Technical Areas 6, 8, 9, 14, 15, 22, 36, 39, 40, 60, and 69, Vol. 1 (McGehee et al. 2005a). The SHPO concurred with these eligibility determinations on April 18, 2006. (4) TA-37-0006, TA-37-0009, and TA-37-0020 were determined eligible for listing in the NRHP in the report, High Explosives and the Nuclear Stockpile: An Assessment of Historic Buildings at Magazine Area C (TA-37), Vol. 1 (McGehee et al. 2008b). The SHPO concurred with these eligibility determinations on April 17, 2008. In a letter dated January 24, 2020, NA-LA acknowledged that the D&D of these nine NRHP-eligible facilities was an adverse effect that requires resolution through mitigation. NA-LA proposed the use of standard mitigation practices as defined in the Programmatic Agreement (PA) among the U.S. Department of Energy, National Nuclear Security Administration, Los Alamos Field Office, the New Mexico State Historic Preservation Office, and the Advisory Council on Historic Preservation Concerning Management of the Historic Properties at Los Alamos National Laboratory, Los Alamos, New Mexico. The PA states that adverse effects to NRHP-eligible buildings and structures will be resolved according to the standard practices defined in Part II, Section 10, of the Laboratory’s Cultural Resources Management Plan, A Plan for the Management of the Cultural Heritage at Los Alamos National Laboratory, New Mexico (Purtzer et al. 2019), and Section 2.B of Appendix D of the PA itself. The standard practice documentation package includes the following components: (1) Interior and exterior photography and production of archival-quality digital photographs; (2) Documentation and curation of historically significant equipment and artifacts; (3) A list of all known drawings for the property; (4) Reduced-scale reproductions of selected drawings for the property; (5) A location map that shows the location of the property relative to the entire Laboratory property; (6) Reproduction of historical TA maps; (7) A TA map that depicts the footprint of each eligible and non-eligible facility; and (8) An expanded historic context that uses oral-history interviews, if available. On March 3, 2020, the SHPO concurred with the adverse effect determination and the mitigation plan. The documentation package, as previously described, is provided in Volumes 1 and 2 of this report.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2021

Modeling particulate generation during high energy explosive events

Laser produced plasmas are used to simulate high energy events and are useful for a variety of applications e.g. in industrial sectors, such as semi-conductor manufacturing, as well as medical, environmental, and energy sectors. Particulate generation in laser produced plasmas is related to key features of the plasma: temperature and pressure evolution during plume expansion, plasma chemistry etc. Several uncertainties persist in relating initial high energy events (~microseconds) to particulate formation that happens as the plasma cools and evolves (~milliseconds).

42 ENGINEERING↗
DOE OSTI2021

First principles reactive simulation for equation of state prediction

The high cost of density functional theory (DFT) has hitherto limited the ab initio prediction of the equation of state (EOS). In this article, we employ a combination of large scale computing, advanced simulation techniques, and smart data science strategies to provide an unprecedented ab initio performance analysis of the high explosive pentaerythritol tetranitrate (PETN). Comparison to both experiment and thermochemical predictions reveals important quantitative limitations of DFT for EOS prediction and thus the assessment of high explosives. In particular, we find that DFT predicts the energy of PETN detonation products to be systematically too high relative to the unreacted neat crystalline material, resulting in an underprediction of the detonation velocity, pressure, and temperature at the Chapman–Jouguet state. The energetic bias can be partially accounted for by high-level electronic structure calculations of the product molecules. Furthermore we demonstrate a modeling strategy for mapping chemical composition across a wide parameter space with limited numerical data, the results of which suggest additional molecular species to consider in thermochemical modeling.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

2015 Geothermal Technologies Office Peer Review Summary: Energetic Materials for EGS Well Stimulation

The development of enhanced or engineered geothermal systems (EGS), by definition, includes an engineered approach to reservoir stimulation. EGS require an effective method of generating a high surface area network of fractures, or the stimulation of existing fractures, in a formation in order to increase permeability/heat-transfer. The most accepted methodologies include hydraulic fracturing and chemical stimulation. Alternative methods employing energetic materials have been employed for reservoir stimulation. For oil & gas reservoirs, this has been accomplished in the past with solid propellant gas generators and high explosives but the pressurization rate and final pressure cannot be controlled or easily adjusted in the field. Our program is investigating controlled and tailored rapid gas generation from solid, liquid and gaseous energetic formulations to operate in the chasm between conventional propellants and solid high explosives. This distinct solid, liquid and gas phase energetic materials approach has specific attributes and that could be used synergistically or individually to enhance a specific formation. This may prove to enhance the viability of using geothermal resources for power production. By employing optimized energetic materials we can tailor burn rates above propellant burn rates to optimize the gas generation rate without entering the excessive realm of the high pressures generated by high explosives. Gas phase energetic materials offer a unique method of tailoring reaction rate and final pressure. Again, rapid pressurization at rates, far exceeding quasi-static conventional hydraulic rates, can generate multiple radial wellbore fractures and potentially provide a mechanism to induce shear destabilization within the formation that enables the fractures to be self-propping. Multiple fractures from the wellbore allow efficient coupling to the existing formation fracture network. Furthermore, these techniques allow for repeated stimulations allowing fractures to be extended further. Controlled rate pressurization is a useful tool for the efficient implementation of EGS. This multi-phase approach to fracturing can eliminate the need for massive pumping equipment and the water required with conventional hydraulic fracturing methods. Additionally these methods use “green” materials with negligible environmental impact. These methods promise to be more economical than conventional stimulation techniques. Our objective is to develop a family of ideal candidate energetic systems for optimally stimulating a formation.

15 GEOTHERMAL ENERGY↗
NASA NTRS1962

STABILITY TESTS OF MONOPROPELLANTS EXPOSED TO FLAMES AND RIFLE FIRE

Tests of the stability of several monopropellants under the effects of impact and heat were conducted in order to assess the potential hazard in a propellant storage area from major fires and enemy attack. Hydrazine, hydrazine nitrate solution, n-propyl nitrate, and ethylene oxide were all tested in one-gallon aluminum containers (half of them filled to 25% and half to 95% capacity) by being subjected to oil bonfires and wood bonfires, and 20-mm incendiary, 20mm high explosive incendiary, and .30-caliber rifle fire. Aviation gasoline was tested in the same manner, for comparison. In the bonfire tests, all four monopropellants generally gave explosion intensities equivalent to one another regardless of the type of bonfire (oil or wood) or the amount of liquid in the test container. Occasionally, however, with hydrazine, hydrazine nitrate solution, and n-propyl nitrate, anomalous results occurred: there was either (a) no explosion or (b) an explosion of above average intensity. Ethylene oxide more nearly approximated the behavior of aviation gasoline than did the other monopropellants. In the rifle-fire tests, n-propyl nitrate appeared to be most shock- sensitive since it was exploded by all three types of ammunition. Hydrazine and hydrazine nitrate solution were exploded by the high-explosive ammunition, but not by the incendiary or .30-dber ammunition. Ethylene oxide was not exploded by any of the gunfire, but the liquid was ignited by both incendiary and high-explosive incendiary ammunition.

FIRING↗
DOE OSTI2026

Towards Robust Calibration of the AWSD Reactive Burn Model

Calibration of a reactive burn model for detonation of high explosive is an important step towards predictive hy drodynamic simulations of detonation. A typical calibration consists of varying model parameters (e.g., rate constants, activation energies) until results of hydrodynamic simulations match the experimental data for a certain set of ex periments. Hydrodynamic simulations of the dependence of steady detonation velocity on the radius of a cylindrical high-explosive charge - often used in such calibrations - can be computationally expensive. In this work, we propose a method where such expensive simulations are performed infrequently, and only to parameterize and refine a surrogate model for the dependence of the detonation velocity on calibrated parameters. The method is developed, implemented and applied to an example problem - calibration of the AWSD reactive burn model for important high explosive PBX 9502. Two different flavors of the surrogate model are investigated, and the calibration is performed successfully.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Intergranular Hotspots: A Molecular Dynamics Study on the Influence of Compressive and Shear Work

Numerous crystal- and microstructural-level mechanisms are at play in the formation of hotspots, which are known to govern high explosives initiation behavior. Most of these mechanisms, including pore collapse, interfacial friction, and shear banding, involve both compressive and shear work done within the material and have thus far remained difficult to separate. Here, we assess hotspots formed at shocked crystal–crystal interfaces using quasi-1D molecular dynamics simulations that isolate effects due to compression and shear. Two high explosive materials are considered (TATB and PETN) that exhibit distinctly different levels of molecular conformational flexibility and crystal packing anisotropy. Temperature and intramolecular strain energy localization in the hotspot are assessed through parametric variation of the crystal orientation and two velocity components that respectively modulate compression and shear work. The resulting hotspots are found to be highly localized to a region within 5–20 nm of the crystal–crystal interface. Compressive work plays a considerably larger role in localizing temperature and intramolecular strain energy for both materials and all crystal orientations considered. Shear induces a moderate increase in energy localization relative to unsheared cases only for relatively weak compressive shock pressures of approximately 10 GPa. These results help isolate and rank the relative importance of hotspot generation mechanisms and are anticipated to guide the treatment of crystal–crystal interfaces in coarse-grained models of polycrystalline high-explosive materials.

36 MATERIALS SCIENCE↗
DOE OSTI2025

A novel ignition model for low velocity impact of heterogeneous explosives based on interacting hot spots

While numerous studies have focused on the ignition of explosives occurring in high velocity impact and the associated shock-to-detonation transition, there has been growing interest in developing computational models focused on low-velocity impact regimes. A predictive low-velocity impact ignition model will be important for analyzing high explosive safety and potential accident scenarios. This work introduces a novel ignition model based on the concept of thermally interacting hot spots to simulate low velocity impacted heterogeneous explosives where observed ignition times are on the order of milliseconds. The model asserts that relevant hot spots are micron-sized, the typical separation between neighboring hot spots is on the order of a hundred microns, and that neighbors interact thermally through heat conduction across the interstitial region between them. To achieve tractable numerical solutions, hot spots are assumed to form a periodic array as opposed to the highly irregular positioning in an actual explosive. This idealization allows a single two hotspot system to characterize the ignition process. Consequently, the model is referred to as the two hot spot Frank-Kamenetskii ignition model. In the present study, hot spots are modeled as constant heat sources terms, but this can be extended to include grain-scale phenomena like frictional heating of micron-sized growing cracks that are confined under high pressure. Because the micron-sized features are below the scale that can be efficiently resolved at a systems level, an efficient subscale scheme based on the Method of Weighted Residuals (MWR) is used to efficiently solve the equations. In conclusion, we carry out numerical examples and analytic predictions illustrating the accuracy and the functioning of the model.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2025

Calibrating a finite-strain phase-field model of fracture for bonded granular materials with uncertainty quantification

To study the mechanical behavior of mock high explosives, an experimental and simulation program was developed to calibrate, with quantified uncertainty, a material model of the bonded granular material Idoxuridine and nitroplasticized Estane-5703. This paper reports on the efficacy of such a framework as a generalizable methodology for calibrating material models against experimental data with uncertainty quantification. Additionally, this paper studies the effect of two manufacturing temperatures and three initial granular configurations on the unconfined compressive behavior of the resulting bonded granular materials. In each of these cases, the same calibration framework was used; in that, hundreds of high-fidelity direct numerical simulations using a new, graphics processing unit-enabled, high-performance finite element method software, Ratel, were run to calibrate a finite-strain phase-field fracture model against experimental data. It was found that manufacturing temperature influenced the elastic response of the mock high explosives, with higher temperatures yielding a stiffer response. By contrast, it was found that the initial configuration of the grains had a negligible impact on the overall behavior of the mock high explosives though it remains possible that local damage accumulation within the specimens could be altered by the initial configurations. Overall, the calibration framework was successful at creating well-calibrated models, showing its usefulness as an engineering and scientific tool.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Time Dependent Analysis of Laser Heating of Metal Parts in Contact with HE

We consider the time dependent heat transfer of laser energy impinging on metal parts that are in contact with high explosives (HE). The predecessor to this calculation was TN-J4-17-2109, “Heat Transfer Analysis from Laser Energy on Metal Parts in Contact with HE”, which considered the time independent heat transfer and compared to experimental results. The intent here is to extend those results to the time dependent case. The steady-state results were developed because they were the “worst case” from a safety perspective: the steady state represents the highest possible temperature excursion. However, we found that the temperatures achieved were well above the safety limits established by the DOE High Explosives Safety Manual. Moreover, they were well above the safety limit published by the LANL / Weapons Facilities Operations (WFO) in WFO-OS-ES-48, which establishes an upper temperature limit of 70°C for metal in contact with High Explosive (HE). The J-4 response to the original results was to design, build, and deploy an interlock system for DARHT that would ensure no laser energy on the firing point when both personnel and HE were present. This system was tested and proved effective, refer TP-DARHT-1150, (12/19/2016). It was reviewed and approved by the LANL Explosives Instrumentation Review Committee, refer PRES-J4-16-2140, “DARHT Laser Diagnostics Interlock System: Presentation to the EIRC”, (2016). Although the interlock system prevented personnel from being on the firing point under conditions where the diagnostic lasers would heat metal above the WFO limit, the WFO limit was still exceeded during the Multiplexed Photonic Doppler Velocimetry (MPDV) tuning process. The only practical solution is to limit the amount of time that the MPDV lasers are engaged at full power. The diagnostics interlock system was implemented with laser shutters that can fully interrupt the beams, and these shutters can be used to limit the amount of time that the lasers will impinge on the hydrotest assembly. It is the purpose of this paper to provide quantitative guidance on what length of time can be permitted during this tuning process. Therefore, we will solve the time-dependent heat transfer equation to determine the temperature increase as a function of time. This function can be inverted to determine the maximum allowable time for energizing the lasers based on the maximum allowable temperature at the metal to HE interface.

42 ENGINEERING↗
DOE OSTI2025

AWSD reactive flow model for PBX 9404

An Arrhenius–Wescott–Stewart–Davis (AWSD) reactive flow model for high explosive PBX 9404 is developed. We specifically calibrate an AWSD model for PBX 9404 by fitting equations of state for reactants and detonation products to the results of thermochemical calculations and to experimental data from multiple sources. The calibrated equations of state are then coupled with an Arrhenius rate law based on shock temperature that describes the reaction progress during PBX 9404 detonation. The parameter values in the rate law are calibrated to experimental gas-gun data and diameter effect results. The results of the calibrated AWSD model are in strong agreement with available experimental data for PBX 9404. A similar level of agreement between predicted and experimental results is observed when the calibrated model is validated on data that were not used in the model parameterization procedure. Our results illustrate that the AWSD model is capable of accurately describing the many important properties and observables in the reactive burn of PBX 9404. Because of the historical significance of PBX 9404 in high explosives research and its current use in aging studies, this work provides an important model of a legacy material, which can be used to make comparisons to new high explosive formulations.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2024

Verification and validation of detonation-shock-dynamics relations for explosives described by general equation of state and chemical reaction models

Detonation shock dynamics is a powerful method to model the behaviour of High Explosives (HE). However in order to use this method, the underlying relationship between the local radius of curvature and the detonation speed must be known. Previous work has developed methods to calculate this effect using simple, single-step Arrhenius and polytropic gas, models for the chemical reaction and the equation of state, respectively. In recent years, more complex models for both reaction rates and equations of state have been developed which show better agreement with experimental data than these simple models, especially when considering condensed phase explosives.. This work presents the governing equations for solving these problems in a way that is generalised to use arbitrary equations of state as well as reaction models which may have more than a single step and multiple product species. This implementation is verified against exact solutions, demonstrating that the equations were implemented properly. The verified algorithm is then validated against experimental data and high fidelity simulations, showing that it is able to make accurate predictions in a regime where the underlying assumptions of the governing equations are valid. Importantly, this approach has many applications: from creating equivalent detonation shock dynamics models for existing reactive burn calibrations for HE; to developing new functional forms and calibrations of reactive burn models for condensed phase high explosives.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗