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At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Isolator fragmentation and explosive initiation tests

Three tests were conducted to evaluate the effects of firing an isolator in proximity to a barrier or explosive charge. The tests with explosive were conducted without a barrier, on the basis that since any barrier will reduce the shock transmitted to the explosive, bare explosive represents the worst-case from an inadvertent initiation perspective. No reaction was observed. The shock caused by the impact of a representative plastic material on both bare and cased PBX 9501 is calculated in the worst-case, 1-D limit, and the known shock response of the HE is used to estimate minimum run-to-detonation lengths. The estimates demonstrate that even 1-D impacts would not be of concern and that, accordingly, the divergent shocks due to isolator fragment impact are of no concern as initiating stimuli.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2018

Shear Heating of Explosives using the Crush Gun; FY2018 Report

Explosives subject to rapid mechanical deformation can experience large internal velocity gradients; this is a dissipative process, causing internal temperature rise. If this internal frictional heating is sufficiently large and sufficiently localized it can cause ignition of the explosive. Modeling the heat deposition that arises from mechanical insult is an ongoing effort, and additional experimental data is required to develop the model [1]. Apneumatic gun apparatus was designed and built to deliver crushing impacts at velocities of 0-70 m/s. The apparatus is designed to halt the projectile approximately 1 mm before impacting the sapphire imaging surface, preventing a complete “pinch” condition from attaining. The primary diagnostics include high-speed visible videography and infrared imaging to determine spatial temperature rise of the sample during impact. Forty-seven tests were performed with the apparatus during FY18, on four different explosives: Comp-B, PBX 9501, LX-07, and LX-14.No measurable heating was observed with Comp-B at a nominal velocity of 58 m/s. A maximum temperature rise of 17 °C was recorded with PBX 9501 at an impact velocity of 59 m/s. A maximum temperature rise of 32 °C was observed with LX-07 at an impact velocity of 57 m/s. A maximum temperature rise of 15 °C was observed with LX-14 at an impact velocity of 59 m/s. In contrast to drop-weight tower sensitivity testing [2,3], no ignitions were observed in any of the impacts. The lack of appreciable heating is attributed to the arrest mechanism which prevents the projectile from completing the final ~2 mm of crush. Differences between the explosive compositions are attributed primarily to binder effects.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2018

Analysis of Three-Component Rotational and Translational Ground Motions from Source Physics Experiment Chemical Explosions and Local Earthquakes

Igel et al. (2005) demonstrated that using single point measurements of translational displacement and rotational strain can reconstruct the long-period teleseismic wavefield including wave-type, apparent velocity and propagation direction. We examine if this also holds true for higher frequencies at local distances. Four co-located three-component (3C) Eentec R-1 rotational velocity sensors and Kinemetric 3C accelerometers were deployed at the Nevada National Security Site (NNSS) to record 3 Source Physics Experiment (SPE) chemical explosions with yields of 90kg (SPE-1), 997kg (SPE-2), and 905kg (SPE-3) equivalent TNT. The four sensors were deployed 1-km from the source on granite, sedimentary, and alluvium outcrops. Three small earthquakes were also recorded, a Ml 3.3 at 28 km, a Ml 2.6 at 58 km, and Ml 3.5 at 123 km distance from SPE site. From the 3C rotational and translational motions, we measured the horizontal phase velocity of 450 m/s and 1125 m/s along two separate directions from the source consistent with near-surface geology. In contrast, the horizontal phase velocity measured for the Ml 3.3 earthquake is 5.4 km/s in the 0.1 to 10 Hz band with a propagation direction consistent with the epicenter location. While the earthquake exhibited very high coherency between 3C rotational and translational motions, the explosions exhibited more coherency with P-SV waves but less for SH-waves. This may be due to explosion SH waves originating from motions along joints or scattering near the source. This difference could be exploited as a discriminant between explosions and earthquakes.

58 GEOSCIENCES↗
DOE OSTI2019

Low Temperature Time-to-Explosion Experiments in the LLNL’s ODTX/P-ODTX System

Incidents caused by fire and some operations can heat energetic materials that may lead to thermal explosion and result in structural damage and casualty. Thus, explosive thermal sensitivity is an important topic for oilfield perforating operations and impacts perforating system performance and safety. Explosives have time-dependent temperature limits which can lead to thermal decomposition when exceeded and, under some circumstances, can result in performance losses and safety hazards. The One-Dimensional-Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory (LLNL) has been used for decades to characterize thermal safety of energetic materials. In this study, an integration of a pressure monitoring element has been added into the ODTX system (P-ODTX) to perform extended thermal experiments on HMX at three temperatures 160 °C, 170 °C and 185 °C. The tests generate time-temperature data as well as useful gas pressure data to assist with the thermal safety assessment of the energetics and systems that use the energetics. This report summarizes results of the 3 tests that were performed from July 2018 to November 2018.

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

Light Initiated High Explosive Driven Flyer Plate Impulse Generation Technique For Material and Structural Response

The objective for this research has been to develop a method to induce a high frequency, large amplitude shock pulse into materials and structures as an above-ground laboratory simulation of an exo-atmospheric cold x-ray induced blow-off event. This work builds on the successes of direct-spray Light Initiated High Explosive impulse delivery technique, in order to drive a flyer to a desired impact velocity to induce the proper combined material and structural response of the target. The reported development focuses on flyer velocity from explosive initiation to target impact to flyer rebound. A comprehensive derivation of an analytical model to predict flyer velocity as a function of explosive deposition and flyer properties is presented. One-and two-dimensional test series were conducted to evaluate impulse delivery and impact pressure, as well as target material and structural response. Experimental results show good agreement in flyer velocity between that predicted by the developed theory and that inferred by impulse delivery. A definitive material response was measured in each of the one-dimensional targets. The structural strain response measured in the ring experiments showed excellent agreement with both the predicted flyer performance and the analytical strain solution for a cosine distributed impulsive loading. This work has focused on the utilization of analytical, hydrocode, and test analysis to confirm that a LIHE driven flyer impulse technique can be an effective simulation of a cold x-ray blow-off event. It is shown that a thin metallic flyer plate can be explosively accelerated to impact a target with sufficient energy to generate an impulsive load which induces both structural and material response in a test item.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Low-frequency Electromagnetic Detection Limits of Underground Nuclear Explosions

Underground nuclear explosions produce a broadband electromagnetic signal that can propagate to the surface at some distance. We perform a logistic regression on historical electromagnetic detections to calculate a probabilistic detection curve for prediction of the propagation distance for any given underground nuclear explosion. The curve predicts positive detections at scaled ranges of 2414.6, 2025.7, 1908.3, and 1672.4 m/ktonne 1/3 at probabilities of 50, 90, 95 and 99%, respectively. For a theoretical 100 ktonne underground nuclear explosion these scaled ranges translate to absolute ranges of 11.2, 9.4, 8.9, and 7.8 km at probabilities of 50, 90, 95 and 99%, respectively. We also motivate a need for improved electromagnetic sensor design and deployment by extending the detection analysis using the quoted signal-to-noise ratio of two and noise amplitude of 10 pT along with attenuation relationships that go as 1/r to 1/r 3 . We find that reducing the noise floor by a factor often could extend the detection limit to approximately 5 to 25 km/ktonne 1/3 , which translates to 24 to 112 km for a theoretical 100 ktonne underground nuclear explosion.

58 GEOSCIENCES↗
DOE OSTI2017

EDS V26 Vessel Clamp Explosive Test Report

This report documents the results of explosive re-qualification tests of the EDS V26 Vessel that were conducted at Sandia National Laboratories in Albuquerque, New Mexico in May 2015 following the retrofitting of the vessel with a three piece clamp for use on the P2A system. The V26 containment vessel is the second EDS vessel to be fabricated under Code Case 2564 of the ASME Boiler and Pressure Vessel Code, which provides rules for the design of impulsively loaded vessels. The explosive rating for the vessel, based on the code case, is nine (9) pounds TNT-equivalent for up to 637 detonations. The goals of the tests were to qualify the vessel, particularly the clamping system, for explosive use. The explosive tests consisted of a 9 pound bare charge of Composition C-4 (equivalent to 11.25 pounds TNT), followed by a 7.2 pound bare charge of Composition C-4 (equivalent to 9 pounds of TNT). Helium permeation measurements of the seal and strain measurements using a pi tape and strain gauges were made. All vessel acceptance criteria were met.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Standardizing an Intermediate-Scale High Explosive Safety Test Suite

Small-scale safety testing, while successful in screening out extremely dangerous explosive compositions, does not fully characterize the explosive hazards associated with handling larger, consolidated or bare charges. It is proposed that intermediate-scale tests using consolidated charges in the range 25 mg – 1 kg are warranted to satisfactorily address the hazards. A standard for this intermediate-scale testing should be developed, proofed, peer-reviewed and adopted to assist in the development of safe new high explosive compositions across the complex. This whitepaper explains why current small-scale safety testing is insufficient to characterize the handling hazard, identifies the guiding aspects of explosive response that drive the handling hazards associated with larger consolidated charges, and proposes a suite of tests/experiments that can serve as a starting point for an intermediate-scale safety standard.

42 ENGINEERING↗
DOE OSTI2024

A multi-Physics Experiment for Low-Yield Nuclear Explosion Monitoring

A series of multi-physics experiments, referred to as Physics Experiment 1 (PE1) is underway at the United States’ Nevada National Security Site (NNSS). The PE1 series includes detonations of three underground chemical explosions in P-tunnel, with fully coupled (PE1 A), partially decoupled (PE1 D L ), and fully decoupled (PE1 B) emplacements. Canisters with gas tracers are imbedded in the explosives, and the tracers are released when the canister is destroyed by the detonation. A dedicated electromagnetic (EM) experiment (EMX) generates well-characterized EM signals at an underground location near the chemical explosive experiments. A series of atmospheric experiments (METEX, REACT, and METREX) release smoke and radioactive tracers around Aqueduct Mesa to test gas transport in complex topography. Each of the chemical explosive experiments includes a network of sensors to record seismic, acoustic, and electromagnetic waves, measurement of atmospheric conditions, and air sample collection for measurement of tracer concentration. EMX records EM signals underground and on the surface of Aqueduct Mesa. METEX, REACT, and METREX include measurement of atmospheric condition, as well as tracking smoke releases. REACT and METREX add low-level radioactive gas tracers to the atmospheric releases.

58 GEOSCIENCES↗
DOE OSTI2024

Temperature and Pressure Instrumentation for LYNM PE1 Chemical Explosive Testing

Underground chemical explosive testing has been conducted at the Nevada National Security Site under the Physics Experiment 1 (PE1) to validate explosive computer modeling and, ultimately, improve the accuracy of subsurface explosive detection. This SAND Report describes the dynamic temperature and pressure measurements within the chamber induced by the chemical explosive for the first of three experiments, PE1-A. The report details the instrumentation used for the experiment, the emplacement of the hardware, and the measured results. Dynamic temperature measurements were accomplished with the use of optical spectrometers and dynamic pressure was measured with a series of high-rated pressure transducers. This report includes details of the design and results of four cavity sensor systems used to measure early-time temperature, early-time pressure, late-time temperature, and late time pressure. The outcomes of PE1-A were used to inform the design of the remaining PE1 series experiments, PE1-B and PE1-DL.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2016

Type Ia Supernova Explosions From Hybrid Carbon–Oxygen–Neon White Dwarf Progenitors

Motivated by recent results in stellar evolution that predict the existence of hybrid white dwarf (WD) stars with a C–O core inside an O–Ne shell, we simulate thermonuclear (Type Ia) supernovae from these hybrid progenitors. We use the FLASH code to perform multidimensional simulations in the deflagration-to-detonation transition (DDT) explosion paradigm. Our hybrid progenitor models were produced with the MESA stellar evolution code and include the effects of the Urca process, and we map the progenitor model to the FLASH grid. We performed a suite of DDT simulations over a range of ignition conditions consistent with the progenitor's thermal and convective structure assuming multiple ignition points. To compare the results from these hybrid WD stars to previous results from C–O WDs, we construct a set of C–O WD models with similar properties and similarly simulate a suite of explosions. We find that despite significant variability within each suite, trends distinguishing the explosions are apparent in their ${}^{56}\mathrm{Ni}$ yields and the kinetic properties of the ejecta. We compare our results with other recent work that studies explosions from these hybrid progenitors.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Dependence of Dust Formation on the Supernova Explosion

We investigate the properties, composition, and dynamics of dust formation and growth for a diverse set of core-collapse supernovae (CCSNe), with 15, 20, and 25 M ⊙ progenitor masses, explosion energies ranging from 0.5 to 120 foe, and varied engine type. These explosions are evolved with a 1D Lagrangian hydrodynamics code out to a minimum of 1157 days to model the ejecta as it expands and cools. A multigrain dust nucleation and growth model is applied to these results. We find that higher explosion energies lead to an earlier onset of dust formation, smaller grain sizes, and larger silicate abundances. Further, we see that nuclear burning during the explosion leads to enhanced formation of silicate dust. Finally, we build composite models from our suite to predict the efficiency of CCSN dust production as a function of metallicity.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Black Hole Formation Accompanied by the Supernova Explosion of a 40 M ⊙ Progenitor Star

Abstract We have simulated the collapse and evolution of the core of a solar-metallicity 40 M ⊙ star and find that it explodes vigorously by the neutrino mechanism, despite its very high “compactness.” Within ∼1.5 s of explosion, a black hole forms. The explosion is very asymmetrical and has a total explosion energy of ∼1.6 × 10 51 erg. At black hole formation, its baryon mass is ∼2.434 M ⊙ and gravitational mass is 2.286 M ⊙ . Seven seconds after black hole formation, an additional ∼0.2 M ⊙ is accreted, leaving a black hole baryon mass of ∼2.63 M ⊙ . A disk forms around the proto−neutron star, from which a pair of neutrino-driven jets emanates. These jets accelerate some of the matter up to speeds of ∼45,000 km s −1 and contain matter with entropies of ∼50. The large spatial asymmetry in the explosion results in a residual black hole recoil speed of ∼1000 km s −1 . This novel black hole formation channel now joins the other black hole formation channel between ∼12 and ∼15 M ⊙ discovered previously and implies that the black hole/neutron star birth ratio for solar-metallicity stars could be ∼20%. However, one channel leaves black holes in perhaps the ∼5–15 M ⊙ range with low kick speeds, while the other leaves black holes in perhaps the ∼2.5–3.0 M ⊙ mass range with high kick speeds. However, even ∼8.8 s after core bounce the newly formed black hole is still accreting at a rate of ∼2 × 10 −2 M ⊙ s −1 , and whether the black hole eventually achieves a significantly larger mass over time is yet to be determined.

Astronomy & Astrophysics↗
DOE OSTI2025

Physics-driven Explosions of Stripped High-mass Stars: Synthetic Light Curves and Spectra of Stripped-envelope Supernovae with Broad Light Curves

Stripped-envelope supernovae (SESNe) represent a significant fraction of core-collapse supernovae, arising from massive stars that have shed their hydrogen and, in some cases, helium envelopes. The origins and explosion mechanisms of SESNe remain a topic of active investigation. In this work, we employ radiative-transfer simulations to model the light curves and spectra of a set of explosions of single, solar-metallicity, massive Wolf–Rayet stars with ejecta masses ranging from 4 to 11 M ⊙ , which were computed from a turbulence-aided and neutrino-driven explosion mechanism. We analyze these synthetic observables to explore the impact of varying ejecta mass and helium content on observable features. We find that the light curve shape of these progenitors with high ejecta masses is consistent with observed SESNe with broad light curves but not the peak luminosities. The commonly used analytic formula based on rising bolometric light curves overestimates the ejecta mass of these high-initial-mass progenitor explosions by a factor of up to 2.6. In contrast, the calibrated method by Haynie et al., which relies on late-time decay tails, reduces uncertainties to an average of 20% within the calibrated ejecta mass range. Spectroscopically, the He I 1.083 μm line remains prominent even in models with as little as 0.02 M ⊙ of helium. However, the strength of the optical He I lines is not directly proportional to the helium mass but instead depends on a complex interplay of factors such as the 56 Ni distribution, composition, and radiation field. Thus, producing realistic helium features requires detailed radiative transfer simulations for each new hydrodynamic model.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2026

Presupernova O–C Shell Mergers Could Produce More 44 Ti than the Explosion

The formation of 44 Ti in massive stars is thought to occur during explosive nucleosynthesis; however, recent studies have shown it can be produced during O–C shell mergers prior to core collapse. We investigate how mixing according to 3D macrophysics derived from hydrodynamic simulations impacts presupernova O–C shell merger nucleosynthesis and if it can dominate explosive supernova production of 44 Ti and other radioactive isotopes. We compare a range of observations and models of explosive 44 Ti yields to preexplosive multizone mixing–burning nucleosynthesis simulations of an O–C shell merger in a 15 M ⊙ Z = 0.02 stellar model with mixing conditions corresponding to different 3D hydrodynamic mixing scenarios. Radioactive species produced in the O shell have a multidex spread in preexplosive yield predictions across different 3D mixing scenarios of 1.54 and 2.14 dex on average, depending on mass cut. 44 Ti has the largest spread of 4.78 and 4.81 dex depending on mass cut. Further, we show that the preexplosive production of 44 Ti can be larger than the explosive production of models and can match observations. Our results also show that 3D mixing physics enhances 44 Ti in 1D models without modifying 56 Ni yields. We conclude that quantitative predictions of 44 Ti and other radioactive species more broadly require an understanding of the 3D hydrodynamic mixing conditions present during the O–C shell merger.

Issa, Joshua [University of Victoria, BC (Canada);↗
DOE OSTI2014

Apparatus and methods for real-time detection of explosives devices

The present disclosure relates, according to some embodiments, to apparatus, devices, systems, and/or methods for real-time detection of a concealed or camouflaged explosive device (e.g., EFPs and IEDs) from a safe stand-off distance. Apparatus, system and/or methods of the disclosure may also be operable to identify and/or spatially locate and/or detect an explosive device. An apparatus or system may comprise an x-ray generator that generates high-energy x-rays and/or electrons operable to contact and activate a metal comprised in an explosive device from a stand-off distance; and a detector operable to detect activation of the metal. Identifying an explosive device may comprise detecting characteristic radiation signatures emitted by metals specific to an EFP, an IED or a landmine. Apparatus and systems of the disclosure may be mounted on vehicles and methods of the disclosure may be performed while moving in the vehicle and from a safe stand-off distance.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2015

Method for selective detection of explosives in mass spectrometer or ion mobility spectrometer at parts-per-quadrillion level

A method for selective detection of volatile and non-volatile explosives in a mass spectrometer or ion mobility spectrometer at a parts-per-quadrillion level without preconcentration is disclosed. The method comprises the steps of ionizing a carrier gas with an ionization source to form reactant ions or reactant adduct ions comprising nitrate ions (NO.sub.3.sup.-); selectively reacting the reactant ions or reactant adduct ions with at least one volatile or non-volatile explosive analyte at a carrier gas pressure of at least about 100 Ton in a reaction region disposed between the ionization source and an ion detector, the reaction region having a length which provides a residence time (tr) for reactant ions therein of at least about 0.10 seconds, wherein the selective reaction yields product ions comprising reactant ions or reactant adduct ions that are selectively bound to the at least one explosive analyte when present therein; and detecting product ions with the ion detector to determine presence or absence of the at least one explosive analyte.

47 OTHER INSTRUMENTATION↗
DOE OSTI2018

Explosives mimic for testing, training, and monitoring

Additive Manufacturing (AM) is used to make mimics for explosives. The process uses mixtures of explosives and matrices commonly used in AM. The explosives are formulated into a mixture with the matrix and printed using AM techniques and equipment. The explosive concentrations are kept less than 10% by wt. of the mixture to conform to requirements of shipping and handling.

36 MATERIALS SCIENCE↗