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Title: The Thermal Response of TATB-Based PBXs

Abstract

In the design mode of operation, TATB-­based PBXs, such as PBX 9502 or LX-­17, are promptly initiated by a detonator and booster system. In abnormal situations, such as accidents, a wide variety of non-­design-­mode insults can arise and it is desirable that these do not produce detonation but rather that, at most, they lead to a low chemical energy release. The most significant abnormal hazard is the direct shock initiation threat arising from high-­velocity fragment impact. This is quite well defined and may result in a detonative response if the fragment is large enough and fast enough. However, it is of considerably greater significance to the safety envelope of these explosives whether they are at all capable of DDT (deflagration-­to-­detonation transition), either at ambient or elevated temperatures since accidental insults to the explosive, either mechanical or thermal, that may produce local burning are both more numerous and more likely than shock loading. The purpose of this document is to demonstrate, based on the accumulated body of conservative experimental testing, that in explosive geometries and masses relevant to the Weapons Program, TATB-­based PBXs do not present a deflagration-­to-­detonation transition (DDT) hazard at any temperature. This is a significant statement since itmore » removes detonative outcome concerns from the majority of insult scenarios on TATB-­based charges. It does not address the response of included detonator and booster assemblies, the response of which must be considered separately.« less

Authors:
 [1];  [1];  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1168714
Report Number(s):
LA-UR-15-20327
DOE Contract Number:
AC52-06NA25396
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE; 98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION

Citation Formats

Dickson, Peter, Parker, Gary Robert, and Rae, Philip John. The Thermal Response of TATB-Based PBXs. United States: N. p., 2015. Web. doi:10.2172/1168714.
Dickson, Peter, Parker, Gary Robert, & Rae, Philip John. The Thermal Response of TATB-Based PBXs. United States. doi:10.2172/1168714.
Dickson, Peter, Parker, Gary Robert, and Rae, Philip John. 2015. "The Thermal Response of TATB-Based PBXs". United States. doi:10.2172/1168714. https://www.osti.gov/servlets/purl/1168714.
@article{osti_1168714,
title = {The Thermal Response of TATB-Based PBXs},
author = {Dickson, Peter and Parker, Gary Robert and Rae, Philip John},
abstractNote = {In the design mode of operation, TATB-­based PBXs, such as PBX 9502 or LX-­17, are promptly initiated by a detonator and booster system. In abnormal situations, such as accidents, a wide variety of non-­design-­mode insults can arise and it is desirable that these do not produce detonation but rather that, at most, they lead to a low chemical energy release. The most significant abnormal hazard is the direct shock initiation threat arising from high-­velocity fragment impact. This is quite well defined and may result in a detonative response if the fragment is large enough and fast enough. However, it is of considerably greater significance to the safety envelope of these explosives whether they are at all capable of DDT (deflagration-­to-­detonation transition), either at ambient or elevated temperatures since accidental insults to the explosive, either mechanical or thermal, that may produce local burning are both more numerous and more likely than shock loading. The purpose of this document is to demonstrate, based on the accumulated body of conservative experimental testing, that in explosive geometries and masses relevant to the Weapons Program, TATB-­based PBXs do not present a deflagration-­to-­detonation transition (DDT) hazard at any temperature. This is a significant statement since it removes detonative outcome concerns from the majority of insult scenarios on TATB-­based charges. It does not address the response of included detonator and booster assemblies, the response of which must be considered separately.},
doi = {10.2172/1168714},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2015,
month = 1
}

Technical Report:

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  • We detail a modeling approach to simulate the anisotropic thermal expansion of polycrystalline (1,3,5-triamino-2,4,6-trinitrobenzene) TATB-based explosives that utilizes microstructural information including porosity, crystal aspect ratio, and processing-induced texture. This report, the first in a series, focuses on nonlinear thermal expansion of “neat-pressed” polycrystalline TATB specimens which do not contain any binder; additional complexities related to polymeric binder and irreversible ratcheting behavior are briefly discussed, however detailed investigation of these aspects are deferred to subsequent reports. In this work we have, for the first time, developed a mesoscale continuum model relating the thermal expansion of polycrystal TATB specimens to their microstructuralmore » characteristics. A self-consistent homogenization procedure is used to relate macroscopic thermoelastic response to the constitutive behavior of single-crystal TATB. The model includes a representation of grain aspect ratio, porosity, and crystallographic texture attributed to the consolidation process. A quantitative model is proposed to describe the evolution of preferred orientation of graphitic planes in TATB during consolidation and an algorithm constructed to develop a discrete representation of the associated orientation distribution function. Analytical and numerical solutions using this model are shown to produce textures consistent with previous measurements and characterization for isostatic and uniaxial “die-pressed” specimens. Predicted thermal strain versus temperature for textured specimens are shown to be in agreement with corresponding experimental measurements. Using the developed modeling approach, several simulations have been run to investigate the influence of microstructure on macroscopic thermal expansion behavior. Results from these simulations are used to identify qualitative trends. Implications of the identified trends are discussed in the context of thermal deformation of engineered components whose consolidation process is generally more complex than isostatic or die-pressed specimens. Finally, an envisioned application of the modeling approach to simulating thermal expansion of weapon systems and components is outlined along with necessary future work to introduce the effects of binder and ratcheting behavior. Key conclusions from this work include the following. Both porosity and grain aspect ratio have an influence on the thermal expansion of polycrystal TATB considering realistic material variability. Thepreferred orientation of the single crystal TATB [001] poles within a polycrystal gives rise to pronounced anisotropy of the macroscopic thermal expansion. The extent of this preferred orientation depends on the magnitude of deformation, and consequently, is expected to vary spatially throughout manufactured components much like porosity. The modeling approach presented here has utility toward bringing spatially variable microstructural features into macroscale system engineering modelsAbstract Not Provided« less
  • A series of unconfined one-dimensional heating experiments in slab geometry was conducted with TNT, Comp. B, plastic-bonded HMX, TATB, DATB, and NQ. The explosive samples were heated on one surface at heating rates between 10 and 25/sup 0/C/min. The experimentaly determined times and temperatures to ignition were reproduced computationally, with one exception, by solving a one-dimensional heat-conduction equation containing a zero-order reaction energy source term and a time-dependent temperature boundary condition. The one exception was plastic-bonded NQ. Unconfined plastic-bonded NQ did not ignite under the experimental conditions used. The heat-transfer mechanism in molten TNT, as expected, was convective; and formore » molten Comp. B, conductive. A reactive heat-transfer program, EXPLO, was written that is capable of solving the convective transfer mode and accepting mixtures of explosives reacting with first-order kinetics.« less
  • Thermal conductivity data are given for TATB, RX-03-AU, and RX-03-BB. (TFD)
  • Determining the need for air conditioning can be based on a wide variety of factors. To date, the only criteria that have been written and can be referenced are those of several federal organizations and many are not really criteria in the true sense of the word. They are guidelines to be used in the determination of fund allocation; in other words, provisions are made to air condition federal facilities in specific geographical locations if pertinent weather characteristics of that locality meet certain requirements. The concept is presented that true criteria can be established based both on weather characteristics ofmore » the locality as well as characteristics of the building or structure under consideration. Details are given of a study showing the feasibility of such a scheme. A simulation was made of two proposed residences in several geographical localities. For the simulation, actual hour-by-hour weather data was used in conjunction with a sophisticated computer program. The results revealed, for the non air-conditioned spaces, the extent and duration of undesirable indoor conditions based upon generally accepted comfort indices. The concept of a new ''comfort'' or ''discomfort'' index called Predicted Indoor Habitability Index (PIHI) is introduced. The authors indicate the way in which a criterion could be established that would be in the form of tables indicating, for a given specified building and geographical locality, whether mechanical cooling should or should not be installed.« less