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PubMed2004

Detection of buried explosives using portable neutron sources with nanosecond timing.

Significant reduction of time needed to identify hidden explosives and other hazardous materials by the "neutron in, gamma out" method has been achieved by introducing timed (nanosecond) neutron sources-the so-called nanosecond neutron analysis technique. Prototype mobile device for explosives' detection based on a timed (nanosecond) isotopic (252)Cf neutron source has been created. The prototype is capable of identifying 400 g of hidden explosives in 10 min. Tests have been also made with a prototype device using timed (nanosecond) neutron source based on a portable D-T neutron generator with built-in segmented detector of accompanying alpha-particles. The presently achieved intensity of the neutron generator is 5x10(7)n/s into 4pi, with over 10(6) of these neutrons being correlated with alpha-particles detected by the built-in alpha-particle detector. Results of measurements with an anti-personnel landmine imitator are presented.

Blast Injuries↗
PubMed2006

Degradation of explosives-related compounds using nickel catalysts.

We report the ability of nickel-based catalysts to degrade explosives compounds in aqueous solution. Several nickel catalysts completely degraded the explosives, although rates varied. Nearly all of the organic explosive compounds tested, including 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), were rapidly degraded to below detection limits by a powdered nickel on an alumina-silicate support (Aldrich nickel catalyst). Perchlorate degradation was minimal (<25%). Degradation of TNT by Aldrich nickel catalyst resulted in apparent first-order kinetics. Significant gaseous 14C was released and collected in an alkaline solution (most likely carbon dioxide) from [14C]RDX and [14C]HMX, indicating heterocyclic ring cleavage. Significant gaseous 14C was not produced from [14C]TNT, but spectrophotometric evidence indicated loss of aromaticity. Degradation occurred in low ionic strength solutions, groundwater, and from pH 3 to pH 9. Degradation of TNT, RDX, and HMX was maintained in flow-through columns of Aldrich nickel catalyst mixed with sand down to a hydraulic retention time of 4h. These data indicate that nickel-based catalysts may be an effective means for remediation of energetics-contaminated groundwater.

Azocines↗
PubMed2004

Chemiluminescence detection systems for the analysis of explosives.

The objective of this paper is to provide a comprehensive review of explosive detection by chemiluminescence (CL) through a summary of the relevant literature in the last 5 years and a synopsis of current research topics and developments. The literature reviewed is specially addressed for the detection of a group of high explosives, containing nitrogen compounds. Most explosives compounds contain either nitro or nitrate groups which make possible their detection and quantification using detection systems based on chemiluminescent reactions. Practical considerations and experimental requirements are indicated, and the possibilities and limitations are evaluated.

Chromatography, Gas↗
PubMed2004

Investigation of the explosive hazard of mixtures containing hydrogen peroxide and different alcohols.

The explosive properties of mixtures of aqueous hydrogen peroxide (H(2)O(2)) and different alcohols (R-OH) like 2-propanol (2-PropOH), 2-methyl-2-propanol (TBA), 2-methyl-2-butanol (TAA) and 2-methyl-2-pentanol (THA) were investigated. Among others, the potential hazard of such mixtures may be characterized by their ability to react by different mechanisms of an explosion in the condensed phase, e.g. the thermal explosion or the detonation. Accordingly, the mixtures were experimentally investigated either by heating them up under confinement in different autoclaves or by exposing them to a shock wave impact applying the steel tube test. The results are discussed and compared to literature data.

Alcohols↗
PubMed2004

Explosion caused by flashing liquid in a process vessel.

An explosion occurred at a polyvinyl chloride (PVC) resin manufacturing plant. The explosion originated at an atmospheric storage vessel when it received a slurry discharge from a suspension polymerization reactor. The pressure rise caused by the uncontrolled flashing of superheated liquid vinyl chloride resulted in the complete separation of the roof from the tank shell. A cloud of vinyl chloride vapor was released and ignited resulting in a vapor cloud explosion. The accident caused significant property damage but no serious injuries. An investigation was conducted to determine the causes of the accident. It was discovered that the facility had experienced numerous overpressure incidents in the atmospheric storage vessels used as slurry tanks. Many of these incidents resulted in modest structural damage to these slurry tanks. It was determined by Exponent that the rapid flashing of residual liquid monomer present in the product slurry stream caused the earlier overpressure incidents. The facility operator did not adequately investigate or document these prior overpressure events nor did it communicate their findings to the operating personnel. Thus, the hazard of flashing liquid vinyl chloride was not recognized. The overpressure protection for the slurry tanks was based on a combination of a venting system and a safety instrumentation system (SIS). The investigation determined that neither the venting system nor the SIS was adequate to protect the slurry tank from the worst credible overpressure scenario. Fundamentally, this is because the performance objectives of the venting system and SIS were not clearly defined and did not protect against the worst credible overpressure scenario. The lessons learned from this accident include: use prior incident data for recognizing process hazards; identify targets vulnerable to these hazards; explicitly define performance objectives for safeguards to protect against the worst credible overpressure scenario. The ultimate lesson learned here is that a liquid trapped under pressure above its normal boiling point represents an overpressure hazard. To avoid exceeding the design pressure of the receiving vessel, the superheated liquid must be discharged slowly so that the vapor production rate caused by flashing does not exceed the venting rate of the receiving vessel.

Accidents, Occupational↗
PubMed2005

Experimentally validated 3-D simulation of shock waves generated by dense explosives in confined complex geometries.

Accidental blast wave generation and propagation in the surroundings poses severe threats for people and property. The prediction of overpressure maxima and its change with time at specified distances can lead to useful conclusions in quantitative risk analysis applications. In this paper, the use of a computational fluid dynamics (CFD) code CFX-5.6 on dense explosive detonation events is described. The work deals with the three-dimensional simulation of overpressure wave propagation generated by the detonation of a dense explosive within a small-scale branched tunnel. It also aids at validating the code against published experimental data as well as to study the way that the resulting shock wave propagates in a confined space configuration. Predicted overpressure histories were plotted and compared versus experimental measurements showing a reasonably good agreement. Overpressure maxima and corresponding times were found close to the measured ones confirming that CFDs may constitute a useful tool in explosion hazard assessment procedures. Moreover, it was found that blast wave propagates preserving supersonic speed along the tunnel accompanied by high overpressure levels, and indicating that space confinement favors the formation and maintenance of a shock rather than a weak pressure wave.

Chemical Industry↗
PubMed2006

Explosion characteristics of synthesised biogas at various temperatures.

Biogas is considered as a valuable source of renewable energy. Indeed, it can be turned into useful energy (heat, electricity, fuel) and can contribute to reduce greenhouse gas emissions. Knowledge of its safety characteristics is a very important practical issue. Experimental investigation of synthesised biogas explosion characteristics was conducted in a 20-L sphere at various temperatures (30-70 degrees C) and at atmospheric pressure. The studied biogas was made of 50% methane (CH(4)) and 50% carbon dioxide (CO(2)). It was also saturated with humidity: this composition is frequently met in digesters during waste methanisation. There are two inert gases in biogas: water vapour and carbon dioxide. Its vapour water content rises along with temperature. The presence of these inert gases modifies considerably biogas characteristics compared to the ones of pure methane: explosion limits are lowered and beyond 70 degrees C, water vapour content is sufficient to inert the mixture. Furthermore, explosion violence (estimated with the maximum rate of pressure rise values, (dp/dt)(max)) is three times lower for biogas than for pure methane at ambient temperature.

Algorithms↗
PubMed2006

Detonation temperature of high explosives from structural parameters.

A new scheme is introduced for calculating detonation temperature of different classes of high explosives. The ratio of oxygen to carbon and hydrogen to oxygen as well as specific structural parameters are the fundamental factors in the new method. An empirical new correlation is used to calculate detonation temperature of energetic compounds without considering heat contents of explosives and detonation products. Calculated detonation temperatures for both pure and explosive formulations show good agreement with respect to measured detonation temperatures and complicated computer code using BKWR and BKWS equations of state. Predicted detonation temperatures have root-mean-square (rms) percent deviation of 4.6, 14.2 and 4.6 from measured values for new method, BKWR and BKWS equations of state, respectively.

Explosive Agents↗
PubMed2006

The neurological consequences of explosives.

Neurological injuries produced by explosive blasts are the result of a cascade of events that begin with the initial explosion and evolve from the secondary, tertiary, and quaternary effects that the explosion engenders [Lavonis EJ. Blast Injuries. EMedicine.htm]. Only the results of the primary blast are predictable, and subsequent actions ripple outward in an increasingly random and chance sequence. This article reviews and explains how the ensuing chain of circumstances injures the nervous system, and what examining physicians should anticipate when they treat these patients.

Brain Injuries↗
PubMed2004

Comparison of environmental fate and transport process descriptors of explosives in saline and freshwater systems.

Environmental process descriptors are necessary to evaluate the fate and transport of munitions constituents that have been introduced into the environment. An extensive database exists for freshwater environments; however, explosives fate and transport parameters such as dissolution rates, transformation rates, and adsorption of explosives have not been evaluated under both freshwater and saline conditions to determine the applicability of the freshwater data to saline environments. The objective of this study was to determine if freshwater fate and transport processes were similar to those determined under saline water conditions. We evaluated TNT, RDX, and HMX dissolution rates, transformation rates, and adsorption under freshwater and saline conditions in batch tests. Results showed a generally close agreement. Therefore, the existing freshwater database for explosives fate and transport process descriptors can be used in marine environments.

Adsorption↗
PubMed2000

Application of solid-phase microextraction to the recovery of explosives and ignitable liquid residues from forensic specimens.

A current review of the application of solid-phase microextraction (SPME) to the analysis of ignitable liquids and explosive residues is presented along with experimental results demonstrating the relative effects of controllable variables. Variables discussed include fiber chemistry, adsorption and desorption temperatures, extraction and desorption times, fiber sampling placement (direct, headspace, and partial headspace) and matrix effects, including water content. SPME is shown to be an inexpensive, rapid and sensitive method for the analysis of ignitable liquids and high explosives residues from solid debris samples and from aqueous samples. Explosives are readily detected at parts per trillion concentrations and ignitable liquids are reproducibly detected at levels below those using conventional methods.

Chemistry Techniques, Analytical↗
PubMed2003

Oxidation of explosives by Fenton and photo-Fenton processes.

In this study, the Fenton process was used to explore the possibility of treating explosives, namely 2,4,6-trinitrophenol (PA), ammonium picronitrate (AP), 2,4-dinitrotoluene (DNT), methyl-2,4,6-trinitrophenylnitramine (Tetryl) and 2,4,6-Trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). The photo-Fenton process was also conducted to compare its oxidation efficiency with the Fenton process. The inhibition of hydroxyl radical and theory of crystal field stabilization energy were introduced in this study. Results show that oxidation efficiencies in Fenton system are in the following sequence: DNT > PA > AP > TNT > Tetryl > RDX > HMX. The degradation of the explosives obeys a pseudo-first-order behavior, and possible decomposing mechanisms are also discussed. For all explosives, the oxidation rates significantly increased with increasing the concentration of Fe(II), as well as illumination with UV light.

Environmental Pollution↗
PubMed2001

Analysis of fire and explosion hazards of some hydrocarbon-air mixtures.

Hazards caused by leakage of hydrocarbons have long been a problem. In this paper, the critical initiation energy and explosion limits of some hydrocarbon-air mixtures have been measured in confined (rectangle shock tube) and unconfined (plastic bag) condition tests. Two dimensionless parameters are suggested to compare the fire and explosion hazards of different hydrocarbons. Additionally, a series of experiments was performed to determine the influence of chemical additives on the fire and explosion hazards of some hydrocarbon-air mixtures in confined (rectangle shock tube) tests. These results relate directly to flammability and reactivity of hydrocarbon air mixtures. Such measurements are very important for hydrocarbon safety.

Air↗
PubMed2003

The use of aerosol formation, flammability, and explosion information for heat-transfer fluid selection.

The devastating consequences of aerosol/mist explosions have been widely documented, and there are currently efforts to understand the mechanisms of formation and explosion of aerosols. Heat-transfer fluids (HTFs) are particularly susceptible to these hazards, because they are utilized under high pressures and below their flash points, making them more prone to leaking as aerosols. In fact, there is a critical need during design stages for a perception of explosion risks associated with the selection of HTFs. This paper discusses a novel scheme to integrate the knowledge of HTF aerosol formation from leaks in process equipment into the selection of HTFs during the design process. Hazards of aerosols formed from leaks are classified qualitatively using process pressure and droplet sizes.

Aerosols↗
PubMed2002

Burns due to gunpowder explosions in fireworks factory: a 13-year retrospective study.

The aim of this study was to evaluate the epidemiology of burns due to gunpowder explosions in fireworks factories. Three hundred and fifty-one patients having burns caused by gunpowder explosions in a fireworks factory were admitted to our center from 1 January 1987 to 31 December 1999 and the clinical notes of 339 patients were available for review. Data on age, sex, size, depth and sites of burn, incidence by month, inhalation injury, associated injuries, number of operations, length of hospital stay, morbidity, mortality, and causes of explosions were recorded. The majority of the patients were male, with a mean age of 36.7 years. The mean total burn surface area was 40.9%, mostly deep burns. The commonest areas of the body to be injured were the head and neck. One hundred and eighty-five patients (55%) were injured in December, November, and January. Sixty-five patients (19%) had an inhalation injury, 35 having tracheotomies and mechanical ventilation. Thirty-five patients (10%) had associated injuries, the commonest being the fracture of limbs (25 patients). Two hundred and thirty-two patients (68%) required operations while the number of operations including debridement and grafting, or tracheotomy, per patient were 2.7. The mean time in hospital of the survivors was 32 days with a range of 1-94 days. Acute respiratory distress syndrome (ARDS) and sepsis were the commonest complications during the early post-burn period (7 days or less) and the later period (>7 days), respectively. Forty-four patients died in this series giving a mortality rate of 13%. The commonest cause of death was sepsis (27 patients), followed by multiple organ dysfunction syndrome (MODS) (11 patients). Most accidents (71%) were caused by too much gunpowder put in at one time and accidents resulting from carelessness while making fireworks. Prevention measures are also discussed.

Adolescent↗
PubMed2002

Gunpowder explosion burns in fireworks factory: causes of death and management.

The mortality rate of gunpowder explosion burns from fireworks factory accidents was high. The aim of this study was to evaluate the impact of different managements on outcome of these burns patients and to optimize treatment measures and decrease the morbidity and mortality. During the period from January 1987 to December 1999 in our center, 44 patients burned in gunpowder explosions died. Fifty sex-, age-, TBSA- and full-thickness-matched patients who survived were selected randomly as a comparison group. Data on time and causes of death, fluid resuscitation, and management of inhalation injury, associated injuries and wound were collected. Half of the deaths occurred during the first week after burn. The commonest cause of death was sepsis (27 patients), followed by MODS (11 patients), then hypovolaemic shock (4 patients) and pulmonary infection (2 patients). Thirty-six dead patients and 10 surviving patients had received insufficient fluid resuscitation and developed severe shock. Prophylactic tracheotomy was undertaken in 15 patients, of whom 6 died. Thirty-two patients had undergone emergency tracheotomies, of which 29 died. All associated injuries had been well-managed and no death was related to associated injuries or their complications directly. In the group of patients who died, 20 had undergone early excision (within 1 week of injury) and grafting. The number of patients in the survivor group who underwent early excision and grafting was 31. These results indicate that the sepsis and MODS are the two commonest causes of death for the patients who sustained burns by gunpowder explosions in fireworks factory. The optimal managements of this type of burn are as follows: (1) sufficient fluid resuscitation and invasive monitoring if necessary; (2) prophylactic tracheotomy and mechanical ventilation for the patients whose upper-airway edema is present or airway patency is threatened; (3) early excision and grafting of lager-deep wounds and covering with allograft with microautograft (1:10); (4) life-threatening associated injuries must be treated immediately after admitting.

Accidents, Occupational↗
PubMed1983

[Explosion of intestinal gas during surgery].

Two cases of colonic gas explosion during surgery are reported. The treatment of the lesions required a partial colectomy in one case and a total colectomy in the other case. The different factors involved in such accidents are discussed. Three factors are necessary to trigger off an explosion of intestinal gases: the presence of combustible gases (hydrogen, methane), the presence of combustive gases (oxygen, nitrous oxide) and an initiating heat source (endoscopic or surgical electrocautery). The mannitol used for bowel cleansing undergoes partial colonic bacterial fermentation increasing the intraluminal concentration of hydrogen. During anaesthesia the oxygen-nitrous oxide mixture increases the intestinal concentration of these two major combustive gases. Electrocautery provides the spark triggering the explosion. The use of mannitol for colonic preparation should be questioned; the use of electrocautery to open the colon is advised against.

Aged↗
PubMed2006

Highly sensitive electrochemical detection of trace liquid peroxide explosives at a Prussian-blue 'artificial-peroxidase' modified electrode.

A highly sensitive electrochemical assay of the peroxide-based explosives triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) at a Prussian-blue (PB) modified electrode is reported. The method involves photochemical degradation of the peroxide explosives and a low potential (0.0 V) electrocatalytic amperometric sensing of the generated hydrogen peroxide at the PB transducer and offers nanomolar detection limits following a short (15 s) irradiation times. The electrochemical sensing protocol should facilitate rapid field screening of peroxide explosives.

Bridged Bicyclo Compounds, Heterocyclic↗