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The Nature, Sources, and Environmental Chemistry of Hazardous Wastes
Published in Stanley E. Manahan, Environmental Chemistry, 2022
For regulatory and legal purposes in the United States, hazardous substances are listed specifically and are defined according to general characteristics. Under the authority of the RCRA, the US EPA defines hazardous substances in terms of the following characteristics: Ignitability, characteristic of substances that are liquids, the vapors of which are likely to ignite in the presence of ignition sources; nonliquids that may catch fire from friction or contact with water and which burn vigorously or persistently; ignitable compressed gases; and oxidizers.Corrosivity, characteristic of substances that exhibit extremes of acidity or basicity or a tendency to corrode steel.Reactivity, characteristic of substances that have a tendency to undergo violent chemical change (examples are explosives, pyrophoric materials, water-reactive substances, or cyanide- or sulfide-bearing wastes).Toxicity, defined in terms of a standard extraction procedure followed by chemical analysis for specific substances.
Terms and Definitions
Published in Rick Houghton, William Bennett, Emergency Characterization of Unknown Materials, 2020
Rick Houghton, William Bennett
Highly reactive compounds tend to release large amounts of energy quickly. Reactivity is affected by concentration, temperature, pressure, surface area, the presence of contaminants, and other physical characteristics. For example, a block of magnesium submerged in water is merely wet. The same block of magnesium ground into a fine powder and wetted with water will begin to react and self-heat. The heat will increase the rate of the reaction to the point of ignition.
General Princlpes
Published in Martin B., S.Z., of Industrial Hygiene, 2018
Reactivity is the ability of a substance to undergo rapid, sometimes violent reactions under certain conditions. For example, when water and sodium come into contact, the heat generated by the reaction can cause both the hydrogen and sodium to ignite. Explosive materials, such as TNT, are considered highly reactive. For the industrial hygiene professional, it is important to note that, in addition to water combining with a substance, an acid, a base, or air can cause an uncontrolled reaction to occur. Unfortunately, some materials need no additional substance to react and are considered self-reactive. This means they contain both an oxidant and a reducing agent in the same compound. Nitroglycerin is a good example of a self-reactive substance. Table 2.2 contains a list of reactive compounds and structures that may be of importance to the industrial hygiene professional.
Development of new treatment of fuel isotope vector in the core disruptive accident analysis of fast reactors
Published in Journal of Nuclear Science and Technology, 2023
Hirotaka Tagami, Shinya Ishida, Yoshiharu Tobita
The target reactor is same as the target reactor in Section 3.1. The calculation domain covers the outer perimeter of radial shield in horizontal direction and lower plenum to upper cover gas region in axial direction (Figure 7) by Cartesian coordinate system. Each SA is expressed with 1 cell in horizontal plane. The domain has 3131 cells in horizontal direction and 79 in axial direction. The SIMMER calculation needs initial reactivity and power at the initial state. The initial reactivity and power are assumed 0 $ and the rated operation power in all cases. Same as Section 3.1, three types of fuel isotope classification, which are Pu-vector model, the current two fuel components with the optimized and the fertile/fissile cases, are applied to each calculation case. In these cases, material, temperature and neutronic power distributions affects each other. Generally, the reactivity change strongly depends on material and temperature distributions. Because the target is investigation of the effect with isotope assignment, this section deals with time ranges in which the effect of material and temperature distribution differences does not appear.
Gasification of Brazilian coal-chars with CO2: effect of samples’ properties on reactivity and kinetic modeling
Published in Chemical Engineering Communications, 2019
Michele D. Domenico, Gabriela C. Collazzo, Tatiana R. Pacioni, Humberto J. José, Regina F. P. M. Moreira
As described above, other features related to the coal properties can affect the reactivity. For example, the vitrinite and liptinite contents can be associated with an increased reactivity for RS1 and RS2 coal chars (Walker, 1981; White et al., 1989). Also, the higher surface areas found for these coals (Table 1) could contribute to enhance the gasification rate when compared to SC1 and SC2 coal chars. In practice, greater reactivity allows to optimize process parameters, for example, reduce temperature and pressure, leading to a lower energy consumption and cost.