Modeling downwind hazards after an accidental release of chlorine trifluoride Page: 3 of 17
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Chlorine trifluoride (CIF3) is a chemical compound used in the gaseous diffusion process to enrich uranium at
two plants, one in Portsmouth, Ohio (PORTS) and the other in Paducah, Kentucky (PGDP). This compound
is employed in gaseous diffusion to fluorinate uranium yellow cake (U30,). CIF3 is shipped to the two
gaseous diffusion plants as compressed liquid in cylinders. These cylinders are stored on-site until they are
emptied into large storage tanks that hold about 57 m3 of compressed CIF3 liquid. An accidental breach of a
CIF3 storage cylinder or tank would result in a release of CIF3 vapor to the atmosphere, which is a concern
for plant managers and safety engineers because of its extreme toxicity. Many atmospheric dispersion models
are available to model the release of inert airborne contaminants; however, CIF3 is highly reactive with water
vapor in the atmosphere, and therefore, these models would not accurately predict atmospheric
concentrations of CIF3 downwind of a potential release. Additionally, these models do not predict the
formation of reaction products that also are toxic [i.e., hydrogen fluoride (HF) and chlorine dioxide (C102)].
Therefore, a more robust method of predicting downwind atmospheric concentrations of CF3 and its
reactions products is needed to assess potential release hazards. This paper discusses the development of a
chemistry and thermodynamics module that has been integrated into the dense gas dispersion model,
CHARACTERISTICS AND TOXICITY OF CIF3 AND PRIMARY REACTION PRODUCTS
CIF3 is a colorless gas, pale yellow liquid, and white solid. It has a slightly sweet, pungent, and irritating odor.
At 20*C, ClF, has a specific gravity about three times denser than air, and is volatile at normal atmospheric
pressure. CIF3 is classified as a dense gas and if released into the atmosphere will tend to "hug" the ground as
it moves downwind. ClF3 is the most reactive of the halogen fluorides, reacting with nearly all inorganic and
organic compounds, and violently with water. Table 1 shows some physical properties of CIF3, as well as its
primary atmospheric reaction products, HF and C102.
Due to its high reactivity, ClF3 is irritating and corrosive to all living tissues. Exposure to skin tissue causes
burns and lesions due to formation of hydrofluoric acid. CIF3 exposure to the eye causes damage that may
result in blindness. Burn activity continues while residual fluorides remain on the skin and eye tissue. If CIF3
is inhaled, it can cause inflammation of the respiratory tract and abnormal, potentially fatal, buildup of fluids
in the lungs. Due to its high toxicity, the Occupational Safety and Health Administration (OSHA) has
established strict regulatory limits on permissible air concentrations of CIF, (Table 1).
Anhydrous HF (i.e., HF free from water) is a liquid that readily volatilizes into a colorless gas with a strong,
irritating odor. At normal atmospheric pressures, HF vapor is assumed to exist as an equilibrium mixture of
the monomer (HF),, trimer (HF)3, hexamer (HF)6, octamer (HF),, and HF-H20.2 C102 is a yellow to red gas
or a red-brown liquid (below 11 *C) with an unpleasant odor similar to chlorine or nitric acid.3 Both HF and
CO2 are highly toxic with strict limits imposed on permissible air concentrations specified by OSHA to
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Lombardi, D.A. & Cheng, Meng-Dawn. Modeling downwind hazards after an accidental release of chlorine trifluoride, article, May 1, 1996; Tennessee. (digital.library.unt.edu/ark:/67531/metadc670261/m1/3/: accessed October 20, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.