Modeling downwind hazards after an accidental release of chlorine trifluoride Page: 5 of 17
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The second sequence, excess water vapor is described by the following reactions:
4C1F3 + 6H20 -+ 2C102 + 2C120 + '/02 + 12HF (3a)
C120 + H20 - 2HOC (3b)
Adding these reactions yields the overall reaction under the conditions of excess water vapor:
4C1F3 + 7H20 2C102+ 2 HOCI +'/202 + 12HF (3c)
The reaction products for Equation 3c exhibit slow kinetics and are considered stable. The heat of reaction
for excess H20 was calculated to be 228.0 kJ/mole.
A review of the open literature (M. D. Cheng, Oak Ridge National Laboratory, Memorandum to Ken Keith,
Oak Ridge K-25 Plant, and Don Lee, Oak Ridge National Laboratory, January 10, 1994) found that ClF3
reactions with species other than water vapor may occur during normal atmospheric conditions. Axworthy et
al.' found that CIF3 was photochemically decomposed by ultraviolet radiation in the 200-350 nm wavelength
range leading to the formation of ClF20. However, protons of these wavelengths are relatively sparse in the
lower atmosphere where a release of CIF3 is likely to occur; therefore, this reaction mechanism would occur
much less frequently than hydration reactions. Blauer et al.8 documented thermal decomposition of CF3 and
CIF, in the temperature range of 530 to 1030*C, which is well outside the temperature experienced in the
lower atmosphere. Christie? described the reaction mechanism between chlorine compounds (including CIF,
CIF3, ClF,, and C102) and hydroxyl compounds in the condensed phase. These reactions only would be
relevant if CIF3 releases occurred during rain or fog events. Only then could ClF3 be incorporated into the
aqueous phase. Based on the literature review, the authors concluded that hydration reactions of CIF3 are
clearly the dominant mechanism to be considered for atmospheric releases (i.e., those reactions described by
Equations 2e and 3c).
For Equations 2e and 3c, the reaction rate under turbulent conditions follows the single-step reaction formula
developed by Varma et al10 and Varma:"
a + SP -) products (4)
where S is the number of moles of species p that reacts with one mole of species a (i.e., S is the
stoichiometric constant). Based on this single step reaction, the reaction rate R (mole/s2), adopted by Bloom
et al. for use in PLUME89A, is expressed as:
R=A / MW S)_ (5)
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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/m1/5/: accessed October 20, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.