Potential Hazards Relating to Pyrolysis of c-C{sub 4}F{sub 8}O, n-C{sub 4}F{sub 10}, and c-C{sub 4}F{sub 8} in Selected Gaseous Diffusion Plant Operations

Trowbridge, L.D.

Oak Ridge National Laboratory

关键词: Welding;    Oxidation;    Oxygen;    Gaseous Diffusion Plants;    Pyrolysis;   

DOI  :  10.2172/814073
RP-ID  :  ORNL/TM-2000/68
RP-ID  :  AC05-00OR22725
RP-ID  :  814073

美国|英语

来源: UNT Digital Library

【 摘 要 】

As part of a program intended to replace the present evaporative coolant at the gaseous diffusion plants (GDPs) with a non-ozone-depleting alternate, a series of investigations of the suitability of candidate substitutes is under way. This report summarizes studies directed at estimating the chemical and thermal stability of three candidate coolants, c-C{sub 4}F{sub 8}, n-C{sub 4}F{sub 10}, and c-C{sub 4}F{sub 8}O, in a few specific environments to be found in gaseous diffusion plant operations. One issue concerning the new coolants is the possibility that they might produce the highly toxic compound perfluoroisobutylene (PFIB) in high-temperature environments. Two specific high-temperature thermal environments are examined, namely the use of a flame test for the presence of coolant vapors and welding in the presence of coolant vapors. A second issue relates to the thermal or chemical decomposition of the coolants in the gaseous diffusion process environment. The primary purpose of the study was to develop and evaluate available data to provide information that will allow the technical and industrial hygiene staff at the GDPs to perform appropriate safety evaluations and to determine the need for field testing or experimental work. The scope of this study included a literature search and an evaluation of the information developed therefrom. Part of that evaluation consists of chemical kinetics modeling of coolant decomposition in the two operational environments. The general conclusions are that PFIB formation is unlikely in either situation but that it cannot be ruled out completely under extreme conditions. The presence of oxygen, moisture, and combustion products will tend to lead to the formation of CF{sub 4} and oxidation products (COF{sub 2}, CO, CO{sub 2}, and HF) rather than PFIB.