Abstract:
The accidental release of toxic, flammable and hazardous chemicals from chemical plants are
causing serious threats to lives, properties and environment. The situation becomes more
damaging if the plant is located in a densely populated area. Different chemicals are used for
the production of variety of chemical products. Among all these, extreme use of chlorine gas
in the manufacturing of chemicals and products possess great risk of chlorine gas leakage
from storage tank. Chlorine gas is irritating to eyes and it cause respiratory problems on
inhalation and being denser than air it remains on the ground for long time. During sudden
release the gas will disperse in the atmosphere depending on the process and meteorological
conditions prevailing at that time. In this paper with the help of ALOHA model the areas of
Bhagwanpur (Uttarakhand) and Durgapur (West Bengal) which can be affected during the
dispersion of chlorine gas have been calculated. It is mainly based on the principles of fluid
dynamics. The methodology discussed in this paper is useful to predict the probable threat
zones of chlorine gas dispersion for the concentrations 350 ppm, 125 ppm, and 15 ppm
during summer, monsoon, post monsoon and winter season for the two areas. The rate of
maximum indoor and outdoor concentration of chlorine gas in terms of time from the source
at a distance of 2 km is also calculated. With the help probit analysis mortality rate for the
three concentrations are calculated. The situation can be very critical during winter and post
monsoon season. The mortality rate is also a matter of concern as it indicates 49.20 % of
mortality rate for 350 ppm concentration for an exposure period of 15 minutes. The results
from the scenarios are further analyzed and compared for the same and can be used in the
analysis of consequences and risk assessments by the respective sectors in order to minimize
the potential impact from such incident in future.
