The inhabitants of five villages around the LG plant from which styrene gas leaked on Thursday leading to the death of 11 people should be careful and should avoid low-lying areas as the gas – which is three times denser than air – may still be present, an expert has said. The authorities are planning to allow 1,500 people living in the vicinity of the plant in RR Venkatapuram, Visakhapatnamin, who were evacuated in the aftermath of the tragedy to go back to their homes.
Once such a mishap happens, it is entirely up to the mother nature to take care of it. Weather conditions of the area would play a major role in getting the gas diluted. So there is a need to check whether the toxic gas is present in the environment, said Rahul Raman, a Principal Engineer with Chennai-based Kaypear Consulting, who specialises in taming catastrophic release of toxic and explosive chemicals.
“Nobody should go there within 1 kilometre unless the area is evaluated and found safe, till then anybody going there should be wearing protective gear. People living beyond a one-kilometre radius of the plant too stay inside homes as the concentration of the gas is much lower inside the houses,” said Raman. Besides, The gas could probably be lingering in stormwater drains, and those people who are entering the drains should have proper gear as the exposure could be lethal, he added.
The authorities have still not pinpointed what has actually happened in the plant that led to the leak of styrene gas, which is used for making a polymer, polysterene.
Raman, who is a member of Design Institute of Emergency Relief Systems, a sub-organisation of the American Institute of Chemical Engineers, said however advances several possible scenarios.
According to him, such a runaway reaction cannot be an instantaneous one, and something might have happened at least 24-36 hours before the leak occurred. Since styrene is a highly reactive chemical, its reaction needs to controlled. This is done usually by adding an inhibitor. But when the concentration of the inhibitor falls, the runaway reaction is possible.
The second reason could be there was that the recirculation system that keeps styrene under a particular temperature was not working. The fluid is generally taken out of the vessel and cooled and put back into the container in the normal process. The preliminary report submitted by the company – LG Polymers India Limited – to the district authorities also pointed to a malfunctioning of the refrigeration system.
It is possible that there was a build-up temperature that has happened inside the tank. “ But the reaction leading to the leak might have commenced quite some time back, and the plant operators may have overlooked it,” he said.