Preliminary Risk Assessment for Storage and Handling of Highly Toxic Chemical in Rocket Industry

In solid propellant rocket motor manufacturing, many hazardous chemicals are handled. compared all other chemicals, Toluene di-isocyanate (TDI) is highly toxic with Threshold Limit Value (TLV-TWA) of 0.001 ppm (American Conference of Governmental Industrial Hygienists (ACGIH), in 2018 TLVs and BEIs. Threshold Limit Values for Chemical Substances and Physical Agents. Biological Exposure Indices. Cincinnati, OH, 2018, [1]) [American Conference of Governmental Industrial Hygienists (ACGIH)]. The exposure of TDI at process areas and storages to the working personnel mainly due to an inhalation of vapors. Long time exposure of TDI at above permissible exposure limit may cause lung damage and also reduce the lung function, which may become permanent. The International Agency for Research on Cancer (IARC) has classified TDI as the possible carcinogen in humans. Due to sensitisation property of TDI, the individuals who are sensitised to TDI may suffer from asthama even if exposed to lower than permissible exposure limit. Hence due to human health adversly effecting by TDI toxic effects, utmost care should be taken to avoid human exposure to TDI vapors due to spillage. For solid propellant processing, TDI is used as curator. TDI will be stored in barrels at storage areas and transferred to process area in suitable containers. Any major spillage/leakage in these barrels/containers may release toxic vapours and affect the working personnel. Preliminary Risk Assessment was conducted to determine the safe corridor/distance for TDI Storage areas. TDI spillage pool area, air borne quantity, evaporation rate and concentration level for storage area was computed using Dow’s Chemical Exposure Index and Hazard Distance and the same was compared using ALOHA software for the Acute Exposure Guideline Levels (AEGL) or Emergency Response Planning Guidelines (ERPG). Based on the above evaluation, safe distances were arrived for bulk storages of TDI. At the same time preventive risk control systems are adopted to mitigate the risks to the working personnel. With these results, it is found that by applying risk control measures the concentration is controlled and within the acceptable range.