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Analysis of BHOPAL Plant Gas Tragedy

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This research paper introduces the Bhopal plant gas tragedy disaster that happened in India, 1984:
- Major causes and errors leading to multiple failures of the chemical plant are elaborated.
- Main catastrophic consequences are discussed and classified in terms of casualties and fatalities, acute and chronic health effects, and toxic effects on soil and water.
- Rehabilitation procedures adopted after the incident.
- Preventive barriers that could have been adopted in order to reduce the likelihood of the disaster occurrence.
If accidents are to be reduced, this needs maximum attention and an optimum risk management system.

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Analysis of BHOPAL Plant Gas Tragedy

  1. 1. Holy Spirit University of Kaslik - USEK Faculty of Engineering Department of Chemical Engineering Analysis of BHOPAL Plant Gas Tragedy Rita EL KHOURY Jean Noel SEMAAN Maya HARB Project Supervisor Date Dr. Rachad RAFEH Fall 2017-2018 Submitted on: 1 December 2017
  2. 2. 2 ACKNOWLEDGEMENT First and foremost, we offer our deep sense of gratitude to all those who believed in us and supported us throughout our educational years. We greatly appreciate all the assistance, inspiration and encouragement that we got during our academic year that we feel so fortunate to spending it at Holy Spirit University of Kaslik. Afterward, we would like to express our sincere appreciation to Dr. Rachad RAFEH for giving us the opportunity to write this report about the industrial disaster that occurred at the Union Carbide pesticide plant in Bhopal, India. We are deeply glad and thankful for their valuable guidance and for sharing their wisdom and expertise with us. It was a priceless time to search, learn many new things and gain more knowledge. Last but not least, we would like to thank everyone who helped us in a way or another to finalize this project.
  3. 3. 3 ABSTRACT At first, this paper introduces the Bhopal gas tragedy disaster that happened in India, 1984. Then, the major causes and errors leading to multiple failures of the chemical plant are elaborated. Furthermore, the main and catastrophic consequences are discussed and classified in terms of casualties and fatalities, acute and chronic health effects, and toxic effects on soil and water. This report shed lights also on the rehabilitation procedures adopted after the incident along with the preventive barriers that could have been adopted in order to reduce the likelihood of disaster occurrence. If accidents are to be reduced, this needs maximum attention and an optimum risk management system. Key words: gas tragedy, failures, barriers, risk management.
  4. 4. 4 Table of contents ACKNOWLEDGEMENT........................................................................................................... 2 ABSTRACT................................................................................................................................... 3 Table of contents........................................................................................................................... 4 List of tables................................................................................................................................... 5 List of figures................................................................................................................................. 6 1. Introduction.............................................................................................................................. 7 2. Initiating Causes ...................................................................................................................... 8 3. Consequences..........................................................................................................................10 3.1 Effects on Human Health:............................................................................................10 3.2 Compensation and Legal Aspects: ............................................................................11 3.3 Soil and Water Contamination...................................................................................12 3.3.1 Soil Contamination....................................................................................................12 3.3.2 Ground Water Contamination................................................................................14 4. Rehabilitation Procedures....................................................................................................16 5. Preventive and Mitigation Controls....................................................................................17 6. Conclusion...............................................................................................................................18 REFERENCES............................................................................................................................19
  5. 5. 5 List of tables Table 1 : Analysis of causes of failure ................................................................................... 9 Table 2 : Analysis of contaminants in different samples ...................................................... 15
  6. 6. 6 List of figures Figure 1 : Initiating cause of Bhopal disaster......................................................................... 9 Figure 2 : The released gas cloud ........................................................................................ 11 Figure 1 : Bhopal plant after the disaster ............................................................................. 11
  7. 7. 7 1. Introduction Management of hazards is becoming a crucial need in order to reduce the frequent occurrence of major disasters such as Bhopal, Chernobyl, Mexico gas explosion, etc. A disaster is a result from the combination of hazard, vulnerability, and insufficient measures to reduce the potential chances of risk. The Bhopal accident was amongst the worst industrial disasters of its time. The disaster occurred on the night of December 2, 1984 at the Union Carbide India Limited pesticide plant in Bhopal, India. In the manufacturing process of this plant, methyl isocyanate reacts with naphtol to produce carbaryl pesticides. Also, many chemical compounds were manufactured in this plant such as phosgene, mono methylamine, and methyl isocyanate. Despite that the plant was located near the residential areas and close to the Bhopal railway bus stand, in 1979 the government gave the license to produce 5000 tons of carbaryl based pesticides in the existing premises. The production achieved between 1981 and 1983 decreased from 2704 tons to 1657 tons due to the reduction in demand for the pesticides as the import of new products increased. Hence, the sales declined and the unit was not making a profit anymore. Many technicians left to take up new positions elsewhere which led to poor safety and maintenance practices. On the night of December 2, 1984, a leak of at least 30 tons of highly toxic gases, methyl isocyanate gas and other chemicals, from the tank into the atmosphere resulted in the exposure of thousands of people. This report will shed lights on the series of events and the multiple threats that caused the occurrence of this accident. Also, the consequences of this incident will be elaborated along with the effects on human health, and the toxic materials found in soil and water. This paper is an attempt to drive lessons for a better industrial risk management.
  8. 8. 8 2. Initiating Causes First, a brief description of the manufacturing facility will be given so that the sequence of events becomes clearer. The major chemical compound, MIC (methyl isocyanate), is stored in underground stainless steel tanks. The tanks must be kept refrigerated so that the temperature of storage is kept close to 0°C. Behind the tanks there is vent gas scrubber used to neutralize the MIC in case of release. Then, there is a flare tower to burn the remaining gases exiting the vent gas scrubber. Based on the safety manual, the scrubber should be kept in active mode as long as the plant is operating. The routine release of gases goes through the process vent header PVH, a line connected to the nitrogen pressurization system, to the vent gas scrubber. In October 1984, in order to reduce operating costs, it was decided to keep the vent gas scrubber in passive mode and to shut down the refrigeration plant against safety manual instructions. In December, as part of pipes cleaning procedure, the plant supervisor ordered washing the MIC lines assuming that there was a blockage. The operator began washing out four lines in the MIC storage area, and all these were connected to the PVH. While water was being pumped under high pressure, he found that some lines were clogged. He reported the problem to the supervisor. The supervisor, who was transferred from a completely different plant to this unit only two weeks before the event, gave further instructions for rewashing and inserting a slip blind so that water won’t go into the MIC tank. However, water accumulated at height of 20 feet during the earlier washing and entered the tank containing 40 tons of MIC. The absence of using a slip bind first is the triggering event. Due to water entry, an exothermic reaction occurred which increased the temperature inside the tank to over 200 ͦ C and raised the pressure. About 30 metric tons of MIC escaped from the tank into the atmosphere and toxic gases covered more areas in a shorter period of time. The safety valves burst due to the increase in pressure and the flare tower and the scrubber vent gas were out of service for five months as illustrated in figure 1. As mentioned earlier, the refrigeration is switched off to save money which helped in the increase in temperature.
  9. 9. 9 Figure 1: Initiating cause of Bhopal disaster Several other causes of failure contributed in this gas leakage are represented in table 1. Type of Failure Basic Causes Technical - Design failure and poor maintenance - Absence of HAZOP studies Operator - Poor personnel and training - Over stress - Poor communication between shifts Management - Poor risk assessment practices - Lack of formalization - Failure to anticipate the catastrophic potential Government - Absence of clear policy and regulations - Lack of controlling land use Table 1: Analysis of causes of failure
  10. 10. 10 3. Consequences The pesticide plant was surrounded by houses and towns, leading to more than 600,000 people being exposed to the deadly gas cloud that night. The dense gas cloud contained phosgene, hydrogen cyanide, carbon monoxide, hydrogen chloride, oxides of nitrogen, carbon dioxide, etc. The gases stayed low to the ground, causing victims throats and eyes to burn, inducing nausea, and many deaths. A government official declaration in 2006 stated that the leak caused 558,125 injuries including 38,478 temporary partial injuries and approximately 3,900 severely and permanently disabling injuries. Estimates of the death toll vary from as few as 3,800 to as many as 16,000, but government figures refer to an estimate of 15,000 killed over the years. The toxic substance spread its way in and around the neighborhood located near the plant causing up to 10,000 deaths in first three days and thousands of animals perished in the disaster as well, poisoned by the huge gas leak. The wide variety of symptoms observed at Bhopal has been due to the exposure of a large number of toxic substances in varying concentrations at different locations. Human rights groups say that thousands of tons of hazardous waste remain buried underground, and the government has conceded the area as contaminated. Many of those who were exposed to the gas have given birth to physically and mentally disabled children. For decades, survivors have been fighting to have the site cleaned up. However, there has been no long-term epidemiological research which conclusively proves that birth defects are directly related to the drinking of the contaminated water. 3.1 Effects on Human Health:  Acute, short term health effects: - Respiratory Disorders: irritation to the lungs, causing coughing and/or shortness of breathing, burning in the respiratory tract. - Vomiting and stomach pain. - Severe eye irritation and blindness. - Feeling of suffocation
  11. 11. 11  Chronic, long term health effects: - Reproductive system: It may damage the growing fetus. Also affect fertility in men and women. - Effect traces of many toxins were found in the Brest Milk of mothers and were in turn transmitted to the recipient babies. - Immune and neurological disorders. - Cardiac system failure. 3.2 Compensation and Legal Aspects: - Compensation of $470 millions: around $500 per dead - Twenty years of passiveness. - Case was reviewed and put up in American Court. - In order to provide safe drinking water to the population around the factory, the government put a scheme for treatment and improvement of water supply. - Supreme Court was directed to take immediate steps for disposal of toxic waste lying around and inside the factory. Figure 2: the released gas cloud Figure 3: Bhopal plant after the disaster
  12. 12. 12 3.3 Soil and Water Contamination Soil and ground water were also contaminated by several toxic substances such as heavy metals and chlorines at various degrees. SHRI CHAUHAN, a former employee of Union Carbide and currently with District's Industrial Area Dept, says that: “in the compound of the UCL, about 25 chemicals and hazardous wastes lying in there. They are Methyl Isocyanate, Methyl Chloride, Carbon Tetra chloride, Methanol, Phosgene, Chlorine, Tar coal, Mercury, Naphthalene and many more.” 3.3.1 Soil Contamination Nickel, Chromium, Mercury and Lead were found in soil samples taken from different areas of the plant. The tests showed that Nickel and Chromium were the most found heavy metals in the samples taken. On the other hand, Mercury was mostly found in the alpha- naphthol and the Pan Filter sites. These metals caused several toxicological effects, as presented below:  Nickel: - Metallic Ni and its alloys are designated as carcinogens. - Nickel refining plant workers are present to a higher risk of lung cancer than normal people. - Women exposed to Ni, may be at complicated pregnancy risk and even leading to birth defects and malformations e.g. cardiovascular and musculoskeletal. - Chronic and long term Ni exposure can lead to chronic bronchitis and lungs malfunction. 50g/L is the maximum acceptable Nickel dosage for human consumption, as set by the European Union directive.  Chromium: - It is corrosive and considered as allergen (skin allergies). - Chromium’s long term exposure leads to lung cancer 50g/L is the maximum acceptable Chromium dosage for human consumption, as set by the European Union directive.
  13. 13. 13  Mercury: - Mercury is very toxic and dangerous. - There are no removal ways of mercury once it penetrated the human body. - Hg affects the function of the kidneys causing renal damage. - Chronic and long term Hg exposure may disturb the nervous system leading to tremors, spasms, loss of memory and depression. 1g/L is the maximum acceptable Chromium dosage for human consumption, as set by the European Union directive.  Lead: - Lead, when ingested can harm the human body. - Lead causes hypertension, as well as neurotoxicity. On the other hand, a significant amount of pesticides were found in soil samples. HCH pesticide concentrations were 9 mg/Kg in the soil samples taken and their average concentration was 1.60 ppm. HCH presents two forms of isomers: gamma- HCH and beta- HCH. Gamma’s form dosage exceeded Beta’s. The HCH pesticides different consequences on the human body were several: - Humans are considered sinks for these toxic chemicals, because they rank as the highest level. - HCH gets bio-concentrated when ingested, especially in infants and breast milk. - It presents toxic effects on fertility and reproductive system. - It can lead to lung, liver and endocrine cancers. Furthermore, the investigations showed that Volatile Organic Compounds such as Dichlorobenzene, 1, 3, 5-Trichlorobenzene and Tetra ChloroBenzene were present in all the samples. The predominant contaminant was the Dichlorobenzene. The total dose found in the soil was 5.86 mg/Kg and its mean was to some extent lesser than 1 mg/Kg. Every soil sample tested in the plant revealed positive results.
  14. 14. 14 Those compounds are considered as toxic substances, because they induce several problems:  Dichlorobenzene: - It enters the human body by inhalation. - It causes: depression, headache, anorexia, liver atrophy, eye irritation, etc.  1,3,5-Trichlorobezene: - It enters the body by inhalation. - It damages the liver, kidneys as well as the thyroid.  Tetra ChloroBenzene: - The exposure of TCB is done through food. - It damages the liver, kidneys as well as the thyroid. - Chronic exposure to TCB leads to chromosomal aberrations. 3.3.2 Ground Water Contamination Similarly to the soil, ground water was also found to be contaminated by different toxic chemicals: - Heavy Metals: Nickel was the principal contaminant among all ten ground water samples, presenting a value of 1.0990 ppm. - Pesticide HCH HCH found in the ground water samples was 0.0898 mg/L, having a mean value of 0.011 ppm. The water tested from the factory premises showed 0.115 mg/Kg of the pesticide HCH. The level of pesticides found in the factory’s premises is ten times greater than those found are in the residential areas around the plant.
  15. 15. 15 - Volatile Organic Compounds: The average doses in ground water samples of the residential areas were found to be 0.050 mg/Kg; however the samples from the plant premises contained 0.0331 mg/L of volatile organic compounds. - Halo-organics: Dichloromethane and Chloroform were found in all eight ground water samples taken. Dichloromethane concentration values were two times higher than Chloroform. Table 2: Analysis of contaminants in different samples The soil and ground water of residential areas, the factory, the vegetables and the breast milk were highly affected by this disaster to various degrees. The vegetables grown in the interior of a residential area opposite to the front gate of the factory had the ability to absorb these toxic chemicals and transfer to the next level of a food chain. Although evaporation ponds were present to collect chemical wastes, the possibility of overflowing during rainfall and contaminating surrounding areas was high.
  16. 16. 16 4. Rehabilitation Procedures  Occupational rehabilitation: 33 of the 50 planned work sheds for gas victims started. It is estimated that 50,000 person need alternative jobs and less than 100 gas victims have found regular employment under the government scheme.  Habitation rehabilitation: 2,486 flats in two and four buildings were constructed outside Bhopal; however water did not reach the upper floors. In order to provide safe drinking water to the population, there was a system for improvement of water supply. Infrastructures were missing for at least a decade.  Environmental rehabilitation: When the factory was closed, pipes, drums and tanks were sold. Isolation material was falling down and spreading. The area around the plant was used as a dumping area for hazardous chemicals. Formal statements were issued that air, water, vegetation and foodstuffs were safe within the city. At the same time, people were informed that poultry was unaffected, but were warned not to consume fish.  Health care: In the immediate aftermath of the disaster, the health care system became tremendously overloaded. Within weeks, the State Government established a number of hospitals, clinics and mobile units in the gas affected area. In 1994, there were approximately 1.25 beds per 1000, compared to the recommendation of the World Bank of 1 bed per 1000 in developing countries.
  17. 17. 17 5. Preventive and Mitigation Controls The most critical reasons for the occurrence of the errors are the corporate level failure of safety management systems and procedures. If regular rehearsal of emergency procedures had been in force in Bhopal, many of the plant equipments and operator inadequacies could have been corrected. Analysis of the Bhopal accident shows that organizational failures are the most critical ones that need attention if accidents are to be avoided. In order to reduce the likelihood of the incident, some preventive barriers could have been adopted: - Supervisors could have been placed on night shifts. - The readings and feedback of equipments could have been taken for every one hour. - There should have been 4 stage backup systems instead of a one manual backup system. - Proper maintenance and servicing of flare towers, pressure valves, and gas scrubber must have been made. - Strict regulations and methods must have been used according to the manual - Proper pressure gauges should have been used to maximize the safety. - Formulation of a detailed HAZOP or HAZAN study on the completed installations by internal staff and it should be used for safety management of day-to-day operations. Such work has to be done by the people who are directly involved with the plant as only they are likely to have the detailed knowledge required based on work experience.
  18. 18. 18 6. Conclusion It is essential that decision makers perceive and estimate the hazards arising out of a project at the project formulation phase. Risk management has to start at the site selection and project feasibility analysis phase. This comprehensive approach is the only way to have cheaper and safer plants. Thinking about the hazards after the commissioning of the project is likely to minimize the extent of hazards whereas the anticipate-and-prevent approach is likely to provide minimum cost options, if initiated at the project formulation phase itself. A conceptual framework for accident analysis indicates that in most complex systems 80 to 85% of the failures are in the management and organization aspects of the system and only 15-20% of the failures are due to human error. The analysis of the Bhopal accident, presented here corroborates the conclusion that organizational or corporate level failures are the most critical ones that need attention if accidents are to be avoided. The most important prerequisite for accident prevention is the top management commitment to safety. Accident prevention needs not to be treated as an expensive add-on facility but it has to be an integral part of management and organizational objectives. When hazardous facilities are to be built in developing countries, the levels of safety to be achieved must be higher. To sum up, risk management has to be started along with the preparation of the feasibility report as an inherent part of the project appraisal procedure, for all hazardous chemical facilities. This has to be put into operation along with the running of the plants through detailed safety management practices supported by appropriate corporate safety commitment.
  19. 19. 19 REFERENCES [1] B. Bowonder, “An analysis of the Bhopal accident,” Project Appraisal, 2:3,157-168, (1987). [2] SRISHTI, “Surviving Bhopal, toxic present-toxic future”, report on human and environmental chemical contamination around the Bhopal disaster site, January 2002. [3] Yusuf S.A., “Bhopal gas tragedy”, Saint Philomena’s college,

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