INVESTIGATION OF LARGE-MAGNITUDE INCIDENTS:
BHOPAL AS A CASE STUDY
Ashok S. Kalelkar
Arthur D. Little, Inc.
Cambridge, Massachusetts, USA
The Institution of Chemical Engineers Conference On
Preventing Major Chemical Accidents
The investigation of large-magnitude incidents is fraught with difficulties and the process of establishing the primary cause of an incident often requires an understanding of human nature in addition to the necessary technical and engineering skills. The salient non-technical features that are common to the investigation of large-magnitude events are discussed in general. The investigation of the Bhopal disaster is discussed as a specific case study in light of these salient features. The results of the overall investigation are discussed and it is demonstrated that the commonly-held view that water-washing of a certain header caused the disaster is physically impossible. Evidence is presented which indicates that direct water entry into the methyl isocyanate storage tank was the likely initiating cause of the Bhopal disaster.
In the aftermath of a major accident or incident in the chemical industry, it is common practice to ascertain the cause of the event through an investigation. If the magnitude of the incident is very large in terms of its impact on people, property, or the environment, it is not uncommon to assemble several teams of investigators to seek the cause of the incident independently. In the United States, a large-magnitude event may be investigated by the company that owns the facility, the insurance group that provides the liability coverage, federal investigators (e.g., OSHA, EPA), and state and local regulatory agencies. When several investigations are being conducted concurrently, in spite of the differing interests that are represented by each investigating team, cooperation and fact-sharing generally occurs among the investigating teams. This cooperative spirit was evident to some extent, for example, in the investigation of the LPG disaster in 1984 in Mexico City l.
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Bhopal as a Case Study - Union Carbide Corp.
Given the significant amount of damage that is typically associated with a large-magnitude event, coverage by the news media is both extensive and exhaustive, especially if a number of fatalities have occurred. The news media represent yet another group of separate investigators and tend to focus on the human interest aspects of the tragedy. In addition, often with little hard information available, they actively speculate on the cause of the event in an attempt to "scoop" the story; that is, to be the first to report the cause to the world at large. In recent years, the news media with their surfeit of investigative reporters have become a predictable presence at the site of an incident.
Although no two major disasters are the same, our involvement in the investigation of more than a dozen events of significant magnitude has led us to believe that there are certain salient features that are common to most investigations. They include: 1. Media Pressure - In the immediate aftermath of a large-magnitude incident, both nontechnical and technically trained reporters converge on the site, looking for quick "answers" to the question of what caused the event.
Most reporters are responsible, restrained, and unbiased in their reporting. However, a fringe group usually appears on-site that is more interested in developing causation theories, which seem to have great public appeal, regardless of their veracity. In the case of the disaster at Bhopal in 1984, the cause célèbre was the "missing slip-blind" during a water-washing operation. An assertion was made that failure to insert a slip-blind prior to water-washing of some filters ultimately led to water entering the MIC tank and starting a reaction. This assertion proved to be...