Resolving inherently safer design conflicts with decision analysis and multi-attribute utility theory

The 1984 Bhopal tragedy involved the toxic and reactive chemical methyl isocyanate (MIC). The enormous human toll of this tragedy spurred the development of the concept of inherently safer design (ISD), and several published studies have since demonstrated the application of ISD concepts to the Bhopal process. In 2008, the U.S. Chemical Safety Board (CSB) investigated a fatal explosion at a chemical plant in West Virginia, for which a potential (unrealized) outcome was the loss-of-containment of the large inventory of MIC stored onsite.The CSB asked the National Academy of Sciences (NAS) to investigate the application of ISD concepts to the design of the West Virginia plant. The NAS study indicated that one of the primary difficulties in evaluating and choosing between ISD alternatives was the need to satisfy conflicting design objectives. The NAS panel suggested Multi-attribute utility theory (MAUT) as a basis for evaluating ISD alternatives, but they did not illustrate its use in this report.Here, we illustrate the use of MAUT as a decision analysis tool for evaluating ISD alternatives, and show that the MAUT technique is an effective tool for resolving ISD conflicts. We demonstrate how to use MAUT to evaluate ISD alternatives by formulating utility functions and weights for the decision objectives. We also examine how the final ranking of alternatives varies with the weights.