Technique for Order Performance by Similarity to Ideal Solution (TOPSIS)-entropy Methodology for Inherent Safety Design Decision Making Tool

Abstract

Inherently Safer Design (ISD) concept has been recognized as a way to achieve safer operation and economically attractive for the process plant. However, the challenges in selecting between ISD alternatives are the need to satisfy conflicting objectives. Therefore, there is the need for a multi-criteria decision-making tool that can make a reliable, coherent and defensible decision. The objective of this paper is to illustrate the use of the TOPSIS-entropy method as a decision-making tool to evaluate the trade-off of ISD alternatives. Entropy method was included in TOPSIS calculation to remove the subjectivity problem during the weight scoring process for attributes. This methodology has been applied to identify the best ISD alternatives for methyl isocyanate storage at West Virginia fertilizer production plant. The results show that the rank obtained for ISD alternatives influenced by the weight value that indicate the priority given to the attributes. The Du Pont method has been identified as the best option when higher priority given to the attributes under external/regulatory pressure and the existing methodology with inventory reduction has been identified as the best option when higher priority given to the attributes under internal/cost pressure. The results obtained using TOPSIS-entropy method are congruent with the results reported in the previous work using Multi Attribute Utility Analysis proves that this method can be used to resolve ISD conflicts effectively. More than that, the capability of TOPSIS to deal with different types of weight estimation techniques gives an added value to this methodology.