Chapter 7 - Quantitative Risk Assessment: Computer Modeling, Uses in Setting Buffer Zones, Strengths and Limitations, Uses and Abuses

Abstract

This chapter describes the quantitative risk assessment through computer modeling to generate contours of risk as an aid to risk management. Quantitative risk assessments are used to determine buffer zones around process plants. The chapter outlines the structure of a very basic computer program for the calculation of risks from fire and explosion and explains the two main steps in calculating risks directly from a process flowsheet. The various bases on which separation distances can be set rationally: “worst possible” incident consequences, “worst credible” incident consequences, and risk, are also discussed. The chapter summarizes the strengths and limitations of quantitative risk assessment. It reviews the safety of existing plants that handle or store significant quantities of hazardous materials. It surveys the plants and operations to determine whether the safety precautions are adequate for the inherent hazards. The faults in the application of hazard analysis and risk management are also covered in the chapter.