QUANTITATIVE RISK ASSESSMENT (QRA)

An Overview

Risk Analysis is proven valuable as a management tool in assessing the overall safety performance of the Chemical/ fuels Process Industry. Although management systems such as engineering codes, checklists, and reviews by experienced engineers have provided substantial safety assurances, major incidents involving numerous casualties, injuries and significant damage can occur - as illustrated by recent world-scale catastrophes. Risk Analysis techniques provide advanced quantitative means to supplement other hazard identification, analysis, assessment, control and management methods to identify the potential for such incidents and to evaluate control strategies.

This study tries to quantify the risks to rank them accordingly based on their severity and probability. The report should be used to understand the significance of existing control measures and to follow the measures continuously. Wherever possible the additional risk control measures should be adopted to bring down the risk levels.

Software such as PHAST & PHAST RISK, EFFECTS, ALOHA are used to carry out the modelling of probable outcomes such as fire, explosion, vapour cloud explosion etc.

Objective

The methodology adopted in conducting Quantitative Risk Assessment in line with Scope of work for QRA. The main objective of conducting QRA is to:

• To give a description of the facility with respect to:
• To identify Major Accident Hazards mainly fire, explosion and toxic gas scenarios and the likely consequences & risk associated with these scenarios, based on review of the Project documents, Project significant risk criteria, existing QRA studies (if any), Process Flow Diagrams, Heat & Mass Balances and facility plot plans.
• To identify potential risk reduction measures on the basis of cost effective solutions to meet the required acceptable performance level (if they are found to be inadequate). To demonstrate ALARP.
• To eliminate or reduce to As Low As Reasonably Practical (ALARP) in terms of risk to human health, risk of injury, risk of damage to plant, equipment and environment, business interruption or loss etc.
• To suggest the adequate safe location for the upcoming design facility.