(64b) Using Time-Varying QRA to Evaluate Hazards during a Turnaround or Temporary Operations

During turnarounds or other simultaneous operations (SIMOPS), the risk of process incidents due to abnormal operations may be increased, at the same time that the number of workers in the plant and temporary shelter locations is also increased. A facility siting study (FSS) or QRA is often developed to assess the normal risk profile of a facility, but it is not adequate to evaluate the dynamic risk profile during these periods. These studies lack the ability to quantitatively assess the risk as it changes throughout ongoing operations, but they can be leveraged to develop a dynamic risk model to assess these temporary operations.

This paper identifies the issues facing operators during these temporary operations and presents a methodology developed by AcuTech for performing a time-varying quantitative risk assessment (QRA) to support safe operations during turnarounds and other abnormal operations. This paper will present methods to perform a dynamic QRA, develop usable results, and implement effective safety measures to increase turnaround flexibility, optimize SIMOPS, and protect workers.

The paper will demonstrate the application of this methodology using a practical case study. This case study demonstrates the application of a detailed, quantitative analysis for siting contractors and other onsite populations during a large-scale turnaround operation at a facility. The case study illustrates the methodology, presentation of results, and development of practical risked-based recommendations to protect workers.