The Impacts of Ignition Source Assumptions on Quantitative Risk Assessments

The evaluation of ignition sources in a Quantitative Risk Assessment (QRA) plays a critical role in obtaining accurate and meaningful results as their properties effect the likelihood and severity of events. There are several ignition source models (sometimes used in conjunction) created to assist in this process. Significant effort has been put in to improving and validating these approaches, but there are still a large number of parameters that must be defined by expert judgement or estimated based on incomplete data. The time required to assess and review the relevant parameters for many ignition sources can add unnecessary delay to the QRA.

Performing multiple risk assessments of a simulated, uniform facility using different ignition source models, can reveal how sensitive the end risk result is to the ignition source parameters chosen. In this way, time and resources can be reserved for the “high impact” parameters during a QRA. Additionally, this could help direct future efforts to refine the ignition source regimes. This paper walks through the ignition source parameter selection and evaluation and discusses the elements which were found to have significant impact.

While reducing uncertainties during a QRA helps ensure a high level of quality, there are diminishing returns at different points for different parameters. Knowing which parameters are the most pertinent can help a company focus their efforts on efficiently addressing these aspects of the QRA.