(39b) Development of a Thermal Radiation Dose Approach for Jet Fires

In the realm of process safety, there are areas that overlap with fire protection. One such subject matter is the determination of potential impacts to buildings, process equipment, or support structures in a fire scenario. Most attempts at fire impact are constrained to modeling a representative jet fire or pool fire with the assumption of a sustained duration and matching the thermal radiation levels and assumed exposure duration to a specific damage level. When modeling accidental releases of flammable materials, an analysis will find that many fire scenarios are transient and not well represented by a steady-state fire model. This is especially true for jet fires, which are pressure driven and whose size decays as the system pressure and inventory decay. To address this behavior, assumptions about the representative fire size and duration can be made. However, this is difficult to properly apply across a range of potential outcomes in a complex process plant. Furthermore, it is understood that the thermal radiation impacts to buildings, process equipment, or support structures are not neatly governed by a single fire radiation endpoint with a “prolonged” duration. The thermal radiation dose at the receptor is a better way to characterize potential damage. This paper outlines the initial work aimed at developing a dose calculation model for jet fires. The approach utilizes information from time-varying release modeling coupled with multiple instances of steady-state fire models to develop a prediction of thermal radiation dose at the receptor location.