MULTI-POINT FIRE ANALYSIS AND SIMPLIFIED FIRE MODELING FOR FIRE RISK QUANTIFICATION

摘要

This paper discusses multi-point fire analysis and the use of simplified fire modeling techniques for fire risk quantification. The theory, practical aspects of implementation, sample results, and insights from application of these techniques to the Shearon Harris Fire PRA are discussed. Multi-point fire analysis is a requirement of the ANS Fire PRA Standard for Capability Category II [Reference 1]. While a single point fire analysis applies one calculated CCDP to the entire heat release rate distribution of a particular ignition source, a multi-point analysis calculates CCDPs for multiple fire sizes and applies severity factors corresponding to each of those heat release rates. The paper presents a comparison of calculated CDFs from single-point and multipoint calculations, as well as a discussion of how to optimize CDF realism with this technique. Simplified fire modeling techniques to calculate time to cable damage and time to hot gas layer are also presented. These two parameters are required to calculate non-suppression probabilities. Time to cable damage is calculated using Heskestad's plume correlation in concert with fire growth curves. Time to hot gas layer is calculated using the MQH correlation, a scaling expression, and fire growth curves for each ignition source bin with several stacked cable tray (i.e., secondary combustible) configurations. These techniques are easily automated for application to thousands of ignition sources, targets, and compartment configurations.