RADIATIVE HEAT FLUX ZONE OF INFLUENCE FOR OPEN FIRES AND ELECTRICAL ENCLOSURE FIRES

摘要

For targets exposed to the radiant heat from a firethe typical approach used in Fire PRA is to useengineering correlations such as those contained inNUREG-1805. Those correlations are based ontechniques developed for large, outdoor, hydrocarbonfires (tank farms, pipeline rupture, etc.). There are twoshortcomings with this approach. The first is theapproach uses correlation for the emissive power of a firethat does not reflect the real-world behavior typical PRAignition sources other than fires like a catastrophicfailure of the turbine lube oil system. This results inoverly conservative estimates of the zone of influence(ZOI) of a fire, the distance at which a fire can causedamage to target. The second shortcoming is that there isno specific guidance on how to evaluate the ZOI when thefire is inside of an electrical cabinet (EC) and the targetis outside of the enclosure. As a result, these fires aretypically treated as if they were not enclosed in an ECand that the target can see the flame volume.To address these shortcomings, the Electric PowerResearch Institute (EPRI) has sponsored research intodeveloping improved approaches for determining for theradiative heat flux ZOI for open fires and fires in ECs. Amodified open fire approach was derived from the basicprinciples of fire dynamics and validated against testdata. An approach for fires in ECs was developed bymodeling EC fires with the Fire Dynamics Simulator(FDS), a computational fluid dynamics (CFD) model forfire. The FDS modeling approach was validated usingfull-scale test data of fire in ECs. Modeling results wereused to develop approaches for both ZOI and severityfactor (SF), the fraction of expected fires capable ofcausing damage. This paper will provide a summary ofresearch activities and summarize the new approaches.