The Fire Science Group of the Hazards Control Department. Lawrence Livermore Laboratory has been asked to design a probable fire scenario for a fuel-pellet fabrica tion facility. Using this model we were to estimate the potential for thermal damage to the final HEPA filters. These filters would not experience direct fire exposure because they are the last component of the ventilation system before the exhaust air pumps. However. thc> would be exposed to hot air and fire gases that are drawn

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... the ventilation system. Because fire is one of the few occurrences that can defeat the containment integrity o\ facilities where radioactive materials are stored and processed, the fire scenarios must be defined to ensure that containment systems are adequate to meet the threat of such events. Fire-grow'th calculations are based on the measured fuel load of materials within the fabrication enclosure and on semi-empirical fire-spread models. We assume that the fire never becomes ventilation controlled. The temperature rise of ceiling gases and heat transfer from ventilation ducting are calculated using accepted empirical relationships, and the analysis shows thai even under the most severe exposure-conditions, heat transfer from the duel reduces the fire gas temperatures to levels that would not hamper filler function.