Numerical simulation of pool fire in a forced ventilated enclosure

Forced ventilated compartment or enclosure is a configuration observed in nuclear reactor buildings, fuel fabrication and spent-fuel reprocessing units. Recognizing the safety implications during fire within such units, a study is performed to numerically simulate a pool fire scenario with an intention to address the outcome of fire-spread in a forced ventilated enclosure. The configuration considered here is broadly representative of a spent-fuel reprocessing unit. The influence of ventilation system operation on the development and spread of fire is assessed thoroughly. Fire sourced by a typical solvent predominantly used in the above unit is postulated. After the initiation of fire, its control is simulated by employing forced ventilation devices, which include sequential operation of fans and isolation valves in the system. The numerical simulations are performed using a CFD code called Fire Dynamics Simulator (FDS), developed by the National Institute of Standards and Technology, USA [1]. The simulation compares the enclosure fire behaviour for different operating conditions and highlights their influence on heat release rate (HRR), fire duration, fuel mass loss rate, ventilation flow rates, enclosure oxygen depletion rate, and pressure and temperature transients. This paper shows the importance of adopting an appropriate ventilation-based fire control strategy to minimize the potential fire hazards. Besides, the analysis serves to assess the general ability of FDS to simulate the specified ventilation controlled fire scenarios. The modelling features in the above code that can be employed to handle such cases are also discussed.