Near real time predictions of fire and smoke spread with complex ventilation

Ships, large buildings, and nuclear power plants are all large multiple compartment structures that have complex ventilation systems. Predicting the long term spread of fire and smoke in such facilities with active ventilation is a difficult task. Traditional multi-compartment fire models like CFAST, while fast, cannot handle complex ventilation. Indoor air quality models such as CONTAM can model complex ventilation but lack the physics needed Picture_Section 1 - Services_Risk and Hazards Analysis_Modeling_FSSIMfor fire spread. CFD models, while capable of handling complex ventilation and predicting fire spread, are resource expensive. JENSEN HUGHES recognized this gap in fire modeling and developed FSSIM (Fire and Smoke Simulator). FSSIM is a network fire model capable of predicting fire and smoke spread in large structures with ventilation. Originally developed to predict fire and smoke spread in naval vessels, it has also been applied to nuclear power plants and other commercial structures. FSSIM can rapidly model thousands of compartments allowing it to support probabilistic assessments that are critical to nuclear power risk assessment and determining the vulnerability of naval vessels. FSSIM is the only fire model currently accredited for use by the US Navy.


Operator Actions

Picture_Section 2 - Services_Risk and Hazards Analysis_Modeling_FSSIMNuclear power plants are regulated on the basis of reducing the core damage frequency (CDF, the odds per year that an accident will result in fuel damage). An important contributor to the CDF is fire which can damage control systems and result in smoke spread. Under some accident scenarios, primary control systems can be damaged but human action (turning a valve whose control system was damaged) can still prevent core damage. The ability to model smoke spread via ventilation systems can provide power plants a method to determine when human actions would or would not be possible. The rapid speed of FSSIM means it can be used in a probabilistic assessment.


Vulnerability and Recoverability Assessments

Naval vessels have unique fire modeling challenges. Water tight construction means complex ventilation systems, which create a path for smoke spread, are needed to maintain Picture_Section 3 - Services_Risk and Hazards Analysis_Modeling_FSSIMhabitability within the ship. Steel and aluminum construction result in rapid fire spread across compartment boundaries. Combining these with the wide range of damage that might result from combat and assessing the overall performance of a ship becomes a complicated endeavor. FSSIM has been successfully applied to predicting fire and smoke spread for aircraft carriers, troop transports, destroyers, cruisers, and other naval vessels.

Contact Us Today:

Contact us today using our online form or by contacting one of our many regional branches. For specific questions regarding JENSEN HUGHES’ FSSIM Modeling services, please contact:

For project inquiries: For technical questions:
Joe Scheffey Jason Floyd, PhD
410-737-8677 x220 410-737-8677 x236