Technical Area 3 - 40; Physics Building- Fire and Life Safety Analysis

A Fire Protection Engineering Analysis was performed on TA‐3‐0040, Physics Building at the Los Alamos National Laboratory in Los Alamos, New Mexico. The goal of the analysis has two parts; first, to examine the buildings fire protection features from a code based prescriptive analysis and second, to examine the building and fire protection features using a performance based design analysis. Building 40 is a 2 story structure approximately 187,000 square feet. The building was constructed in the mid‐1950s with a first floor, basement, partial sub‐basement, and various mezzanines. Originally, this building was constructed as a non‐combustible type IIB structure according to IBC 2012 edition. Current fire barriers and fire doors throughout the facility are no longer credible due to unsealed penetrations and lack of inspection, testing and maintenance (ITM). A sprinkler system was installed in the mid‐1970s; various changes have been made to the system since installation. Current analysis shows there is adequate supply for the sprinkler system. The fire alarm system was upgraded to an NFPA 72 compliant, fully addressable system in 2014. An egress analysis on Building 40 showed that the building has adequate exit capacity and adequate exit separation. Computer software such as Pathfinder ®, Pyrosim®, and Fire Dynamic Simulator (FDS) were used to aid in the analysis of the performance based design section. In order to examine if occupants have acceptable conditions to be able to evacuate the building, tenability criteria were determined and examined for two different fire scenarios. These conditions were used to determine the Available Safe Egress Time (ASET) for occupants and compared against the Required Safe Egress Time (RSET) based on the design fire scenarios. In the first fire scenario a fire starts in a machine shop under a mezzanine, which only has one exit. During modeling simulations, it was found that after 179 seconds (ASET) occupants would have to travel through a layer of smoke and hot gas to get down from the mezzanine. Because this portion of the building does not have detection, the RSET was calculated to be 347 seconds. Therefore, the life safety criteria for this scenario was not met. In the second scenario a fire starts in a server room due to electrical failure and spreads to stored combustibles which leads to full room involvement. The door to this room is open and smoke is allowed to fill the corridor. In this scenario smoke fills the corridor to the point where visibility is obstructed. Occupant visibility is significantly obscured after 204 seconds (ASET) and 250 seconds are needed for all occupants to exit the building. Therefore, the life safety criteria for this scenario is also not met