Auxiliary Ventilation Systems Design Basis and Analysis Approach

Auxiliary systems supporting pressurized water reactors (PWR) within commercial nuclear power plants are enclosed within a special ventilation (SV) zone that is isolated post-accident. Air within the SV zone is recirculated through carbon adsorbers, and discharged at a rate equal to the SV zone air infiltration rate. The SV zone relies on safety-related fan coil units (FCUs) to remove heat since air infiltration is kept to a minimum in order to reduce the spread of contamination. This paper discusses efforts undertaken to quantify area heat loads and FCU operating conditions within the SV zone, and transient analyses performed for loss of FCUs using the GOTHIC code.