NMT-8 is proposing to upgrade the existing Facility Control System (FCS) located within the Facility Operations Center (FOC) at the TA-55 Plutonium Processing and Handling Facility (PPHF). The FCS modifications will upgrade the existing electronics to provide better reliability of system functions. Changes include replacement of the FCS computers and field multiplex units which are used for transmitting systems data. Data collected at the FCS include temperature, pressure, contact closures, etc., and are used for monitoring and/or control of key systems at TA-55. Monitoring is provided for the electrical power system status, PF-4 HVAC air balance status (Static Differential pressure), HVAC fan system status, site chill water return temperature, fire system information, and radioactive constant air monitors alarm information, site compressed air pressure and other key systems used at TA-55. Control output signals are provided for PF-4 HVAC systems, and selected alarms for criticality, fire, loss of pressure in confinement systems. A detailed description of the FCS modifications is provided in Section 2.