Three gaseous effluent monitor systems collect air within the National Bureau of Standards Reactor (NBSR) confinement building. The normal air channel measures air sampled from the normal air, process room air, and emergency ventilation systems. The irradiated air channel measures air sampled from the irradiated air, confinement hoods, and emergency recirculating systems. All the collected air is combined and re-measured by the stack channels. Each of these channels provides radiation alarms and protective safety actions. Furthermore, these systems provide redundant protection against personnel exposure and uncontrolled release of radioactive material to the environment. The normal air channel continuously monitors the exhaust air leaving the building for gaseous radioactive release. A vacuum pump draws air, from a sample tap in the normal air duct downstream of the HEPA filters, through a shielded detector chamber. The existing analog system utilizes a Geiger-Mueller probe sensitive to the beta-gamma radiation emitted by the gaseous airborne radioactivity (predominately AR-41). A pre-amplifier connects the detector to the counting circuits in the log-count ratemeter. The ratemeter has alarm outputs that actuate the major scram circuits and the annunciator system. The building exhaust activity high alarm alerts the reactor operator to a high activity condition in the normal air monitoring system. The new system selected to replace the normal air channel is comprised of a digital ratemeter and scintillation detector which, based on the company provided documentation, has been through a rigorous analysis for use in safety-related nuclear systems. As utilized at the NBSR, the unit does not have digital communication and is used for its intended purpose without modification to the ratemeter. The digital unit does not change how the design function of the normal air channel is performed, i.e. the new unit measures radioactive isotope concentrations in the gas samples using a radiation detector. The new radiation detector is similar with regards to radiation detection capabilities and has a greater dose rate range capability compared to the existing detector. A detailed assessment of existing and the new detector capabilities was conducted to identify differences. The most significant deviation was that the new normal air monitoring channel introduces a digital logic for the quantification of radiation levels. The use of digital equipment (hardware and software) therefore has the potential of creating a new type of malfunction that was not previously considered and needed to be analyzed to determine the impact on the pertinent design functions as a safety system.