Phase I aging assessment of nuclear air-treatment system high efficiency particulate air and adsorbers

A phase I aging assessment of high efficiency particulate air filters and activated carbon gas adsorption units was performed by the Pacific Northwest Laboratory as part of the US Nuclear Regulatory Commission's Nuclear Plant Aging Research Program. Information was compiled concerning design features, failure experience, aging mechanisms, effects, and stressors, and monitoring methods. Over 1100 failures, or 12% of the filter installations, were reported as part of a US Department of energy survey. Investigators from other laboratories have suggested that aging could have contributed to over 80% of these failures. Several instances of impaired performance as the result of the premature aging of carbon were reported. Filter aging mechanisms range from those associated with particle loading to reactions that alter the properties of gaskets. Mechanisms that can lead to impaired adsorber performance include the loss of potentially available active sites as a result of the adsorption of moisture or pollutants. Stressors include heat, moisture, radiation, and airborne particles and contaminants. (orig.)