A preliminary study on shelf life of high efficiency particulate air (HEPA) filter used in nuclear facilities

High Efficiency Particulate Air (HEPA) filters are playing major role in ventilation system of nuclear facilities. These filters are used to maintain containment of radioactive substances and provide the final barrier before discharge to the external environment both under normal operating and accident conditions. These filters are procured from the manufacturers and tested for its efficiency in the test rig facility commissioned as per British Standard BS2831. The integrity of the filter media are being tested by injecting known concentration of aerosol in the upstream and measuring the concentration level in the downstream. The measurements were carried out for pressure drop at nominal volume flow rate of 1000 CFM, with minimum collection efficiency of 99.97% for the particle size of 0.3 micron with the highest penetration (MPPS = Most Penetrating Particle Size) at nominal volume flow. This paper focus on the methodology of testing of HEPA filters to ascertain the shelf life of HEPA filters