Innovative HEPA [high-efficiency particulate air] filter designs to reduce waste generation and simplify waste treatment

The treatment and disposal of spent high-efficiency particulate air (HEPA) filters has presented a problem at some defense production plants and could be a problem at potential future spent-fuel consolidation or fuel reprocessing facilities. During studies of transuranic (TRU) waste treatment options conducted by Pacific Northwest Laboratory, it was concluded that treatment of spent HEPA filters would become easier and less costly if some modifications were made to the present materials of construction and design. This study was undertaken to develop and evaluate alternative materials and innovative designs for HEPA filters, making them more compatible with volume reduction technology. The following treatment options were selected for this study: (1) no treatment; (2) compaction; (3) supercompaction; (4) incinerate and melt; and (5) separate the frame from the media and dispose of the frame as low-level waste, and incinerate and melt the filter media and sealant. Forty HEPA design concepts were identified and evaluated by means of a figure-of-merit methodology for technical performance and an economic evaluation that considered filter fabrication and disposal costs. Results of the study indicate that if improved HEPA designs are combined with volume reduction treatments, the costs of filter disposal can be reduced substantially over the use of standard-flow filter designs with no volume reduction treatment. It is estimated that by combining the new design concepts with waste volume reduction treatments, manufacturing and disposal costs can be reduced by $290 or more per filter if classified as low-level waste (LLW) and up to $23,000 per filter if it is high-activity waste (containing activity greater than class-C LLW) and requires repository disposal