Safety and reliability in glovebox operations can be significantly improved and waste packaging efficiencies can be increased by inserting flexible, lightweight, high capacity HEPA filters into the walls of plastic sheet barriers. This HEPA filter/barrier technology can be adapted to a wide variety of applications: disposable waste bags, protective environmental barriers for electronic equipment, single or multiple use glovebag assemblies, flexible glovebox wall elements, and room partitions. These reliable and inexpensive filtered barriers have many uses in fields such as radioactive waste processing, HVAC filter changeout, vapor or grit blasting, asbestos cleanup, pharmaceutical, medical, biological, and electronic equipment containment. The applications can result in significant cost savings, improved operational reliability and safety, and total waste volume reduction. This technology was developed at the Argonne National Laboratory-West (ANL-W) in 1993 and has been used at ANL-W since then at the TRU Waste Characterization Chamber Gloveboxes. Another 1998 AGS Conference paper titled "TRU Waste Characterization Gloveboxes", presented by Mr. David Duncan of ANL-W, describes these boxes

Pinson, P. A.

UNT Digital Library

INEEL/CON-98-00660PREPRINTImproved HEPA Filter Technology for Flexibleand Rigid Containment BarriersPaul PinsonJuly 15, 1998 – July 17, 1998American Glovebox Society 1998 Conference571.03 - 03/23/98 - Rev. 01This is a preprint of a paper intended for publication in ajournal or proceedings. Since changes may be madebefore publication, this preprint should not be cited orreproduced without permission of the author.This document was prepared as a account of worksponsored by an agency of the United States Government.Neither the United States Government nor any agencythereof, or any of their employees, makes any warranty,expressed or implied, or assumes any legal liability orresponsibility for any third party's use, or the results ofsuch use, of any information, apparatus, product orprocess disclosed in this report, or represents that itsuse by such third party would not infringe privatelyowned rights. The views expressed in this paper arenot necessarily those of the U.S. Government or thesponsoring agency.Paul PinsonIdaho National Engineering and Environmental Laboratory (INEEL)Lockheed Martin Idaho Technologies Co. (LMITCO)Idaho Falls, ID 83415IMPROVED HEPA FILTER TECHNOLOGYFORFLEXIBLE AND RIGID CONTAINMENT BARRIERSAbstract: Safety and reliability in glovebox operations can be significantly improved andwaste packaging efficiencies can be increased by inserting flexible, lightweight, highcapacity HEPA filters into the walls of plastic sheet barriers.  This HEPA filter/barriertechnology can be adapted to a wide variety of applications: disposable waste bags,protective environmental barriers for electronic equipment, single or multiple use glovebagassemblies, flexible glovebox wall elements, and room partitions.  These reliable andinexpensive filtered barriers have many uses in fields such as radioactive waste processing,HVAC filter changeout, vapor or grit blasting, asbestos cleanup, pharmaceutical, medical,biological, and electronic equipment containment.  The applications can result in significantcost savings, improved operational reliability and safety, and total waste volume reduction.This technology was developed at the Argonne National Laboratory-West (ANL-W) in 1993and has been used at ANL-W since then at the TRU Waste Characterization ChamberGloveboxes. Another 1998 AGS Conference paper titled  "TRU Waste CharacterizationGloveboxes", presented by Mr. David Duncan of ANL-W, describes these boxes.INTRODUCTIONHigh flow capacity, flexible, and rugged High Efficiency Particulate Air (HEPA) filterssimilar to the one shown in Figure 1 are typically made from a cloth-like material called blownmicrofiber (BMF) polypropylene.FIGURE 1Center Baffle Filter ElementCircular Edge WeldScrimAdapter FittingTYPICAL CIRCULAR FLEXIBLE BREATHING AIR MASK FILTER(FILTER SECTIONED FOR CLARITY)Polypropylene is sprayed in molten form onto a flat or large cylindrical surface to create longthin mats of nonwoven fabric. These mats are layered to produce the filtering efficiency needed.This media has excellent wet strength and will not support the growth of mold, mildew, fungus,or bacteria.  The BMF fabrication process can be tailored to produce a variety of media that issuitable for specific services such as air filters, waste containment box liners, filter vented wastebags, or clean room environment barriers. Because the filter media is made in large rolls likeregular cloth, the size of the filter is easily adaptable within reasonable limits to meet the needs ofthe application.HEPA filters are practicable for many applications in industries serviced by glovebox andglovebag manufacturers. The filters are made to attach to breathing air masks by the adapterfitting. Thermal impulse heat sealing is the preferred method to join BMF HEPA filters topolyethylene plastic barrier material because it produces a permanently welded high integrityjoint that is flexible and tough with a much longer life than an adhesive joint. The thermal heatsealing joint is better than rigidly mounted filters because it can flex around corners that couldtear barrier material from rigid filters and it provides improved operational safety. Other barrier materials such as polyvinyl chloride (PVC) and polyurethane are not directlyheat sealable to BMF filters and require special adaptations to bond the filter to the barrier.  ANL-W, where this technology was developed, currently uses PVC glovebags similar to the one inFigure 2 with this type of filter installed.Argonne National Laboratories-West Bag with Filters Installed55 Gallon DrumANL-W BagRigid LinerFiltersGlovebox Bagging RingFIGURE 2Their method of mounting the filter is to create a pocket for the filter within the bag as shownin Figure 3.Othe dmadetape ther methods are being developed for sealing to PVC and polyurethane that would improveurability of the filter mounting. A similar pocketing technique identified in Figure 4 can be airtight by sealing the barrier material to the flange of the adapter fitting. Special fittings orcan cover the outlet of the adapter fitting to seal the bag.Center Baffle Filter ElementCircular Edge Weld ScrimCONTINUOUS VENTING  PVC POCKET AROUND FILTER (FILTER SECTIONED FOR CLARITY)Adapter FittingPVC BarrierMaterialAround FilterFIGURE 3AIRTIGHT SEALABLE PVC POCKET AROUND FILTER (FILTER SECTIONED FOR CLARITY)Center Baffle Filter ElementCircular Edge Weld ScrimPVC BarrierMaterialAround FilterAdapter FittingFIGURE 4Containment bags with BMF filters could increase the loading of Pu238 contaminatedradioactive waste in 55-gallon drums (thus decreasing costs associated with packaging andshipping) destined for shipment to the Waste Isolation Pilot Plant (WIPP).  Some wastepackaging is limited by the ability of the bag filters to diffuse hydrogen and keep theconcentration below the lower explosive limit. Specialized, inert, or controlled flowing gasenvironments can be established inside barriers while maintaining filtered inlets and outlets.Inserting the high flow capacity HEPA filter into an otherwise airtight barrier allows the barrier tobreathe quickly and adjust to pressure changes. The time needed to deflate a sealed containmentbag can be significantly reduced and sudden pressure changes or reversals will not cause loss ofcontainment.A parallel technology exists in polypropylene athletic garments (such as, layered inside aGortex shell) made from BMF. The resulting product is both waterproof and breathable.  Likeathletic garments, this filter technology can be expanded by tailoring the mat material or byselectively layering the mat with other media to include enhanced features that are available bylayering or bonding the BMF with special materials that adsorb, absorb, or chemically react withvapors, mists, or gasses.TECHNOLOGY BASISBMF filter material is made by spray forming a thin mat of polypropylene fibers into largesheets of filter media in a manner similar to the way paint is sprayed from a paint gun onto asurface. The thin mats are layered with as many filter mats as desired to perform the needed filterfunction. Each filter is usually covered with a BMF scrim, or cover material, to protect it fromabrasion and add enough structural integrity for the filters to be used in large sheets. The BMFfilter material can also be layered with other media or absorbent materials to filter nuisance levelsof various mists. The resulting filters are rugged, flexible, and easily sized to meet anyapplication.These filters are ideal for filter mask applications because they are relatively inexpensive,reliable, and simple to manufacture.  Safety respirator mask manufacturers including 3M, NorthSafety, and US Safety are using polypropylene blown microfibers (BMF) to produce small,flexible, rugged, and high capacity HEPA filters. The 3M and US Safety filters rely onelectrostatics to enhance filtering with charged fiber filters, while the North system relies onmechanical filtering. By using various additives, 3M tailors media to specifically filter outnuisance levels of acid gas and organic vapors.TECHNICAL CHALLENGESA problem in fabricating filter/barriers is that polypropylene filters will only heat seal topolyethylene or polypropylene sheeting. Directly bonding a polypropylene filter into apolyethylene barrier by a thermal impulse heat seal is the preferred method of barrierconstruction.  The two materials are similar enough in chemical structure that a satisfactory weldcan be achieved with appropriate equipment. This method of direct plastic welding has not beenachieved for filter attachment to PVC or polyurethane sheets. Radio frequency (RF) andultrasonic welding methods have been attempted unsuccessfully. PVC and polyurethane requireother methods that include physical attachment within a pocket to hold the filter in place andadhesively bond the filter scrim to the barrier to prevent filter bypass. This method is used in theANL-W application shown previously in Figure 4.Another option is to create a patch assembly (as shown in Figure 5) that relies on housing thefilter in a scrim material that is weldable to the barrier material.ORwasearadWawagalCoDaprecombeiwitseaThmilfiltIGINAL APPLICATIONThe first known application of this type of flexible HEPA filter for other than respirator uses developed at ANL-W.  In 1993, filters manufactured by 3M were thermal impulse heatled into polyethylene waste transfer bags that were to contain the contaminants whileioactive waste was transferred from a Plutonium glovebox into 55-gallon drums. The ANL-Wste Characterization Area (WCA) Gloveboxes are used to open 55-gallon Pu contaminatedste drums for sampling and analysis. The WCA still uses this technology to safely separate 55-lon waste drums from the bagout rings on the bottom of their glovebox.  A 1998 AGSnference paper titled “TRU Waste Characterization Chamber Gloveboxes,” presented by Mr.vid Duncan, describes the gloveboxes in this facility.The need for higher capacity HEPA filters for this purpose was identified during routineoperational testing.  The facility was being checked for all operating sequences beforemissioning it for contaminated waste.  The procedure for bagout of a 55-gallon drum wasng tested. The flow capacity of the old style filter was not sufficient to rapidly deflate the baghout operators helping the filter by pushing on the bag. The solution for this problem was torch for a higher capacity, low physical profile HEPA filter and adapt it to the containment bag.e low profile requirement was necessary because the filter had to fit between the top of the 90- rigid liner and the drum lid. This was accomplished by direct thermal heat sealing a 3M 2040er to a polyethylene waste bag. The new filter had about 100 times the flow capacity of theCIRCULAR PATCH WELDABLE FILTER (FILTER SECTIONED FOR CLARITY)Center Baffle Filter ElementCircular Edge Weld(Made at final assembly)ScrimBarrier MaterialWeldable Patch Weldable PatchAdapter FittingFIGURE 5previous filter and rapidly deflated the bag. The improved bagout system has been used forseveral hundred bagouts without any problems.APPLICATIONS IN DIVERSE FIELDSThe following applications have been identified as concepts that could benefit from thistechnology.•  Medical isolation tents could be created to isolate patients to control contagious diseases.The filtered air inlet and outlet panels would filter air with the rest of the room or the tentcould be sealed from the outside environment with specially purified and filteredatmospheres.  This could be used to provide unique care conditions for a patient withspecial susceptibilities.•  Microenvironments for biological or medical experimentation could be created withspecially filtered bags. The experimental environment could be controlled and after thetest all the contents could be left in the bag and the entire experiment could be destroyedby incineration or rendered harmless by autoclaving.•  Biological hazardous waste containment could be evacuated by attaching a vacuum to theoutlet of the filter for volume reduction and later destroyed by incineration orautoclaving.•  A sand, grit, or other particle blasting tent could be created to house the blast nozzle onapplications where the byproducts are contained for ease of cleanup or safety.•  Containment for dry ice pellet blast cleaning of contaminated parts could be created thatwould result in the CO2 evaporating and only the material removed from the partremaining inside the bag. This would be especially valuable for processes like leadcleanup where the blasting byproducts are hazardous.•  Protective packaging could be made for sensitive electronic equipment. In thisapplication, special bags could be made with filtered inlet and outlets that are located atthe same place the equipment normally draws and discharges air. This could be used forheavy construction, farming, or military equipment where the outside environment is notcontrollable.•  Pressure equalization barrier to withstand changes in pressure across the barrier could becreated. An example is a series of barriers within a large area that creates smallerchambers where smaller areas can be decontaminated individually. The smaller areasremain isolated so they do not become recontaminated as the cleaning process iscompleted.•  Gloveboxes with HEPA filtered flow-through ventilation systems could be created. Theywould normally rely on negative internal pressure to prevent contaminating the outsideareas. This method could minimize the possibility of contaminating the outsideenvironment if pressure inside the box becomes positive.VARIATIONS IN MOUNTING DESIGN CREATE DIFFERENT OPERATIONALCAPABILITIESThe filters can be mounted in the barrier in several different ways to provide the followingfeatures:•  Airtight mounting of a single filter in a bag type barrier with an integral outlet fitting sothe only exit from the filter is through the outlet, creating an airtight barrier. This barriercan then be used for deflating and sealing compressible waste.  The waste would besealed inside the bag with a linear heat seal (Seal-a-Meal type) and then the air would bevacuumed from the bag without spreading contaminants.•  Airtight mounting of two filters with outlet fittings on opposite sides of the volumeenclosing barrier to create a microenvironment in which experiments could be performedwith controlled atmospheric conditions. Both the inlet and outlet would be filtered toprevent introduction or escape of undesired products or contaminants. This is an idealconstruction for contagious disease testing on mice or other biological testing systems.•  Open face mounting of small filters without fittings provide continuous venting of gassesgenerated inside the barrier. This is ideal for packaging that needs to vent radiolyticlygenerated hydrogen to prevent the buildup of explosive levels of gasses.•  Large panel mounted filters in walls or ceilings provide excellent protection fromoverpressure conditions. The sudden starting or stopping of a large air-circulating fanwould not collapse a barrier that was made of this type of material. Such a barrier couldzone a large contaminated area into smaller easier cleaned zones for individualreclamation.•  Panel or frame mounted filters could provide low flow resistance and pre-filters forHEPA or other filters that are subjected to high loading from dust or other contaminants.The pre-filters would reduce the complexity of changeout of the HEPA filter and if thedesign of the containment was amenable, the pre-filter could be collapsed and bagged outfrom inside of the containment with much greater ease than the main filter.•  Custom bags with special inlet and outlet HEPA filters could protect temperature or dustsensitive electronics or other items that require clean cooling air to be blown across theequipment. The bag filtered inlets and outlets would be strategically placed to direct theairflow across the normal equipment cooling paths.HOW THIS TECHNOLOGY CAN BENEFIT INDUSTRYThis technology is being evaluated for use in packaging waste to ship to WIPP.  Someradioactive waste forms are shipped to WIPP in sealed 55-gallon drums that have been fitted withHEPA drum vent filters in the lids to vent H2 that might have been generated by radiolyticdecomposition of hydrogenous materials.The amount of radioactive waste that can be shipped in each drum is severely limited unlessthe plastic barriers inside the drums are also vented. H2 diffusivity of the drum and bag ventfilters must be adequate to prevent the buildup of the H2 inside the drum from reaching anexplosive level. The HEPA filters installed in plastic bags with this technology have a highenough diffusivity that they can eliminate the waste loading restrictions that are imposed becauseof H2 buildup. It is feasible that a 20% increase in waste loading could be achieved. This wouldresult in significant cost savings in shipping and storing WIPP waste.SUMMARYFiltering is not the only advantage BMF filter materials can provide to the glovebox andglovebag industries. Uncontrollable pressure differentials across flexible or rigid barriers can bemitigated if a large segment of the barrier is made from this material.  Temporary plastic wallscould be made to withstand sudden pressure transients that could occur when HVAC equipmentstarts or stops and specialized plastic covers could be created for electronic equipment that isexposed to contaminating environments. The bag could allow filtered air to enter and exit thecover thereby cooling the equipment and protecting it from dust and other contaminants.Developments in this field can enhance safety, significantly reduce costs, and simplify operations.Temporary and semi-permanent installations of gloveboxes and glovebags can be made faster,better and cheaper.  Developing cheap, readily available, and disposable containment barrierscould reduce the occurrence of cross contamination or recontamination of clean equipment.ACKNOWLEDGEMENTSThis work was originally developed under federally funded research and developmentconducted at the Idaho National Engineering and Environmental Laboratory under U.S.Department of Energy Contract.The original application of this technology was conceived and developed by Paul A. Pinson,who was granted US Patent No. 5.720,789 on February 24, 1998 titled “METHOD FORCONTAMINATION CONTROL AND BARRIER APPARATUS WITH FILTER FORCONTAINING WASTE MATERIALS THAT INCLUDE DANGEROUS PARTICULATEMATTER.”  The rights for this patent were assigned to Lockheed Martin Idaho TechnologiesCompany, Idaho Falls, ID.

Improved HEPA Filter Technology for Flexible and Rigid Containment Barriers

Pinson, Paul Arthur

INEEL/CON-98-00660PREPRINTImproved HEPA Filter Technology for Flexibleand Rigid Containment BarriersPaul PinsonJuly 15, 1998 – July 17, 1998American Glovebox Society 1998 Conference571.03 - 03/23/98 - Rev. 01This is a preprint of a paper intended for publication in ajournal or proceedings. Since changes may be madebefore publication, this preprint should not be cited orreproduced without permission of the author.This document was prepared as a account of worksponsored by an agency of the United States Government.Neither the United States Government nor any agencythereof, or any of their employees, makes any warranty,expressed or implied, or assumes any legal liability orresponsibility for any third party's use, or the results ofsuch use, of any information, apparatus, product orprocess disclosed in this report, or represents that itsuse by such third party would not infringe privatelyowned rights. The views expressed in this paper arenot necessarily those of the U.S. Government or thesponsoring agency.Paul PinsonIdaho National Engineering and Environmental Laboratory (INEEL)Lockheed Martin Idaho Technologies Co. (LMITCO)Idaho Falls, ID 83415IMPROVED HEPA FILTER TECHNOLOGYFORFLEXIBLE AND RIGID CONTAINMENT BARRIERSAbstract: Safety and reliability in glovebox operations can be significantly improved andwaste packaging efficiencies can be increased by inserting flexible, lightweight, highcapacity HEPA filters into the walls of plastic sheet barriers.  This HEPA filter/barriertechnology can be adapted to a wide variety of applications: disposable waste bags,protective environmental barriers for electronic equipment, single or multiple use glovebagassemblies, flexible glovebox wall elements, and room partitions.  These reliable andinexpensive filtered barriers have many uses in fields such as radioactive waste processing,HVAC filter changeout, vapor or grit blasting, asbestos cleanup, pharmaceutical, medical,biological, and electronic equipment containment.  The applications can result in significantcost savings, improved operational reliability and safety, and total waste volume reduction.This technology was developed at the Argonne National Laboratory-West (ANL-W) in 1993and has been used at ANL-W since then at the TRU Waste Characterization ChamberGloveboxes. Another 1998 AGS Conference paper titled  "TRU Waste CharacterizationGloveboxes", presented by Mr. David Duncan of ANL-W, describes these boxes.INTRODUCTIONHigh flow capacity, flexible, and rugged High Efficiency Particulate Air (HEPA) filterssimilar to the one shown in Figure 1 are typically made from a cloth-like material called blownmicrofiber (BMF) polypropylene.FIGURE 1Center Baffle Filter ElementCircular Edge WeldScrimAdapter FittingTYPICAL CIRCULAR FLEXIBLE BREATHING AIR MASK FILTER(FILTER SECTIONED FOR CLARITY)Polypropylene is sprayed in molten form onto a flat or large cylindrical surface to create longthin mats of nonwoven fabric. These mats are layered to produce the filtering efficiency needed.This media has excellent wet strength and will not support the growth of mold, mildew, fungus,or bacteria.  The BMF fabrication process can be tailored to produce a variety of media that issuitable for specific services such as air filters, waste containment box liners, filter vented wastebags, or clean room environment barriers. Because the filter media is made in large rolls likeregular cloth, the size of the filter is easily adaptable within reasonable limits to meet the needs ofthe application.HEPA filters are practicable for many applications in industries serviced by glovebox andglovebag manufacturers. The filters are made to attach to breathing air masks by the adapterfitting. Thermal impulse heat sealing is the preferred method to join BMF HEPA filters topolyethylene plastic barrier material because it produces a permanently welded high integrityjoint that is flexible and tough with a much longer life than an adhesive joint. The thermal heatsealing joint is better than rigidly mounted filters because it can flex around corners that couldtear barrier material from rigid filters and it provides improved operational safety. Other barrier materials such as polyvinyl chloride (PVC) and polyurethane are not directlyheat sealable to BMF filters and require special adaptations to bond the filter to the barrier.  ANL-W, where this technology was developed, currently uses PVC glovebags similar to the one inFigure 2 with this type of filter installed.Argonne National Laboratories-West Bag with Filters Installed55 Gallon DrumANL-W BagRigid LinerFiltersGlovebox Bagging RingFIGURE 2Their method of mounting the filter is to create a pocket for the filter within the bag as shownin Figure 3.Other methods are being developed for sealing to PVC and polyurethane that would improvethe durability of the filter mounting. A similar pocketing technique identified in Figure 4 can bemade airtight by sealing the barrier material to the flange of the adapter fitting. Special fittings ortape can cover the outlet of the adapter fitting to seal the bag.Center Baffle Filter ElementCircular Edge Weld ScrimCONTINUOUS VENTING  PVC POCKET AROUND FILTER(FILTER SECTIONED FOR CLARITY)Adapter FittingPVC BarrierMaterialAround FilterFIGURE 3AIRTIGHT SEALABLE PVC POCKET AROUND FILTER(FILTER SECTIONED FOR CLARITY)Center Baffle Filter ElementCircular Edge Weld ScrimPVC BarrierMaterialAround FilterAdapter FittingFIGURE 4Containment bags with BMF filters could increase the loading of Pu238 contaminatedradioactive waste in 55-gallon drums (thus decreasing costs associated with packaging andshipping) destined for shipment to the Waste Isolation Pilot Plant (WIPP).  Some wastepackaging is limited by the ability of the bag filters to diffuse hydrogen and keep theconcentration below the lower explosive limit. Specialized, inert, or controlled flowing gasenvironments can be established inside barriers while maintaining filtered inlets and outlets.Inserting the high flow capacity HEPA filter into an otherwise airtight barrier allows the barrier tobreathe quickly and adjust to pressure changes. The time needed to deflate a sealed containmentbag can be significantly reduced and sudden pressure changes or reversals will not cause loss ofcontainment.A parallel technology exists in polypropylene athletic garments (such as, layered inside aGortex shell) made from BMF. The resulting product is both waterproof and breathable.  Likeathletic garments, this filter technology can be expanded by tailoring the mat material or byselectively layering the mat with other media to include enhanced features that are available bylayering or bonding the BMF with special materials that adsorb, absorb, or chemically react withvapors, mists, or gasses.TECHNOLOGY BASISBMF filter material is made by spray forming a thin mat of polypropylene fibers into largesheets of filter media in a manner similar to the way paint is sprayed from a paint gun onto asurface. The thin mats are layered with as many filter mats as desired to perform the needed filterfunction. Each filter is usually covered with a BMF scrim, or cover material, to protect it fromabrasion and add enough structural integrity for the filters to be used in large sheets. The BMFfilter material can also be layered with other media or absorbent materials to filter nuisance levelsof various mists. The resulting filters are rugged, flexible, and easily sized to meet anyapplication.These filters are ideal for filter mask applications because they are relatively inexpensive,reliable, and simple to manufacture.  Safety respirator mask manufacturers including 3M, NorthSafety, and US Safety are using polypropylene blown microfibers (BMF) to produce small,flexible, rugged, and high capacity HEPA filters. The 3M and US Safety filters rely onelectrostatics to enhance filtering with charged fiber filters, while the North system relies onmechanical filtering. By using various additives, 3M tailors media to specifically filter outnuisance levels of acid gas and organic vapors.TECHNICAL CHALLENGESA problem in fabricating filter/barriers is that polypropylene filters will only heat seal topolyethylene or polypropylene sheeting. Directly bonding a polypropylene filter into apolyethylene barrier by a thermal impulse heat seal is the preferred method of barrierconstruction.  The two materials are similar enough in chemical structure that a satisfactory weldcan be achieved with appropriate equipment. This method of direct plastic welding has not beenachieved for filter attachment to PVC or polyurethane sheets. Radio frequency (RF) andultrasonic welding methods have been attempted unsuccessfully. PVC and polyurethane requireother methods that include physical attachment within a pocket to hold the filter in place andadhesively bond the filter scrim to the barrier to prevent filter bypass. This method is used in theANL-W application shown previously in Figure 4.Another option is to create a patch assembly (as shown in Figure 5) that relies on housing thefilter in a scrim material that is weldable to the barrier material.ORIGINAL APPLICATIONThe first known application of this type of flexible HEPA filter for other than respirator usewas developed at ANL-W.  In 1993, filters manufactured by 3M were thermal impulse heatsealed into polyethylene waste transfer bags that were to contain the contaminants whileradioactive waste was transferred from a Plutonium glovebox into 55-gallon drums. The ANL-WWaste Characterization Area (WCA) Gloveboxes are used to open 55-gallon Pu contaminatedwaste drums for sampling and analysis. The WCA still uses this technology to safely separate 55-gallon waste drums from the bagout rings on the bottom of their glovebox.  A 1998 AGSConference paper titled “TRU Waste Characterization Chamber Gloveboxes,” presented by Mr.David Duncan, describes the gloveboxes in this facility.The need for higher capacity HEPA filters for this purpose was identified during routinepreoperational testing.  The facility was being checked for all operating sequences beforecommissioning it for contaminated waste.  The procedure for bagout of a 55-gallon drum wasbeing tested. The flow capacity of the old style filter was not sufficient to rapidly deflate the bagwithout operators helping the filter by pushing on the bag. The solution for this problem was tosearch for a higher capacity, low physical profile HEPA filter and adapt it to the containment bag.The low profile requirement was necessary because the filter had to fit between the top of the 90-mil rigid liner and the drum lid. This was accomplished by direct thermal heat sealing a 3M 2040filter to a polyethylene waste bag. The new filter had about 100 times the flow capacity of theCIRCULAR PATCH WELDABLE FILTER(FILTER SECTIONED FOR CLARITY)Center Baffle Filter ElementCircular Edge Weld(Made at final assembly)ScrimBarrier MaterialWeldable Patch Weldable PatchAdapter FittingFIGURE 5previous filter and rapidly deflated the bag. The improved bagout system has been used forseveral hundred bagouts without any problems.APPLICATIONS IN DIVERSE FIELDSThe following applications have been identified as concepts that could benefit from thistechnology.• Medical isolation tents could be created to isolate patients to control contagious diseases.The filtered air inlet and outlet panels would filter air with the rest of the room or the tentcould be sealed from the outside environment with specially purified and filteredatmospheres.  This could be used to provide unique care conditions for a patient withspecial susceptibilities.• Microenvironments for biological or medical experimentation could be created withspecially filtered bags. The experimental environment could be controlled and after thetest all the contents could be left in the bag and the entire experiment could be destroyedby incineration or rendered harmless by autoclaving.• Biological hazardous waste containment could be evacuated by attaching a vacuum to theoutlet of the filter for volume reduction and later destroyed by incineration orautoclaving.• A sand, grit, or other particle blasting tent could be created to house the blast nozzle onapplications where the byproducts are contained for ease of cleanup or safety.• Containment for dry ice pellet blast cleaning of contaminated parts could be created thatwould result in the CO2 evaporating and only the material removed from the partremaining inside the bag. This would be especially valuable for processes like leadcleanup where the blasting byproducts are hazardous.• Protective packaging could be made for sensitive electronic equipment. In thisapplication, special bags could be made with filtered inlet and outlets that are located atthe same place the equipment normally draws and discharges air. This could be used forheavy construction, farming, or military equipment where the outside environment is notcontrollable.• Pressure equalization barrier to withstand changes in pressure across the barrier could becreated. An example is a series of barriers within a large area that creates smallerchambers where smaller areas can be decontaminated individually. The smaller areasremain isolated so they do not become recontaminated as the cleaning process iscompleted.• Gloveboxes with HEPA filtered flow-through ventilation systems could be created. Theywould normally rely on negative internal pressure to prevent contaminating the outsideareas. This method could minimize the possibility of contaminating the outsideenvironment if pressure inside the box becomes positive.VARIATIONS IN MOUNTING DESIGN CREATE DIFFERENT OPERATIONALCAPABILITIESThe filters can be mounted in the barrier in several different ways to provide the followingfeatures:• Airtight mounting of a single filter in a bag type barrier with an integral outlet fitting sothe only exit from the filter is through the outlet, creating an airtight barrier. This barriercan then be used for deflating and sealing compressible waste.  The waste would besealed inside the bag with a linear heat seal (Seal-a-Meal type) and then the air would bevacuumed from the bag without spreading contaminants.• Airtight mounting of two filters with outlet fittings on opposite sides of the volumeenclosing barrier to create a microenvironment in which experiments could be performedwith controlled atmospheric conditions. Both the inlet and outlet would be filtered toprevent introduction or escape of undesired products or contaminants. This is an idealconstruction for contagious disease testing on mice or other biological testing systems.• Open face mounting of small filters without fittings provide continuous venting of gassesgenerated inside the barrier. This is ideal for packaging that needs to vent radiolyticlygenerated hydrogen to prevent the buildup of explosive levels of gasses.• Large panel mounted filters in walls or ceilings provide excellent protection fromoverpressure conditions. The sudden starting or stopping of a large air-circulating fanwould not collapse a barrier that was made of this type of material. Such a barrier couldzone a large contaminated area into smaller easier cleaned zones for individualreclamation.• Panel or frame mounted filters could provide low flow resistance and pre-filters forHEPA or other filters that are subjected to high loading from dust or other contaminants.The pre-filters would reduce the complexity of changeout of the HEPA filter and if thedesign of the containment was amenable, the pre-filter could be collapsed and bagged outfrom inside of the containment with much greater ease than the main filter.• Custom bags with special inlet and outlet HEPA filters could protect temperature or dustsensitive electronics or other items that require clean cooling air to be blown across theequipment. The bag filtered inlets and outlets would be strategically placed to direct theairflow across the normal equipment cooling paths.HOW THIS TECHNOLOGY CAN BENEFIT INDUSTRYThis technology is being evaluated for use in packaging waste to ship to WIPP.  Someradioactive waste forms are shipped to WIPP in sealed 55-gallon drums that have been fitted withHEPA drum vent filters in the lids to vent H2 that might have been generated by radiolyticdecomposition of hydrogenous materials.The amount of radioactive waste that can be shipped in each drum is severely limited unlessthe plastic barriers inside the drums are also vented. H2 diffusivity of the drum and bag ventfilters must be adequate to prevent the buildup of the H2 inside the drum from reaching anexplosive level. The HEPA filters installed in plastic bags with this technology have a highenough diffusivity that they can eliminate the waste loading restrictions that are imposed becauseof H2 buildup. It is feasible that a 20% increase in waste loading could be achieved. This wouldresult in significant cost savings in shipping and storing WIPP waste.SUMMARYFiltering is not the only advantage BMF filter materials can provide to the glovebox andglovebag industries. Uncontrollable pressure differentials across flexible or rigid barriers can bemitigated if a large segment of the barrier is made from this material.  Temporary plastic wallscould be made to withstand sudden pressure transients that could occur when HVAC equipmentstarts or stops and specialized plastic covers could be created for electronic equipment that isexposed to contaminating environments. The bag could allow filtered air to enter and exit thecover thereby cooling the equipment and protecting it from dust and other contaminants.Developments in this field can enhance safety, significantly reduce costs, and simplify operations.Temporary and semi-permanent installations of gloveboxes and glovebags can be made faster,better and cheaper.  Developing cheap, readily available, and disposable containment barrierscould reduce the occurrence of cross contamination or recontamination of clean equipment.ACKNOWLEDGEMENTSThis work was originally developed under federally funded research and developmentconducted at the Idaho National Engineering and Environmental Laboratory under U.S.Department of Energy Contract.The original application of this technology was conceived and developed by Paul A. Pinson,who was granted US Patent No. 5.720,789 on February 24, 1998 titled “METHOD FORCONTAMINATION CONTROL AND BARRIER APPARATUS WITH FILTER FORCONTAINING WASTE MATERIALS THAT INCLUDE DANGEROUS PARTICULATEMATTER.”  The rights for this patent were assigned to Lockheed Martin Idaho TechnologiesCompany, Idaho Falls, ID.

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Improved HEPA Filter Technology for Flexible and Rigid Containment Barriers

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