Abstract:
A headspace gas sampling and venting method utilizes a vent port and a sampling port which are punched through the lid of a drum containing hazardous materials, such as transuranic waste. In accordance with the system, a punch having a hollow passage therethrough, which passage has a filter element therein is first inserted through the lid using a pneumatic gun. A second punch, similar to the first punch, but having a passage with a septa seal therein is thereafter inserted through the lid with the pneumatic gun. Headspace gas beneath the lid is then sampled with a needle inserted through the septa seal. Both the venting port and sampling port are configured with detachable punch points which pass through the lid and are then released from the venting and sampling ports so as to open ends of the passages therethrough for communication with the headspace. In a preferred embodiment of the invention, the punch points are held on the venting and sampling ports by annular plastic retainers which break when the ports are inserted through the drum lid, thus allowing detachable punch points to fall away.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention is directed to a headspace gas sampling method and arrangements and filtering and sampling ports used therewith. More particularly, the present invention is directed to such method, arrangements and ports which are particularly suitable for sampling and filtering gases from waste material stored in containers, such as drums, wherein the material is a hazardous waste such as, but not limited to, transuranic waste.  
         BACKGROUND OF THE INVENTION  
         [0002]    Since 1970, transuranic waste material generated in the United States by the Department of Energy Operations has been packaged in unvented, 55-gallon steel drums, which drums have been stored with the intention of future retrieval. It is intended that the material in these drums will be disposed of permanently in the Department of Energy Waste Isolation Pilot Plant (WIIP) Facility. Currently, there are safety concerns regarding these stored drums because of the potential presence of combustible headspace gases. These gases can include hydrogen and methane, resulting from the radiolytic decomposition of hydrogenous waste materials, e.g. paper, plastics and moist materials and/or from the presence of small amounts of combustible volatile organic compounds (VOCs) that are co-contaminants of transuranic waste. Future transportation and storage of these wastes stored in drums such as 55-gallon drums must address what is to be done about these gases.  
           [0003]    The WIPP facility has waste acceptance criteria that requires that all packages stored must be vented. Moreover, those packages which are to be shipped to the Waste Isolation Pilot Plant must be vented and demonstrated to meet combustible gas concentration limits before shipping.  
           [0004]    In addition, it is necessary that these drums retain their integrity during shipment in case the drums are accidentally dropped or are involved in a road or railway accident during shipment. Since there are millions of these drums, it is assumed that there will be accidents or occurrences that may stress the drums and increase the risk of spills or leaks. It is therefore important that any sampling ports or filter ports not be dislodged so as compromise the integrity of the drums.  
           [0005]    Moreover, since the drums must be sampled and filtered, it is desirable that the sampling and application of filters be performed in an expeditious and safe manner.  
         SUMMARY OF THE INVENTION  
         [0006]    In view of the aforementioned considerations, the present invention is directed to a drum sampling and filtering arrangement wherein a sampling punch and a filtering punch are used for each drum, the sampling and filtering punches being inserted by remote control using a remotely activated drive.  
           [0007]    In a more specific aspect, the remotely activated drive is a pneumatic gun which drives the filtering punch and then the sampling punch through the lid of the drum at spaced locations through the lid.  
           [0008]    In a further aspect of the invention, a punch is configured for penetrating a wall to access a space behind the wall, wherein each punch comprises an annular body having first and second ends for passage therethrough, the passage having a first opening and a second opening. The punch point is coupled detachably the first end of annular body. The coupling releases the punch point upon inserting the punch point through the wall, whereby the first opening of the passage communicates with the space behind the wall. In accordance with a preferred arrangement, the coupling comprises a deformable element which releases the punch point upon the punch point being forced through the wall. In a more specific aspect of the invention, the coupling comprises a stud on the punch point which is received in the open end of the passage, the punch point being held in the passage by an element which releases the punch point after the punch point has penetrated the wall. In a still more particular aspect of the invention, the element which holds the stud of the punch point in the passage is a collar which disengages from the punch point as the punch point passes through the wall.  
           [0009]    In accordance with one embodiment of the punch, the passage includes the septa seal therein adapted to permit the passage of a hollow needle therethrough to sample in the space behind the wall. In accordance with another embodiment of the punch, the passage has a filter element associated therewith, wherein any fluid which passes from the first opening in the body and through the second opening in the body must pass through the filter element. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    Various other features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein:  
         [0011]    [0011]FIG. 1 is a side perspective view of a container having a lid with a sample port and a filter port disposed therein;  
         [0012]    [0012]FIG. 2 is a perspective view of a pneumatic gun used to install the sample and filter ports of FIG. 1;  
         [0013]    [0013]FIG. 3 is a top perspective view of a filter port in accordance with the present invention;  
         [0014]    [0014]FIG. 4 is a side perspective view of a filter port configured in accordance in the present invention prior to installation thereof;  
         [0015]    [0015]FIG. 5 is a side view of the filter port of FIGS. 3 and 4 installed through a wall of the container as shown in FIGS. 1 and 2;  
         [0016]    [0016]FIG. 6 is an enlarged side elevation of the filter port of FIG. 5;  
         [0017]    [0017]FIG. 7 is a top view of the filter port of FIG. 6;  
         [0018]    [0018]FIG. 8 is a top perspective view of a sampling port configured in accordance with the present invention;  
         [0019]    [0019]FIG. 9 is a side perspective view of the sampling port of FIG. 8;  
         [0020]    [0020]FIG. 10 is a side view of the sample port of FIG. 9 installed through a wall of the container of FIGS. 1 and 8;  
         [0021]    [0021]FIG. 11 is a side elevation of the sample port of FIGS.  8 - 10 ;  
         [0022]    [0022]FIG. 12 is a top view of the sample port of FIGS.  8 - 11 , and  
         [0023]    [0023]FIG. 13 is a side view similar to FIG. 10 but showing a needle withdrawing head space gas. 
     
    
     DETAILED DESCRIPTION  
       [0024]    Referring now to FIG. 1, there is shown an arrangement in accordance with the present invention wherein a container, such as a 55-gallon steel drum  10 , having a circular lid  12  formed about an axis  13  retained thereon by circular clamp  14 , is used to store waste such as transuranic waste  16 . Between the transuranic waste  16  and the lid  12  there is a headspace  18  in which headspace gases and vapors may accumulate. Since there are gases or vapors accumulating in the headspace  18 , it is necessary to vent these gases, because the gases may be explosive or flammable if allowed to accumulate in the headspace  18 . These gases present environmental hazards which could conceivably rupture the container comprised of the drum  10  on which the lid  12  is held by circular clamp  14 .  
         [0025]    In accordance with the principles of the present invention, venting is accomplished by a filter port  20  disposed through the lid  12 . It is also necessary to determine the composition of head gases accumulated in the headspace  18 . In accordance with the present invention, this is accomplished by a sampling port  22 , also inserted in the lid  12 . In accordance with the present invention, the filter port  20  and sampling port  22  in combination with the drum  10  provide a method and arrangement for handling transuranic waste  16  having gases which may present an environmental hazard and which must be known, filtered and vented in order to minimize environmental risks.  
         [0026]    While transuranic waste is a primary concern with respect to the present invention, the arrangement shown in FIG. 1 is also usable for the storage and transport of other hazardous waste or other hazardous materials, whether the materials are waste material or material to be used for some purpose.  
         [0027]    Referring now to FIG. 2, there is shown an arrangement for inserting the filtering and sampling ports  20  and  22  of FIG. 1 wherein drum  10  of FIG. 1 has temporarily mounted thereon a pneumatic gun  30  which drives the ports  20  and  22  configured as punches through the lid  12  of the drum to communicate with the head space  18 . Pneumatic gun  30  is preferably a pneumatic gun such as Hitachi Model No. NR-83A which is supported on the lid  12  of the drum by a clamp  32  having three struts  34  pivoted to the clamp at locations  35 . The struts are temporarily anchored at the rim  36  of the drum by toggle couplings  37 . This arrangement precisely locates the pneumatic gun  30  and holds it in engagement with the lid  12 .  
         [0028]    The pneumatic gun  30  has attached thereto a cylinder of compressed air  40  that has a pneumatic line  42  connected through a charging cylinder  44  to the gun  30 . Charging cylinder  44  is connected to an actuator  50  which allows air in the charging cylinder  44  to enter the gun  30  so as to drive a piston downwardly. Since the ports  20  and  22  are configured as punches the piston engages and drives the ports through the lid  12  (as seen in FIGS. 5 and 10). It has been found that the filter and vent ports  20  and  22  can be installed using pneumatic gun pressures in the range of 80 to 120 psi in a fraction of a second so that the escape head gases during installation does not occur, or is so minimal as to be inconsequential.  
         [0029]    In accordance with the present invention, the actuator  50  actuated remotely by a radio frequency from a transmitter  40  so that the technician installing the venting and sampling ports is remote from the installation process and thus is not exposed to hazardous material which may be dislodged or released during the pneumatic pulse which punches the ports  20  and  22  through the lid  12 .  
         [0030]    In accordance with the method of the present invention, the vent port  20  is installed first at a first location radially spaced from the axis  13  of the lid  12 . The pneumatic gun  30  is shifted by loosening the toggle couplings  37  and moving pneumatic gun  30  to a location on the other side of the axis aligned with the vent punch  20 . The toggle couplings  37  are then tightened to fix the pneumatic gun  30  at a second location and again the pneumatic gun  30  is fired, this time to drive the sampling port  22  through the lid  12 . Pneumatic gun  30  is then removed so that the arrangement of filter port  20  and pneumatic port  22  as shown in FIG. 1 occurs.  
         [0031]    A sample of headspace gas is then obtained through the sampling port  22  and analyzed. The analysis is done at a laboratory which may be remote from the location of the 55-gallon steel drum  10  to determine the nature of the head space gas, and to determine whether or not materials in the drum must be repackaged or undergo further processing before shipping to a storage location. Typically, the headspace gas sample is placed in a canister and shipped by overnight express to a laboratory for analysis.  
         [0032]    In order to facilitate the arrangement shown in FIGS. 1 and 2, the filter port  20  shown in FIGS. 3 and 4 and the filter port  22  shown in FIGS. 8 and 9 are configured as punches formed as darts so that they can be rapidly and conveniently forced through and seated within punch holes formed in the lid  12 .  
         [0033]    Referring now to FIGS.  3 - 7  where the filter port  20  is shown in detail, the filter port  20  is inserted first so as to vent head gases in the headspace  18  in order to relieve excessive pressure prior to sampling the head gases, should the headspace gas pressure be excessive. As is seen in FIGS.  3 - 7 , the filter port  20  has an annular body  50  having a shank portion  51 , a head  53 , a first end  52  and a second end  54 . A passage  56  extends centrally through the annular body  50 , the passage having a first opening  58  and a second opening  60 . Inserted with the first opening  58  there is a conical punch point  62  which has pointed portion  64  and a stud portion  66 . The stud portion  66  is received in the first opening  58  of the passage  56  and is held in place by a retaining collar  68 . The retaining collar  68  is made of plastic and overlies exterior threads  70  on the annular body  50  of the punch, as well as overlaying a portion of the conical portion  64  of the punch point  62 .  
         [0034]    As is seen in FIG. 5, as the punch point  62  penetrates the lid  12 , it is stabilized by the stud  66  which is received in the passage  56 . As the filter port  20  is pressed downwardly through the lid  12 , the plastic retaining sleeve  68  is pressed against the threads  70  on the annular body  50  by wall  72  which defines the hole  74  through which shank  51  of the body portion  50  passes. The retaining sleeve  58  is severed by the threads  70  because the retaining sleeve  68  is pushed up against the threads by the wall  72 . Since the retaining sleeve  68  is located adjacent the head  53  of the shank portion  51 , it is carried into the headspace  18  and releases the punch point  62  because its ability to hold the punch point  62  has been negated. Both the punch point  62  and the retaining sleeve  68  then fall away into the headspace  18 , so that the opening  58  in the passage  56  of the body  50  communicates directly with the headspace.  
         [0035]    Positioned around the shank  51  in a groove  76  beneath the head  53  of the vent port  20  is an O-ring  80  made of a long lasting material such as neoprene. The O-ring  80  seats against a top curved portion  82  of the wall  72  that defines the opening  74  to seal the body member  20  with respect to the top surface  84  of the lid  12 . The threads  70  bite into the surface of the wall  72  so as to firmly hold the vent head  20  in place with the O-ring  80  deformed. Thus the vent head  20  is permanently fixed to the lid  12 . If for some reason, it is necessary to remove the vent head  20 , a hex nut portion  88  is formed on the head  53  so that upon counter-clockwise rotation of the vent head  20 , it may be backed out of the opening  74 . This requires considerable torque since the lid  12  is made of steel and the threads  70  of the shank portion bite into the wall  72  of the opening  74  with considerable force.  
         [0036]    In order to minimize the possibility of sparking, the body  50  of the vent port  20  made of an aluminum-bronze alloy, as is punch point  62 .  
         [0037]    The vent head  20  and the sampling head  22  are similarly configured with the exception of the passages  56  and  56 ′ respectively, the passage  56  in the vent head  20  of FIGS.  3 - 7  having a wider step portion  89  at second end  60  configured to receive a filter element  90 . Filter element  90  fits on a shoulder  92  within the passage  56  and has a diameter greater than the passage  56 . Three filter components comprise the filter element  90 ; the first component being a stainless steel screen support  94  which rests on the shoulder  92 ; the second component being a polyethylene woven filter media  96 , and the third component being a HEPA filter  98  i.e. a Gortex filter which blocks entry of moisture but permits escape of vapors. The entire filter element  90  comprised of the three components  94 ,  96  and  98  is less than ⅛ th  inch thick and is held in place by an annular stainless steel retainer  100  which has a friction fit or force fit within the widened step portion  89  of the housing.  
         [0038]    Filter element  90  meets WIPP, WAC and TRUPACT-II SAR section 1.3.5 requirements, i.e.:  
         [0039]    H 2  permeability exceeds 3.7 e-o6 mol/s/mol fraction;  
         [0040]    has greater than 99.97% removal of 0.45 micron DOP, and  
         [0041]    has greater than 60 ml/min @&lt;1″ water column.  
         [0042]    After the vent head  20  is inserted, any head gases which have accumulated in the headspace  18  under pressure pass through the filter  90 . Consequently, pressure within the headspace is reduced to the surrounding atmospheric pressure.  
         [0043]    Referring now more specifically to FIGS.  8 - 12 , the sampling port  22  is then inserted through the lid  12  at a location which is preferably radially spaced from the vent head  20  location as is seen in FIG. 1. As is stated previously, insertion of the sampling port  22  is accomplished by moving the pneumatic gun  30  so that the sampling port  22  is displaced 180° from the venting port  20 . Once the venting port  20  has equalized head space pressure with atmospheric pressure, installation of the sampling port  22  is accomplished without the possible hazard of inserting a closed punch into a closed headspace  18 .  
         [0044]    Referring now to FIGS.  8 - 12 , sampling port  22  has reference numerals are similar to those of the venting port  20 , but with primes. Accordingly, the sampling port  22  is inserted through the lid  12  in substantially the same way as the venting port  20 . A substantial difference in structure between the sampling port  22  and venting port  20  is that the sampling port includes in its passage  56 ′ a silicon septa  110  that seals the passage  56 ′ so that ordinarily gas in the headspace  18  can not pass through the passage  56 ′. The septa seal  110  is disposed between a first set screw  112  that is disposed between the septa  110  and the first open end  58 ′ passage  56 ′. Passage  56 ′ is threaded down to a shoulder  114  which is engaged by a first set screw  112 . The first set screw  112  has a bore  116  therethrough which communicates with the passage  56 ′ and therefore the first opening  58 ′. A second set screw  120  is threaded through the bore  56 ′ after the septa seal  110  is in place. The second set screw  120  is sealed against a shoulder  122  at the second end  60 ′ of the passage  56 ′ by an O-ring  124 . The second set screw  120  is solid all the way through and does not include a bore like the bore  116  through the set screw  112 . Consequently, there is a permanent seal of the passage  56 ′ as long as the second set screw is set in place.  
         [0045]    Referring now to FIG. 13, in order to sample the gas in headspace  18 , the second set screw  120  is backed out by inserting hex wrench in the hexagonal socket  126  to expose the septa seal  110 . Hollow needle  130  is then inserted through the septa  110  and through the bore in the set screw  112  to withdraw test samples from the space  18 . In accordance with known techniques, the hollow needle  130  is connected to a canister such as a Summa® canister for shipping to a laboratory for analysis. After the head gas sample is taken, the set screw  120  is rethreaded into the bore  56 ′ to create what can be a permanent seal unless further sampling is needed, in which case the set screw  120  can be again backed out. Thereafter, the headspace  18  is vented through the aforedescribed venting port  20  in the lid  12 .  
         [0046]    From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.