Patent Publication Number: US-2006016856-A1

Title: Apparatus and method for sealing a container

Description:
RELATED APPLICATION  
      This application is a continuation-in-part of U.S. patent application Ser. No. 10/896,411, filed on Jul. 21, 2004, entitled “Grinding Assembly, Grinding Apparatus, Well Joint Defect Repair System, and Method.” 
    
    
     GOVERNMENT RIGHTS  
      This invention was made with Government support under Contract DE-AC07-99ID13727 awarded by the U.S. Department of Energy. The Government has certain rights in the invention. 
    
    
     TECHNICAL FIELD  
      The present invention relates to an apparatus for sealing containers, and a method for implementing same, and more specifically to an apparatus which includes a rotating carousel which carries a plurality of work stations and which are operable to remotely seal a canister carrying hazardous waste in a fashion not possible heretofore.  
     BACKGROUND OF THE INVENTION  
      The nuclear industry has long struggled with the issues surrounding the handling and disposal of nuclear waste.  
      It should be understood that hazardous materials, such as nuclear waste, are typically sealed into metal containers for long term storage, and to prevent such materials from escaping into the immediate ambient environment. Heretofore, canisters or containers of this type were sealed by personnel in environments called “hot cells,” that is, rooms having thick walls and windows where work can be safely done with radioactive materials that might be detrimental to humans. Notwithstanding the safeguards that have been developed, the present system for handling nuclear waste, and sealing the same in such containers has been less than ideal.  
      In addition to the problems of potential exposure of personnel to the hazardous waste being sealed in such storage containers, there are further problems in the prior art practices and which concern whether the containers, once sealed, potentially have defective seals, and which could readily fail or open, once the containers are moved into a suitable storage facility to expose the contents of such containers to the ambient environment.  
      It would be desirable therefore to have an apparatus and method for sealing a container, and which provides a convenient means whereby containers of this sort could be readily sealed, inspected, and otherwise repaired in the event that a defective seal is detected during the sealing process.  
     SUMMARY OF THE INVENTION  
      A first aspect of the present invention relates to an apparatus for sealing a container and which includes a first work station which supports a container to be sealed; a moveable carousel which rotates about the first work station; a second work station borne by the moveable carousel, and which creates a seal on the container; a third work station borne by the moveable carousel, and which inspects the seal made by the second work station and identifies any defect in the seal; and a fourth work station borne by the moveable carousel, and which removes a region of the seal which includes the identified defect, and wherein the carousel selectively rotates to a position where the second work station can reapply the seal in the region of the seal which has been removed, and wherein subsequent to the reapplication of the seal, the carousel selectively rotates to a position where the region of the seal which has been previously removed, and reapplied is reinspected to identify any remaining defects in the seal.  
      Another aspect of the present invention relates to an apparatus for sealing a container which includes a first work station for supporting a metal container in a working position, and which encloses a material which emits hazardous radiation; a radiation shield which surrounds the first work station, and wherein a portion of the metal container extends above the radiation shield; a moveable carousel which selectively rotates about the first work station; a second work station, borne by the moveable carousel, and which mounts a remotely controllable welding apparatus for forming a welding bead which seals the container, and wherein the welding apparatus is located in a position above the radiation shield when the welding bead is being formed, and is further moveable to a protected position below the radiation shield when the welding apparatus is not forming the welding bead, and wherein the moveable carousel selectively moves the welding apparatus around the metal container to form the welding bead; a third work station, borne by the moveable carousel, and which is positioned in spaced relation relative to the second work station, and wherein a remotely controllable inspection device is borne by the third work station and is positioned above the radiation shield, and is further configured to detect a defect in the welding bead formed by the second work station when positioned above the radiation shield, and is further moveable to a protected position below the radiation shield when the inspection device is not being employed to detect a defect in the welding bead; a fourth work station, borne by the movable carousel, and which is positioned in spaced relation relative to the first and second work stations, and wherein a remotely controllable removal device is borne by the fourth work station, and is positioned above the radiation shield, and is configured to remove, at least in part, any defect which has been detected in the welding bead formed by the second work station, and is further moveable to a protected position below the radiation shield when the removal device is not in use; and a computer borne by the carousel and which is substantially protected from the hazardous radiation emitted by the material enclosed within the metal container by the radiation shield, and wherein the computer is coupled in controlling relation relative to the second, third and fourth work stations.  
      Another aspect of the present invention relates to a method for sealing a container and which includes providing a container to be sealed and which encloses waste material which emits hazardous radiation; providing a carousel which selectively rotates about the container to be sealed; providing a device which is borne by the carousel, and which is configured to seal the container; and operating the carousel, and the device, from a remote location to seal the container, and prevent an operator from being exposed to the emitted hazardous radiation.  
      Yet further, another aspect of the present invention relates to a method for sealing a container and which includes providing an enclosure which shields an operator from hazardous radiation; providing a first work station within the enclosure, and which supports a metal container which must be sealed, and which encloses a material that emits hazardous radiation; providing a carousel which selectively rotates about the first work station; providing a second welding station, mounted on the carousel, and which is configured to seal the metal container by depositing a welding bead on the metal container; providing a third inspection station, mounted on the carousel, and which inspects the welding bead formed on the metal container to detect significant flaws in the welding bead; providing a fourth removal station, mounted on the carousel, and which removes, at least in part, any of the significant flaws found in the welding bead; providing at least one controller which is controllably coupled with the carousel, second, third, and fourth repair stations; and individually operating the carousel, second, third and fourth work stations, from a location which is remote from the enclosure, and in a fashion so as to substantially seal the hazardous material within the metal container by means of a welding bead which has substantially no significant flaws.  
      These and other aspects of the present invention will be discussed in greater detail hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Preferred embodiments of the invention are described below with reference to the following accompanying drawings. Some surfaces have been removed to show the structure thereunder.  
       FIG. 1  is a perspective, greatly simplified view of the apparatus for sealing a container of the present invention.  
       FIG. 2  is a perspective, side elevation view, of an apparatus for sealing a container of the present invention.  
       FIG. 3  is a greatly simplified schematic view of the control system employed with the apparatus and method of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8).  
      The apparatus and method for sealing a container of the present invention is generally indicated by the numeral  10  and is seen in  FIG. 1  and following. As shown therein, the apparatus  10  is positioned or otherwise located on a supporting surface generally indicated by the numeral  11 . The apparatus is enclosed within a “hot cell” which is also generally indicated by the numeral  12  and which is utilized to contain or otherwise confine hazardous, electromagnetic radiation from escaping into the ambient environment. Such “hot cells” are well known in the art, and typically include rather thick floors, walls, and ceilings and which are useful in confining or otherwise restraining emitted hazardous radiation so that it does not escape into ambient environment and potentially harm personnel that are nearby. In this regard, the “hot cell” has a floor  13  and sidewalls  14  which extend generally normally upwardly therefrom. A roof or ceiling  15  is provided and is sealably mated with the surrounding sidewalls  14 . As seen in  FIG. 1 , an electrical power conduit  16  is provided and which passes through a channel formed in the floor in order to provide electrical power for use by the apparatus  10 . As seen in  FIG. 1 , the apparatus  10  includes a rotatable carousel  20  which carries a plurality of work stations which will be discussed in greater detail hereinafter.  
      The rotatable carousel  20  has a top surface  21  which is positioned in spaced relation relative to the floor  13  of the hot cell. The rotatable carousel  20  further has a plurality of sidewalls  22  which extend generally perpendicularly downwardly relative to the top surface  21 , and defines a cavity  23  therein. Mounted in the cavity of the rotatable carousel  20  is a computer  24  which is coupled to the electrical power conduit  16  and further is coupled in controlling relation relative to the work stations which will be described hereinafter. Still further, a plurality of controllers and other power supplies  25  are also received in the cavity  23  and are coupled to and controlled by the computer  24 . The computer is directly controlled by way of wireless communication to a distant work station  26  as seen in  FIG. 3 . This permits an operator (not shown) to communicate by wireless communication to the computer in order to give it commands and to otherwise control the apparatus and method of the present invention  10 . The rotatable carousel  20  includes a motor (not shown) and which drives the rotatable carousel in a given direction. The electrical power supplied by the electrical power conduit  16  enters the rotatable carousel  20  by way of slip rings which are mounted below the carousel. In the arrangement as shown, the electrical power conduit  16  provides 480 volts, 3 phase power provided through these slip rings (not shown) and then transformers (not shown) mounted within the cavity  23  steps this same voltage down to levels required for the computer, control hardware and other subsystems utilized for each of the workstations which may include other computers, motor controllers, power supplies, and signal processors as the needs arise. In the arrangement as shown, hardware and associated subsystems mounted in the cavity  23  are sealed and shielded against radiation and contamination as will be described in greater detail hereinafter.  
      A first work station  40  is best seen by reference to  FIGS. 1 and 2 . The first work station is located substantially centrally relative to the rotatable carousel  20  and substantially along the rotational axis of same. The first work station as seen in  FIG. 2 , supports a container  41  to be sealed, and which contains waste material  42  as previously described. The container  41  enclosing the waste material  42  and which emits the hazardous radiation, is fabricated from metal, and includes a bottom portion  43  and which defines a cavity  44 . Still further, the container includes a cover  45  which matingly cooperates with the bottom portion, and which completely encloses the waste material  42  which emits the hazardous radiation within the cavity. As seen in  FIG. 2 , the bottom portion  43  and the cover  45  when oriented in mating relation together define a seam  46  therebetween.  
      As best seen by reference to  FIG. 2 , a radiation shield  50  is positioned thereabout the container in the first work station  40 . The radiation shield provides a means by which devices employed in the individual second, third and fourth work stations can be moved from a first sheltered position below the radiation shield to a second exposed position above the radiation shield. Once above the radiation shield, the various devices employed in the second, third and fourth work stations, as will be described below, may be moved into contact with the container  41  to achieve the benefits which will be described in greater detail hereinafter. As seen in  FIG. 2 , a portion of the metal container  41  extends above the top of the radiation shield  50  thereby permitting access to same by the second, third and fourth work stations.  
      A second work station  60  is provided, and is positioned on the top surface  21  of the rotatable carousel  20 . The second work station  60  includes an upright tower  61  which extends generally normally upwardly relative to the top surface of the carousel, and further mounts a moveable arm  62  which moves along the tower so that the moveable arm  62  may be positioned at a location above the radiation shield  50 . The moveable arm has a first portion  63  which is moveably affixed to the tower  61  and a second portion  64  which can be extended outwardly relative to the first portion and which mounts on its distal end, a welding assembly  65 . As should be understood, the second work station creates a seal between the bottom portion  43  and the cover  45  of the container  41 . More specifically, if the container, is fabricated from a metal, then the second work station is operable to provide a welding bead which is deposited in the seam  46  which is defined between the bottom portion of the container and the cover. Once deposited, the welding bead substantially sealably joins the bottom portion of the container  43  and the cover  45  together. A welding device or assembly  65  of the type that may be employed in the second work station  60  is seen in various U.S. Patents such as U.S. Pat. No. 6,178,819 and U.S. Pat. No. 4,712,722, both of which are incorporated by reference herein. It should be understood that the welding device or assembly employed in the second work station  60  may also include an assembly for the concurrent inspection of a partially completely weld such as what is shown in these earlier patents. Still further, this concurrent inspection may include an ultrasonic generator which generates an ultrasonic signal which is passed, at least in part, through the partially completed weld. As seen in  FIG. 2 , the second work station  60  which mounts the remotely controllable welding apparatus or assembly  65  for forming a welding bead is located in a position above the radiation shield  50  when the welding bead is being formed, and is further movable to a protected position below the radiation shield when the welding apparatus  65  is not forming a welding bead. Still further, it should be understood that the moveable carousel  20  is operable to be selectively moved such that the welding apparatus  65  can be selectively rotatably moved around the container  41  to form the welding bead in the seam  46 . Still further, it will be recognized from a study of the drawing that the various work stations as described herein, are moveable relative to the container  41  in the X and Y axes. It being appreciated that the moveable carousel  20  causes movement of the respective work stations in the Z axis.  
      The apparatus and method of the present invention  10  includes a third work station which is generally indicated by the numeral  70 , and which is mounted on the top surface  21  of the rotatable carousel  20  and which is further disposed in spaced relation relative to the second work station  60 . The third work station  70  which is borne by the moveable carousel  20 , inspects the seal, or welding bead as formed by the second work station and is additionally operable to identify any defects in the seal which would permit the escape of any of the hazardous material  42  which is enclosed within the container  41 . The third work station  70  has a tower  71  which mounts a moveable arm  72  which is operable to move along the tower. Still further, a motor  73  is mounted at the base of the tower and is operable to drive the moveable arm  72  to a position where it can be located above the radiation shield  75 . The moveable arm  72  carries an inspection assembly  74  which may take on several different forms including one or more inspection tools which are selected from the group which includes ultrasonic energy, eddy current, laser and visual inspection devices. These are all well known in the art and are outlined in many U.S. Patents including U.S. Pat. No. 6,178,819, 4,712,722 and 6,365,873 to name a few. The aforementioned patents are all incorporated by reference herein. Again as was described with respect to the second work station  60 , the remotely controllable inspection device  74  is positioned above the radiation shield  50  and is further configured to detect a defect in the welding bead formed by the second work station  60  when positioned above the radiation shield. Still further, the inspection device  74  is moveable to a protected position below the radiation shield  50  when the inspection device is not being employed to detect the defect in the welding bead.  
      Mounted on the top surface  21  of the carousel  20  and spaced from the third work station  70 , is a fourth work station which is generally indicated by the numeral  80 . The fourth work station removes a region of the seal formed by the second work station  60  and which includes any defect as previously identified by the third work station  70 . In this regard, the fourth work station includes a tower  81  including a moveable arm  82 . A motor  83  is mounted at the base of the tower  81  and selectively drives the moveable arm  82  along the tower. The fourth work station mounts a repair assembly, here shown as a remotely controllable grinder  84 , and which is configured to remove, at least in part, any defect which has been detected in the welding bead formed in the seam  46  and which has been previously formed by the second work station  60 . Still further, much like the second and third work stations, the remotely controllable grinder or repair assembly  84  is moveable from a protected position below the radiation shield  50 , when the device is not in use, and further is moveable to a position above the radiation shield such that repairs can be made. In the arrangement as shown in  FIG. 2 , the remotely controllable repair assembly, here shown as a grinder  84 , removes a region of the welding bead having the defect as previously identified by the third work station  70  by implementing a grinding profile which is supplied by the computer  24  to the remotely controllable grinder  84 . This process is described more fully in co-pending application Ser. No. 10/896,411, and which is incorporated by reference herein.  
      The apparatus  10  as shown, and described is operable to implement a method for sealing a container  41  as described, below. In this regard, the method for sealing the container  41  includes a first step of providing an enclosure, here illustrated as a hot cell  12 , and which shields a remote operator positioned at a work station  26  from hazardous radiation. The method further includes a step of providing a first work station  60  within the enclosure  12 , and which supports a metal container  41  which must be sealed and which encloses a material  42  that emits hazardous radiation. The method further includes a step of providing a carousel  20  which selectively rotates about the first work station  60 . The method further includes an additional step of providing a second welding station  70  mounted on the carousel  20  and which is configured to seal the metal container  41  by depositing a welding bead on the metal container. After providing a welding bead on the metal container, the method further includes a step of providing a third inspection station  70  and which inspects the welding bead formed on the metal container to detect significant flaws in the welding bead. This third inspection station  70  may employ a number of different inspection tools selected from the group comprising ultrasound, eddy current, laser and/or visual, as necessary, to detect any defects or deficiencies in the welding bead. After the step of inspecting the welding bead, the method includes a step of providing at least one controller  25  which is coupled with the carousel  20 , and the second, third and fourth repair stations  60 ,  70  and  80 , respectively. Thereafter, the method includes a step of individually operating the carousel  20  and second, third and fourth work stations  60 ,  70  and  80  from a remote location or work station  26  ( FIG. 3 ) which is remote from the enclosure  12 , and in a fashion so as to substantially seal the hazardous material  42  within the metal container  41  by means of a welding bead which has substantially no significant flaws. In the method of the present invention, and subsequent to the removal of any portion of the welding bead which has been identified as being defective and has been thereafter removed by the fourth work station  80 , the method further includes an additional step of reapplication of the welding bead by the second work station  60 . In this regard, the carousel  20  selectively rotates to a position where the region of the welding bead which has been previously removed by the fourth work station  80  may be reapplied and is thereafter reinspected by the third work station  70  to identify any remaining defects in the seal or welding bead. As earlier discussed, a remote operator, working from a work station  26  may, by means of wireless communication which is indicated, very generally, by the numeral  90 , can communicate with the computer  24  in order to provide directions for the effective utilization of the assembly  10  and the effective sealing of the hazardous waste material  42  in the container  41 .  
     OPERATION  
      The operation of the described embodiment of the present invention  10  is believed to be readily apparent and is briefly summarized at this point.  
      An apparatus for sealing a container  10  of the present invention includes a first work station  40  for supporting a metal container  41  in a working position and which encloses a material  42  which emits hazardous radiation. A radiation shield  50  surrounds the first work station  40 , and as seen in  FIG. 2 , a portion of the metal container extends above the radiation shield. A moveable carousel  20  is provided and which selectively rotates about the first work station  40 . A second work station  60  is borne by the moveable carousel, and which mounts a remotely controllable welding apparatus or assembly  65  for forming a welding bead which seals the container  41 . The welding apparatus or assembly is located in a position above the radiation shield  50  when the welding bead is being formed, and is further moveable to a protected position below the radiation shield when the welding apparatus is not forming the welding bead. The moveable carousel  20  selectively moves the welding apparatus around the metal container to form the welding bead. A third work station  70  is borne by the moveable carousel  20 , and is positioned in spaced relation relative to the second work station  60 . A remotely controllable inspection device  74  is borne by the third work station  70  and is positioned above the radiation shield, and is further configured to detect a defect in the welding bead formed by the second work station  60  when positioned above the radiation shield, and is further moveable to a protected position below the radiation shield  50  when the inspection device is not being employed to detect a defect in the welding bead. A fourth work station  80  is borne by the movable carousel  20 , and which is positioned in spaced relation relative to the first and second work stations  40  and  60 , respectively. A remotely controllable removal device, here shown as a grinder  84 , is borne by the fourth work station  80 , and is positioned above the radiation shield  50 , and is configured to remove, at least in part, any defect which has been detected in the welding bead formed by the second work station  40 , and is further moveable to a protected position below the radiation shield  50  when the removal device is not in use. A computer  24  is provided and is borne by the carousel  20  and which is substantially protected from the hazardous radiation emitted by the waste material  42  which is enclosed within the metal container  41  by the radiation shield  50 . The computer  24  is coupled in controlling relation relative to the second, third and fourth work stations  60 ,  70  and  80 , and further is controllably coupled to the rotatable carousel  20  in order to control the rotation of the carousel and therefore the position of the second, third and fourth work stations relative to the container  41  to be sealed. This relationship is seen in  FIG. 3 .  
      Therefore it will be seen that the method and apparatus  10  of the present invention provides a convenient means by which hazardous waste may be enclosed within a container, and effectively sealed thereby preventing the escape of the hazardous waste or radiation produced by same into the ambient environment.  
      In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.