Abstract:
Spherical storage containers for radioactive materials, such as plutonium oxides and salts, are comprised of coupled hemispheres joined by helical threads or bayonet connections. The spherical storage containers are supported in a barrel by a vertical strut and laterally extending straps or are supported in cylindrically configured frames.

Description:
RELATED APPLICATION 
     This application claims priority of Provisional Application Ser. No. 60/784,758, filed Mar. 23, 2006. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to spherical storage containers. More particularly, the present invention relates to spherical storage containers especially useful for storing radioactive materials, such as plutonium in the form of oxides and salts, as well as in other forms. 
     BACKGROUND OF THE INVENTION 
     Plutonium is a man-made radioactive element which is used as an explosive ingredient in nuclear weapons and as a fuel for nuclear reactors. It has the important nuclear property of being readily fissionable with neutrons and is available in relatively large quantities. Caution must be exercised in handling plutonium to avoid unintentional formation of critical mass. Plutonium in liquid solutions is more apt to become critical than solid plutonium so it is also very important to avoid the unintentional creation of a liquid solution. Since plutonium is considered to be highly carcinogenic, it is important that plutonium in any form be contained and not escape into the surrounding environment where it can be inhaled or otherwise ingested by humans or other living things. Frequently, plutonium oxides and salts are in the form of powders which require very special handling to ensure that particles do not become suspended in the air and that liquid does not come into contact with the powders. Optionally, such containers are vented through high efficiency particulate filters. 
     SUMMARY OF THE INVENTION 
     In view of the aforementioned considerations, it is a feature of the present invention to provide new and improved containers for storage of hazardous materials such as radioactive materials. 
     In view of this feature, spherical containers for hazardous materials comprise a pair of hemispheres having annular rims with complimentary threads for joining the hemispheres. The annular rims are sealed with at least one gasket. An optional self-sealing sample port allows retrieving of a gas sample or allows purging of the container with inert gas. When the hazardous material is nuclear waste, such as solutions or salts containing plutonium, stainless steel or aluminum are the preferred materials from which the containers are fabricated. 
     In accordance with a first embodiment of the invention, at least one of the hemispheres has a handle used to rotate that hemisphere with respect to the other hemisphere in order to join the hemispheres to define a spherical enclosure containing the hazardous material. Preferably, according to the first embodiment, both hemispheres have handles. 
     In a further aspect, each handle is U-shaped and pivoted on its respective hemisphere to fold against the hemisphere after the hemispheres are joined to indicate that the container is ready for storage or shipment. 
     In accordance with a second embodiment of the invention, the spherical container is supported within a surrounding container such as, but not limited to, a barrel by either depending struts or by a frame so that the spherical container is surrounded by space which may contain inert gas. 
     In one aspect of the invention, when the waste material is transuronic waste, such as solutions of salts of plutonium, the container is fabricated of stainless steel or aluminum. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  is a perspective view of a first embodiment of the invention; 
         FIG. 2  is a perspective view of a portion of the present invention showing a threaded connection between a pair of hemispheres that comprise the spherical container of  FIG. 1 ; 
         FIG. 3  is a perspective view showing a self-sealing port used with the spherical container of  FIGS. 1 and 2 ; 
         FIG. 4  is a perspective view of a second embodiment of the present invention showing a spherical container with struts for mounting the container in a surrounding container; 
         FIG. 5  is a perspective view of a third embodiment of the present invention; 
         FIGS. 6 and 7  are photographs showing various parts of the third embodiment with  FIG. 7  showing an upper hemisphere assembled in a frame 
         FIG. 8  is a perspective view of a portion of a lower hemisphere with bayonet lugs and locking pin; 
         FIG. 9  is a perspective view of a portion of an upper hemisphere with bayonet net coupling lugs and the locking pin from  FIG. 8  shown in position, and 
         FIG. 10  shows a sampling portion between axial and radial seals. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIG. 1  there is shown a first embodiment  20  of a spherical container  22  which is useful for storing hazardous waste and especially useful for storing a transuranic hazardous waste such as solutions and salts of plutonium. Spherical container  22  has a first hemisphere  24  and a second hemisphere  26  that are joined by a coupling  28 . The coupling  28  may be either a bayonet type coupling or an illustrated threaded coupling. 
     The first hemisphere  24  has a U-shaped handle  28  pivoted thereto on a pair of flanges  30  while the second hemisphere  26  has a U-shaped handle  32  pivoted thereon by a pair of flanges  34  attached thereto. By gripping one of the handles  28  or  32  in one hand and gripping the other handle in the other hand, the hemispheres  24  and  26  may be rotated relative to one another to either thread the hemispheres together with a threaded coupling  28  or to cam them together with a bayonet-type coupling. 
     Referring now to  FIG. 2  where an elevation of the coupling  28  is shown enlarged, it is seen that the first hemisphere  24  has an L-shaped annular rim  40  projecting therefrom and the second hemisphere  26  has a block type annular rim  42  projecting therefrom, it is seen that the L-shaped annular rim receives the block, type annular rim therein. As the second hemisphere  26  is rotated with respect to the first hemisphere  24 , the block-type annular rim  42  advances into the L-shaped annular rim  24  to compress an O-ring  44  that is received in a slot  46  in the block-type annular ring  42 . In the illustrated embodiment, spherical threads  48  on the axially extending portion  50  of the L-shaped annular rim  40  are advanced in spherical grooves  52  formed in the block shaped annular groove  42 . When the exposed end  54  of the annular rim  42  abuts the shoulder  56  of the L-shaped annular rim  30 , the O-ring  44 , which is preferably a Viton O-ring, is compressed to affect a very reliable seal. The spherical threads  48  and spherical grooves  52  are precision machined into the rims  40  and  42 . 
     As is seen in  FIG. 3 , in combination with  FIG. 1 , an optional self-sealing sample port  60  is disposed through the wall  62  defining the first hemisphere  24 . The sample port allows retrieving a gas sample from the space  63  which contains a hazardous material, such as transuranic waste and/or allows purging of the space  53  with inner gas. 
     A sealable container  22  is one embodiment comprised of two 14-guage stainless steel hemispheres  24  and  26  spun formed to an 8-inch inside diameter. The fold down handles  28  and  32  are lanes for fast reliable closure and provide a visual verification of seal when folded over. The approximate weight of the empty spherical container  20  is about seven pounds. 
     Referring now to a second embodiment of the invention shown in  FIG. 4 , it is seen in  FIG. 4  that a spherical container  22 ′ has a cylindrical aluminum tube  70  extending from a lower hemisphere  72 . The upper hemisphere  74  which has been joined to the lower hemisphere  72  by coupling rim portions  76  have three straps  80 ,  81  and  82  extending vertically therefrom. The straps  80 - 82  are L-shaped with each strap having a long leg  83  and a short leg  84 . The long leg  83  is bolted to an exterior surface of the coupling ring  76  while the short leg has screw holes for bolting to a container in which the spherical container  22 ′ is mounted. The cylindrical aluminum member  70  is a strut which supports the container from the bottom in a barrel, while the L-shaped brackets can be bolted to a top rim or lid of the barrel. 
     A first sampling port  85  allows one to sample the interior of the spherical container  22 ′ while the second port  86  allows one to sample the sealing area defined by the coupling  76 . 
     A handle  87  is pivoted on arculate reinforcements fixed to the top surface of top hemisphere  74 . U-shaped handle  87  can be disconnected from the top hemisphere  74  by pulling a locking pin  89 . 
     Referring now to  FIG. 5  there is shown a third embodiment of the invention wherein the spherical container  22 ″, formed of lower hemisphere  24 ″ and an upper hemisphere  26 ″, and is caged in a cylindrical frame assembly  90  for mounting in an outside container such as a barrel, illustrated by the dotted lines  92 .  FIG. 6  shows elements of the frame assembly  90  used to support the spherical container  22 ′ of  FIG. 5 . The frame  90  has a lower frame assembly  94  and an upper frame assembly  96 . The lower and upper assemblies  94  and  96  are configured of nested brackets that are fixed to a lower spoked rim  100  and upper spoked rim  102 . A lower spoked rim  100  is positioned at the lower end  104  of the barrel  92  and the upper spoked rim  102  is positioned adjacent the top or lid of the barrel  92 . 
     Referring now more specifically to  FIGS. 6 and 7 , the upper frame assembly  96  is assembled to the upper rim  102  and the lower frame assembly  94  is shown disassembled and adjacent to the lower rim  100 . The lower and upper frame assemblies  94  and  96  are substantially identical. As is apparent from  FIG. 6 , brackets  110 ,  112 ,  114  and  116  forming frame assemblies  94  and  96  have complementary slots  120 ,  122 ,  124 ,  126  and  128  which receive brackets  110 - 116  so as to nest to brackets together in interlocking relationship. As is seen with the assembled upper frame assembly  96  on the upper rim  95 , the brackets  110 - 116  have upper ends which are anchored by screws to the spokes of the lower rim  95 . As is seen in  FIG. 7 , the brackets  110 - 116  of the upper frame assembly  96  have lower ends which are bolted to the upper hemisphere  26 ″ of the cylindrical container  22 ′ at an upper rim portion  132 . Referring back to  FIG. 5 , the lower hemisphere  24 ″ receives a quantity of waste material such as transuranic waste and the upper hemisphere  26 ″ is attached rotatably to the lower hemisphere utilizing a bayonet connection  144  ( FIGS. 8 and 9 ). This is accomplished by a spanner  146  that attaches to the upper hemisphere and rotates the upper hemisphere through a relatively small angle of about 20°. 
     The brackets  94  and  96  of each frame assembly  94  and  96  shown in  FIG. 6  have arcuate, inwardly facing surfaces  147  which abut the hemispherical outer surfaces  148  and  149  of the hemispheres  24  and  26  when the brackets are assembled as shown in  FIGS. 7 and 5 . 
     Referring now to  FIGS. 8 and 9  it is seen that the lower hemisphere  24 ″ has projecting lugs  150 , wherein the projecting lugs  150  have lower surfaces  152  which are beveled at a 30° angle to help center cooperating inwardly projecting lugs  154  (see  FIG. 9 ) of the upper hemisphere  26 .″ The lugs  154  of  FIG. 9  have upper beveled surfaces  156  which are also angled to cooperate with the surfaces  152  so as to center the upper hemisphere  26 ″ with respect to the lower hemisphere  24 ″. The surfaces  156  and  152  are also arcuate portions of a helix so that as one rotates the upper hemisphere  26 ″ with respect to the lower hemisphere  24 ″, the upper hemisphere is cammed downwardly toward the lower hemisphere. The bayonet connection  144  illustrated in  FIGS. 7 ,  8  and  9  allows one to make a tight fitting connection with only 20° of rotation using the spanner  146  of  FIG. 7 . 
     Referring now to  FIG. 10  there is shown a section through the assembly of the upper hemisphere  24 ″ and the lower hemisphere  26 ″, wherein the upper hemisphere has a lip  160  having the projecting lugs  156  thereon which cooperate with the projecting lugs  150  on the lower hemisphere  24 ″ to positively lock the upper hemisphere  26 ″ to the lower hemisphere  24 ″ as the hemispheres are rotated with respect to one another. As is seen in  FIG. 10 , there are two O-ring seals, a compression seal  170  positioned in an upwardly opening groove  172  in the upper edge  174  of the lower hemisphere  24 ″ and a radial seal  180  that is positioned in a radially opening groove  182  positioned below the axial seal  170  and slightly outboard of the axial seal  170 . As the upper hemisphere  26 ′ is drawn down by interaction of the lugs  150  and  154 , the upper seal  170  is compressed to prevent radial leakage of gases or fluids from the space in the spherical container  22 ″ while the radial seal  180  prevents axial leakage of fluid which may have leaked between the seal  170  and the lower edge of shoulder  173  of the upper hemisphere  26 ″. 
     As is also seen in  FIG. 10  there is a port  190  which allows sampling of the area or space between the upper axial seal  170  and the lower radial seal  180  to determine is there is fluid by passing the upper radial seal. The port has a sampling insert  192  therein that has an opening  193  thereto that is aligned with a self-sealing plug so that a hypodermic sampling needle may be inserted through the insert  92  to sample gas in the area  196 . 
     Referring back to  FIG. 5 , another self-sealing sampling port  200  is provided into the top of upper hemisphere  26 ″ so that gas therein may be sampled with a hypodermic needle. 
     Optionally a filtered vent may be installed in the upper hemisphere  26 ″ of the spherical container  22 ″ to vent gases accumulating in the container. 
     In order to lock the upper hemisphere  26 ″ with respect to the lower hemisphere  24 ″ after the upper hemisphere has been rotated using the scanner  146 , a self-locking pin  210  is used. The self-locking pin  210  is spring projected and is initially cammed down upon rotating the hemispheres with respect to one another. In order to open the hemispheres, the locking pin is dislodged by pulling on a loop  214 . 
     From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing form the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.