Abstract:
The present invention in one of its preferred structural embodiments comprises a plurality of generally rectangular radiation attenuating panels having rollers mounted on the bottom of each panel and rollable in a lower track mounted on a base such as the concrete floor of a building for movement of each panel along the lower track to a designated position to isolate workers in a particular area from a source of harmful radiation, wherein an upper track is mounted on a rigid structure adjacent upper portions of the panels for laterally engaging in a guiding manner upper guide elements on the upper portions wherein the upper track has substantially the same longitudinal configuration (tracking axis) as the lower track.

Description:
[0001]    This application claims priority under 35 U.S.C. 119(e)(1) based on Applicants Provisional U.S. Patent Application Ser. No. 60/622,741 filed Oct. 28, 2004 and titled “RADIATION PROTECTION SHIELD”. 
     
    
     BACKGROUND OF THE INVENTION 
     Field 
       [0002]    This invention concerns a radiation protective shield structure which can be made transportable and which can be set up at various work sites within or without a building at which sites workers could otherwise be exposed to harmful radiation during maintenance or inspection of equipment or installations or other operations. 
         [0003]    The available work time per individual worker in a high radiation area is a function of two factors, the actual radiation level measured in the work area and the amount of radiation dose that the worker can safely be exposed to. The time available for an individual to be in the radiation area is called the “stay time”. When the work to be accomplished requires a period of time greater than the “stay time”, an additional worker must be added. Where the radiation level is very high, the “stay time” may be reduced to minutes and many workers would be required. Before an individual can start the work assigned, a lengthy Rad Worker training program must be completed and also generally, a job specific training program. The training may take several days to make the individual available for a few minutes actual work. 
         [0004]    A principal object therefore of this invention is to provide a shield, preferably one which is transportable and readily adapted for overall size expansion, between the work area and a high radiation source of e.g., alpha, beta, gamma, mention, or the like. The lower radiation levels, resulting from the use of the shield will allow a few individuals to accomplish the work that would have required a large number of workers without the shield. After work and/or inspections are complete, the shield can be partially or completely removed, or moved to another work site. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention in one of its preferred structural embodiments comprises a plurality of generally rectangular (includes square) panels each of which is of a designed thickness having an inner lead or other radiation attenuating core encased (canned) in a steel (includes stainless) shield and having a tracking axis, two or more rollers mounted on the bottom of each panel, a lower track mounted on a base such as the concrete floor of a building for rollably supporting said rollers for movement of each said panel along said lower track to a designated position, said lower track being longitudinally configured to allow said panels to be rolled to positions to isolate workers in a particular area from a source of harmful radiation, first guide rail means on said lower track for maintaining proper alignment of said rollers with said lower track, an upper track mounted on a rigid structure adjacent upper portions of said panels and having second guide rail means for laterally engaging in a guiding manner upper guide elements on said upper portions of said panels, said upper track having substantially the same longitudinal configuration (tracking axis) as said lower track. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The invention will now be understood further from the following description and drawings of preferred embodiments wherein the various structures are not necessarily to scale or in proportion to each other, and wherein: 
           [0007]      FIG. 1  is a perspective side view of complete present shield assembly of the type installed within a building and supported by brackets to permanent wall portions of the building structure; 
           [0008]      FIG. 2  is a perspective side view of a complete present shield assembly of the type which is self supporting and which is adapted for use within or outside a building; 
           [0009]      FIG. 3  is a perspective view of the roller and adjacent structure of  FIG. 2  taken within the encircled area in  FIG. 2 ; 
           [0010]      FIG. 4  is a side view of one useful type of panel with portions broken away for clarity; 
           [0011]      FIG. 5  is an enlarged lateral cross-section of the panel of  FIG. 4  taken along line  5 - 5  in  FIG. 4 ; 
           [0012]      FIG. 6  is a top view of the panel of  FIG. 4  taken along line  6 - 6  therein and showing portions of the upper track guide rail means and vertical axis mounted rollers (upper guide elements) on the panel; 
           [0013]      FIG. 7  is a partially cross-sectional view of the upper portion of a panel with upper guide elements (rollers) and portions of the upper track shown; 
           [0014]      FIG. 8  is a top perspective view of a present shield assembly affixed in a typical manner to internal wall portions of a building and surrounding a section of a radiation source; 
           [0015]      FIG. 9  is a side view of a series of positioned panels wherein the mounting support for the panels is provided by inner I-beam structure of the building; 
           [0016]      FIG. 10  is a partially cross-sectional lateral view of one type of thrust bearing mounting for the caster type rollers; 
           [0017]      FIG. 11  is a view as in  FIG. 10  showing a variation of the thrust bearing roller mounting; 
           [0018]      FIG. 12  is a side view of a panel of  FIG. 9  showing details of a latching mechanism (dotted outlines in  FIG. 9 ) useful for connecting the panels to each other once in position; 
           [0019]      FIG. 13  is a view taken in the direction  13 - 13  in  FIG. 12 ; 
           [0020]      FIG. 14  is a lateral cross-sectional view of the lower track showing one embodiment of the track leveling means; 
           [0021]      FIG. 15  is a lateral cross-sectional view of a variation of the lower track and complementary roller; 
           [0022]      FIG. 16  is a partially cross-sectional view of a variation of the bracket structures of  FIG. 1 ; 
           [0023]      FIG. 17  is a top down view taken along line  17 - 17  in  FIG. 16 ; 
           [0024]      FIG. 18  is a cross-sectional view taken along line  18 - 18  in  FIG. 4 ; 
           [0025]      FIG. 19  is a partially cross-sectional view of a foot portion of a lateral stabilizer arm showing a leveling means for the arm; 
           [0026]      FIG. 20  is an enlarged perspective view of the upper track mounting bracket and vertical adjustment means; 
           [0027]      FIG. 21  is a partially cross-sectional perspective view of the panel of  FIG. 1 ; 
           [0028]      FIG. 22  is an enlarged view of the encircled structure in  FIG. 21 ; 
           [0029]      FIG. 23  is an enlarged partially cross-sectional view of a preferred type of wall clamping structure for the upper track wall mounting brackets; 
           [0030]      FIG. 24  is a lateral cross-sectional view of a variation of the upper track and the upper guide elements (rollers) of the panels; and 
           [0031]      FIG. 25  shows a manual steering mechanism for the caster wheels as exemplified by a variation of the caster structure of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    Referring to the drawings and claims herein, the present shield assembly or structure generally designated  20  consists basically of a lower track  22 , an upper track  24  and support means  26  therefor, a lower track support means  28  and the shield panels  30 . All structural components of the shield assembly are steel or stainless steel, and, of course are sufficiently strong to rollably support panels which may weigh several thousands of pounds. Also, in the various figures equivalent structures may be numbered the same. 
         [0033]    The lower track typically rests on the concrete floor  32  of a building and supports the shield structure and provides the path (tracking axis) which the shield panels will follow. The tracks  22  and  24  may be straight or have bends to guide the shield panels into the most advantageous position and  22  is provided with leveling means  34  if required. 
         [0034]    The upper track  24  follows the path of the lower track and is supported overhead by support means  26  and guides the upper end of the shield panels and holds the panels substantially vertical. The upper track  24  may have more than one elevation, as shown in  FIG. 1  to accommodate plant work area interferences requiring different height and or size panels. Each panel is fitted with two or more wheels or rollers  36  which can be of any configuration to fit the shape of the lower track, e.g., flat or crowned or grooved or the like and can be fixed axially or of the caster type as shown, e.g., in  FIG. 5 . Provision to steer the caster type wheels may be incorporated as shown in  FIG. 25 . The wheels may also be powered, preferably by electric motors. The panels are of an appropriate shielding thickness, height, width and of proper shield material for the project at hand and is selected from material such as lead or other radiation attenuating material including concrete and steel. If the shield material is lead, an outer shell of steel, carbon steel or stainless steel preferably is provided to cover and seal any exposed lead. The panels lap over each other at their edges  38  and  40  as shown in  FIGS. 6 and 18  to prevent radiation from streaming though the joint. The panels also have lifting provisions such as winch cable hook eyes  45  at the top. A latch mechanism as shown in  FIGS. 12 and 13  can be provided to connect panels to adjacent panels in their operative positions and locations. The panels can be painted a light reflecting color to enhance the lighting in the work area. 
         [0035]    The operational sequence of the invention is as follows: 
         [0036]    The lower track is moved into place. It is leveled and secured to the floor if necessary. The upper track is then positioned, supported and secured directly above the lower track with their tracking axes aligned. Next the first shield panel is positioned vertically and placed on the lower track. It is advanced until the upper guide rollers are engaged in the upper track. The first panel is then advanced down the track to the required position. Additional shield panels are added as required. The entire track may be loaded with shield panels to develop a shield wall. One or more panels may be placed on the track in an assembly to shield a specific area. The panel assembly may be repositioned on the track as required. 
         [0037]    When the shield panels are no longer required, the panels may be removed, followed by the upper and lower track assemblies. In a further embodiment of this invention, the upper and lower track assemblies would be attached to each other and appropriately braced to make the movable shield free standing as shown in  FIGS. 2 and 19 . Hoisting equipment for lifting the shield panels and placing them on the track could include overhead traveling electric hoists, chain falls, electric winches, fork lift or other such equipment, and where feasible could be incorporated into the shield system itself or could be an independent unit or part of the track assembly. 
         [0038]    Referring further to the drawings, in particular  FIGS. 1 ,  8 ,  16 ,  17 ,  20  and  23 , many industrial installations wherein radioactive equipment or materials generally designated  42  in  FIG. 8  are located are provided with radiation protective enclosures such as concrete walls  44  to protect workers who might be in the vicinity. Where it becomes necessary to practically completely protectively enclose dangerous areas, the present invention is a very practical way to accomplish it. In doing so, the lower track  22  is laid out in the configuration required by the radiation source  42  and by the locations which the workers must be in to perform their task. Such a lay-out, once it is determined as to shape and length, can be done by bending a straight track,  22  and  24  to the desired curvature or by providing the tracks in sections which can be connected together by mechanical means or by welding. 
         [0039]    Likewise the most appropriate size and shape of wall mounting brackets such as  46  can be provided for clamping to wall  44  by screw clamps  48  ( FIG. 23 ). In this regard, once the lower track is set in position and leveled by leveling bolts  34  or the like, the upper track  24  is moved laterally to a vertical position over  22  by a screw mechanism (vertical adjustment means) generally designated  50  ( FIG. 20 ) and comprising a rod section  51  threaded into a tube section  52 , wherein  51  is connected to a vertical swivel joint  54  on the top of track  24 , and  52  is connected to a vertical swivel joint  56  on the bracket  46 . One of  51  or  52  is non-rotatable and longitudinally fixed in its swivel joint and the other is rotatable but also longitudinally fixed in its swivel joint to afford the pushing or pulling of the upper track to a vertical position by relative rotation between  51  and  52 . 
         [0040]    Referring to  FIGS. 16 and 17 , a variation of the vertical adjustment means is shown as comprising a threaded rod  58  rotatably mounted in a bushing  60  affixed to the top of wall  44  and longitudinally fixed therein by lock collars  62 . The rod is threaded through a bushing  64  affixed to the top of track  24 . Rotation of the bolt head  66  by e.g., a ratchet wrench, will push or pull the upper track to its proper verticality. A slotted arm  68  can be provided on the upper track and a complementary slotted arm  70  can be provided on wall  44  to firmly set the verticality of the upper track by tightening nut  72  on bolt  73 . 
         [0041]    Referring to  FIGS. 2 ,  3  and  19 , the stand alone embodiment generally designated  74  comprises the same upper track, panels and lower track as in, e.g.,  FIG. 1 , but does not require brackets or the like such as  46  for attaching the upper track to a structural portion of a building. 
         [0042]    In this embodiment of the present shield each side of the track base  23  is affixed to stabilizer arms  25  which are welded to the base or are affixed thereto by screws  27  or the like whereby the arms can be disassembled from the base. Opposing pairs of bracing  29  are affixed to arms  25  and to the upper track by welding or screws or the like, again to be able to disassemble the shield for easy transport thereof. Each foot portion  31  of arms  25  is provided with a leveling means such as bolt  33  threaded through the foot and adapted to firmly engage the floor and rigidly stabilize the shield assembly. 
         [0043]    In the placement of shield  74  wherein the shield sections are assembled, a preferred procedure for making it ready for use is to first level the lower track laterally and longitudinally by means of the leveling bolts  34  ( FIG. 14 ) or other leveling means such as to posture the panels in a vertical plane  47 . The leveling bolts  33  on the arms  25  are then adjusted in their screw sockets  35  to firmly engage the floor  32  and thus stabilize the entire shield assembly. 
         [0044]    Referring to  FIG. 25 , the caster housing  37  can be provided with a socket member  39  into which a steering rod  41  can be inserted and employed as a lever to rotate the caster housing and spindle  43  to steer the roller. 
         [0045]    Referring to the variation of  FIG. 7 , the guide rollers  55  are affixed to the tops  57  of the panels by an Allen type screw  59  passing through a thrust bearing  49  and having a shoulder  61  bearing on top  57  of the panel. 
         [0046]    In the variation of  FIG. 24  the upper rail  24  in configured as a vertical plate and the guide rollers  55  are mounted for vertical rotation in roller housings  53  affixed to the tops  57  of the panels. 
         [0047]    Referring to  FIG. 10 , a variation of the lower track roller mounting is shown where the spindle  43  is rotatably mounted through a bore  75  in a bushing  76 , and bears against a thrust bearing  77 . A sleeve member  78  welded at  79  to the bottom  63  of the panel threadedly receives bushing  76 . 
         [0048]    In the variation of  FIG. 11 , the spindle  43  is provided with an annular shoulder  80  for engaging thrust bearing  77 . Screws  82  threaded through the bottom  63  of the panel slidably nest in an annular groove  83  in the spindle for retaining it in bore  84  up into  63 . Sleeve bearing means  85  are preferably provided for the spindles. 
         [0049]    In  FIGS. 12 and 13  a latch  65  is shown for tightly drawing the panels together edgewise after they have been properly positioned. The latch comprises at threaded shaft  67  having an eye segment  69  through which a shaft member  71  is slidably mounted and fixed to bearing members  86  welded to an edge portion of each panel. A bushing member  87  is provided with a bore  88  for slidably receiving shaft  67 . A semi-sleeve member  89  is welded to an adjacent edge portion of each panel and is provided with a slot  90  for allowing pivoting of  67  around  71  and removal of bushing member  87  from  89 . A thumb nut  91  is provided for tensioning  67  sufficiently to retain said panels in edgewise contact. Additional such latches placed where desired on the panels may, of course, be used. 
         [0050]    The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications will be effected with the spirit and scope of the invention.