Abstract:
The invention places adequate and useable shielding in the path of the radiation that exists when nuclear workers perform maintenance and inspection of the Pressure Water Reactor Steam Generator component at a nuclear electric generating plant. The shielding has an upper and a lower track member that permit the two shield assembly halves to roll easily and be manipulated so that access and the associated work to be performed will result in significant reduction to the typical radiation dose that the nuclear workers receive during this work when compared with the current shielding approach. The shielding includes rollers that roll on track members that are located above and below the man-way opening.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation in part of U.S. patent application Ser. No. 11/772,669, filed Jul. 2, 2007, said application being based on Provisional Application No. 60/818,424, filed Jul. 2, 2006, both applications being by the same inventor and incorporated herein by reference. 
     
    
       [0002]    This invention relates to a biological radiation shield apparatus and more particularly to a track mounted, steam generator, man-way radiation shield apparatus that reduces the radiation exposure to the workers as they perform maintenance or inspection of a steam generator, especially the primary heat transfer system of a pressure water reactor (PWR) nuclear electric generating plant. 
       BACKGROUND OF THE INVENTION 
       [0003]    Routine maintenance or inspection requires the opening of certain ports in the Steam Generator system of a Pressure Water Reactor Nuclear Electric Generating Plant, thereby exposing the workers to significantly increased radiation levels. 
       FIELD OF THE INVENTION 
       [0004]    This invention relates to the field of apparatus typically defined as “shielding” against radiation in order to reduce the radiation levels and radiation exposure to the workers that are maintaining and/or inspecting Pressure Water Reactor (hereinafter “PWR”) Steam Generator systems. The invention provides an improved apparatus for and method of shielding (reducing the radiation levels through the physics principle of attenuation) while permitting the required maintenance or inspection. The improved shielding specifically addresses the elevated radiation levels that occur when the access ports, commonly called “man-ways”, are opened in order to perform this maintenance and/or inspection. 
         [0005]    Most reactors of this type have limited usable shielding. The main requirement that causes a limitation on the amount of shielding that can be utilized is due to the fact that the shielding has to be placed in a plane that is customarily offset approximately 25 degrees from vertical. 
         [0006]    Typically, a radiation shield apparatus is heavy so that a radiation shielding panel as a part thereof cannot be easily moved out of the way of the opening. Weight makes it a difficult item to move without having to overcome gravity. Yet, the shield apparatus must be heavy in order to reduce the radiation exposure to nuclear workers. Shield weight or mass in the path of the radiation is directly proportional to the effectiveness of the shielding. The prior art swing door shield system&#39;s shielding effectiveness is compromised by the weight that can be safely and easily be manipulated by the workers. 
         [0007]    The radiation shield apparatus must also provide adequate shielding while maintaining the necessary functional qualities to workers that are inspecting or maintaining the steam generator component of a pressure water nuclear electric generating plant. It is very desirable to increase the shielding by placing a significant weight or mass in the path of the radiation, while keeping maintenance or inspection accessible. Shielding must be maintained while accessing the port. 
         [0008]    The shielding must also be movable in a lateral or manipulated so as to remain between the worker and the radiation source while performing much of the work activity. Yet, again gravity limits the amount of shielding that can be utilized due to the shielding having to be placed in a plane that is customarily offset. Openings or radiation paths that occur with any shield that is hinged from one side and must be manipulated or swung open for access, have to be avoided. 
         [0009]    The worker cannot maintain the shield between him and the radiation source(s) and still be able to swing the shield out from in front of the man-way opening in order to have access for lines and hoses leading to robotics equipment for installing repair sleeves to eliminate leaking or failing tubes and other maintenance and inspection equipment. 
         [0010]    The existing shielding apparatus has a hinged shield that requires swinging out and away from the man-way port for access and therefore the workers are not able to “hide” behind the shield as they manipulate the maintenance and inspection equipment. Each opening and closing of the shield further exposes the worker to increased radiation levels due to the physical positions that the worker must assume in order to unlock, lock and manipulate this relatively heavy swinging shield door. 
         [0011]    By reference to  FIG. 2 ,  FIG. 3 ,  FIG. 4 , and  FIG. 5 , a structure of the prior art becomes clear. The man-way  102  has a typical shield  110  mounted thereover. The typical shield  110  includes a heavy hinge  112  supporting a swing door shield  114 . Due to tremendous weight of typical shield  110 , hinge  112  makes it difficult for swing door shield  114  to provide access for maintenance or repair of the reactor. 
         [0012]    In  FIG. 5 , it becomes clear that worker  124  must juggle a yellow lead blanket panel  120  and to use hoses  310  in order to perform maintenance on the reactor. Prior to doing anything, white lead blankets  122  must be placed around the man-way  102 . Thus, this cumbersome procedure indicates a great advantage for any system, which simplifies this procedure. 
         [0013]    Another object of the present invention is to address the demands of the Nuclear Regulatory Commission that requires all activities within the Radiological Controlled Area (RCA) be conducted with the goal that the radiation exposure to the nuclear workers be “as low as reasonably achievable” (ALARA).The worker cannot maintain the shield between him and the radiation source(s) and still be able to swing the shield out from in front of the man-way opening in order to have access for lines and hoses leading to robotics equipment for installing repair sleeves to eliminate leaking or failing tubes and other maintenance and inspection equipment. 
       SUMMARY OF THE INVENTION 
       [0014]    Among the many objectives of the present invention is the provision of a radiation shield apparatus with a track support frame on which at least one shielding assembly can be easily moved out of the way of the opening without having to overcome gravity. 
         [0015]    Another objective of the present invention is the provision of a radiation shield apparatus to reduce the radiation exposure to nuclear workers that will substantially overcome the deficiencies of the prior art devices. 
         [0016]    Yet another objective of the present invention is to provide adequate shielding while maintaining the necessary functional qualities to workers that are inspecting or maintaining the steam generator component of a pressure water nuclear electric generating plant. 
         [0017]    Still another objective of the present invention is to increase the shielding which means placing significant weight or mass in the path of the radiation. 
         [0018]    A further objective of the present invention is to be able to maintain the shielding effectiveness while accessing the man-way port. 
         [0019]    Yet a further objective of the present invention is the provision of an apparatus to permit the shielding to be moved laterally or manipulated so as to remain between the worker and the radiation source while performing much of the work activity. 
         [0020]    A still further objective of the present invention is to eliminate the effects of gravity that limit the amount of shielding that can be utilized due to the shielding having to be placed in a plane that is customarily offset. 
         [0021]    Another objective of the present invention is to eliminate the openings or radiation paths that occur with any shield that is hinged from one side and as a result must be manipulated or swung open for access. 
         [0022]    Yet another objective of the present invention is to permit the worker to maintain the shield between him and the radiation source(s) and still be able to swing the shield out from in front of the man-way opening in order to have access for lines and hoses leading to robotics equipment for installing repair sleeves to eliminate leaking or failing tubes and other maintenance and inspection equipment. 
         [0023]    Still another objective of the present invention is to address the demands of the Nuclear Regulatory Commission that requires all activities within the Radiological Controlled Area (hereinafter “RCA”) be conducted with the goal that the radiation exposure to the nuclear workers be “as low as reasonably achievable” (hereinafter “ALARA”). 
         [0024]    In addition, the actual installation process of the shielding material prior to any work or inspection is to be performed, must be considered as part of the total dose impact for the work to be performed and clearly a concern to the facility management and the Nuclear Regulatory Commission (hereinafter “NRC”). 
         [0025]    Therefore, being able to implement a track support frame by which the shielding is installed in a low dose area and then moved by means of or on a track support frame of this invention to move the shielding material into position for the maximum radiation dose impact for the work or inspection that is to be performed provides a great advantage. However, such a system is not in the prior art. 
         [0026]    It is intended that any other advantages and objects of the present invention that become apparent or obvious from the detailed description or illustrations contained herein are within the scope of the present invention. These and other objectives of the invention (which other objectives become clear by consideration of the specification, claims and drawings as a whole) are met by providing an apparatus for and method of shielding (reducing the radiation levels through the physics principle of attenuation) while permitting the required maintenance or inspection. The improved shielding specifically addresses the elevated radiation levels that occur when the man-ways are opened in order to perform maintenance or inspection. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0027]      FIG. 1  depicts a block diagram for the radiation shield apparatus  100  of this invention. 
           [0028]      FIG. 1  a depicts a second block diagram for the radiation shield apparatus  100  of this invention. 
           [0029]      FIG. 2  depicts a perspective view of the man-way  102  of the prior art. 
           [0030]      FIG. 3  depicts a perspective view of the cover plate  104  of the prior art. 
           [0031]      FIG. 4  depicts a front, top perspective view of swing door shield  114  of the prior art. 
           [0032]      FIG. 5  depicts a perspective view of worker  124  protected by yellow lead blanket panels  120  and white lead blankets  122  with the swing door shield  114  of the prior art. 
           [0033]      FIG. 6  depicts a perspective view of the radiation shield apparatus  100 . 
           [0034]      FIG. 7  depicts a perspective view of the track support frame  140 . 
           [0035]      FIG. 8  depicts a perspective view of top stud bolt assembly  148 . 
           [0036]      FIG. 9  depicts a perspective, top view of bottom stud bolt assembly  147 . 
           [0037]      FIG. 10  depicts a front, perspective view of radiation shield apparatus  100  in lock down configuration  179 . 
           [0038]      FIG. 11  depicts a front, perspective view of track roller stop  170 . 
           [0039]      FIG. 12  depicts a perspective view of roller  154  on track member  142 . 
           [0040]      FIG. 13  depicts an exploded view of hinge pin  200 . 
           [0041]      FIG. 14  depicts a perspective view of hinge pin  200  secured by pin clip  204 . 
           [0042]      FIG. 15  depicts a perspective view of right side-panel  212  being mounted in position. 
           [0043]      FIG. 16  depicts a side perspective view of right adjustable secondary lower shield panel  222 . 
           [0044]      FIG. 17  depicts a front, perspective view of radiation shield apparatus  100 . 
           [0045]      FIG. 18  depicts a front, perspective view of radiation shield apparatus  100 . 
           [0046]      FIG. 19  depicts a front, perspective view of the radiation shield apparatus  100 . 
           [0047]      FIG. 20  depicts a front, perspective view of the radiation shield apparatus  100 . 
           [0048]      FIG. 21  depicts a front, perspective view of the radiation shield apparatus  100 . 
           [0049]      FIG. 22  depicts a front, perspective view of the radiation shield apparatus  100 . 
           [0050]      FIG. 23  depicts a front, perspective view of the radiation shield apparatus  100 . 
           [0051]      FIG. 24  depicts a front, phantom view of radiation shield apparatus  100  showing port cover plug  252 , safety bars  251 , and HEPA port shield adapter  256 . 
           [0052]      FIG. 25  depicts a front, phantom view of radiation shield apparatus  100  showing port cover plug  252 , safety bars  251 , and HEPA port shield adapter  256 . 
           [0053]      FIG. 26  depicts a front view of original version  300  of radiation shield apparatus  100 . 
           [0054]      FIG. 27  depicts a profile cut-away view of original version  300 . 
           [0055]      FIG. 28  depicts a profile cut-away view of original version  300 . 
           [0056]    Throughout the figures of the drawings, where the same part appears in more than one figure of the drawings, the same number is applied thereto. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0057]    The invention provides an improved apparatus for and method of shielding (reducing the radiation levels through the physics principle of attenuation) while permitting the required maintenance or inspection. The improved shielding specifically addresses the elevated radiation levels that occur when the man-ways are opened in order to perform this maintenance and/or inspection. Moreover, it pertains specifically to an improved shield door system used as a radiation shield apparatus that includes a track system on which a radiation shielding panel or panels can be easily moved out of the way of the opening without having to overcome gravity. The shielding provided by the shield door system has two half shield panels closing the man-way; and that, when moved, can provide partial or full access to the man-way port. Each of the shield panels includes a hinged lower section that can be opened as needed to permit insertion of inspection devices, including robotics and other equipment for the repair and/or inspection of the internals of the Steam Generator. This rolling shield system easily moves (rolls) across the face of the open port on rollers and permits the worker to manipulate the maintenance and/or inspection equipment as needed and still remain completely or partially behind the protective radiation shield. 
         [0058]    In view of the limitations now present in the prior art, the present invention provides a new and useful radiation shielding apparatus which reduces the radiation dose received by the workers that are maintaining or inspecting PWR Steam Generator system. The improved shielding specifically addresses the elevated radiation levels that occur when the man-ways, are opened in order to perform this maintenance and/or inspection. 
         [0059]    The invention significantly decreases the radiation dose that the workers receive during all phases of work performed in the area of the man-way port. In addition, the effective shielding of the prior art system when fully installed is approximately one-third that of the present invention due to the fact that the face of the port is inclined downward by approximately 25 degrees and the existing shielding must overcome gravity in order to swing the door up and into position. 
         [0060]    Even though the invention includes the use of a single door or shield panel assembly that will move laterally on a track member, this description will detail the invention utilizing two doors or shield panel halves, a right half and a left half. The use of a double shield door or panel minimizes the amount of weight of any single component that must be handled by an individual nuclear worker. 
         [0061]    Each shielded door panel half of the shield door system has three parts, an upper primary shield panel that includes the rollers, a secondary lower shield panel that is hinged off of the primary shield panel and a side shield that also is attached to the angle steel on the primary shield panel. The assembled shielded door panel weighs significantly more than what can be easily handled and as described above must be assembled in place from three lighter weight component shield panel pieces. All of the shield panels have at least 2.5 centimeters (one inch) thick lead sheet or shielding equivalent to that of 2.5 centimeters (one inch) of lead and are contained in a metal covering such as stainless steel sheeting. 
         [0062]    The goal is to improve the shielding quality of the shield which requires placing mass in the path of the radiation. The shield panel halves roll on an upper track that supports the weight and a lower track that maintains the shield at an angle from vertical and in close proximity to the plane of the man-way opening. The track and supporting frame is attached to the sealing surface that is around the man-way opening in the same location the approximately 10.2 centimeters (four inches) thick steel cover that has to be removed from the opening in order to perform the required maintenance and/or inspection. Four of the approximately 20 available stud apertures are used to secure the track support frame to the surface around the man-way opening. 
         [0063]    The man-way opening is tipped downward by approximately 25 degrees. The current system utilizes a hinged shield that swings to one side only. The process of opening requires that gravity must be overcome because of the downward tipping and when the shield is swung away from the opening the workers in the area receive a significant amount of radiation exposure. As stated previously, the amount of shielding is compromised in order to keep the weight at a manageable level. 
         [0064]    The invention includes two rollers at the top of each half shield assembly that permits easy rolling, even with the necessary weight, on a track which is supported above the man-way opening. A single roller is located at the bottom corner of each shield halves and roll on the underside of the lower track member. All of the weight of each shield assembly halves is carried by the upper track and the two rollers. The lower roller and track simply maintains the shield halves at the approximately 25 degree angle and in close proximity to the face of the man-way opening. 
         [0065]    The invention places the shielding halves on a level plain and therefore the amount of weight of the shielding does not impact the ability of a worker to move the shielding as needed for access. The invention reduces the radiation levels directly in front of the shield by a factor of approximately three (3) compared to the existing shielding due directly to the amount of mass in the path of the radiation. In addition, the shielding maybe moved in such as way that access to the man-way opening can often be accomplish while the worker remains behind one of the halves, this benefit cannot be accomplished with the swing door type shielding currently used. 
         [0066]    Adding  FIG. 1  to the consideration, the structure of radiation shield apparatus  100  can clearly be seen. Radiation shield apparatus  100  covers man-way  102 . Radiation shield apparatus  100  has a track support frame  140  (also referred to as a track system) onto which attaches a left half shield assembly  230  (also referred to as a left shield panel, a radiation shielding panel, or a left shield panel assembly) and a right half shield assembly (also referred to as a right shield panel, a radiation shielding panel, or right shield panel assembly)  232  which move across the man-way  102  of the steam generator. Left half shield assembly  230  and right half shield assembly  232  cooperate to open or close man-way  102  as desired. 
         [0067]    Left half shield assembly  230  has a left adjustable secondary lower shield panel  220  (also referred to as the left lower hinged panel) which can be in the open adjustment  240  or the closed adjustment  242 . Right half shield assembly  232  has a right adjustable secondary lower shield panel  222  (also referred to as the right lower hinged panel) which can be in the open adjustment  240  or the closed adjustment  242 . Open adjustment  240  provides access for maintenance hoses  310  and other equipment to be used by worker  124  for maintenance or repair. 
         [0068]    Adding  FIG. 1   a  to the consideration, a variation to radiation shield apparatus  100  can be clearly seen. In this embodiment, radiation shield apparatus  100  has a single shield assembly  228  which has a single adjustable secondary lower shield panel  219 . The structure and function of this embodiment are otherwise the same as that described in  FIG. 1 . 
         [0069]    Adding  FIG. 2 ,  FIG. 3 ,  FIG. 4 , and  FIG. 5  to the consideration, the problems and safety concerns of the prior art can be clearly seen. In the prior art, cover plate  104  is removed from man-way  102  and a typical shield  110  is installed. Typical shield  110  is attached to sealing surface  106  in much the same manner as seen in  FIG. 7 ,  FIG. 15 ,  FIG. 16 , and  FIG. 17 . 
         [0070]    Typical shield  110  has swing door shield  114 . Swing door shield  114  is able to swing open through its interaction with hinge  112 . Swing door shield  114  swings out and away from man-way  102 . 
         [0071]    However, swing door shield  114  does not provide adequate protection to workers  124  as discussed in the background of the invention. Thus, to prevent harmful exposure emanating from man-way  102  yellow lead blanket panels  120  and white lead blankets  122  are necessary. 
         [0072]    Adding  FIG. 6  to the consideration, the structure of radiation shield apparatus  100  which covers man-way  102  becomes clear. The man-way  102  is inclined up to 35 degrees from vertical, with the top portion  130  being outward by that amount relative to bottom portion  132 . More preferably, the incline is about 10 degrees to 30 degrees. Most preferably, the incline is 20 degrees to 30 degrees. 
         [0073]    Radiation shield apparatus  100  has a left half shield assembly  230  and a right half shield assembly  232 . Left half shield assembly  230  and right half shield assembly  232  are attached to track support frame  140  through top support roller assembly  150  and bottom guide roller assembly  152 . 
         [0074]    Maintenance hoses  310  can be inserted through radiation shield apparatus  100  once it is installed over man-way  102 . Maintenance hoses  310  are utilized to clean and perform routine maintenance. 
         [0075]    Adding  FIG. 7 ,  FIG. 8 , and  FIG. 9  to the consideration, the structure of track support frame  140  becomes clear. Track support frame  140  is substantially rectangular in shape and has top cross member  160  which is oppositely disposed from bottom cross member  162 . Left standing member  164  and right standing member  166  are oppositely disposed from each other and join top cross member  160  and bottom cross member  162 . Track support frame  140  mounts over man-way  102  and attaches to sealing surface  106 . Track support frame  140  is secured to sealing surface  106  through stud bolts  144 . 
         [0076]    Once cover plate  104  is removed from man-way  102 , stud bolts  144  are securely inserted into stud apertures  108  on sealing surface  106 . Track support frame  140  has top cross member  160  which has alignment slots  101 . Alignment slots  101  insert over stud bolts  144  to guide the correct and precise positioning of track support frame  140 . Once track support frame  140  is correctly positioned, stud bolts  144  are tightened in top cross member  160 . Stud bolts  144  are also inserted into bottom apertures  163  and tightened into bottom cross member  162 . 
         [0077]    Top stud bolt assembly  148  has top cross member  160  and track member  142 . Top cross member  160  has track member  142  at a perpendicular plane to man-way  102 . Track member  142  has track roller stop  170  on each side to ensure that radiation shield apparatus  100  does not roll over the end of top cross member  160 . Upper track member also has push pull center stop lock  180 . 
         [0078]    Bottom stud bolt assembly  147  had bottom cross member  162  and track member  142  at a perpendicular plane to man-way  102 . Bottom cross member  162  has bottom apertures  163  and stud bolts  144 . Stud bolts  144  are permanently affixed to bottom cross member  162  through bolt tethers  146 . 
         [0079]    Now adding  FIG. 10  to the consideration, the lock down configuration  179  of radiation shield apparatus  100  can clearly be seen. Lock down configuration  179  creates a lockable high radiation area, which is defined by the Nuclear Regulatory Commission as a high radiation area which is controlled through a locking system. 
         [0080]    To establish the lock down configuration  179 , left half shield assembly  230  and right half shield assembly  232  are separated and push pull center stop lock  180  is moved from backward position and placed forward (also depicted in  FIG. 27  and  FIG. 28 ). Then, left half shield assembly  230  and right half shield assembly  232  are pushed together. Push pull center stop lock  180  has two cavities to accommodate the upper portion of left half shield assembly  230  and right half shield assembly  232 . Push pull center stop lock  180  stops the movement of left half shield assembly  230  and right half shield assembly  232  toward each other. 
         [0081]    Center draw latch  182  (depicted in  FIG. 17 ) has latch lock slot  172 . Lockable slide bolts  224  each have slide bolt lock slots  174 . Cable  178  threads through latch lock slot  172  and slide bolt lock slots  174  and the ends of cable  178  are securely locked together with pad lock  176 . 
         [0082]    The workings of push pull center stop lock  180  and cable  178  with pad lock  176  establish lock down configuration  179 . Push pull center stop lock  180  prevents either left half shield assembly  230  or right half shield assembly  232  from being moved past the substantially center point on upper track  142  where push pull center stop lock  180  is located. Center draw latch  182 , cable  178 , and pad lock  176  prevent right half shield assembly  232 , left half shield assembly  230  from being opened or moving away from the center toward the left and right ends of upper track support bar  142 . Also, cable  178  and pad lock  176  prevent either left adjustable secondary lower shield panel  220  or right adjustable secondary lower shield panel  222  from being adjusted and thus exposing man-way  102 . 
         [0083]    Now adding  FIG. 11  and  FIG. 12  to the consideration, top support roller assembly  150  and bottom guide roller assembly  152  can be clearly seen. Only top support roller assembly  150  is depicted in these figures but bottom guide roller assembly  152  functions in the same manner. Top support roller assembly  150  has two rollers  154  and track member  142 . Bottom guide roller assembly  152  has track member  142  and a single roller  154 . 
         [0084]    Left half shield assembly  230  and right half shield assembly  232  travel, by means of or on upper and lower rollers  154 , on upper and lower track members  142 . For the lower track member  142 , a single roller  154  is attached to angle steel  194  (depicted in  FIG. 13 ,  FIG. 14 , and  FIG. 15 ) by roller bolt  156 . While a pair of rollers  154  is attached to each the upper portion of left half shield assembly  230  or right half shield assembly  232  by roller bolt  156  in top support roller assembly  150 . 
         [0085]    Upper track member  142  and lower track member  142  are held perpendicular to man-way  102 . The upper portion of left primary shield panel  184  and right primary shield panel  186  are angled about upper track member  142  to allow for this perpendicular alignment. Angle steel  194  is also angled about lower track member  142  to allow for this perpendicular alignment. 
         [0086]    Top support roller assembly  150  is designed to support the weight of left half shield assembly  230  and right half shield assembly  232 . Bottom guide roller assembly  152  is designed to guide and support the workings of top support roller assembly  150 , especially at the desired angle thereby facilitating movement and use of radiation shield apparatus  100 . Since the movement of left half shield assembly  230  and right half shield assembly  232  are not offset, the effects of gravity are not as great and thus, it is easier to move heavier shielding. 
         [0087]    Now adding  FIG. 13  and  FIG. 14  to the consideration, the connection between right primary shield panel  186  and right adjustable secondary lower shield panel  222  can be clearly seen. While only the right side is depicted, the left primary shield panel  184  and the left adjustable secondary lower shield panel  220  function in the same manner. 
         [0088]    Right adjustable secondary lower shield panel  222  has hinge sleeve  206  which cooperates with dove tail cavity  196  on right primary shield panel  186 . Right primary shield panel  186  is welded or otherwise suitably attached to angle steel  194 . Hinge sleeve  206  is aligned with hinge end aperture  208  and hinge pin  200  is slid through hinge sleeve  206  and hinge end aperture  208  on angle steel  194  to connect the right adjustable secondary lower shield panel  222  and right primary shield panel  186 . 
         [0089]    Hinge pin  200  is secured in hinge sleeve  206  through different mechanisms on each end. Dove tail connector  198  cooperates with dove tail cavity  196  to form a secure and stable attachment. Dove tail connector  198  is designed to precisely fit in dove tail cavity  196 . 
         [0090]    On the other end, hinge pin  200  is secured through the interaction of pin aperture  202  and pin clip  204 . Pin clip  204  inserts into pin aperture  202  to prevent hinge pin  200  from sliding horizontally in hinge sleeve  206 . Pin tether  201  permanently attaches pin clip  204  to right adjustable secondary lower shield panel  222 . 
         [0091]    Now adding  FIG. 15  to the consideration, the interaction of angle steel  194  and right side-panel  212  can be clearly seen. While only right side-panel  212  is depicted, left side-panel  210  attaches in the same fashion. Angle steel  194  is attached to right primary shield panel  186  through welding or any other suitable attachment mechanism. Angle steel  194  has upper key slot  216  and lower key slot  218 . 
         [0092]    On right side-panel  212 , are a pair of carriage-type bolt heads  214 . Carriage-type bolt heads  214  are designed to cooperate with upper key slot  216  and lower key slot  218  to form a secure and releaseable connection between right side-panel  212  and angle steel  194 . 
         [0093]    Now adding  FIG. 16  to the consideration, the adjustability of secondary lower shield panels  220  and  222  can clearly be seen. Left adjustable secondary lower shield panel  220  and right adjustable secondary lower shield panel  222  can be adjusted at a variety of angles in relation to left primary shield panel  184  and right primary shield panel  186 . 
         [0094]    A depiction of right adjustable secondary lower shield panel  222  is depicted in this figure but left adjustable secondary lower shield panel  220  functions in the same manner. Latch adjustment plate  188  is attached to angle steel  194  (as depicted in  FIG. 13 ). Latch adjustment plate  188  can be welded to angle steel  194  or attached in any other suitable fashion. Lockable slide bolt  224  is attached to right adjustable secondary lower shield panel  222  through any suitable attachment mechanism. Latch adjustment plate  188  has a series of latch apertures  190 . 
         [0095]    The user positions right adjustable secondary lower shield panel  222  at a desired angle relative to right primary shield panel  186 . Then, lockable slide bolt  224  and a desired latch aperture  190  are aligned and lockable slide bolt  224  cooperates to secure the connection. When the angle of right adjustable secondary lower shield panel  222  needs to be changed, lockable slide bolt  224  is removed. 
         [0096]    Adding  FIG. 17  to the consideration, the structure of radiation shield apparatus  100  becomes more clear. As previously stated ( FIG. 7 ), radiation shield apparatus  100  is mounted on sealing surface  106  through the interaction with track support frame  140 . Left half shield assembly  230  and right half shield assembly  232  are mounted in three pieces so that each half can provide additional protection (as described in the background of the invention). First, left primary shield panel  184  and right primary shield panel  186  are mounted on upper track member  142 . Then, left side-panel  210  is attached to left angle steel  194  and right side-panel  212  is attached to right angle steel  194  (as depicted in  FIG. 15 ) and left adjustable secondary lower shield panel  220  is attached to left primary shield panel  184  and right adjustable secondary lower shield panel  222  is attached to right primary shield panel  186  (as depicted in  FIG. 13  and  FIG. 14 ). 
         [0097]    Attaching the three pieces of left half shield assembly  230  and right half shield assembly  232  in this manner provides benefits. First, the entirety of left half shield assembly  230  or right half shield assembly  232  can have greater weight, since each individual piece (primary shield panel  184  or  186 , adjustable secondary lower shield panel  220  or  222 , or side-panel  210  or  212 ) can have greater weight. The worker only has to lift one individual piece at a time so each individual piece can be composed of thicker lead thus adding to additional shielding. 
         [0098]    Secondly, the pieces can be installed at the outer edges of upper track member  142  and lower track member  142  so that the worker can install the pieces away from the man-way and the radiation exposure. Once, the left half shield assembly  230  and the right half shield assembly  232  are installed they can be rolled along upper track member  142  and lower track member  142  to cover man-way  102  and the worker can be shielded from the radiation from behind left half shield assembly  230  or right half shield assembly  232 . 
         [0099]    Left half shield assembly  230  and right half shield assembly  232  slide along track member  142  in either direction until their movement is stopped by the opposing half, push pull center stop lock  180  (as depicted in  FIG. 11 ), or a track roller stop  170 . On lower track member  142  is release clip  158  which further prevents left half shield assembly  230  or right half shield assembly  232  from sliding off of track member  142 . Release clips  158  also function to guide and support shield assembly halves  230  and  232  in case a worker  124  (as depicted in  FIG. 1 ) applies too much force in sliding either along track member  142 . 
         [0100]    Release clips help to ensure that either right half shield assembly  232  or left half shield assembly  230  maintain their secure and stable position in track member  142 . 
         [0101]    Left adjustable secondary lower shield panel  220  and right adjustable secondary lower shield panel  222  are secured in the desired angle through their interactions with lockable slide bolt  224  and latch apertures  190  on latch adjustment plate  188  (as described in detail in  FIG. 16 ). 
         [0102]    Right half shield assembly  232  and left half shield assembly  230  can be securely but releaseably locked together through center draw latch  182 . Center draw latch  182  pulls right half shield assembly  232  and left half shield assembly  230  together and locks them in place. 
         [0103]    Left primary shield panel  184  has high efficiency particulate arrestance (hereinafter “HEPA”) port opening  250 . As shown in  FIG. 17 , port cover plug  252  covers HEPA port opening  250 . Port cover plug  252  is securely but releaseably held in place through cover plug securing bolt  254 . 
         [0104]    Adding  FIG. 18 ,  FIG. 19 ,  FIG. 20 ,  FIG. 21 ,  FIG. 22 , and  FIG. 23  to the consideration, the flexibility of radiation shield apparatus  100  is seen through the adjustability of secondary lower shield panels  220  and  222  and left half shield assembly  230  and right half shield assembly  232 . As depicted in  FIG. 11  and  FIG. 12 , left half shield assembly  230  and right half shield assembly  232  move through top support roller assembly  150  and bottom guide roller assembly  152 . As depicted in  FIG. 13  and  FIG. 16 , left adjustable secondary lower shield panel  220  and right adjustable secondary shield panel  222  rotate through its interactions hinge pin  200  and hinge sleeve  206  with and lock through its interactions with latch adjustment plate  188 , latch apertures  190 , and lockable slide bolt  224 . 
         [0105]    Referring specifically to  FIG. 18 ,  FIG. 19 , and  FIG. 20 , the left half shield assembly  230  and right half shield assembly  232  can be moved into a variety of positions relative to each other. In  FIG. 18 , left half shield assembly  230  is open  244  exposing man-way  102  while right half shield assembly  232  is closed  246  covering man-way  102 . Left primary shield panel  184  travels with left half shield assembly  230  as right primary shield panel  186  remains in place with right half shield assembly  232 . Left adjustable secondary lower shield panel  220  is in open adjustment  240  while right adjustable secondary lower shield panel  222  is in closed adjustment  242 . 
         [0106]    Because left primary shield panel  184  travels with left half shield assembly  230  as right primary shield panel  186  remains in place with right half shield assembly  232 , a half slideability is produced. Left primary shield panel  184  may travel independently of right half shield assembly  232 . Thus, access is provided to the nuclear reactor  128  for repair or maintenance. 
         [0107]    In  FIG. 19 , both left half shield assembly  230  and right half shield assembly  232  are open  244 , fully exposing man-way  102 . Left primary shield panel  184  travels with left half shield assembly  230  and right primary shield panel  186  travels with right half shield assembly  232 . Left adjustable secondary lower shield panel  220  is in open adjustment  240  while right adjustable secondary lower shield panel  222  is in closed adjustment  242 . 
         [0108]    In  FIG. 20 ,  FIG. 21 ,  FIG. 22 , and  FIG. 23 , both left half shield assembly  230  and right half shield assembly  232  are closed  246  fully covering man-way  102 . Left primary shield panel  184  remains in place with left half shield assembly  230  while right primary shield panel  186  remains in place with right half shield assembly  232 . 
         [0109]    Referring specifically to  FIG. 20 ,  FIG. 21 ,  FIG. 22 , and  FIG. 23 , the adjustability of left adjustable secondary lower shield panel  220  and right adjustable secondary lower shield panel  222  can be clearly seen. These panels can be individually or jointly opened or closed through their adjustable interactions as seen in  FIG. 13 , and  FIG. 16 . 
         [0110]    In  FIG. 20  left adjustable secondary lower shield panel  220  is in open adjustment  240  while right adjustable secondary lower shield panel  222  is in closed adjustment  242 . In  FIG. 21 , both right adjustable secondary lower shield panel  222  and left adjustable secondary lower shield panel  220  are in open adjustment  240 . In  FIG. 22 , left adjustable secondary lower shield panel  220  is in closed adjustment  242  while right adjustable secondary lower shield panel  222  is in open adjustment  240 . In  FIG. 23 , both left adjustable secondary lower shield panel  220  and right adjustable secondary lower shield panel  222  are in closed adjustment  242 . 
         [0111]    Open adjustment  240  permits limited access to man-way  102 . This limited access permits the worker to manipulate maintenance and/or inspection equipment to access man-way  102  (as depicted in  FIG. 6 ) and still remain completely or partially behind the protective radiation shield. Adjustable secondary lower shield panels  220  and  222  direct the escaping radiation downward while left side-panel  210  and right side-panel  212  block radiation from escaping from the sides. This combination of limited access, guiding, and blocking significantly reduces the amount of radiation exposure to worker (as depicted in  FIG. 1 ). 
         [0112]    Left side-panel  210  and right side-panel  212  may end up as installed in the pieces. Assembling by pieces greatly facilitates the installation of the radiation shield apparatus  100 . The combination for the left-side panel  210  and right side panel  212  forms radiation shield apparatus  100 . 
         [0113]    Now adding  FIG. 24  and  FIG. 25  to the consideration and also considering  FIG. 17 , various features of radiation shield apparatus  100  can be clearly seen. In  FIG. 24 , left primary shield panel  184  has HEPA port opening  250  and safety bars  251 . HEPA port opening  250  allows radiation and harmful matter to be released from man-way  102 . While, safety bars  251  ensure that worker  124  (as depicted in  FIG. 1 ) does not place his hands in the HEPA port opening  250 . 
         [0114]    In  FIG. 25 , left primary shield panel  184  has HEPA port shield adapter  256  and flexible ducting  262 . These structures are useful in drawing off dangerous radiation while allowing accessibility to the man-way  102 . Once radiation passes through HEPA port shield adapter  256  and flexible ducting  262 , it safely vents to the environment. HEPA port shield adapter  256  is attached to left primary shield panel  184  through cover plug securing bolt  254 . 
         [0115]    Now adding  FIG. 26 ,  FIG. 27 , and  FIG. 28  to the consideration, the original version  300  of radiation shield door system can be seen. The major modifications between the present radiation shield apparatus  100  and the original version  300  are latch apertures  190  and right side-panel  212  and left side-panel  210 . Latch apertures  190  provide adjustability for adjustable secondary lower shield panels  220  and  222 . 
         [0116]    First, latch apertures  190  are replaced with outside latch apertures  304 . In the embodiment depicted in  FIG. 26 ,  FIG. 27 , and  FIG. 28 , outside latch apertures  304  appear in the form of tubes, that are secured to the outer perimeter of right side-panel  212  and left-side panel  210 . Whereas in radiation shield apparatus  100 , latch apertures  190  are holes that are bored into or otherwise formed in the outer rim of latch adjustment plate  188  (as depicted in  FIG. 13  and  FIG. 16 ). 
         [0117]    Second, upper key slot  216  and lower key slot  218  are replaced with side mounts  302 . In radiation shield apparatus  100 , upper key slot  216  and lower key slot  218  are located on the back of right side-panel  212  and left side-panel  210 . Where as in the original version  300 , the side mounts are located on the inner side of right side-panel  212  and left side-panel  210 . The inner side is the side that faces left adjustable secondary lower shield panel  220  or right adjustable  20  secondary lower shield panel  222  once right side-panel  212  and left side-panel  210  are in place. The back mounting of upper key slot  216  and lower key slot  218  makes the left side-panel  210  and right side-panel  212  more flexible in that either left side-panel  210  and right side-panel  212  can be inserted into either side of radiation shield apparatus  100 . 
         [0118]    This application—taken as a whole with the abstract, specification, claims, and drawings—provides sufficient information for a person having ordinary skill in the art to practice the invention disclosed and claimed herein. Any measures necessary to practice this invention are well within the skill of a person having ordinary skill in this art after that person has made a careful study of this disclosure. 
         [0119]    Because of this disclosure and solely because of this disclosure, modification of this tool can become clear to a person having ordinary skill in this particular art. Such modifications are clearly covered by this disclosure.