Abstract:
An apparatus and method are provided for inverting the lower internal assembly of a nuclear reactor. The apparatus includes a frame which is sized to receive the lower internal assembly. The frame supports the lower internal assembly as it is being inverted. The apparatus also includes a spider assembly which fits within the lower internal assembly and provides support for a baffle assembly located therein. The method includes the steps of removing the lower internal assembly from a reactor vessel and rotating the lower internal assembly prior to performing maintenance.

Description:
This Application claims the benefit of U.S. Provisional Application Ser. No. 60/155,976, filed Sep. 24, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a method and apparatus to aid in the maintenance and repair of the lower internal assembly of a nuclear reactor vessel, and more specifically, to a method and apparatus which provides a frame capable of inverting the lower internal assembly so that repair and maintenance operations may be performed with greater speed, thus reducing the exposure of workers to radiation. 
     2. Background Information 
     Because of the radiation hazard present while performing repair and maintenance operations on the components of a nuclear reactor, it is desirable to limit the exposure of workers to any radioactive components during such maintenance and repair procedures. A nuclear reactor includes a stationary reactor vessel which encloses a removable reactor core assembly. The reactor core assembly includes two main assemblies, the upper internal assembly and the lower internal assembly. For example, the upper internal assembly includes the control rod drive mechanisms, control rod drive shafts and the upper core plate. The lower internal assembly includes the core barrel, lower instrumentation guide tubes, tie plates and a baffle. The nuclear fuel assemblies or fuel cells are maintained within the core barrel between the upper core plate and the lower core plate. 
     It is known in the prior art to perform maintenance operation on the lower internal assembly. Access to the lower internal assembly is gained by removing the reactor vessel upper head assembly and the upper internal assembly, including the upper core plate. This procedure exposes the fuel assemblies which are also removed. Once the upper internal assembly, which includes the upper core plate, and fuel assemblies have been removed, the lower internal assembly may be removed from the reactor vessel. When removed from the reactor vessel, the lower internal assembly is set on a storage stand which supports the lower internal assembly above the maintenance bay floor. While on the maintenance stand the lower end of the core barrel is approximately thirty feet under water. 
     Typically, the only procedure performed on the lower internal assembly is the inspection of the weld between the lower core forging and the core barrel. Should maintenance be required on elements of the lower internal assembly below the lower core forging, it would be necessary to construct a tool capable of being submerged thirty feet and turned at a 90-degree angle in order to access the lower internal assembly. Maintenance on the lower face of the lower core forging would require the instrument to have an additional 90-degree turn to access the lower side of the lower core forging. Maintenance procedures using such a tool would be time consuming and would expose workers to radiation throughout the period in which the tool was used. Such a high level exposure to radiation is not desirable. 
     Therefore, there is a need for a method and apparatus to allow workers to repair the lower internal assembly of a nuclear reactor core assembly which would reduce the amount of exposure to radiation. 
     SUMMARY OF THE INVENTION 
     These needs and others are satisfied by the invention which is directed to a method and apparatus for up-ending the lower internal assembly of a nuclear reactor so that the lower internal assembly and lower core forging may be directly accessed by maintenance and repair workers. 
     The apparatus for up-ending the core barrel and lower internal assembly includes a support which is capable of supporting the core barrel and lower internal assembly in the upright orientation, the horizontal orientation, and the inverted orientation. The apparatus includes a frame assembly having support brackets and support saddles for the core barrel. The apparatus further includes a spider assembly which is fitted within the core barrel and is used to support the internal baffle while the barrel is in the horizontal orientation. The apparatus allows workers to invert the lower internal assembly so that the lower core forging is positioned above the core barrel. 
     This invention further provides the method for inverting the lower internal assembly. The lower internal assembly is removed from the reactor vessel and placed on the storage stands as is known in the prior art. The spider assembly, which supports the baffle located within the core barrel, is then inserted in the lower internal assembly. The lower internal assembly may be lifted and inserted into the frame. Once the lower internal assembly is positioned within the frame, the frame is rotated ninety degrees before being inverted. Once the lower internal assembly is in the inverted orientation, the lower internal assembly is removed from the frame and positioned on the storage stand in the inverted position. Any maintenance on the lower face of the core forging or structures typically located below the lower core forging can now be performed with tools that directly access the lower internal assembly and lower core forging without the necessity of having such tools bent 90 degrees or more. Accordingly, maintenance and repair procedures can be performed more quickly with a reduced radiation exposure to the workers. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A full understanding of the invention can be gained from the following description of the preferred embodiment when read in conjunction with the accompanying drawings in which: 
     FIG. 1 is a partial cross sectional side elevational view of a nuclear reactor containment building. 
     FIG. 2 is a cross sectional side elevational view of a nuclear reactor vessel. 
     FIG. 3 is a cut-away perspective view of the lower internal assembly. 
     FIG. 4 is a top view of the lower internal assembly. 
     FIG. 5 is a top view of a spider assembly baffle support plate assembly. 
     FIGS. 6A-6C are views of a spider plunger assembly, more specifically; FIG. 6A is a top view of a plunger assembly, FIG. 6B is a side view of a plunger assembly, and FIG. 6C is a top view of an alternate plunger head contour. 
     FIGS. 7A-7E are side elevational views of the spider assembly installed in the lower internal assembly. More specifically, FIG. 7A is a side elevational view of the spider assembly with one baffle support plate assembly in place, FIG. 7B is a side view with two baffle support plate assemblies in place, FIG. 7C is a side view with three baffle support plate assemblies in place, FIG. 7D is a side view showing the complete spider assembly, and FIG. 7E is a detail of a support column foot. 
     FIGS. 8A-8C are views of the lifting plate. More specifically, FIG. 8A is a top view of the lifting plate assembly, FIG. 8B is a view showing the lifting coupling in the upright orientation, and FIG. 8C is a view of the lifting coupling in the inverted orientation. 
     FIGS. 9A-9D are views of the frame. More specifically, FIG. 9A is a side elevational view of the frame, FIG. 9B is a cut-away front elevational view of the frame, FIG. 9C is a top view of the frame with the lifting plate assembly in place, FIG. 9D is a bottom view of the frame. 
     FIG. 10 is a side elevational view of the lower internal structure adjacent to the frame. 
     FIGS. 11A through 11H are schematic views of the up-ending procedure. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows nuclear reactor containment building  10 . The containment building  10  includes a floor  12 , a plurality of walls  14  made from shielded concrete. The floor  12  is submerged under water  16  containing boric acid. The floor  12 , includes a reactor vessel pit  20 , and a maintenance bay  40 . Both the reactor vessel pit  20  and the maintenance bay  40  are under water  16 . The reactor vessel pit  20  has a generally cylindrical side wall  22  and a bottom surface  24 . The side wall  22  includes a support means  26  to support a reactor vessel  100  (described below). Maintenance bay  40  includes work stands  42 ,  44 . Maintenance bay  40  may have a floor  41  which is at a lower level than floor  12 . Containment building  10  also includes a moveable polar crane  70  above water level  16 . Polar crane  70  is moveable between a position above the reactor vessel pit  20  and the maintenance bay  40 . 
     Typically, a reactor vessel  100  is disposed within the reactor vessel pit  20 . As shown on FIG. 2, the reactor vessel  100  is cylindrical with a hemispherical bottom head  102 , a cylindrical body  104 , and a flanged removable upper head  106 . A plurality of control rod drive mechanisms  107  are mounted on upper head  106 . The drive mechanisms  107  are each coupled to a control rod drive shaft  108  which passes through openings  103  in upper head  106 . Each control rod drive shaft supports a control rod cluster  109  which may be inserted or removed from the reactor core  220  (described below). The reactor pit bottom surface  24  may include hollow columns  200  which allow instrumentation  204  to pass therethrough. The reactor vessel body  104  has at least two openings  110 ,  112  which allow inlet nozzle  133  and outlet nozzle  134  (shown on FIG. 3) to pass therethrough. The reactor vessel  100  is supported by the support means  26  located in the reactor vessel pit  20 . The support means  26  may include a ledge on the lower surface of openings  110 ,  112 . Within the reactor vessel  100  is an upper internal assembly  120  and a lower internal assembly  170 . The upper portion of the reactor vessel  100  forms a support ledge  101  which partially supports the upper and lower internal assemblies  120 ,  170 . 
     The upper internal assembly  120  includes the top support plate  122 , support columns  124 , control rod guide tubes  126  and the upper core plate  128 . The principal function of these structures are to align and locate the upper end of the fuel assemblies  222  (described below), and protect and guide control rod clusters  109  as they are inserted and removed from the reactor core  220 . 
     Upper support plate  122  is generally cylindrical having a plurality of openings therethrough  123 . A plurality of lower control rod guide tubes  142  are aligned with a portion of the plurality of openings  123  through the upper support plate  122 . These lower guide tubes  142  are further aligned with the control rod drive shaft openings  103  passing through the upper head  106 . Upper core plate  128  is generally cylindrical having a plurality of openings  129  therethrough. A portion of these openings  129  are aligned with the openings  123  in the upper support plate  122  and allow control rod clusters  109  to be inserted and removed from the reactor core  220 . Other openings  129  allow water to pass through the upper core plate  128 . 
     As shown in FIGS. 2 and 3, the lower internal assembly  170  includes the core barrel  172 , a baffle assembly  171  (shown in FIG.  3 ), the lower core plate  176 , the core support forging  179 , a tie plate assembly  180 , energy absorbers  194  and a secondary core support  196 . The core barrel  172  has an upper end  182  and a lower end  184 . As shown in FIG. 2, the core barrel  172  includes one or more outlet ports  132  (only one outlet port is shown) which are each coupled to an outlet nozzle  134 . Outlet nozzle  134  is in fluid communication with outlet pipe  135  which communicates with a steam generating vessel (not shown). The upper end  182  of the core barrel  172  includes a flange  173  extending perpendicularly outwardly from the core barrel  172 . The flange  173  rests on the internal support ledge  101  of the reactor vessel  100 . The core barrel flange  173  has a plurality of threaded openings  174 . In the preferred embodiment there are three threaded openings  174 . The core barrel lower end  184  includes a radial support  186  which is coupled with the lower core support forging  179 . The lower core barrel radial support  186  may be welded to the lower core support forging  179 . The core barrel  172  is spaced apart from the reactor vessel  100 , forming a plenum  80  therebetween. 
     The lower core plate  176  is generally cylindrical and includes a plurality of openings  190 . The lower core plate  176  is spaced above the core support forging  179 . Baffle assembly  171  is disposed between upper core plate  128  and lower core plate  176 . As shown on FIG. 4, the baffle assembly  171  has a perimeter comprised of flat surfaces connected at 90° angles extending within the cylindrical perimeter of core barrel  172 . 
     Lower core support forging  179  is disposed below the lower core plate  176 . A plurality of lower core plate columns  177  extend upwardly from the lower core support forging  179 , supporting the lower core plate  176 . The core support forging  179  also includes a plurality of openings  192  which are aligned with the openings  190  in the lower core plate  176 . The core support forging  179  is supported by the core support columns  200  which extend downwardly therefrom and pass through the lower head  102  of the reactor vessel  100 . Each core support column  200  includes a coupling  201  to attach the support column to the lower core support forging  179 . The core support columns  200  are stabilized by a tie plate assembly  180 . The tie plate assembly  180  is generally circular and includes a plurality of openings  181  to allow support columns  200  to pass therethrough. A portion of the core support columns  200  are coupled with a secondary core support  196 . The secondary core support  196  is a disk having an arcuate bottom surface which is adapted to match the curvature of the reactor vessel  100 . The core support columns  200  are hollow and enclose instrumentation  204 . The instrumentation  204  extends through support means  26  and columns  200  from the outer side of the reactor vessel  100  through the lower head  102  and through core support forging  179 . The instrumentation  204  is further extended through lower core plate support columns  177  and through lower core plate  176  and extending into the reactor core  220 . 
     The nuclear fuel cells  222  are disposed within the core barrel lower portion  176  between the upper core plate  128  and the lower core plate  176  and within the baffle assembly  171 . This area is the reactor core  220 . A plurality of control rod clusters  109  may be inserted in or removed from the reactor core  220  as required using the control rod drive shaft  108 . 
     In operation, water passes through an inlet nozzle  133  into the plenum  80  between the reactor vessel  100  and the core barrel  172 . The water is drawn downwards towards the lower end of the reactor vessel  100 . As the water passes below the lower core support forging  179  it is drawn upwards through the openings  190 ,  192  in the lower core forging and lower core plate. The water passes into the reactor core  220  where it is heated by the fuel cells  222 . The heated water rises through the reactor core  220  and passes through the plurality of openings in the upper core plate  129 . The heated water then exits the reactor vessel  100  through the outlet nozzle  134 . 
     Maintenance of the upper internal assembly  120  is well known in the prior art. To reach the upper internal assembly  120 , the upper head  106  of the reactor vessel  100  and associated components are removed. The upper internal assembly  120  can also be removed. With the upper internal assembly  120  removed, the fuel cells  222  may be removed from the reactor core  220 . (As shown in FIGS. 3 and 4) When this operation is complete, only the lower internal assembly  170 , as shown in FIG. 3, remains within the reactor vessel  100 . 
     FIGS. 5-9 show an up-ending device according to the present invention. The up-ending device allows the removal of the lower internal assembly  170  from the reactor vessel  100  so that the lower internal assembly  170  may be inverted for maintenance operations. The up-ending device includes a frame assembly  400  (shown in FIGS. 9A-9E) and a spider assembly  500  (shown in FIG.  7 D). The spider assembly  500  is, generally, fitted within the core barrel  172  and baffle assembly  171  to support the baffle assembly  171  and core barrel lower portion  172  during the up-ending procedure. The frame  400  is fitted about the core barrel  172  and is attached to the overhead polar crane  70 . 
     As shown in FIGS. 7A-7D, the spider assembly  500  includes a central column  510  and at least one baffle support plate assembly  520 . In the preferred embodiment, there are three baffle support plate assemblies  520 ,  522 ,  524 . Central column  510  includes a means to support baffle support plate assemblies  520 ,  522 ,  524 . In the preferred embodiment the support means is a first, second and third set of intermittent partial flanges  516 ,  517 ,  518 . The first set of intermittent partial flanges  516  is located on the lower portion of central column  510 . A second set of intermittent partial flanges  517  is located on the medial portion of central column  510 . The third set of intermittent partial flanges  518  is located at the top of central column  510 . Spider assembly central column  510  includes a plurality of lower projections  512  which are sized to engage lower core plate openings  190 . The spider assembly central column  510  further includes a lifting bale  514  located at its upper end. 
     As shown on FIG. 4, the baffle assembly  171  has a perimeter comprised of flat surfaces connected at 90° angles extending within the cylindrical perimeter of the core barrel lower portion  172 . The baffle support plate assemblies  520 ,  522 ,  524  are shaped to fit within the jagged perimeter of the baffle assembly  171 , that is, the baffle support plate assemblies  520 ,  522 ,  524  have the same cross-sectional shape as the baffle assembly  171 . The baffle support plate assemblies  520 ,  522 ,  524  further include a medial hole  526  which is sized to fit around a spider assembly central column  510 . Each baffle support plate assembly  520 ,  522 ,  524  includes a plurality of lifting rings  527  which may be coupled with a lifting device, such as crane  70 . The baffle support plate assemblies  520 ,  522 ,  524  further include a plurality of plunger assemblies  530  mounted adjacent to the outer perimeter of the baffle support plates  520 ,  522 ,  524 . The plunger assemblies  530  act as an engaging means to secure the baffle assembly  171 . 
     As shown in FIGS. 6A and 6B, the plunger assembly includes a horizontal hollow tubular member  532  attached to a baffle support plate  520 ,  522 ,  524 . A plunger head  534   a  is disposed within the hollow tubular member  532 . The hollow tubular member  532  further includes an elongated opening slot  533  on at least one side, preferably on two sides adjacent to the plunger head  534   a . A rotatable vertical member  536  extends upwardly at a generally 90° angle from a baffle support plate  520  and through tubular member  532 . The top of vertical member  536  include a plurality of flat surfaces  542 , which may be coupled to a plunger engaging tool  501  (shown in FIG.  7 A). The vertical member  536  includes an upper threaded portion  538 . A collar  544  having a threaded inner surface is disposed on vertical member  536  engaging threaded portion  538 . Collar  544  is coupled to one end of a diagonal member  546 . The diagonal member  546  is coupled at the other end to plunger head  534   a  through opening  533 . In operation, as vertical member  536  is rotated, collar  544  moves vertically causing the lower end of diagonal member  546  to move plunger head  534   a  horizontally. As the plunger head  534   a  is moved horizontally, it may be biased against baffle assembly  171 . The plunger head  534   a  may be flat, as shown on FIGS. 6A and 6B, or may be contoured, as shown on FIG.  6 C. As shown on FIG. 5, the plungers  530  are preferably evenly disposed about baffle support plates  520 ,  522 ,  524 . Plungers  530  which are disposed adjacent to flat sides of the baffle assembly  171  will have a flat head  534   a . A plunger  530  disposed adjacent to corners of baffle assembly  171  and will have contoured heads  534   b.    
     As shown in FIGS. 7A-7D, the spider assembly  500  is installed by attaching the lowest baffle support plate assembly  520  to central column  510 . Central column  510  is passed through the medial opening on baffle support plate assembly  520 , and the baffle support plate assembly  520  is lowered until it rests upon partial flange  516 . Cutouts  519 , as shown in FIG. 5, allow baffle support plate  520  to pass over partial flanges  517 ,  518 . Using polar crane  70  attached to lifting bale  514 , central column  510  and baffle support plate assembly  520  is inserted in the lower internal assembly  170 . The central column  510  is lowered until lower projections  512  are mounted within lower core plate openings  190 . Once the column  510  and the first baffle support plate  520  are positioned, the plurality of plunger assemblies  530  on are engaged the first baffle support plate  520  by rotating each vertical member  536  until each plunger head  534   a ,  534   b  engages baffle assembly  171 . As shown in FIG. 7B a second tier baffle support plate  522  is then lowered into place until positioned on the second set of partial flanges  517  in the medial portion of spider assembly central column  510 . The baffle support plate assembly  522  may be coupled to the overhead crane  70  by lifting rings  527 . Again, once the baffle support plate assembly  522  is positioned, plunger assemblies  530  are engaged with the baffle assembly  171 . As shown in FIG. 7C, baffle support plate assembly support columns  560  may be installed on the second tier baffle support plate assembly  522  to support the third tier baffle support plate assembly  524 . The third tier baffle support plate assembly  524  is then lowered into the lower internal assembly  170  until the third tier baffle support plate assembly  524  is generally aligned with the top of spider assembly central column  510 . Third tier baffle support plate assembly  520  rests upon partial flange  518  located at the top of the spider assembly central column  510 . Again, the plunger assemblies  530  are engaged to secure the baffle assembly  171 . 
     As shown on FIG. 7D the spider assembly further includes an upper brace assembly  581  which includes a lower baffle support ring  582 , a plurality of hollow support columns  584  and an upper lifting plate assembly  590 . Hollow columns  584  are disposed below lifting plate assembly  590 . Ring  582  rests upon the upper edge of baffle assembly  171 . As shown in FIG. 7E, the support columns  584  each have a lower end  585  which includes a threaded opening  586 . A height adjustment means, such as a floatable pad  588  coupled to a threaded rod  589 , is disposed within threaded opening  586 . The support columns  584  are coupled to the lower side  583  of upper lifting plate assembly  590  and are aligned with ring  582 . 
     As shown in FIG. 8A lifting plate assembly  590  includes a generally circular planar disk  591  having a diameter approximately equal to the core barrel upper flange  173 . Disk  591  includes openings  593  which are aligned with hollow support columns  584 . Openings  593  allow access to the interior of the support columns  584  so that a tool may be inserted to rotate threaded rod  589 , thereby biasing pad  588  against ring  582 . When lifting plate assembly  590  is lowered onto the lower internal assembly  170 , the lower end of the support columns are adjacent to ring  582 . Lifting plate assembly  590  further includes two parallel cross bars  602 ,  604  disposed on disk lower surface  583 . Cross bars  602 ,  604  include a plurality of threaded harness holes  610 ,  612 ,  614 ,  616 , one each located at each end of the cross bars  602 ,  604 . When the lifting plate assembly  590  is installed, only cross bars  602 ,  604  contact core barrel upper flange  173 . Thus, reducing the possibility of damaging the flange surface. 
     Lifting plate assembly  590  further includes an attaching means and a lifting harness attachment means  620 . The preferred embodiment of the attaching means and the lifting harness attachment means  620  are a plurality of threaded fasteners  620  which extend through disk  591 . In the most preferred embodiment, there are three fasteners which are threaded into lower internal assembly flange threaded openings  174  (shown on FIG.  3 ). By installing the threaded fasteners through the lifting plate assembly  590 , the lifting plate assembly  590  is attached to the lower internal assembly  170 . The threaded fasteners  620  are coupleable to a lifting harness. The fasteners may have, for example, threaded bore holes  620  which a harness  800  (described below) may engage. 
     Thus, when installed the spider assembly  500  supplies a radial force, through plungers  530 , to baffle assembly  171  as well as a compressive force, through ring  582 . Additionally, lifting plate assembly  590  provides a secure attachment to the lower internal assembly  170 . 
     As shown on FIGS. 9A-9E, the frame assembly  400  has two mirror image sides  401 ,  402  (Side  401  is shown in FIG. 9A) which are spaced apart by cross braces  425 ,  426 ,  427 ,  428  (shown in FIG.  9 B). Accordingly, it is understood that certain members, e.g. braces  430 ,  432  (shown in FIG. 9A) on side  401 , have unseen counterparts on side  402 . The frame assembly  400  includes first members  410 ,  412 , second members  414 ,  416 , front members  418 ,  420  and rear members  422 ,  424 . There are additionally cross braces  430 ,  432 ,  434 ,  436  and  438 . Lower plate assembly  440  (shown in FIG. 9B) is disposed between second members  414 ,  416 . Shielding plates  450 ,  452  are disposed adjacent to second members  414 ,  416 . The frame  400  further includes secondary core support saddle  460 , tie plate assembly support saddle  464  and core barrel support saddles  476 ,  477 . 
     As shown on FIG. 9A, side  401  (which is mirrored, but not shown on side  402 ) of the frame  400  is generally rectangular and includes a first member  410  which has a front end  480  and a rear end  481 . First member rear end  481  is coupled to one end of end of rear member  422  at a 90° angle. First member front end  480  is coupled to one end of end of front member  418  at a 90° angle. Second member  414  has a front end  484  and a rear end  485 . The ends of front member  418  and rear member  422  opposite the connection with first member  410  are coupled to second member  414 . Second member rear end  485  is coupled to one end of rear member  422  at a 90° angle. Second member front end  484  is coupled to one end of end of front member  418  at a 90° angle. 
     Each end of rear member  422  includes an arcuate corner portions  453 ,  454  which each have a outer surface  431 ,  433 . As will be described below, the frame assembly is rotated on outer surfaces,  431 ,  433 . Front member  418  and rear member  422  are also connected by a plurality of braces  430 ,  432 ,  434 ,  436 ,  438  which are connected to tabs  429  on the front member  418  and tabs  421  on the rear member  422 . As shown on FIG. 9B, cross braces  437 ,  439  are disposed between rear members  422 ,  424 . 
     As shown on FIGS. 9B-9D, sides  401 ,  402  are spaced apart by braces  425 ,  426 ,  427 ,  428 . Brace  425  is disposed between sides  401 ,  402  adjacent to rear members  422 ,  424  upper rounded corner  453 . Braces  426  and  427  are disposed between sides  401 ,  402  spaced along the medial portion of rear members  422 ,  424 . Brace  428  is disposed between sides  401 ,  402  at rear member lower rounded corner  433 . 
     In the preferred embodiment, frame assembly second members  414 ,  416  are I-beams having an upper flange  415 ,  417 . The I-beam upper flange  415 ,  417  is above the bottom surface of second members  414 ,  416 . Each upper flange  415 ,  417  has a plurality of threaded fastener holes (not shown). Detachable frame lower plate assembly includes a planar member  445 . Frame lower plate planar member  445  is attached by fasteners  441  to upper flange  415 ,  417 . Frame lower plate assembly  440  further includes lifting rings  442  disposed on the outer surface of frame lower plate planar member  445 . Frame lower plate assembly lifting rings  442  may be coupled to a lifting means such as crane  70 . As shown on FIG. 9B, a plurality of lower internal assembly support columns  443  extend upwardly from the interior surface of frame lower plate planar member  445  terminating in distal ends  447 . A lower internal assembly support arc  446  is disposed at the distal ends of the plurality of lower internal assembly support columns  443 . 
     As shown on FIG. 9B, core barrel saddles  476 ,  477  are disposed between rear members  422 ,  424  adjacent to braces  426 ,  427 . In the preferred embodiment, core barrel saddle  476  is integral to brace  426  and core barrel saddle  477  is integral to brace  427 . As shown on FIG. 9D, each core barrel saddles  476 ,  477  includes an upper arcuate surface  478 ,  479  which is sized to fit the outer diameter of core barrel  172 . Tie plate assembly support saddle  464  includes a support member  465  and a saddle pad  466 . Saddle pad  466  includes an arcuate surface  467  which has a curvature matching that of tie plate assembly  180 . Secondary core support saddle  460  includes a support member  461  and a secondary core support saddle  462 . Secondary core support saddle  462  also includes an arcuate surface  463  which is sized to match the curvature of the secondary core support  196 . When the lower internal assembly  170  is installed within Frame  400 , secondary core support  196  is adjacent to secondary core support saddle  460 . Tie plate assembly  180  is adjacent to tie plate assembly support saddle  464 . Core barrel  172  is adjacent to core barrel saddles  476 ,  477 . When the up-ender device is laid horizontally each of these components will rest upon the respective support saddles. 
     Lifting lugs  490  are located at each corner of sides  401 ,  402 . As shown on FIG. 9C, each lifting lug  490  includes a cylindrical base  491  and an outer disk  492 . The outer disk  492  has a larger diameter than the cylindrical base  491 . 
     In operation, the lower internal assembly  170  fits within sides  401 ,  402  of frame assembly  400 . In the upright orientation, the lower core support forging  179  rests upon lower internal assembly support arc  446 . L-shaped retainer  406  prevents the lower internal assembly  170  from tipping out of frame  400 . Crane  70  is connected to lifting lugs  490  and is used to rotate the frame  400 . When in the horizontal orientation, core barrel saddles  476 ,  477 , tie plate assembly support saddle  464 , and secondary core support saddle  460  support the lower internal assembly  170 . When in the inverted upright orientation the lower internal assembly  170  rests upon lifting plate assembly  590 . 
     FIGS. 11A-11H show the up-ending procedure according to the present invention. The up-ending procedure is accomplished as follows. While the internal assemblies  120 ,  170  are still with in reactor vessel  100  (not shown), the upper internal assembly  120  and fuel cells  222  are removed as described above. The core support columns  200  are de-coupled from the lower internal assembly  170 . As is known in the prior art, the lower internal assembly  170  is then removed from the reactor vessel  100  and placed on storage stands  42 ,  44 . As shown in FIG. 11A, up-ending frame  400  is then positioned on the floor  12  between pit  20  and the maintenance bay  40 . As shown in FIGS. 7A-7D, the spider assembly  500  is then installed, as described above, to support the baffle assembly  171  of the lower internal assembly  170 . Installing the spider assembly  500  includes coupling the lifting plate  590  to the core barrel upper flange  173 . The polar crane  70  is then coupled to the lifting plate  590 . In the preferred embodiment, a harness  800  having three lifting rods  801  is coupled to lifting plate assembly  590  through lifting means  620 . In the preferred embodiment, the lifting means  620  are threaded fasteners with threaded bore holes  622 , and lifting rods  801  include threaded tips that may be engaged with the threaded bore holes  622 . Crane  70  may then lift the lower internal assembly  170  off maintenance bay support structures  42 ,  44 . As shown on FIG. 11B, using polar crane  70 , the lower internal assembly  170  is then lifted to a position adjacent to the up-ending frame  400 . The lower internal assembly  170  is then translated horizontally into the up-ending frame  400 . Once positioned within frame  400 , the lower internal assembly  170  is lowered until lower core support forging  179  rests on lower internal assembly support arc  446 . As shown on FIG. 9C, cross bar  405  is attached between frame first members  410 ,  412 . Cross bar  405  includes an L-shaped retainer  406  disposed on the medial portion of cross bar  405 . The L-shaped retainer includes a tab  407  which extends downwardly adjacent to core barrel  172 . Tab  407  prevents the lower internals  170  from tipping out of frame  400 . As shown in FIG. 11C, the up-ending frame  400 , which now holds lower internal assembly  170 , is rotated on lower rounded corners  431  into a horizontal orientation. As shown in FIG. 11D, because the floor  12  in the preferred embodiment is at a higher elevation than maintenance bay floor  41 . An additional A-frame support member  45  may be installed on maintenance bay storage stands  42 ,  44 . Frame  400  is then translated horizontally until lower members  422 ,  424  rest on A-frame  45 . As shown in FIG. 11E, the up-ending frame  400  is then pivoted about upper rounded corners  431 ,  433  until the frame  400  is in the inverted, vertical orientation. As shown in FIG. 11F, the up-ending frame  400  is then rotated 180 degrees about a central axis so that the open side of frame  400  is adjacent to the maintenance bay  40 . The crane  70  is then detached from the frame assembly  400  and coupled to the lower internal assembly  170 . In the preferred embodiment, the crane  70  is coupled to a four legged harness  802 . Each leg of the four-legged harness  802  is a rod  804  having a threaded tip  805 . The rods  804  pass through one of the harness openings  449  on frame lower plate assembly  440 . Each rod  804  is lowered along the outside of the lower internal assembly  170  until each rod tip  805  engages threaded harness attachment holes  610 ,  612 ,  614 ,  616  on cross bars  602 ,  604 . The crane  70  then lifts and translates the lower internal assembly  170  horizontally out of up-ending frame  400  and lowers the lower internal assembly  170  on to maintenance bay storage stands  42 ,  44 . Thus, as shown in FIG. 11H, the procedure terminates with the lower internal assembly  170  being in an inverted orientation on the maintenance storage stands  42 ,  44 . The re-inversion procedure consists of performing the above steps in reverse order. 
     While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.