Patent Number: 
Section: description

FIG. 1 shows an embodiment of a removable rail assembly 10 formed in accordance with the teachings of this invention. The rail assembly 10 includes a rail guide 12, a joint connector 14, and a support rail 24. The rail guide 12 is a T-shaped member having a horizontally extending base 16 and an upwardly extending center portion 18. The center portion 18 supports a guide 20. The guide 20 extends horizontally outward from the center portion 18 at a location below the top 22 of the center portion 18. The location of the guide 20 below the top 22 of the center portion 18 should be sufficient to support the wheels or other portions of the spent fuel handling machine traveling along the rail guide 12. The rail guide is coupled to a support rail 24 as illustrated in FIGS. 2 and 4 using widely known techniques. As shown in FIG. 1, the rail guide 12 extends beyond the ends of the support rail 24 and onto a rail trench (not shown). The ends of the rail assembly 10 are each coupled to threaded rods (not shown) embedded in the floor 36. This arrangement not only provides an anchor point for the rail ends but also increases the stability of the joint between the rail assembly 10 and the fixed rails 11 due to the downward force on the rail guide 12. The joint between the rail assembly 10 and the fixed rails 11 is established by a joint connector 14. As shown in FIG. 1, the joint connector 14 is formed as a tongue and groove joint having a tapered parting line, with the tongue located on the rail assembly 10. In a preferred embodiment, the tongue is approximately one-half the depth of the rail guide 12. This design establishes a tight fit between the removable rail assembly 10 and adjacent fixed rails 11, while simultaneously decreasing the force necessary to separate the rail assembly 10 from adjacent fixed rails 11 during removal due to the tapered parting line. It will be appreciated, however, that other methods may be used to join the rail assembly 10 to adjacent fixed rails 11. As illustrated in FIGS. 2, 4 and 7, the support rail 24 includes an I-beam cross-section. However, it will be appreciated that in order to simplify installation, the support rail 24 preferably has a cross-sectional area identical to that used to support the fixed rails 11. The support rail 24 possesses a bending strength that limits the deflection of the spent fuel handling machine mast, and thus the radial loading of the mast bearings. The support rail 24 is mounted in the operating floor 36, and is located above the spent fuel storage pool. The support rail 24 includes a depth having a length and terminates above the water level of the spent fuel storage pool 37. However, it will be appreciated, that it may not be possible to prevent the rail support 24 from extending into the water of the spent fuel storage pool 37. The support rail 24 is mounted within the operating floor 36 such that the lower flange portion 30xe2x80x2 is supported by an embedded plate 34. The embedded plate 34 is anchored to a recessed surface 42 defined by the floor 36, thus, providing foundational support for the rail assembly 10. The embedded plate 34 is coupled to the lower flange portion 30xe2x80x2 of the support rail 24 by attachment bolts 21. Additionally, the embedded plate 34 supports an alignment pin 26. The alignment pin 26 extends upwards from the embedded plate 34, and is received in an opening defined by the support rail 24 flange portions 30, 30xe2x80x2. The alignment pin 26 provides a guide that aids the removal and installation of the rail assembly 10. Further, the embedded plate 34 defines an opening for receiving a jacking screw 28 for loosening the joint connector 14 by slightly raising the removable rail assembly 10. At least one jacking screw 28 is located at each end of the support rail 24. In the preferred embodiment, the support rail 24 supports a pair of jacking screws 28, as illustrated in FIGS. 1-4. Each jacking screw 28 is coupled to the support rail 24 by inserting each jacking screw 28 through mating holes in the support rail 24 flange portions 30, 30xe2x80x2, wherein the openings in the flange portions 30, 30xe2x80x2 align with mating holes in the embedded plate 34. Each jacking screw 28 provides a force along the length of the rail assembly 10 that causes a loosening of the joint connector 14 when the jacking screw 28 is tightened. In the preferred embodiment, each jacking screw 28 induces a uniform lifting force along the length of the rail assembly 10. Once the joint connector 14 has been loosened, the support rail 24 is coupled to a lifting crane (not shown) and transferred to a storage area. The lifting crane is coupled to the support rail 24 flange 30 using commonly known techniques. When installed in the floor 36, the top flange 30 of each removable rail assembly 10 is flush with the bottom of the floor 36 rail sections (not shown). A shim plate 38, positioned between the recessed surface 42 and the embedded plate 34, may be needed to raise the rail assembly 10 to the desired height. A bolt 44 couples the shim plate 38 to the support rail 24. The height of the shim plate 38 may be adjusted as needed to obtain the preferred height for the rail assembly 10. FIG. 7 depicts a plan view of the fuel handling system in the spent fuel handling building showing the location of the removable rail assembly 10. When spent fuel is removed from the reactor, it is placed horizontally onto a carriage in the refueling canal 50. When the fuel reaches the spent fuel handling building, a fuel transfer system upender 52 moves the spent fuel from the horizontal to a vertical position. The spent fuel can then be picked up and placed into one of the spent fuel racks 54. The removable rail assembly 10 is useful, for example, when the upender 52 requires repair or other access to a compact space. FIG. 5 shows a second embodiment of a removable rail assembly 100. The removable rail assembly 100 shares common features with the embodiment shown in FIG. 1. It will be appreciated that common reference numerals will be used to identify common features. Except for the jacking screw 32 received in the top surface 22, the rail assembly 100 is functionally and structurally identical to the embodiment described in FIGS. 1-4. The removable rail assembly 100 includes a rail guide 12xe2x80x2, a joint connector 14 and a support rail 24. The rail guide 12xe2x80x2 includes a T-shaped member having a horizontally extending base 16 and an upwardly extending center portion 18. The center portion 19 includes a guide 20 that extends horizontally outward from the rail guide 12xe2x80x2 at a position below the top surface 22. The top surface 22 supports a jacking screw 32. As shown in FIGS. 5 and 6, one jacking screw 32 is received in each end 40, 40xe2x80x2 of the rail guide 12xe2x80x2. The jacking screw 32 is received in a mating opening defined by the top surface 22 of the rail guide 12xe2x80x2. The jacking screw 32 extends through the depth of the rail guide 12 and is supported by the operating floor 36. As shown in FIGS. 5 and 6, one jacking 32 screw is supported by the top surface 22 in that portion of the rail guide 12xe2x80x2 that extends beyond the support rail 24. Consequently, the jacking screw 32 is located on the top surface 22 between the joint connector 14 and the rail support 24. The joint connector 14 couples each end of the rail guide 12xe2x80x2 to a fixed rail 11. The joint connector 14 is a tongue and groove joint of the type previously described. Tightening the jacking screw 32 induces a force along the rail assembly 100, thus, causing loosening of the joint between the fixed rail 11 and the rail guide 12xe2x80x2. In the preferred embodiment, the jacking screw 32 induces a uniform lifting force along the rail assembly 100. The support rail 24 supports the rail guide 12xe2x80x2 using known techniques. The support rail 24, as previously discussed, is received within a recess defined by the operating floor 36. The lower flange 30xe2x80x2 of the support rail 24 is received in the recess and is supported by an embedded plate 34, as illustrated by FIG. 6. The embedded plate 34, as previously described, supports a shim plate 38, and receives in mating openings an alignment pin 26 and at least one other jacking screw 28. The alignment pin 26 facilitates proper alignment of the rail guide 12xe2x80x2 and the support rail 24. The jacking screw 28, when tightened, induces a force along the rail assembly 100. In the preferred embodiment, the lifting force induced along the rail guide 12xe2x80x2 is of a uniform magnitude. It will be appreciated that the jacking screws 28, 32 may be operated independently or cooperatively to facilitate loosening of the joint connector 14. There are a variety of configurations that may be employed to fabricate the removable rail assemblies 10 and 100. Thus, the disclosed embodiments are given to illustrate the invention. However, the disclosed embodiments are not intended to limit the scope and spirit of the invention. Therefore, the invention should be limited only by the appended claims.