Patent Number: 062263439
Section: description

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 3 illustrates a first preferred embodiment of the invention. In this embodiment, a water rod 40 according to the invention has one or both of its ends machined to include threads 42. The threaded end of the water rod 40 is configured to be received in a threaded aperture 44 in a tie plate 46 of the fuel assembly. The threads 42 may be formed at the ends of the water rod 40 in any known manner. FIG. 4 illustrates a second embodiment of the water rod 40 according to the invention. In this embodiment, one or both ends is swaged to a narrower diameter than the remainder of the water rod 40. The swaged end or ends are then machined with threads for attachment to the tie plate 46. In a third embodiment of the invention, referring to FIG. 5, one of the water rod ends 48 is flared such that its diameter is greater than that of the tie plate aperture 44. In this embodiment, the water rod 40 must be inserted from either below the lower tie plate or above the upper tie plate. Also in this embodiment, the water rod may be keyed in a known manner to prevent the water rod from rotating. In a fourth embodiment of the invention, referring to FIG. 6, one or both of the ends of the water rod 40 may be configured with a bayonet fitting 50, including a slit 50a formed in the water rod 40 and a corresponding pin 50b in the tie plate aperture 44. Of course, the water rod 40 may be fitted with the pin 50b, and the tie plate may be configured to receive the pin in a corresponding slot 50a. In accordance with another aspect of the invention, referring to FIG. 7, an end insert 52 may be inserted into the water rod. The end insert 52 may be threaded into the water rod 40, press fit and secured by friction, or welded into the water rod 40. The end insert 52 may be configured to completely block flow of coolant into the water rod 40 or may be provided with flow holes 54 to regulate coolant flow and/or prevent significant debris from entering through the water rod. The end insert 52 may further serve as a filter to prevent a greater amount of debris from entering through the water rod. FIG. 8 illustrates an alternative to the additional aspect of the invention described in connection with FIG. 7. In particular, FIG. 8 illustrates an end cap 56 that is press fit, welded or threaded over the end of the water rod 40. Similar to the end insert 52, the end cap 56 may be closed to completely prevent coolant flow through the water rod 40, or the end cap 56 may include flow holes 54 and/or serve as a filter for debris. While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.