Patent Number: 045377413
Section: summary

BACKGROUND OF THE INVENTION The present invention relates generally to automated loading of fuel assemblies for nuclear reactors. It comprises a funnel assembly temporarily mounted on a length of cladding to facilitate automated loading procedures. This disclosure relates to a unique funnel assembly that is frictionally held in place at the open end of a length of cladding to present an enlarged diameter extension to facilitate loading of fuel pellets. Prior devices for automatically filling fuel pellets within lengths of cladding have used stationary feeding heads having tapered inner surfaces for guiding the pellets into an abutting open end of the cladding. Examples are shown in U.S. Pat. No. 3,746,190 (element 24) and U.S. Pat. No. 4,158,601 (element 88). When designing a fuel loading system that is totally automated, very careful attention must be directed to contamination difficulties. Merely contacting a feed head with the open cylindrical end of a length of cladding presents substantial possibilities of contamination as a result of such simple abutting contact. The present disclosure addresses this problem by utilizing a discardable funnel mounted within each length of cladding and by protecting the outer surfaces of both the funnel and cladding by utilization of an encircling length of shrink tubing. SUMMARY OF THE INVENTION It is an object of this invention to minimize spread of contamination at the open end of cladding which has been loaded with fuel pellets by automated equipment by providing a discardable funnel and protective length of shrink tubing which can be removed from the cladding immediately after the loading sequence. Another object of the invention is to provide a funnel assembly at the open end of a length of cladding which can be readily removed from the cladding by pulling it as the cladding is retracted. Another object of the invention is to provide such a funnel assembly which is relatively inexpensive and which does not substantially add to the length or bulk of the cladding. Another object of the invention is to incorporate within the funnel assembly a protective covering of shrink tubing which assists in preventing particles from being imbedded within the outer surface of the cladding by their engagement by contacting sealing elements. Additional objects, advantages and novel features of the invention will be set forth in part by the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. To achieve the foregoing and other objects and in accordance with the purposes of the present invention as embodied and broadly described herein, the apparatus of this invention may comprise a funnel having an enlarged outer open end leading to a reduced diameter neck at least partially inserted into the open axial end of a length of cladding as a coaxial extension of it. A continuous length of tubing is shrunk about both the cladding and the funnel to maintain them as a unit during reception of fuel into the cladding through the funnel open end. The tubing and funnel are readily removable by engaging the tubing and pulling it from the cladding as the cladding is retracted. A rearwardly-facing shoulder beneath the shrink tubing facilitates such engagement. Removal of the funnel assembly from the cladding is preferably accomplished immediately after the insertion of fuel pellets.