Patent Number: 050842374
Section: summary

INTRODUCTION This invention relates to a side insertable spacer designed to permit rapid repair of irradiated fuel assemblies. Fuel assemblies for nuclear reactors are formed of a large number of long, parallel fuel rods. At each end of the assembly, there is a tie plate to which, in some designs, the fuel rods are attached. In other designs the fuel rods terminate short of the tie plates and the tie plates are connected to tie rods so as to form the framework for the assembly. Intermediate the tie plates there are a number of grid spacers formed of "egg crate" strips which serve to space the fuel rods and restrain them from vibration. At times there may be fretting of fuel rods at or adjacent to the tie plates so that it is desirable to insert additional grid spacers. In other cases, the grid spacers may be damaged in handling so that the replacement becomes necessary. In previous designs, it has been necessary to essentially disassemble the fuel bundle if new spacers are to be inserted. This is, of course, a difficult procedure, particularly since it will ordinarily be carried out on assemblies which have been irradiated in the nuclear reactor and have therefore become radioactive. BRIEF DESCRIPTION OF THE INVENTION Our invention provides a spacer which can be inserted into a finished fuel assembly without disassembling the latter. It is formed of two superposed "combs." Each comb includes an end strip corresponding in length to one side of the fuel assembly. Perpendicular to this end strip are a plurality of grid strips which engage the fuel rod. The grid strips are so constructed as to have spring members which press against the fuel rods. When the spacer is completely assembled, the superposed combs will extend at right angles or some other angle, depending on the shape of the assembly, to each other. Together they form a complete grid spacer which will hold the rods in position. The combs are of such structure that they can be remotely inserted into the assembly even under water by the use of long-handled tools.