ES360338A1 - Improvements in and relating to Nuclear Fuel Assemblies - Google Patents

Abstract

A fuel assembly comprises a plurality of fuel pencils 2 carried in an annular outer sleeve by means of an end support grid 8 (Fig. 3) made up of a metal sheet suitably folded back and forth so as to form a castellated profile with rectangular ends and parallel side strips 10, 11. These sides are in the form of continuous flat strips and are located in planes parallel to planes which are tangent to the fuel pencils 2. They are joined together alternately at the level of their top and bottom edges by means of narrow junction bridges 12, 13 obtained at the time of folding the metal sheet by previously cutting out suitable spaces 14. Each bridge 12 or 13 is provided with a central hole 15 into which end pins 4 forming extensions of the fuel elements 2 are inserted, and each is associated with a yoke 16 or 17 which is placed over the strips 10, 11 on the opposite side to the bridge. Each yoke 16 or 17 is provided with two lateral grooves 18, 19 which engage the edges of the strips 10, 11 and with a central hole 20 which receives an end pin 4. The fuel pencils 2 are locked in position by means of nuts 21 which are screwed on to threaded portions 6 of the end pins 4. The nuts 21 are locked at the end of travel by means of check-washers 22 provided with internal tongues which engage in grooves 23 in the end pins 4. In an alternative construction (Fig. 4), the support grid is no longer formed from a single metal sheet but consists of a series of parallel metal strips 30 maintained in constant spaced relation by means of connecting lugs 31 welded to the lower edges of the strips 30 and each provided with a central hole 32 for the insertion of a fuel pencil end pin.