Patent Number: 050892207
Section: description

In FIG. 2, 7 designates the fuel assembly in the form of an elongated multi-corner channel with a wall 6. The fuel assembly 7 accomodates spacers 8 with windows 10 of a known type. FIG. 3 shows one of the same spacers 8 seen from above with fuel rods 1. FIG. 4 schematically shows a spacer 8 provided with deflection fins 9 in the windows 10 which extend in the downstream direction of coolant flow and include portions which extend inwardly towards a center line of the channel and terminate at a tip (free end) 9a. To be able easily to insert a bundle of fuel rods with spacers into the fuel assembly 7, each spacer 8 is provided with guide studs 11 which, however, are too small to have any guiding effect on the coolant flowing past. The frame of the spacer 8 consists of a metal band of, for example, Inconel which is placed on edge. The lower edge of the band, i.e., its upstream outer portion 12 , has been arranged, around the spacer 8, drawn in towards the centre of the spacer 8. When the bundle of fuel rods with the spacer 8 is located in the fuel assembly 7, this leads to the creation of a pocket 13 between the assembly wall 6 and the drawn-in outer portion 12 of the spacer 8. So that the film of cooling water flowing along the assembly wall 6 shall not be stopped in this pocket 13, openings 14 have been provided through the frame of the spacer 8 below each deflection fin 9. FIGS. 6 and 7 show substantially the same spacer 8, with the difference that the tip (free-end) 9a of the deflection fin 9 is connected by means of a supporting band 15 to a downstream edge of the window 10 in order to obtain a somewhat more stable design. The invention functions in such a way that the elongated deflection fins 9 conduct cooling water from the region at the fuel assembly wall 6 in towards the centre of the fuel rod bundle, thus improving the cooling thereof. That part of the cooling water which is led into the pocket 13 flows through the openings 14 and contacts the deflection fins 9 which, as mentioned above, conduct the cooling water towards the centre of the spacer.