GB1302060A - - Google Patents

Abstract

1302060 Fuel elements INTERATOM INTERNATIONALE ATOMREAKTORBAU GmbH 2 Oct 1970 [4 Oct 1969] 47069/70 Heading G6C A fuel element spacer grid comprises interfitting web plates la, 1b forming a rectangular lattice, the cells of which each house either a fuel pin 5 or a control rod guide tube 6. Each fuel pin 5 is in point contact with two spring strips 3 and two spacing strips 4, which strips do not extend through the cells housing guide tubes 6. The spacing strips 4 are omitted at the web plates 2 forming the outer boundary of the spacer grid, the spacing of the fuel pins 5 being ensured in this case by projections 8 pressed out of the plates 2. Each lattice cell housing a fuel pin 5 has one spring strip 3 and the oppositely disposed spacing strip 4 located at one end of the cell, the other pair of strips 3, 4 being located at the other end of the cell. Each spring strip 3 consists of short straight sections which bear against a plate 1a or 1b and of longer, bowed sections which, together with intermediate sections inclined at 60 degrees to the straight sections when the strip is not loaded, ensure an approximately linear spring characteristic. A projection pressed out of the centre of the bowed section ensures point contact with a fuel pin. Each spacing strip 4 has at regular intervals, extending in one direction U-shaped portions each with a pressedout projection against which a fuel pin makes point contact, and extending in the other direction pressed-out bosses which fit into holes in a plate 1a or 1b and are connected by spotwelding to the spring strip 3 situated on the other side of the plate. The plates la, 1b, 2 are made of a material having low neutron absorption, e.g. a Zr alloy, while the strips 3, 4 are made of a material having good spring properties, e.g. stainless steel or a Ni alloy. There is no metallurgical union between the strips and the plates, whereas the spring and spacing strips which are of like material are welded to one another.