Patent Number: 06178219&
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the figures of the drawing as a whole, there is seen a holder 1 disposed in a boiling water reactor, through the use of which fuel rods, but also other components, for example sensor lances, can be held. The upper termination of the holder 1 is formed by a core grid 2 which has a plurality of orifices 2a. Fuel elements or other components are positioned in these orifices 2a. The core grid 2 may be constructed from metal sheets. More preferably, however, it is forged, thus ensuring a high degree of stability. Fuel elements can be pushed into the orifices 2a in the core grid 2. All the fuel elements forming the so-called reactor core are surrounded laterally by a core shroud 3 in the boiling water reactor. In the event of an exchange of the core grid 2, a core grid 2 formed of of metal sheets is often replaced by a forged core grid 2 which is more stable. This new core grid 2 then has a lower height than the old core grid 2. An adapter ring 4 consequently has to be disposed between the core shroud 3 and core grid 2, so that the fuel elements remain completely surrounded. The adapter ring 4 is connected to the forged core grid 2 without a welded joint. A welded joint would introduce a large amount of heat into the material of the core grid 2, but also into that of the adapter ring 4 making it particularly susceptible to corrosion, in particular to stress cracking corrosion. This susceptibility would be further reinforced by radiation in a boiling water reactor. The avoidance of a welded joint makes a high corrosion rate impossible. The adapter ring 4 can be held in recesses 2b, 3b in the core grid 2 and in the core shroud 3. The adapter ring can be inserted loosely, or be held with a sliding or snug fit. In a particularly advantageous embodiment, the adapter ring 4 is shrink-fitted on the core grid 2. In addition, the adapter ring 4 can be secured in position through the use of connecting elements 5 which pass through it and engage into the core grid 2. The connecting elements 5 can be bolts.