Patent Number: 039309380
Section: summary

Background of the Invention 1. Field of the Invention In nuclear reactors of BWR type the control rods are positioned, as a rule, between the fuel assemblies and have cruciform cross-section with their central part located in the free space between four adjacent fuel assemblies and the wings projecting cruciformly from the central part, each of said wings being located between two adjacent assemblies. 2. The Prior Art Primarily for reasons of economy of fuel, it is desirable, however, to be able to position the control rods inside the fuel assembly and to make them in the form of finger control rods and let them run in guide tubes between the fuel rods. In this arrangement, new problems arise concerning the attachment of the control rods to the control drive and their locking of the attachment device against involuntary influence of the attachment device. SUMMARY OF THE INVENTION The present invention relates to a means for attachment and locking of finger control rods in fuel assemblies for nuclear reactors of BWR type. According to the invention, individual control rods or groups thereof are attached, with the help of known fastening devices, at their lower end to a yoke or similar element which can be influenced by the control drive of the control rods. The fastening devices are lockable against involuntary movement by means of locking devices which are arranged in such a manner that they can be operated when the control rods are in their upper position in the core. In a particularly preferred embodiment of the invention, the locking device is applied at the top of the control rods, said top projecting above or being level with the upper part of the core when the control rods are in their topmost position. Because the locking devices are then visible and easily accessible, the work with the rods is considerably facilitated.