Abstract: A securing device for a control rod in a nuclear plant contains a control rod drive and a drive housing, which encloses the control rod drive and which is configured to be fed through a reactor pressure wall. The aim of the securing device is to prevent, in the most reliable manner possible, the control rod from being extended in an uncontrolled manner. Furthermore, the securing device should be as inexpensive as possible and should pose the slightest obstacle possible to installation work. For this purpose, the drive housing has at least one coupling element for forming a force-locked and/or form-fit connection of the drive housing to the reactor pressure wall.

Abstract: A method for replacing bolts on core components of nuclear reactors includes machining away a bolt fastened at an installation site in a core component as well as the entire fastening of the bolt with an electroerosion machine. Machined-away bolt material is removed and caught with a filter. The bolt is then ejected from the core component with a closed force system. The installation site of the bolt is remachined with an accurate fit and a new bolt is subsequently inserted. An apparatus for replacing bolts on core components of nuclear reactors includes rails. An auxiliary platform is supported on the rails on both sides of a reactor pressure vessel. An auxiliary crane is disposed on the auxiliary platform and adjustable transverse to the rails. A tool carrier is guided on the auxiliary platform and suspended from the auxiliary crane. A tool is disposed on the tool carrier for replacing bolts on core components.