Abstract: A nuclear reactor includes a pressure vessel enclosing a plenum, a core in the pressure vessel, a pressure-tight encapsulation in the pressure vessel communicating with the plenum, and control members passing through the encapsulation and having first and second control member segments. The second control member segment has an absorber part to be at least partly inserted into and retracted out of the core for controlling reactivity. The first control member segment has an outer drive part. A control drive is associated with the outer drive part for adjusting the control member along the longitudinal direction thereof. An antieject device for restraining ejection of the control member out of the pressure vessel due to a leak at the encapsulation includes a rod coupling having a disengageable coupling catch interconnecting the first and second control member segments and remaining in engagement during normal control motion of the control member and means for unlocking the coupling catch.

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.

Abstract: Accessory for a screw-tightening device having a support ring with hydraulic piston-cylinder assemblies as tensioning elements for pressure-vessel cover screws, the assemblies being disposable on a flange of the pressure-vessel cover, fastening nuts for the cover screws being loosenable and tightenable as well as transportable by the screw-tightening device, including a divided auxiliary ring having parting gaps formed in a circumferential region thereof corresponding to a circumferential region of the support ring at which parting gaps are likewise formed, the auxiliary ring and the support ring being mutually superimposable and clampable, the divided auxiliary ring having the parts thereof provided with respective means for engagement by a lifting tool, the rings having flange connections at the parting gaps thereof, the flange connections being disconnectible to form at least two separate arcuate units respectively including part of the support ring and part of the auxiliary ring clamped together for trans

Abstract: Transport and assembly apparatus for a screw-tightening device having a carrier ring seatable on a pressure-vessel cover for loosening and tightening fastening screws thereon includes a lift truck having an elevating platform whereon a carrier ring is mountable, means for pivoting the carrier ring about a horizontal axis, and means for vertically adjusting the carrier ring with the elevating platform.