[en] Bolting device, composed of ratchets and pins, not released during normal operation of the control rod assembly of a nuclear reactor but removable for repair or replacement of the control rod assembly

[en] In order to guarantee a safe and reliable discharge of the medium escaping due to the ventilation, it is planned that, in the external surface of the lock pointing to the top, three boreholes in a parallel line are positioned in alignment with the axis of the lock. One borehole meets coaxially on an exhaust air duct which forms a cross connection with the borehole. The borehole forms a cross connection with a third borehole, and this third borehole forms the discharge duct. At its free end, the discharge duct carries a coupling nipple. The boreholes are equipped with an identically constructed valve stem. The valve stem carries a valve cone, and for the installation of a round-cord ring it is equipped with a ring groove. (orig./HP)

[en] Reliability analysis is a method by which the degree of successful performance of a system, under certain stipulated conditions, may be expressed in quantitative terms. Techniques of quantitative reliability analysis for control rod drive systems, which are presented, consist in: drawing up of system block diagrams as basis for the reliability analysis for normal and scram operation; estimation of possible fault rates (''mean rates'') of system components; reliability analysis of the complete control systems (total number of control rod drive mechanisms) on the basis of the analysis of the indjvidual rod drives. (author)

[en] This paper describes a nuclear reactor having a control rod guide tube and an upper core plate, a pin-type mounting system for removably mounting the lower flange of a control rod guide tube over an opening in the upper core plate. It comprises: a pair of resilient pin members formed of stainless steel, mounted in passages formed through first opposing sides of the guide tube lower flange and resiliently and slidably receivable in a first pair of opposing bores formed on first opposing sides of the opening in the upper core plate to permit deflection thereof when the guide tube is subject to the usual shear loads associated with the operation of the nuclear reactor, the resilient pin members bearing substantially all of the usual shear load to which the guide tube is subjected. A paid of reinforcing pin members formed to stainless steel mounted on second opposing sides of the guide tube lower flange and slidably receivable in a second pair of bores formed on second opposing sides of the opening in the upper core plate

[en] A guide structure is described for aligning fuel assemblies of a nuclear reactor and for guiding control elements for telescoping movement within guide channels of fuel assemblies. (E.C.B.)

[en] An apparatus is described for retaining an undriven control component assembly disposed in a fuel assembly in a nuclear reactor of the type having a core grid plate. The first part of the mechanism involves a housing for the control component and the second part is a brace with a number of arms that reach under the grid plate. The brace and the housing are coupled together to firmly hold the control components in place even under strong flows of th coolant

[en] This patent describes a method of movably repositioning a control rod cluster assembly of a nuclear reactor relative to a plurality of fuel assemblies in the nuclear reactor within a maximum displacement composed of a multiplicity of separate successive single steps. It comprises performing a single-step repositioning of a control rod cluster assembly in a nuclear reactor by moving the control rod cluster assembly through soley a single step of such displacement; and repeating the single-step repositioning at a plurality of separate times during a given fuel cycle of the reactor to perform a sequence of at least more than one of the separate single-step repositionings of the control rod cluster assembly during the given fuel cycle of the nuclear reactor, the separate times being spaced from one another by periods of time during which the control rod cluster assembly remains stationary; the single-step repositioning being repeated at most once every month during a twelve month fuel cycle

[en] A control rod guide-tube assembly is described. It includes a hollow control rod guide-tube, having not less than one open end, a hollow cylindrical sleeve telescopically engaged above a part of the guide-tube, an annular groove cut in the outer surface of the sleeve, a collar around part of the guide-tube and the telescopically engaged sleeve, the collar and the ringed parts of the guide-tube and sleeve being joined to form a control rod guide-tube assembly in one piece

[en] This invention provides a control component structure comprising: a spider having a plurality of arms, at least one spider bore formed in said plurality of arms, said spider bore including an enlarged recess and a small recess with an upright truncated conical section forming a transition from the enlarged recess to the small recess, and a burnable poison rod including a tube terminating in transverse end, a plug with a chamfered end that leads into a cylindrical portion, said cylindrical portion of the plug snugly fitting within the tube and terminating in a radially protruding shoulder which engages the transverse end of the tube to which it is welded, and a stem protruding in the longitudinal direction from the central portion of the shoulder having a longitudinal stem bore extending through about half of the length of the stem, at least part of the stem which defines the stem bore being fixed within the truncated conical section, the enlarged recess and the small recess of the spider by outward deformation of that part of the stem in order to releasably attach the rod to the spider, said stem being adapted to substantially reshape itself by movement of the rod in a longitudinal direction with respect to the spider bore, while maintaining the structural integrity of the poison rod and maintaining the structural integrity of the spider

[en] This invention relates to improvements made to nuclear reactor fuel assemblies, particularly to the procedures and appliances for removably setting up, in the cross-bracing of fuel assemblies, rods of neutron absorbing burnable substances also called 'poisons'