[en] This patent describes a control rod guide thimble having a main hollow tube defining a substantial portion of the length of the guide thimble. It comprises: a lower tubular portion of the man hollow tube; and an auxiliary hollow tube having concentric exterior and interior surfaces, the auxiliary tube being inserted in the lower portion of the main hollow tube and having an outside diameter slightly less than an inside diameter of the main tube to permit a close fitting relationship between the exterior surface and the auxiliary tube and an interior surface of the main tube lower portion, the auxiliary tube having an upper end portion with an inside surface portion in axial cross-section flaring in inclined relation upwardly and outwardly to provide a tapered transition extending between and connecting the interior surface of the auxiliary tube with the exterior surface thereof; and an end plug attached to a lower end of the auxiliary tube

[en] This cleanup verification package documents completion of remedial action for the 118-F-3, Minor Construction Burial Ground waste site. This site was an open field covered with cobbles, with no vegetation growing on the surface. The site received irradiated reactor parts that were removed during conversion of the 105-F Reactor from the Liquid 3X to the Ball 3X Project safety systems and received mostly vertical safety rod thimbles and step plugs

[en] A fluidic self-actuating control assembly for use in a reactor is described wherein no external control inputs are required to actuate (scram) the system. The assembly is constructed to scram upon sensing either a sudden depressurization of reactor inlet flow or a sudden increase in core neutron flux. A fluidic control system senses abnormal flow or neutron flux transients and actuates the system, whereupon assembly coolant flow reverses, forcing absorber balls into the reactor core region

[en] A shutdown system no. 1 (SDS1) with mechanical absorbing rods has been designed for an advanced CANDU nuclear reactor. The design addresses static neutronic properties and their verification when individual rods and entire rod system are fully inserted in the reactor core. The primary design started with the accommodation of the rods in a tight interval of the advanced lattice pitch. The shut-off rod design shape and elementary lattice neutronic properties were found out using the WIMS-PIJXYZ methodology. The WIMS-PIJXYZ methodology was developed in INR Pitesti and it is based on neutron transport equation solving in two and three dimensional geometries. A preliminary advanced DIREN core model has previously been developed and used to calculate the individual and entire SDS1 static reactivity. The comparison to a generic CANDU 6 SDS1 rods reactivities showed that the designed SDS1 is able to perform as well as the CANDU 6 SDS1 basic design does. (authors)

[en] A vertical control rod includes an absorber formed of flexible members and suspended by a traction device below the reactor core during operation of the reactor and a tensional spring for drawing the absorber into the reactor core to shut off the reactor. The control rod is operable independently of gravity and avoids jamming of the absorber in the guide

[en] Control is provided for short or part-length control rods used to govern power distribution within the reactor core, to prevent them from dropping to the bottom of the reactor upon loss of electricity. A spring-operated latch is fixed on the control rod support to positively mechanically lock the rod against movement in either direction. Two magnetically-actuated alternately-operating rod-moving members are preferably provided, each carrying its own independently-actuated latch or gripper mechanism for connecting the moving member with the rod or for disconnecting it. (LL)

No abstract available

[en] The control rod is surrounded by a tube, whose lower end is corrugated. The braking force acting on the control rod can be affected by the number of corrugated parts of the inner tube wall, by the angle and depth of the corrugations and possibly by smooth pieces of tube of suitable diameter. The internal diameter of the corrugated tube should preferably decrease from top to bottom. (DG) 891 HP/DG 892 CKA

[en] This patent describes, for use in facilitating replacement of a neutron absorber control rod on a control assembly spider structure, an end plug. It comprises a pair of separate upper and lower plug portions; the upper section of the upper plug portion being configured for rigid attachment; the middle section of the upper plug portion having angularly displaced flat surfaces formed on the exterior

[en] A new part length rod is provided which may be used to control xenon induced power oscillations but also to contribute to shutdown reactivity when a rapid shutdown of the reactor is required. The part length rod consists of a control rod with three regions. The lower control region is a longer weaker active portion separated from an upper stronger shorter poison section by an intermediate section which is a relative non-absorber of neutrons. The combination of the longer weaker control section with the upper high worth poison section permits the part length rod to be scrammed into the core. When a reactor shutdown is required but also permits the control rod to be used as a tool to control power distribution in both the axial and radial directions during normal operation