Abstract: A nuclear reactor having an upper internals control rod assembly guide tube formed from upper and lower sections that are connected along a central axial region of the guide tube at an intermediate coupling. An extended control rod axial support is provided for at least some of the control rods over a finite distance within at least one of the interiors of the lower guide tube section or the upper guide tube section.

Abstract: Systems and methods for providing override control for a feedwater pump recirculation valve are provided. According to one embodiment, a system may include a controller and a processor communicatively coupled to the controller. The processor may be configured to receive one or more measurements associated with pump motor power driving feedwater pump flow. The feedwater pump recirculation valve may be configured to maintain a predetermined minimum recirculation flow through the feedwater pump by regulating recirculation pump flow through a recirculation line. The processor may be also configured to calculate, based at least in part on the one or more measurements, the recirculation pump flow, and compare the recirculation pump flow to the predetermined minimum recirculation flow. Based at least in part on the comparing, the processor may selectively provide an override control signal to the feedwater pump recirculation valve to selectively modify the recirculation pump flow.

Abstract: A method for controlling the positions of a plurality of nuclear fuel assemblies (1) relative to an upper core plate (3) in a nuclear reactor core, the method including the following steps: choosing a reference point (13) in internals or in a reactor vessel; determining the positions of S-shaped holes of the nuclear fuel assemblies (1) relative to the reference point (13), each S-shaped hole being intended to cooperate with a corresponding centering pin of the upper core plate (3); acquiring the positions of the centering pins of the upper core plate (3) relative to the reference point (13); and comparing the positions of the S-shaped holes and the positions of the pins and deducing therefrom whether the nuclear fuel assemblies (1) are correctly positioned relative to the upper core plate (3).

Abstract: A tool for delivery of a testing element to a limited access location within a nuclear containment includes a rotation apparatus having a connection element that is configured to have an aperture that is formed generally centrally therein. A submersible machine is structured to carry the tool to a limited access location within a nuclear containment. The submersible machine includes a mount apparatus configured to be movably clamped onto a steam dam of a nuclear reactor apparatus and to drive the submersible machine circumferentially along the steam dam to inspect a plurality of jet pumps or other limited access locations of the nuclear reactor apparatus. The improved submersible machine advantageously further includes an adjustment table between the mount apparatus and a frame that carries the tool to enable rapid accurate positioning of the frame, and thus the tool, once the submersible machine has been mounted to the steam dam.

Abstract: A continuous alpha monitor includes an air intake mechanism, which in turn includes an air mover, an air intake prefilter that limits particulates in the air intake mechanism to an aerodynamic diameter of 10 microns or less, and a particle detector mounted downstream of the air intake prefilter, the air particle detector providing a first airborne dust concentration and a first distribution of aerodynamic diameters of particulates in air passing the prefilter, the particulates including depleted uranium particulates. The monitor further includes a movable sample filter web that collects the particulates; a solid state detector that detects alpha radiation emitted by the collected particulates; a processor that executes machine instructions embodied on a non-transient computer-readable storage medium to compute a dust loading on the sample filter web; and the processor computes an indication of alpha concentration detected by the solid state detector.

Abstract: A method and apparatus for inspecting the upper portion of a core shroud of a nuclear power plant is provided. The upper shroud scanner mounts on an arcuic section of a steam dam of the core shroud and moves back and forth there along. A vertical arm with transducers thereon extend down from a Y-car portion of the upper shroud scanner. Transducers adjacent the core shroud emit and receive an ultrasonic sound to inspect for flaws and defects in the core shroud.