Abstract: An improved robotic arm system for servicing the tubesheet located within the channel head of a nuclear steam generator is provided. The system includes a robotic arm whose shoulder and elbow joints are rotatable only in the plane parallel to the tubesheet in order to eliminate the imposition of cantileverly-induced torques on the electric motors driving these joints, as well as to minimize the possibility of mechanical interference between the arm and the walls of the channel head. Each of the motorized joint assemblies of the arm includes resolvers connected not only to the output of the drive train that moves the joint, but also to the drive shaft of the electric motor that drives the drive train, wherein the feedback signal generated by the resolver connected to the drive shaft of the electric motor is the primary signal used to modulate the amount of electric power conducted to the motor of the joint. Such a configuration advantageously results in smoother robotic arm movement.

Abstract: An eddy current probe, especially useful for inspecting roll plugs in steam generator tubes, has a detector assembly which is automatically extended and retracted in a radial recess in an elongated body to prevent damage to the detector assembly during insertion and retraction of the probe, yet permits the detector assembly to bear against the interior wall of the roll plug, including the roll zone. In one embodiment, a mechanical actuator in the form of a pair of finger members spring biased radially outward operate through camming surfaces to rotate a pivot member which retracts the detector assembly; however, when the probe enters the bore of a roll plug the fingers are compressed to permit extension of the detector assembly. In another embodiment, a linear actuator such as a solenoid rotates the pivot member to extend and retract the detector assembly.

Abstract: Apparatus and method for remotely decontaminating, cleaning, scrubbing or polishing the surface of a nuclear reactor cavity wall. The apparatus includes brushes for scrubbing the surface and a drive mechanism for rotating the brushes. The drive mechanism may be a gear drive, a chain and sprocket drive, or a belt and pulley drive. Connected to the brushes and enclosing the drive mechanism is an sealable enclosure. A drive axle extends from the drive mechanism to a motor which is disposed in a housing connected to and located proximate the enclosure. The motor is capable of rotating the drive axle which in turn operates the drive mechanism for rotating the brushes. A fluid dispenser is also provided for dispensing a cleaning agent against the surface to enhance the cleaning ability of the brushes. A container is attached to the housing for receiving ballast therein so that the brushes may exert a bearing pressure against the surface of the wall for suitably scrubbing the surface.

Abstract: Apparatus and method for dewatering radioactive waste slurry solids. The apparatus includes a vacuum pump for applying a vacuum to a suitable flexible filter and collapsible membrane combination in which the slurry solids are contained so that the slurry solids are compressively dewatered when the vacuum is applied. The apparatus further includes a container for suitably storing the resulting dewatered slurry solids.

Abstract: An improved apparatus for detecting radioactive contamination in garments. The apparatus includes a pair of radiation detectors spaced along a conveyor path. The conveyor system conveys the garments in a compressed condition and the garments are biased toward each of the detectors as they are conveyed therepast. A housing is provided with an air filtering system such that the conveyors are enclosed in a ventilated structure and the spread of contaminants accumulating within the housing is prevented. Preferably the conveyors include a thin, open grid arrangement which is strong, non-stick and includes an electrically conductive material which dissipates static charges. The detectors are gas-flow proportional and may be operated at a voltage optimized for sensing alpha particles. The detectors may also include plural zones some of which are operated at a voltage optimized for sensing alpha particles while others are operated at a voltage optimized for sensing beta particles.

Abstract: An apparatus and a method for remotely inspecting the interior walls of a cavity having a circular cross section that varies in diameter, such as the interior of a hollow tube plug. The apparatus has an eddy current probe head having a distal and proximal end, wherein the distal end engages the cavity walls, an elongated support assembly connected to the proximal end of the probe that is insertable within the cavity, a radial extender mechanism for radially extending and withdrawing the distal end of the probe with respect to the longitudinal axis of the support assembly, and a probe driving and delivery system for inserting the support assembly into the cavity and helically moving the probe head to inspect the cavity walls for discontinuities.

Abstract: A mounting system for removably mounting the lower flange of the control rod guide tube over an opening in the upper core plate of a nuclear reactor is disclosed. The system includes a pair of resilient pin members and a pair of reinforcing pin members. The resilient pin members are mounted in a passage formed through first opposing sides of the guide tube lower flange. They are resiliently receivable in first bores formed on first opposing sides of the upper core plate to permit deflection thereof when the guide tube is subject to normal shear loads. The resilient pin members bear substantially all of the normal shear load to which the guide tube is subjected. The reinforcing pin members are mounted on the second opposing side of the guide tube lower flange. They are receivable in second bores formed on the second opposing sides of the upper core plate with a clearance. The reinforcing pin members bear substantially all of the abnormal shear load that exceeds the normal shear load.