Abstract: Briefly, the range limiting system of the invention is capable of differentiating desired received signals having an amplitude above a predetermined threshold level and at least one other recognizable predetermined characteristic, from other received signals below that predetermined threshold amplitude. The system has a means for combining the received signal, which is of unknown amplitude which may be above or below the predetermined threshold amplitude, with a known signal of the predetermined threshold amplitude having at least one other predetermined characteristic which is distinguishable from the other recognizable characteristic of the received signal. The output of the combining means passes to a signal processing means which produces an output signal whose other recognizable characteristic is determined by the received signal only when the received signal is above the predetermined threshold amplitude, and by the known signal when the received signal is below the predetermined threshold amplitude.

Abstract: The invention provides a system for discriminating between modulated backscattered signals based upon transmission-to-reception time delay. The system employs a carrier, phase-modulated with a modulating signal, having characteristics which provide unity output when correlated with itself with zero time shift and a substantially lower output level when correlated with itself with a significant time shift. The system works with a backscatter-modulator located a finite distance from the transmitter for receiving and modulating the backscatter of the carrier. A receiver/detector receives and detects the modulated backscattered phase-modulated signal, the detector being phase-sensitive and having as a reference signal the transmitted phase-modulating carrier signal, and having as an input signal the phase modulated backscattered carrier.

Abstract: A sludge lancing method comprises providing a lancing nozzle and a barrier nozzle for respectively emitting cleaning and barrier streams of fluid along two channels between columns of heat exchange tubes in a nuclear steam generator vessel, the two channels being spaced apart by at least two columns of tubes. The barrier stream prevents dislodged sludge from being moved laterally past it into previously cleaned areas. The streams may be rotated between the center and the periphery of the tube sheet. The barrier nozzle comprises three jets angularly disposed with respect to one another for increased coverage of the barrier channel.

Abstract: A sludge lance nozzle for removing sludge from between the tubes of a nuclear steam generator includes positioning apparatus mounted on top of the nozzle. The tubes are arranged in rows and columns with the axes of the tubes in each column lying in a common column plane. The nozzle is moved perpendicular to the column planes close to one of the rows of tubes. In one embodiment, the positioning apparatus comprises two transmitter/receivers for transmitting signals and receiving reflected signals along axes parallel to the column planes, the axes being spaced apart by odd multiples of one-half tube pitch. The received signals are subtracted to produce a position indicating signal. In another embodiment the positioning apparatus includes a transmitter and a receiver spaced apart in the direction of movement of the nozzle, the transmitter transmitting a signal in a first predetermined direction, and the receiver being responsive only to reflected signals received from a second predetermined direction.

Abstract: The invention comprises methods and apparatus for conducting a stream of electrolyte solution with an electrical potential applied between the nozzle of the apparatus and the piece of equipment to be decontaminated. The apparatus provides a nozzle that is capable of conducting the electrolyte to the component to be decontaminated in an effective manner without short circuiting the electrical system. Moreover, the method provides a means by which the exposure time of the component to the electrolyte is controlled such that corrosion of the component is minimized while the component is effectively decontaminated.