Lance system for inter-tube inspecting and lancing as well as barrel spraying of heat transfer tubes of steam generator in nuclear power plant

Abstract

Disclosed is a lance system for inter-tube inspecting and lancing as well as barrel spraying of heat transfer tubes of a steam generator in a nuclear power plant, so that foreign substances piled up around heat transfer tubes in the steam generator are removed using high-pressure water. The lance system includes a rigid guide support rail positioned above a Blow Down Lane (BDL) at the center of the steam generator, a locomotion box including a motor drive unit for inducing a rectilinear motion of a lance body and a motor drive unit for inducing a rotational motion of the lance body centering on a horizontal axis, the lance body including a circular barrel including a motor drive unit for vertically erecting or horizontally laying down a multistage circular pole assembly, and a flat plate provided with linear passages for passing high-pressure water hoses, an optical cable and control rods therethrough, a circular drum assembly for stably connecting the high-pressure water hoses, the optical cable and the control rods, and the multistage circular pole assembly being extensible and contractible by the movement of the control rods obtained by engaging teeth of a toothed belt unit, driven by a motor and positioned in the circular barrel, with gear teeth of the control rods, and two nozzle blocks, for barrel spraying, provided with barrel spray nozzles fixedly assembled therewith, symmetrically fixed to the inner surface of the circular barrel, wherein the multistage circular pole assembly is vertically erected in the operation of inter-tube lancing and inspecting, in which the lance system approaches inner parts of the heat transfer tubes and sprays the high-pressure water thereto, and is maintained in a horizontally laid-down position in the operation of barrel spraying.