METHOD AND APPARATUS FOR REMOVAL OF RESIDUAL SLUDGE FROM A NUCLEAR STEAM GENERATOR

摘要

23 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.