Apex Technologies, Inc.

Scott M Theiss

Bobby R Lawson

James E Brown, Jr

Gary R Muller

Sludge-removing fluid lances are moved simultaneously toward the center of a tube bundle in a steam generator through diametrically opposite lance ports. Fluid-blocking suction dams are placed in the peripheral lane of the steam generator at diametrically opposite inspection ports from which fluid-entrained sludge is removed. All four of the ports are spaced apart by 90.degree.. Fluid-entrained sludge is blocked on the opposite sides of both suction dams, thereby preventing redeposition of sludge in previously cleaned areas of the tube sheet of the generator. The fluid flow rates of the lances are controlled to be equal to each other, and the rate of removal of the fluid-entrained sludge through each suction dam is controlled to be the same as the fluid flow rate of each lance. A separate flushing stream in the peripheral lane is not required.

Nuclear steam generator sludge lancing method and apparatus

A method and apparatus for removing from the tube sheet and transfer tubes of a nuclear steam generator sludge deposits which occur from the use of all volatile treatment water chemistry. A continuously activated suction apparatus maintains at a low level the water/sludge inventory on the tube sheet. A high pressure first water lance is oscillated and stepped inwardly along the central tube lane of the generator to dislodge the sludge from the tube plate and heat exchange tubes. After this lance has been stepped inwardly to a predetermined position, a low pressure second water lance is activated and periodically advanced to a position just short of the first lance and functions both to dislodge sludge and to form a water barrier which prevents redeposition of sludge in the clean area. The flows from both lances combine to produce a high flow of water-suspended sludge which flows across the top of the tube sheet to the annulus of the steam generator where it is removed by the suction apparatus without any redeposition. Suction dams are placed in the vicinity of the suction apparatus in order to increase the efficiency of the removal of the water-entrained sludge by suction.

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Palm Harbor, FL, United States of America

Scott M Theiss