Waterlancing for CANDU Steam Generators

Abstract

Sludge removal from steam generators is now considered essential in minimizing the risk of tube corrosion due to attack within the sludge deposits and waterlancing has gained wide acceptance as the preferred method for removal of sludge from tube sheets. Waterlancing has recently been performed as a demonstration project at Pickering Unit 1 Steam Generator (SG) No. 3 - a unit with very difficult access and very hard sludge. The equipment setup involved specially designed, compact, articulated lances for use with the existing system. The results showed that this type of unit could be lanced, but at a slow rate due to the hardness of the deposits. It also showed that tube erosion was not a problem. Based on this experience and its widespread acceptance, waterlancing at regular intervals is recommended.