Waterslap Cleaning of Support Plates

Abstract

In August, 1988, the waterslap process was identified as a temporary cleaning measure which may have application at the Ontario Hydro Bruce A generating station where SG#3 of Unit 2 was experiencing severe secondary side oscillations. The secondary side oscillations were attributed to severe deposition in the upper broach plate flow passages. The objective in using the process was to reduce the blockage enough to cause the oscillation to abate until more permanent measures could be developed. Waterslap is a process whereby the SG is filled with water to a level several inches below the support plate to be cleaned. Nitrogen gas is into the bottom of the SG bundle. The gas causes the water to move rapidly upward so as to slap the lower surface of the support plate. The cleaning effect results from the slap of the water on the support surface. A full scale system was designed and qualified for use at Bruce 'A' by the process designer. It was then built, subjected to test operation and finally deployed to site. The entire operation was completed by August, 1989. The paper describes the design qualification testing and operation of the process.