Steam Generator Primary Side Fouling Determination Using Oxiprobe Inspection Technique

Abstract

Build up of deposits on the primary side of CANDU steam generator tubes can lead to a loss of heat transfer between primary and secondary circuits. This fouling contains radionuclides that cause high radiation fields around the steam generators. It is important to determine the amount and nature of the deposits including radionuclides and their distribution in the tubes to assess the need for cleaning, selection of cleaning technologies, disposal of cleaning residues and other related maintenance issues. The Oxiprobe is an inspection technique developed by Ontario Hydro Technologies that measures the extent of primary side fouling at various positions along the length of a steam generator tube. Deposits are chemically removed from selected locations by means of tooling inserted from the primary head. Deposit loadings in each location can be quantitatively calculated and their elemental composition, which includes the determination of alpha, beta and gamma emitting radionuclides, can be determined.