Development of the Pacific Nuclear High Temperature Steam Generator Cleaning Process

Abstract

Processes to clean the secondary side of steam generators have evolved considerably since the early development studies on the Indian Point-1 PWR. An industry-wide effort, sponsored by the EPRI Steam Generator Owners Group (SGOG), led to the well-known SGOG solvents for cleaning the deposits from the tube sheet and from within crevices. Later developments, funded by the process vendors, have produced high temperature cleaning processes. These processes are particularly attractive when cleaning the full height of the steam generator or a substantial level up the steam generator tubes. In this paper, the development of the Pacific Nuclear High Temperature (PNHT) Steam Generator Chemical Cleaning Process is reviewed. It is a logical extension of the well-qualified SGOG processes and is based on the use of the same chelating agent (EDTA) and corrosion inhibitor (CCI-801). The relative merits of high temperature processes are compared with those of the lower temperature processes. Different circumstances make different types of process the preferred option. These circumstances are discussed.