Occupational exposure due to steam generator repair

Steam generators at several nuclear power plants have experienced corrosion problems which require inspection and maintenance of the steam generator tubes to ensure continued safe operations. This inspection and maintenance leads to high radiation exposure of plant personnel. The radiation hazard is created by corrosion products deposited on reactor components and systems. In order to eliminate or reduce this problem, it has been proposed that the steam generator lower assemblies be removed and replaced. This removal and replacement can itself lead to significant radiation exposure. An estimate of radiation exposure to occupational personnel was calculated using time and personnel involvement estimates. Exposure rates were derived from data gathered at four operating nuclear power plants. Man-rem estimates were made for each job during removal and replacement, and then totaled for the entire operation. Potential quantities of liquid and airborne effluents were also calculated. Various options for steam generator disposal were evaluated from a radiation exposure standpoint. (author)