Evaluation of secondary-system oxygen control in PWR power plants. Final report

The study discusses measures that should be incorporated into the balance of plant equipment in PWR plants to minimize oxygen content. It first reviews technical information about typical fossil and nuclear power plants in the USSR from the viewpoint of oxygen control. Next it addresses water conditioning in the condensate-feedwater system, including hydrazine-ammonia, chelate, and neutral modes, and variations of these modes. Reduction of oxygen ingress is discussed from the viewpoint of the condenser, feedwater heaters, moisture separator-reheater, and condensate storage tank. Emphasis is placed on proper condenser design and ejector operation. The importance of installing deaerating devices in the condenser itself and the feedwater system is discussed. Materials used in balance of plant equipment are analyzed for susceptibility to corrosion in the PWR plant environment. Recommendations are developed for protecting the system from oxygen contamination in different operating modes, particularly at startup and low load, and during shutdown. Suggestions for continuous monitoring and control of oxygen content in the condensate-feedwater system are included