Among typical secondary system impurities, which group includes dissolved oxygen, sodium, chloride, pH, and corrosion products?

• A. Primary Water Chemistry
• B. Turbine Oils
• C. Feedwater Treatments
• D. Secondary System Impurities

Answer: (D)

The idea being tested is which set of impurities belongs to the steam/condensate and turbine side of the plant—the secondary system. Dissolved oxygen, sodium, chloride, and pH are all parameters that are monitored and controlled in this part of the cycle because they drive corrosion and affect heat-transfer surfaces. Oxygen promotes corrosion of steel and copper alloys; sodium and chlorides come from makeup water and potential contamination and can accelerate pitting and general corrosion; pH is adjusted to keep surfaces less susceptible to attack; corrosion products are the solids that form from ongoing corrosion and can circulate or foul equipment.

These items are not representative of the reactor coolant chemistry, which is the primary water side, nor are they simply the targets of feedwater treatment processes, nor related to turbine oils. So the proper grouping is secondary system impurities, since they are the impurities typically found and managed in the steam/condensate/turbine portion of the plant.