Program for Steam Purity Monitoring: 1. Instrumentation and Sampling

For the past 3 years the Westinghouse Electric Corp. has conducted a major program of instrument selection and development and sample analysis to monitor the steam turbine chemical environment and to determine the source of corrodant species that contribute to turbine blade corrosion.

This paper describes the development and application of a continuous on-line analyzer; a grab sample analysis program, utilizing state-of-the-art ion chromatography, to measure steam impurity concentration at various locations throughout the steam-water cycle; and the combination of these techniques, in the form of a total plant survey, to assess total power plant chemistry.

The significance and usefulness of continuously monitoring parameters such as sodium, dissolved oxygen, conductivities, and chloride is discussed, as are the validity of the sampling procedures, the utility of a nozzle to extract steam, and the strengths and weaknesses of ion chromatographic grab sample analyses. Finally, the implementation of a data acquisition system on the continuous analyzer, to handle the ever-increasing amount of information being generated by seven of these field systems, is reviewed.