Electric Power Research Institute Incorporated

Thomas O Passell

John W Berthold

Palitha Jayaweera

Peter J Millett

Michel N Robles

Garry W Roman

James Leon Simpson

Constantine N Spalaris

An autoclave-enclosed sidestream model boiler is used to predict the onset of intergranular attack ('IGA') and stress corrosion cracking ('SCC') within tubing associated with a power generator. Power generator final feed water is fluid coupled to a pipe within the model boiler, which pipe is strain-gage monitored, preferably using welded fiber optic strain gage devices. The monitored pipe includes a crevice region that produces a water-starved region in which chemical impurities in the feed water become concentrated. A cylindrical heater, located within a portion of the monitored pipe, promotes the water-starved region. A cylindrical portion of the pipe wall preferably is thinned, generally in the region bounding the crevice. Thinning promotes the onset of IGA/SCC within the monitored pipe and also passively amplifies the effects of IGA/SCC to promote easier strain detection. To further promote stress, the monitored pipe is subjected to loading and unloading from an axial load. Drift in the strain gage measurement can be substantially eliminated by taking measurements under axial load and no load conditions, as these two conditions may be attained within a short time of each other, e.g., a few minutes. Long term monitoring of the strain gages provides a measure of onset and progression of IGA and SCC within the autoclave model. These measurements can provide a prediction of the onset of IGA and SCC within the actual power generator, allowing corrective action to be taken before a pipe fails.

Method and apparatus for predicting onset of intergranular attack and

A solid state reference electrode which is stable over a wide range of temperatures, pressures and chemical conditions is provided. The subject reference electrode comprises a zirconia or yttria stabilized zirconia tube having a distal, closed end and a proximal, open end. An opening in the distal end of the tube provides for ionic conduction between the electrolyte inside of the tube and fluid outside of the tube. Inside the tube is an electrolyte containing zirconia, alumina, potassium chloride and silica. Positioned in the electrolyte composition, near the proximal end of the zirconia tube, is a sensing element. A sealing means at the proximal end of the tube seals the inside of the tube and connects the tube to a stainless steel casing. An electrical lead extends from the sensing element through the sealing means. The electrode comprises means for maintaining a constant temperature in the region of the electrolyte composition occupied by the sensing element.

Solid state reference electrode for high temperature electrochemical

An on-line and continuous sampling system for monitoring the ionic content of steam-producing water in a steam-operated electrical power plant. The monitoring system comprises a plurality of sampling lines and associated apparatus for sampling the steam-producing water at a number of different points in the power plant, an ion chromatographic subsystem for analyzing the sampled water, a calibration subsystem for calibrating the ion chromatographic subsystem, and an automatic control subsystem for operating the monitoring system of the present invention.

System for continuously monitoring the ionic content of steam-producing

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Palo Alto, CA, United States of America

Thomas O Passell