The cost of corrosion-related failures in nuclear power plants (NPPs) is significant. In pressurized water reactors, deposit fouling in the secondary system can cause undesired consequences. Studies show that the addition of polyacrylic acid (PAA) to the steam generator water increases the corrosion resistance of steel and promotes removal of iron-based deposits from surfaces. Since 2009, PAA has been used at several NPPs as a dispersant in the feed water. These NPPs need to accurately measure PAA to ensure that the added amount is within the plant's administrative limits. The NPPs also need to determine trace concentrations of ionic impurities, which are critical for the identification and prevention of corrosive conditions in power plant components. The feed water in the secondary system contains other corrosion inhibitors (e.g., ethanolamine [ETA]) to obtain an alkaline pH and a volatile oxygen scavenger (e,g., hydrazine) to form protective magnetite on the surfaces of the steam generator components. We present a size exclusion chromatography method to determine low (< 20 �g/L) concentrations of PAA and an ion chromatography method to determine trace concentrations of fluoride, chloride, and sulfate in secondary feed water samples containing PAA, ETA and hydrazine. PAA is resolved from the matrix on a polymer-based size-exclusion column using water as the eluent, and detected at 200 nm with a detection limit of ~2.6 �g/L. The trace anions are extracted onto a concentrator column while the sample matrix is diverted to waste. The anions are then separated on an anion-exchange column using isocratic elution with electrolytically generated potassium hydroxide and detected by suppressed conductivity. The recovery of spiked PAA and anions of interest in the secondary feed water and simulated secondary feed water are in the range of 99.5-109% and 92.3-101%, respectively.

Determination of polyacrylic acid and trace anions in nuclear power plant pressurized water reactors

247th National Meeting (2014)

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