[en] In September 1992, interim secondary water chemistry recommendations for IGA/SCC control in recirculating steam generators (RSGs) were issued by EPRI. The provisions of these recommendations were incorporated into Revision 3 of the PWR Secondary Water Guidelines in 1993. These guidelines address the significant increase in observations of tube support region IGA/SCC in RSGs with mill annealed Alloy 600 tubing and drilled hole support plates in recent years. Of particular concern was the fact that such attack was frequently occurring at plants that operated well below impurity concentration limits established in Revision 2 of the PWR water chemistry guidelines, i.e., blowdown impurity concentrations generally were maintained below 5 ppb. Since it was clear that operating even at very low blowdown impurity concentrations would not assure the absence of significant steam generator tubing corrosion, the Revision 3 guidelines recommend the following additional actions: (1) Increase the feedwater hydrazine concentration to > 100 ppb during normal operation to decrease the quantity of oxidants entering the steam generators and provide better assurance that reducing conditions are maintained in the steam generators. (2) Decrease the feedwater iron concentration limit to 5 ppb to reduce the tendency for sludge buildup, crevice plugging and tube fouling. (3) Continue or consider the use of boric acid. (4) Consider establishing the ''cation to anion ratio'' in the blowdown as a diagnostic parameter and attempt to operate at a site specific value to maintain a neutral to slightly acidic crevice solution pH where it is expected that IGSCC will be minimized. (5) Perform routine hideout return evaluations and employ these data to adjust the cation to anion ratio during normal operation. In this paper, approaches taken to modify crevice chemistry, i.e., establish a near neutral solution chemistry where minimum IGSCC is anticipated, are summarized for three U.S. PWRs. (authors). 10 figs., 3 refs

[en] Under EPRI sponsorship, an industry committee, similar in form and operation to other guideline committees, was created to develop Condensate Polishing Guidelines for both PWR and BWR systems. The committee reviewed the available utility and water treatment industry experience on system design and performance and incorporated operational and state-of-the-art information into document. These guidelines help utilities to optimize present condensate polisher designs as well as be a resource for retrofits or new construction. These guidelines present information that has not previously been presented in any consensus industry document. The committee generated guidelines that cover both deep bed and powdered resin systems as an integral part of the chemistry of PWR and BWR plants. The guidelines are separated into sections that deal with the basis for condensate polishing, system design, resin design and application, data management and performance and management responsibilities

[en] An effective, state-of-the art secondary water chemistry control program is essential to maximize the availability and operating life of major PWR components. Furthermore, the costs related to maintaining secondary water chemistry will likely be less than the repair or replacement of steam generators or large turbine rotors, with resulting outages taken into account. The revised PWR secondary water chemistry guidelines in this report represent the latest field and laboratory data on steam generator corrosion phenomena. This document supersedes Interim PWR Secondary Water Chemistry Recommendations for IGA/SCC Control (EPRI report TR-101230) as well as PWR Secondary Water Chemistry Guidelines--Revision 2 (NP-6239)