Contents Issue 4 (2001)

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Stephen E. Ziemniak

Solubility Behavior and Phase Stability of Transition Metal Oxides in Alkaline Hydrothermal Environments

The solubility behavior of transition metal oxides in high temperature water is interpreted by recognizing three types of chemical reaction equilibria: metal oxide hydration/dehydration, metal oxide dissolution and metal ion hydroxocomplex formation. The equilibria are quantified using thermodynamic concepts and the thermochemical properties of the metal oxides/ions representative of the most common constituents of construction metal alloys are summarized on the basis of metal oxide solubility studies conducted in our laboratory. Particular attention is devoted to the uncharged metal ion hydroxocomplex, Mz(OH)z (aq), since its thermochemical properties define minimum solubilities of the metal oxide at a given temperature. Experimentally-extracted values of standard partial molal entropy (S°) for the transition metal ion neutral hydroxocomplex are shown to be influenced by ligand field stabilization energies and complex symmetry.
PowerPlant Chemistry 2001, 3 (4)

James A. Mathews

Cost of Chemical Excursions

The economic risk of chemistry excursions has a significant impact in the highly cost volatile electric energy market. The cost of chemistry excursions is centered in the probabilistic risk and potential exposure of these assets. Chemistry excursion costs cannot be a statistical average of long-term projections as are used in making decisions regarding capital asset improvements. Scientific data provide information on the consequence of variance in operating chemistry parameters. Benchmarking actual events provides the opportunity to examine the statistical costs of chemistry excursions on a real-time basis.
Chemistry upsets are demonstrated to cost millions of dollars for each event. These costs are realized in both short-term and long-term losses. Because of the subtle and sometimes benign conditions of minor chronic chemistry excursions, their long-term costs will exceed the cost of short-term catastrophic chemistry excursions.

PowerPlant Chemistry 2001, 3 (4)

Francis Nordmann, Michel Dijoux and Agnès Stutzmann

EdF Approach for Fouling Mitigation

This paper describes the fouling of steam generator tubing in the 58 French PWR units, and the different studies and actions carried out to try to solve the problem and avoid any power output reduction associated with pressure drop. The remedies include the selection of the best secondary water treatment with amines such as morpholine in order to minimize corrosion product transport as well as mechanical remedies such as sludge lancing or chemical cleaning. Other options like dispersant addition are under evaluation.

PowerPlant Chemistry 2001, 3 (4)

Eskom International Conference on Power Plant Chemistry and Process Water Treatment

The Eskom International Conference on Power Plant Chemistry and Process Water Treatment took place in Midrand, South Africa, on April 3-5, 2001. This contribution lists short abstracts of all thirty-six papers presented at this important international conference.
PowerPlant Chemistry has been given permission to publish selected papers from the conference.

PowerPlant Chemistry 2001, 3 (4)

Neil B. Caris

On-Line Condensate Polishing Plant Resin Kinetic Challenge

Koeberg Nuclear Power Station is a twin 920 MW Westinghouse design, French-built PWR situated near Cape Town on South Africa’s west coast. The plant is seawater cooled with a double-walled, titanium-tubed condenser. The condenser design is of the divided hotwell type to accommodate sidestream full-flow condensate polishing in the event of a condenser tube leak.
The condensate polishing plant (CPP) resin at Koeberg has been in use since each unit was commissioned (approximately 16 to 17 years). The expected life span of this resin, based on a cation/mixed bed configuration at a condensate temperature of approximately 30 °C, is between 10 and 12 years.
Chemistry performed on-line kinetic challenges of the mixed bed resin to evaluate its condition by injecting seawater solutions at various concentrations at the suction side of one of the CPP charging pumps during a shutdown for outage.

PowerPlant Chemistry 2001, 3 (4)

Stéphanie Marais

Industrial-Scale Electrochemical Reactor for Flocculant Production

The electrochemical generation of ferric ions offers a viable alternative to conventional flocculants. An industrial-scale electrochemical reactor unit was designed, constructed and evaluated on various types of waters for the production of a flocculant. The technology has several features. The electrochemical reactor unit is compact and easy to incorporate into an existing system. No expensive reagents are required. The efficiency of the process is high. High concentrations of the flocculant can be obtained with limited energy consumption. The electrochemically-generated flocculant has similar properties to conventional flocculants such as ferric chloride. The electrochemical reactor generates a flocculant that is free of detrimental associated anions such as chlorides and sulfates. Preliminary cost calculations reflect an operational cost saving of 45% when using electrochemical flocculant production as opposed to conventional flocculants. The process is technologically simple, ecologically sound, and economically viable.
PowerPlant Chemistry 2001, 3 (4)