Nucleation of two types can occur in the water-steam flowing in a nozzle or in a turbine: homogeneous (spontaneous) and heterogeneous. The effects of chemistry on the flowing steam nucleation and condensation are not quite explained. An approach is used in the paper which is based on binary nucleation of the main impurity NaCl and water. Physical and mathematical models are mentioned and are applied on the steam flow with condensation in a convergent-divergent nozzle. A binary nucleation numerical model is applied for the calculation of the flow with condensation in the nozzle with a low expansion rate in the divergent nozzle part P = 1000 s^–1. Calculation results of pressure distribution are compared with experiments. The agreement between calculations and experiments is very good. The homogeneous nucleation and condensation of pure water-steam in the same nozzle is also calculated. The results are discussed. The main features of the binary nucleation and condensation of water and NaCl and of the homogeneous nucleation of pure water are compared.

Graver Technologies developed and commercialized an ultra-low chloride strongly basic anion resin for condensate polishing applications. Multiple lots of this new resin were installed in a nuclear plant in the United States. The ultra-low chloride resin allowed this plant to increase their amine concentration and consequently to reduce iron transport.

Work is underway to develop a corresponding ultra-low sulfate strongly acidic cation resin for condensate polishing applications. The development study involves post-treatment of a number of commercially available strongly acidic cation resins under comparable, strictly controlled conditions. Sulfate leachables and total oxidizable carbon (TOC) measurements during and after the post-treatment operations serve as metrics for this project.

Steam turbines in boiling water reactor (BWR) and pressurized water reactor (PWR) power plants of various manufacturers have been affected by corrosion fatigue and stress corrosion cracking. Steam chemistry has not been a prime focus for related research because the water in nuclear steam generating systems is considered to be of high purity. Steam turbine chemistry however addresses more the problems encountered in fossil fired power plants on all volatile treatment, where corrosive environments can be formed in zones where wet steam is re-evaporated and dries out, or in the phase transition zone, where superheated steam starts to condense in the low-pressure (LP) turbine. In BWR plants the situation is aggravated by the fact that no alkalizing agents are used in the cycle, thus making any anionic impurity immediately acidic. This is illustrated by case studies of pitting corrosion of a 12 % Cr steel gland seal and of flow-oriented corrosion attack on LP turbine blades in the phase transition zone. In PWR plants, volatile alkalizing agents are used that provide some buffering of acidic impurities, but they also produce anionic decomposition products.

This paper presents a new set-up with an expansion chamber for the experimental prediction of the size and concentration of heterogeneous impurities occurring in the steam transition zone. The onset of steam droplet nucleation on existing heterogeneous impurities is realized by controlled pressure decrease in the test section – the expansion rate. As a result these nuclei increase to the measurable values. The method for the prediction of the size and concentration of droplets is based on measuring the light attenuation of monochromatic light at two of the light wavelengths. Then the initial size and concentration of the seeds are determined using the heterogeneous condensation model to obtain the best fit of the calculated and measured light transmittances. The tests were carried out both in the laboratory at the Czech Technical University in Prague and in the power station Pocerady (200 MW LP steam turbine).

The use of condensate polishing by the Electricity Supply Board (ESB) of Ireland dates back to 1969. The designs and procedures used have evolved and improved over the years as experience has been gained. The ESB were, in 1980, the first utility to adopt an innovative high efficiency resin separation/regeneration procedure and also developed a simple yet effective procedure for operating in the economical ammonium form. Based on their experience they consider that the use of condensate polishing makes a significant contribution to reducing corrosion and so continue to apply it on new power stations.

This paper is a brief report about the Water Chemistry Forum, an event that took place in Moscow, Russia, in April 2008. One hundred fourteen participants attended more than 40 scientific and technical presentations reflecting the major topics of interest in the Russian power industry.

In the February 2008 issue, we introduced our project PPChem 101 "Fossil Cycle Chemistry" with the first lesson (What Is Plant Cycle Chemistry and Why Is It Important for Steam and Power Generating Plants?). In March the second lesson (Makeup Water Treatment), in April the third lesson (Cycle and Component Design, Materials, Operating Mode, and Plant Cycle Chemistry), in May the fourth lesson (Feedwater Treatment) followed, in June the fifth lesson (All-volatile Treatment), in July the sixth Lesson (Oxygenated Treatment), and in August the seventh Lesson (Feedwater Treatment with Organic Chemicals). The focus of this lesson is on the boiler water treatment.