This paper provides a review of the latest analytical methods that are being explored for predicting the failure probability for low pressure steam turbine discs and blades. Two deterministic methods are explored. The first method is Damage Function Analysis (DFA), which posits that damage can be described in terms of a damage function (DF) for a large ensemble of events (pits and/or cracks), and which provides a measure of the total damage (area under the DF) and of the time at which the deepest event exceeds in length the critical dimension. However, in many situations, the population of pits is not sufficiently large to effectively define the damage function and systems often fail by a single event. In these cases, failure is better described by a Monte Carlo method that retains the deterministic nature of the nucleation, growth, and death of individual events, but in which the sites of pit nucleation are statistically distributed and in which the fate of, and interaction between, individual pits may be followed in detail. The two approaches yield the same results if a sufficiently large ensemble is available, but the "deterministic" Monte Carlo method has significant advantages in describing the repassivation of events and in accounting for failure in terms of "rare events". DFA and the Monte Carlo method are used in this paper to calculate the failure probability of low pressure turbine discs in terms of the concentrations of oxygen and chloride ion in, and the pH of, the thin electrolyte film that exists on turbine surfaces upon shutdown over 219 cycles, each of 600 h duration (100 h shutdown, 500 h operating). These modeling studies suggest practical strategies for decreasing the probability of turbine blade and disc failure due to stress corrosion cracking and corrosion fatigue.

GE Water & Process Technologies (GE) developed a new organic-based mild steel corrosion inhibitor for use in closed recirculating cooling systems to effectively replace benchmark molybdate/nitrite treatments. Laboratory data comparing the corrosion inhibition obtained with the new product with the benchmark and with other organic mild steel inhibitors used for closed cooling loops are presented. The corrosion inhibition efficacy in the laboratory was established by standard electrochemical tests, linear polarization, and under heat transfer conditions with an apparatus that simulates a closed loop recirculating system. In the apparatus corrosion is monitored by coupon weight loss measurement, corrosion rate meters, and the visual appearance of a heat exchanger tube.
Hypothetical mechanisms by which the new product inhibits corrosion of mild steel are also discussed.

Under work sponsored by the Electric Power Research Institute (EPRI), the concept of a portable resin tester device for assessment of resin kinetics and other properties was envisioned. Ensuing work included design of the instrument and fabrication of a prototype version. Initial testing of the EPRI Resin Tester was performed at the LabComp, Inc. manufacturing facility in California and the FirstEnergy Corp. Bruce Mansfield Plant in Pennsylvania. These tests demonstrated both the simplicity of instrument operation and the feasibility of using the resin tester for rapidly determining anion and/or cation exchange kinetics. The tests also provided recommendations for optimizing instrument design and operation. Additional field tests at the Bruce Mansfield Plant were performed to determine the exchange kinetics of condensate polisher resin collected from a number of company plants and to compare resin tester results with plant performance results. This paper reports on the outcome of the field tests and discusses the correlation between laboratory analyses and the field trial results.

Legionella, known to be the causative agent of Legionnaires' disease, is a wide-spread bacteria occurring naturally in water. Favorable growing conditions in man-made systems can lead to massive growth and thus to a considerable risk for human beings. Evaporative cooling towers provide good living conditions due to their operational conditions. As a consequence, the growth of Legionella in these systems has to be controlled. Amongst other measures biocides are dosed to control the growth of the microbiological population and thus the possible risk of an infection by Legionellae. However, Legionella preferably lives in biofilms and/or amoebae, which strongly shelter this microbe. Furthermore, amoebae by themselves can be harmful to humans as well. Therefore, a biocide treatment should control Legionella (planktonic in water and in biofilms/amoebae) as well as the amoebae. This paper shows that an adapted biocide treatment can increase the efficiency of a biocide against Legionellae and amoebae und therefore minimize the risk of an infection by Legionella.

In order to evaluate the influence of chloride, sulfate and carbon dioxide in water on the electrochemical corrosion behavior of geothermal steam turbine materials, measurements of the anodic polarization and the pitting corrosion potential were conducted in simulated geothermal waters.
The corrosion resistance of all materials tested was lowered by an increasing carbon dioxide content in the simulated geothermal waters. Higher chloride concentrations in the waters induced lower corrosion resistance and also lower pitting corrosion potentials for materials with higher chromium contents, suggesting the corrosion behavior was mainly controlled by the chromium content of the materials. The corrosion resistance of 9CrMoV and 13Cr steels was also influenced by the concentration of sulfate in the water. The improved heat-treated 16Cr-4Ni material for turbine blades showed excellent corrosion resistance. In the presence of sulfate, the corrosion reactions are mitigated due to a decreasing concentration of chloride (due to the presence of sulfate) in corrosion pits.

In an industrial power station with several natural circulation boilers (permissible operation pressure 13.6 MPa), raw water treatment via demineralization, condensate polishing and thermal feedwater degasification, the cycle chemistry was changed from hydrazine/phosphate to amine/polyamine treatment.

The modification was supervised by TÜV SÜD with several water chemical analyses of the water/steam circuit. No problematic water conditions were found during the investigations. Fewer condensate impurities and a reduced amount of boiler blowdown can be stated as positive results of the transition to the polyamine treatment.