Nuclear power plants stress-corrosion cracking

The total cost of material fracture is about 4% of gross domestic product in the United States and Europe (88,89). Fracture modes included in the cost estimates were stress-induced failures (tension, compression, flexure, and shear), overload, deformation, and time-dependent modes, such as fatigue, creep, SCC, and embrittlement. The environmentally assisted corrosion problem is very much involved in the maintenance of the safety and reliability of potentially dangerous engineering systems, such as nuclear power plants, fossil fuel power plants, oil and gas pipelines, oil production platforms, aircraft and aerospace technologies, chemical plants, and so on. Losses because of environmentally assisted cracking (EAC) of materials amount to many billions of dollars annually and is on the increase globally (87). 

An example is the SCC of stainless steel at 200 °C in a caustic solution or in aerated chloride solution where no traces of dissolution are visible on the crack face. The three conditions, namely, tensile stress, susceptible sample material, and a corrosive environment are the conditions necessary for stress corrosion to take place (73, 90). For instance, SCC of metals has been by far the most prevalent cause of failure of steam generator components in pressurized water reactors (PWRs) to an extent of 69% of all cases, piping in boiling water reactors (59.7%) and PWRs (23.7%). More than 60% of inspected steam turbines in nuclear power plants have disks with stress corrosion cracks (91). 

J. Jacobs and G. P. Wozadlo, Irradiation Assisted Stress Corrosion Cracking as a Factor in Nuclear Power Plant Aging, Paper presented at the July 8-10, 1985 International Conference on Nuclear Power Plant Aging, Availability Factor and Reliability Analysis, and published in conference proceedings, p. 173, dated August 1985, American Society for Metals, Metals Park OH 44073. 

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