With the aim of having management support for cycle chemistry program, many utilities have been performing EPRI benchmarking process, which assesses the benefit of cycle chemistry monetarily. Some utilities reported movement toward world class in cycle chemistry and reduction of the loss due to the cycle chemistry significantly. As improved cycle chemistry, AVT without N2H4 and equilibrium phosphate treatment were prevailed in U.S.A, etc..
Sulfur dioxide (SO2) is a typical gas affecting the atmospheric corrosion of metals, particularly outdoors. Although many studies have investigated the effect of SO2 on the atmospheric corrosion of silver and copper, little is known about the early stage of their corrosion behavior. In this study we analyzed the chemical state of sulfur on silver and copper plates exposed to flowing air containing low concentrations (18 and 148 ppb) of SO2 using X-ray photoelectron spectroscopy (XPS). The shapes of the spectra were the same for both concentrations, indicating that the chemical state of the analyzed elements did not depend on the SO2 concentration. There was a difference in the chemical state of the sulfur between the silver and copper. Three peaks were observed in the S 2p XPS spectra for the silver originating from bisulfite, S2O52-, S2O32-, and S2-. The bisulfite resulted from SO2 dissolution into the surface electrolyte, and the others resulted from the reduction of sulfurous acid. In contrast, only bisulfite was observed in the S 2p XPS spectra for the copper. It also originated from the dissolution of SO2 into the surface electrolyte. The difference in the chemical state of the sulfur between the silver and copper is attributed to the presence of native oxides on the surface, which may have impeded the reduction of bisulfite.
Effects of solution annealing condition, homogenizing, cold or hot rolling, aging, and the combination of cold rolling and aging were investigated on the corrosion resistance of Fe-18%Cr-14%Ni-0.5%Si-1.0%Mn alloys containing 100 ppm of C, P and S in concentrated boiling nitric acid. It was found that the corrosion resistance of Fe-18%Cr-14%Ni-0.5%Si-1.0%Mn alloys was remarkably degraded by the combined effect of 30% cold rolling and aging at 973 K, although neither cold rolling nor aging showed much influence on the corrosion resistance of the alloys. It was suggested that the degradation of corrosion property was induced by P segregation to grain boundaries of the alloys from the investigations into the micro-structural change and the impurity effect. It was also shown that Fe-18%Cr-14%Ni-0.5%Si-1.0%Mn alloys had superior corrosion resistance to SUS 304 L stainless steel in boiling 5 kmol/m3 nitric acid containing highly oxidizing ions.
Stress corrosion cracking (SCC) susceptibility of various solution annealed, non-sensitized, austenitic stainless steels was examined in high temperature water using creviced bent beam (CBB) and creviced uniaxial constant load (UCL) tests. The following results were obtained in this study. (1) 304, 304L, 316L, 316NG and 347NG were susceptible to SCC under the crevice and high applied stress conditions. (2) Deformation induced martensite is not necessary but accelerating factor for SCC in various solution annealed austenitic stainless steels. (3) CBB test and creviced UCL test give different results on the effect of cold work on the SCC susceptibility in various solution annealed austenitic stainless steels because of the difference in strain under their test conditions.