Characteristics of nano-sized TiO2 for an inhibitor of SCC

In nuclear power plants, steam generator (SG) tubes have certain characteristic features in their design to endure a severe problem, a stress corrosion cracking (SCC). Most SCCs have been occurred near the top of a sludge pile on a tubesheet and within a tube support plate crevice in which it is thought to be concentrated by ion impurities such as sodium which might cause a caustic and corrosive environment. Some inhibitors have been studied to reduce these SCC problems for SG tube materials. Laboratory tests using C-ring and constant extension rate specimens have shown that some chemical compounds may inhibit a SCC of the SG tube materials. Several titanium compounds have been tested for their application to certain types of PWR nuclear power plant.s SGs, such as Prairie Island 1 and 2, Point Beach 2, Callaway 1 etc. While, it has been reported that these are some beneficial effects, there is not enough evidence as yet that would convinced us of its positive effects as an inhibitor, and also, it has not been fully proven that Ti-compound can penetrate through a closed crevice or crack tip in a SG tube. The technology for the smallest scale in nature, nano-technology, has been advanced and has become an important branch in the current science. Many studies have reported on techniques for the production or fabrication of nano-particles and nano-structures. The sonochemical synthesis process was adapted in our study for the reason of its direct applicability to a liquid phase solution. Ultrasound in the liquid containing reactants causes a sonochemical reaction producing nano-particles. In this research we investigated an application of a sonochemistry technique to the TiO2 to reduce its particle size in order to improve its penetration property in a crevice of a SG and its performance on a SCC of the SG tube materials