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Hanawa, Satoshi; Hata, Kuniki; Chimi, Yasuhiro; Nishiyama, Yutaka
Proceedings of Symposium on Water Chemistry and Corrosion in Nuclear Power Plants in Asia 2013 (USB Flash Drive), 7 Pages, 2013/10
Water chemistry experiments will be carried out by using an in-pile loop newly installed in the JMTR. Concentrations of chemical species of O, H and HO are measured at the inlet and the outlet of the irradiation field. Electrochemical corrosion potential (ECP) at the irradiation field is also monitored. These experimental data will be obtained under wide range of experimental conditions such as absorption dose rate, H or O concentration in the feeding water and water temperature. As a result of preliminary calculations, it became clear that the in-pile loop in the JMTR is capable for water chemistry experiment. Although the operation of the JMTR is being delayed because of the Tohoku district off the Pacific Ocean earthquake, construction of the loops and installation of the instrumentation for the loops have been carried out almost on schedule. The experiments will be started after JMTR restart.
Sato, Tomonori; Kato, Chiaki; Ogi, Hirokazu*; Yamamoto, Masahiro; Ueno, Fumiyoshi
Proceedings of Symposium on Water Chemistry and Corrosion in Nuclear Power Plants in Asia 2013 (USB Flash Drive), 6 Pages, 2013/10
The hydrogen peroxide (HO) generated by the water radiolysis in the reactor coolant under irradiated condition plays an important role for the stress corrosion cracking (SCC) in the boiling water reactors (BWRs). In this study, the corrosive condition in high temperature water containing HO was observed directly utilizing electrochemical impedance spectroscopy (EIS) in high temperature pure water. And the diffusion coefficient and thermal decomposition rate of HO at the 288 C were estimated based on the obtained impedance responses. The reciprocal of the polarization resistance has linear relationship to the HO concentration. The estimated diffusion coefficient of HO (D) was 1.510 cm/s when the thickness of the diffusion layer was assumed to be 0.05 cm. The thermal decomposition rate of HO in 288C was 0.042 s.