Influence of synchrotron radiation on corrosion at the water—metal boundary

Abstract

Radiation damage due to synchrotron radiation has been studied at the boundary of cooling water and metal related to vacuum chambers: oxygen free copper (OFC). The damage was evaluated by measuring the dissolved ion concentration in water, sampled from the pure water circulating system with a sample pipe (10 mm in inner diameter and 1 mm in thickness), irradiated by synchrotron radiation with photons (40–700 keV) of the order of 10 16 photons (MeV mA s) -1 in the TRISTAN e +e - colliding ring (bending radius of 246 m and beam energy of 29 GeV). OFC with an irradiated surface area of 10 mm 2 showed a Cu ion concentration of 6 mg 1 -1 after 1.3 A h irradiation (800 h operation, 5.3 x 10 20 photons mm -2). The ion concentration showed an increasing rate of t 1 3 − 1 2 before 500 h. After 500 h operation, it was roughly proportional to t. The time dependence of the concentration of the non-irradiated sample was t 1 3 before 10 3 h. The concentration increased from 0.01 before 10 3 h to 1 mg l -1 after 10 3 h. The relationship between the free energy of formation and the estimated dissolved ion concentration of OFC together with the one of aluminum alloys, a 10 μm thick silicon dioxide film inside an Al pipe, and stainless steel 316L at 10 A h (the dose of the materials ranging from 4.1 to 5.8 x 10 21 photons mm -2) gives that the higher the free energy of formation, the lower the dissolved ion concentration. Therefore, to obtain a radiation resistant surface, the stable oxide (with higher free energy of formation) should be selected.