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Lead lithium alloy (Pb-17Li) is one of the candidate tritium breeders of fusion reactors. Lead bismuth eutectic alloy (LBE) is one of the candidate materials for the coolant of fast reactors and the target of accelerator driven systems. The functional layers such as an anti-corrosion layer and a tritium permeation barrier have been developed to be applied in these liquid metal systems. Zirconium oxide (ZrO2) are considered to be the candidate material of the functional layers due to its excellent chemical stability. The online monitoring of oxygen potential in the liquid metals is essential technology. The development of in-situ analysis technique for the layer properties in the liquid metals at high temperature is important issue. The purpose of the present study is to develop the on-line monitoring system for the oxygen potential and the layer properties both by the solid electrolyte (SE) oxygen sensor and the electrochemical impedance spectroscopy (EIS). The YSZ type SE sensor and the ZrO2/Zr specimen for the EIS were simultaneously immersed to liquid Pb at 698-898K. The responses of the oxygen sensor and the EIS were successfully obtained, and these signals indicated that the ZrO2 oxide layer is thermodynamically stable in liquid Pb. The EIS response was evaluated based on some equivalent circuit models as the oxide layer had a lot of horizontal cracks in its structure. The influence of the cracks on the capacitance is larger than that on the electrical resistance, when the covering ratio of the cracks in the layer is low. The influence on the electrical resistant becomes larger when the ratio is close to 100%.

We studied sound generated by a diagonally arranged fin in a uniform flow. We set 2-dimensional computational model which neglected spanwise effect of the fins, and performed direct simulation of aerodynamic sound for two types of fins whose difference is the width of the back section with the finite-difference lattice Boltzmann method. Conditions of numerical results in which strong resonance occurred consisted with experimental results and Parker type resonance appeared. When the resonance occurred, the frequency of Kármán vortex shedding from the trailing edges of the fins agreed with the natural frequency of air columns which correspond the space between neighbouring fins. The phase differences between the neighbouring columns were completely “anti-phase” and the same was true for the vortex shedding. We also show the temporal and spacial variations in far sound field which are caused by the asymmetric arrangement of the fins. We also noted that the radiations of sounds of two different frequency existed for high speed flow range.