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[en] The conventional nondestructive testing has been performed in those area which are susceptible to thermal stress in according to NRC 88-08,11. In addition to that, it is necessary to set up a monitoring system to prevent severe thermal stress to pipes in early stages and to develop the non-intrusive techniques to diagnose the check valve because the thermal stratification has been caused by the malfunction of the check valve in ECCS pipe. Thermal stratification monitoring system has been designed and installed at ECCS line permanently and surge line temporally in YG nuclear power plant. The data is acceptable in according to TASCS guide line. Also, the data originated from ISMS is useful for the arrangement of a special UT program and stress analysis. Applying a togetherness of acoustics and magnetics signal, it is possible to determine the parameters of the function of the check valve internals without disassembling it. This series of tests show that the accelerometers can be use d to measure and to differentiate the three types of impacts; metal to metal impacts mechanical rubs, and worn internal parts. The magnet sensors can be used to detect the opening/closing of stainless check and fluttering of disk. (author). 50 refs., 5 tabs., 28 figs
[en] Electrochemical properties of Si/Ni/Cu film electrodes were investigated with different Ni film thicknesses (50-600 nm) and annealing temperatures (200-500 0C). The morphology of amorphous Si film was considerably affected by surface features of the Ni under-layer. The best cycle performance of 90.2% retention after 70 cycles was obtained from Si/Ni/Cu film with 300 nm thick Ni film and after 400 0C annealing. For the annealed Si/Ni/Cu electrode, the surface morphology (protrusions) and the formation of compounds among Si, Ni and Cu prohibited the volume expansion of Si during the charge-discharge process and enhanced adhesion between films and substrate, respectively.