[en] We have developed Check Valve Inspection System using acoustic emission sensor and ultrasonic sensor, to examine degradation and detailed motion (Full open, Tapping, Oscillation, etc.) of the swing check valve. This inspection system was applied check valves in the seawater system line of domestic nuclear power plants. The examination was carried out before and after replacing the check valve. Comparing the results of the inspection system and the results of overhaul, effectiveness of this system has been shown. (author)

[en] In order to study sorption behavior of U series radionuclides (Pb, Ra, Th, Ac, Pa and U) under aerated zone environment (loam-rain water system) and aquifer environment (sand-groundwater system) for safety assessment of U bearing waste, pH dependence of distribution coefficients of each element has been obtained. The pH dependence of distribution coefficients of Pb, Ra, Th, Ac and U was analyzed by model calculation based on aqueous speciation of each element and soil surface charge characteristics, which is composed of a cation exchange capacity and surface hydroxyl groups. From the model calculation, the sorption behavior of Pb, Ra, Th, Ac and U could be described by a combination of cation exchange reaction and surface-complexation model. (author)

[en] Distribution coefficients of Uranium series radionuclides such as Pb, Ra, Ac, Th, Pa as well as U were obtained under aerated zone and aquifer environments in order to have a database for the safety evaluation of shallow land disposal of uranium bearing waste. The distribution coefficients of them on four kinds of soil such as the loam in the rain water as for aerated zone environment and on three kinds of soil and rock such as the sand in the groundwater as for the aquifer environment have been measured by the batch method. The distribution coefficients in aerated zone environment were one or two orders of magnitude higher than those in the aquifer environment except Ac. There was an approximate linear relationship between the representative physical properties of the soil, such as the cation exchange capacity and the specific surface area, and the distribution coefficient of lead, radium and protactinium. (author)