Steam direct contact condensation in subcooled water is an inevitable process in pressure suppression system of advanced light water reactor. Ten pure steam experiments have been performed in the range of steam mass flux 5-80 kg/m(2) s and water temperature 19-96 degrees C. The steam condensation behave, fluid oscillation and pressure oscillation are recorded and analyzed. Prominent small bubbles are observed on the bubble surface due to the Rayleigh-Taylor instability. Vortex ring appears after aspherical bubble collapses. The upper threshold of chugging is identified by temperature data acquired continuously. The amplitude and frequency of fluid oscillation are obtained and compared with previous correlations. Two typical pressure wave shapes of continuous oscillation and pulse oscillation are identified. The pulse oscillation is induced by steam bubble collapse and observed at low water temperature. The maximum pressure pulse peak is about 1 MPa measured in the nozzle and 0.1 MPa in the pool. The pressure oscillation intensity in the water pool increases first, then decreases rapidly, and then increases slowly. It has a maximum at water temperature about 55-75 degrees C and the related temperature increases with the increment of the steam mass flux. The pressure oscillation dominant frequency is analyzed and compared with available correlations. (C) 2018 Elsevier Ltd. All rights reserved.