The development of 3-D image processing acoustic simulator for under sodium viewing technology

One of the technologies indispensable for development of USV is the simulation technology for evaluating the characteristics of ultrasonic acoustic propagation under sodium in the reactor vessel. In this report, the sound sources superimposed method (SOSUM) is introduced as the simulation technology. In SOSUM, at first , the ultrasonic echoes, which are transmitted from the transmitters and reflected by structures, are calculated as reflecting sound sources. Then, ultrasonic time-series waves received on each receiver are expressed as superimposition of contribution from all transmitted sound sources and reflecting sound sources. The extension of SOSUM to inhomogeneous media is discussed. When temperature fluctuation exists along the ultrasonic transmitting path, acoustic characteristics are inhomogeneous. In this case, the inhomogeneous media are divided to many small divisions in which acoustic characteristics are regarded as homogeneous. However, the extended SOSUM requires huge calculation volume, and thus higher speed techniques are necessary for practical use. In this report, the higher speed techniques with parallel processing are proved to be effective for SOSUM. It is shown that for practical use of 3-D image processing simulator of USV, parallel processing hardware with a high ability of floating point arithmetic and a capability of executing independent code for eachmore » processor is needed.« less