Fundamental study for elemental analysis using sonoluminescence in aqueous solution

The retrieval of fuel debris after the Fukushima Daiichi Nuclear Power Plant accident is crucial. Analysis of the elemental composition around the debris is one of the effort to contribute on this purpose. Remote and high radiation resistant device is required due to high radiation condition. The combination of online ultrasonic sonication, light transmission using optical fiber, and further consideration of the effect of intense radiation to the system, enables the remote elemental analysis system using sonoluminescence (SL). The specific light that emitted from the collapsing gas bubble under ultrasonic sonication with the presence of argon gas is used to analyze the element on the liquid solution. As a fundamental study of the elemental analysis using SL, the SL of a different element, frequency, power, the SL of nuclear-related elements such as boron and cesium, the effect of concentration, and the enhancement of SL intensity were presented. The experiment was conducted using the equipment consists of a commercial ultrasound transducer unit, ultrasound controller, sample container, and still camera. The various metal aqueous solutions saturated with argon gas was used. The dependence of the parameters on SL characteristic was investigated using strontium aqueous solution with three frequency variations (26, 78 and 130 kHz) in the power range 0-50 W. The photograph showed the SL relative intensity was increased by the increase of ultrasonic power and frequency. Hence, the range of optimum operation condition can be estimated. The SL of various elements was visualized including the effect of the solution concentration. Finally, the enhancement of SL intensity was done by the continuous injection of argon gas. (author)