Study for the Construction of Gas Leak Detection System in Nuclear Power Plants Using Ultrasound

Abstract

On March 11, 2011, a serious accident occurred at the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company Holdings, Inc. due to the Great East Japan Earthquake and tsunami. Currently, nitrogen gas is used to fill the reactor containment vessel, pressure vessel, and plant piping to prevent a hydrogen explosion. Gas leak detection technology is needed to maintain and control the integrity of nitrogen gas containment and to ensure plant safety, as well as to identify the leak location in the event of a leak and understand the nature of the leak before plugging the leak location. However, because of the high radiation environment in the plant, it is not practical for a person to enter the plant to detect gas leakage. Therefore, there is a need for a leak detection method for gases that can be used in a radiation environment, and that is compact, measurable, and can be loaded by robots. In this study, we focused on acoustic gas leak detection as a leak detection technique. The characteristics of ultrasound generated by gas leakage were investigated for the development of gas leak detection technology and source localization system in nuclear reactors.