Basic test of acoustic emission sensor as a leak detector from pressure vessels and piping of nuclear power plant

Basic tests of AE (Acoustic Emission) sensor that measures elastic wave of solid caused by leak of high pressure vessels, pipes or valves have been performed. The relation of leak flow rate and AE sensor's signal level, and the characteristics of AE signal attenuation vs. distance have been obtained experimentally as basic data. The test system consists of a pipe that can contain gas, water or steam whose maximum temperature is 275degC and maximum pressure is 6 MPa. A small scale crack is simulated by a small circular hole or a slit type rectangular shaped hole. It is observed that the AE signal level generated from leak part is proportional to the density of leaking fluid, to the fourth power of the velocity and to the cross sectional area of simulated crack. It is also observed that AE signal attenuation against distance on uniform cross section pipe is negligible small. This basic technology can be applied to detect leak from pressure vessels and piping in a nuclear power plant. (author)