Gamma scanning technique on geothermal pipe scale thickness measurement

Pipe scale is the most common problem in geothermal power plants. Gamma scanning is a non-destructive test method to analyze how thick scale is formed in the pipe, without opening or damaging the pipe. Consequently, the approach can be used during operation. Gamma radiation source, Cs-137 with an activity of 2.96x103 GBq is used as a gamma ray emitter that penetrates the object and is detected by a scintillation detector. Pipe samples from one of the geothermal power plants which only operated in 2018 in the Karaha area, West Java, Indonesia were used as objects. The scan profile describes the conditions inside the pipe, showing where the scale is formed and how thick it is. The real thickness of the scales varies from 80-180 mm in the pipe. From the experimental results was found that the variation of the scale is from 83-183 mm, from 16 measurements projection with different angles, so that visualization was obtained in the pipe. Further research is needed to perfect this method.