External Surveillance of Geothermal Scale Deposits Employing Iridium-192 Radiography

Abstract

Iridium-192 radiography has been successfully tested as a technique for externally monitoring geothermal scale deposits in piping at the Brawley, CA geothermal field. This technique is applied to piping that handles flowing brine to provide in situ scale deposition observations without the disadvantage of dismantling piping for visual scale inspection. Exposure times and film orientations have been optimized to yield excellent agreement between radiographically detected scale thicknesses and actual thicknesses observed in dismantled pipe. This technique can detect scale buildup in pipes to 1-2 m accuracy. Radiography has also detected corrosion in piping. Development of this technique is shown to be useful of monitoring continuous geothermal brine processing operations.