SRS Controlled-Potential Coulometer

'The Savannah River Site has the analytical measurement capability to perform high-precision plutonium concentration measurements by controlled-potential coulometry. State-of-the-art controlled-potential coulometers were fabricated by the SRS Engineered Equipment and Systems Department and installed in the Analytical Laboratories'' process control laboratory. The Analytical Laboratories uses coulometry for routine accountability measurements of pure plutonium from the PUREX process and for verification of standard preparations used to calibrate other plutonium measurement systems routinely applied to process control, nuclear safety, and other accountability applications. The SRS Coulometer has a demonstrated measurement reliability of approximately 0.05 percent for 10 mg samples. The system has also been applied to the characterization of neptunium standard solutions with a comparable reliability. The SRS coulometer features: a patented current integration system; continuous electrical calibration versus Faraday''s Constants and Ohm''s Law; the control-potential adjustment technique for enhanced application of the Nernst Equation; a wide operating room temperature range; and a fully automated instrument control and data acquisition capability. The system has been operated for 10 years with minimal equipment failures and downtime. The coulometer and instrument controller have been periodically upgraded to remain current with available high-precision potential control and current integration components. A stability of 261 0.0015 percent RSD for the electronic calibration factor has been demonstrated. Most recently the system was converted from an Hewlett Packard computer platform to an IBM Computer Windows-based system. SRS Coulometers were installed at the Tokai-mura Reprocessing Facility in Japan in February 1999 and at the Mayak Production Association in Ozersk Russia in October 1998.'