APPLICATION OF CONTROLLED-POTENTIAL COULOMETRY AS A PRIMARY METHOD FOR THE CHARACTERIZATION OF PLUTONIUM NITRATE SOLUTIONS BEING USED FOR LARGE-SIZE DRY SPIKE REFERENCE MATERIALS; COLLABORATION BETWEEN JAEA AND SRNL

Since November 2007, the laboratory at the Japan Atomic Energy Agency’s (JAEA) Tokai Reprocessing Technology Development Center (TRTDC) and Savannah River National Laboratory (SRNL) have collaborated on a new mission to apply controlled-potential coulometry as a primary method for characterizing plutonium master solutions. Measurement results are being used to prepare traceable and certifiable large-size dry (LSD) spike standards for safeguards measurements by isotope dilution mass spectrometry. Activities included: returning to service two previously installed 1998-vintage SRNL Coulometers; upgrading them to the 2006 SRNL-design; performing periodic component and system calibration; pursuing sustainability and human capital development; and ensuring effective application of a measurement service that is fit-for-purpose. Ensuring analytical fitness included: compliance with ISO 12183 (Pu coulometry assay); qualification versus appropriate acceptance criteria; traceability to the International system of units (SI); application of appropriate measurement controls; and uncertainty propagation in accordance with JCGM 100:2008 (ISO-GUM, current version). The collaboration on upgrades, calibration services, human capital development, and the analytical fitness activities performed by JAEA and SRNL were authorized and funded under the JAEA & United States NNSA/DOE Permanent Coordinating Group. This report will chronicle the collaboration activities of JAEA and SRNL, and provide the detail on the periodic coulometer component calibrations, the coulometric plutonium measures and measure practices, including the uncertainty propagation for the most recent plutonium master solution used for LSD Spike preparation.