Implementation of AWCC measurements at the South African Nuclear energy Corporation (Necsa)

摘要

South Africa signed and ratified the NPT in 1991, signed the Safeguards Agreement in September 1991 and signed the Additional Protocol in 2002. During this period, the SSAC was established and developed, however, not much attention was afforded its NDA capability. As recent as 2008 this started to change with the acquisition of a few more NDA personnel, equipment, basic and advanced training. With the skills gained by its NDA personnel to date, the South African SSAC was able to develop an NDA programme to ensure that declarations to the IAEA by the various facilities at Necsa are all credible. When using the Active Well Coincidence Counter (AWCC) to quantify bulk materials, it is important to calibrate the instrument with reference material that is similar in geometry, material composition, enrichment, etc. This will help generate a representative calibration curve that will facilitate accurate estimations of the ~(235)U mass in the sample. In cooperation with Oak Ridge National Laboratory, the initial implementation of the AWCC system was performed. This included development of the calibration curves and validation of a general material calibration curve. We present in paper the results of these measurements, challenges that were encountered and lessons that were learned.