Year
2001
Abstract
Plutonium holdup measurements were conducted in the dry cabinets of FB-Line at the Savannah River Site. The main function of FB-Line is to convert plutonium nitrate recovered from irradiated natural and depleted uranium in the F-Canyon processes to plutonium oxide or metal. The results of the holdup measurements are essential for determining compliance with Material Control & Accountability Regulations and to address an open Office of Security Evaluation (OSE) finding in process areas of FB-Line. All holdup measurements were carried out using a portable gamma ray spectroscopy system consisting of a 5cm x 5cm sodium iodide (NaI) detector system (Canberra detector 03001722 model # 802), an EG&G MicroNomadÔ pulse electronics/multichannel analyzer unit. The detector had a cylindrical steel cladded lead collimator about 1.3 cm (½-inch) thick that projected a distance of 5cm beyond the detector face. All acquisitions were made using the NaI detector-collimator assembly at a 45° angle with varying heights (15-46cm) from the surface to be measured. Since the calibration factor used in calculating the amount of Pu holdup was derived by using a different geometry, this report discusses the development of a geometry correction factor for the calibration constant. The methodology, measurements, assumptions, calculations and corrections, and results will be discussed.