Development of a Continuous, Unattended Quality Control Method for a Permanently Installed Holdup Measurement System

The Surplus Plutonium Disposition (SPD) Project is constructing a series of gloveboxes at the Savannah River Site (SRS) to unpack, dilute, and repackage surplus plutonium. Plutonium control and accountability is central to the SPD mission and requires frequent physical inventories. The current methodology to measure holdup requires the use of collimated high-purity germanium detectors, taking sequential measurements for a series of locations. Shielding on the gloveboxes, which is important for reducing worker dose, further complicates current measurement techniques. Savannah River National Laboratory (SRNL) and Oak Ridge National Laboratory (ORNL) have partnered to develop an improved methodology for holdup measurement: the Gamma Imagery Light Fixture Assembly (GILFA) is a fixed gamma-ray imaging system mounted to the ceiling of the glovebox that will provide a continuous measurement of material inside the glovebox. A key design requirement for the GILFA system is to validate the measurement capabilities of the detectors at any point in time. To meet this requirement, SRNL has developed a quality control system (QC) using three (3) stationary, permanent calibration sources mounted beneath the glovebox. The source selection, the effectiveness of this QC system on the GILFA system, and the dose rates that the QC system would impose on glovebox workers have each been evaluated using an MCNP6 model of the proposed glovebox and GILFA system.