Holdup measurements for three visual examination and TRU remediation glovebox facilities at the Savannah River Site

Abstract

Visual Examination (VE) gloveboxes are used to remediate transuranic waste (TRU) drums at three separate facilities at the Savannah River Site. Noncompliant items are removed before the drums undergo further characterization in preparation for shipment to the Waste Isolation Pilot Plant (WIPP). Maintaining the flow of drums through the remediation process is critical to the program’s seven-days-per-week operation. Conservative assumptions are used to ensure that glovebox contamination from this continual operation is below acceptable limits. Holdup measurements using cooled HPGe spectrometers are performed in order to confirm that these assumptions are conservative. 239Pu is the main nuclide of interest; however, 241Pu, equilibrium 237Np/233Pa and 238Pu (if detected) are typically assayed. At the Savannah River National Laboratory (SRNL) facility 243,244,245Cm are also generally observed and are always reported at either finite levels or at limits of detection. A complete assay at each of the three facilities includes a measure of TRU content in the gloveboxes and HEPA filters in the glovebox exhaust. This paper includes a description of the γ-PHA acquisitions, of the modeling, and of the calculations of nuclide content. Because each of the remediation facilities is unique and ergonomically unfavorable to γ-ray acquisitions, we have constructed custom detector support devices specific to each set of acquisitions. This paper includes a description and photographs of these custom devices. The description of modeling and calculations include determination and application of container and matrix photon energy dependent absorption factors and also determination and application of geometry factors relative to our detector calibration geometry. The paper also includes a discussion of our measurements’ accuracy using off-line assays of two SRNL HEPA filters. The comparison includes assay of the filters inside of 55-gallon drums using the SRNL Q2 assay system and separately using off-line assay with an acquisition configuration unique from the original in-situ acquisitions.