Total gamma count rate analysis method for characterizing transuranic waste.

摘要

Gamma-ray spectrometry systems are used in a variety of applications. However, the ability to characterize transuranic waste with a gamma spectroscopy system and have a minimum detection limit of less than 10 nCi/g of transuranic activity concentration is difficult with conventional photopeak analysis routines. The objective of this research is to determine the viability of the integral count method for characterizing transuranic waste and achieve a minimum detection limit of 10 nCi/g of transuranic activity concentration. The Idaho Cleanup Project sponsored the total gamma count rate research project to determine if this method could be used in waste retrieval operations at the Idaho National Laboratory Site.;The total gamma count rate is a measure of the total number of gamma interactions that produce energetic electrons or positrons seen in a detector. The interactions are photoelectric effect, Compton scattering, electron-positron pair production, and multiple gamma-ray scattering events.;A two-tier approach was used in this research project: (1) assess real waste data previously collected at the Idaho National Laboratory Site and (2) use simulated transuranic waste containers. Both tiers were designed to determine if the total gamma count rate analysis method could characterize transuranic waste for disposal and if a nominal minimum detection limit of 10 nCi/g of transuranic activity concentration could be obtained. The real waste assay analyses targeted filters, graphite, organic sludge, and inorganic sludge while the simulated transuranic waste containers targeted filters, graphite, organic sludge, and inorganic sludge, and sand.;The total gamma count rate analysis method results for real waste assay data and the results for simulated waste assay data were linear within statistical accuracy with respect to the expected or known value thereby indicating applicability to characterize transuranic waste for disposal.;Using Currie's formula to determine minimum detection limits, the predicted MDLs were less than 10 nCi/g transuranic activity concentration for each real waste matrix and for the simulated transuranic waste containers.;This research demonstrated that the total gamma count rate analysis method can be used for characterization of transuranic waste for disposal purposes and achieve a minimum detection limit of 10 nCi/g of transuranic activity concentration.