Spectral Interferences in Oak Ridge Wastes

Oak Ridge National Laboratory is a research facility, and its transuranic (TRU) wastes are more complex and varied than those from weapons-production sites. Each container of waste must be characterized before it can be transported to the waste repository in New Mexico, and the complexity of Oak Ridge National Laboratory wastes makes their characterization quite challenging. Gamma spectrometry is the usual method for transuranic waste characterization in Oak Ridge, but certain radionuclides in the waste emit no usable gamma radiation. Other radionuclides may emit detectable gamma radiation, but their spectral “fingerprints” are ambiguous because gamma rays from some radionuclides are very close in energy to those emitted by others. This paper presents data from several individual assays, to illustrate how spectral ambiguities may be resolved.