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The spectral summing technique developed by Pajarito Scientific Corporation (PSC) is a unique modeling technique that is being employed by the Waste Disposition Project - Low Level Waste Disposal (WDP-LLWD) Group at Los Alamos National Laboratory (LANL). This technique is being used to disposition low-level radioactive waste that has dropped out of the transuranic (TRU) category and has no place to go unless it can be proven to be LLW and not TRU. The TRU program at LANL run by Mobile Characterization Services (MCS) employs two High Efficiency Neutron Counters (HENC) with built-in gamma assay systems to assay radioactive waste for shipment and disposal as TRU waste at the Waste Isolation Pilot Plant (WIPP) at Carlsbad, New Mexico. As well as being certified for WIPP assays, the HENC systems can also be used for lowlevel waste assays for disposal at LANL or off-site disposal facilities, such as the Nevada Test Site (NTS). Some of the waste processed through the HENC systems cannot be confirmed TRU due to the absence of detected TRU alpha emitters above the TRU cutoff of 100 nCi/g. This waste becomes suspect low-level waste (SLLW). In many cases, the waste also can't be classified as LLW because the minimum detectable activity (MDA) of TRU radionuclides is above the 100 nCi/g level. These wastes that do not have enough detectable TRU activity to be classified as TRU waste and have too high a MDA to be classified as LLW enter a radioactive waste characterization limbo that prevents their dispositioning as either TRU waste or LLW. Spectral summing allows an experienced gamma spectroscopy analyst to add the HENC gamma spectra of a number of similar waste items together to form a consolidated (summed) spectrum. This summed spectrum contains the assay results of the group of items rather than the individual item, and gamma peaks that were not discernable in the individual spectra become quantifiable in the summed spectrum. The group of waste items can then be properly classified as LLW based on the summed spectrum and valid assay values can be assigned for disposal. This technique is being successfully used to dispose of LLW debris drums from LANL. [ABSTRACT FROM AUTHOR]

The Los Alamos National Laboratory (LANL) Plutonium Facility (TA-55) and the Chemistry and Metallurgy Research (CMR) building are radiological facilities operated by the Nuclear Materials Technology (NMT) Division. The operations within the radiological control areas (RCAs) of NMT Division generated approximately 262 m³ of low-level wastes (LLW) per year from the routine disposal of laboratory room trash. The process for the generation and disposal of LL and GIC wastes from RCAs is shown in Figure 1. It is estimated that as much as 50% of LLW boxes are free of radioactive contamination and are suitable for inclusion in the GIC waste program. [ABSTRACT FROM AUTHOR]