WIPP WAC Equivalence Support Measurements for Low-Level Waste at Los Alamos National Laboratory

Los Alamos National Laboratory (LANL) uses the Nevada National Security Site (NNSS) as an off- site disposal facility for low-level waste (LLW). NNSS has issued a position paper that indicates that systems that are not certified by the Carlsbad Field Office (CBFO) for Waste Isolation Pilot Plant (WIPP) disposal of Transuranic (TRU) waste must demonstrate equivalent practices to the CBFO certified systems in order to assign activity concentration values to assayed items without adding in the Total Measurement Uncertainty (TMU) – i.e., only using the system’s reported assay value – when certifying waste for NNSS disposal. The LANL LLW Characterization Team uses portable high purity germanium (HPGe) detector systems for the nondestructive assay (NDA) of LLW. A number of performance studies have been conducted historically by the gamma spectroscopy team to support the efficacy and quality of assay results generated by the LANL HPGe systems, and, while these detector systems are supported by these performance studies and used with LANL approved procedures and processes, they are not certified by CBFO for TRU waste disposal. During 2010, the LANL LLW Characterization Team undertook additional NDA measurements to supplement existing studies and procedures to demonstrate full compliance with the NNSS position paper. Where possible, Performance Demonstration Project (PDP) drums were used for the waste matrix and PDP sources were used for the radioactive sources. These LANL owned PDP drums and sources were graciously shared by the Central Characterization Project (CCP) and Mobile Characterization Services (MCS) at LANL, who have priority for their use for WIPP characterization activities. The methodology used, examples of the measurements, and analysis results are presented in this paper. NNSS has accepted the methodology and results of the measurements as demonstrating equivalence to CBFO certified systems.