Nevada National Security Site (Nevada Test Site)

Neptune and Company, Inc. developed a decision support system for the low-level radioactive waste program's performance assessment maintenance program. The low-level radioactive waste disposal facilities at the Nevada National Security Site (NNSS, formerly the Nevada Test Site) are required to perform and maintain environmental analyses to ensure protection of human health and the environment. This involves modeling of complex environmental systems to evaluate contaminant fate and transport, evaluation of human health risks, and optimization of closure, disposal, and monitoring programs.

At the NNSS there are many low-level waste sites with different characteristics that fall under different regulations. We took a decision framework approach to integrate the models of the different disposal systems by considering the needs of the closure, disposal, and monitoring decision endpoints. This approach allowed the costs of disposal and closure to be considered and the value of collecting more information through monitoring to be evaluated quantitatively. We provided a tool that effectively measures system performance, compares effects of different closure and disposal options, and allows control of monitoring using metrics that determine when the monitoring program can be terminated. The long-term intent is that the quantitative decision tool will be combined with presentation capabilities (e.g., geographic information system [GIS]) to provide a combined decision analysis, information system, and presentation system. This decision framework will serve as an effective management tool for low-level waste program managers at this site and similar sites.