Performance Assessment

A radiological performance assessment is conducted to provide reasonable assurance that performance objectives for radioactive waste disposal will be met. The performance assessment is instrumental in the postclosure of waste storage facilities. Neptune and Company, Inc. is widely regarded across the United States as an expert that designs probabilistic models to support the overall performance assessment process.

GoldSim Models Developed by Neptune and Company, inc.

So far, our modeling efforts have been aimed at supporting environmental decision making, though some modeling (the Smoky Site, in particular) involved a great deal more in the form of worker protection and cost/benefit analysis. We are in the process of building web pages discussing each of these models: 

  • A sample generic radiological performance assessment (PA). This Generic Performance Assessment is a GoldSim model provided as a working example of our modeling work.
  • An example of a Radioactive Waste Decision Model. This Decision Model provides an example of modeling a complex decision about the disposition of some problematic radioactive waste.
  • Contaminant transport at Material Disposal Area (MDA) G at Los Alamos National Laboratory (LANL), Los Alamos, New Mexico. (This work was presented as a poster at the Fall 2000 Meeting of the American Geophysical Union.)
  • Contaminant transport at the West Beach Landfill, at the former Naval Air Station Alameda, Alameda, California.
  • Decision analysis at the Smoky Site, at the Nevada Test Site (NTS), Nevada.
  • Contaminant transport and exposure assessment at MDA H at LANL.
  • Contaminant transport and compliance assessment at the Greater Confinement Disposal Boreholes at the Nevada National Security Site (NNSS, formerly the Nevada Test Site).
  • Contaminant transport, dose assessment, and decision analysis at the Area 5 Radioactive Waste Management Site (RWMS) at the NTS. This work has grown to encompass some waste operations decisions, as well as some challenging aspects of assessing the performance objectives of 40 Code of Federal Regulations (CFR) 191. (Some of this work was presented as a poster at the Fall 2002 Meeting of the American Geophysical Union.)
  • Contaminant transport and dose assessment for the Mochovce National Radioactive Waste Repository in the Slovak Republic. (This site is the topic of a talk delivered at the 2007 General Assembly of the European Geosciences Union in Vienna. The presentation can be found here.)
  • We have written three GoldSim PA models for the (DOE) Savannah River Site's E-Area Low-Level Waste Facility (ELLWF), in collaboration with Savannah River National Laboratory (SRNL).
  • EnergySolutions operates an LLW facility in Clive, Utah. We developed a GoldSim PA model to evaluate the potential disposal of depleted uranium (DU) at the Clive Facility. This model is the first of its kind in that DU is a highly unusual waste form in its long-term radiological characteristics. This model is available from the Utah Department of Environmental Quality. See UDEQ's web site on the EnergySolutions' Depleted Uranium Performance Assessment and scroll down to near the bottom to find out how to obtain a GoldSim Player version of the model.


GoldSim Models Under Development

We have several projects ongoing as well.  These varied sites provide us with continually evolving environmental and regulatory contexts, and allow us to hone our modeling skills further.

  • Waste Control Specialists operates an LLW facility in Andrews County, Texas. We are developing a GoldSim PA model for the Compact Waste Disposal Facility and Federal Waste Disposal Facility at this site.
  • We are consulting to Savannah River Remediation in the sensitivity analysis of three significant PA models in SRS's Liquid Waste side of the house. These models include the Saltstone Disposal Facility (SDF), and the F-Area and H-Area Tank Farms. These tank farms are host to several large (5000 m3) high-level waste tanks. Once the waste has been removed from the tanks, some of that waste will go to the SDF, and the remaining structures are subject to analysis under the 2004 National Defense Authorization Act Section 3116. In essence, this is a Performance Assessment, with performance objectives of NRC's 10 CFR 61.

See the presentation made at the 2003 GoldSim User's Conference. (This is a GoldSim model itself.)