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Waste Management Facility Performance Assessment

Waste Management Facility Performance Assessment

Waste Management Facility Performance Assessment

SC&A radiochemists, scientists, engineers, and NQA-1 trained auditors understand all types of radioactive and hazardous wastes and their governing regulations, including:

  • High-level radioactive waste and spent nuclear fuel
  • Transuranic waste, both remote-handled and contact-handled
  • Low-level radioactive waste (LLRW)
  • 10 CFR Part 194 and DOE’s WIPP Waste Acceptance Criteria

For government and national and international commercial enterprises, we:

  • Inspect and approve systems and processes to assay hazardous waste
  • Audit radioactive waste packaging procedures to ensure compliance with regulatory commitments
  • Analyze radionuclide transport through fractured media at variable densities and saturation
  • Support technical analysis for federal agency rulemaking
  • Model seismic events, climate change, potential flooding, and precipitation effects
  • Model waste package and drip shield degradation and the long-term performance of engineered barrier systems and other containment
  • Assess waste form degradation and radionuclide release
  • Audit and inspect waste-generating and storage sites
  • Perform advanced numerical modeling to assess future performance beyond 10,000 years, including TOUGH2 and GoldSim computer codes

Sample Projects

Depleted Uranium Performance Assessment. SC&A is supporting the State of Utah’s Department of Environmental Quality, Division of Waste Management & Radiation Control, in reviewing EnergySolutions’ depleted uranium (DU) performance assessment (PA) and the modeling report and other documents related to the proposed disposal of DU at the Clive, UT facility. SC&A acted as an extension of the Division—interpreting regulations and evaluating licensing submittals against them, preparing requests for additional information, prepared a draft safety evaluation report, and participated in outreach meetings with the public and the media. Although DU is considered to be Class A LLRW, the disposal of large quantities of DU was not considered in the final 10 CFR Part 61 rulemaking. The Division promulgated regulation R313-25-9(5) to address the unique concerns associated with DU disposal, which included a 10,000-year Compliance Period dose assessment and a “deep time” (i.e., peak dose) qualitative analysis. SC&A based our technical review of the parameters and methodologies used in the DU PA on that regulation. SC&A provided specialized expertise in GoldSim modeling, geology, meteorology, civil, nuclear, and environmental engineering, geochemistry, hydrology, climatology, and radiological engineering and health physics.

Waste Isolation Pilot Plant (WIPP). Under the WIPP Land Withdrawal Act, the U.S. Environmental Protection Agency (EPA) is required to initially certify and every 5 years recertify that the U.S. Department of Energy (DOE) complies with the radiation protection standards of 40 CFR Part 191. SC&A has been supporting the EPA Office of Radiation and Indoor Air in this effort. SC&A’s geologists, hydrogeologists, geochemists, statisticians, health physicists, waste characterization specialists, quality assurance specialists, and mining engineers prepared a detailed review and critique of the entire original DOE WIPP application. This included a thorough examination of the WIPP long-term (10,000-year) PA and identification and evaluation of all significant features, events, and processes. SC&A applied advanced numerical modeling to assess the long-term integrity of the WIPP site, including two- and three-dimensional modeling that involved multi-phase flow and radionuclide transport through fractured media at variable densities and under partially saturated conditions. Based on the reviews and resolution of responses, DOE prepared an updated PA, which SC&A validated to ensure compliance with EPA regulations. Since then, SC&A has supported EPA WIPP recertifications, including the July 2017 recertification, the most recent. SC&A also supports EPA inspections and approvals of all waste characterization processes for transuranic wastes from DOE sites intended for disposal in the WIPP.

Yucca Mountain. A 2004 court decision required EPA to revise the standards for waste disposal at Yucca Mountain in 40 CFR Part 197. To help EPA understand how the natural barriers would contribute to long-term uncertainty in repository behavior, SC&A conducted a PA of the proposed Yucca Mountain repository, using GoldSim to evaluate the effects of infiltration rates, seepage factors, and radionuclide solubilities on uncertainty in the mean peak dose for periods out to one million years. To determine each parameter’s contribution to the uncertainty, it was necessary that the PA hold some parameters at their mean, while others were permitted to vary. GoldSim was not able to perform this type of analysis; therefore, SC&A developed an Excel spreadsheet GoldSim driver that accepted the distributions as input and returned values for each parameter of interest. The spreadsheet also allowed for individual GoldSim variables to be turned on and off, making it possible to study the sensitivity of the results to individual variables. The results of SC&A’s PA of reference dose level uncertainty are publicly available.

Uranium and Thorium Mill Tailings. When EPA was considering revising 40 CFR Part 192, “Health and Environmental Protection Standards for Uranium and Thorium Mill Tailings,” SC&A used standard pathway modeling to develop a probabilistic assessment model using Excel with the Chrystal Ball add-in. To execute the transitioned probabilistic assessment, SC&A developed probability distributions for the model input parameters (e.g., usage factors, exposure times, food consumption rates, bioaccumulation factors). Along with the standard groundwater exposure pathways, SC&A included unique pathways associated with Native American practices (e.g., sweat lodge exposures), indoor radon, embryo and fetus exposure, and infant consumption of dry formula (mixed with well water), cow’s milk, and breast milk. The SC&A-developed probabilistic assessment model underwent peer review by EPA experts who were not associated with the Part 192 update. EPA ultimately decided not to pursue the Part 192 revision.

Recycling & Waste Facility Reviews. For corporate, nonprofit, and government clients worldwide, SC&A conducts recycling and waste facility reviews of manufacturers, medical waste facilities, municipal solid waste landfills, fuel-blending facilities, scrap processing and recycling plants, waste-to-energy facilities, and oilfield waste transfer stations.

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