GoldSim E-Area Low-Level Waste Lacility Vadose Zone Model Benchmarking

Hamm

et al. 2023

air, and radon. This section describes the development and implementation of conceptual models for STs and ETs for the GW protection pathway. The ST and ET conceptual models for the IHI exposure pathway are described in Section 3.7.3 and Section 7.3. ST and ET conceptual models for the air and radon pathways are described in Section 3.6. STs and ETs are considered together in this section because the similarities in their facility design; waste characterization; and physical, hydraulic, and chemical properties result in the same (or nearly the same) GW conceptual model.A GW transport analysis is conducted to determine maximum radionuclide concentrations as a function of time within the 100-meter POA buffer zone. PORFLOW (ACRi, 2018), which models both steady-state and transient flow and transport of radionuclide chains (parents and daughters) in porous media, is the primary analysis tool used. Two-and three-dimensional flow and transport analyses are performed to describe, in detail, the migration of species from the trench waste zones downward through the VZ to the underlying water table . VZ simulations (treated as source terms) results are input into a 3-D aquifer transport model to compute maximum GW concentrations of radionuclides within the 100-meter POA. Preliminary GW protection and all-pathways disposal limits for STs and ETs over the 1,000-year period of performance are developed from the computed maximum GW concentrations using the PA/CA Performance Assessment for the Implementation of Groundwater Modeling E-Area Low-Level Radioactive Waste Disposal Facility at the Savannah River Site SRNS-RP-2022-00270 / SRNL-STI-2021-00388 Revision A 4-5completed stack of boxes using a bulldozer. This step brings the trench up to grade and fills in voids between the individual boxes and between the stacks of boxes and the trench sidewalls.Based on this conceptual model, Phifer (2010) developed, and Nichols and Butcher (2020) later refined, a recommended set of blended material and hydraulic property values for containerized waste disposal in STs before and after dynamic compaction (see Table 4-1). This conceptual model also applies to containerized waste in ETs as discussed in Section 4.1.1.2.Inputs and assumptions for the blending calculations are as follows (SRNL, 2020):• The outside dimensions of a B-25 box are 6.0182-foot long, 3.8482-foot wide, and 3.9353-foot high, equating to an average exterior volume of 91.1380 ft 3 (2,580,742 cm 3 ).• The inside dimensions of a B-25 box are 6.0000-foot long, 3.8300-foot wide, and 3.9170-foot high, equating to an average interior volume of 90.0127 ft 3 (2,548,875 cm 3 ).• The volume of waste in a B-25 box is equal to the interior volume 90.0127 ft 3 (2,548,875 cm 3 ); the total waste volume in a stack of four B-25 boxes is 360.0506 ft 3 (10,195,499 cm 3 ).• The average density of uncompacted waste within a B-25 box is 0.1785 g cm -3 (Phifer and Wilhite, 2001).• The total waste mass in a four-high stack of B-25 boxes is 1,819,897 grams (10,195,499 cm 3 × 0.1785 g cm -3 ).• Th...

Section: Automated Implementation Of Three-dimensional Modelsmentioning

confidence: 99%

Section: Example Porflow Vadose Zone Model Implementation For Central...mentioning

confidence: 99%

See 1 more Smart Citation

Performance Assessment for the E-Area Low-Level Radioactive Waste Disposal Facility at the Savannah River Site: Chapter 4

Hamm

et al. 2023

“…This section introduces the methodology employed by Wohlwend and Aleman (2020) to develop the simplified 1-D GoldSim ® VZ flow and transport models for STs and ETs. The application of this methodology in benchmarking the VZ component of the GoldSim ® System Model for ETs and STs is discussed in Sections 4.4.8 and 4.4.9, respectively.…”

Section: Goldsim ® Vadose Zone Transport Model Developmentmentioning

confidence: 99%

Performance Assessment for the E-Area Low-Level Radioactive Waste Disposal Facility at the Savannah River Site: Chapter 3

HAMM

et al. 2023

are the PA for the INTEC calcined solids storage facility at the Idaho National Laboratory site (DOE-ID, 2019) and the PA for Waste Management Area C at the Hanford site (Mehta et al., 2016). The PA evaluates the potential impacts of changes in performance of different features of the system and demonstrates that the safety functions represent multiple and redundant barriers. Barrier analyses, assuming a safety function is not present, also test the robustness of the system in the event of the loss of one or more safety functions. Such evaluations also support a qualitative illustration of the concept of defense-in-depth.The safety concept for closure of the ELLWF encompasses a variety of different features (i.e., administrative controls, natural site features, and engineered barriers) that reduce the potential impacts on human health and the environment from the residual waste that will remain after closure. These features can be represented as a collection of safety functions acting independently and as a system to provide for overall safety. In some applications, attempts are made to assign numerical expectations to specific safety functions, but that is not the intent in this case. The concept of safety functions is used more qualitatively in two ways for this PA: 1. To illustrate the robustness of the ELLWF design, operational practices, and closure approach by documenting features that are and are not credited in different modeling cases.

“…The waste zone height before dynamic compaction for STs (and ETs) is 16 feet Wohlwend and Aleman (2020). assumed a thickness of 8.87 feet for the ST hybrid waste zone after dynamic compaction per PA2008.…”

mentioning

confidence: 99%

Performance Assessment for the E-Area Low-Level Radioactive Waste Disposal Facility at the Savannah River Site: Chapter 2

Hamm

et al. 2023

According to U.S. Census Bureau's annual estimates of resident population, based on 2010 census data, the estimated 2019 population in the eight-county region of influence (ROI) is 610,073 (Table 2-2). Four counties each are in South Carolina (Aiken, Allendale, Bamberg, and Barnwell) and Georgia (Burke, Columbia, Richmond, and Screven). The ROI includes counties within and immediately adjacent to SRS (see Figure 2-2) where most SRS workers reside. Approximately 87% of the eight-county 2019 estimated population lived in three counties: Aiken County, SC (28.0%), Columbia County, GA (25.7%), and Richmond County, GA (33.2%). The balance of the eight-county 2019 estimated population (~13%) lived in Allendale, Barnwell and Bamberg counties in South Carolina and Burke and Screven counties in Georgia. Table 2-2. Population Distribution and Percent of Region of Influence for Counties and Selected Communities Jurisdiction 2019 Population Estimate 1 2019 %ROI SOUTH CAROLINA