Hydraulic Properties Data Package for the E-Area Soils, Cementitious Materials, and Waste Zones - Update

Nichols, R.L.; Butcher, B.

doi:10.2172/1591780

Cited by 13 publications

(97 citation statements)

References 64 publications

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“…The interim and final covers are placed at relative year 46 and 171, respectively. In addition to the intact infiltration conditions, four CIG units, CIG-4 through CIG-7, contain components or low-density waste that are not filled with grout and have been estimated to have a maximum of 7 feet of subsidence potential (Nichols and Butcher 2020). In the conceptual model implementation, subsidence is assumed to occur only over the waste zone (i.e., excluding the grout encapsulation along the walls of the trench segment) where settling and degradation of the composite cementitious waste form occurs.…”

Section: Timeline and Boundary Conditionsmentioning

confidence: 99%

“…The specific values of the physical and chemical properties of the composite cementitious waste form and the surrounding native soils of the upper and lower vadose zone are discussed in the SRNL Hydraulic Properties Data Package (Nichols and Butcher, 2020) and the SRNL Geochemical Data Package (Kaplan, 2016). As water passes through the CIG wasteform, chemical constituents are leached from the cementitious materials which leads to a gradual physical degradation and a decrease in the hydraulic integrity (i.e., increased porosity and hydraulic conductivity).…”

Section: Physical and Chemical Propertiesmentioning

confidence: 99%

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Component-In-Grout Model Implementation for the E-Area Low-Level Waste Facility's Performance Assessment

Danielson

2020

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The component-in-grout (CIG) disposal units are below grade earthen trenches that contain grout encapsulated waste components. Components disposed of within the CIG segments consist of large radioactively contaminated equipment and smaller waste forms (e.g., B-25 boxes and SeaLand containers) to fill the space around and above the large equipment. In the 2022 revision of the E-Area Low-Level Waste Facility's (ELLWF) performance assessment, groundwater radionuclide contaminant transport through the vadose zone will be modeled using the PORFLOW software package for nine existing CIG segments located within the Slit Trench (ST) 23 footprint-no additional CIG segments are planned for at this time. The nine CIG segments have been placed within two of the nominally 20-foot-wide by 656-footlong ST segments and are surrounded by no less than 1 foot of grout on all sides and up to 4 feet of backfill material. The two most recently placed CIG segments have an additional reinforced concrete mat to improve structural stability.

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Section: Timeline and Boundary Conditionsmentioning

confidence: 99%

Section: Physical and Chemical Propertiesmentioning

confidence: 99%

Component-In-Grout Model Implementation for the E-Area Low-Level Waste Facility's Performance Assessment

Danielson

2020

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“…The surface-soil layer (Box 1) represents the areal footprint and nominal or compacted/collapsed waste height of each DU model. The surface-soil layer (Box 1) and unsaturated-soil layer (Box 2) are modeled as a sandy soil sediment (Nichols 2020). The starting inventory of the parent nuclide is initialized to the atom number equivalent of 10 12 pCi divided by the decay constant of the parent nuclide.…”

Section: Tier-1 Nrcdwsm Groundwater Radionuclide Screeningmentioning

confidence: 99%

Groundwater and Intruder Radionuclide Screening

Aleman

Hamm

2020

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Solid Waste Management (SWM) operates the E-Area Low-Level Waste Facility (ELLWF) where low level on-site and off-site solid waste streams are buried. The facility has been in operation since late 1994 and is currently projected to remain in operation until 2065. This facility can accommodate a broad range of waste forms resulting from the six different types of disposal unit options (i.e., varying degrees of engineered barriers  trenches to concrete vaults). This facility is currently operating under a Performance Assessment (PA) issued back in 2008, along with several subsequent supporting Special Analyses (SA). The Savannah River National Laboratory (SRNL) developed the prior PAs and SAs and has been tasked to update the facility's PA. For operating the E-Area facility, a Waste Inventory Tracking System (e.g., WITS) is actively employed by waste generators where every radionuclide entering the facility (to be buried in one of its many disposal units 1) must be either directly or indirectly accounted for. Since there is a large number of radionuclides in existence (>3,000), the International Commission on Radiological Protection (ICRP-107) has provided guidance on the subset of radionuclides requiring further assessment in landfills such as the E-Area LLWF. The ICRP-107 publication provides critical radiological information on 1,252 radionuclides of 97 elements. This database is the critical starting point for developing a consistent inventory limit system. SRNL-STI-2020-00174 Revision 1 vi In this new screening effort, the performance measure has been tightened up by:  Consistently looking at every exposure pathway regardless of the tier level; and  Requiring that a pathway's maximum exposure not exceed 0.1% of the applicable performance measure (e.g., 0.1% of the 4 mrem/y performance measure x 0.001 = 0.004 mrem/yr) over the entire period of performance. Bullet one ensures that no inconsistencies creep in between varying tiers such that a radionuclide passed on to the PA-level analysis would not have been first screened out at a higher level. Bullet two provides additional risk reduction in the very unlikely scenario that a set of radionuclides screened out from further consideration in a pathway would produce a cumulative dose impact approaching the applicable performance measure. In developing an overall inventory limits system a tiered approach is most efficient with respect to its acceptance and maintenance. For example, if the tracking of a significant number of radionuclides can be omitted through relatively simple, but accepted, arguments/models the overall costs are greatly reduced. The overall structure of the E-Area tiered inventory limit system is:  Tier-0-Establishment of an upper closure inventory projection  Tier-1-"NCRP-like" groundwater and intruder screening (very conservative)  Tier-2-Simple, but bounding, 1D transport modeling (conservative)  Tier-3-Generic waste (multi-D, no credit taken for any possible engineering barriers)  Tier-4-Special waste form (multi-D, credit taken for ce...

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“…A significant amount of hydraulic properties data exists for the GSA and is contained in a configuration-controlled data package (Nichols and Butcher 2020). Pertinent data from this source have been transferred into the GoldSim aquifer model.…”

Section: Material Chemical and Radionuclide Propertiesmentioning

confidence: 99%

GoldSim E-Area Low-Level Waste Facility Aquifer Zone Model Calibration Methodology

Wohlwend¹,

Hamm²

2020

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Hydraulic Properties Data Package for the E-Area Soils, Cementitious Materials, and Waste Zones - Update

Cited by 13 publications

References 64 publications

Component-In-Grout Model Implementation for the E-Area Low-Level Waste Facility's Performance Assessment

Component-In-Grout Model Implementation for the E-Area Low-Level Waste Facility's Performance Assessment

Groundwater and Intruder Radionuclide Screening

GoldSim E-Area Low-Level Waste Facility Aquifer Zone Model Calibration Methodology

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