Special Analysis for Slit Trench Disposal of the Reactor Process Heat Exchangers

Hamm, L.L.; Collard, L.B.; Aleman, S.E.; Gorensek, Maximilian B.; Butcher, T.

doi:10.2172/1043693

Cited by 6 publications

(8 citation statements)

References 5 publications

(13 reference statements)

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“…HWCTR and the HXs apply flux-to-the-water-table source terms from previous ELLWF SAs and UDQEs (Hamm et al, 2012;Hamm and Smith, 2010) [ The parameters and distributions for NRCDAs in Tables 6-43 and 6-44 account for the uncertainty in groundwater calculations (Nichols and Butcher, 2020).  I.5…”

Section: F Facility and Container Structural Stabilitymentioning

confidence: 99%

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

MAYER

Hamm

ALEMAN

et al. 2023

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SWM commissioned this SA to determine the effects of placing operational stormwater runoff covers over ST DUs ST01 through ST07 at about years 5, 10, and 15 of the 30-year operational period. Covering changed the movement of contaminants to the water table and the hypothetical well. Early movements typically decreased because the cover decreased the flow of water from the surface through the contaminants. Later movements typically increased because less of the inventory had been released than for the uncovered cases analyzed in the PA. These effects on contaminant movement translated into higher SA-calculated limits relative to PA limits in the early years and some lower SA-calculated limits relative to PA limits in the later years. Because the lower of the two sets of limits was always selected as the operational limit, the net effect was to lower limits in the later years (typically 100 years and later). Earlier covers at 5 years magnified the changes.

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Section: F Facility and Container Structural Stabilitymentioning

confidence: 99%

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

MAYER

Hamm

ALEMAN

et al. 2023

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“…Table 4-36 identifies the specific radionuclides of interest for these three SWFs. SWF model implementation in the current ELLWF PA makes use of earlier models deployed for each waste form in SAs performed by Hamm and Smith (2010), Hamm et al (2012), andFlach et al (2005) for the HWCTR, HXs, and 232-F concrete rubble, respectively (i.e., new VZ models were not developed for PA2022). HWCTR and HXs utilize the existing flux-to-the-water-table profiles provided by Hamm and Smith (2010) and Hamm et al (2012), respectively, as a source term at the water table to simulate transport through the updated GSA flow model.…”

Section: Complex Special Waste Form Conceptual Models For Trenchesmentioning

confidence: 99%

“…SWF model implementation in the current ELLWF PA makes use of earlier models deployed for each waste form in SAs performed by Hamm and Smith (2010), Hamm et al (2012), andFlach et al (2005) for the HWCTR, HXs, and 232-F concrete rubble, respectively (i.e., new VZ models were not developed for PA2022). HWCTR and HXs utilize the existing flux-to-the-water-table profiles provided by Hamm and Smith (2010) and Hamm et al (2012), respectively, as a source term at the water table to simulate transport through the updated GSA flow model. Tritium-containing concrete rubble (Figure 4-66) disposed in ST01 from the demolition of building 232-F (the old tritium facility) is the only SWF that falls in the diffusion-controlled release category.…”

Section: Complex Special Waste Form Conceptual Models For Trenchesmentioning

confidence: 99%

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

MAYER

Hamm

ALEMAN

et al. 2023

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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...

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“…Two complex special waste forms will be modeled in the next revision of the ELLWF PA: the Heavy Water Components Test Reactor (HWCTR) and the Reactor Process Heat Exchangers (HXs). The implementation will make use of models deployed for each waste form in SAs performed in 2010 (HWCTR: Hamm et al, 2010) and 2012 (HXs: Hamm et al, 2012). Each of the models that were carried out in these SAs will be re-run with adjustments made to the infiltration rates (i.e., accounting for the newly designed final closure cap) and to all input parameters that are impacted by infiltration rates such as the source and sink terms in the HXs flow model that account for lateral flow around the cylindrical shape of the heat exchangers.…”

Section: Complex Special Waste Form Model Updatesmentioning

confidence: 99%

PORFLOW Implementation of Special Waste from Models for Slit and Engineered Trenches in the E-Area Low Level Waste Facility Performance Assessment

Danielson

2020

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The implementation of special waste forms (SWFs) in the deterministic PORFLOW Slit Trench (ST) and Engineered Trench (ET) models to be used in the next revision of the E-Area Low Level Waste Facility's (ELLWFs) Performance Assessment (PA) is outlined in this report. Four SWF implementation methods will be used: effective K d , delayed release, solubility-controlled/diffusion-controlled release, and complex SWF model updates. In addition, the implementation of models that address the presence of tall used equipment storage boxes in ST08-10 is considered a special waste form and will be described. Background SWFs are a category of trench waste that exceed or consume a large fraction of the allowable inventory for specific radionuclides without taking credit for the waste form or disposal container. Additional characterization and modeling, generally performed as part of a Special Analysis (SA), are needed to produce acceptable trench disposal limits. SWF modeling incorporates chemistry, corrosion rates, hydraulics, radionuclide decay and administrative controls, as needed, to produce acceptable disposal limits through hold up or controlled release of contaminants into the backfill soil within the waste zone. Radionuclide limits treated in this manner are given a unique designation in the Waste Inventory Tracking System (WITS) to distinguish them from the equivalent "generic" radionuclide limit (i.e., limits established assuming instantaneous release of radionuclide to the surrounding backfill soil) and contribute independently to the sum-of-fractions (SOF) calculation to ensure the distribution of radionuclides in a trench are always at or below a SOF of one. SWFs are typically obtained from limited waste campaigns (e.g., deactivation and decommissioning, disposition of legacy LLW items, etc.) or are generated from site processes.

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Special Analysis for Slit Trench Disposal of the Reactor Process Heat Exchangers

Cited by 6 publications

References 5 publications

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

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

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

PORFLOW Implementation of Special Waste from Models for Slit and Engineered Trenches in the E-Area Low Level Waste Facility Performance Assessment

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