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At least 19 records

Identification of Potential Waste Processing and Waste Form Options for Molten Salt Reactors

The overall summary of the waste management envelope discussed in this report is represented by the diagram shown in Figure S1. The streams that are included in this discussion include the following from reactor systems in which chlorine-based salts with and without processing and fluorine-based salts with and without processing are being considered: 1) Off-gas streams (e.g., particulates, aerosols, reactive gases, 3 H, water, residual halides, N 2 , O 2 , noble gases); 2) Salt waste streams (e.g., chloride- or fluoride-based); 3) Separated salt streams (e.g., 7 Li recycle, 37 Cl recycle, eutectic salts, fission products); 4) Metal waste streams (e.g., reactor components, plenums); 5) Carbon waste streams (e.g., graphite, SiC); 6) Decommissioning and decontaminating (D&D) waste streams; 7) Operating waste streams

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Saltstone Waste Characterization Analysis - Salt Waste Processing Facility (SWPF) Waste Stream (Q4 CY2020)

The Saltstone Production and Disposal Facility is designed and permitted by the state of South Carolina Department of Health and Environmental Control (SCDHEC) to treat and dispose of low-level radioactive and hazardous liquid waste (salt solution) remaining from the processing of radioactive material at the Savannah River Site (SRS). Low-level waste (LEW) aqueous streams from the Effluent Treatment Project (ETP) and decontaminated solutions from the Tank Closure Cesium Removal Unit (TCCR) and the Salt Waste Processing Facility (SWPF) are stored in Tank 50 until the LEW can be transferred to the Saltstone Facility for treatment and disposal. In the past, decontaminated solution from the Modular Caustic Side Solvent Extraction Unit (MCU) was stored in Tank 50 until the LEW could be transferred to the Saltstone Facility for treatment and disposal. MCU is currently in a suspended operations state. LEW that meets the Waste Acceptance Criteria (WAC) can be transferred, stored, and treated in the Saltstone Production Facility (SPF) for subsequent disposal as saltstone grout in the Saltstone Disposal Facility (SDF). Sampling will be conducted as new waste streams are identified for treatment and disposal at the Saltstone Industrial Wastewater Treatment Facility (IWTF) and Z-Area Industrial Solid Waste Landfill (ISWLF), Facility ID# 025500-1603, General Condition B.9 or every six years in accordance with South Carolina (SC) Regulation 61-107.19 Parti C, “Solid Waste Management: Solid Waste Landfills and Structural Fill - General Requirements.”

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UNREVIEWED DISPOSAL QUESTION EVALUATION: Disposal of the TRU Waste Processing Center Mixed Low Level Waste at the Area 5 Radioactive Waste Management Site, Nevada National Security Site, Nye County, Nevada

This Unreviewed Disposal Question Evaluation (UDQE) assesses whether the U.S. Department of Energy (DOE), National Nuclear Security Administration (NNSA) Transuranic (TRU) Waste Processing Center Mixed Low Level Waste (MLLW), FWORCHMLLW103, Revision 13 [TWPC 2021]), is suitable for shallow land burial (SLB) at the Area 5 Radioactive Waste Management Site (RWMS) on the Nevada National Security Site (NNSS). Disposal of the TRU Waste Processing Center MLLW meets all performance objectives of DOE Manual DOE M 435.1-1, Radioactive Waste Management Manual, Chapter IV, Section P (DOE 1999). The TRU Waste Processing Center MLLW waste stream is recommended for acceptance without conditions.

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Preliminary evaluation of waste processing in a CELSS

Physical/chemical, biological, and hybrid methods can be used in a space environment for processing wastes generated by a Closed Ecological Life Support System (CELSS). Two recycling scenarios are presented. They reflect differing emphases on and responses to the waste system formation rates and their composition, as well as indicate the required products from waste treatment that are needed in a life support system.

Jacquez, Ricardo B.↗

UNREVIEWED DISPOSAL QUESTION EVALUATION: Disposal of the Transuranic Waste Processing Center Low-Level Waste at the Area 5 Radioactive Waste Management Site, Nevada National Security Site, Nye County, Nevada

This Unreviewed Disposal Question Evaluation (UDQE) assesses whether the Transuranic Waste Processing Center (TWPC) Low-Level Waste (LLW), FWORCHLLW0102, Revision 12 (TWPC 2021), is suitable for shallow land burial (SLB) at the Area 5 Radioactive Waste Management Site (RWMS) on the Nevada National Security Site (NNSS). Disposal of the TWPC LLW meets all performance objectives of DOE Manual DOE M 435.1-1, Radioactive Waste Management Manual, Chapter IV, Section P (DOE 1999). The TWPC LLW waste stream is recommended for acceptance without conditions.

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Implementation of the Glycolate Destruction Process with Sodium Permanganate in the Defense Waste Processing Facility (DWPF) - 20141

The Savannah River Site (SRS) seeks to replace formic acid with glycolic acid as a chemical reductant in the Defense Waste Processing Facility (DWPF), where borosilicate glass is mixed with high-level radioactive waste, melted at high temperatures, then poured into stainless steel canisters for safe storage. Prior research and development have demonstrated the feasibility and advantages of the new nitric-glycolic acid flowsheet over the current nitric-formic acid flowsheet to chemically adjust the radioactive sludge slurry waste in the Sludge Receipt and Adjustment Tank (SRAT) prior to vitrification. Use of glycolic acid reduces hydrogen and ammonia generation during the reduction process, thus reducing flammability hazards and purge requirements in the DWPF processing vessels. In addition, glycolic acid will support the new Salt Waste Processing Facility (SWPF) by allowing for receipt of higher volumes of waste due to reduction of flammable gases, increased boil-up rates in the vessels, and easing the processing of future sludge batches containing high levels of mercury. However, during DWPF operations, trace amounts of glycolate are anticipated to be entrained in the recycle stream and sent to the Concentration, Storage, and Transfer Facilities (CSTF) via the Recycle Collection Tank (RCT). The RCT receives condensate from the Slurry Mix Evaporator Condensate Tank (SMECT) and Off-gas Condensate Tank (OGCT) that may contain unreacted glycolate. A literature review found the potential for hydrogen generation due to thermolysis of glycolate in caustic CSTF conditions. Savannah River National Laboratory (SRNL) conducted several tests on simulant and radioactive waste from various tanks at SRS and confirmed that glycolate added to waste at concentrations of approximately 1000 mg/L and higher generates hydrogen through thermolysis. There are potential operating scenarios in the future where glycolate concentration could exceed 1000 mg/L in the 2H Evaporator Drop Tank, the highest accumulation point for DWPF organics received via recycle. These findings presented a need to develop another process to mitigate the impact of glycolic acid to the CSTF. Several DWPF compatible options were evaluated for their ability to destroy glycolate in the DWPF recycle stream under various processing conditions, thereby mitigating its introduction to the CSTF. Downselection testing identified sodium permanganate as the most promising and simplest option to oxidize glycolate. It has been demonstrated to be effective in various RCT simulant compositions, operating temperatures, oxidant addition rates, solution pH, and initial glycolate concentrations. A feasibility study identified existing tanks within the facility that could be used for receiving and storing the commercially available sodium permanganate, as well as feeding it to the RCT for processing. The use of existing equipment as well as the ability to purchase the pre-mixed chemical reduces implementation and operational complexity. The downstream impacts of the sodium permanganate reaction were also evaluated and demonstrated to have minimal impact on other chemical species present in the RCT and CSTF, as well as on the materials of construction of the RCT and CSTF vessels and associated piping and instrumentation. Future work is in progress to validate the glycolate destruction process with testing in actual radioactive RCT waste before implementation in DWPF. (authors)

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Alternative Processes for Water Reclamation and Solid Waste Processing in a Physical/chemical Bioregenerative Life Support System

Viewgraphs on alternative processes for water reclamation and solid waste processing in a physical/chemical-bioregenerative life support system are presented. The main objective is to focus attention on emerging influences of secondary factors (i.e., waste composition, type and level of chemical contaminants, and effects of microorganisms, primarily bacteria) and to constructively address these issues by discussing approaches which attack them in a direct manner.

Rogers, Tom D.↗

Unreviewed Disposal Question Evaluation: Disposal of the Transuranic Waste Processing Center Mixed Low-Level Waste at the Area 5 Radioactive Waste Management Site, Nevada National Security Site, Nye County, Nevada

This Unreviewed Disposal Question Evaluation (UDQE) assesses whether the Transuranic Waste Processing Center (TWPC) Mixed Low-Level Waste (MLLW) (FWORCHMLLW103, Revision 11 [TWPC 2018]) is suitable for shallow land burial (SLB) at the Area 5 Radioactive Waste Management Site (RWMS) on the Nevada National Security Site (NNSS). Disposal of the TWPC MLLW waste stream meets all performance objectives of U.S. Department of Energy (DOE) Manual DOE M 435.1-1, Radioactive Waste Management Manual, Chapter IV, Section P (DOE 1999). The TWPC MLLW waste stream is recommended for acceptance without conditions.

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Oxidation of Organics in the Defense Waste Processing Facility Condensate

Defense Waste Processing Facility (DWPF): The state of South Carolina currently holds 35 million gallons of radioactive waste in 51 underground tanks. DWPF was built in an effort to convert the waste into a more stable form. It turns the sludge waste from the tanks into glass, which will keep the waste stable for 10,000 years. Currently, DWPF uses formic acid in its flowsheet and there is one major problem associated with its use: it decomposes into hydrogen, a flammable gas. Glycolic acid, however, has been found as a possible alternative that performs similarly to formic acid but does not directly form hydrogen. One of the main issues with the glycolic acid flowsheet is the potential for there to be glycolate and other organics in DWPF's Recycle Collection Tank (RCT). These organics could lead to hydrogen generation later in the downstream evaporators and must be destroyed in the RCT in order for glycolic acid to be a suitable replacement for formic acid. Oxidants can be added to the RCT to destroy the organics. Two oxidizers, permanganate and Fenton's reagent (iron catalyzed hydrogen peroxide), are possible candidates. Find optimum processing conditions for the oxidation of organic species in a typical RCT simulant. A reactor served as a small-scale version of the RCT. During each run, an RCT simulant with 8 added organics, including glycolate, was created in the reactor. Either permanganate or peroxide was slowly added for each run through a syringe pump. Each experiment lasts 6 hours and a total of 23 runs are scheduled. Variables of Interest: Oxidizer (Permanganate or Peroxide); Temperature (15 deg. C to 50 deg. C); Oxidant addition time (10 mins to 2 hours); Amount of oxidant (1 x to 1.5 x stoichiometric requirements); Solution pH (3 to 13); Glycolate concentration (125 to 250 mg/kg). Offgas Analyzers: Mass spectrometer and FTIR spectrometer. Samples: pulled at 7 different times throughout the run to determine the amount of organic and inorganic carbon and concentrations of various organics through ion chromatography (IC). Only 3 of the runs have been completed at this point, all with permanganate. Based on the first 3 runs, permanganate seems to oxide the majority of the organics and the run at pH 8 and 32.5 deg. C had the most effective oxidation. The rest of the runs will need to be performed to determine the best oxidant and optimum values of the other variables of interest. Once the experiment is completed, DWPF will select one of the oxidants. Testing will continue to determine its performance during foam-over and other non-ideal conditions. Finally, the oxidant will be tested with actual radioactive waste to confirm its effectiveness.

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Alternative Treatment of Defense Waste Processing Facility Recycle via Reuse of Existing Liquid Waste Facilities - 20097

The Defense Waste Processing Facility (DWPF) at Savannah River Site (SRS) has been immobilizing high level waste since 1996. The chemical process within DWPF generates a large volume of condensate, which is recycled to the SRS H-Area Tank Farm. The recycle stream includes a small quantity of sludge solids, as well as soluble cesium that is volatilized during melter operation. The recycle waste is currently received into a large, underground waste tank that separates insoluble solids via decanting. The supernate is treated by an evaporator with a concentrate stream that is stored for future processing. The evaporator overheads are collected and sent to the Effluent Treatment Project (ETP) for final polishing and testing prior to discharge to local surface water. Recycle storage and treatment as described above complicates the overall mission within the tank farms, which are primarily engaged in waste retrieval and preparation activities that support sludge and salt disposition, as well as tank characterization and closure. The need to devote a portion of available storage space to recycle treatment limits operational flexibility, and ultimately the DWPF recycle stream must be diverted to fully close all the SRS waste tanks. An alternative treatment process is being explored to decouple the recycle stream from the tank farm. The proposed treatment process will accomplish solids separation via crossflow filtration and will utilize a wiped film evaporator to volume-reduce the filtrate stream. Evaporator overheads will continue to be further processed in ETP while the solids stream and evaporator concentrate stream will be returned for reprocessing with the DWPF and Salt Waste Processing Facility (SWPF). This process will utilize existing facilities within DWPF and the tank farm that were previously dedicated to Interim Salt Disposition (ISD), but no longer have an identified mission with the startup of SWPF. The reuse of these facilities will remove several constraints from the current Liquid Waste (LW) System Plan without expanding the current footprint of Department of Energy Environmental Management (EM) infrastructure within LW. (authors)

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A U-bearing composite waste form for electrochemical processing wastes

Metallic/ceramic composite waste forms are being developed to immobilize combined metallic and oxide waste streams generated during electrochemical recycling of used nuclear fuel. Composites were made for corrosion testing by reacting HT9 steel to represent fuel cladding, Zr and Mo to simulate metallic fuel waste, and a mixture of ZrO2, Nd2O3, and UO2 to represent oxide wastes. More than half of the added UO2 was reduced to metal and formed Fe-Zr-U intermetallics and most of the remaining UO2 and all of the Nd2O3 reacted to form zirconates. Fe-Cr-Mo intermetallics were also formed. Microstructure characterization of the intermetallic and ceramic phases that were generated and tests conducted to evaluate their corrosion behaviors indicate composite waste forms can accommodate both metallic and oxidized waste streams in durable host phases. (c) 2018 Elsevier B.V. All rights reserved.

Chen, X. (ORCID:0000000332734431)↗

Distribution of human waste samples in relation to sizing waste processing in space

Human waste processing for closed ecological life support systems (CELSS) in space requires that there be an accurate knowledge of the quantity of wastes produced. Because initial CELSS will be handling relatively few individuals, it is important to know the variation that exists in the production of wastes rather than relying upon mean values that could result in undersizing equipment for a specific crew. On the other hand, because of the costs of orbiting equipment, it is important to design the equipment with a minimum of excess capacity because of the weight that extra capacity represents. A considerable quantity of information that had been independently gathered on waste production was examined in order to obtain estimates of equipment sizing requirements for handling waste loads from crews of 2 to 20 individuals. The recommended design for a crew of 8 should hold 34.5 liters per day (4315 ml/person/day) for urine and stool water and a little more than 1.25 kg per day (154 g/person/day) of human waste solids and sanitary supplies.

Parker, Dick↗

Pseudo-dynamic Aspen Plus{sup R} Model of the Defense Waste Processing Facility - 18475

The Defense Waste Processing Facility (DWPF) at the Savannah River Site converts legacy high-level waste from the Cold War into borosilicate glass for permanent disposal in a geological repository. The waste sludge is chemically adjusted by the addition of acid, mixed with frit, and concentrated in the DWPF Chemical Process Cell (CPC) to ensure that the final glass has the desired properties. The resulting mixture is fed into the melter where the waste is melted and poured into stainless steel storage canisters. We present an Aspen Plus{sup R} model of the DWPF CPC, which is being developed to aid chemical processing decisions pertaining to the current flowsheet and to aid decisions regarding optimizing future processing. Given a waste feed composition with acid and frit additions, the model will predict the sludge and off-gas compositions throughout the processing, as well as the final melter feed composition. This allows different processing scenarios to be investigated easily, reducing the reliance on experimental testing, and hence saving time and money. The model has multiple potential applications, including calculating the acid and frit additions required to give acceptable glass properties, off-gas permitting, tracking mercury steam-stripped from the waste in the off-gas system, tracking flammable gases in the offgas system, investigating the effect of reducing air purges in the condensers, and general process optimization. The waste is processed in the CPC in batches, requiring dynamic simulation to track the time-dependent operations. Accurate modeling of the processing also requires calculations of phase and electrolyte chemical equilibria and parallel rate-dependent reactions. Due to existing technical limitations with dynamic simulation of the complex chemical system, we have adopted a pseudo-dynamic approach in which time intervals are treated as consecutive steady-state operations in Aspen Plus{sup R}. Thus, the model consists of ∼100 replicas of the processing vessel and its off-gas system, with the sludge output by one replica (representing one time interval) becoming the feed to the next (representing the next time interval). By examining the results from these replicas in sequence, one can see the time evolution of the model. This general approach can be used wherever simultaneous calculation of phase and electrolyte chemical equilibria in a dynamically evolving system is needed. In addition to describing the general structure and chemistry of the model, we present results from tests of the model against experimental data. These data are from laboratory-scale process simulations of the CPC with a nonradioactive waste sludge simulant. These tests include the model's predictions of the offgas composition, the sludge pH, and the final sludge composition. We will also discuss planned future developments of the model. (authors)

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Historical Scaling Performance from Laboratory to Full Scale for The Defense Waste Processing Facility's Chemical Process Cell

The Defense Waste Processing Facility (DWPF) is planning to modify the chemical processing flowsheet by replacing formic acid with glycolic acid in the Chemical Process Cell (CPC) Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME). The replacement of formic acid with glycolic acid virtually eliminates the CPC’s largest flammability hazards, catalytic hydrogen and ammonia.

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Bioregenerative technologies for waste processing and resource recovery in advanced space life support system

The Controlled Ecological Life Support System (CELSS) for producing oxygen, water, and food in space will require an interactive facility to process and return wastes as resources to the system. This paper examines the bioregenerative techologies for waste processing and resource recovery considered for a CELSS Resource Recovery system. The components of this system consist of a series of biological reactors to treat the liquid and solid material fractions, in which the aerobic and anaerobic reactors are combined in a block called the Combined Reactor Equipment (CORE) block. The CORE block accepts the human wastes, kitchen wastes, inedible refractory plant materials, grey waters from the CELLS system, and aquaculture solids and processes these materials in either aerobic or anaerobic reactors depending on the desired product and the rates required by the integrated system.

Chamberland, Dennis↗

Evaluation of the Sludge Batch 9-Frit 803 Variability Study Glasses with the Revised Defense Waste Processing Facility Product Composition Control System

Compositionally, Sludge Batch 8 (SB8) and Sludge Batch 9 (SB9) are similar. Frit 803 was developed for SB8, and was subsequently confirmed for SB9 processing at a waste loading target of 36% ± 4 percentage points. The SB9 – Frit 803 experimental variability study was issued in 2016. Durability measurements from these glasses were assessed to demonstrate the applicability of the Defense Waste Processing Facility (DWPF) Product Composition Control System (PCCS) durability models for the SB9 – Frit 803 glass system, and the acceptability of the glasses with respect to the Environmental Assessment glass in terms of durability, as defined by Product Consistency Test (PCT).

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Characterization of Precipitate Reactor Feed Tank (PRFT) Batches 15, 22, and 26 from the Defense Waste Processing Facility (DWPF)

The Savannah River Site (SRS) Defense Waste Processing Facility (DWPF) processes a Monosodium Titanate/Sludge Solids (MST/SS) waste stream received from the Salt Waste Processing Facility (SWPF) via the Precipitate Reactor Feed Tank (PRFT). During processing, DWPF is required to provide evidence of compliance with the Waste Acceptance Product Specifications (WAPS) to ensure acceptance of their vitrified high-level waste (HLW) into the Civilian Radioactive Waste Management System. Production Records must document the constituents of the MST/SS material in the PRFT from each salt batch (StB) processed at SWPF. Savannah River Mission Completion (SRMC) has requested Savannah River National Laboratory (SRNL) to analyze PRFT samples representing each SWPF salt batch for thirty-two radionuclides. Additionally, elemental analysis of PRFT slurry and MST/SS solids was performed to aid SRMC in further refinement of the inputs and assumptions used in future frit development and Material Tracking Program calculations. The analyses of PRFT Batches 15, 22, and 26, which corresponds to material from the processing of StB4, StB5, and StB7, respectively, are reported herein. The unwashed dried solids of the PRFT batches were found to be 86-87% MST. Additionally, the total sulfur values are well below the assumed 982 mg of sulfate/kg of PRFT slurry used in Material Tracking Program calculations.

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