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At least 361 records · Page 20

Modelling the sulfate capacity of simulated radioactive waste borosilicate glasses

The capacity of simulated high-level radioactive waste borosilicate glasses to incorporate sulfate has been studied as a function of glass composition. Combined Raman, 57 Fe Mössbauer and literature evidence supports the attribution of coordination numbers and oxidation states of constituent cations for the purposes of modelling, and results confirm the validity of correlating sulfate incorporation in multicomponent borosilicate radioactive waste glasses with different models. A strong compositional dependency is observed and this can be described by an inverse linear relationship between incorporated sulfate (mol% SO 4 2- ) and total cation field strength index of the glass, Σ(z/a 2 ), with a high goodness-of-fit (R 2 ≈ 0.950). Similar relationships are also obtained if theoretical optical basicity, Λ th (R 2 ≈ 0.930) or non-bridging oxygen per tetrahedron ratio, NBO/T (R 2 ≈ 0.919), are used. Results support the application of these models, and in particular Σ(z/a 2 ), as predictive tools to aid the development of new glass compositions with enhanced sulfate capacities.

36 MATERIALS SCIENCE↗

Promoting Diels-Alder reactions to produce bio-BTX: Co-aromatization of textile waste and plastic waste over USY zeolite

Producing commodity aromatic hydrocarbons from textile waste is a promising approach to promote carbon neutrality and circular economy. Catalytic degradation of flax waste (FW) to generate furans and its subsequent Diels-Alder transformation to monocyclic aromatic hydrocarbons over USY zeolite were conducted. Experimental results indicated that USY catalyzed FW resulted in a 5.5-fold increase in furans production compared with the non-catalytic trial. The Si/Al molar ratio in USY played a determining role in furans formation, and a 5-fold increase was observed over USY with a Si/Al ratio of 5.3 as opposed to that with a Si/Al ratio of 11. Plastic waste, polyethylene (PE), co-fed with FW yielded 1.6 times higher aromatic hydrocarbons than polypropylene (PP). The selectivity to aromatic hydrocarbons reached 81.6% under 20% PE co-fed with 80% FW, in which benzene, toluene, and xylenes (BTX) were predominant products with the maximum selectivity of 68%. Furthermore, this study presents a cleaner approach for value-added resource recovery and sustainable management of textile and plastic waste.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Zinc-in-titania waste form for immobilizing lanthanide fission products from electrochemical reprocessing

This paper provides microstructural, microchemical, and bulk X-ray diffraction information for a zinc-in-titania waste form for immobilizing rare-earth oxide (REOx) fission products recovered through precipitation from electrochemical salt wastes. This waste form can be used to immobilize REOx at loadings as high as 40 mass% in a chemically durable matrix consisting of glass-bonded minerals including Zn2TiO4 as well as RE-containing phases of REOx, RE2Ti2O7, and REPO4 (monazite). Chemical durability data is also provided, and comparisons are drawn between this waste form and one made using a similar process with half the REOx loading.

rare earth, rare earth waste form, electrochemical↗

Artificial intelligence-driven municipal solid waste sortation and its significance on downstream waste valorization in the United States: Techno-economic and life cycle assessment

Municipal solid waste (MSW) generation is quickly increasing due to population growth, industrialization, and urbanization. Current sorting technologies, e.g., optical sorters have low sortation efficiency and produce contaminated sorted materials unsuitable for downstream valorization. This study evaluates a novel artificial neural network (ANN)-based MSW sortation system through sorting efficiencies, economic performance, and environmental impacts. ANN system can sort up to 8 plastic types and all organic waste (i.e., food, yard, and paper waste) with 99% and 93% recovery efficiency, respectively, compared to optical sortation which could separate only polyvinyl chloride (PVC) plastic ultimately producing mixed plastics (except PVC) and organics streams as products. Nonetheless, their sortation costs are similar, $28.7 for ANN-based sortation and $28 for optical sortation per metric ton (Mt) of MSW at processing capacity of 94,860 metric tons (Mt)/yr of MSW in the United States. Additionally, ANN system produced high purity feedstocks for downstream valorization. A biochar pyrolysis plant modeled to process 3.6 and 14 Mt/h of sorted yard waste outperformed biochar production from mixed organic fraction (MOF), achieving 8% lower production cost and 34% lower global warming impact (1.37 kg CO 2 eq. per kg) compared to biochar derived from mixed organic feedstock (2.08 kg CO 2 eq.).

09 BIOMASS FUELS↗

Effect of fresh green waste and green waste compost on mineral nitrogen, nitrous oxide and carbon dioxide from a Vertisol

Incorporation of organic waste amendments to a horticultural soil, prior to expected risk periods, could immobilise mineral N, ultimately reducing nitrogen (N) losses as nitrous oxide (N{sub 2}O) and leaching. Two organic waste amendments were selected, a fresh green waste (FGW) and green waste compost (GWC) as they had suitable biochemical attributes to initiate N immobilisation into the microbial biomass and organic N forms. These characteristics include a high C:N ratio (FGW 44:1, GWC 35:1), low total N (<1%), and high lignin content (>14%). Both products were applied at 3 t C/ha to a high N (plus N fertiliser) or low N (no fertiliser addition) Vertisol soil in PVC columns. Cumulative N{sub 2}O production over the 28 day incubation from the control soil was 1.5 mg/N{sub 2}O/m{sup 2}, and 11 mg/N{sub 2}O/m{sup 2} from the control + N. The N{sub 2}O emission decreased with GWC addition (P < 0.05) for the high N soil, reducing cumulative N{sub 2}O emissions by 38% by the conclusion of the incubation. Analysis of mineral N concentrations at 7, 14 and 28 days identified that both FGW and GWC induced microbial immobilisation of N in the first 7 days of incubation regardless of whether the soil environment was initially high or low in N; with the FGW immobilising up to 30% of available N. It is likely that the reduced mineral N due to N immobilisation led to a reduced substrate for N{sub 2}O production during the first week of the trial, when soil N{sub 2}O emissions peaked. An additional finding was that FGW + N did not decrease cumulative N{sub 2}O emissions compared to the control + N, potentially due to the fact that it stimulated microbial respiration resulting in anaerobic micro sites in the soil and ultimately N{sub 2}O production via denitrification. Therefore, both materials could be used as post harvest amendments in horticulture to minimise N loss through nitrate-N leaching in the risk periods between crop rotations. The mature GWC has potential to reduce N{sub 2}O, an important greenhouse gas.

54 ENVIRONMENTAL SCIENCES↗

Pilot-scale anaerobic co-digestion of municipal biomass waste and waste activated sludge in China: Effect of organic loading rate

Highlights: Black-Right-Pointing-Pointer Co-digestion of municipal biomass waste (MBW) and waste activated sludge (WAS) was examined on a pilot-scale reactor. Black-Right-Pointing-Pointer System performance and stability under OLR of 1.2, 2.4, 3.6, 4.8, 6.0 and 8.0 kg VS (m{sup 3} d){sup -1} were analyzed. Black-Right-Pointing-Pointer A maximum methane production rate of 2.94 m{sup 3} (m{sup 3} d){sup -1} was achieved at OLR of 8.0 kg VS (m{sup 3} d){sup -1} and HRT of 15d. Black-Right-Pointing-Pointer With the increasing OLRs, pH values, VS removal rate and methane concentration decreased and VFA increased. Black-Right-Pointing-Pointer The changing of biogas production rate can be a practical approach to monitor and control anaerobic digestion system. - Abstract: The effects of organic loading rate on the performance and stability of anaerobic co-digestion of municipal biomass waste (MBW) and waste activated sludge (WAS) were investigated on a pilot-scale reactor. The results showed that stable operation was achieved with organic loading rates (OLR) of 1.2-8.0 kg volatile solid (VS) (m{sup 3} d){sup -1}, with VS reduction rates of 61.7-69.9%, and volumetric biogas production of 0.89-5.28 m{sup 3} (m{sup 3} d){sup -1}. A maximum methane production rate of 2.94 m{sup 3} (m{sup 3} d){sup -1} was achieved at OLR of 8.0 kg VS (m{sup 3} d){sup -1} and hydraulic retention time of 15 days. With increasing OLRs, the anaerobic reactor showed a decrease in VS removal rate, average pH value and methane concentration, and a increase of volatile fatty acid concentration. By monitoring the biogas production rate (BPR), the anaerobic digestion system has a higher acidification risk under an OLR of 8.0 kg VS (m{sup 3} d){sup -1}. This result remarks the possibility of relating bioreactor performance with BPR in order to better understand and monitor anaerobic digestion process.

09 BIOMASS FUELS↗

Recovery of essential nutrients from municipal solid waste – Impact of waste management infrastructure and governance aspects

Every year 120–140 million tonnes of bio-waste are generated in Europe, most of which is landfilled, incinerated or stabilized and used as covering material in landfill operation. None of these practices enables the recovery of essential nutrients such as phosphorus (P) and nitrogen (N), which are in great demand for agricultural production. Recovery of these nutrients is a matter of international concern considering the non-renewable nature of P sources and the energy intensive production process required for the synthesis of N fertilizers. The objective of this research is to understand the relation between the municipal solid waste management (MSWM) system, both its the physical components and governance aspects, and the recovery of nutrients in Vitoria-Gasteiz (Basque Country) as a benchmark for European medium-size cities. The analysis shows that the existing physical infrastructure and facilities for bio-waste have high potential for nutrient recovery, 49% for N and 83% for P contained in bio-waste. However, governance aspects of the MSWM system such as legislation and user inclusivity play an important role and decrease the actual nutrient recovery to 3.4% and 7.4% for N and P respectively.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Aliphatic Amines from Waste Polyolefins by Tandem Pyrolysis, Hydroformylation, and Reductive Amination

Pyrolysis of waste plastics can produce a product mixture with a high concentration of olefins (>50 wt%). The olefins, as building blocks in the petroleum industry, are potential precursors for valuable commodity chemicals with higher values (>$2000 per ton). In this work, we produce aldehydes by hydroformylation of the olefins present in pyrolysis oil from colored post-consumer recycled high-density polyethylene (PCR-HDPE). The obtained aldehydes in the oil are then converted into aliphatic amines via reductive amination with a Ru/C catalyst. The aminated oil was characterized by multiple analytical chemistry techniques including elemental analysis, nuclear magnetic resonance spectroscopy, high-resolution liquid chromatography-mass spectrometry, and gas chromatography-mass spectrometry with a Polyarc flame ionization detector. The concentration of metals in the PCR-HDPE and oil changes during the tandem processes, showing limited effects of these elements (e.g., Al, Ca, Fe, Mg, Ti, Zn) on hydroformylation and reductive amination. Additionally, we demonstrated that reductive amination of aldehydes with varied carbon numbers and branching properties can be achieved in the presence of a complex mixture, including paraffins and aromatics. The results indicate that waste plastics have the potential to serve as a renewable source for mono and di aliphatic amines, thereby diminishing reliance on fossil feedstocks as the current primary amine source.

aliphatic amines↗

Submixture model to predict nepheline precipitation in waste glasses

Abstract High‐alumina high‐level waste ( HLW ) glasses are prone to nepheline precipitation during canister‐centerline cooling ( CCC ). If sufficient nepheline forms, the chemical durability of the glass will be significantly impacted. Overly conservative constraints have been developed and used to avoid the deleterious effects of nepheline formation in U.S. HLW glasses. The constraints used have been shown to significantly limit the loading of waste in glass at Hanford and therefore the cost and schedule of cleanup. A 90‐glass study was performed to develop an improved understanding of the impacts of glass composition on the formation of nepheline during CCC . The CCC crystallinity data from these glasses were combined with 657 glasses found in the literature. The trends showed significant effects of Na 2 O, Al 2 O 3 , SiO 2 , B 2 O 3 , CaO, Li 2 O, and potentially K 2 O on the propensity for nepheline formation. A pseudo‐ternary submixture model was proposed to identify the glass composition region prone to nepheline precipitation. This pseudo‐ternary with axes of SiO 2 + 1.98B 2 O 3 , Na 2 O + 0.653Li 2 O + 0.158CaO, and Al 2 O 3 was found to divide glasses that precipitate nepheline during CCC from those that do not. Application of this constraint is anticipated to increase the loading of Hanford high‐alumina HLW s in glass by roughly one‐third.

Vienna, John D.↗

Apatite and sodalite based glass-bonded waste forms for immobilization of 129I and mixed halide radioactive wastes

The goal of the project was to utilize the knowledge accumulated by the team, in working with minerals for chloride wastes and biological apatites, toward the development of advanced waste forms for immobilizing 129I and mixed-halide wastes. Based on our knowledge, experience, and thorough literature review, we had selected two minerals with different crystal structures and potential for high chemical durability, sodalite and CaP/PbV-apatite, to form the basis of this project. The focus of the proposed effort was towards: (i) low temperature synthesis of proposed minerals (iodine containing sodalite and apatite) leading to the development of monolithic waste forms, (ii) development of a fundamental understanding of the atomic-scale to meso-scale mechanisms of radionuclide incorporation in them, and (iii) understanding of the mechanism of their chemical corrosion, alteration mechanism, and rates. The proposed work was divided into four broad sections. deliverables. 1. Synthesis of materials 2. Materials structural and thermal characterization 3. Design of glass compositions and synthesis glass-bonded minerals, and 4. Chemical durability testing of materials.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Special Analysis for the Disposal of the Idaho National Laboratory U-233 Solidified Grinding Sludge and Associated Debris Waste Stream at the Area 5 Radioactive Waste Management Site, Nevada National Security Site, Nye County, Nevada

This special analysis report evaluates whether the Idaho National Laboratory (INL) Uranium-233 (233U) Solidified Grinding Sludge and Associated Debris waste stream is suitable for shallow land burial at the Area 5 Radioactive Waste Management Site on the Nevada National Security Site. Disposal of the INL 233U Solidified Grinding Sludge waste meets all DOE M 435.1-1 performance objectives. The INL 233U Solidified Grinding Sludge waste stream is recommended for acceptance with the condition that the total 233U inventory shall not exceed 2.3E13 Bq.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Unreviewed Disposal Question Evaluation: Disposal of the Perma-Fix Environmental Services Classified Stabilized Low-Level Waste at the Area 5 Radioactive Waste Management Site, Nevada National Security Site, Nye County, Nevada

This Unreviewed Disposal Question Evaluation assesses whether the Perma-Fix Environmental Services (PERM) Classified Stabilized Low-Level Waste (LLW) is suitable for shallow land burial at the Area 5 Radioactive Waste Management Site on the Nevada National Security Site. Disposal of the waste stream meets all performance objectives in DOE M 435.1-1, Radioactive Waste Management Manual, Chapter IV, Section P. The PERM Classified Stabilized LLW is recommended for acceptance without conditions.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

2nd Quarter Transportation Report FY2016: Waste Shipments to and from the Nevada National Security Site (NNSS), Radioactive Waste Management Complex

This report satisfies the U.S. Department of Energy, National Nuclear Security Administration Nevada Field Office commitment to prepare a quarterly summary report of waste shipments to and from the Nevada National Security Site (NNSS) Radioactive Waste Management Complex at Area 5. This report summarizes the 2nd quarter of Fiscal Year (FY) 2016 low-level radioactive waste, mixed low-level radioactive waste, and classified non-radioactive shipments. There were no shipments sent for offsite treatment and returned to the NNSS this quarter of FY2016.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Unreviewed Disposal Question Evaluation: Disposal of the Idaho National Laboratory Regulated Asbestos Low-Level Waste at the Area 5 Radioactive Waste Management Site, Nevada National Security Site, Nye County, Nevada

This Unreviewed Disposal Question Evaluation assesses whether the Idaho National Laboratory (INL) Regulated Asbestos Low-Level Waste (LLW) is suitable for shallow land burial at the Area 5 Radioactive Waste Management Site on the Nevada National Security Site. Disposal of the waste stream meets all performance objectives in DOE M 435.1-1, Radioactive Waste Management Manual, Chapter IV, Section P. The INL Regulated Asbestos LLW is recommended for acceptance without conditions.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Impact of Permanganate Oxidation of Glycolate on Corrosion of the Defense Waste Processing Facility (DWPF) Recycle Collection Tank (RCT), Transfer-line and Waste Tank Materials of Construction (MoC)

Savannah River Remediation (SRR) is evaluating the use of glycolic acid to replace formic acid as an alternate reductant for the Defense Waste Processing Facility (DWPF) at Savannah River Site (SRS). The replacement is aimed at reducing facility hazards, improving pH stability and rheological control, and lowering off gas production. Glycolate, which is the product that may remain, can also be carried downstream to High-Level Waste and Low-Level Waste facilities. Complete oxidation of glycolate and other organic species from the Sludge Receipt and Adjustment Tank (SRAT) may be necessary to minimize thermolytic hydrogen generation that can cause flammability issues. The glycolate oxidation may be performed in the Recycle Collection Tank (RCT). The RCT heel would be adjusted with sodium hydroxide to maintain the solution caustic and sodium nitrite as corrosion inhibitor prior to the addition of condensate that can be from the contents of the Slurry Mix Evaporator Condensate Tank (SMECT) or Offgas Condensate Tank (OGCT). The RCT tank collects the waste to be transferred via the Low Point Pump Pit – Recycle Pump Tank (LPPP-RPT) through a jacketed transfer-line to the Tank Farm facility. Scoping studies were performed to evaluate an oxidizing agent and sodium permanganate was selected as the best option for glycolate destruction. Testing was recommended to determine the impact on the Materials of Construction (MoC) due to the addition of sodium permanganate. The targeted concentration of sodium permanganate used equated to a 7:1 molar permanganate to glycolate ratio (nominally 0.002 M permanganate). However, to conservatively maximize the permanganate corrosivity, in some cases no glycolate was added.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Unreviewed Disposal Question Evaluation: Disposal of the West Valley Demonstration Project Asbestos Contaminated Low-Level Waste Debris at the Area 5 Radioactive Waste Management Site, Nevada National Security Site, Nye County, Nevada

This Unreviewed Disposal Question Evaluation assesses whether the West Valley Demonstration Project (WVDP) Asbestos Contaminated Low-Level Waste (LLW) Debris is suitable for shallow land burial at the Area 5 Radioactive Waste Management Site on the Nevada National Security Site. Disposal of the WVDP Asbestos Contaminated LLW Debris meets all performance objectives in DOE M 435.1-1, “Radioactive Waste Management Manual,” Chapter IV, Section P. The WVDP Asbestos Contaminated LLW Debris is recommended for acceptance with the condition that the total radium-226 (226Ra) waste stream activity shall not exceed 2E+9 Bq.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Evaluation of Degradation Mechanisms for Solid Secondary Waste Grout Waste Forms

The overall objective of this work is to provide defensibility for the long-term performance of grouted Hanford SSW streams when disposed in a near surface disposal facility, IDF, on the Hanford Site. Providing defensibly for the long-term performance of the grouted waste forms is consistent with the research and development activities identified in the Performance Assessment Maintenance Plan, (Westcott et al. 2019), that are necessary to address the assumptions made in the PA. Specifically, this work addresses two areas identified for further research and development activities in the plan: (1) “Evaluate ongoing research on transport characteristics of cementitious materials using accelerated tests to approximate the effects of aging/alteration/weathering”; and (2) “Evaluate ongoing research on microbial effects on transport processes in cementitious materials.” The assembled subject matter expert team evaluated a list of degradation mechanisms and supporting processes and provided rankings of areas where further research and development (R&D) are needed. From this assessment, high priority R&D areas include: (1) the effects of carbonation, Ca leaching, and SSW dimensional change in grout waste forms; (2) updated model representations of grouted waste forms; and (3) scaled testing demonstrations. Moderate priority items including a paper study on possible microbial influence, reoxidation rates, radionuclide/contaminant dissolution from SSW in the grout and freeze thaw behavior. Other processes evaluated were either deemed unlikely to occur, to have little impact on the SSW waste forms, or to occur at time frames beyond those considered (>10,000 years). The assessments and proposed R&D approaches are expected to support an update to the WRPS SSW roadmap.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Evaluating High-Halide Waste Form Options for Salt-Based Nuclear Waste Simulants

In this study, waste forms were being explored for an electrochemical salt simulant, , referred to as ERV3, which is a high-LiCl/KCl salt containing simulated fission products (i.e., Sr, Cs, Nd) and Na to represent bond sodium from Experimental Breeder Reactor-II metallic fast reactor fuel. The goal was to find glassy systems that could be used to immobilize the salt in a single-step process. The envisionment of this process would be find a frit glass that could be added to the salt waste, heat treated, poured into waste canisters, and then stored for disposal. To perform this study, a literature review was conducted, the most promising seven systems were fabricated without the salt, and then mixed with salt simulant and heat treated under different processes. The criteria that were used to screen potential compositions included demonstrated alkali incorporation, could be melted at reasonably low temperature ( T ≤ 1000°C), and if the compositions had some demonstrated data for waste-form-related properties, that was a benefit. High marks were given for compositions that showed amorphous nature after slow cooling of samples containing ERV3.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗