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Project update on Performance Testing to Advance Modular, Moving-Bed Gasification for the Generation of Low-Cost, Clean Hydrogen from Biomass Mixed with Legacy Coal Waste, Waste Plastic, and/or Other Waste
Immobilization of radioiodine (e.g., 129I, 131I) is an important need for current and future nuclear fuel cycles. For the current work, iodosodalite [Na8(AlSiO4)6I2] was synthesized hydrothermally from metakaolin, NaI, and NaOH. Following hydrothermal treatment, dried unwashed powders were used to make glass-bonded iodosodalite waste forms by heating pressed pellets at 650, 750, or 850 °C with two different types of sodium borosilicate glass binders, i.e., NBS-4 and SA-800. These heat-treated specimens were characterized with X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, thermal analysis, porosity and density measurements, neutron activation analysis, and inductively-coupled plasma mass spectrometry. The pellets mixed with 10 mass% of NBS-4 or SA-800 and heat-treated at 750 °C contained relatively high percentage iodine retention (~44-47 % of the maximum iodine loading) with relatively low porosities, while other pellets with higher percentages iodine retention either contained higher porosity or were not completely sintered. ASTM C1308 chemical durability tests of monolithic specimens showed a large initial release of Na, Al, Si, and I on the first day, possibly from water-soluble salt crystals or non-durable amorphous phases. Release rates of Na and Si were higher than for Al and I, probably due to a poorly durable Na-Si-O phase from the glass bonding matrix. The cumulative normalized release of iodine was 12.5 g m-2 for the first 10 1-d exchanges, suggestive of coherent dissolution. The average release rate from 10-24 days during the 7-d exchange intervals was 0.2336 g m-2 d-1.
Highlights: • Drying model for a high salt content cementitious waste form is developed. • Water vapor diffusion and capillary liquid flow are distinguished. • Capillary and salt solution effects are considered in vapor-liquid equilibrium. A water transport model coupling capillary liquid flow with vapor diffusion is developed to describe the drying process for a cementitious waste form with high salinity porewater. Vapor-liquid equilibrium is formulated as the driving force for vapor diffusion and the model accounts for pore capillary and high salinity effects on water thermodynamic activity. Pore filling and porewater surface tension as a function of pore size distribution and water saturation have been quantified for the material. Geochemical speciation modeling is used to simulate porewater activity as a function of composition over the range of saturation. The theoretical relationship between relative humidity and water saturation generally agrees with experimental measurement, and the developed model is capable of predicting drying rates under various external relative humidity conditions. The model was developed to be incorporated into reactive transport models considering the effects of drying such as salt redistribution and efflorescence.
The behavior of non-pertechnetate (Tc(I)) species was studied by preparing three portions of dried low-activity waste-glass simulated feed, combining it with either the [fac-Tc(CO) (OH)] “tetramer,” the [fac-Tc(CO) (OH)(H O) ] “monohydroxo,” or the [fac-Tc(CO) Cl ] “trichloro,” and then heating samples to 600, 800, and 1000 °C. For the feeds and the heat-treated samples, Tc concentrations were measured by liquid scintillation counting (LSC) after NaOH and HNO fusion, and the results were used to determine the Tc volatility. For unheated samples and samples heated to 600 °C, the speciation of Tc was measured by X-ray absorption near-edge structure (XANES) analysis, while partitioning of Tc in the glass-forming melt was determined by leaching the samples in water and measuring the Tc concentration of the leachate. The current results are discussed in connection with previously reported data for Tc(VII) and Tc(IV) species to rationalize the potential mechanism on how different speciation of Tc affect its retention in glass. 3 4 3 2 2 3 3 3 2-
Hydrothermal liquefaction (HTL) is a viable thermochemical process for converting wet solid wastes into biocrude which can be hydroprocessed to liquid transportation fuel blendstocks and specialty chemicals. The aqueous byproduct from HTL contains significant amounts (20 to 50%) of the feed carbon, which must be used to enhance economic sustainability of the process on an industrial scale. In this study, aqueous fractions produced from HTL of industrial and municipal waste were characterized using a wide variety of analytical approaches. Organic chemical compounds present in these aqueous fractions were identified using two-dimensional gas chromatography equipped with time-of-flight mass spectrometry. Identified compounds include organic acids, nitrogen compounds, alcohols, aldehydes, and ketones. Conventional gas chromatography and liquid chromatography methods were employed to quantify the identified compounds. Inorganic species, in the aqueous stream of hydrothermal liquefaction of these aqueous byproducts, also were quantified using ion chromatography and inductively coupled plasma optical emission spectroscopy. The concentrations of organic chemical compounds and inorganic species are reported, and the significance of these results is discussed in detail.
Apatite-structured materials have been considered for immobilization of a number of fission products from reprocessing nuclear fuel because of their chemical durability as well as compositional and structural flexibility
The NTS solid waste disposal sites must be permitted by the state of Nevada Solid Waste Management Authority (SWMA). The SWMA for the NTS is the Nevada Division of Environmental Protection, Bureau of Federal Facilities (NDEP/BFF). The U.S. Department of Energy's National Nuclear Security Administration Nevada Site Office (NNSA/NSO) as land manager (owner), and National Security Technologies (NSTec), as operator, will store, collect, process, and dispose all solid waste by means that do not create a health hazard, a public nuisance, or cause impairment of the environment. NTS disposal sites will not be included in the Nye County Solid Waste Management Plan. The NTS is located approximately 105 kilometers (km) (65 miles [mi]) northwest of Las Vegas, Nevada (Figure 1). The U.S. Department of Energy (DOE) is the federal lands management authority for the NTS, and NSTec is the Management and Operations contractor. Access on and off the NTS is tightly controlled, restricted, and guarded on a 24-hour basis. The NTS has signs posted along its entire perimeter. NSTec is the operator of all solid waste disposal sites on the NTS. The Area 5 RWMS is the location of the permitted facility for the Solid Waste Disposal Site (SWDS). The Area 5 RWMS is located near the eastern edge of the NTS (Figure 2), approximately 26 km (16 mi) north of Mercury, Nevada. The Area 5 RWMS is used for the disposal of low-level waste (LLW) and mixed low-level waste. Many areas surrounding the RWMS have been used in conducting nuclear tests. A Notice of Intent to operate the disposal site as a Class III site was submitted to the state of Nevada on January 28, 1994, and was acknowledged as being received in a letter to the NNSA/NSO on August 30, 1994. Interim approval to operate a Class III SWDS for regulated asbestiform low-level waste (ALLW) was authorized on August 12, 1996 (in letter from Paul Liebendorfer to Runore Wycoff), with operations to be conducted in accordance with the ''Management Plan for the Disposal of Low-Level Waste with Regulated Asbestos Waste.'' A requirement of the authorization was that on or before October 9, 1999, a permit was required to be issued. Because of NDEP and NNSA/NSO review cycles, the final permit was issued on April 5, 2000, for the operation of the Area 5 Low-Level Waste Disposal Site, utilizing Pit 7 (P07) as the designated disposal cell. The original permit applied only to Pit 7, with a total design capacity of 5,831 cubic yards (yd{sup 3}) (157,437 cubic feet [ft{sup 3}]). NNSA/NSO is expanding the SWDS to include the adjacent Upper Cell of Pit 6 (P06), with an additional capacity of 28,037 yd{sup 3} (756,999 ft{sup 3}) (Figure 3). The proposed total capacity of ALLW in Pit 7 and P06 will be approximately 33,870 yd{sup 3} (0.9 million ft{sup 3}). The site will be used for the disposal of regulated ALLW, small quantities of low-level radioactive hydrocarbon-burdened (LLHB) media and debris, LLW, LLW that contains PCB Bulk Product Waste greater than 50 ppm that leaches at a rate of less than 10 micrograms of PCB per liter of water, and small quantities of LLHB demolition and construction waste (hereafter called permissible waste). Waste containing free liquids, or waste that is regulated as hazardous waste under the Resource Conservation and Recovery Act (RCRA) or state-of-generation hazardous waste regulations, will not be accepted for disposal at the site. The only waste regulated under the Toxic Substances Control Act (TSCA) that will be accepted at the disposal site is regulated asbestos-containing materials (RACM). The term asbestiform is used throughout this document to describe this waste. Other TSCA waste (i.e., polychlorinated biphenyls [PCBs]) will not be accepted for disposal at the SWDS. The disposal site will be used as a depository of permissible waste generated both on site and off site. All generators designated by NNSA/NSO will be eligible to dispose regulated ALLW at the Asbestiform Low-Level Waste Disposal Site in accordance with the U.S. Department of Energy, Nevada Operations Office (DOE/NV) 325, Nevada Test Site Waste Acceptance Criteria (NTSWAC, current revision). Approval will be given by NNSA/NSO to generators that have successfully demonstrated through process knowledge (PK) and/or sampling and analysis that the waste is low-level, contains asbestiform material, and does not contain prohibited waste materials. Each waste stream will be approved through the Radioactive Waste Acceptance Program (RWAP), which ensures that the waste meets acceptance requirements outlined in the NTS Class III Permit and the NTSWAC.
To support the selection of a waste form for the liquid secondary wastes from WTP, Washington River Protection Solutions has initiated secondary-waste-form testing work at Pacific Northwest National Laboratory (PNNL). In anticipation of a down-selection process for a waste form for the Solidification Treatment Unit to be added to the ETF, PNNL is conducting tests on four candidate waste forms to evaluate their ability to meet potential waste acceptance criteria for immobilized secondary wastes that would be placed in the IDF. All three waste forms demonstrated compressive strengths above the minimum 3.45 MPa (500 psi) set as a target for cement-based waste forms. Further, none of the waste forms showed any significant degradation in compressive strength after undergoing thermal cycling (30 cycles in a 10 day period) between -40 C and 60 C or water immersion for 90 days. The three leach test methods are intended to measure the diffusion rates of contaminants from the waste forms. Results are reported in terms of diffusion coefficients and a leachability index (LI) calculated based on the diffusion coefficients. A smaller diffusion coefficient and a larger LI are desired. The NRC, in its Waste Form Technical Position (NRC 1991), provides recommendations and guidance regarding methods to demonstrate waste stability for land disposal of radioactive waste. Included is a recommendation to conduct leach tests using the ANS 16.1 method. The resulting leachability index (LI) should be greater than 6.0. For Hanford secondary wastes, the LI > 6.0 criterion applies to sodium leached from the waste form. For technetium and iodine, higher targets of LI > 9 for Tc and LI > 11 for iodine have been set based on early waste-disposal risk and performance assessment analyses. The results of these three leach tests conducted for a total time between 11days (ASTM C1308) to 90 days (ANS 16.1) showed: (1) Technetium diffusivity: ANSI/ANS 16.1, ASTM C1308, and EPA 1315 tests indicated that all the waste forms had leachability indices better than the target LI > 9 for technetium; (2) Rhenium diffusivity: Cast Stone 2M specimens, when tested using EPA 1315 protocol, had leachability indices better than the target LI > 9 for technetium based on rhenium as a surrogate for technetium. All other waste forms tested by ANSI/ANS 16.1, ASTM C1308, and EPA 1315 test methods had leachability indices that were below the target LI > 9 for Tc based on rhenium release. These studies indicated that use of Re(VII) as a surrogate for 99Tc(VII) in low temperature secondary waste forms containing reductants will provide overestimated diffusivity values for 99Tc. Therefore, it is not appropriate to use Re as a surrogate 99Tc in future low temperature waste form studies. (3) Iodine diffusivity: ANSI/ANS 16.1, ASTM C1308, and EPA 1315 tests indicated that the three waste forms had leachability indices that were below the target LI > 11 for iodine. Therefore, it may be necessary to use a more effective sequestering material than silver zeolite used in two of the waste forms (Ceramicrete and DuraLith); (4) Sodium diffusivity: All the waste form specimens tested by the three leach methods (ANSI/ANS 16.1, ASTM C1308, and EPA 1315) exceeded the target LI value of 6; (5) All three leach methods (ANS 16.1, ASTM C1308 and EPA 1315) provided similar 99Tc diffusivity values for both short-time transient diffusivity effects as well as long-term ({approx}90 days) steady diffusivity from each of the three tested waste forms (Cast Stone 2M, Ceramicrete and DuraLith). Therefore, any one of the three methods can be used to determine the contaminant diffusivities from a selected waste form.
The Nevada National Security Site (NNSS) is located approximately 105 km (65 mi) northwest of Las Vegas, Nevada. The U.S. Department of Energy National Nuclear Security Administration Nevada Site Office (NNSA/NSO) is the federal lands management authority for the NNSS and National Security Technologies, LLC (NSTec) is the Management and Operations contractor. Access on and off the NNSS is tightly controlled, restricted, and guarded on a 24-hour basis. The NNSS is posted with signs along its entire perimeter. NSTec is the operator of all solid waste disposal sites on the NNSS. The Area 5 Radioactive Waste Management Site (RWMS) is the location of the permitted facility for the Solid Waste Disposal Site (SWDS). The Area 5 RWMS is located near the eastern edge of the NNSS (Figure 1), approximately 26 km (16 mi) north of Mercury, Nevada. The Area 5 RWMS is used for the disposal of low-level waste (LLW) and mixed low-level waste. Many areas surrounding the RWMS have been used in conducting nuclear tests. The site will be used for the disposal of regulated Asbestiform Low-Level Waste (ALLW), small quantities of low-level radioactive hydrocarbon-burdened (LLHB) media and debris, LLW, LLW that contains Polychlorinated Biphenyl (PCB) Bulk Product Waste greater than 50 ppm that leaches at a rate of less than 10 micrograms of PCB per liter of water, and small quantities of LLHB demolition and construction waste (hereafter called permissible waste). Waste containing free liquids, or waste that is regulated as hazardous waste under the Resource Conservation and Recovery Act (RCRA) or state-of-generation hazardous waste regulations, will not be accepted for disposal at the site. Waste regulated under the Toxic Substances Control Act (TSCA) that will be accepted at the disposal site is regulated asbestos-containing materials (RACM) and PCB Bulk Product Waste greater than 50 ppm that leaches at a rate of less than 10 micrograms of PCB per liter of water. The term asbestiform is used throughout this document to describe RACM. The disposal site will be used as a depository of permissible waste generated both on site and off site. All generators designated by NNSA/NSO will be eligible to dispose regulated ALLW at the Asbestiform Low-Level Waste Disposal Site in accordance with the DOE/NV-325, Nevada National Security Site Waste Acceptance Criteria (NNSSWAC, current revision). Approval will be given by NNSA/NSO to generators that have successfully demonstrated through process knowledge (PK) and/or sampling and analysis that the waste is low-level, contains asbestiform material, or contains PCB Bulk Product Waste greater than 50 ppm that leaches at a rate of less than 10 micrograms of PCB per liter of water, or small quantities of LLHB demolition and construction waste and does not contain prohibited waste materials. Each waste stream will be approved through the Radioactive Waste Acceptance Program (RWAP), which ensures that the waste meets acceptance requirements outlined in the NNSSWAC.
Producing a valuable chemical product through diversion of wet wastes can simultaneously resolve the problems associated with increasing wastes and greenhouse gas emissions from conventional chemical production processes. In this work, we investigated the life-cycle greenhouse gas emissions, water, and fossil-fuel consumption for waste-derived polylactic acids (PLA) from three different waste feedstocks, namely wastewater sludge, food waste, and swine manure, using the Greenhouse Gases, Regulated Emissions, and Energy Use in Technologies (GREET) model. The decarbonization potential of replacing fossil-based resins with the waste-derived polymer was also investigated. The results show that swine manure-to-PLA pathway was the least carbon intensive (—1.4 kgCO 2 e/kg) among the three waste-to-PLA pathways on a cradle-to-grave basis, followed by the food waste case (—1.3 kgCO 2 e/kg) and then by the wastewater sludge case (0.6 kgCO 2 e/kg). In the baseline scenario, all three waste-to-PLA pathways were less carbon intensive than both fossil-based PET and HDPE on a cradle-to-grave basis: 66% (vs. PET) and 56% (vs. HDPE), 171 and 192%, 181 and 205% reduction in GHG emissions for wastewater sludge-, food waste-, and swine manure-to-PLA pathway, respectively. For all sensitivity cases investigated, the food waste- and swine manure-to-PLA pathways were significantly less carbon intensive than their fossil-counterparts. In terms of the annual decarbonization potential of replacing fossil-based PET or HDPE, the wastewater sludge- and food waste-pathway showed higher mitigation potential than the swine manure-pathway: i) 18–28 kilotons CO 2 e-reduction per year for wastewater sludge pathway; ii) 23–26 kTCO 2 e-reduction/yr for food waste pathway; and iii) about 5 kTCO 2 e-reduction/yr for swine manure pathway depending on the type of conventional resin replaced. However, given the abundant availability of the swine manure feedstocks across the United States, the decarbonization potential of swine manure-based pathway can also increase as the plant capacity or the number of plants grow.
In this study, glass ceramics were explored as an alternative waste form for glass, the current baseline, to be used for immobilizing alkaline/alkaline earth + lanthanide (CS+LN) or CS+LN+transition metal (TM) fission-product waste streams generated by a uranium extraction (UREX+) aqueous separations type process. Results from past work on a glass waste form for the combined CS+LN waste streams showed that as waste loading increased, large fractions of crystalline phases precipitated upon slow cooling. The crystalline phases had no noticeable impact on the waste form performance by the 7-day product consistency test (PCT). These results point towards the development of a glass ceramic waste form for treating CS+LN or CS+LN+TM combined waste streams. Three main benefits for exploring glass ceramics are: • Glass ceramics offer increased solubility of troublesome components in crystalline phases as compared to glass, leading to increased waste loading; • The crystalline network formed in the glass ceramic results in higher heat tolerance than glass; and • These glass ceramics are designed to be processed by the same melter technology as the current baseline glass waste form. It will only require adding controlled canister cooling for crystallization into a glass ceramic waste form. Highly annealed waste form (essentially crack free) with up to 50X lower surface area than a typical High-Level Waste (HLW) glass canister. Lower surface area translates directly into increased durability. This was the first full year of exploring glass ceramics for the Option 1 and 2 combined waste stream options. This work has shown that dramatic increases in waste loading are achievable by designing a glass ceramic waste form as an alternative to glass. Table S1 shows the upper limits for heat, waste loading (based on solubility), and the decay time needed before treatment can occur for glass and glass ceramic waste forms. The improvements are significant for both combined waste stream options in terms of waste loading and/or decay time required before treatment. For Option 1, glass ceramics show an increase in waste loading of 15 mass % and reduction in decay time of 24 years. Decay times of ≈50 years or longer are close to the expected age of the fuel that will be reprocessed when the modified open or closed fuel cycle is expected to be put into action. Option 2 shows a 2x to 2.5x increase in waste loading with decay times of only 45 years. Note that for Option 2 glass, the required decay time before treatment is only 35 years because of the waste loading limits related to the solubility of MoO 3 in glass. If glass was evaluated for similar waste loadings as those achieved in Option 2 glass ceramics, the decay time would be significantly longer than 45 years. These glass ceramics are not optimized, but already they show the potential to dramatically reduce the amount of waste generated while still utilizing the proven processing technology used for glass production.
The Hanford Tank Waste Treatment and Immobilization Plant (WTP) is being constructed to treat the 56 million gallons of radioactive waste stored in 177 underground tanks at the Hanford Site. The WTP includes a pretreatment facility to separate the wastes into high-level waste (HLW) and low-activity waste (LAW) fractions for vitrification and disposal. The LAW will be converted to glass for final disposal at the Integrated Disposal Facility (IDF). Cast Stone – a cementitious waste form, has been selected for solidification of this secondary waste stream after treatment in the ETF. The secondary-waste Cast Stone waste form must be acceptable for disposal in the IDF. This secondary waste Cast Stone waste form qualification testing plan outlines the testing of the waste form and immobilization process to demonstrate that the Cast Stone waste form can comply with the disposal requirements. Specifications for the secondary-waste Cast Stone waste form have not been established. For this testing plan, Cast Stone specifications are derived from specifications for the immobilized LAW glass in the WTP contract, the waste acceptance criteria for the IDF, and the waste acceptance criteria in the IDF Permit issued by the State of Washington. This testing plan outlines the testing needed to demonstrate that the waste form can comply with these waste form specifications and acceptance criteria. The testing program must also demonstrate that the immobilization process can be controlled to consistently provide an acceptable waste form product. This testing plan also outlines the testing needed to provide the technical basis for understanding the long-term performance of the waste form in the disposal environment. These waste form performance data are needed to support performance assessment analyses of the long-term environmental impact of the secondary-waste Cast Stone waste form in the IDF
The Hanford Site Effluent Treatment Facility (ETF) currently treats aqueous waste streams generated during site cleanup activities. When the Hanford Tank Waste Treatment and Immobilization Plant (WTP) begins operations, including Direct Feed Low Activity Waste (DFLAW) vitrification, a liquid secondary waste (LSW) stream from the WTP will need to be treated. The volume of effluent for treatment at the ETF will increase significantly. The powdered salt waste form produced by the ETF will be replaced by a stabilized solidified waste form for disposal in Hanford’s Integrated Disposal Facility (IDF). Washington River Protection Solutions is implementing a Secondary Liquid Waste Immobilization Technology Development Plan to address the technology needs for a waste form and solidification process to treat the increased volume of waste planned for disposal at the IDF. Waste form testing to support this plan is composed of work in the near term to provide data as input to a performance assessment (PA) for Hanford’s IDF. In 2015, three Hanford Liquid Secondary Waste simulants were developed based on existing and projected waste streams. Using these waste simulants, fourteen mixes of Hanford Liquid Secondary Waste were prepared and tested varying the waste simulant, the water-to-dry materials ratio, and the dry materials blend composition.1 In FY16, testing was performed using a simulant of the EMF process condensate blended with the caustic scrubber—from the Low Activity Waste (LAW) melter—, processed through the ETF. The initial EMF-16 simulant will be based on modeling efforts performed to determine the mass balance of the ETF for the DFLAW.2 The compressive strength of all of the mixes exceeded the target of 3.4 MPa (500 psi) to meet the requirements identified as potential IDF Waste Acceptance Criteria in Table 1 of the Secondary Liquid Waste Immobilization Technology Development Plan.3 The hydraulic properties of the waste forms tested (hydraulic conductivity and water characteristic curves) were comparable to the properties measured on the Savannah River Site (SRS) Saltstone waste form. Future testing should include efforts to first; 1) determine the rate and amount of ammonia released during each unit operation of the treatment process to determine if additional ammonia management is required, then; 2) reduce the ammonia content of the ETF concentrated brine prior to solidification, making the waste more amenable to grouting, or 3) manage the release of ammonia during production and ongoing release during storage of the waste form, or 4) develop a lower pH process/waste form thereby precluding ammonia release.
Thermal ignition of radioactive waste within a 55-gallon drum was simulated by using a pressure-dependent waste decomposition model (Hobbs et al. in Process Saf Environ Prot https://doi.org/10.1016/j.psep.2022.09.047, 2022) calibrated with data from full-scale drum experiments (Parker et al. in The thermolytic response of a surrogate RNS waste mixture at the drum scale. Los Alamos National Laboratory Report LA-UR-16-21760, 2016) and validated with experiments from multiple laboratories (Hobbs et al. in Thermal analysis of aged nitric acid-soaked kitty litter in TRU waste drums-23370.WM2023 Conference, Phoenix, AZ, 2023). The acceleration of nitric acid chemistry reacting with an organic cat litter leading to thermal ignition was likely triggered by a restricted vent in the drum. Here, we address whether the form of the rate equation in (Hobbs et al. in Process Saf Environ Prot https://doi.org/10.1016/j.psep.2022.09.047, 2022) is sufficient to extrapolate thermal ignition within aged drums of similar content that have been stored in Texas for over nine years by investigating four different reaction rate forms for waste decomposition. A critical reaction rate reduction analysis is performed on each of these models to determine if delayed thermal runaway within vented aged waste is possible after nine years. We found that a pressure-dependent first-order rate expression not only predicted the accidental ignition of the waste drum, but the form also matches multiple experiments from different laboratories. Even though the waste composition decreases over time, the model predicts that acceleration leading to thermal runaway is possible if the waste is confined, even after 9 years. In conclusion, waste containing oxidizers such as nitric acid should not be mixed with organic adsorbents, especially if the waste is confined.
The U.S. Department of Energy's Office of River Protection (ORP) is responsible for the retrieval, treatment, immobilization, and disposal of Hanford's tank waste. Currently there are approximately 56 million gallons of highly radioactive mixed wastes awaiting treatment. A key aspect of the River Protection Project (RPP) cleanup mission is to construct and operate the Waste Treatment and Immobilization Plant (WTP). The WTP will separate the tank waste into high-level and low-activity waste (LAW) fractions, both of which will subsequently be vitrified. The projected throughput capacity of the WTP LAW Vitrification Facility is insufficient to complete the RPP mission in the time frame required by the Hanford Federal Facility Agreement and Consent Order, also known as the Tri-Party Agreement (TPA), i.e. December 31, 2047. Therefore, Supplemental Treatment is required both to meet the TPA treatment requirements as well as to more cost effectively complete the tank waste treatment mission. The Supplemental Treatment chosen will immobilize that portion of the retrieved LAW that is not sent to the WTP's LAW Vitrification facility into a solidified waste form. The solidified waste will then be disposed on the Hanford site in the Integrated Disposal Facility (IDF). In addition, the WTP LAW vitrification facility off-gas condensate known as WTP Secondary Waste (WTP-SW) will be generated and enriched in volatile components such as Cs-137, I-129, Tc-99, Cl, F, and SO4 that volatilize at the vitrification temperature of 1150 C in the absence of a continuous cold cap. The current waste disposal path for the WTP-SW is to recycle it to the supplemental LAW treatment to avoid a large steady state accumulation in the pretreatment-vitrification loop. Fluidized Bed Steam Reforming (FBSR) offers a moderate temperature (700-750 C) continuous method by which LAW and/or WTP-SW wastes can be processed irrespective of whether they contain organics, nitrates, sulfates/sulfides, chlorides, fluorides, volatile radionuclides or other aqueous components. The FBSR technology can process these wastes into a crystalline ceramic (mineral) waste form. The mineral waste form that is produced by co-processing waste with kaolin clay in an FBSR process has been shown to be as durable as LAW glass. Monolithing of the granular FBSR product is being investigated to prevent dispersion during transport or burial/storage but is not necessary for performance. A Benchscale Steam Reformer (BSR) was designed and constructed at the Savannah River National Laboratory (SRNL) to treat actual radioactive wastes to confirm the findings of the non-radioactive FBSR pilot scale tests and to qualify the waste form for applications at Hanford. Radioactive testing commenced in 2010 with a demonstration of Hanford's WTP-SW where Savannah River Site (SRS) High Level Waste (HLW) secondary waste from the Defense Waste Processing Facility (DWPF) was shimmed with a mixture of I-125/129 and Tc-99 to chemically resemble WTP-SW. Ninety six grams of radioactive product were made for testing. The second campaign commenced using SRS LAW chemically trimmed to look like Hanford's LAW. Six hundred grams of radioactive product were made for extensive testing and comparison to the non-radioactive pilot scale tests. The same mineral phases were found in the radioactive and non-radioactive testing.
In times of continuing fiscal constraints, a management and operation tool that is straightforward to implement, works as advertised, and virtually ensures compliant waste packaging should be carefully considered and employed wherever practicable. In the near future, the Department of Energy (DOE) will issue the first major update to DOE Order 435.1, Radioactive Waste Management. This update will contain a requirement for sites that do not have a Waste Isolation Pilot Plant (WIPP) waste certification program to use two newly developed technical standards: Contact-Handled Defense Transuranic Waste Packaging Instructions and Remote-Handled Defense Transuranic Waste Packaging Instructions. The technical standards are being developed from the DOE O 435.1 Notice, Contact-Handled and Remote-Handled Transuranic Waste Packaging, approved August 2011. The packaging instructions will provide detailed information and instruction for packaging almost every conceivable type of transuranic (TRU) waste for disposal at WIPP. While providing specificity, the packaging instructions leave to each site's own discretion the actual mechanics of how those Instructions will be functionally implemented at the floor level. While the Technical Standards are designed to provide precise information for compliant packaging, the density of the information in the packaging instructions necessitates a type of Rosetta Stone that translates the requirements into concise, clear, easy to use and operationally practical recipes that are waste stream and facility specific for use by both first line management and hands-on operations personnel. The Waste Generator Instructions provide the operator with step-by-step instructions that will integrate the sites' various operational requirements (e.g., health and safety limits, radiological limits or dose limits) and result in a WIPP certifiable waste and package that can be transported to and emplaced at WIPP. These little known but widely productive Waste Generator Instructions (WGIs) have been used occasionally in the past at large sites for treatment and packaging of TRU waste. The WGIs have resulted in highly efficient waste treatment, packaging and certification for disposal of TRU waste at WIPP. For example, a single WGI at LANL, combined with an increase in gram loading, resulted in a mind boggling 6,400% increase in waste loading for {sup 238}Pu heat source waste. In fact, the WGI combined with a new Contact Handled (CH) TRU Waste Content (TRUCON) Code provided a massive increase in shippable wattage per Transuranic Package Transporter-II (TRUPACT-II) over the previously used and more restrictive TRUCON Code that have been used previously for the heat source waste. In fact, the use of the WGI process at LANL's TA-55 facility reduced non-compliant drums for WIPP certification and disposal from a 13% failure rate down to a 0.5% failure rate and is expected to further reduce the failure rate to zero drums per year. The inherent value of the WGI is that it can be implemented in a site's current procedure issuance process and it provides documented proof of what actions were taken for each waste stream packaged. The WGI protocol provides a key floor-level operational component to achieve goal alignment between actual site operations, the WIPP TRU waste packaging instructions, and DOE O 435.1. (authors)
The Hanford Site in southeast Washington State has 56 million gallons of radioactive and chemically hazardous wastes stored in 177 underground tanks (ORP 2010). The U.S. Department of Energy (DOE), Office of River Protection (ORP), through its contractors, is constructing the Hanford Tank Waste Treatment and Immobilization Plant (WTP) to convert the radioactive and hazardous wastes into stable glass waste forms for disposal. Within the WTP, the pretreatment facility will receive the retrieved waste from the tank farms and separate it into two treated process streams. These waste streams will be vitrified, and the resulting waste canisters will be sent to offsite (high-level waste [HLW]) and onsite (immobilized low-activity waste [ILAW]) repositories. As part of the pretreatment and ILAW processing, liquid secondary wastes will be generated that will be transferred to the Effluent Treatment Facility (ETF) on the Hanford Site for further treatment. These liquid secondary wastes will be converted to stable solid waste forms that will be disposed of in the Integrated Disposal Facility (IDF). To support the selection of a waste form for the liquid secondary wastes from WTP, Washington River Protection Solutions (WRPS) has initiated secondary waste form testing work at Pacific Northwest National Laboratory (PNNL). In anticipation of a down-selection process for a waste form for the Solidification Treatment Unit to be added to the ETF, PNNL is developing data packages to support that down-selection. The objective of the data packages is to identify, evaluate, and summarize the existing information on the four waste forms being considered for stabilizing and solidifying the liquid secondary wastes. At the Hanford Site, the FBSR process is being evaluated as a supplemental technology for treating and immobilizing Hanford LAW radioactive tank waste and for treating secondary wastes from the WTP pretreatment and LAW vitrification processes.
This report describes the scientific basis underlying the approach being followed to design and develop “advanced” glass-bonded sodalite ceramic waste form (ACWF) materials that can (1) accommodate higher salt waste loadings than the waste form developed in the 1990s for EBR-II waste salt and (2) provide greater flexibility for immobilizing extreme waste salt compositions. This is accomplished by using a binder glass having a much higher Na 2 O content than glass compositions used previously to provide enough Na+ to react with all of the Cl– in the waste salt and generate the maximum amount of sodalite. The phase compositions and degradation behaviors of prototype ACWF products that were made using five new binder glass formulations and with 11-14 mass% representative LiCl/KCl-based salt waste were evaluated and compared with results of similar tests run with CWF products made using the original binder glass with 8 mass% of the same salt to demonstrate the approach and select a composition for further studies. About twice the amount of sodalite was generated in all ACWF materials and the microstructures and degradation behaviors confirmed our understanding of the reactions occurring during waste form production and the efficacy of the approach. However, the porosities of the resulting ACWF materials were higher than is desired. These results indicate the capacity of these ACWF waste forms to accommodate LiCl/KCl-based salt wastes becomes limited by porosity due to the low glass-to-sodalite volume ratio. Three of the new binder glass compositions were acceptable and there is no benefit to further increasing the Na content as initially planned. Instead, further studies are needed to develop and evaluate alternative production methods to decrease the porosity, such as by increasing the amount of binder glass in the formulation or by processing waste forms in a hot isostatic press. Increasing the amount of binder glass to eliminate porosity will decrease the waste loading from about 12% to 10% on a mass basis, but this will not significantly impact the waste loading on a volume basis. It is likely that heat output will limit the amount of waste salt that can be accommodated in a waste canister rather than the salt loading in an ACWF, and that the increase from 8 mass% to about 10 mass% salt loadings in ACWF materials will be sufficient to optimize these waste forms. Although the waste salt composition used in this study contained a moderate amount of NaCl, the test results suggest waste salts with little or no NaCl can be accommodated in ACWF materials by using the new binder glass, albeit at waste loadings lower than 8 mass%. The higher glass contents that will be required for ACWF materials made with salt wastes that do not contain NaCl are expected to result in much lower porosities in those waste forms.