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At least 253 records · Page 14

Comparing Legacy Waste Management to Advanced Reactor Waste Management

The Nuclear Energy Agency (NEA) and Natural Resources Canada (NRCan) are organizing an international workshop on the implementation of radioactive waste management and decommissioning strategies in small modular reactors (SMRs) and advance reactor technologies. The event will take place in Ottawa, Canada on 7-10 November 2022. The workshop will convene participants from various fields of expertise in the areas of radioactive waste management, decommissioning, nuclear science and development, transportation, as well as young professionals, communication experts and researchers. The goal of the workshop is to devise a guideline document that will serve implementers in understanding key issues in decommissioning and waste management of new reactors from the design perspective, aiding in the licensing process and in future decommissioning and waste management activities. DOE has invested considerably in the innovation of advanced reactors. Interaction in this workshop allows INL and DOE to articulate the importance of looking at the back-end of the fuel cycle for advanced reactors. The back-end of the fuel cycle is important to the success of advanced reactors, and DOE may need to manage this material in the future after it is discharged from reactors. I have been asked to present at the track titled "Operational and Design Optimization Consideration Related to Decommissioning and Radioactive Waste Management for SMRs/Advanced Reactors".

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Formulation and preparation of Hanford Waste Treatment Plant direct feed low activity waste Effluent Management Facility core simulant

The Hanford Waste Treatment and Immobilization Plant (WTP) Low Activity Waste (LAW) vitrification facility will generate an aqueous condensate recycle stream (LAW Melter Off-Gas Condensate, LMOGC) from the off-gas system. The baseline plan for disposition of this stream during full WTP operations is to send it to the WTP Pretreatment Facility, where it will be blended with LAW, concentrated by evaporation and recycled to the LAW vitrification facility. However, during the Direct Feed LAW (DFLAW) scenario, planned disposition of this stream is to evaporate it in a new evaporator in the Effluent Management Facility (EMF) and then return it to the LAW melter. It is important to understand the composition of the effluents from the melter and new evaporator so that the disposition of these streams can be accurately planned and accommodated. Furthermore, alternate disposition of the LMOGC stream would eliminate recycling of problematic components, and would enable less integrated operation of the LAW melter and the Pretreatment Facilities. Alternate disposition would also eliminate this stream from recycling within WTP when it begins operations and would decrease the LAW vitrification mission duration and quantity of glass waste, amongst the other problems such a recycle stream present. This LAW Melter Off-Gas Condensate stream will contain components that are volatile at melter temperatures and are problematic for the glass waste form, such as halides and sulfate. Because this stream will recycle within WTP, these components accumulate in the Melter Condensate stream, exacerbating their impact on the number of LAW glass containers that must be produced. Diverting the stream reduces the halides and sulfate in the recycled Condensate and is a key outcome of this work. This overall program examines the potential treatment and immobilization of this stream to enable alternative disposal. The objective of this task was to formulate and prepare a simulant of the LAW Melter Off-gas Condensate expected during DFLAW operations. That simulant can be used in evaporator testing to predict the composition of the effluents from the Effluent Management Facility (EMF) evaporator to aid in planning for their disposition. This document describes the method used to formulate a simulant of this LAW Melter Off-Gas Condensate stream, which, after pH adjustment, is the feed to the evaporator in the EMF.

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3rd Quarter Transportation Report FY2017 Waste Shipments To and From the Nevada National Security Site (NNSS), Radioactive Waste Management Complex

This report satisfies the U.S. Department of Energy (DOE), National Nuclear Security Administration Nevada Field Office (NNSA/NFO) commitment to prepare a quarterly summary report of waste shipments to the Nevada National Security Site (NNSS) Radioactive Waste Management Complex (RWMC) at Area 5. This report summarizes the 3rd quarter of fiscal year (FY) 2017 low-level radioactive waste (LLW), mixed low-level radioactive waste (MLLW), which includes classified LLW and MLLW, classified non-radioactive (CNR) and classified non-radioactive hazardous (CNRH) shipments. There were no shipments sent for offsite treatment from a NNSS facility and returned to the NNSS this quarter of FY2017. Tabular summaries are provided, which include the following: Sources of and carriers for LLW, MLLW and CNR/CNRH shipments to and from the NNSS; Number and external volume of LLW, MLLW and CNR/CNRH shipments; Highway routes used by carriers; and Incident/accident data applicable to LLW, MLLW and CNR/CNRH shipments.

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Waste management strategies for military-generated waste in the United States

Sustainable and energy efficient municipal solid waste (MSW) management is vital for the health and performance of deployed soldiers, as they play an important role in the safety and dignity of a country. As the United States targets net-zero carbon-free emission goals, research and development are essential to surpassing current practices for management of MSW at military installations, both at home and abroad. To achieve this, it is important to act upon and implement the policies and instructions set by government agencies such as the Environmental Protection Agency (EPA), the Department of Energy (DOE), and the Department of Defense (DoD). Understanding the composition of waste and disposal methods that are in use at military installations is a crucial step to success. Here, the authors show this through analyzed data from trusted sources, such as government agencies, reports, magazines, journals, and other publications on MSW management techniques. By defining these challenges, possible solutions can be better understood for improved management of MSW at military installations in the United States. Finally, an integrated approach with deployable units capable of waste-to-energy technology using waste reduction, diversion, and recycling strategies shows to be an effective pathway for MSW conversion into energy and other useful products.

09 BIOMASS FUELS↗

1st Quarter Transportation Report FY2017: Waste Shipments To and From the Nevada National Security Site (NNSS), Radioactive Waste Management Complex

This report satisfies the U.S. Department of Energy (DOE), National Nuclear Security Administration Nevada Field Office (NNSA/NFO) commitment to prepare a quarterly summary report of waste shipments to the Nevada National Security Site (NNSS) Radioactive Waste Management Complex (RWMC) at Area 5. This report summarizes the 1st quarter of fiscal year (FY) 2017 low-level radioactive waste (LLW), mixed low-level radioactive waste (MLLW) and classified non-radioactive (CNR) shipments. There were no shipments sent for offsite treatment from a NNSS facility and returned to the NNSS this quarter of FY2017.

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Unreviewed Disposal Question Evaluation: Disposal of the Lawrence Livermore National Laboratory EnergyX Macroencapsulation 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 Lawrence Livermore National Laboratory (LLNL) EnergyX Macroencapsulation mixed low-level waste (MLLW) (BCLAMACRONCAP, Revision 2 [LLNL 2017]) 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 LLNL EnergyX Macroencapsulation MLLW meets all U.S. Department of Energy (DOE) Manual DOE M 435.1-1, Radioactive Waste Management Manual, Chapter IV, Section P performance objectives (DOE 1999). The LLNL EnergyX Macroencapsulation waste stream is recommended for acceptance without conditions.

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Mercury Speciation in Savannah River Site High-Level Waste: Determination and Implications for Waste Handling and Disposal - 16178

As part of a larger program to address mercury issues at the Savannah River Site, a number of samples from across the salt processing flowsheet have been collected and analyzed for several mercury species. The results indicate the presence of organomercury species, predominately methylmercury cation. This result was not expected, and it represents a significant paradigm shift in the understanding of mercury chemistry in high-level tank waste. Concentrations of total and soluble mercury have been measured as high as 0.5 g/L with methylmercury concentrations of at least fifty percent of that value. The distribution of mercury species being observed have ramifications to waste processing strategies. In particular, the mercury behavior across the cesium solvent extraction process has been examined. Leachates, from toxicity testing of the cementitious waste form used for decontaminated salt waste at Savannah River, have been tested and shows methylmercury as the dominant extractable species. (authors)

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Treatment of Uranium Catalyst Waste for High Volume Reduction of the Final Waste to be Disposed - 19023

A large volume of problematic radioactive waste of spent uranium catalyst, approximately 7,000 drums was generated by a chemical company in Korea. The spent uranium catalyst has since been stored onsite awaiting a management strategy that is to minimize the volume/cost requirements for final disposal of the uranium-bearing waste. This work developed for the first time a process to greatly reduce the waste volume to be disposed while the secondary wastes generated from the process being released to the environment are controlled to meet the discharge criteria in Korea. (authors)

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Mechanical Waste Gathering System (MWGS), Alternate Retrieval of Hanford Tank Waste - 19188

Hanford has 149 underground single shell tanks; of which several have known or suspected leak sites. Sluicing with large volumes of solution in compromised leaking tanks is not desirable due to the risk of environmental release. To address the complex retrieval of hardpan nuclear waste in Hanford's single shell tanks, a Mechanical Waste Gathering System is being developed and tested, which breaks up the waste and moves it to the surfaces without the introduction of liquid to the tank bottom. To improve the removal of hardpan tank waste, WRPS has leveraged industry knowledge and previous experience to identify a solution. This technology will provide another option for the technology toolbox at Hanford. (authors)

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Special Analysis for the Disposal of the Idaho National Laboratory Unirradiated Light Water Breeder Reactor Rods and Pellets Waste Stream at the Area 5 Radioactive Waste Management Site, Nevada National Security Site, Nye County, Nevada

The purpose of this special analysis (SA) is to determine if the Idaho National Laboratory (INL) Unirradiated Light Water Breeder Reactor (LWBR) Rods and Pellets waste stream (INEL103597TR2, Revision 2) is suitable for disposal by shallow land burial (SLB) at the Area 5 Radioactive Waste Management Site (RWMS). The INL Unirradiated LWBR Rods and Pellets waste stream consists of 24 containers with unirradiated fabricated rods and pellets composed of uranium oxide (UO2) and thorium oxide (ThO2) fuel in zirconium cladding. The INL Unirradiated LWBR Rods and Pellets waste stream requires an SA because the 229 Th, 230 Th, 232 U, 233 U, and 234 U activity concentrations exceed the Nevada National Security Site (NNSS) Waste Acceptance Criteria (WAC) Action Levels.

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Advanced Waste Form and Melter Development for Treatment of Troublesome High-level Wastes

A number of waste components in US defense high level radioactive wastes (HLW) have proven challenging for current Joule heated ceramic melter (JHCM) operations and have limited the ability to increase waste loadings beyond already realized levels. Many of these "troublesome" waste species cause crystallization in the glass melt that can negatively impact product quality or have a deleterious effect on melter processing. Recent efforts at US Department of Energy laboratories have focused on understanding crystallization behavior within HLW glass melts and investigating approached to mitigate the impacts of crystallization so that increases in waste loading can be realized. Advanced glass formulations have been developed to highlight the unique benefits of next-generation melter technologies such as the Cold Crucible Induction Melter (CCIM). Crystal-tolerant HLW glasses have been investigated to allow sparingly soluble components such as chromium to crystallize in the melter but pass out of the melter before accumulating.

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International Approaches for Nuclear Waste Disposal in Geological Formations: Geological Challenges in Radioactive Waste Isolation—Fifth Worldwide Review

The overall objective of the Fifth Worldwide Review (WWR-5) is to document the current state-of-the-art of major developments in a number of nations throughout the World pursuing geological disposal programs, and to summarize challenging problems and experience that have been obtained in siting, preparing and reviewing cases for the operational and long-term safety of proposed and operating nuclear waste repositories. The scope of the Review is to address current specific technical issues and challenges in safety case development along with the interplay of technical feasibility, siting, engineering design issues, and operational and post-closure safety. In particular, the chapters included in the report present the following types of information: the current status of the deep geological repository programs for high level nuclear waste and low- and intermediate level nuclear waste in each country, concepts of siting and radioactive waste and spent nuclear fuel management in different countries (with the emphasis of nuclear waste disposal under different climatic conditions and different geological formations), progress in repository site selection and site characterization, technology development, buffer/backfill materials studies and testing, support activities, programs, and projects, international cooperation, and future plans, as well as regulatory issues and transboundary problems.

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Solid-liquid Separation Testing for the Remediation of Hanford Waste Treatment Plant Low Activity Waste Melter Off-Gas Condensate

The Low Activity Waste (LAW) vitrification facility at the Hanford Waste Treatment and Immobilization Plant (WTP) will generate an aqueous condensate stream (LAW Off-Gas Condensate) from the off-gas system. The plan for disposition of this stream during Direct Feed LAW operations is to transfer it to the Effluent Management Facility (EMF), where it will be concentrated by evaporation and recycled to the LAW vitrification facility again. The primary reason to recycle this stream is so that the semi-volatile 99Tc isotope eventually becomes incorporated into the glass. However, this stream also contains non-radioactive salt components that are problematic in the melter, so diversion of this stream to another process would eliminate recycling of these salts and would enable simplified operation of the LAW melter and the Pretreatment Facilities. This diversion from recycling this stream within WTP would have the effect of decreasing the quantity of glass waste produced by allowing further increases in waste loading, resulting in a shortened LAW vitrification mission duration. The concept being tested here involves selectively removing the 99 Tc so that the decontaminated aqueous stream, with the problematic salts, can be disposed as a different waste form and avoid reprocessing through vitrification.

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Recommended Updates to Solubility Controls for Modeling Leaching of Technetium, Uranium, Neptunium, Plutonium, and Iodine from the Residual Waste Layer of Closed Savannah River Site High Level Waste Tanks

The objective of this report is to relate waste leaching experiments by the Savannah River National Laboratory (SRNL) to performance assessment modeling of release of several radionuclides from residual waste in closed high-level waste tanks. SRNL leached residual waste from Tanks 18F and 12H with solutions simulating the modeled evolution of pore fluids in residual waste layers of closed tanks through various stages of grout degradation. Tc-99, uranium isotopes, Np-237, plutonium isotopes, and I-129 were analyzed in the leachate multiple times over 90 days.

07 ISOTOPE AND RADIATION SOURCES↗

Radioactive Demonstration Of Mineralized Waste Forms Made From Hanford Low Activity Waste (Tank SX-105 And AN-103) By Fluidized Bed Steam Reformation

One of the immobilization technologies under consideration as a Supplemental Treatment for Hanford’s Low Activity Waste (LAW) is Fluidized Bed Steam Reforming (FBSR). The FBSR technology forms a mineral waste form at moderate processing temperatures thus retaining and atomically bonding the halides, sulfates, and technetium in the mineral phases (nepheline, sodalite, nosean, carnegieite). Additions of kaolin clay are used instead of glass formers and the minerals formed by the FBSR technology offers (1) atomic bonding of the radionuclides and constituents of concern (COC) comparable to glass, (2) short and long term durability comparable to glass, (3) disposal volumes comparable to glass, and (4) higher Na2O and SO{sub 4} waste loadings than glass. The higher FBSR Na{sub 2}O and SO{sub 4} waste loadings contribute to the low disposal volumes but also provide for more rapid processing of the LAW. Recent FBSR processing and testing of Hanford radioactive LAW (Tank SX-105 and AN-103) waste is reported and compared to previous radioactive and non-radioactive LAW processing and testing.

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The Use of Positrons to Survey Alteration Layers on Synthetic Nuclear Waste Glasses

In order to safeguard society and the environment, understanding radioactive waste glass alteration mechanisms in interactions with solutions and near-field materials, such as Fe, is essential to nuclear waste repository performance assessments. Alteration products are formed at the surface of glasses after reaction with solution. In this study, glass altered in the presence of Fe0 in aqueous solution formed two alteration layers: one embedded with Fe closer to the surface and one without Fe found deeper in the sample. Both layers were found to be thinner than the alteration layer found in glass altered in aqueous solution only. For the first time, Doppler Broadening Positron Annihilation Spectroscopy (DB-PAS) is used to non-destructively characterize the pore structures of glass altered in the presence of Fe0. Advantages and disadvantages of DB-PAS compared to other techniques used to analyze pore structures for altered glass samples are discussed. Ultimately, DB-PAS has shown to be an excellent choice for pore structure characterization for glasses with multiple alteration layers. Monte Carlo modeling predicted positron trajectories through the layers, and helped explain DB-PAS data, which showed that the deeper alteration layer without Fe had a similar composition and pore structure to layers on glass altered in water only.

Doppler Broadening Positron Annihilation Spectrosc↗

Host-guest prospects of neodymium and gadolinium ultraphosphate frameworks for nuclear waste storage: Multi-temperature topological analysis of nanoporous cages in RP{sub 5}O{sub 14}

Highlights: • The temperature-dependent cage topologies of RP{sub 5}O{sub 14} (R = Nd or Gd) were examined. • A topological analysis revealed similar cage structure for RP{sub 5}O{sub 14} (R = Nd or Gd). • One exception: the 8/4 cage topology of NdP{sub 5}O{sub 14} lacks structural cross-linking. • Volume (UO{sub 2} or PuO{sub 2}) ≫ 8/4 topology in RP{sub 5}O{sub 14} (R = Nd or Gd). • RP{sub 5}O{sub 14} (R = Nd or Gd) are good prospective host media for nuclear waste storage. - Abstract: Rare-earth ultraphosphate (RP{sub 5}O{sub 14}) framework materials are potential host media for nuclear waste storage, since cages within their nanoporous structures have volumes that match well those of prospective guests such as uranium or plutonium ions. Good volume matches of host cages and guest compounds are nonetheless not the only structural requirement for ensuring viable nuclear waste storage. Host structures also need to be stable enough to withstand the typical environmental conditions of long-term storage of spent nuclear fuel. To this end, the nanoporous cage topologies of neodymium and gadolinium ultraphosphate, NdP{sub 5}O{sub 14} and GdP{sub 5}O{sub 14}, are investigated as a function of temperature. Topological analysis shows that, while both compounds are essentially isostructural, thus displaying the same type of cage structures, the cage volumes of NdP{sub 5}O{sub 14} are significantly larger than those of GdP{sub 5}O{sub 14}, with one stark exception. This exception concerns the cage of NdP{sub 5}O{sub 14} whose 8/4 topology lacks structural cross-linking that would otherwise give it much more strength. This 'squashed' cage appears to owe its origins to the specific nature of crystallographic twinning in NdP{sub 5}O{sub 14}, which causes strain that needs alleviating; squashing the 8/4 cage in NdP{sub 5}O{sub 14} would be the most susceptible option towards this end, since its cage manifests the weakest structural construct. GdP{sub 5}O{sub 14} succumbs to a gradual contraction of its 8/4 cage only with increasing temperature above 300 K; this is well below its second-order monoclinic-to-orthorhombic phase transition at 420–430 K; which is 420 K for NdP{sub 5}O{sub 14}. Fortunately, the volumes of heavy metal ions that arise from spent nuclear fuels do not match the size requirements of cages with 8/4 topology in RP{sub 5}O{sub 14} hosts needed for encapsulation; otherwise, radiation leakage of such containment would present a risk. Both NdP{sub 5}O{sub 14} and GdP{sub 5}O{sub 14} would therefore seem to offer good prospects as host media for nuclear waste storage.

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