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At least 1,117 records · Page 62
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

High Temperature Gas-cooled Reactor (HTGR) Graphite Pebble Fuel: Review of Technologies for Reprocessing

This report reviews literature on reprocessing high temperature gas-cooled reactor graphite fuel components. A basic review of the various fuel components used in the pebble bed type reactors is provided along with a survey of synthesis methods for the fabrication of the fuel components. Several disposal options are considered for the graphite pebble fuel elements including the storage of intact pebbles, volume reduction by separating the graphite from fuel kernels, and complete processing of the pebbles for waste storage. Existing methods for graphite removal are presented and generally consist of mechanical separation techniques such as crushing and grinding chemical techniques through the use of acid digestion and oxidation. Potential methods for reprocessing the graphite pebbles include improvements to existing methods and novel technologies that have not previously been investigated for nuclear graphite waste applications. The best overall method will be dependent on the desired final waste form and needs to factor in the technical efficiency, political concerns, cost, and implementation.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2015

High Temperature Gas-cooled Reactor (HTGR) Graphite Pebble Fuel: Review of Technologies for Reprocessing

This report reviews literature on reprocessing high temperature gas-cooled reactor graphite fuel components. A basic review of the various fuel components used in the pebble bed type reactors is provided along with a survey of synthesis methods for the fabrication of the fuel components. Several disposal options are considered for the graphite pebble fuel elements including the storage of intact pebbles, volume reduction by separating the graphite from fuel kernels, and complete processing of the pebbles for waste storage. Existing methods for graphite removal are presented and generally consist of mechanical separation techniques such as crushing and grinding and chemical techniques through the use of acid digestion and oxidation. Potential methods for reprocessing the graphite pebbles include improvements to existing methods and novel technologies that have not previously been investigated for nuclear graphite waste applications. The best overall method will be dependent on the desired final waste form and needs to factor in the technical efficiency, political concerns, cost, and implementation.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2015

Office of River Protection Advanced Low-Activity Waste Glass Research and Development Plan

The U.S. Department of Energy Office of River Protection (ORP) has initiated and leads an integrated Advanced Waste Glass (AWG) program to increase the loading of Hanford tank wastes in glass while meeting melter lifetime expectancies and process, regulatory, and product performance requirements. The integrated ORP program is focused on providing a technical, science-based foundation for making key decisions regarding the successful operation of the Hanford Tank Waste Treatment and Immobilization Plant (WTP) facilities in the context of an optimized River Protection Project (RPP) flowsheet. The fundamental data stemming from this program will support development of advanced glass formulations, key product performance and process control models, and tactical processing strategies to ensure safe and successful operations for both the low-activity waste (LAW) and high-level waste vitrification facilities. These activities will be conducted with the objective of improving the overall RPP mission by enhancing flexibility and reducing cost and schedule.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Summary of ALSEP Test Loop Solvent Irradiation Testing

Separating the minor actinide elements (americium and curium) from the fission product lanthanides is an important step in closing the nuclear fuel cycle. Isolating the minor actinides will allow transmuting them to short lived or stable isotopes in fast reactors, thereby reducing the long-term hazard associated with these elements. The Actinide Lanthanide Separation Process (ALSEP) is being developed by the DOE-NE Material Recovery and Waste Form Development Campaign to accomplish this separation with a single process. To develop a fundamental understanding of the solvent degradation mechanisms for the ALSEP Process, testing was performed in the INL Radiolysis/Hydrolysis Test Loop for the extraction section of the ALSEP flowsheet. This work culminated in the completion of the level two milestone (M2FT-16IN030102021) "Complete ALSEP test loop solvent irradiation test.” This report summarizes the testing performed and the impact of radiation on the ALSEP Process performance as a function of dose.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2017

Evaluation of ALSEPO

The level three milestone (M3FT-17IN030102013) "Evaluation of ALSEPO” has been completed. Researchers at INL are studying the impacts of gamma radiolysis on the Actinide Lanthanide Separation Process (ALSEP) flowsheet. The ALSEP process is being developed by the DOE-NE Material Recovery and Waste Form Development Campaign. The process solvent used a combination of the solvating extractant N,N,N’,N’-tetra(2-ethylhexyl)diglycolamide and the cation exchanging extractant 2-ethylhexylphosphonic acid mono-2-ethylehxyl ester dissolved in an aliphatic diluent. The actinides and lanthanides are co-extracted from nitric acid solution and the actinides are selectively stripped using a carboxylic acid buffered aminopolycarboxylic acid solution. The results irradiation studies previously performed at the INL on another diglycolamide-based solvent extraction system containing 1-octanol as a phase modifier suggested that the octanol may be serving to inhibit the radiolytic degradation of the ALSEP extractants. Although the mechanism of this radioprotection was not determined, the addition of octanol to the ALSEP solvent was proposed. The goal of this research program was to establish the mechanism responsible for the observed increase in the radiation hardiness of the ALSEP solvent upon the addition of 1-octanol. In addition, other possible enhancements of solvent behavior such as possible increased resistance to third phase formation and enhanced extraction/stripping kinetics were examined. The addition of 1-octanol to the ALSEP formulation at either 1 % or 5 % (v/v) does reduce the rate of degradation of the solvent when exposed to gamma radiation. Unfortunately, the addition of the polar phase modifier essentially destroyed the An/Ln separation usually achievable with ALSEP chemistry. This loss of An/Ln separation ability is presumably do to the disruption of HEH[EHP] dimer formation due to the addition of the polar alcohol. The addition of octanol does not appear to have any significant impact upon the rate of removal of either americium or europium radiotracer from the loaded organic solvents. Based upon the distribution ratio data obtained for the 1% octanol and 5 % octanol ALSEPO solvent systems and the lack of any enhancement in the rate of stripping of the actinides and lanthanides from the loaded solvent, further efforts to reformulate the ALSEPO solvent were abandoned.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2015

Milestone report - M4FT-15OR03120210 - Multi-lab Analytical Plan for Analysis of Legacy 85 Kr Samples

Legacy samples composed of 85 Kr encapsulated in solid zeolite 5A material and five small metal tubes containing a mixture of the zeolite combined with a glass matrix resulting from hot isostatic pressing have been preserved. The samples were a result of krypton R&D encapsulation efforts in the late 1970s performed at the Idaho Chemical Processing Plant. These samples were shipped to Oak Ridge National Laboratory (ORNL) in mid-FY 2014. Upon receipt the outer shipping package was opened and the inner package removed and placed in a radiation hood. The individual capsules were double bagged as they were removed from the inner shipping pig and placed into individual glass sample bottles for further analysis. The five capsules were then x-ray imaged. Capsules 1 and 4 appear to contain an amorphous mass within the capsules. Capsule 2 clearly shows the saw marks on the capsule and a quantity of loose pellet or bead-like material remaining in the capsule. Capsule 3 shows similar bead-like material within the intact capsule. Capsule 5 was previously opened. The end of this capsule appears to have been cut off and there are additional saw marks on the side of the capsule. X-ray tomography allowed the capsules to be viewed along the three axes. Of most interest was determining whether there was any residual material in the closed end of Capsule 5. The images confirmed the presence of residual material within this capsule. The material appears to be compacted but still retains some of the bead-like morphology. A conference call was held on February 19, 2015, with participation from ORNL, Idaho National Laboratory, Sandia National Laboratories, and Pacific Northwest National Laboratory Sigma Team members. The nondestructive analysis (NDA) results were discussed, and a proposed path forward was formulated to advance this effort toward the original goals of understanding the effects of extended storage on the waste form and package. Based on the initial NDA and the fact that there are at least two breached samples it was proposed that exploratory tests be conducted with the breached specimens before opening the three intact capsules. Portions of these would be analyzed to determine the fraction of krypton/xenon remaining in the matrix and the amount of rubidium remaining in the matrix. The inner surface of the breached capsules would be examined for corrosion.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

NTRD Technical Monthly October FY18

Topics covered in this Nuclear Technology and Research Development (NTRD) monthly update include: Advanced Fuels Campaign, Material Recovery and Waste Forms Development, MPACT Campaign, Fuel Cycle Options Campaign, Joint Fuel Cycle Study Activities, and AFCI-HQ Program Support.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2017

Preliminary Desorption studies for HZ-PAN and AgZ-PAN

Adsorption of Kr and Xe on HZ-PAN and AgZ-PAN has been the studied extensively. Prior research focused on sorbent capacity and breakthrough of Kr and Xe, with desorption cycles completed in order to close material balances and prepare sorbents for further adsorption testing. This series of tests was designed to determine preliminary information about desorption to guide further research to optimize desorption cycles for each sorbent. A series of desorption tests were run using thermal and pressure swing operations. For AgZ-PAN, these tests indicated that both heat and carrier gas are likely necessary to removed adsorbed gases. However, vacuum pressure and heat may be sufficient to desorb gases from HZ-PAN, which should result in a cleaner Kr stream during desorption. Desorption optimization for both sorbents merits further study in order to make final waste form volume as small as possible.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2015

Final Technical Report on Fluoride Salt Study

This report fulfills the Level 3 Milestone No. M3FT-15IN0311022 titled, “Uranium Electrorefining Using Fluoride Salt” within the Department of Energy (DOE) Work Package No. FT-15IN031102 titled, “U/TRU Codeposition and Fluoride Salt Studies – INL”. This work package falls under the Fuel Cycle Research and Development (FCR&D) Materials Recovery and Waste Form Development (MRWFD) Program 1.02.03.11 titled “Domestic Echem”. The electrorefining of uranium in a LiF-NaF-KF, or FLiNaK, salt containing UF 3 has been performed. Several gram-scale electrodeposits of uranium were collected exhibiting a dendritic morphology similar to uranium electrorefining in chloride salts. Additionally, cyclic voltammetry experiments have been performed at 773 K in FLiNaK-UF 4 , FLiNaK-UF 3 , and FLiNaK-UF 3 -LaF 3 salt mixtures to analyze the feasibility of electrorefining uranium in the FLiNaK salt containing lanthanides. Results are promising, showing a 0.48 V potential window between uranium and lanthanum depositions.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2018

Nuclear Technology Research and Development (NTRD) Technical Monthly June FY18

The Nuclear Technology Research and Development (NTRD) Technical Monthly Report for June FY18 covers the following areas: Advanced Fuels Campaign, Material Recovery and Waste Forms Development, MPACT Campaign, Fuel Cycle Options Campaign, Joint Fuel Cycle Study Activities, and, AFCI-HQ Program Support.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Nuclear Fuel Cycle and Supply Chain (NFCSC) Technical Monthly June FY-19

The monthly technical report for the Nuclear Fuel Cycle and Supply Chain (NFCSC) for June FY19 is provided. Major sections include: Advanced fuels campaign; Material recovery and waste forms development; MPACT campaign; Systems analysis and integration campaign; Joint fuel cycle study activities; and, AFCI-HQ program support.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Nuclear Fuel Cycle and Supply Chain (NFCSC) Technical Monthly October FY-20

The October FY20 Nuclear Fuel Cycle and Supply Chain (NFCSC) technical monthly report is provided. The usual topics are included: Advanced Fuels Campaign, Material Recovery and Waste Forms Development, MPACT Campaign, Systems Analysis and Integration Campaign, Joint Fuel Cycle Study Activities, and AFCI-HQ program Support.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Non-Destructive Imaging of a Liquid Moving Through Porous Media Using a Computer Tomography Scanner

The most common approach used by modelers to describe movement of liquids through a porous solid, such as cement, sediment, or glass, is to assume a uniform flow rate, such as a Darcy Flux or a diffusion constant. However, this convenient simplification is problematic because in many cases it ignors the presence of fractures and macropores, which commonly dominate water flow and contaminant transport. For this reason, it is common that such modeling results do not reflect the multi-modal flow detected in laboratory and field studies. The objective of this seedling study was to develop a new capability for SRNL to track liquid moving through micro- (matrix-) and macro-flow using an X-ray Computed Topography (CT) Scanner. 4-dimensional anamated renditions were created that permited quantifying traditional matrix flow and macropore flow. These animations were modelled using a public domain software, HYDRUS 1-D, describing one dimension, dual-porosity and dual-permeability processes. This new capability provides a proof of concept for reducing model uncertainty applicable to waste disposal risk calculations, environmental remediation, and waste form development when describing the movement of liquids as they pass through glass, cement, fractured rock, or soil.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

Agricultural Impacts on Nitrogen Cycling: Climate and Air Pollution (Final Technical Report)

We have successfully added a parameterization of ammonia emissions from synthetic fertilizer and manure from agriculture to Earth System Models. We have evaluated how emissions change in the future and the processes driving these changes. We have examined the impact of agricultural ammonia emissions on present-day air quality and have evaluated the impact of resolving the emissions with high temporal resolution. We have also examined the impact of how Earth System Models treat the cycling of emissions in soils. Our code, the Flows of Agricultural Nitrogen – version 2 – model (FANv2) has been run in both the CLM framework and the ELM framework. To my knowledge the code has not yet been fully implemented into ELM. Volatilization of ammonia (NH3) from fertilizers and livestock wastes forms a significant pathway of nitrogen losses in agricultural ecosystems and constitutes the largest source of atmospheric emissions of NH3. We have provided a major update to the process model FAN (Flow of Agricultural Nitrogen), which evaluates NH3 emissions interactively within an Earth system model; in this work, the Community Earth System Model (CESM) is used. The updated version (FANv2) includes a more detailed treatment of both physical and agricultural processes, which allows the model to differentiate between the volatilization losses from animal housings, manure storage, grazed pastures, and the application of manure and different types of mineral fertilizers. The modeled ammonia emissions are first evaluated at a local scale against experimental data for various types of fertilizers and manure, and they are subsequently run globally to evaluate NH3 emissions for 2010–2015 based on gridded datasets of fertilizer use and livestock populations. Comparison of regional emissions shows that FANv2 agrees with previous inventories for North America and Europe and is within the range of previous inventories for China. However, due to higher NH3 emissions in Africa, India, and Latin America, the global emissions simulated by FANv2(48 Tg N) are 30 %–40 % higher than in the existing inventories.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Physical Sciences Vistas (Issue 3 2020)

In this issue, highlights of our outstanding R&D supporting the Laboratory’s nuclear security mission include the following. 1. The essential nuclear materials science contributions of MST’s Materials Properties Team to a range of Lab missions, operations, and initiatives. 2. Work in the Sigma Complex supporting NNSA’s Advanced Manufacturing Development milestones by members of Sigma Division and colleagues across the Laboratory and other NNSA sites. 3. Greg Dale’s role in the Lab’s molybdenum program and today as a technical lead on the Scorpius project. 4. Measurements that reveal the role thermal interfaces play in dynamic compression experiments. 5. The first-ever synthesis of an actinide framework, which offers opportunities for understanding these structures as potential radioactive waste forms and provides new models of actinide species transport in the environment. This issue also showcases, as part of our commitment to simultaneous excellence in mission operations and community relations, the successful high-hazard repair of the LANSCE accelerator, which resulted in a large team Laboratory Distinguished Performance Award, and a virtual Summer Physics Camp for Young Women that brought together participants from around the world, even as COVID kept them socially distant in their homes.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Review of Potential Wigner Effect Impacts on the Irradiated Graphite in Decommissioned Hanford Reactors

This review of is motivated by the need to consider future disposal of the nine surplus Hanford Site production reactors (B, C, D, DR, F, H, KE, KW, and N) that are decommissioned as part of the Hanford Site Composite Analysis. The B Reactor has been designated as a museum. The other eight reactors will be evaluated in a future performance assessment before a final disposal facility can be authorized to construction or to receive this waste form. After a performance assessment is available, then the Hanford Site Composite Analysis would be updated to account for this additional source term. Disposal is currently assumed to occur in calendar year 2070 by one-piece removal to a projected disposal facility in the 200 West Area of the Hanford Site Central Plateau. The N Reactor core may also be disposed analogously to the single-pass reactors. It will further assume that the B Reactor will remain a museum permanently. The U.S. Department of Energy studied at least five decommissioning alternatives for long-term, safe management of radionuclide-contaminated materials inside the eight single-pass reactors (DOE/EIS-0119-FEIS, Decommissioning of Eight Surplus Production Reactors at the Hanford Site, Richland, Washington).

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Addendum to Capability Needs for Irradiated and Radioactive Materials Research (Ad Hoc Committee Summary Report)

Nuclear materials and fuels studies are challenging research and engineering targets because of their inherent radioactivity as well as their heterogeneous microstructure. Advanced light sources have made significant underpinning scientific contributions to the understanding of structural and fuel cladding material microstructure and properties and the development of structure-property relationships. These facilities have the potential to help advance the Department of Energy (DOE) Office of Nuclear Energy (DOE-NE) mission priorities providing underpinning understanding of technically important challenges, including: irradiation induced embrittlement and swelling; stress corrosion cracking and corrosion in extreme environments; ageing of reactor pressure vessels steels; nuclear fuel characterization; and nuclear waste form optimization as well as playing a major role in the development of a materials performance matrix to aid in the design of new materials to meet the needs of advanced reactor concepts. However, the delivery of underpinning understanding is the mission of DOE Office of Science (DOE-SC). While filling such knowledge gaps is important, efforts in this direction should not be confused with the strategic technology focused mission goals of DOE-NE to enable the continued operation of existing U.S. nuclear reactors, to enable the deployment of advanced nuclear reactors, to develop advanced nuclear fuel cycles, and to maintain U.S. leadership in nuclear energy technology.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗